LOBLOLLY PINE-SWITCHGRASS INTERCROPPING FOR SUSTAINABLE TIMBER AND BIOFUELS PRODUCTION IN THE SOUTHEASTERN UNITED STATES

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: TERMINATED
• Funding Source: AFRI COMPETITIVE GRANT
• Reporting Frequency: Annual
• Accession No.: 0224209
• Grant No.: 2011-67009-20089
• Project No.: NCZ09474
• Proposal No.: 2010-03880
• Program Code: A6121
• Project Start Date: Mar 15, 2011
• Project End Date: Mar 14, 2018
• Grant Year: 2012

Project Director
King, J.

Recipient Organization
NORTH CAROLINA STATE UNIV
(N/A)
RALEIGH,NC 27695

Performing Department
Forestry and Environmental Resources

Non Technical Summary
Dependence on fossil fuel energy exposes the U.S. to potentially catastrophic climate change, economic instability, and risks to national security. Our goal is to develop a pine-switchgrass bioenergy production system for the southeastern U.S. based on regionally appropriate crops and indigenous biomass production practices that will benefit economic development and the environment. We hypothesize the asynchronous physiology and growth of the C3 trees and C4 grass along with the different soil horizons exploited by the respective root systems will allow for greater nutrient retention and more efficient utilization of site water. We also hypothesize that the additional soil volume exploited by switchgrass roots and associated fine root turnover, will increase soil organic C, thus increasing C sequestration. The work will be done at a 70 acre replicated field experiment installed in the Lower Coastal Plain of North Carolina being implemented by a joint venture between Weyerhaeuser and Chevron corporations, called Catchlight Energy, LLC. The experiment consists of a randomied complete block design of traditional pine silviculture and switchgrass treatments, deployed individually and together, in very large plots sufficient for ecosystem analsis. Over the course of the five-year project, we will carefully monitor ecosystem productivity and yield, soil carbon and nutrient dynamics, water utilization, and determine the greenhouse gas balance. The research will evaluate the sustainability, multi-functionality, and ecosystem services provisioning of this novel forest intercropping system. The academic-industry-government partnership will break new ground in developing a scientific understanding of forest intercropping sustainability. Further, it will strengthen institutional capacity at two of the Nation's leading forestry schools, and develop an education program designed to recruit and train the next generation of natural resources professionals in ecosystem sustainability and bioenergy sciences.

Animal Health Component

(N/A)

Research Effort Categories

Basic

50%

Applied

50%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
123	0611	1070	75%
102	0611	3100	25%

Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 123 - Management and Sustainability of Forest Resources;

Subject Of Investigation
0611 - Conifer forests of the South;

Field Of Science
1070 - Ecology; 3100 - Management;

Keywords

loblolly pine

switchgrass

bioenergy

sustainability

greenhouse gases

forest intercropping

soil carbon

water balance

resource efficiency

u.s. southeast

climate change

hydrology

biofuels

Goals / Objectives
Dependence on fossil fuel energy exposes the U.S. to potentially catastrophic climate change, economic instability, and risks to national security. Our goal is to develop a pine-switchgrass bioenergy production system for the southeastern U.S. based on regionally appropriate crops and indigenous biomass production practices that will benefit economic development and the environment. Emphasis will be placed on understanding how the novel cropping system influences the interaction of carbon, nutrient and water cycles that sustain productivity and provide important ecosystem services. Specific objectives will include: 1) Quantify rates of tree and grass productivity alone and in combination; 2) Quantify cycling rates and sustainability of soil resources (nutrients, water, carbon (C)); 3) Determine resource use efficiencies (light, nitrogen (N), water); and 4) Characterize C cycling and net C balance over the course of a full 25 year rotation. To develop this new bioenergy system and achieve the stated objectives, we have assembled a unique collaboration of scientists and natural resources professionals from academia, government, and private industry that may serve as a model of the kinds of partnerships that will be required to meet the multifaceted challenges of the new energy economy of the 21st Century.

Project Methods
Experimental design: The work will be done at a 70 acre replicated field experiment established in the Lower Coastal Plain of North Carolina, consisting of factorial arrangement of traditional loblolly pine silviculture intercropped with switchgrass. Within the plots, micrometeorology will be monitored, as well as the pools and fluxes of the carbon, water and nitrogen cycles. Biomass and NPP: Height and diameter data of all pines in the measurement plots will be collected bi-monthly. Mean canopy height of switchgrass will be made monthly. Whole trees will be harvested at the end of the growing season in year 1, 3 and 5 to develop allomatric biomass regression models. One square meter clip plots will be destructively sampled to estimate switchgrass biomass and leaf area. Soil C and N cycling: Soil C pool and flux measurements will be characterized to explain the spatial and temporal variability in C cycling dynamics imposed by each treatment combination. Soil gas flux measurements and concurrent soil sampling will be made for physical, chemical and biological soil carbon analysis. We will partition heterotrophic and autotrophic respiration using a non-destructive technique and do spatially intensive soil characterizations: soil organic matter content and quality, root biomass, microbial biomass, nutrient availability, soil chemistry, temperature, moisture, oxidation-reduction potential. Soil organic matter quality will be assessed through multiple fractionation techniques. Microbial and fungal communities will be assessed quarterly. Site water balance: Closed water balances will be developed for each treatment as: P = Es + T + D + I + S + M, where Es denotes soil evaporation, T is tree and switchgrass transpiration, D is soil drainage, I denotes rainfall interception, S is stem flow and M is the change in soil water storage. D will be calculated as the difference between P and the remaining terms of the water balance equation. Integrated water use efficiency will be calculated over the growing season as total useable plant biomass produced per total water transpired per unit land area. Site carbon balance and greenhouse gas accounting: Under the final rulemaking of the National Renewable Fuels Standard program (RFS), mandatory life-cycle GHG reduction thresholds are required. We will analyze the sustainability and feasibility of this intercropping strategy for GHG reductions and evaluate the environmental effects. All GHG emissions will be accounted for and monitored through time so that data can be provided to determine eligibility under the RFS.Data analysis and synthesis: Hypotheses will be tested using a common ANOVA model for a randomized complete block design developed specifically for this field experiment. Over the course of the project, data will be shared between groups for synthesis activities to better understand the implications of intensive pine silviculture-switchgrass intercropping on ecosystem function and biogeochemical cycling of C, nutrients, and water.

Progress 03/15/11 to 03/14/18

Outputs
Target Audience:Target audiences include undergraduate and graduate students at NCSU and Virginia Tech, Forest Service scientists and program administrators of the Southern Research Station, Weyerhaeuser technical staff and research silviculturists, state and federal program managers, and the broader scientific community. Approximately 150 undergraduate and graduate students learned about advanced bioenergy science in courses taught by project PIs King, Strahm, and Seiler on forest soils, forest ecophysiology and silviculture, and in departmental seminars. Results of this project were communicated to Forest Service research staff and interested program administrators through regular staff meetings and retreats. Weyerhaeuser technical and research staff were apprised of project progress, operational issues, and results through regular email discussions, conference calls, and field site visits. State program managers, in particular from the NC Dept of Agriculture, were apprised of project progress through regular meetings. Federal agency program managers were aprised of project results annually, and USDA NIFA annual investigator meetings and professinal society meetings. The broader scientific community was reached through presentations of results at international scientific meetings and publications. The number people reached by all of these meansis inestimbable, but must numberin the thousands over the period of performance. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Professional development opportunities were provided to undergraduate and graduate students enrolled in natural resources management curricula at NCSU and Virginia Tech universities. These opportunities primarily took the form of lecture-based courses in forest ecophysiology and productivity, forest soil science, and natural resources management. We also provided advanced scientific research training opportunities to approximately 25 undergraduate students who work on the project as research assistants/technicians. More advanced training in experimental design, measurement methodology, statistical data analysis, scientific writing and professional development were provided to four graduate students andfour postdoctoral research fellows associated with the project over the years.Information provided by our work is directly relevant to Weyerhaeuser NR Company and other bioenergy professionals to inform management and business decisions. Results of this project are also being used to parameterize ecosystem models that will be incorporated into decision support systems by the USDA Forest Service Southeast Regional Climate Hub that will translate scientific knowledge on natural/managed ecosystem responses to environmental change to end-users, including farmers, forest products industry, state agricultural/forestry agencies, etc. How have the results been disseminated to communities of interest?Results have been disseminated through peer-reviewed publications, professional meeting presentations, undergraduate and graduate classroom instruction, natural resources agency training workshops, media outlets, and K-12 educational outreach events. What do you plan to do during the next reporting period to accomplish the goals?The project has ended and this is the final report. There are no new planned activities or further reporting. However, as with most scientific projects, there is a lag between the time the work is conducted andwhen results finally appear in peer-reviewed publications. We are currently finalizing data analysis and writing of approxiimately four manuscripts that will report on total ecosystem productivity and water use, modeling and methods development, which we expect to be available within the next two years. Reprints of any new publications will be forwarded to USDA NIFA Sustainable Bioenergy program staff as they appear.

Impacts
What was accomplished under these goals? Over the six years of this project, including a no-cost extension that was requested in Year 5, wemade signficant progress onall project objectives listed above. Results were used in undergraduate and graduate classes to educate literally hundreds of students on the economics, productivity, and environmental effects of integrating switch grass for bioenergy into traditinal lololly pine silviculture in the US Southeast. Likewise, project results educated state and federal regulatory agencies, industry representatives, and natural resources professionals. Results were commumicated to the scientific community in a total of 44 publications and professional presentations to date, with four more expected over the next two years. In summary, we found that it is possible to produce meaningful amounts of switch grass using relatively low input technology without adversely affecting pine productivity. Rates of switch grass productivity averaged 4-6 tons per acre per year, which is less than hoped for (~10 tons per acre per year), however, before this experiment it was unknown if switch grass could be produced in a pineplantation setting. We believe that with more research, there is great potential to increaseswitch grass intercropping productivity greatly, especially as newimproved varieties of the grass have been developed sincethis project was initiated. Siginficantly, our research also demonstrated that the switch grass intercrop uses no more water than naturally competing vegetation in pine plantations. Thus, this new cropping system has potential to greatly increase the water use efficiency of the system by producing both a tree crop and a grass crop with total site evapotranspriation remaining unchanged from conventional pine management. These latter results are currently being synthesized for publication in the coming months.

