GREEN ROOF SYSTEMS: PLANT SELECTION, CARBON SEQUESTRATION, ENERGY CONSERVATION, AND STORMWATER RUNOFF

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 0180269
• Project Start Date: Nov 1, 2008
• Project End Date: Oct 31, 2013
• Program Code: [(N/A)]- (N/A)

Recipient Organization
MICHIGAN STATE UNIV
(N/A)
EAST LANSING,MI 48824

Performing Department
Horticulture

Non Technical Summary
As forests, agricultural fields, and suburban and urban lands are replaced with impervious surfaces due to development, the necessity to recover green space is becoming increasingly critical to maintain environmental quality. Vegetated or green roofs are one potential remedy for this problem. Establishing plant material on rooftops provide numerous ecological and economic benefits including stormwater management, energy conservation, mitigation of the urban heat island effect, increased longevity of roofing membranes, as well as providing a more aesthetically pleasing environment in which to work and live. The purpose of this project is to evaluate potential plant species and to determine their ability to sequester carbon, mitigate stormwater runoff, and influence energy conservation.

Animal Health Component

(N/A)

Research Effort Categories

Basic

(N/A)

Applied

(N/A)

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
203	2199	1060	30%
205	2199	1060	30%
131	2199	1060	30%
112	0399	1060	10%

Knowledge Area
112 - Watershed Protection and Management; 205 - Plant Management Systems; 203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants; 131 - Alternative Uses of Land;

Subject Of Investigation
2199 - Ornamentals and turf, general/other; 0399 - Watersheds and river basins, general;

Field Of Science
1060 - Biology (whole systems);

Keywords

green roofs

plant evaluations

succulents

carbon sequestration

stormwater manangement

energy conservation

urban development

Goals / Objectives
The objectives of this research program are to: 1) Evaluate potential green roof plant species for propagation method, rate of establishment, nutrient requirements, drought resistance, heat and cold tolerance, plant competition, ability to exclude invasive weeds, and survival and persistence. Includes evaluating mixed plant communities and succession over time. 2) Quantify carbon sequestration potential (both quantity and timeframe) of a typical extensive green roof and to evaluate the effect of species on carbon flux. 3) Evaluate influence of vegetation on roof thermal properties, heat flux, and energy conservation. 4) Quantify differences in water retention among roof vegetation types, substrate depths, and roof slopes. 5) Public relations: provide visibility regarding green roofs.

Project Methods
Several studies will be conducted to help predict essential design requirements for green roof construction and implementation. Experiments will be conducted on the roof of the Plant and Soil Sciences Building (PSSB), on the roof of the Communication Arts Building (CAB), and on 48 roof platforms at the Horticulture Teaching and Research Center (HTRC). Long-term plant evaluations will be conducted at all three locations for such characteristics as propagation success, rate of establishment, growth and survival, groundcover density and ability to exclude invasive weeds, competition among species, persistence over several years, cold tolerance, and drought resistance. Initially, image analysis software will be utilized to analyze digital photographs to determine the percentage of plant canopy that can be attributed to each individual species. After initial growth rates are established and plants begin to fill in the platforms, a point-frame transect will be used to measure leaf area index in order to evaluate plant competition. A study to quantify the carbon sequestration potential will be conducted on the PSSB. After initial soil samples are analyzed, multiple plots covered with a single species of Sedum (S. acre, S. album, S. kamtshaticum, or S. spurium) or a substrate only treatment, will be sampled and carbon analysis will be performed on above-ground biomass, below-ground biomass (roots), and soil carbon content several times per season over a period of three years. Total carbon concentration will be determined by using a Carlo Erba NA1500 Series 2 N/C/S analyzer. Thermal properties are being determined on the PSSB which is divided into two experimental sections, one with a green roof and the other as a standard ballasted commercial roof. Both sides are instrumented with sensors to record heat flux, soil moisture, and temperatures at various points in the roof profile. Data is recorded every five minutes, 24 hours a day using a Campbell Scientific CR10X datalogger. Data is being analyzed by John Lloyd in Mechanical Engineering to develop a model to predict energy savings. Stormwater management studies will continue to be conducted at HTRC to quantify differences in water retention among combinations of vegetation types, roof slopes, and substrate compositions and depths. Tipping bucket rain gauges are mounted under the drain of each platform to quantify runoff. Data from the tipping bucket rain gauges and tripod weather station will be collected every five minutes, 24 hours a day using a datalogger.

Progress 11/01/08 to 10/31/13

Outputs
Target Audience: The target audiences include industry members such as the growers of nursery crops, substrate suppliers, landscape architects, landscape contractors, architects, and engineers. Also, it is aimed to provide scientific data and educate government officials and public policy makers on the environmental, economic, and social benefits that green roofs can provide. In addition, it provides knowledge for fellow researchers as well as educates the general public. Results will be reported in peer-reviewed journals and in trade publications, presented at scientific and industry gatherings, taught in a specific MSU course on green roofs, and posted on our website (www.hrt.msu.edu/greenroof). In addition, as a member of the E06.71 sustainability committee of ASTM International and the Research Committee of GRHC, information gained will be included in future standards. It will ultimately contribute to educational products that promote the contributions of the green industry to environmental stewardship and sustainability. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Six graduate students have completed their degrees (2 PhD’s) Mentored three visiting scholars: Mert Eksi, Istanbul University, Turkey (April 2013 – March 2014), Rafael Fernández Cañero, University of Seville, Spain (June 2013 – August 2013), and Hamidah Ahmad, Universiti Teknologi Malaysia, West Malaysia (September – December 2013). Member of team that developed a professional training course, Green Roofs 401 Plants and Growing Medium, for Green Roof Professional Certification. Worked with university researchers at Beijing Forestry University, government officials, and industry representatives to train them on how to implement green roofs in China (2010). Other international training was presented in Finland (2012) and France (2013). Guest lectures on green roofs in MSU classes: BE 482 - Diffuse-Source Pollution Engineering (4-18-13); ESA 200 - Intro Environmental Studies (2010, 2011, 2013); FW 410 - Upland Ecosystem Management (2010, 2011, 2012, 2013); HRT 111 - Landscape Design (2010); HRT 203 - Principles of Horticulture (2009, 2010, 2011, 2012, 2013); HRT 415 - Native Plants Landscape Restoration (2012); HRT 417 (Sustainable Sites Environmental Landscape Practicum (2010, 2011); HRT/LA 883 - Environ Design Seminar (2009, 2012, 2013); LA 492 - Senior Research Seminar (2009, 2010); and UP 400/800 - Urban Planning (2009). Included the topic of green roofs in my own class for non-majors, HRT 102 – Plants for Food, Fun, and Profit (2012, 2013), and am developing a new one-credit course HRT 460 – Green Roofs and Walls to be taught for the first time during Fall 2013. Worked with students in the Environmental Science Club at Okemos High School to install a green roof on their Recycling Center (2009). How have the results been disseminated to communities of interest? Results have been reported in peer-reviewed journals and in trade publications such as The Michigan Landscape and Living Architecture Monitor and presented at scientific and industry gatherings of Green Roofs for Healthy Cities (GRHC), the World Green Infrastructure Network, American Society for Horticultural Science (ASHS), American Society of Landscape Architects (ASLA), and MNLA, as well as many lay groups. A summary of research results are published on the MSU Green Roof Research Program website (www.hrt.msu.edu/greenroof). In addition, as a member of the E06.71 sustainability committee of ASTM International and the Green roof media committee of GRHC, information gained will be included in future standards. It has been included in course literature for the Green Roof professional Certification administered by GRHC. In addition, past, present, and future findings from our green roof research program will be taught in a new interdepartmental course HRT 460 - Green Roofs and Walls (subject to university approval) that will be cross listed across Horticulture, Planning Design and Construction, Geography, Fisheries and Wildlife, Mechanical Engineering, and Civil and Environmental Engineering. The new course request has been submitted and if approved it will taught for the first time during Fall Semester 2014. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Green roofs entail growing plants on rooftops and may provide many economic and environmental benefits. Furthermore, the construction and maintenance of green roofs provide business opportunities for green industry members while addressing issues of environmental stewardship. Several studies were conducted to evaluate potential plant species, quantify carbon sequestration, measure the effect of green roofs on heat flux through the building envelope, and to measure stormwater retention. Several species have been identified that are suitable for use on shallow green roofs. A 6 cm sedum based extensive green roof reduced average heat flux through the building envelope by 13% in winter and 176% during the summer. Results suggest the potential for major energy savings for an individual building, but also a reduction in carbon emissions from power plants because of reduced energy consumption. Green roofs also retain stormwater and release it over a longer period of time, thus reducing the need to invest in larger municipal stormwater systems. Increased awareness and quantitative data such as ours helps make the case for investing in green roofs. The potential for economic and environmental impact is outstanding considering that the market consists of all existing and future buildings. According to Green Roofs for Healthy Cities, the green roof industry in North America grew 115% during 2011. Business opportunities exist in the green roof industry and the MSU green roof research program has directly resulted in two startup companies. A former faculty member that helped start the program established XeroFlor America (www.xeroflora.com) and a former graduate student recently started his own green roof company, Advanced Green Architecture (www.agagreen.com). Objective 1: Evaluate potential green roof plant species. Several studies were conducted in roof platforms and on a third-story rooftop to quantify the effect of solar radiation and substrate depth on several U.S. native and non-native species for potential use on extensive green roofs. One study followed the succession of 25 succulents (various species of Graptopetalum, Phedimus, Rhodiola, and Sedum) grown at three media depths (2.5, 5.0, and 7.5 cm) over the course of seven years. Absolute cover was determined using a point-frame transect every two weeks during the first three growing seasons and monthly during years four through seven to measure community composition and change. At the 7.5 cm depth, 22 species were present at the end of the first growing season, but these numbers were reduced to 13, 8, and 7 after two, three, and five years, respectively. Similar results occurred at the shallower depths except that the number of species was reduced at a faster pace. Plants that initially survive may eventually experience reduced coverage or disappear completely due to competition, variability in climate, and other factors. These factors should all be considered during the design and planning phase of a green roof. Objective 2: Quantify carbon sequestration potential (both quantity and timeframe) of a typical extensive green roof and to evaluate the effect of species on carbon flux. One potential benefit of green roofs is their potential to mitigate climate change. By sequestering carbon in plants and soils and by lowering demand for heating and air conditioning use, less carbon dioxide will be released from power plants and furnaces. A study was conducted on the roof of the Plant and Soil Sciences Bldg. where 20 plots were established with a substrate depth of 6.0 cm. In addition to a substrate only control, plots were sown with a single species of Sedum (S. acre, S. album, S. kamtshaticum, or S. spurium). Plant material and substrate were harvested seven times across two growing seasons. Results at the end of the second year showed that above- and below-ground plant material storage varied by species with a total of 375 g C m2. If all of the commercial and industrial roofs in metropolitan Detroit (14,734 hectares) were covered with vegetation in a design similar to this study and sequestered 375 g C m2 of green roof, 55,252 metric tons of carbon could be sequestered in the plants and substrates alone (not including avoided emissions). While these figures depend on climate and green roof design, they nonetheless represent a small but significant potential for sequestering carbon in urban environments. Objective 3: Evaluate influence of vegetation on roof thermal properties, heat flux, and energy conservation. Green roofs, or vegetated roofs, can reduce heat flux magnitude through a building envelope as a result of insulation provided by the growing medium, shading from the plant canopy, and transpirational cooling provided by the plants. This study compared the heat flux properties of a green roof relative to a conventional gravel-ballasted roof on the PSSB. Temperature, heat flux, soil moisture, and ambient weather conditions were recorded over a period of two years using a datalogger. The greatest impact was during the summer as the green roof reduced heat flux through the building envelope by an average of 13% in winter and 167% during summer. In terms of temperature, maximum and minimum average monthly temperatures over the course of the year were consistently more extreme for the gravel ballasted roof than the green roof and the gravel roof was up to 20 C warmer during the summer. For all variables measured, the gravel roof generally exhibited larger fluctuations than the green roof. Results suggest the potential for energy use reductions for green roofed buildings with associated monetary savings but also environmental benefits as carbon emissions are reduced by lower energy consumption. The magnitude of these savings will influenced by many factors including climate, type of roof, the amount of insulation provided during building construction, growing media depth and composition, plant selection, and whether the roof is irrigated. Objective 4: Quantify differences in water retention among roof vegetation types, substrate depths, and roof slopes. Impervious surfaces, such as rooftops, parking lots, and roads, increase runoff and the potential for flooding. Green roof technologies, which entail growing plants on rooftops, are increasingly being used to alleviate stormwater runoff problems. To quantify the effect that roof slope has on green roof stormwater retention, runoff was analyzed from twelve extensive green roof platforms constructed at four slopes (2%, 7%, 15%, and 25%). Rain events were categorized as light (<2.0 mm), medium (2.0 – 10.0 mm), or heavy (>10.0 mm). Data demonstrated an average retention value of 80.8%. Mean retention was least at the 25% slope (76.4%) and greatest at the 2% slope (85.6%). In addition, runoff that did occur was delayed and distributed over a long period of time for all slopes. Curve numbers, a common method used by engineers to estimate stormwater runoff for an area, ranged from 84 to 90, and are all lower than a conventional roof curve number of 98, indicating that these greened slopes reduced runoff compared to traditional roofs. Objective 5: Public relations: provide visibility regarding green roofs. Results from our research were published in peer-reviewed scientific journals and in proceedings of conferences. Numerous oral presentations were made at conferences of Green Roofs for Healthy Cities and the US Green Building Council, as well as other industry organizations. Other presentations included national interviews on NPR, Discovery, MSNBC, and Fox News regarding green roof carbon sequestration and guest lectures to classes in Landscape Architecture, Environmental Studies, Horticulture, and Urban Planning. In addition, we were involved in the design and implementation of the world’s largest green roof (10.4 acres) on the Ford Motor Company assembly plant in Dearborn, as well as 7 green roofs on the MSU campus.

