Source: UNIVERSITY OF NEW HAMPSHIRE submitted to
INVASIVE PLANT IMPACTS ON NEW HAMPSHIRE FOREST ECOSYSTEM SERVICES.
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
1010675
Grant No.
(N/A)
Project No.
NH00088-M
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Oct 1, 2016
Project End Date
Sep 30, 2019
Grant Year
(N/A)
Project Director
Gunn, JO, .
Recipient Organization
UNIVERSITY OF NEW HAMPSHIRE
(N/A)
DURHAM,NH 03824
Performing Department
Natural Resources and the Environment
Non Technical Summary
Invasive non-native plants lead to significant financial and ecological damage to forest systems and are likely to increase in scale and severity under a warming New Hampshire climate. Ecosystem services such as timber product outputs and carbon sequestration can be influenced by non-native plant invasions and present challenges to forest managers. Outcomes of this project will provide a statewide assessment of the status and distribution of invasive plant species throughout New Hampshire that pose the greatest threat to forest systems. The project will also provide an evaluation and quantification of the stand- and landscape-level factors that increase forest resistance to colonization by invasive plants. Based on these factors, management best practice guidelines will be produced to help foresters and landowners minimize the risk of invasive plant species invasion into native forest stands.
Animal Health Component
0%
Research Effort Categories
Basic
30%
Applied
50%
Developmental
20%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
12306131070100%
Goals / Objectives
This goal of this project is toassess the status and distribution of invasive plants throughout New Hampshire which pose the greatest threat to forest systems, and toquantify their potential impacts to forest ecosystem services of late-successional and old growth forest communities. The practical outcome will be to provide guidance, now lacking, to forest managers on mitigating invasive threats to woodlands under climate change.The following objectives arealigned with the "forest ecosystem services" emerging knowledge area identified in the 2007 McIntire-Stennis Strategic Plan and fits within mandates 1, 2, and 5 of the McIntire-Stennis Program.Define the status of invasive plant species populations in New Hampshire and what threat they pose to forest ecosystems (with an emphasis on shade tolerant invasive plant species).Evaluate stand- and landscape-level thresholds for the imperviousness of forest communities to plant invasion and define factors that increase forest resistance to colonization by invasive plants.Quantify the potential impacts to forest ecosystem services of invasive plant incursion into late-successional and old-growth forest communities throughout New Hampshire.
Project Methods
Phase 1. Status and distribution of invasive plant species throughout New Hampshire that pose the greatest threat to forest systems.The initial phase of the project will be used to set the context for the field-based work of Phases 2 and 3. I will conduct a statewide status assessment invasive plant species using available data from US Forest Service Inventory and Assessment (FIA) Phase 3 (P3) Plots where forest health data are collected (Schulz and Gray 2013). Since P3 plots will be relatively infrequent throughout New Hampshire, these data will need to be supplemented by point location data from citizen science sources such as the Invasive Plant Atlas of New England (IPANE) (Bois et al. 2011) and other known data vegetation data. Where possible, FIA plots that have been remeasured (typically a 5-year interval) will be evaluated for changes in invasive plant communities. IPANE data, including species occurrence and abundance, are collected by trained volunteers using standardized protocols with quality control measures in place (Bois et al. 2011; Allen et al. 2013). IPANE plot locations are likely biased closer to population centers (Allen et al. 2013), therefore FIA data may provide the best assessment in these areas. I will evaluate the ability of the statewide FIA assessment to predict the presence of invasive species by using the more localized datasets such as IPANE to test the species distributions predicted by an extrapolation of FIA data (e.g., at a 30m pixel scale). The degree of concordance between the IPANE species occurrences and FIA occurrences within those pixels can be evaluated using a chi-square analysis.FIA data can also be used to assess relative age of forest communities, canopy cover, forest harvest activity, and other forest health factors that may make stands more susceptible to invasion. This information will be used to plan my Phase 2 and 3 field studies.Phase 2. Evaluate stand- and landscape-level factors that increase forest resistance to colonization by invasive plants.Field sites will be located within three regions of New Hampshire (north, central, south) to evaluate latitudinal and land use/land changegradients of forest invasion. Phase 1 results will inform the overall study design for a field campaign in terms of location, number of plots, and geographic emphasis (as dictated by observed north - south variability). My approach will follow a two-tiered approach to evaluateboth local and landscape factors of invasive plant spread.Stand Level FactorsI plan to evaluate a forest management continuum (even-aged management, uneven-aged management, unmanaged LSOG forest) to characterize stand-level factors that lead to invasion susceptibility by shade tolerant invasive plant species. Vegetation sampling