Publications

• Type: Journal Articles Status: Published Year Published: 2012 Citation: Albaugh, J.A., Sucre, E.B., Leggett, Z.H., Domec, J.C., and King, J.S. 2012. Evaluation of intercropped switchgrass establishment under a range of experimental site preparation treatments in a forested setting on the Lower Coastal Plain of North Carolina, U.S.A. Biomass and Bioenergy 46: 473:482.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: King, J.S., Ceulemans, R., Albaugh, J.M., Dillen, S.Y., Domec J-C, Fichot, R., Fischer, M.,Leggett, Z., Sucre E., Trnka, M. and Zenone. 2013. The challenge of ligno-cellulosic bioenergy in a water-limited world. BioScience 63: 102-117.
• Type: Journal Articles Status: Published Year Published: 2012 Citation: Minick, K. J., T. R. Fox, B. D. Strahm, E. B. Sucre, and Z. H. Leggett. 2012. Soil organic matter fractions in loblolly pine forests of Coastal North Carolina. Forest Productivity Cooperative Annual Research Summary
• Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: Nichols, L. K., T. R. Fox, B.D. Strahm, J.R. Seiler, E.B. Sucre, and Z. H. Leggett. 2012. The impact of low molecular weight organic acid and dissolved organic carbon on microbial biomass in a loblolly pine and switchgrass intercropped system. Forest Productivity Cooperative Annual Research Summary.
• Type: Book Chapters Status: Published Year Published: 2013 Citation: King JS, Liu L, Aspinwall MJ (2013) Tree and forest responses to interacting elevated atmospheric CO2 and tropospheric O3: A synthesis of experimental evidence. In Matyssek R, Clarke N, Cudlin P, Mikkelsen TN, Tuovinen J-P, Wieser G, Paoletti E (eds) Climate change, air pollution and global challenges: Understanding solutions from forest research, Elsevier Physical Sciences Series, San Diego, pp. 179-208.
• Type: Theses/Dissertations Status: Published Year Published: 2013 Citation: Nichols, Lara . 2013. Soil CO2 Efflux, Dissolved Organic Carbon, Root Exudates and Microbial Community Dynamics in a Loblolly Pine and Switchgrass Intercropped System Located on the North Carolina Coastal Plain. MS Thesis, Virginia Tech, Blacksburg, Va, p. 80.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: King JS, Domec J-C, Fischer M, Stape J, Leggett Z, Sucre E, Johnsen K, Maier C, Seiler J, Fox T, Strahm B (2014) Pine-switchgrass intercropping for sustainable timber and biofuels production. USDA NIFA Annual Investigators Meeting, Washington, D.C., 29-31 October.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: King JS (2014) The challenge of lignocellulosic bioenergy in a water-limited world. Department of Ecology, Munich Technical University, Freising, Germany, 30 June. Invited.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Dome J-C, Noormets A, King JS, Radecki A, Sun G, McNulty S, Miao G (2014) Aquaporin-mediated reduction in loblolly pine root hydraulic conductivity impacts whole-stand water use and carbon assimilation. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.
• Type: Theses/Dissertations Status: Published Year Published: 2013 Citation: Shrestha, Paliza. 2013. Greenhouse gas fluxes and root productivity in a switchgrass and loblolly pine intercropping system for bioenergy production. MS Thesis, Virginia Tech, Blacksburg, Va, p. 65.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Tian H, Lu C, Pan S, Yang Q, Sun G, King J (2014) Potential impacts of cellulosic biofuel production on water use and yield in the United States: Perspectives from a process-based ecosystem model. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.
• Type: Theses/Dissertations Status: Published Year Published: 2014 Citation: Minick, Kevan J. 2014. Belowground carbon and nitrogen cycling in a loblolly pine forest managed for bioenergy production. PhD Dissertation, Virgina Tech, Blacksburg, Va, p. 121
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Albaugh JM, Domec J-C, Maier CA, Sucre EB, Leggett ZH, King JS (2014) Gas exchange and stand-level estimates of water use and gross primary productivity in an experimental pine and switch grass intercrop forestry system on the Lower Coastal Plain of North Carolina, USA. Agricultural and Forest Meteorology 192-193: 27-40.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: King JS, Kelley AM, Rees R (2014) Systemic control of Nantucket pine tip moth (Rhyacionia frustrana Scudder in Comstock, 1880) enhances seedling vigor, plantation establishment and early stand-level productivity in Pinus taeda L. Forest Science 60: 97-108.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Minick KJ, Strahm BD, Fox TR, Sucre EB, Leggett ZH, Zerpa JL (2014) Switch grass intercropping reduces soil inorganic nitrogen in a young loblolly pine plantation located in coastal North Carolina. Forest Ecology and Management 319: 161-168.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Tian S, Youssef MA, Sun G, Chescheir GM, Noormets A, Amatya AM, Skaggs RW, King JS, McNulty S, Gavazzi M, Miao G, Domec J-C (2015) Testing DRAINMOD-FOREST for predicting evapotranspiration in a mid-rotation pine plantation. Forest Ecology and Management 355: 37-47.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Domec J-C, Albaugh JM, Maier CM, Sucre EB, Leggett ZH, King JS (2014) Parameterization of process-based models to project effects of climate change on water use and carbon assimilation of switch grass (Panicum virgatum L.) when grown as a forest intercrop. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: King JS (2014) Creating a geographically distributed research network for development of climatically robust, sustainable bioenergy systems. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: ) Albaugh JM, Albaugh TJ, Heiderman RR, Leggett Z, Stape JL, King K, ONeill KP, King JS (2014) Evaluating changes in switch grass physiology, biomass, and light-use efficiency under artificial shade to estimate yields if intercropped with Pinus taeda L. Agroforestry Systems 88: 489-503.
• Type: Journal Articles Status: Published Year Published: 2013 Citation: Albaugh JM, Dye PJ, King JS (2013) Eucalyptus and water use in South Africa. International Journal of Forestry Research 852540, 11 p.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Albaugh JM, Albaugh TJ, Heiderman RR, Leggett Z, Stape JL, King K, ONeill KP, King JS (2014) Evaluating changes in switch grass physiology, biomass, and light-use efficiency under artificial shade to estimate yields if intercropped with Pinus taeda L. Agroforestry Systems 88: 489-503.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Domec J-C, King JS, Ward E, Oishi C, Palmroth S, Radecki A, Bell DM, Miao G, Gavazzi M, Johnson DM, McNulty SG, Sun G, Noormets A (2015) Conversion of natural forests to managed forest plantations decreases tree resistance to prolonged droughts. Forest Ecology and Management 355: 58-71.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Ward EJ, Domec J-C, Laviner MA, Fox TR, Sun G, McNulty S, King J, Noormets A (2015) Fertilization intensifies drought stress: Water use and stomatal conductance of Pinus taeda in a midrotation fertilization and thoughfall reduction experiment. Forest Ecology and Management 355: 72-82.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Noormets A, Epron D, Domec JC, McNulty SG, Fox TR, Sun G, King JS (2015) Effects of forest management on productivity and carbon sequestration: A review and hypothesis. Forest Ecology and Management 355: 124-140.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: King JS, Fischer M, Domec J-C, Williamson J, Sucre E (2015) Quantification of linked carbon and water cycles in a loblolly pine-switch grass intercropping system for bioenergy and wood products. Euforia: European Forest Research and Innovation Area, The final EUROFINNO conference, Rogla, Slovenia, 31 August  4 September.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Fischer M, Noormets A, Domec J-C, Rosa R, Williamson J, Boone J, Sucre E, Trnka M, King JS (2015) Evapotranspiration of a pine-switch grass intercropping bioenergy system measured by surface renewal and energy balance methods. American Geophysical Union Annual Meeting, San Francisco, CA, 14-18 December.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: King JS, Fischer M, Domec J-C, Sucre E Johnsen K, Maier C, Eaton R, Seiler J, Fox T, Strahm B (2015) Pine-switch grass intercropping for sustainable timber and biofuels production. USDA NIFA Sustainable Bioenergy Annual Investigator Meeting, Denver, Colorado, 2-5 November.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Fischer M, Domec J-C, Noormets A, Williamson J, Boone J, Sucre E, Trnka M, King JS (2015) Testing the surface renewal technique to quantify evapotranspiration of switch grass. USDA NIFA Sustainable Bioenergy Annual Investigator Meeting, Denver, Colorado, 2-5 November.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Kelley A, King JS (2014) Pest pressure, hurricanes, and genotype interact to strongly impact stem form in young loblolly pine (Pinus taeda L.) along the coastal plain of North Carolina. Trees Structure and Function 28: 1343-1353.
• Type: Journal Articles Status: Published Year Published: 2016 Citation: Tian S, Cacho JF, Youssef MA, Chescheir GM, Fischer M, Nettles JE, King JS (2016) Switchgrass growth and pine-switchgrass interactions in established cropping systems. Global Change Biology Bioenergy doi: 10.1111/gcbb.12381
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Fischer M, Kelley AM, Ward EJ, Boone JD, Ashley EM, Domec J-C, Williamson JC, King JS (2017) A critical analysis of species selection and high vs. low input silviculture on establishment success and early productivity of model short-rotation wood-energy cropping systems. Biomass and Bioenergy 98: 214-227.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Matyssek R, Kozovits AR, Wieser G, King J, Rennenberg H (2017) Woody plant ecosystems under climate change and air pollution: Response consistencies across zonobiomes? Tree Physiology DOI:10.01093/treephys/tpx009.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Fischer M, Zenone T, Trnka M, Orsag M, Montagnani L, Ward EJ, Tripathi AM, Hlavinka P, Seuf ert G, Zalud Z, King JS, Ceulemans R (2018) Water requirements of short rotation coppice: Experimental and modelling analyses across Europe. Agricultural Forest Meteorology, https://doi.org/10.1016/j.agformet.201712.079.
• Type: Journal Articles Status: Accepted Year Published: 2018 Citation: Tian S, Fischer M, Chescheir GM, Youssef MA, Cacho JF, King JS (2018) Microtopography-induced transient waterlogging affects switchgrass (Alamo) growth in the Lower Coastal Plain of North Carolina, USA. Global Change Biology Bioenergy, in press.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Fischer M, Katul G, Williamson J, Domec J-C, Tian S, Chescheir G, Youssef M, King J (2017) Evapotranspiration of pine-switchgrass intercropping bioenergy system in the lower coastal plain of North Carolina, USA. USDA NIFA Bioeconomy Project Directors Meeting, Tampa FL, 20-23 October.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Eaton B, Maier C, Johnsen K, King J (2017) Effects of pine and switchgrass intercropping on biomass production in a loblolly pine (Pinus taeda L.) plantation on a coastal plain site in North Carolina. 19th Biennial Southern Silviculture Research Conference, Blacksburg, VA, 13-16 March.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Fischer M, Katul GG, Noormets A, Poznikova G, Domec J-C, Trnka M, King JS (2016) Evaluation of surface renewal and flux-variance methods above agricultural and forest surfaces. American Geophysical Union Annual Meeting, San Francisco, CA, 12-16, December.