Publications

• Type: Journal Articles Status: Published Year Published: 2011 Citation: Whittinghill, L.J., Rowe, D.B. 2011. Salt tolerance of common green roof and green wall plants. Urban Ecosystems 14(4):783-794. (http://dx.doi.org/10.1007/s11252-011-0169-4).
• Type: Book Chapters Status: Published Year Published: 2010 Citation: Rowe, D. B., Getter, K.L. 2010. Green roofs and roof gardens. p. 391-412. In: J. Aitkenhead-Peterson and A. Volder (ed.). Urban Ecosystems Ecology. Agron. Monogr. 55. American Society of Agronomy. Crop Science Society of America. Soil Science Society of America, Madison, WI.
• Type: Journal Articles Status: Published Year Published: 2010 Citation: Rowe, D.B. 2010. Green roofs as a means of pollution abatement. Environmental Pollution 159(8-9):2100-2110. (http://dx.doi.org/10.1016/j.envpol.2010.10.029).
• Type: Journal Articles Status: Published Year Published: 2009 Citation: Getter, K.L., Rowe, D.B., Robertson, G.P., Cregg, B.M., Andresen, J.A. 2009. Carbon sequestration potential of extensive green roofs. Environmental Science and Technology 43:7564-7570.
• Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Whittinghill, L.J., Rowe, D.B. 2012. Vegetable production on extensive green roofs. Proc. of 10th North American Green Roof Conference: Cities Alive, Chicago, IL. 17-20 October, 2012.
• Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Krogulecki, K., Westphal, J., Rowe, B., Khire, M. 2012. Effects of vegetation on green roof runoff water quality. Proc. of World green Roof Congress, Copenhagen. 19-20 September, 2012.
• Type: Conference Papers and Presentations Status: Published Year Published: 2011 Citation: Rowe, D.B., Getter, K.A., Durhman, A.K. 2011. Importance of long-term plant evaluations for extensive green roofs. Proc. of 9th North American Green Roof Conference: Cities Alive, Philadelphia, PA.
• Type: Conference Papers and Presentations Status: Published Year Published: 2010 Citation: Rugh, C.L., Liu, K.Y., Getter, K.L., Rowe, D.B. 2010. Seasonal biomass and sequestration flux. Proc. of 8th North American Green Roof Conference: Cities Alive, Vancouver, B.C. 30 Nov to 3 Dec, 2010.
• Type: Journal Articles Status: Published Year Published: 2009 Citation: Getter, K.L., Rowe, D.B, Cregg, B.M. 2009. Solar radiation intensity influences extensive green roof plant communities. Urban Forestry and Urban Greening 8:269-281.
• Type: Journal Articles Status: Published Year Published: 2009 Citation: Getter, K.L., Rowe, D.B. 2009. Substrate depth influences sedum plant community on a green roof. HortScience 44:401-407.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Whittinghill, L.J., Rowe, D.B., Schutzki, R., Cregg, B.M. 2013. Quantifying carbon sequestration of green roof of varying complexity. Proc. of 11th North American Green Roof Conference: Cities Alive, San Francisco, CA. 23-26 October, 2013.
• Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Rowe, D.B., Kolp, M., Getter, K., Duck, M. 2012. Comparison of water use efficiency of overhead, drip, and sub-irrigation for green roofs. Proc. of 10th North American Green Roof Conference: Cities Alive, Chicago, IL. 17-20 October, 2012.
• Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Sutton, R., Rowe, B., MacDonagh, P., Acomb, G., Lambrinos, J., Hawke, R. 2012. New plant performance for 21st century green roof ecosystems. Proc. of 10th North American Green Roof Conference: Cities Alive, Chicago, IL. 17-20 October, 2012.
• Type: Conference Papers and Presentations Status: Published Year Published: 2010 Citation: Whittinghill, L.J., Rowe, D.B. 2010. Salt tolerance of common green roof and green wall plants. Proc. of 8th North American Green Roof Conference: Cities Alive, Vancouver, B.C. 30 Nov to 3 Dec, 2010.
• Type: Conference Papers and Presentations Status: Published Year Published: 2009 Citation: Getter, K.L., Rowe, D.B. 2009. Carbon sequestration potential of extensive green roofs. Proc. of 7th North American Green Roof Conference: Greening Rooftops for Sustainable Communities, Atlanta, GA. 3-5 June 2009.
• Type: Theses/Dissertations Status: Published Year Published: 2012 Citation: Cronk, Erik. 2012. Stormwater mitigating effects of steep green roof systems on receiving urban ecosystems Masters in Environmental Design, Department of Landscape Architecture, Michigan State University, East Lansing (committee member).
• Type: Theses/Dissertations Status: Published Year Published: 2009 Citation: Getter, K.L. 2009. Extensive green roofs: Carbon sequestration potential and species evaluations. PhD Dissertation, Department of Horticulture, Michigan State University, East Lansing (major advisor).
• Type: Theses/Dissertations Status: Published Year Published: 2012 Citation: Eaken, Carly. 2012. Assessing wildlife habitat contributions of green roofs in urban landscapes in Michigan and Illinois, USA: Measuring avian community response to green roof factors. MS, Department of Fisheries and Wildlife, Michigan State University, East Lansing (committee member).
• Type: Theses/Dissertations Status: Published Year Published: 2012 Citation: Whittinghill, Leigh. 2012. Vegetable production using green roof technology and the potential impacts on the benefits provided by conventional green roofs. PhD Dissertation, Department of Horticulture, Michigan State University, East Lansing (major advisor).
• Type: Theses/Dissertations Status: Published Year Published: 2011 Citation: Monsma, Jeremy. 2011. Ecological succession of green roof plants with emphasis on urban wildlife habitat for insect populations. Masters in Environmental Design, Department of Landscape Architecture, Michigan State University, East Lansing (committee member).
• Type: Websites Status: Published Year Published: 2009 Citation: Green roof research at Michigan State University, 2009, www.hrt.msu.edu/greenroof/
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Whittinghill, L.J., Rowe, D.B., Cregg, B.M. 2013. Evaluation of vegetable production on extensive green roofs. Agroecology and Sustainable Food Systems 37(4): 465-484. (http://dx.doi.org/10.1080/21683565.2012.756847).
• Type: Journal Articles Status: Published Year Published: 2012 Citation: Rowe, D.B., Getter, K.L., Durhman, A.K. 2012. Effect of green roof media depth on Crassulacean plant succession over seven years. Landscape and Urban Planning 104(3-4):310-319. (online: http://dx.doi.org/10.1016/j.landurbplan.2011.11.010).
• Type: Journal Articles Status: Published Year Published: 2012 Citation: Whittinghill, L.J., Rowe, D.B. 2012. The role of green roof technology in urban agriculture. Renewable Agriculture and Food Systems 27(4):314-322. (http://dx.doi.org/10.1017/S174217051100038X).
• Type: Journal Articles Status: Published Year Published: 2011 Citation: Getter, K.L., Rowe, D.B., Andresen, J.A., Wichman, I.S. 2011. Seasonal heat flux properties of an extensive green roof in a Midwestern U.S. climate. Energy and Buildings 43:3548-3557. (http://dx.doi.org/10.1016/j.enbuild.2011.09.018).

Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: Green roofs or vegetated roofs entail growing plants on rooftops, providing many benefits such as improved stormwater management, energy conservation, mitigation of the urban heat island, increased longevity of roofing membranes, carbon sequestration, reduction in noise and air pollution, improved aesthetics, and provide a site for urban agriculture. Another benefit of green roofs is their potential to mitigate climate change. By sequestering carbon in plants and soils and by lowering demand for heating and air conditioning use, less carbon dioxide will be released from power plants and furnaces. Previous studies conducted by Getter and Rowe (2008, 2009) determined that a sedum based roof with a substrate depth of 6.0 cm sequestered 375 g C m2 of green roof. Increasing substrate depth and the complexity of the planted landscape system would likely increase this value. Therefore, another study was initiated to quantify the carbon storage potential of 12 landscape systems with increasing levels of complexity ranging from sedum to woody shrubs over the course of three years. Three of the landscapes growing at ground level were duplicated with identical plants on roof platforms in green roof media at a depth of 10 cm. Soil or substrate samples were analyzed prior to planting in 2009 and soil/substrate, below- and above-ground biomass were analyzed at the end of the 2010 and 2011 growing seasons. As expected, landscape systems containing more woody structures, such as the three shrub systems and the herbaceous perennials and grasses had higher carbon content than other landscape systems. Carbon storage on the various green roof systems ranged from 68 kg m2 for a mixture of herbaceous perennials and grasses down to 7 kg m2 for a typical sedum-based extensive green roof. The Sedum and prairie green roofs contained less carbon than their counterpart in-ground landscape systems, suggesting that although green roofs do sequester a small amount of carbon, greater benefit can be achieved in ground level landscape systems. Ornamental landscapes have good potential for carbon sequestration but management practices can affect their net carbon sequestration and the permanence of the carbon sequestered. Additional studies are ongoing to compare irrigation methods and evaluate the potential for growing vegetables on extensive green roofs. Findings from our research have been published in peer-reviewed scientific journals and in proceedings of conferences. Likewise, results of this study will be published and presented at meetings. During 2012, sixteen oral presentations were made at conferences such as Green Roofs for Healthy Cities, US Green Building Council, Ecological Society of America, Mid-Atlantic Green Roof Science and Technology Symposium, Great Lakes High Performance Building Conference, International Scientific Meeting for Green Roof Research, Helsinki, Finland, and at the University of Sheffield, U.K, as well as numerous presentations to lay audiences and as a guest lecturer in MSU classes. In addition, I have developed and maintained a website covering my research program (www.hrt.msu.edu/greenroof). PARTICIPANTS: Jeff Andresen has been involved primarily as a member of graduate student committees, with experimental design, and for his expertise with monitoring equipment. John Lloyd is a heat flux expert in Mechanical Engineering who is now retired and no longer working on the project. Indrek Wichman from Mechanical Engineering has assumed this role. Krisitn Getter (PhD), Leigh Whittinghill (PhD), and Angela Durhman are three of my former graduate students. Kristin is currently a faculty member in the same department. The following companies or professional organizations have contributed direct support or in-kind support: Behrens Systementwicklung, Grosse Ippener, Germany; Ford Motor Company, Dearborn, MI; Green Roof Plants, Street, MD; Hortech, Inc., Spring Lake, MI; LiveRoof, LLC, Spring Lake, MI; and XeroFlor America, LLC, Durham, NC. Training of students is occurring in my classes HRT 492 Undergraduate Research and HRT 413 Sustainable Landscape Practices. As a member of ASTM International subcommittee on green roof systems, much of our research results are being incorporated into ASTM standards. Also as a member of Green Roofs for Healthy Cities Green Roof Professional Education Committee, information is being incorporated into a certification course we are developing on plant and growing media. TARGET AUDIENCES: Professionals involved with the green roof industry and government officials that develop policy for environmental stewardship. This includes green roof designers, landscape architects, architects, roofing contractors, green roof manufacturers and suppliers, fellow researchers, students, and the general public. PROJECT MODIFICATIONS: Future emphasis will expand on urban food production and sustainable irrigation practices, as well as developing more sustainable light weight growing substrates.

Impacts
Landscape systems that sequestered the most carbon contained higher amounts of woody plant structures and higher plant biomass volumes, such as the three shrub landscape systems and the herbaceous perennial and grasses, native prairie mix, and ornamental green roofs. Two of the green roof landscape systems examined, sedum and prairie green roofs, did not sequester as much carbon as their counterpart in-ground landscape systems. This was likely due to differences in soil and substrate properties and the ability the landscape systems to reach 100% surface coverage. Even so, because of the deeper substrate depths in this study, the green roof landscape systems sequestered more carbon than shown by previous research (Getter and Rowe, 2009) and their use may reduce the payback period of carbon embodied in the green roof materials from 15 yrs to less than 3 yrs. This timeframe could be further condensed due to the reduction in energy consumption when a green roof is present. In a previous study conducted on our Plant and Soil Sciences Building, a 6 cm sedum based extensive green roof reduced average heat flux through the building envelope by 13% in winter and 176% during the summer. Results suggest the potential for major energy savings for an individual building, but also a reduction in carbon emissions from power plants because of reduced energy consumption. Additionally, climate change could even be impacted if the green roof technology were applied over large areas. Although this may be promising for the green roof industry, greater carbon sequestration can still be achieved on the ground and carbon sequestration will likely only be a secondary benefit of green roofs. The in-ground landscape systems also show promise for contributions to carbon sequestration with total carbon values similar to some reported in the literature for forests in the United States. Results of these studies are of use to green roof designers, engineers, and installation contractors, as well as government policy makers and may potentially be used to determine energy savings and in any carbon cap and trade program that may be adopted in the future. Findings from our green roof research program have already been utilized in the design and construction of the worlds largest green roof (10.4 acres) on the Ford Motor Company assembly plant in Dearborn, Michigan. The potential of green roofs for economic and environmental impact is outstanding considering that the market consists of all existing and future buildings.

Publications

• Rowe, D.B., Kolp, M., Getter, K., Duck, M. 2012. Comparison of water use efficiency of overhead, drip, and sub-irrigation for green roofs. Proc. of 10th North American Green Roof Conference: Cities Alive, Chicago, IL. 17-20 October, 2012.
• Rugh, C., Lui, K.Y., Rowe, D.B. 2012. Ford green roof: Ten years of dynamic stability. Proc. of 10th North American Green Roof Conference: Cities Alive, Chicago, IL. 17-20 October, 2012.
• Sutton, R., Rowe, B., MacDonagh, P., Acomb, G., Lambrinos, J., Hawke, R. 2012. New plant performance for 21st century green roof ecosystems. Proc. of 10th North American Green Roof Conference: Cities Alive, Chicago, IL. 17-20 October, 2012.
• Whittinghill, L.J., Rowe, D.B. 2012. Vegetable production on extensive green roofs. Proc. of 10th North American Green Roof Conference: Cities Alive, Chicago, IL. 17-20 October, 2012.
• Krogulecki, K., Westphal, J., Rowe, B., Khire, M. 2012. Effects of vegetation on green roof runoff water quality. Proc. of World Green Roof Congress, Copenhagen. 19-20 September, 2012.
• Rowe, D.B. 2012. Green roof substrate depth and composition studies on plant performance conducted at Michigan State University. Mid-Atlantic Green Roof Science and Technology Symposium, College Park, MD. 16-17 August, 2012.
• Warsaw, A.L., Fernandez, R.T., Kort, D.R., Cregg, B.M., Rowe, B., Vandervoort, C. 2012. Remediation of metalaxyl, trifluralin, and nitrate from nursery runoff using container-grown woody ornamentals and phytoremediation areas. Ecological Engineering 47:254-263.

Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: Green roofs or vegetated roofs entail growing plants on rooftops, providing many benefits such as improved stormwater management, energy conservation, mitigation of the urban heat island, increased longevity of roofing membranes, carbon sequestration, reduction in noise and air pollution, improved aesthetics, and provide a site for urban agriculture. Regarding energy, they are thought to reduce heat flux through a building envelope as a result of insulation provided by the substrate layer, shading from the plant canopy, and transpirational cooling provided by the plants. One study completed this year was the comparison of heat flux properties of a green roof relative to a conventional gravel-ballasted roof. A 325 m2 extensive green roof vegetated with several succulent species was installed on a portion of the Plant and Soil Sciences Building (PSSB). Temperature, heat flux, soil moisture, and ambient weather conditions were recorded over a period of two years using a datalogger. The gravel portion of the roof and the vegetative side of the roof each had three measurement stations, spaced 3.0 m apart. Each station had five thermocouples installed in the following profile locations: 1 m above the roof inside a non-aspirated solar radiation shield, on top of the media (or gravel), on top of the insulation, on top of the roofing membrane, and inside the building. In addition, a heat flow sensor was installed on top of the roof insulation at each measurement station. The sensor was deployed so that negative and positive readings would signify heat entering and leaving the building, respectively. Another benefit of green roofs is their potential to mitigate climate change. By sequestering carbon in plants and soils and by lowering demand for heating and air conditioning use, less carbon dioxide will be released from power plants and furnaces. Previous studies conducted by Getter and Rowe (2008, 2009) determined that a sedum based roof with a substrate depth of 6.0 cm sequestered 375 g C m2 of green roof. Increasing substrate depth and the complexity of the planted landscape system would likely increase this value. Therefore, we are continuing to collect data on a study that was initiated to compare eleven landscape systems with increasing levels of complexity ranging from sedum to woody shrubs over the course of three years. Three of the landscapes growing at ground level are duplicated with identical plants on roof platforms in green roof media. Findings from our research have been published in peer-reviewed scientific journals and in proceedings of conferences. Likewise, results of this study will be published and presented at meetings. During 2011, seven oral presentations were made at conferences such as Green Roofs for Healthy Cities, Ecological Society of America, the Central Environmental Nursery Trade Show at Ohio State, and to groups such as the Lansing Boys and Girls Clubs. Other presentations included five guest lectures to MSU classes in Landscape Architecture, Horticulture, and Fisheries and Wildlife. In addition, I have developed and maintained a website covering my research program (www.hrt.msu.edu/greenroof). PARTICIPANTS: Jeff Andresen has been involved primarily as a member of graduate student committees, with experimental design, and for his expertise with monitoring equipment. John Lloyd is a heat flux expert in Mechanical Engineering who is now retired and no longer working on the project. Indrek Wichman from Mechanical Engineering has assumed this role. Kristin Getter and Angela Durhman are two of my former graduate students. Leigh Whittinghill is my current PhD graduate student. The following companies or professional organizations have contributed direct support or in-kind support: Behrens Systementwicklung, Grosse Ippener, Germany; Ford Motor Company, Dearborn, MI; Green Roof Plants, Street, MD; Hortech, Inc., Spring Lake, MI; LiveRoof, LLC, Spring Lake, MI; and XeroFlor America, LLC, Durham, NC. Training of students is occurring in my classes HRT 492 Undergraduate Research and HRT 413 Sustainable Landscape Practices. As a member of ASTM International subcommittee on green roof systems, much of our research results are being incorporated into ASTM standards. Also as a member of Green Roofs for Healthy Cities Green Roof Professional Education Committee, information is being incorporated into a certification course we are developing on plant and growing media. TARGET AUDIENCES: Professionals involved with the green roof industry and government officials that develop policy for environmental stewardship. This includes green roof designers, landscape architects, architects, roofing contractors, green roof manufacturers and suppliers, fellow researchers, students, and the general public. PROJECT MODIFICATIONS: Future emphasis will expand on carbon sequestration and include urban food production and sustainable irrigation practices.