Progress 03/15/17 to 03/14/18

Outputs
Target Audience:Target audiences include undergraduate and graduate students at NCSU and Virginia Tech, Forest Service scientists and program administrators of the Southern Research Station, Weyerhaeuser technical staff and research silviculturists, state and federal program managers, and the broader scientific community. Approximately 150 undergraduate and graduate students learned about advanced bioenergy science in courses taught by project PIs King, Strahm, and Seiler on forest soils, forest ecophysiology and silviculture, and in departmental seminars. Results of this project were communicated to Forest Service research staff and interested program administrators through regular staff meetings and retreats. Weyerhaeuser technical and research staff were apprised of project progress, operational issues, and results through regular email discussions, conference calls, and field site visits. State program managers, in particular from the NC Dept of Agriculture, were apprised of project progress through regular meetings. The broader scientific community was reached through presentations of results at international scientific meetings and publications. The number reached by this method is inestimbable, but number at least in the hundreds. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Professional development opportunities were provided to undergraduate and graduate students enrolled in natural resources management curricula at NCSU and Virginia Tech universities. These opportunities primarily took the form of lecture-based courses in forest ecophysiology and productivity, forest soil science, and natural resources management. We also provided advanced scientific research training opportunities to undergraduate students who work on the project as research assistants/technicians. Undergraduate research assistants at NCSU were: Dominic Manz, Wesley Harris, Jordan Luff, Connor Nesbitt, and Collin Powers. More advanced training in experimental design, measurement methodology, statistical data analysis, scientific writing and professional development were provided to graduate students and postdoctoral research fellows associated with the project. Two postdoctoral associates, Dr. Kevan Minick and Dr. Xuefeng Li, received advanced training in forest ecophsiology and scientific career training. . Information provided by our work is directly relevant to Weyerhaeuser NR Company and other bioenergy professionals to inform management and business decisions. Results of this project are also being used to parameterize ecosystem models that will be incorporated into decision support systems by the USDA Forest Service Southeast Regional Climate Hub that will translate scientific knowledge on natural/managed ecosystem responses to environmental change to end-users, including farmers, forest products industry, state agricultural/forestry agencies, etc. How have the results been disseminated to communities of interest?Results have been disseminated through peer-reviewed publications, professional meeting presentations, undergraduate and graduate classroom instruction, natural resources agency training workshops, media outlets, and K-12 educational outreach events. What do you plan to do during the next reporting period to accomplish the goals?This is the last reporting periood. Therefore, a final project report will be submitted concluding reporting requirements for this project. The final report will summarize all project activities, accomplishments, and products.

Impacts
What was accomplished under these goals? This reporting period (2017-2018) represented the end of the project under a no-cost extension that was granted in Year 5 of the project. This last year was dedicated to terminatingfield activities, data management and analysis, and publication of results in peer-reviewed scientific publications. Termination of field activities involved removal of all instrumentation and equipment from the operational pine plantation land owned and operated by our industry collaborator, Weyerhaeuser NR Company. Equipment removed included the towers for surface renewal/eddy covariance studies, micrometeorology, sapflow probes and associated solar power supply systems, minirhizotron tubes and soil water content probes, soil thermocouples, and associated data logging equipment. This array of equipment/instruments was deployed for five years, collecting data to allow us to accomplish Objectives 1-4 listed above. The project has published a total of 16 peer-reviewed publications and two graduate theses relating to productivity, and the cycling of carbon, nutrientsand waterof intercropping switch grass into traditonal loblolly pine management. Analyses are ongoing in preparation of approximately four more peer-reviewed publications in fulfillment of the project goals and objectives. These papers are anticipated to be published over the next two years, reprints of which will be forward to USDA NIFA Sustainable Bioenergy programmanagers upon completion.

Publications

• Type: Journal Articles Status: Published Year Published: 2016 Citation: Tian S, Cacho JF, Youssef MA, Chescheir GM, Fischer M, Nettles JE, King JS (2016) Switchgrass growth and pine-switchgrass interactions in established cropping systems. Global Change Biology Bioenergy doi: 10.1111/gcbb.12381
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Fischer M, Kelley AM, Ward EJ, Boone JD, Ashley EM, Domec J-C, Williamson JC, King JS (2017) A critical analysis of species selection and high vs. low input silviculture on establishment success and early productivity of model short-rotation wood-energy cropping systems. Biomass and Bioenergy 98: 214-227.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Matyssek R, Kozovits AR, Wieser G, King J, Rennenberg H (2017) Woody plant ecosystems under climate change and air pollution: Response consistencies across zonobiomes? Tree Physiology DOI:10.01093/treephys/tpx009.
• Type: Journal Articles Status: Published Year Published: 2018 Citation: Fischer M, Zenone T, Trnka M, Orsag M, Montagnani L, Ward EJ, Tripathi AM, Hlavinka P, Seuf ert G, Zalud Z, King JS, Ceulemans R (2018) Water requirements of short rotation coppice: Experimental and modelling analyses across Europe. Agricultural Forest Meteorology, https://doi.org/10.1016/j.agformet.201712.079.
• Type: Journal Articles Status: Accepted Year Published: 2018 Citation: Tian S, Fischer M, Chescheir GM, Youssef MA, Cacho JF, King JS (2018) Microtopography-induced transient waterlogging affects switchgrass (Alamo) growth in the Lower Coastal Plain of North Carolina, USA. Global Change Biology Bioenergy, in press.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Fischer M, Katul G, Williamson J, Domec J-C, Tian S, Chescheir G, Youssef M, King J (2017) Evapotranspiration of pine-switchgrass intercropping bioenergy system in the lower coastal plain of North Carolina, USA. USDA NIFA Bioeconomy Project Directors Meeting, Tampa FL, 20-23 October.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2017 Citation: Eaton B, Maier C, Johnsen K, King J (2017) Effects of pine and switchgrass intercropping on biomass production in a loblolly pine (Pinus taeda L.) plantation on a coastal plain site in North Carolina. 19th Biennial Southern Silviculture Research Conference, Blacksburg, VA, 13-16 March.
• Type: Conference Papers and Presentations Status: Accepted Year Published: 2016 Citation: Fischer M, Katul GG, Noormets A, Poznikova G, Domec J-C, Trnka M, King JS (2016) Evaluation of surface renewal and flux-variance methods above agricultural and forest surfaces. American Geophysical Union Annual Meeting, San Francisco, CA, 12-16, December.

Progress 03/15/16 to 03/14/17

Outputs
Target Audience:Target audiences includeundergraduate and graduate students at NCSU and Virginia Tech, Forest Service scientists and program administrators of the Southern Research Station, Weyerhaeuser technical staff and research silviculturists, state and federal program managers, and the broader scientific community. Approximately 125 undergraduate and graduate students learned about advanced bioenergy science in courses taught by project PIs King, Strahm, and Seiler on forest soils, forest ecophysiology and silviculture, and in departmental seminars. Results of this project were communicated to Forest Service research staff and interested program administrators through regular staff meetings and retreats. Weyerhaeuser technical and research staff were apprised of project progress, operational issues, and results through regular email discussions, conference calls, field site visits, and a 2 day workshop held at NC State University in March. State program managers, in particular from the NC Dept of Agriculture, were apprised of project progress through regular meetings. Federal program managers, in particular, program personnel and other project PI's funded by the NIFA Sustainable Bioenergy program were engaged during the Annual Investigators meeting. The broader scientific community was reached through presentations of results at international scientific meetings and publications. The number reached by this method is inestimbable, but number at least in the hundreds. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Professional development opportunities were provided to undergraduate students enrolled in natural resources management curricula at NCSU and Virginia Tech universities. These opportunities primarily took the form of lecture-based courses in forest ecophysiology and productivity, forest soil science, and natural resources management. We also provided advanced scientific research training opportunities to undergraduate students who work on the project as research assistants/technicians. Undergraduate research assistants at NCSU were: Dominic Manz, Wesley Harris, Jordan Luff, Connor Nesbitt, and Collin Powers. More advanced training in experimental design, measurement methodology, statistical data analysis, scientific writing and professional development were provided to graduate students and postdoctoral research fellows associated with the project. Two postdoctoral associates, Dr. Milan Fischer and (new) Dr. Kevan Minick, received advanced training in forest ecophsiology and scientific career training. . Information provided by our work is directly relevant to Weyerhaeuser NR Company and other bioenergy professionals to inform management and business decisions. Results ofthis project are also being used to parameterize ecosystem models that will be incorporated into decision support systems by the USDA Forest Service Southeast RegionalClimate Hubthat will translate scientific knowledge on natural/managed ecosystem responses to environmental change to end-users, including farmers, forest products industry, state agricultural/forestry agencies, etc. How have the results been disseminated to communities of interest?Results have been disseminated through peer-reviewed publications, professional meeting presentations, undergraduate and graduate classroom instruction, natural resources agency training workshops, media outlets, and K-12 educational outreach events. What do you plan to do during the next reporting period to accomplish the goals?This reporting period completedthe fith year of the project (originally a 5 year project). Because we added new technologies and methods from those originally proposed (minirhizotron study of root dynamics, surface renewal of ET water flux and partitioning). We requested/received a NCE for a 6th year of measurements. During this 6th year of the project, we will continue to collect data on site meterology and soil conditions (temperature and water content, groundwater dyanmics), tree and grass productivity, root dynamics, canopy and water fluxes using eddy-covariance and surface renewal methods. At the end of this year (Year 6), we will dismantle the site, removing all equipment from the field site, so that our industry collaboratory (Weyerhaeuser NR Company) can resume commercial timber operations.

Impacts
What was accomplished under these goals? During this reporting period (2015-2016), field operations and management of the experiment continued in a manner consistent with previous years. Growing conditions were good this year, if not somewhat dry, and issues of diseases that occurred in past years (brown needle cast and pitch canker) were not evident. Automated data collection of on-site micrometeorology, soil temperature and moisture was ongoing. The phenology of switch grass biomass production was estimated with several clip-plot campaigns distributed evenly across the growing season (April-October), and a total switch grass harvest was completed at the end of the 2016growing season. Tree diameter and height measurements, and allometric biomass estimation were also conducted as in previous years. Granier-style sap flow probes were installed in spring 2011 and are still being continuously updated/maintained/monitored, with data downloaded on a monthly basis. Pine phenology measurements were collected in March and August, and 32 (8 per plot) representative needle samples were collected from trees in the outer plot for calculation of leaf area per tree. Diurnal (pre-dawn until 4 pm) gas exchange (photosynthesis and stomatal conductance) and water potential values were measured in April, September and October. Gas exchange was measured with a LI-6400 portable photosynthesis system (Licor, Inc., Lincoln, NE), and a PMS Model 1000 pressure bomb (PMS Instrument Co., Albany, OR ) was used to measure water potential. These photosynthetic and hydraulic variables were used to parameterize the soil plant atmosphere model (SPA). These variables will help us determine the effect of pine and intercropping crops on whole site water uptake and carbon balance. The soil C cycling studies conducted by the Virginia Tech team were completed in 2014, and activity in this realm was restricted to final data analysis and work on publications. The twonew lines of investigation begun in the past reporting period, were continued with great success during this reporting period. Thestudy on fine root phenology/dynamics using minirhizotrons (MR) is being conducted by a new MS student, Mr. James Williamson. He has installed and is now monitoring 50 cm MR tubes in bed, and interbed locations in all treatments to observe the seasonal patterns of grass and tree fine root production and mortality. Results will quantify belowground C inputs to soil and help to understand depth distributions of roots of the two vegetation types. Destructive sampling accompanies this work to characterize the seasonal biochemistry of roots to understand above- and belowground allocation of C and N, and root litter biochemical quality. These data on C and N allocaton will be used to parameterize an ecosystem model of productivity and water cycling. The second new study is use of the surface renewal (SR) systems method in all treatments to quantify and partition between trees and grass the stand level water use or evapotranspiration (ET). The system wasbeing calibrated/verified against tree sap flow measurements and eddy covariance measurements, and appears to compare favorably to these more traditional methods. Advantages of SR over eddy covariance for estimating water flux include significant cost savings, greater ease of use/simpler technology, and smaller fetch area required. Early results of both studies have been presented at scientific meetings, seminars, and classroom instruction.

Publications

• Type: Conference Papers and Presentations Status: Other Year Published: 2015 Citation: Fischer M, Domec J-C, Noormets A, Williamson J, Boone J, Sucre E, Trnka M, King JS (2015) Testing the surface renewal technique to quantify evapotranspiration of switch grass. USDA NIFA Sustainable Bioenergy Annual Investigator Meeting, Denver, Colorado, 2-5 November.
• Type: Conference Papers and Presentations Status: Other Year Published: 2015 Citation: King JS, Fischer M, Domec J-C, Sucre E Johnsen K, Maier C, Eaton R, Seiler J, Fox T, Strahm B (2015) Pine-switch grass intercropping for sustainable timber and biofuels production. USDA NIFA Sustainable Bioenergy Annual Investigator Meeting, Denver, Colorado, 2-5 November.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Albaugh JM, Albaugh TJ, Heiderman RR, Leggett Z, Stape JL, King K, ONeill KP, King JS (2014) Evaluating changes in switch grass physiology, biomass, and light-use efficiency under artificial shade to estimate yields if intercropped with Pinus taeda L. Agroforestry Systems 88: 489-503.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Domec J-C, King JS, Ward E, Oishi C, Palmroth S, Radecki A, Bell DM, Miao G, Gavazzi M, Johnson DM, McNulty SG, Sun G, Noormets A (2015) Conversion of natural forests to managed forest plantations decreases tree resistance to prolonged droughts. Forest Ecology and Management 355: 58-71.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Ward EJ, Domec J-C, Laviner MA, Fox TR, Sun G, McNulty S, King J, Noormets A (2015) Fertilization intensifies drought stress: Water use and stomatal conductance of Pinus taeda in a midrotation fertilization and thoughfall reduction experiment. Forest Ecology and Management 355: 72-82.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Tian S, Youssef MA, Sun G, Chescheir GM, Noormets A, Amatya AM, Skaggs RW, King JS, McNulty S, Gavazzi M, Miao G, Domec J-C (2015) Testing DRAINMOD-FOREST for predicting evapotranspiration in a mid-rotation pine plantation. Forest Ecology and Management 355: 37-47.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Noormets A, Epron D, Domec JC, McNulty SG, Fox TR, Sun G, King JS (2015) Effects of forest management on productivity and carbon sequestration: A review and hypothesis. Forest Ecology and Management 355: 124-140.
• Type: Conference Papers and Presentations Status: Other Year Published: 2015 Citation: King JS, Fischer M, Domec J-C, Williamson J, Sucre E (2015) Quantification of linked carbon and water cycles in a loblolly pine-switch grass intercropping system for bioenergy and wood products. Euforia: European Forest Research and Innovation Area, The final EUROFINNO conference, Rogla, Slovenia, 31 August  4 September.
• Type: Conference Papers and Presentations Status: Other Year Published: 2015 Citation: Fischer M, Noormets A, Domec J-C, Rosa R, Williamson J, Boone J, Sucre E, Trnka M, King JS (2015) Evapotranspiration of a pine-switch grass intercropping bioenergy system measured by surface renewal and energy balance methods. American Geophysical Union Annual Meeting, San Francisco, CA, 14-18 December.

Progress 03/15/15 to 03/14/16

Outputs
Target Audience:Target audiences for products of this project during this reporting period included undergraduate and graduate students at NCSU and Virginia Tech, Forest Service scientists and program administrators of the Southern Research Station, Weyerhaeuser technical staff and research silviculturists, state and federal program managers, and the broader scientific community. Approximately 125 undergraduate and graduate students learned about advanced bioenergy science in courses taught by project PIs King, Strahm, and Seiler on forest soils, forest ecophysiology and silviculture, and in departmental seminars. Results of this project were communicated to Forest Service research staff and interested program administrators through regular staff meetings and a 2 day retreat. A total of 15 Forest Service personnel were engaged. Weyerhaeuser technical and research staff were apprised of project progress, operational issues, and results through regular email discussions, conference calls, field site visits, and a 2 day workshop held at Weyerhaeuser corporate headquarters in New Bern, NC, in November, 2013. We interacted with approximately 50 staff and scientists associated with Weyerhaeusr NR Company in this capacity. State program managers, in particular from the NC Dept of Agriculture, were apprised of project progress through regular meetings. Two persons were engaged in this manner. Federal program managers, in particular, program personnel and other project PI's funded by the NIFA Sustainable Bioenergy program were engaged during the fall 2013 Annual Investigators meeting. However, due to the shutdown of the Federal government during this time, the audience was much reduced, especially by federal employees who could not travel/work. The broader scientific community was reached through presentations of results at international scientific meetings and publications. The number reached by this method is inestimbable, but number at least in the hundreds. Changes/Problems:During this project year the main changes to the project were addition of new personnel and associated projects. Mr. James Williamson joined the project as an MS student working on fine root dynamics of tree and grass crops, root biochemistry, and seasonal phenology of above- and below-ground C allocation. He is mainly supported by other funding, but his results will be directly relevant to this project. Dr. Milan Fischer joined the project in summer 2014 and is an expert in tree water relations and quantification of stand-level ET. He is adding a new component to the project to better estimate total stand ET, and partition it between the tree and grass crop species. His data will provide a crucial independent check on the SPA model parameterization (Albaugh et al. 2014) that we accomplished in earlier work, as well as being used to close the site water balance, and parameterize additional models for scaling water fluxes to larger spatial scales. During this project year, growing conditions were good and there were no problems with pests/pathogens, etc. What opportunities for training and professional development has the project provided?Professional development opportunities were provided to undergraduate students enrolled in natural resources management curricula at NCSU and Virginia Tech universities. These opportunities primarily took the form of lecture based courses in forest ecophysiology and productivity science, forest soil science, and natural resources management. We also provided advanced scientific research training opportunities to undergraduate students who work on the project as research assistants/technicians. Undergraduate research assistants at NCSU were: James Williamson, Jameson Boone, Christian Owen, Abigail Kutcha, Thomas Hill, Kael Schlactus, Deanna Metivier, and Collin Powers. More advanced training in experimental design, measurement methodology, statistical data analysis, scientific writing and professional development were provided to graduate students and postdoctoral research fellows associated with the project. One undergraduate student technician, James Williamson, graduated from NCSU with a BS in Forestry in spring, 2015, and joined the project as an MS student this past year. Dr. Milan Fischer, who is an expert in plant water relations and micrometeorological methods to estimate ET, also joined the project this year. Dr. Kevan Minick graduate from Virginia Tech in 2014 and continues to work to get out the publications from his PhD work on the project. Information provided by our work is directly relevant to Weyerhaeuser NR Company and other bioenergy professionals to inform management and business decisions. Results of this project are also being used to parameterize ecosystem models that will be incorporated into decision support systems by the new USDA Forest Service National Climate Hubs that will translate scientific knowledge on natural/managed ecosystem responses to environmental change to end-users, including farmers, forest products industry, state agricultural/forestry agencies, etc. How have the results been disseminated to communities of interest?In publications and presentations listed under "products". What do you plan to do during the next reporting period to accomplish the goals?This project is now in Year 5 of a five year time line (end date 3/14/16). We will continue collecting field data for the remainder of 2015 and perform advanced data analysis and interpretation to parameterize the ecosystem models and generate publications. We have negotiated with Weyerhaeuser NR Company to extend the field experiment into 2016 field season, as they had made an internal decision to end the project in 2015 (contrary to our original agreement and proposal to USDA). An extra year of field measurements is needed to complete the fine root demography and SR ET partitioning studies initiated in 2015. In addition, due to scheduling conflicts we have not been able to travel to meet with modeling groups needed to parameterize the full family of models to scale results from the plant-level to the ecosystem to the region. This travel will occur over 2016. To accommodate these project needs, we will request a NCE for one year and a re-budget of remaining funds with a new end date of 3/14/17.