Impacts
The green roof portion of the PSSB reduced heat flux through the building envelope. During the autumn season, green roof temperatures were consistently 5 C lower than the corresponding gravel roof temperatures. However, during chilly moist conditions, heat flux leaving the building is lower for the green roof than the gravel roof. Temperatures in the top of the insulation layer were much more variable for both green roof and gravel roof on winter days with no snow cover than on days with snow cover. Spring season trends were similar to those in autumn. Peak temperature differences between the gravel and green roof were larger in the summer than other seasons (sometimes as much as 20 C). Over the course of a year, maximum and minimum average monthly gravel roof temperatures were consistently more extreme than those on the green roof. The green roof reduced the average heat flux 13% in winter and 176% during the summer. The study demonstrates the role that vegetation on the roof plays for roof temperatures and heat flux in a Midwestern U.S. climate. The transition seasons (autumn and spring) showed similar responses between the green and gravel roof, as well as the winter season when there is snow cover on both roofs. The greatest difference between gravel and green roofs is seen in this study during the summer season, where the gravel roof cumulative monthly heat flux values show a net heat gain into the building while the green roof showed a cooling effect on the building. This study also suggests and agrees with what others have found in that heat transfer and thermal differences between green roofs and gravel roofs appear to be controlled in large part by solar radiation, ambient outside temperature, and volumetric moisture content of the substrate. The presence of snow was also a controlling factor. In addition, for all variables measured, the gravel roof almost always had larger fluctuations than the green roof, likely due to the material differences of the roof covering. Results suggest the potential for major energy savings for an individual building resulting not only in monetary savings but also environmental benefits as carbon emissions are protected by less energy consumption. Additionally, climate change could even be impacted if the green roof technology were applied over large areas. Future research should compare these energy savings and thermal properties to a similarly designed green roof in this climate to a non-inverted roof. Results of these studies are of use to green roof designers, engineers, and installation contractors, as well as government policy makers and may potentially be used to determine energy savings and in any carbon cap and trade program that may be adopted in the future. Findings from our green roof research program have already been utilized in the design and construction of the worlds largest green roof (10.4 acres) on the Ford Motor Company assembly plant in Dearborn, Michigan. The potential of green roofs for economic and environmental impact is outstanding considering that the market consists of all existing and future buildings.

Publications

• Getter, K.L., Rowe, D.B., Andresen, J.A., Wichman, I.S. 2011. Seasonal heat flux properties of an extensive green roof in a Midwestern U.S. climate. Energy and Buildings 43:3548-3557. (online:http://dx.doi.org/10.1016/j.enbuild.2011.09.018)
• Rowe, D.B., Getter, K.L., Durhman, A.K. 2011. Effect of green roof media depth on Crassulacean plant succession over seven years. Landscape and Urban Planning (In press) (online:http://dx.doi.org/10.1016/j.landurbplan.2011.11.010).
• Whittinghill, L.J., Rowe, D.B. 2011. The role of green roof technology in urban agriculture. Renewable Agriculture and Food Systems (In press) (online:http://dx.doi.org/10.1017/S174217051100038X)
• Rowe, D.B., Getter, K.A., Durhman, A.K. 2011. Importance of long-term plant evaluations for extensive green roofs. Proc. of 9th North American Green Roof Conference: Cities Alive, Philadelphia, PA.

Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: Green roofs entail growing plants on rooftops, providing many benefits such as improved stormwater management, energy conservation, mitigation of the urban heat island effect, increased longevity of roofing membranes, reduction in noise and air pollution, and improved aesthetics. Another benefit is their potential to mitigate climate change. By sequestering carbon in plants and soils and by lowering demand for heating and air conditioning use, less carbon dioxide will be released from power plants and furnaces. Previous studies conducted by Getter and Rowe (2008, 2009) on the roof of the Plant and Soil Sciences Building determined that a sedum based roof with a substrate depth of 6.0 cm sequestered 375 g C m2 of green roof. Increasing substrate depth and the complexity of the planted landscape system would likely increase this value. Therefore, another study was initiated to compare eleven landscape systems with increasing levels of complexity ranging from sedum to woody shrubs over the course of three years. Three of the landscapes growing at ground level are duplicated with identical plants on roof platforms in green roof media to compare differences between natural and engineered systems. At the present time, initial soil samples and samples of top growth, roots, and soil have been collected and prepared for carbon analysis. This study will quantify the magnitude and timeframe of these systems as potential carbon sinks and estimate the reduction in carbon emissions from power plants due to energy savings from green roofs. The succulent garden and green roof were sown with common green roof species of sedum which have previously been examined for carbon sequestration potential on an individual basis. The mulched herbaceous perennial beds consist of Miscanthus sinensis, Perovskia atriplicifolia, Echinacea purpurea, Hemerocallis, and Rudbeckia speciosa planted from one gallon containers. The native prairie was sown from a seed mix of 22 herbaceous perennials and five grasses. The other five landscape systems include turf grass, groundcovers, deciduous shrubs, narrow leaf evergreen shrubs, broad leaf evergreen shrubs. Findings from our research have been published in peer-reviewed scientific journals and in proceedings of conferences. Likewise, results of this study will be published and presented at meetings. During 2010, seventeen oral presentations were made at conferences such as Green Roofs for Healthy Cities and the Ecological Society of America as well as industry organizations in the United States and China. Other presentations included seven guest lectures to MSU classes in Landscape Architecture, Environmental Studies, Horticulture, and Fisheries and Wildlife. In addition, I have developed and maintained a website covering my research program (www.hrt.msu.edu/greenroof). PARTICIPANTS: Jeff Andresen has been involved primarily as a member of graduate student committees, with experimental design, and for his expertise with monitoring equipment. John Lloyd is a heat flux expert in Mechanical Engineering who is now retired and no longer working on the project. Kristin Getter is a recently graduated PhD student and Leigh Whittinghill is a current graduate student. Clayton Rugh and Karen Lui are both PhD scientists employed by XeroFlor America.The following companies or professional organizations have contributed direct support or in-kind support: Behrens Systementwicklung, Grosse Ippener, Germany; Ford Motor Company, Dearborn, MI; Green Roof Plants, Street, MD; Hortech, Inc., Spring Lake, MI; LiveRoof, LLC, Spring Lake, MI; and XeroFlor America, LLC, Durham, NC. Training of students is occurring in my classes HRT 492 Undergraduate Research and HRT 413 Sustainable Landscape Practices. As a member of ASTM International subcommittee on green roof systems, much of our research results are being incorporated into ASTM standards. Also as a member of Green Roofs for Healthy Cities Green Roof Professional Education Committee, information is being incorporated into a certification course we are developing on plant and growing media. TARGET AUDIENCES: Professionals involved with the green roof industry and government officials that develop policy for environmental stewardship. This includes green roof designers, landscape architects, architects, roofing contractors, green roof manufacturers and suppliers, fellow researchers, students, and the general public. PROJECT MODIFICATIONS: Future emphasis will expand on carbon sequestration and include urban food production.

Impacts
Green roofs have the potential to mitigate climate change by sequestering carbon on the roof and by lowering demand for heating and air conditioning use resulting in less carbon dioxide released from power plants and furnaces. Based on a model supported by the U.S. Department of Energy of a generic building with a 2000 m2 green roof, annual energy savings would range from 27.2 to 30.7 GJ of electricity and 9.5 to 38.6 GJ of natural gas, depending on climate and green roof design. When considering the national averages of CO2 produced for generating electricity and burning natural gas, these figures translate to 637 to 719 g C per square meter of green roof in electricity and 65 to 266 g C per square meter of green roof in natural gas each year. Another 25% reduction in electricity use may additionally occur due to indirect heat island reduction achieved from large-scale green roof implementation throughout an urban area. Results of these studies are of use to green roof designers, engineers, and installation contractors and may potentially be used in any carbon cap and trade program that may be adopted in the future. Findings from our green roof research program have already been utilized in the design and construction of the worlds largest green roof (10.4 acres) on the Ford Motor Company assembly plant in Dearborn, Michigan. The potential of green roofs for economic and environmental impact is outstanding considering that the market consists of all existing and future buildings.

Publications

• Rowe, D.B. 2010. Green roofs as a means of pollution abatement. Environmental Pollution (Currently online) doi:10.1016/j.envpol.2010.10.029.
• Rowe, D. B., Getter, K.L. 2010. Green roofs and roof gardens. p. 391-412. In: J. Aitkenhead-Peterson and A. Volder (ed.). Urban Ecosystems Ecology. Agron. Monogr. 55. American Society of Agronomy. Crop Science Society of America. Soil Science Society of America, Madison, WI.
• Rugh, C.L., Liu, K.Y., Getter, K.L., Rowe, D.B. 2010. Seasonal biomass and sequestration flux. Proc. of 8th North American Green Roof Conference: Cities Alive, Vancouver, B.C. 30 Nov to 3 Dec, 2010. The Cardinal Group, Toronto.
• Whittinghill, L.J., Rowe, D.B. 2010. Salt tolerance of common green roof and green wall plants. Proc. of 8th North American Green Roof Conference: Cities Alive, Vancouver, B.C. 30 Nov to 3 Dec, 2010. The Cardinal Group, Toronto.

Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: Green roofs entail growing plants on rooftops, providing many benefits such as improved stormwater management, energy conservation, mitigation of the urban heat island effect, increased longevity of roofing membranes, reduction in noise and air pollution, and improved aesthetics. Another benefit is their potential to mitigate climate change. By sequestering carbon in plants and soils and by lowering demand for heating and air conditioning use, less carbon dioxide will be released from power plants and furnaces. A study was conducted on a roof in East Lansing, MI, where 20 plots were established in April 2007 with a substrate depth of 6.0 cm. In addition to a substrate only control, plots were sown with a single species of Sedum (S. acre, S. album, S. kamtshaticum, or S. spurium). Plant material and substrate were harvested seven times across two growing seasons. Results at the end of the second year showed that above-ground plant material storage varied by species, ranging from 64 g C m2 (S. acre) to 239 g C m2 (S. album), with an average of 168 g C m2. Below-ground biomass ranged from 37 g C m2 (S. acre) to 185 g C m2 (S. kamtschaticum) and averaged 107 g C m2. Substrate carbon content averaged 913 g C m2, with no species effect, which represents a sequestration rate of 100 g C m2 over the 2 years of this study. If all of the commercial and industrial roofs in metropolitan Detroit (14,734 hectares) were covered with vegetation in a design similar to this study and sequestered 375 g C m2 of green roof, 55,252 metric tons of carbon could be sequestered in the plants and substrates alone (not including avoided emissions). This is similar to removing more than 10,000 mid-sized SUV or trucks off the road for a year. While these figures depend on climate and green roof design, they nonetheless represent a small but significant potential for sequestering carbon in urban environments. While the embodied energy in the initial green roof system is greater than what is stored in the substrate and plant biomass at any given time, the emissions avoided due to energy savings should pay for those costs in time. When considering the greenhouse gas potential for generating electricity and burning natural gas, these figures translate to 702 g C per square meter of green roof in electricity and natural gas savings combined per year. Findings from our research were published in peer-reviewed scientific journals and in proceedings of conferences. Sixteen oral presentations were made at conferences of Green Roofs for Healthy Cities and the US Green Building Council, as well as other industry organizations. Other presentations included national interviews on NPR, Discovery, MSNBC, and Fox News regarding green roof carbon sequestration and guest lectures to classes in Landscape Architecture, Environmental Studies, Horticulture, and Urban Planning. In addition, I developed and maintain a website covering my research program www.hrt.msu.edu/greenroof that had over 25,000 hits during 2009. PARTICIPANTS: Jeff Andresen has been involved primarily as a member of graduate student committees, with experimental design, and for his expertise with monitoring equipment. John Lloyd is a heat flux expert in Mechanical Engineering working on the energy data. Kristin Getter is a recently graduated PhD student and Leigh Whittinghill is a current graduate student. The following companies or professional organizations have contributed direct support or in-kind support: Behrens Systementwicklung, Grosse Ippener, Germany; Ford Motor Company, Dearborn, MI; Green Roof Plants, Street, MD; Hortech, Inc., Spring Lake, MI; LiveRoof, LLC, Spring Lake, MI; and XeroFlor America, LLC, Durham, NC. Training of students is occurring in my classes HRT 492 Undergraduate Research and HRT 413 Sustainable Landscape Practices. As a member of ASTM International subcommittee on green roof systems, much of our research results are being incorporated into ASTM standards. Also as a member of Green Roofs for Healthy Cities Green Roof Professional Education Committee, information is being incorporated into a certification course we are developing on plant and growing media. TARGET AUDIENCES: Professionals involved with the green roof industry and government officials that develop policy for environmental stewardship. This includes green roof designers, landscape architects, architects, roofing contractors, green roof manufacturers and suppliers, fellow researchers, students, and the general public. PROJECT MODIFICATIONS: Future emphasis will expand on carbon sequestration and include urban food production.