Impacts
What was accomplished under these goals? During this reporting period (2014-2015), field operations and management of the experiment continued in a manner consistent with previous years. Growing conditions were good this year, if not somewhat dry, and issues of diseases that occurred in past years (brown needle cast and pitch canker) were not evident. Automated data collection of on-site micro-meteorology, soil temperature and moisture was ongoing. The phenology of switch grass biomass production was estimated with several clip-plot campaigns distributed evenly across the growing season (April-October), and a total switch grass harvest was completed at the end of the 2015 growing season. The bales are currently being dried/weighed to estimate stand-level grass productivity. Tree diameter and height measurements, and allometric biomass estimation were also conducted as in previous years. Granier-style sap flow probes were installed in spring 2011 and are still being continuously updated/maintained/monitored, with data downloaded on a monthly basis. Pine phenology measurements were collected in March and August, and 32 (8 per plot) representative needle samples were collected from trees in the outer plot for calculation of leaf area per tree. Diurnal (pre-dawn until 4 pm) gas exchange (photosynthesis and stomatal conductance) and water potential values were measured in April, September and October. Gas exchange was measured with a LI-6400 portable photosynthesis system (Licor, Inc., Lincoln, NE), and a PMS Model 1000 pressure bomb (PMS Instrument Co., Albany, OR ) was used to measure water potential. These photosynthetic and hydraulic variables were used to parameterize the soil plant atmosphere model (SPA). These variables will help us determine the effect of pine and intercropping crops on whole site water uptake and carbon balance. The soil C cycling studies conducted by the Virginia Tech team were completed in 2014, and activity in this realm was restricted to final data analysis and work on publications. Two new lines of investigation were started during this reporting period. A study on fine root phenology/dynamics using minirhizotrons (MR) was begun. This involves installation of 50 cm MR tubes in bed, bed-interbed, and interbed locations in all treatments to observe the seasonal patterns of grass and tree fine root production and mortality. Results will quantify belowground C inputs to soil and help to understand depth distributions of roots of the two vegetation types. Destructive sampling accompanies this work to characterize the seasonal biochemistry of roots to understand above- and belowground allocation of C and N, and root litter biochemical quality. These data on C and N allocaton will be used to parameterize an ecosystem model of productivity and water cycling. A second new study involves the installation of surface renewal (SR) systems in all treatments to quantify and partition between trees and grass the stand level water use or evapotranspiration (ET). The system is being calibrated/verified against tree sap flow measurements and eddy covariance measurements. Advantages of SR over eddy covariance for estimating water flux include significant cost savings, greater ease of use/simpler technology, and smaller fetch area required. Early results are very promising.

Publications

• Type: Journal Articles Status: Published Year Published: 2014 Citation: Albaugh JM, Domec J-C, Maier CA, Sucre EB, Leggett ZH, King JS (2014) Gas exchange and stand-level estimates of water use and gross primary productivity in an experimental pine and switch grass intercrop forestry system on the Lower Coastal Plain of North Carolina, USA. Agricultural and Forest Meteorology 192-193: 27-40.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: King JS, Kelley AM, Rees R (2014) Systemic control of Nantucket pine tip moth (Rhyacionia frustrana Scudder in Comstock, 1880) enhances seedling vigor, plantation establishment and early stand-level productivity in Pinus taeda L. Forest Science 60: 97-108.
• Type: Theses/Dissertations Status: Published Year Published: 2014 Citation: Minick KJ, Strahm BD, Fox TR, Sucre EB, Leggett ZH, Zerpa JL (2014) Switch grass intercropping reduces soil inorganic nitrogen in a young loblolly pine plantation located in coastal North Carolina. Forest Ecology and Management 319: 161-168.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Tian S, Youssef MA, Sun G, Chescheir GM, Noormets A, Amatya AM, Skaggs RW, King JS, McNulty S, Gavazzi M, Miao G, Domec J-C (2015) Testing DRAINMOD-FOREST for predicting evapotranspiration in a mid-rotation pine plantation. Forest Ecology and Management 355: 37-47.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: King JS, Domec J-C, Fischer M, Stape J, Leggett Z, Sucre E, Johnsen K, Maier C, Seiler J, Fox T, Strahm B (2014) Pine-switchgrass intercropping for sustainable timber and biofuels production. USDA NIFA Annual Investigators Meeting, Washington, D.C., 29-31 October.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: King JS (2014) The challenge of lignocellulosic bioenergy in a water-limited world. Department of Ecology, Munich Technical University, Freising, Germany, 30 June. Invited.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Dome J-C, Noormets A, King JS, Radecki A, Sun G, McNulty S, Miao G (2014) Aquaporin-mediated reduction in loblolly pine root hydraulic conductivity impacts whole-stand water use and carbon assimilation. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Tian H, Lu C, Pan S, Yang Q, Sun G, King J (2014) Potential impacts of cellulosic biofuel production on water use and yield in the United States: Perspectives from a process-based ecosystem model. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Domec J-C, Albaugh JM, Maier CM, Sucre EB, Leggett ZH, King JS (2014) Parameterization of process-based models to project effects of climate change on water use and carbon assimilation of switch grass (Panicum virgatum L.) when grown as a forest intercrop. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: King JS (2014) Creating a geographically distributed research network for development of climatically robust, sustainable bioenergy systems. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.

Progress 03/15/14 to 03/14/15

Outputs
Target Audience:Target audiences for products of this project during this reporting period included undergraduate and graduate students at NCSU and Virginia Tech, Forest Service scientists and program administrators of the Southern Research Station, Weyerhaeuser technical staff and research silviculturists, state and federal program managers, and the broader scientific community. Approximately 125 undergraduate and graduate students learned about advanced bioenergy science in courses taught by project PIs King, Strahm, and Seiler on forest soils, forest ecophysiology and silviculture, and in departmental seminars. Results of this project were communicated to Forest Service research staff and interested program administrators through regular staff meetings and a 2 day retreat. A total of 15 Forest Service personnel were engaged. Weyerhaeuser technical and research staff were apprised of project progress, operational issues, and results through regular email discussions, conference calls, field site visits, and a 2 day workshop held at Weyerhaeuser corporate headquarters in Raleigh, NC, in February, 2015. State program managers, in particular from the NC Dept of Agriculture, were apprised of project progress through regular meetings. Two persons were engaged in this manner. Federal program managers, in particular, program personnel and other project PI's funded by the NIFA Sustainable Bioenergy program were engaged during the fall 2014 Annual Investigators meeting. The broader scientific community was reached through presentations of results at international scientific meetings and publications. The number reached by this method is inestimable, but number at least in the hundreds. Changes/Problems:During this project year the main changes to the project were addition of new personnel and associated projects. Mr. James Williamson joined the project as an MS student working on fine root dynamics of tree and grass crops, root biochemistry, and seasonal phenology of above- and below-ground C allocation. He is mainly supported by other funding, but his results will be directly relevant to this project. Dr. Milan Fischer joined the project in summer 2014 and is an expert in tree water relations and quantification of stand-level ET. He is adding a new component to the project to better estimate total stand ET, and partition it between the tree and grass crop species. His data will provide a crucial independent check on the SPA model parameterization (Albaugh et al. 2014) that we accomplished in earlier work, as well as being used to close the site water balance, and parameterize additional models for scaling water fluxes to larger spatial scales. During this project year, growing conditions were good and there were no problems with pests/pathogens, etc. What opportunities for training and professional development has the project provided?Professional development opportunities were provided to undergraduate students enrolled in natural resources management curricula at NCSU and Virginia Tech universities. These opportunities primarily took the form of lecture based courses in forest ecophysiology and productivity science, forest soil science, and natural resources management. We also provided advanced scientific research training opportunities to undergraduate students who work on the project as research assistants/technicians. Undergraduate research assistants at NCSU were: James Williamson, Jameson Boone, Christian Owen, Abigail Kutcha, Thomas Hill, Kael Schlactus, Deanna Metivier, and Collin Powers. More advanced training in experimental design, measurement methodology, statistical data analysis, scientific writing and professional development were provided to graduate students and postdoctoral research fellows associated with the project. One undergraduate student technician, James Williamson, graduated from NCSU with a BS in Forestry in spring, 2015, and joined the project as an MS student this past year. Dr. Milan Fischer, who is an expert in plant water relations and micrometeorological methods to estimate ET, also joined the project this year. Dr. Kevan Minick graduate from Virginia Tech in 2014 and continues to work to get out the publications from his PhD work on the project. Information provided by our work is directly relevant to Weyerhaeuser NR Company and other bioenergy professionals to inform management and business decisions. Results of this project are also being used to parameterize ecosystem models that will be incorporated into decision support systems by the new USDA Forest Service National Climate Hubs that will translate scientific knowledge on natural/managed ecosystem responses to environmental change to end-users, including farmers, forest products industry, state agricultural/forestry agencies, etc. How have the results been disseminated to communities of interest?In publications and presentations listed under "other products". What do you plan to do during the next reporting period to accomplish the goals?This project is now in Year 5 of a five year time line (end date 3/14/16). We will continue collecting field data for the remainder of 2015 and perform advanced data analysis and interpretation to parameterize the ecosystem models and generate publications. We have negotiated with Weyerhaeuser NR Company to extend the field experiment into 2016 field season, as they had made an internal decision to end the project in 2015 (contrary to our original agreement and proposal to USDA). An extra year of field measurements is needed to complete the fine root demography and SR ET partitioning studies initiated in 2015. In addition, due to scheduling conflicts we have not been able to travel to meet with modeling groups needed to parameterize the full family of models to scale results from the plant-level to the ecosystem to the region. This travel will occur over 2016. To accommodate these project needs, we will request a NCE for one year and a re-budget of remaining funds with a new end date of 3/14/17.