Impacts
Green roofs have the potential to mitigate climate change by sequestering carbon on the roof and by lowering demand for heating and air conditioning use resulting in less carbon dioxide released from power plants and furnaces. Based on a model supported by the U.S. Department of Energy of a generic building with a 2000 m2 green roof, annual energy savings would range from 27.2 to 30.7 GJ of electricity and 9.5 to 38.6 GJ of natural gas, depending on climate and green roof design. When considering the national averages of CO2 produced for generating electricity and burning natural gas, these figures translate to 637 to 719 g C per square meter of green roof in electricity and 65 to 266 g C per square meter of green roof in natural gas each year. Another 25% reduction in electricity use may additionally occur due to indirect heat island reduction achieved from large-scale green roof implementation throughout an urban area. Results of these studies are of use to green roof designers, engineers, and installation contractors and may potentially be used in any carbon cap and trade program that may be adopted in the future. Findings from our green roof research program have already been utilized in the design and construction of the worlds largest green roof (10.4 acres) on the Ford Motor Company assembly plant in Dearborn, Michigan. The potential of green roofs for economic and environmental impact is outstanding considering that the market consists of all existing and future buildings.

Publications

• Getter, K.L., Rowe, D.B., Robertson, G.P., Cregg, B.M., Andresen, J.A. 2009. Carbon sequestration potential of extensive green roofs. Environmental Science and Technology 43:7564-7570.
• Getter, K.L., Rowe, D.B, Cregg, B.M. 2009. Solar radiation intensity influences extensive green roof plant communities. Urban Forestry and Urban Greening 8:269-281.
• Getter, K.L., Rowe, D.B. 2009. Substrate depth influences sedum plant community on a green roof. HortScience 44:401-407.
• Getter, K.L., Rowe, D.B. 2009. Carbon sequestration potential of extensive green roofs. Proc. of 7th North American Green Roof Conference: Greening Rooftops for Sustainable Communities, Atlanta, GA. 3-5 June 2009. The Cardinal Group, Toronto.

Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: Green roofs, a roofing technology that entails growing plants on rooftops, provide many benefits such as improved stormwater management, energy conservation, mitigation of the urban heat island effect, increased longevity of roofing membranes, reduction in noise and air pollution, and improved aesthetics. Species selection, season of planting, and initial establishment are critical for long term survival and health of green roofs. Plants that can withstand harsh environmental conditions and provide rapid coverage on extensive green roofs can reduce erosion, limit weed invasion, and provide a more aesthetically pleasing roof to satisfy customers. Plugs of nine species of Sedum were planted in East Lansing, MI in autumn (September 20, 2004) or spring (June 8, 2005) and then evaluated for survival on June 1, 2005 and June 1, 2006 respectively. Overall, spring planting exhibited superior survival rates (81%) compared to autumn (23%) across substrate depths. Sedum cauticola Lidakense, S. floriferum, and S. sexangulare were not affected by season of planting. Sedum cauticola barely survived at any substrate depth or planting season, whereas the latter two exhibited nearly 100% survival regardless of planting season. All other species had superior survival percentages when planted during spring. A second study evaluated the effect of green roof substrate depth on initial establishment of 12 Sedum species in a Midwestern U.S. climate. Plugs of 12 Sedum species were planted on 8 June 2005 and evaluated bi-weekly until first frost for absolute cover (AC) using a stainless steel point-frame transect. Most species exhibited greater growth and coverage at a depth of 7.0 cm and 10.0 cm relative to 4.0 cm. AC was highest for S. sarmentosum at all depths, but this species may be too aggressive. Other suitable species include S. floriferum, S. stefco, and S. spurium `John Creech'. In general, species that are less suitable are S. `Angelina', S. cauticola `Lidakense', S. ewersii, S. ochroleucum, and S. reflexum `Blue Spruce'. For the species tested, a minimum of 7.0 cm is highly recommended. With shallower substrates, S. sarmentosum and S. stefco will provide the fastest coverage. Findings from our research were published in peer-reviewed scientific journals, an extension bulletin, and in proceedings of conferences. Oral presentations were made at Texas A&M and Saginaw Valley State University; at conferences of Green Roofs for Healthy Cities, GWA, IGIA, MDEQ, MDLEQ, MHA, MWEA, and PGMS, as well as numerous other presentations including and interview on NPR and guest lectures to classes in Landscape Architecture, Environmental Studies, Horticulture, and Urban Planning. In addition, I have developed and maintained a website covering my research program: www.hrt.msu.edu/greenroof that had over 25,000 hits during 2008. PARTICIPANTS: Jeff Andresen has been involved primarily as a member of graduate student committees, with experimental design, and for his expertise with monitoring equipment. John Lloyd is a heat flux expert in Mechanical Engineering working on the energy data. Kristin Getter and Leigh Whittinghill are current graduate students. The following companies or professional organizations have contributed direct support or in-kind support: Behrens Systementwicklung, Grosse Ippener, Germany; Ford Motor Company, Dearborn, MI; Green Roof Plants, Street, MD; Hortech, Inc., Spring Lake, MI; LiveRoof, LLC, Spring Lake, MI; and XeroFlor America, LLC, Durham, NC. Two current PhD graduate students are working on the project. Training of students is occurring in my classes HRT 492 Undergraduate Research and HRT 413 Sustainable Landscape Practices. As a member of ASTM International subcommittee on green roof systems, much of our research results are being incorporated into ASTM standards. Also as a member of Green Roofs for Healthy Cities Green Roof Professional Education Committee, information is being incorporated into a certification course we are developing on plant and growing media. TARGET AUDIENCES: Professionals involved with the green roof industry and government officials that develop policy for environmental stewardship. This includes green roof designers, landscape architects, architects, roofing contractors, green roof manufacturers and suppliers, fellow researchers, students, and the general public. PROJECT MODIFICATIONS: Future emphasis will shift to carbon sequestration.

Impacts
Most of the species examined in these studies have not been previously reported for use on green roofs, therefore, this study offers new plant recommendations. Results of these studies are of use to green roof designers, engineers, and installation contractors, as well as to nursery's that provide the plant material. Findings from our green roof research program have already been utilized in the design and construction of the worlds largest green roof (10.4 acres) on the Ford Motor Company assembly plant in Dearborn, Michigan. The potential of green roofs for economic and environmental impact is outstanding considering that the market consists of all existing and future buildings.

Publications

• Getter, K.L., Rowe, D.B. 2008. Media depth influences Sedum green roof establishment. Urban Ecosystems 11:361-372.
• Getter, K.L., Rowe, D.B. 2008. Selecting plants for extensive green roofs in the U.S. Extension Bulletin E-3047, Michigan State University.
• Getter, K.L., Rowe, D.B. 2008. Carbon sequestration potential of extensive green roofs. Proc. of World Green Roof Conference, London, U.K. 17-18 Sept, 2008.
• Getter, K.L., Rowe, D.B. 2008. Effect of solar radiation levels on native and non-native species. Proc. of 6th North American Green Roof Conference: Greening Rooftops for Sustainable Communities, Baltimore, MD. 30 April -2 May, 2008. The Cardinal Group, Toronto.
• Rowe, D.B., Getter, K.L., Andresen, J.A., Lloyd, J.R. 2008. Green roof research at Michigan State University. Proc. of 6th North American Green Roof Conference: Greening Rooftops for Sustainable Communities, Baltimore, MD. 30 April -2 May, 2008. The Cardinal Group, Toronto.

Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: Plants on rooftops are more susceptible to extremes in temperature and drought due to their shallow substrate and elevation above ground. For green roofs to be successful in the US, it is critical to increase the number of proven plant resources for long term survival on rooftops and to quantify the ability of green roofs to reduce stormwater runoff. Successful plant taxa for extensive green roofs must establish themselves quickly, provide high groundcover density, and tolerate extreme environmental conditions. Furthermore, dead load weight restrictions on many buildings limit the substrate depth that can be applied. We evaluated the effect of substrate depth on initial establishment and survival of 25 succulent plant taxa. Survival, initial growth, and rate of coverage were compared for plants grown in three substrate depths (2.5, 5.0, and 7.5 cm) on 24 roof platforms. Plant coverage was determined from image analysis of weekly digital photographs. Deeper substrates promoted greater survival and growth, however, in the shallowest depth of 2.5 cm, several species continued to persist. Of the 25 species initially planted, only 47% survived in the deepest substrate of 7.5 cm. Recommended species at the depths tested for climates similar to southern Michigan include Phedimus spurious, Sedum acre, S. album, S. middendorffianum, S. reflexum, S. sediforme, and S. spurium. Subsidiary species that are present at specific substrate depths, but may not exhibit an ability to cover large areas include S. dasyphyllum, S. diffusum, S. hispanicum, and S. kamtschaticum. The primary deterrent for these subsidiary species was little to no survival at 2.5 cm. Deeper substrates promoted greater survival and growth for nearly all species tested. Regarding stormwater management, green roof technologies, are increasingly being used to alleviate runoff problems. To quantify the effect that roof slope has on green roof stormwater retention, runoff was analyzed from twelve green roof platforms constructed at four slopes (2%, 7%, 15%, and 25%). Data demonstrated an average retention value of 80.8%. Mean retention was least at the 25% slope (76%) and greatest at the 2% slope (85%). In addition, runoff that did occur was delayed and distributed over a long period of time for all slopes. Curve numbers, a common method used by engineers to estimate stormwater runoff for an area, ranged from 84 to 90, and are all lower than a conventional roof curve number of 98, indicating that these greened slopes reduced runoff compared to traditional roofs. Findings from our research were published as four papers in peer-reviewed scientific journals and four others in proceedings of conferences or in trade journals. Oral presentations were made at conferences of Green Roofs for Healthy Cities, ASHS, ASLA, MSFA, MNLA, and Master Gardeners, as well as numerous other presentations including six guest lectures to classes in Landscape Architecture, Environmental Studies, Journalism, and Horticulture. In addition, I have developed and maintained a website covering my research program: www.hrt.msu.edu/greenroof that had over 20,000 hits during 2007. PARTICIPANTS: Clayton Rugh was an initial member of the team that left MSU two years ago and now owns his own green roof company, XeroFlor America. Jeff Andresen has been involved primarily as members of graduate student committees, with experimental design, and for his expertise with monitoring equipment. Diane Ebert-May was a member of a graduate committee and provided expertise in the use of point frames to record plant community development. Angela Durhman was a former graduate student and Kristin Getter is a current graduate student. The following companies or professional organizations have contributed direct support or in-kind support: Behrens Systementwicklung, Grosse Ippener, Germany; Carolina Stalite, Salisbury, NC; ChristenDETROIT Roofing Contractors, Detroit, MI; Ford Motor Company, Dearborn, MI; Green Roof Plants, Street, MD; Hortech, Inc., Spring Lake, MI; International Sedum Society, Northumberland, United Kingdom; McDonough Braungart Design Chemistry, Charlottesville, VA; Meridian Township Planning Commission, Okemos, MI; Michigan Department of Agriculture; MSU Office of VP Operations and Finance; MSU Project GREEEN; Perennial Plant Association; Renewed Earth, Kalamazoo, MI; Wildtype Nursery, Mason, MI; and XeroFlor America, LLC, Durham, NC. One current PhD graduate student is working on the project. Training of students is occurring in my classes HRT 492 Undergraduate Research and HRT 413 Sustainable Landscape Practices. As a member of ASTM International subcommittee on green roof systems, much of our research results are being incorporated into ASTM standards. Also as a member of Green Roofs for Healthy Cities Green Roof Professional Education Committee, information is also being incorporated into a certification course we are developing on plant and growing media. TARGET AUDIENCES: Professionals involves with the green roof industry and government officials that develop policy for environmental stewardship. This includes green roof designers, landscape architects, architects, roofing contractors, green roof manufacturers and suppliers, fellow researchers, students, and the general public. PROJECT MODIFICATIONS: Future emphasis will shift from stormwater to carbon sequestration.