Impacts
What was accomplished under these goals? During this reporting period (2014-2015), field operations and management of the experiment continued in a manner consistent with previous years. Growing conditions were good this year, if not somewhat dry, and issues of diseases that occurred in past years (brown needle cast and pitch canker) were not evident. Automated data collection of on-site micro-meteorology, soil temperature and moisture was ongoing. The phenology of switch grass biomass production was estimated with several clip-plot campaigns distributed evenly across the growing season (April-October), and a total switch grass harvest was completed at the end of the 2015 growing season. The bales are currently being dried/weighed to estimate stand-level grass productivity. Tree diameter and height measurements, and allometric biomass estimation were also conducted as in previous years. Granier-style sap flow probes were installed in spring 2011 and are still being continuously updated/maintained/monitored, with data downloaded on a monthly basis. Pine phenology measurements were collected in March and August, and 32 (8 per plot) representative needle samples were collected from trees in the outer plot for calculation of leaf area per tree. Diurnal (pre-dawn until 4 pm) gas exchange (photosynthesis and stomatal conductance) and water potential values were measured in April, September and October. Gas exchange was measured with a LI-6400 portable photosynthesis system (Licor, Inc., Lincoln, NE), and a PMS Model 1000 pressure bomb (PMS Instrument Co., Albany, OR ) was used to measure water potential. These photosynthetic and hydraulic variables were used to parameterize the soil plant atmosphere model (SPA). These variables will help us determine the effect of pine and intercropping crops on whole site water uptake and carbon balance. The soil C cycling studies conducted by the Virginia Tech team were completed in 2014, and activity in this realm was restricted to final data analysis and work on publications. Two new lines of investigation were started during this reporting period. A study on fine root phenology/dynamics using minirhizotrons (MR) was begun. This involves installation of 50 cm MR tubes in bed, bed-interbed, and interbed locations in all treatments to observe the seasonal patterns of grass and tree fine root production and mortality. Results will quantify belowground C inputs to soil and help to understand depth distributions of roots of the two vegetation types. Destructive sampling accompanies this work to characterize the seasonal biochemistry of roots to understand above- and belowground allocation of C and N, and root litter biochemical quality. These data on C and N allocaton will be used to parameterize an ecosystem model of productivity and water cycling. A second new study involves the installation of surface renewal (SR) systems in all treatments to quantify and partition between trees and grass the stand level water use or evapotranspiration (ET). The system is being calibrated/verified against tree sap flow measurements and eddy covariance measurements. Advantages of SR over eddy covariance for estimating water flux include significant cost savings, greater ease of use/simpler technology, and smaller fetch area required. Early results are very promising.

Publications

• Type: Journal Articles Status: Published Year Published: 2014 Citation: Albaugh JM, Domec J-C, Maier CA, Sucre EB, Leggett ZH, King JS (2014) Gas exchange and stand-level estimates of water use and gross primary productivity in an experimental pine and switch grass intercrop forestry system on the Lower Coastal Plain of North Carolina, USA. Agricultural and Forest Meteorology 192-193: 27-40.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: King JS, Kelley AM, Rees R (2014) Systemic control of Nantucket pine tip moth (Rhyacionia frustrana Scudder in Comstock, 1880) enhances seedling vigor, plantation establishment and early stand-level productivity in Pinus taeda L. Forest Science 60: 97-108.
• Type: Journal Articles Status: Published Year Published: 2014 Citation: Minick KJ, Strahm BD, Fox TR, Sucre EB, Leggett ZH, Zerpa JL (2014) Switch grass intercropping reduces soil inorganic nitrogen in a young loblolly pine plantation located in coastal North Carolina. Forest Ecology and Management 319: 161-168.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Tian S, Youssef MA, Sun G, Chescheir GM, Noormets A, Amatya AM, Skaggs RW, King JS, McNulty S, Gavazzi M, Miao G, Domec J-C (2015) Testing DRAINMOD-FOREST for predicting evapotranspiration in a mid-rotation pine plantation. Forest Ecology and Management 355: 37-47.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: King JS, Domec J-C, Fischer M, Stape J, Leggett Z, Sucre E, Johnsen K, Maier C, Seiler J, Fox T, Strahm B (2014) Pine-switchgrass intercropping for sustainable timber and biofuels production. USDA NIFA Annual Investigators Meeting, Washington, D.C., 29-31 October.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: King JS (2014) The challenge of lignocellulosic bioenergy in a water-limited world. Department of Ecology, Munich Technical University, Freising, Germany, 30 June. Invited.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Dome J-C, Noormets A, King JS, Radecki A, Sun G, McNulty S, Miao G (2014) Aquaporin-mediated reduction in loblolly pine root hydraulic conductivity impacts whole-stand water use and carbon assimilation. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Tian H, Lu C, Pan S, Yang Q, Sun G, King J (2014) Potential impacts of cellulosic biofuel production on water use and yield in the United States: Perspectives from a process-based ecosystem model. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: Domec J-C, Albaugh JM, Maier CM, Sucre EB, Leggett ZH, King JS (2014) Parameterization of process-based models to project effects of climate change on water use and carbon assimilation of switch grass (Panicum virgatum L.) when grown as a forest intercrop. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.
• Type: Conference Papers and Presentations Status: Other Year Published: 2014 Citation: King JS (2014) Creating a geographically distributed research network for development of climatically robust, sustainable bioenergy systems. International Symposium on Evapotranspiration: Challenges in measurement and modeling from leaf to the landscape scale and beyond. American Society of Agricultural and Biological Engineers. Raleigh, NC, 7-10 April.

Progress 03/15/13 to 03/14/14

Outputs
Target Audience: Target audiences for products of this project during this reporting period included undergraduate and graduate students at NCSU and Virginia Tech, Forest Service scientists and program administrators of the Southern Research Station, Weyerhaeuser technical staff and research silviculturists,state andfederal program managers, and the broader scientific community. Approximately125 undergraduate and graduate students learned about advanced bioenergy science in courses taught by project PIs King, Strahm, and Seiler on forest soils, forest ecophysiology and silviculture, and in departmental seminars. Results of this project were communicated to Forest Serviceresearch staff and interestedprogram administrators through regular staff meetings and a 2 day retreat. A total of 15Forest Service personnel were engaged. Weyerhaeuser technicaland research staff were apprised of project progress,operational issues, and results throughregular email discussions, conference calls,field site visits, and a 2 day workshop heldat Weyerhaeusercorporate headquarters in New Bern, NC,in November, 2013. We interacted with approximately 50 staff and scientists associated with Weyerhaeusr NR Company in this capacity.State program managers, in particular from the NC Dept of Agriculture, were apprised of project progress through regular meetings. Two persons were engaged in this manner. Federal program managers, in particular, program personnel and other project PI's funded by the NIFA Sustainable Bioenergy program were engaged during the fall 2013 Annual Investigators meeting. However, due to the shutdown of the Federal government during this time, the audience was much reduced, especially by federal employees who could not travel/work.The broader scientific community was reached through presentations of results at international scientific meetings and publications. The number reached by this method is inestimbable, but number at least in the hundreds. Changes/Problems: During the last year of this project (e.g. this reporting period), two events impacted the project, not necessarily in negative ways, but in ways that may be expected to affect any bioenergy production system, and therefore, are realistic/worthwhile to incorporate. The first event, was that our original postodoctoral associate, Dr. Janinine Albaugh, chose to seek new career opportunities and left the project in December, 2013. This introduced a gap into the work flow, during which we advertised for/recruited a new postdoctoral associate, Dr. Milan Fischer, who will begin on 1 July, 2014. Dr. Fischer is a highly trained/competent scientist specializing in water use of bioenergy production systems, who will add much value to the project. The second unforeseen event was an uncharacteristically wet/coolgrowing season during spring/summer/fall of 2013. This resulted in lower than expected productivity of the pine tree and switch grass crops, and resulted in an infection of the trees by brown needle rust. Growing conditions so far during spring 2014 are much better, and the trees and grass both appear to beperforming better this year. Although such stochastic, natural events make it difficult to test the productivity potential of thisexperimental pine-switch grass bioenergy production system, they in fact make our resultsmore representative of operationalconditions and therefore a better basis upon which toevaluate this new industry (e.g. see King et al. 2013. BioScience 63:102-117). What opportunities for training and professional development has the project provided? Professional development opportunities were provided to undergraduate students enrolled in natural resources management curricula at NCSU and Virginia Tech universties. These opportunities primarily took the form of lecture based courses in forest ecophysiology and productivity science, forest soil science, and natural resources management.We also providedadvanced scientific research training opportunities to six undergraduate students who work on the project as research assistants/technicians.Undergraduate research assistantsat NCSU were: James Williams,Jameson Boone, Jacob Seyle, and Ian Thompson. Undergraduate research assistants at Virginia Tech were :William Kennerley and Chioma Ichoku. More advanced training in experimental design, measurement methodology, statistical data analysis, scientic writing and professional development were provided to graduate students and postdoctoral research fellows associated with the project.Four MS students at Virginia Tech received this training: Paliza Shrestha, Lori Nichols,Kevin Minnick, and Brett Rivers. One postdoc at NCSU received this training: Dr. Janine Albaugh.Information provided also is directly relevant to Weyerhaeuser NR Company and other bioenergy professionals to inform management and business decisions. Much technology transfer occurred when results were presented last November at theAssociation for Advancement of Industrial Crops professional meeting. Results of this project are also being used to parameterize ecosystem models that will be incorporated into decision support systems by the new USDA Forest Service National Climate Hubs that will translate scientific knowlege on natural/managed ecosystem responses to environmental change to end-users (farmers, forest products industry, state ag agencies, etc.). How have the results been disseminated to communities of interest? In publications andpresentations listed under "other products". What do you plan to do during the next reporting period to accomplish the goals? This project is now in Year 4 of a five year time line. We will continue collecting field data for the remainder of the year and begin/continue more advanced data analysis and interpretation to parameterize the ecosystem models and generate publications. We will continue to train undergraduate student technicians on the project and a new postdoctoral associate, who will begin on July 1, 2014. We expect field work to be fully completed by the end of 2015,and if necessary and funds permit, a 1 year no-cost extension will be requested for additional time to complete data analysis and publicationn/presentation of results.

Impacts
What was accomplished under these goals? Site management consistent with previous years, with no major changes in operations or experimental design. Automated data collection on site micro-meteorology and soil temperature/moisture ongoing. Switchgrass harvest this year was incompletedue to the wet winter preventing entry into the site and difficulty raking up the switch grass hay that had been cut. This resulted in uneven organic inputs to soil across the experiment, which much be accounted for in future studies/analyses. The trees have experienced some problems with brown needle cast andpitch canker but appear to have been recovering (spring 2014) due to better growing conditions compared to last year. Switchgrass biomass production was estimated with seven clip-plot campaigns distributed evenly across the growing season (April-October). Tree diameter and height measurements , and allometric biomass estimation, were also collected using the same sampling frequency. Several trees were harvested above- and belowground to generate the allometric biomass regressions. Sap flow measurements: Granier-style sap flow probes were installed in spring 2011 and are continuously monitored, with data downloaded on a monthly basis. Pine phenology measurements were collected in March and August, and 32 (8 per plot) representative needle samples were collected from trees in the outer plot for calculation of leaf area per tree.Diurnal (pre-dawn until 4 pm) gas exchange (photosynthesis and stomatal conductance) and water potential values were measured in April, September and October. Gas exchange was measured with a LI-6400 portable photosynthesis system (Licor, Inc., Lincoln, NE), and a PMS Model 1000 pressure bomb (PMS Instrument Co., Albany, OR )was used to measure water potential. These photosynthetic and hydraulic variables were used to parameterize the soil plant atmosphere model (SPA). These variables will help us determine the effect of pine and intercropping crops on whole site water uptake and carbon balance. Soil carbon and nitrogen dynamics Completed full yearly set of soil CO2 efflux measurements in pure switchgrass, pure pine minus residuals and pine-switch grass intercropped. Installed 35 cm root exclusion cores for estimating the contribution of heterotrophic and autotrophic soil reparation. These were installed twice (spring and summer). Measured pine and switchgrass roots to a depth of 35 cms using 10 cm diameter cores in spring and quarterly CH4 and N2O fluxes using vented static chambers. This was collected in the pure pine minus residuals (measured on bed and interbed areas) and pine-switch grass intercropped treatments. Coincident with soil CO2 efflux measurements every ~6 weeks, analyzed soils/soil solutions for microbial biomass and activity, dissolved organic carbon and nitrogen, inorganic nitrogen, and low molecular weight organic acids. Greenhouse study established last year comparing swith grass growth as a function of light interception wascompleted and the resulting manuscript is now in review at a journal.

Publications

• Type: Book Chapters Status: Published Year Published: 2013 Citation: King JS, Liu L, Aspinwall MJ (2013) Tree and forest responses to interacting elevated atmospheric CO2 and tropospheric O3: A synthesis of experimental evidence. In Matyssek R, Clarke N, Cudlin P, Mikkelsen TN, Tuovinen J-P, Wieser G, Paoletti E (eds) Climate change, air pollution and global challenges: Understanding solutions from forest research, Elsevier Physical Sciences Series, San Diego, pp. 179-208.
• Type: Theses/Dissertations Status: Accepted Year Published: 2013 Citation: Nichols, Lara . 2013. Soil CO2 Efflux, Dissolved Organic Carbon, Root Exudates and Microbial Community Dynamics in a Loblolly Pine and Switchgrass Intercropped System Located on the North Carolina Coastal Plain. MS Thesis, Virginia Tech, Blacksburg, Va, p. 80.
• Type: Theses/Dissertations Status: Accepted Year Published: 2013 Citation: Shrestha, Paliza. 2013. Greenhouse gas fluxes and root productivity in a switchgrass and loblolly pine intercropping system for bioenergy production. MS Thesis, Virginia Tech, Blacksburg, Va, p. 65.

Progress 03/15/12 to 03/14/13

Outputs
OUTPUTS: Site operations Site management consistent with previous years, with no major changes in operations or experimental design. Automated data collection on site micro-meteorology and soil temperature/moisture ongoing. Switchgrass harvest is still occurring (3-22-13) due to the wet winter preventing entry into the site. The trees have experienced some problems with tip moth, brown needle cast, droughts, pitch canker, and a hurricane (Sandy); the trees look somewhat stressed but not in danger of mortality. Biomass production studies Switchgrass biomass production was estimated with seven clip-plot campaigns distributed evenly across the growing season (April-October). Tree diameter and height measurements , and allometric biomass estimation, were also collected using the same sampling frequency. Several trees were harvested above- and belowground to generate the allometric biomass regressions. Water cycling studies Sap flow measurements: Granier-style sap flow probes were installed in spring 2011 and are continuously monitored, with data downloaded on a monthly basis. Pine phenology measurements were collected in March and August 2012, and 32 (8 per plot) representative needle samples were collected from trees in the outer plot for calculation of leaf area per tree. Diurnal gas exchange: Diurnal (pre-dawn until 4 pm) gas exchange (photosynthesis and stomatal conductance) and water potential values were measured in April, September and October 2012. Gas exchange was measured with a LI-6400 portable photosynthesis system (Licor, Inc., Lincoln, NE), and a PMS Model 1000 pressure bomb (PMS Instrument Co., Albany, OR ) was used to measure water potential. These photosynthetic and hydraulic variables will be used to parameterize the soil plant atmosphere model (SPA). These variables will help us determine the effect of pine and intercropping crops on whole site water uptake and carbon balance. Soil carbon and nitrogen dynamics Completed full yearly set of soil CO2 efflux measurements in pure switchgrass, pure pine minus residuals and pine-switch grass intercropped. Installed 35 cm root exclusion cores for estimating the contribution of heterotrophic and autotrophic soil reparation. These were installed twice (spring and summer). Measured pine and switchgrass roots to a depth of 35 cms using 10 cm diameter cores in spring and summer. This was collected in the pure switchgrass, pure pine minus residuals and pine-switch grass intercropped. Measured quarterly CH4 and N2O fluxes using vented static chambers. This was collected in the pure pine minus residuals (measured on bed and interbed areas) and pine-switch grass intercropped treatments. Coincident with soil CO2 efflux measurements every ~6 weeks, analyzed soils/soil solutions for microbial biomass and activity, dissolved organic carbon and nitrogen, inorganic nitrogen, and low molecular weight organic acids. Established a greenhouse study and monitored soil solutions for one year in order to determine the types and concentrations of root exudates (i.e., low molecular weight organic acids) associated with each species. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
At this point of the project, outcomes/impacts have mainly been communicated to the broader scientific community as presentations at regional/national/international scientific meetings. Presentations during reporting period: Albaugh JM, Domec J-C, Maier CA, Sucre EB, Leggett Z, King JS. Water relations in an intercropped pine-switchgrass study examining biofuel production in North Carolina, USA. Poster presentation at the World Bioenergy Conference, Elmia, Sweden, May 2012. Albaugh JM, Domec J-C, Maier CA, Sucre EB, Leggett Z, King JS. Water relations and productivity in an intercropped pine-switchgrass study examining biofuel production in North Carolina, USA, presented at the Sun Grant Initiative National Conference for Biomass Feedstock Production and Utilization, New Orleans, October 2-5, 2012. Albaugh JM, Domec J-C, King JS, Maier CA, Sucre EB, Leggett ZH. 2012. Water relations and water use in a pine-switchgrass intercropping stand grown for biofuel production on the Lower Coastal Plain of North Carolina, field presentation at Forest Productivity Cooperative Annual Research Meeting, October 18, 2012. King, J.S., Z.H. Leggett, E. B. Sucre, K. Johnson, C. Maier, J.C. Domec, J. Stape, J. Seiler, B. Strahm, T. Fox, and J. Albaugh. Loblolly pine-switchgrass intercropping for sustainable timber and biofuels production. Poster presentation at the 2012 ASA-CSSA-SSSA International Annual Meetings, October 2012, Cincinnati, OH. Leggett, Z. H. and E.B. Sucre. Evaluating effects of biomass management and intercropping switchgrass in a managed pine forest on soil productivity and sustainability. Oral Presentation at the 2012 Soil Science Society of NC Meeting, January 2012. Raleigh, NC. Leggett, Z. H., E. Sucre, J. Nettles and D. Miller. Evaluating effects of intercropping pine plantations with switchgrass on soil productivity, water quality and quantity, and biodiversity. Oral Presentation at the 2012 Society of American Foresters National Convention. October 2012. Spokane, WA. Minick, K.J., B.D. Strahm, T.R. fox, E.B. Sucre. 2013. Carbon and nitrogen dynamics in a southern loblolly pine forest managed for simultaneous wood and bioenergy production. 7th Biennial Southern Silvicultural Research Conference, March 4 - 7, Shreveport, La. Nichols, L.K., B.D. Strahm, T.R. Fox, J.R. Seiler, Z.H. Leggett and E.B. Sucre. 2013. The impact of low molecular weight organic carbon on microbial biomass in a loblolly pine and switchgrass intercropped system. 7th Biennial Southern Silvicultural Research Conference, March 4 - 7, Shreveport, La. Shrestha, P., J.R. Seiler, B.D. Strahm. E.B. Sucre and Z.H. Leggett. 2013. Soil CO2, CH4 and N2O) fluxes in a switchgrass (Panicum virgatum L.) and loblolly pine (Pinus taeda L.) intercropping system. 17th Biennial Southern Silvicultural Research Conference, March 4 - 7, Shreveport, La.