Impacts
Most of the species examined in these studies have not been previously reported for use on green roofs, therefore, this study offers new plant recommendations. Also, based on the results of the stormwater study, if all 1.1 sq km (12 million sq ft) of flat roof surface on the campus of Michigan State University were greened similar to the roof platforms used in this study, these roofs would have retained 377,041 cubic meters (99,603,827 gallons) of stormwater during 2005. This could have a major economic impact on stormwater infrastructure. Results of these studies are of use to green roof designers, engineers, and installation contractors, as well as to nursery's that provide the plant material. Findings from our green roof research program have already been utilized in the design and construction of the worlds largest green roof (10.4 acres) on the Ford Motor Company assembly plant in Dearborn, Michigan. The potential of green roofs for economic and environmental impact is outstanding considering that the market consists of all existing and future buildings.

Publications

• Durhman, A.K., Rowe, D.B., Rugh, C.L. 2007. Effect of substrate depth on initial growth, coverage, and survival of 25 succulent green roof plant taxa. HortScience 42(3):588-595.
• Getter, K.L., Rowe, D.B., Andresen, J.A. 2007. Quantifying the effect of slope on extensive green roof stormwater retention. Ecological Engineering 31:225-231.
• Getter, K.L., Rowe, D.B. 2007. Effect of substrate depth and planting season on Sedum plug establishment for green roofs. J. Environ. Hort 25(2):95-99.
• Oberndorfer, E., Lundholm, J., Bass, B., Connelly, M., Coffman, R., Doshi, H., Dunnett, N., Gaffin, S., Kohler, M., Lui, K., Rowe, B. 2007. Green roofs as urban ecosystems: ecological structures, functions, and services. BioScience 57(10):823-833.
• Getter, K.L., Rowe, D.B. 2007. Effect of substrate depth and planting season on Sedum plug establishment for extensive green roofs. Proceedings of 5th North American Green Roof Conference: Greening Rooftops for Sustainable Communities, Minneapolis, MN. 29 April -2 May, 2007. The Cardinal Group, Toronto.
• Rowe, D.B. 2007. The role of green roofs in sustainable landscapes. HortScience 42(4):824.
• Rowe, D.B., Getter, K.L., Andresen, J.A., Lloyd, J.R. 2007. The green roof research program at Michigan State University. HortScience 42(4):1003.
• Rowe, D.B. 2007. GRHC Research committee update. The Green Roof Infrastructure Monitor 9(1):31.

Progress 01/01/06 to 12/31/06

Outputs
Green roof technology in the United States is in the early development stage. There is a need to define growing substrates, evaluate potential plant species, and characterize stress tolerances. High levels of substrate organic matter is not recommended because it will decompose resulting in substrate shrinkage and can leach nutrients in the runoff. Also, there much interest in utilizing native species and recreating natural prairies on rooftops. Since most of these native species are not succulents, it is not known if they can survive on shallow extensive green roofs without irrigation. Five planting substrate compositions containing 60, 70, 80, 90, and 100% of heat-expanded slate were used to evaluate two Sedum spp. and six non-succulent natives over a period of three years. The study was conducted on roof platforms containing 10 cm of substrate. Higher levels of heat-expanded slate in the substrate generally resulted in slightly less growth and lower visual ratings across all species. After three years, all plants of Aster laevis, Monarda punctata, Rudbeckia hirta, and Solidago speciosa were dead. To a lesser degree, half of the Coreopsis lanceolata survived in 60 and 70% heat-expanded slate, but only a third of the plants survived in 80, 90, or 100%. Regardless of substrate composition, both Sedum middendorffianum and S. spurium achieved 100% coverage in one year and maintained this coverage into the third season. Results suggest that a moderately high level of heat-expanded slate (approximately 80%) can be utilized for green roof applications when growing succulents such as sedum. However, the non-succulents required deeper substrates, additional organic matter, or supplemental irrigation. By reducing the amount of organic matter in the substrate, potential contaminated discharge of N, P, and other nutrients from green roofs is likely to be reduced considerably. A second greenhouse experiment was conducted to determine the effect of watering regimens on plant stress as measured by chlorophyll fluorescence (Fv/Fm), biomass accumulation, substrate moisture, and evapotransipiration on succulent plants of Sedum acre, S. reflexum, S. kamtschaticum, and non-CAM plants of Schizachyrium scoparium, and Coreopsis lanceolata. Plants were grown at a substrate depth of 7.5 cm. Results indicate even after the four month period, Sedum spp. survived and maintained active photosynthetic metabolism, relative to Schizachyrium and Coreopsis. Furthermore, when Sedum was watered after 28 days of drought, Fv/Fm values recovered to values characteristic of the 2 days between watering (DBW) treatment. In contrast, the non-CAM plants required watering frequency every other day in order to survive and maintain active growth and development. Regardless of species, the greatest increase in total biomass accumulation and fastest growth occurred under the 2 DBW regimens. The ability of Sedum to withstand extended drought conditions makes it ideal for shallow green roof systems. In addition, a study looking at the effect of roof slope on stormwater retention is currently being conducted.

Impacts
Use of green roof technology is becoming increasingly widespread throughout the world because of its environmental, economic, and aesthetic benefits. The ability of a green roof to retain stormwater, provide insulation for buildings, mitigate the Urban Heat Island Effect, and provide an aesthetically pleasing environment in which to work and live are important characteristics of a properly installed green roof system. However, scientific research quantifying these characteristics is limited, particularly in the United States. If green roof installations are to be successful in Michigan and the rest of the U.S., then these benefits must be quantified and a better understanding of what specific plant taxa will survive and thrive under harsh rooftop conditions in this geographic area are required. Several studies are being conducted to help predict essential design requirements for green roof construction and implementation. Findings from our green roof research program have already been utilized in the design and construction of the worlds largest green roof (10.4 acres) on the new Ford Motor Company assembly plant in Dearborn, Michigan. The potential of green roofs for economic and environmental impact is outstanding considering that the market consists of all existing and future buildings.

Publications

• Durhman, A.K., Rowe, D.B., Rugh, C.L. 2006. Effect of watering regimen on chlorophyll fluorescence and growth of selected green roof plant taxa. HortScience 41:1623-1628.
• Getter, K.L., Rowe, D.B. 2006. The role of green roofs in sustainable development. Hort Science 41:1276-1285.
• Rowe, D.B., Monterusso, M.A., Rugh, C.L. 2006. Assessment of heat-expanded slate and fertility requirements in green roof substrates. HortTechnology 16:471-477.
• Rowe, D.B., Rugh,C.L., Durhman, A.K. 2006. Assessment of substrate depth and composition on green roof plant performance. Proceedings of 4th North American Green Roof Conference: Greening Rooftops for Sustainable Communities, Boston, MA. 10-12 May, 2006. The Cardinal Group, Toronto.
• Getter, K.L. 2006. Evaluation of plant species and slope runoff on extensive green roofs. MS Thesis, Michigan State University, East Lansing.

Progress 01/01/05 to 12/31/05

Outputs
Several green roof experiments were conducted in controlled environment greenhouse studies, on simulated roof platforms, and on the roof of the Plant and Soil Sciences Building. Research is being conducted in three areas: plant evaluations of potential green roof taxa, stormwater retention, and energy conservation. The main research thrust is plant evaluations where we are looking at plant establishment, stress tolerance, competition, and diversity. A greenhouse study was conducted to determine how water availability influences growth and survival of a mixture of Sedum spp. on a green roof drainage system. Results indicate that substrate volumetric moisture content can be reduced to zero within one day after watering depending on substrate depth and composition. Deeper substrates provided additional growth with sufficient water, but also required additional irrigation because of the higher evapotranspiration rates resulting from the greater biomass. Over the 88 day study, water was required at least once every 14 days to support growth in green roof substrates with a 2 cm media depth. However, substrates with a 6 cm media depth could do so with a watering only once every 28 days. Although vegetation was still viable after 88 days of drought, water should be applied at least once every 28 days for typical green roof substrates and more frequently for shallower substrates to sustain growth. The ability of Sedum to withstand extended drought conditions makes it ideal for shallow green roof systems. Regarding stormwater retention, two studies were completed using several roof platforms to quantify the effects of various treatments on stormwater retention. The first study utilized three different roof surface treatments to quantify differences in stormwater retention of a standard commercial roof with gravel ballast, an extensive green roof system without vegetation, and a typical extensive green roof with vegetation. Overall, mean percent rainfall retention ranged from 48.7% (gravel) to 82.8% (vegetated). The second study tested the influence of roof slope (2% and 6.5%) and green roof media depth (2.5 cm, 4.0 cm, and 6.0 cm) on stormwater retention. For all combined rain events, platforms at 2% slope with a 4 cm media depth had the greatest mean retention, 87%, although the difference from the other treatments was minimal. The combination of reduced slope and deeper media clearly reduced the total quantity of runoff. For both studies, vegetated green roof systems not only reduced the amount of stormwater runoff, they also extended its duration over a period of time beyond the actual rain event. In addition, an extensive green roof was installed on the Plant and Soil Science Building. This roof has been instrumented with a weather station, thermocouples, soil moisture probes, and heat flux sensors. Data will be used to develop a model for energy conservation.