Publications

• Albaugh, J.A., Sucre, E.B., Leggett, Z.H., Domec, J.C., and King, J.S. 2012. Evaluation of intercropped switchgrass establishment under a range of experimental site preparation treatments in a forested setting on the Lower Coastal Plain of North Carolina, U.S.A. Biomass and Bioenergy 46: 473:482.
• King, J.S., Ceulemans, R., Albaugh, J.M., Dillen, S.Y., Domec J-C, Fichot, R., Fischer, M.,Leggett, Z., Sucre E., Trnka, M. and Zenone. 2013. The challenge of ligno-cellulosic bioenergy in a water-limited world. BioScience 63: 102-117.
• Minick, K. J., T. R. Fox, B. D. Strahm, E. B. Sucre, and Z. H. Leggett. 2012. Soil organic matter fractions in loblolly pine forests of Coastal North Carolina. Forest Productivity Cooperative Annual Research Summary.
• Nichols, L. K., T. R. Fox, B.D. Strahm, J.R. Seiler, E.B. Sucre, and Z. H. Leggett. 2012. The impact of low molecular weight organic acid and dissolved organic carbon on microbial biomass in a loblolly pine and switchgrass intercropped system. Forest Productivity Cooperative Annual Research Summary.

Progress 03/15/11 to 03/14/12

Outputs
OUTPUTS: Overarching goal of this project is to develop a pine-switchgrass bioenergy production system for the southeastern U.S. based on regionally appropriate crops and indigenous biomass production practices that will benefit economic development and the environment. Emphasis is placed on understanding how this novel cropping system influences the interaction of carbon, nutrient and water cycles. Specific objectives and related outputs of the project are: 1) Quantify rates of tree and grass productivity alone and in combination; Soil moisture, soil temperature data has been continuously collected and summarized. Weather station data have been continuously collected since the study started. The experimental site and treatments have been maintained since project initiation. Switchgrass has been harvested, baled and weighed (fall 2011).Heights and diameters were measured on the trees as well as damage codes collected to assess effects from Hurricane Irene. Soil samples were collected pre- and post- senescence and data are being analyzed and processed. 2) Quantify cycling rates and sustainability of soil resources (nutrients, water, carbon (C)); For water: Granier-style sap flow probes were installed in spring 2011 and are continuously monitored. Pine phenology measurements were collected in May, July, September and November 2011. Representative needle samples were collected from trees for calculation of leaf area. The first set of phenology measurements for 2012 were completed in March. Diurnal (pre-dawn until 4 pm) gas exchange (photosynthesis and stomatal conductance) and water potential values were measured in June and October 2011. Diurnal data were collected from three replicate trees and three replicate switchgrass plants in the pine/switchgrass intercropped + biomass, and in the switchgrass-only plots in Blocks 1 and 2. These photosynthetic and hydraulic variables will be used to parameterize a soil plant atmosphere model (SPA). For soil carbon and nutrients: Secured both MS graduate students to work on specific grant objectives. Began measurements of soil CO2 efflux. Developed and tested root exclusion cores to partition heterotrophic and autotrophic respiration and are ready to deploy the cores in April 2012. Developed protocols for substrate induced respiration and chloroform fumigation. Constructed and tested soil greenhouse gas flux collars that are ready for deployment in March/April 2012. Customized isotope ratio mass spectrometer for 13CO2 analysis. Completed on year of measurement of plant nutrient availability using ion exchange resins. Developed soil organic matter fractionation methods; completed acid hydrolysis. Developed methods for gross mineralization and nitrification; first measurement to be made in March/April 2012.Started a controlled, greenhouse study to examine release of C and N from roots of pine and switchgrass. 3) Determine resource use efficiencies (light, nitrogen (N), water); To be determined from 1) and 2) later in the project. 4) Characterize C cycling and net C balance over the course of a full 25 year rotation. To be determined from 1) and 2) later in the project. PARTICIPANTS: North Carolina State University: PIs - Dr. J King, Dr. J-C Domec, Dr. J Stape; Postdoctoral Researcher - Dr. Janine Albaugh Virginia Tech University: PIs - Dr. B Strahm, Dr. J Seiler, Dr. T. Fox; Graduate Students - Laura Nichols, Paliza Shrestha, Kevan Minnick USDA Forest Service: PIs - Dr. Kurt Johnsen, Dr. Chris Maier; Research technicians - Tom Christensen, Bob Eaton Weyerhaeuser Company: PIs - Dr. Zakiya Leggett, Dr. Eric Sucre TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
As this report is for Year 1 of a five year project, the majority of resources and effort have been invested in establishing the experiment and measurement systems (planting, treatments, instrumentation for micro-meteorology, sap-flow, hydrology, soil respiration, soil C and N cycling, plant biomass, etc.). Results (long-term data sets, statistical analyses, data interpretation and inferences are limited at this time. Never-the-less, our team has been active in communicating project activities at a variety of venues to foster collaboration, leverage resources and inform constituents (public, decision makers and regulators, scientific community, forest products industry, etc.) of this important work. Presentations: *Albaugh JM, King JS, Sucre EB, Leggett ZH. 2011. Switchgrass establishment success and photosynthetic performance in an intercropped forestry system on the Lower Coastal Plain of North Carolina, presented at the 12th North American Agroforestry Conference, Athens, GA, June 4-9, 2011. *Albaugh JM, Domec J-C, King JS, Maier CA, Sucre EB, Leggett ZH. 2011. Water relations and water use in a pine-switchgrass intercropping stand grown for biofuel production on the Lower Coastal Plain of North Carolina, field presentation at Lenoir 1 Intercropping Sustainability Study Research Meeting, Nov 17-18, 2011. *King JS, Domec J-C, Albaugh J, Stape J, Leggett Z, Sucre E, Johnsen K, Maier C, Seiler J, Fox T, Strahm B. Pine-Switchgrass Intercropping for Sustainable Timber and Biofuels Production, poster presented at NIFA/AFRI Project Director's Meeting on Sustainable Bioenergy and Bioproducts, October 24-26, 2011, VA. *Leggett, Z. Sustainable biomass production research program. Oral Presentation at the EPA Biofuels and the Environmant Workshop. November 2011. Alexandria, VA. *Leggett, Z. H., J. Nettles, E. Sucre, D. Miller, and J. Homyack. Evaluating the effects of biomass production in managed pine forests on water quality and quantity, soil productivity, and wildlife. Oral Presentation at the 2011 Ecological Society of America Meeting. August 2011. Austin, TX. *Minick, K. J., B. D. Strahm, T. R. Fox, E. B. Sucre, Z. H. Leggett and J. L. Zerpa. Temporal Patterns of Soil Nutrient Availability In Southern Loblolly Pine Forests Intercropped with Switchgrass. Oral Presentation at the 2011 Soil Science Society of America Meeting. October 2011. San Antonio, TX. *Sucre, E.B. Weyerhaeuser & Catchlight Energy Bioenergy/Biofuel Opportunities for Loblolly Pine Plantation Forestry: A Multi-Faceted Approach. Oral Presentation at the South Carolina Society of American Foresters Meeting. June 2011. Columbia, SC. *Sucre, E.B. and Z.H. Leggett. The Impact of Annual Harvesting of Switchgrass Intercropped In Loblolly Pine Plantations On Soil Compaction and Long-Term Soil Productivity. Poster Presentation at the 2011 Soil Science Society of America Meeting. October 2011. San Antonio, TX. *Sucre, E.B. and Z.H. Leggett. Effects of pine-switchgrass system on tree productivity, nutrients and carbon cycling. Oral Presentation at the 2011 Society of American Foresters National Convention. October 2011. Honolulu, HI.

Publications

• No publications reported this period