Impacts
Use of green roof technology is becoming increasingly widespread throughout the world because of its environmental, economic, and aesthetic benefits. The ability of a green roof to retain stormwater, provide insulation for buildings, mitigate the Urban Heat Island Effect, and provide an aesthetically pleasing environment in which to work and live are important characteristics of a properly installed green roof system. However, scientific research quantifying these characteristics is limited, particularly in the United States. If green roof installations are to be successful in Michigan and the rest of the U.S., then these benefits must be quantified and a better understanding of what specific plant taxa will survive and thrive under harsh rooftop conditions in this geographic area are required. Several studies are being conducted to help predict essential design requirements for green roof construction and implementation. Findings from our green roof research program have already been utilized in the design and construction of the worlds largest green roof (10.4 acres) on the new Ford Motor Company assembly plant in Dearborn, Michigan. The potential of green roofs for economic and environmental impact is outstanding considering that the market consists of all existing and future buildings.

Publications

• VanWoert, N.D, Rowe, D.B., Andresen, J.A., Rugh, C.L., Fernandez, R.T. and Xiao, L. 2005. Green roof stormwater retention: Effects of roof surface, slope, and media depth. J. Environ. Quality 34:1036-1044.
• VanWoert, N.D, Rowe, D.B., Andresen, J.A., Rugh, C.L. and Xiao, L. 2005. Watering regime and green roof substrate design affect Sedum plant growth. HortScience 40:659-664.
• Rowe, D.B., Monterusso, M.A. and Rugh, C.L. 2005. Evaluation of Sedum spp. and Michigan native taxa for green roof applications. Proceedings of 3rd North American Green Roof Conference: Greening Rooftops for Sustainable Communities. 3:469-481.
• Monterusso, M.A., Rowe, D.B. and Rugh, C.L. 2005. Establishment and persistence of Sedum spp. and native taxa for green roof applications. HortScience 40:391-396.
• Durhman, A.K. 2005. Evaluation of Crassulacean species for extensive green roof applications. MS Thesis, Michigan State University, East Lansing.

Progress 01/01/04 to 12/31/04

Outputs
Several green roof experiments are being conducted in controlled environment greenhouse studies, on simulated roof platforms, and on the roof of the Plant and Soil Sciences Building. Research is being conducted in three areas: plant evaluations of potential green roof taxa, stormwater retention, and energy conservation. The main research thrust is plant evaluations where we are looking at plant establishment, stress tolerance, competition, and diversity. A study conducted on roof platforms was recently completed where eighteen Michigan native plants planted were evaluated over three years for growth, survival during both establishment and overwintering, and visual appearance. All Sedum spp. tested were found to be suitable for use on Midwestern green roofs. Of the eighteen native plant taxa tested, Allium cernuum, Coreopsis lanceolata, Opuntia humifosa, and Tradescantia ohiensis were found to be suitable for use on unirrigated extensive green roofs in Michigan. If irrigation is available, then other native species are potential selections. In another experiment, plant establishment and survival studies are being conducted on forty-eight (2.44 m by 2.44 m) raised roof platforms. Twenty-five succulent plant species are being evaluated at three substrate depths (2.5, 5.0, and 7.5 cm) for such characteristics as propagation success, rate of establishment, growth and survival, groundcover density and ability to exclude invasive weeds, competition among species, persistence over several years, cold tolerance, and drought resistance. Image analysis software is being utilized to analyze digital photographs taken over time in order to determine the percentage of plant canopy that can be attributed to each individual species. After initial growth rates are established and plants begin to fill in the platforms, a point-frame will be used to measure leaf area index in order to evaluate plant competition. Regarding stormwater retention, runoff was analyzed from four commercially available green roof systems containing three distinct vegetation types. Quantity of rainfall retained ranged from 38.6% for XeroFlor to 58.1% for Siplast. Quantitatively, Xeroflor resulted in the greatest volume of runoff, but these volumes were only significant for the sections of Sedum plugs and seed during the fourth rainfall event. Differences in water retention can likely be attributed to substrate depth, rather than drainage system or vegetation type. Results demonstrate two important concepts that affect the amount of stormwater a green roof can retain: substrate thickness and substrate moisture content immediately prior to a rainfall event. In addition, an extensive green roof was installed this summer on the Plant and Soil Science Building. This roof has been instrumented with a weather station, thermocouples, soil moisture probes, and heat flux sensors. Data will be used to develop a model for energy conservation.

Impacts
Use of green roof technology is becoming increasingly widespread throughout the world because of its environmental, economic, and aesthetic benefits. The ability of a green roof to retain stormwater, provide insulation for buildings, mitigate the Urban Heat Island Effect, and provide an aesthetically pleasing environment in which to work and live are important characteristics of a properly installed green roof system. However, scientific research quantifying these characteristics is limited, particularly in the United States. If green roof installations are to be successful in Michigan and the rest of the U.S., then these benefits must be quantified and a better understanding of what specific plant taxa will survive and thrive under harsh rooftop conditions in this geographic area are required. Several studies are being conducted to help predict essential design requirements for green roof construction and implementation. Findings from our green roof research program have already been utilized in the design and construction of the worlds largest green roof (10.4 acres) on the new Ford Motor Company assembly plant in Dearborn, Michigan. The potential of green roofs for economic and environmental impact is outstanding considering that the market consists of all existing and future buildings.

Publications

• Cregg, B.M., Duck, M.W., Rios, C.M., Rowe, D.B., Koelling, M.R. 2004. Chlorophyll fluorescence and needle chlorophyll concentration of true fir (Abies spp.) seedlings in response to pH. HortScience 39:1121-1125.
• Durhman, A., VanWoert, N.D., Rowe, D.B., Rugh, C.L., Ebert-May, D. 2004. Evaluation of Crassulacean species on extensive green roofs. Proceedings of Second North American Green Roof Conference: Greening Rooftops for Sustainable Communities, 504-517 pp.
• Monterusso, M.A., Rowe, D.B., Rugh, C.L., Russell, D.K. 2004. Runoff water quantity and quality from green roof systems. Acta Hort 639:369-376.
• Rowe, D.B., Fernandez, R.T., Cregg, B.M. 2004. Effect of wool pellet mulch on propagation, crop growth, and weed control in liners. Propagation of Ornamental Plants 4(2):29-36.
• Rowe, D.B., Rugh, C.L., Monterusso, M.A. 2004. Evaluation of potential plant species for green roofs. Michigan State University Nursery and Landscape Research Projects and Educational Programs Report. 52-53 pp.

Progress 01/01/03 to 12/31/03

Outputs
Several experiments were conducted over the past five years involving propagation and plant production. First, chlorophyll fluorescence (Fv/Fm) was utilized to assess the effect of cuttings of four cultivars of Taxus exposed to various cold storage conditions on adventitious rooting. Cultivars differed in Fv/Fm initially, as well as over time, but Fv/Fm could detect substandard storage conditions only at temperature and desiccation extremes. Second, we studied the use of wool pellet mulch for potential weed control capabilities during propagation of rooted cuttings. Wool pellets suppressed weeds and enhanced shoot and dry weight accumulation in some cases. However, the mulch resulted in higher plant mortality, probably because of higher substrate moisture. If intermittent mist practices were altered to account for the reduced evaporation from the substrate, it is feasible that this problem could be solved. Third, several green roof experiments are being conducted studying substrate composition, plant propagation and establishment, plant species, nutritional requirements, green roof drainage systems, and water quality and quantity of precipitation runoff. Combinations of 18 herbaceous species native to Michigan and nine species of Sedum were evaluated for rate of establishment, capability to exclude invasive weeds, temperature tolerances, and drought tolerance. These experiments were conducted on 27 roof platforms. Without supplemental irrigation, all herbaceous species except Allium cernuum and Coreopsis lanceolata died. However, Sedum thrived during these drought conditions. Drought tolerant succulents such as Sedum are ideal for low maintenance shallow extensive green roofs. Also, greenhouse studies are being conducted utilizing chlorophyll fluoresence to quantify drought and other environmental stresses of 39 species and cultivars of Sedum.

Impacts
Procedures that help growers produce marketable plants in a shorter period of time and reduce labor costs can offer numerous economic benefits. Mulching with wool pellets helped to control weeds that reduce crop growth through competition for light, water, and nutrients. They may also reduce the need for herbicide applications, which in turn may limit potential crop damage, lessen exposure of chemicals to nursery workers, and result in less contamination of our environment. In addition, chlorophyll fluorescence is a rapid, reliable method of measuring plant stress and can be used to determine the effects of storage conditions on adventitious rooting as well as helping to identify stress tolerant species that may be suitable for green roof applications. The potential of green roofs for economic and environmental impact is outstanding considering that the market is all existing and future buildings.

Publications

• Rowe, D.B. 2003. Green roofs: A new market. Proc. Southern Nursery Assoc. Res. Conf. 48:367-369.
• Rowe, D.B., Rugh, C.L. 2003. The green roof research program at Michigan State University. Proc. Intl. Plant Prop. Soc. 53:xx-xx.
• Rowe, D.B., Rugh, C.L., VanWoert, N., Monterusso, M.A., Russell, D.K. 2003. Green roof slope, substrate depth, and vegetation influence runoff. Proceedings of First North American Green Roof Conference: Greening Rooftops for Sustainable Communities, 354-362 pp.
• VanWoert, N., Durhman, A., Rowe, D.B., Rugh, C.L., Monterusso, M.A., Russell, D.K., Fernandez, R.T, Andresen, J. 2003. The green roof research program at Michigan State University. HortScience 38:705.
• VanWoert, N., Rowe, D.B, Rugh, C.L. 2003. Green roof slope, substrate depth, and vegetation influence runoff. HortScience 38:705.

Progress 01/01/02 to 12/31/02

Outputs
Several experiments were conducted in regards to propagation and plant production. First, chlorophyll fluorescence (Fv/Fm) was utilized to assess the effect of cuttings of four cultivars of Taxus exposed to various cold storage conditions on adventitious rooting. Cultivars differed in Fv/Fm initially, as well as over time, but Fv/Fm could detect substandard storage conditions only at temperature and desiccation extremes. Second, we studied the use of wool pellet mulch for potential weed control capabilities during propagation of rooted cuttings. Wool pellets suppressed weeds and enhanced shoot and dry weight accumulation in some cases. However, the mulch resulted in higher plant mortality, probably because of higher substrate moisture. If intermittent mist practices were altered to account for the reduced evaporation from the substrate, it is feasible that this problem could be solved. Third, several green roof experiments are being conducted studying substrate composition, plant propagation and establishment, plant species, nutritional requirements, green roof drainage systems, and water quality and quantity of precipitation runoff. Combinations of 18 herbaceous species native to Michigan and nine species of Sedum are being evaluated for rate of establishment, capability to exclude invasive weeds, temperature tolerances, and drought tolerance. These experiments are currently being conducted on 27 simulated roof platforms equipped with Campbell Scientific automated equipment including a weather station, thermocouples installed at various substrate depths, and electronic tipping buckets installed to measure rate and volume of precipitation runoff from individual platforms. Also, greenhouse studies are being conducted utilizing chlorophyll fluoresence to quantify drought and other environmental stresses of 39 less-common species and cultivars of Sedum.

Impacts
Procedures that help growers produce marketable plants in a shorter period of time and reduce labor costs can offer numerous economic benefits. Mulching with wool pellets helped to control weeds that reduce crop growth through competition for light, water, and nutrients.They may also reduce the need for herbicide applications, which in turn may limit potential crop damage, lessen exposure of chemicals to nursery workers, and result in less contamination of our environment. In addition, chlorophyll fluorescence is a rapid, reliable method of measuring plant stress and can be used to determine the effects of storage conditions on adventitious rooting as well as helping to identify stress tolerant species that may be suitable for green roof applications. The potential of green roofs for economic and environmental impact is outstanding considering that the market is all existing and future buildings.

Publications

• Rowe, D.B. and Fernandez, R.T. 2002. Weed control during liner production of Hydrangea serrata utilizing self-felting wool pellets. Proc. Southern Nursery Assoc. Res. Conf. 47:393-396.
• Monterusso, M.A., Rowe, D.B., and Rugh, C.L. 2002. Green roof drainage system and plant species influence water quality and quantity of runoff. ISHS International Horticultural Congress 26:209 (Abstr.)
• Cregg, B.M., Koelling, M., Rowe, D.B., Duck, M.W., and Rios, C.M. 2002. Screening exotic firs for pH tolerance. ISHS International Horticultural Congress 26:461 (Abstr.)
• Monterusso, M.A. 2002. Species evaluation and runoff analysis from green roof systems. MS Thesis, Michigan State University, East Lansing.
• Bruce, S.E., Rowe, D.B., and Flore, J.A. 2002. Chlorophyll fluorescence to measure effects of cold storage on rooting of stem cuttings of Taxus. Propagation of Ornamental Plants 2(1):44-50.
• Rowe, D.B., and Cregg, B.M. 2002. Effect of incorporating controlled-release fertilizer on growth during adventitious rooting of Artemisia, Gaura, and Nepeta. J. Environ. Hort. 20(1):1-6.
• Rowe, D.B., Rugh, C.L., and Russell, D.K. 2002. Green roof installation at Ford Motor Company. Proc. Intl. Plant Prop. Soc. 52:xx-xx.

Progress 01/01/01 to 12/31/01

Outputs
Several experiments were conducted in regards to propagation and plant production. First, chlorophyll fluorescence (Fv/Fm) was tested to see if it would provide a rapid and reliable indicator of plant nutrient status. Measurements of Fv/Fm, growth, biomass allocation to roots and shoots, and foliar nutrient content were taken on five common landscape conifers grown under varying nutrition. Results suggest Fv/Fm is useful in determining optimal nutrient application rates. However, differentiating between sub-optimal and supra-optimal Fv/Fm readings will require additional information, such as fertilization history or foliar symptoms. Second, Fv/Fm is being examined as a potential tool for stock plant selection, as a predictor of adventitious rooting, and we monitored stress over the course of propagation of Gisela cherry rootstocks. Third, we studied the use of wool pellets as mulch for potential weed control capabilities. Tests were conducted on herbaceous and woody species in both the rooting and growing-on phases of production. Wool pellets were compared to the herbicides Gallery 75 DF (isoxaben) and Factor 65 WG (prodiamine), to pellets treated with copper hydroxide, and to a control consisting of conventional practices. Wool pellets suppressed weeds and enhanced shoot and dry weight accumulation in some cases. However, their use resulted in higher plant mortality, probably because of higher substrate moisture. If irrigation practices were altered to account for the reduced evaporation from the substrate, it is feasible that this problem could be solved. Fourth, we are beginning some propagation studies to determine plant species that will survive and thrive in a rooftop environment.

Impacts
Procedures that help growers produce marketable plants in a shorter period of time, and reduce labor costs, can offer numerous economic benefits. Chlorophyll fluorescence is a rapid, reliable method of measuring plant stress and can be used to determine nutrient deficiencies that can retard growth. In addition, weeds reduce crop growth through competition for light, water, and nutrients. Mulching with wool pellets helped to control weeds in liners, and may reduce the need for herbicide applications, which in turn may limit potential crop damage, lessen exposure of chemicals to nursery workers, and result in less contamination of our environment.

Publications

• Bruce,S.E., Rowe,D.B. and Flore,J.A. 2001 Chlorophyll fluorescence in vegetative propagation of Taxus. HortScience 36(5):971-975.
• Rowe,D.B. and Fernandez,R.T. 2001. Weed control in perennial production utilizing self-felting wool pellets. Proc. Southern Nursery Assoc. Res. Conf. 46:425-428.
• Rowe,D.B. and Fernandez,R.T. 2001. Self-felting wool pellets as a means of weed control during propagation and liner production. Proc. Intl. Plant Prop. Soc. 51:xx-xx.
• Rowe,D.B. and Fernandez,R.T. 2001. Self-felting wool pellets as a means of weed control for propagation and liner production. HortScience 36(3):585(Abstr.).
• Cregg,B.M.,Rowe,D.B.,Fernandez,R.T.,Duck,M.W. and Rios,C.M. 2001. Evaluating conifer nutrient status via chlorophyll fluorescence. HortScience 36(3):542(Abstr.).

Progress 01/01/00 to 12/31/00

Outputs
Several experiments were conducted in regards to propagation of stem cuttings. First, chlorophyll flurorescence (Fv/Fm) is being examined as a potential tool for stock plant selection, as a predictor of adventitious rooting, and we monitored stress over the course of propagation of Gisela cherry rootstocks. Second, we studied the effect of incorporating slow release fertilizer into the rooting substrate on adventitious rooting and growth of Artemisia ludoviciana 'Valerie Finnis', Gaura lindheimeri 'Whirling Butterflies', and Nepeta x faassenii 'Six Hills Giant'. Treatments consisted of Nutricote 13-13-13 Type 180 and Nutricote 18-6-8 Type 180 incorporated into the rooting media each at 3, 6, 9, and 12 g/L, and a control with no Nutricote. Fertilizer treatments did not influence rooting percentage and no significant differences were found between the two formulations of fertilizer for top growth, root growth, rooting percentage, or root number. However, regardless of formulation or rate, the eight fertilizer treatments resulted in greater top and root dry weights when compared to the control. Top and root dry weight increased linearly within both fertilizer formulations. Third, three experiments examined timing of Wulpak wool pellet application and use of Wulpak and herbicides in liners for five herbaceous perennials and two woody species: Brunnera macrophylla, Osmunda regalis, Lamium maculatum 'White Nancy', Buddleia davidii, Papavar carneum, Hydrangea serrata 'Blue Bird' and Itea virginica 'Henry's Garnet'. Flats were inoculated with three species of weeds: hairy bittercress (Cardamine hirsuta), liverwort (Marchantia polymorpha), and yellow woodsorrel (Oxalis spp.). The propagation timing study consisted of three treatments: an application of Wulpak (155 g/sqft of surface) prior to sticking, an application during the transition from propagation to growing-on, and a control consisting of no Wulpak. The other two experiments examined effects of Wulpak and herbicides on weed control and plant growth and consisted of five treatments applied to rooted liners: wool pellets, wool pellets treated with SpinOut, the herbicides Gallery 75 DF (isoxaben) and Factor 65 WG (prodiamine), and a control. Applications of Wulpak suppressed weeds, but its use is questionable during propagation of cuttings. Once cuttings were rooted, the application of Wulpak + Spinout and Wulpak alone enhanced shoot and root dry weight accumulation in all species. The negative effect of Wulpak was higher plant mortality. Lower survival and limited growth during propagation for cuttings stuck in flats already containing a Wulpak mulch layer was probably caused by high substrate moisture levels.

Impacts
To produce marketable plants in less time, slow-release nutrients can be incorporated into the propagation substrate, and to reduce labor costs, many plants are propagated, grown-on as liners, and shipped in the same container. Unfortunately, these practices also provide optimal conditions for weeds. Utilizing wool pellets as an alternative weed control strategy not only suppresses weeds, but may reduce the need for herbicide applications, which in turn may limit potential crop damange, lessen exposure of chemicals to nursery workers, and result in less contamination of our environment.

Publications

• Rowe, D.B. 2000. Incorporation of slow release fertilizer accelerates growth during adventitious rooting of Artemisia, Gaura, and Nepeta. HortScience 35(3):451. (Abstr.)
• Bruce, S.E., Rowe, D.B. 2000. Using chlorophyll fluorescence in storage and vegetative propagation of Taxus. HortScience 35(3):489. (Abstr.)
• Bruce, S.E., Rowe, D.B. 2000. Evaluation of stem cuttings during cold storage utilizing chlorophyll fluorescence. Proc. Southern Nurserymen's Assoc. Res. Conf., 45th Annu. Rpt. p. 300-304.
• Bruce, S.E., Rowe, D.B. 1999. Chlorophyll fluorescence as a tool in propagation. Proc. Intl. Plant Prop. Soc. 49:32-36.
• Bruce, S.E., Rowe, D.B. 1999. Chlorophyll fluorescence and rooting stem cuttings of Taxus. Proc. Southern Nurserymen's Assoc. Res. Conf., 44th Annu. Rpt. p. 346-349.

Progress 01/01/99 to 12/31/99

Outputs
Utilization of chlorophyll fluorescence in propagation by stem cuttings. Several experiments were conducted in an attempt to develop a quick, reliable method of predicting potential rooting of cuttings based on the physiological condition of the stock plant, thus potentially reducing an investment in time, labor, and resources. These studies examined chlorophyll fluorescence (Fv/Fm) as a potential tool for stock plant selection, assessment of storage conditions, and measurement of stress over the course of propagation. Ten cultivars of Taxus x media (Taxus baccata L. x T. cuspidata) were used: Brownii, Dark Green Pyramidalis, Dark Green Spreader, Densiformis, Densiformis Gem, Hicksii, L.C. Bobbink, Runyan, Tauntoni, and Wardii. Storage condition treatments consisted of desiccation (low, medium, high), duration (34, 70, 107 days), and temperature (-30, -2.5, 0, 2.5, 5, 10, and 20 C). Cultivars differed in Fv/Fm initially, as well as over time. Correlations were not found between initial stock plant Fv/Fm and rooting percentage, root number, root dry weight, or root length, indicating that Fv/Fm is not a reliable indicator of stock plant propagation potential. Short storage duration at -2.5 to 2.5 C was found to be ideal. Fv/Fm could detect substandard storage conditions only at temperature and desiccation extremes. Although chlorophyll fluorescence measurements do not appear to be a practical method of predicting adventitious rooting, there is a potential for assessing cutting or plant quality prior to shipping.

Impacts
(N/A)

Publications

• Bruce, S.E., Rowe, D.B. 1998. Use of chlorophyll fluorescence in propagation. Proc. Intl. Plant Prop. Soc. 48:475-478.