methodology will be designed to allow comparison with statewide datasuch as the FIA inventory.Landscape FactorsExisting spatial datasets will be used to study the role of landscape context and landscape structure in facilitating shade tolerant invasive plant species infiltration into managed and unmanaged forest stands (i.e., "landscape resistance"). LANDFIRE existing vegetation type (30m resolution), National Agriculture Imagery Program (NAIP) land cover data (1m resolution, 4 band), and a range of land use change datasets and high resolution imagery available through the Google Earth Engine© can be utilized to characterize the relationship between the forested and non-forest landscape. High resolution data such as NAIP imagery will be useful for identifying hard edges between cover types (e.g., forest and roads). LANDFIRE, though at a coarser scale, provides insight on variables important for invasives species such as existing vegetation height and data on natural disturbances such as vegetation management (harvesting), insects, and disease. Landscape metrics including the characterization of forest edges, forest patch size, non-forest matrix will be developed using existing tools such as FRAGSTATS (for raster spatial data) or PolyFrag (for vector spatial data) (MacLean and Congalton 2015). Additionally, Ducey et al. (2016) recently have summarized land use change patterns throughout New England. These data will be useful for evaluating landscape context. Road, recreational trails, impervious surface data, and riparian networks (available from that GRANIT NH geospatial data repository) are also significant features required for a landscape analysis. Historical land cover changes will be analyzed where possible to understand the temporal component of invasion and colony establishment.Phase 3. Quantify the potential impacts to forest ecosystem services of invasive plant incursion into late-successional and old-growth forest communities throughout New Hampshire.My investigation of the ecosystem service impacts of invasive species colonization of late-successional and old-growth forests will focus on the provisioning service of timber products, the regulating services of carbon sequestration and water purification (MA 2005). Research on timber products and carbon sequestration generally will be conducted on upland forest sites, while the investigation of water purification impacts will focus on the riparian zone of first through fourth order streams.Timber Production and Carbon StocksTimber production and carbon storage dynamics at the study sites established in Phase 2 will be evaluated using the Northeast Variant of the US Forest Service Forest Vegetation Simulator - Fire and Fuels Extension (FVS-FFE). The observed (from Phase 2) or theoretical impacts of invasive species on commercial tree species regeneration and productivity can be simulated by adjusting model parameters to look at the potential long-term influence on timber product outputs and carbon storage in standing carbon forest carbon stocks and in forest products. Simulation scenarios likely will include: (1) managed and unmanaged business-as-usual growth and regeneration unhindered by invasive species; and (2) managed and unmanaged stands with invasive species impact included. Other modeling tools, such as LANDIS-II, will be evaluated for use in achieving analytical objectives, particularly to scale up to larger landscapes. LANDIS-II can be used to simulate forest succession, disturbance, climate change, and seed dispersal across large landscapes (Scheller et al. 2007).Water PurificationPotential impacts of invasive plant colonization and establishment on water quality will be evaluated indirectly by quantifying forest structural differences between natural and invaded stands. Direct impacts are difficult to quantify and expensive at different scales, but will be inferred based on other research in the region (e.g., at Hubbard Brook Experimental Forest). Forest structure, such as canopy closure and the amount of bare ground will influence the ability of the riparian zone to act as a buffer to capture the overland flow of sediment and other pollutants into water bodies. These structural features will be used as proxies to understand potential impacts of invasive plants on water quality. Particular attention will be paid to measures of ground cover and disturbance which have the most direct measurable impact on water quality.Riparian study sites will be determined based on the Phase 1 statewide mapping exercise. Ideally, paired invaded/natural sites will be established for comparison. In contrast to Phase 2, narrow rectangular transects/plots will be used to evaluate changes in vegetation communities relative to the stream edge. For stream orders 3 and 4, 2m X 100m plots will be established perpendicular to the stream edge to capture the entire riparian zone, which in New Hampshire forested landscapes will typically be less than 100m wide (depending upon topography;). For 1st and 2nd order streams, the riparian zone will be smaller, so 2m X 50m transects will likely capture the typical width.

Progress 10/01/16 to 09/30/19

Outputs
Target Audience:The target audience for the outcomes reached by this work are professional foresters and natural resource managers who work to manage forests and wish to mitigate the risks and impacts of invasive species incursion into forests. A secondary audience is forest landowners and loggers who are often decision-makers that directly influence vegetation management. UNH Cooperative Extension County foresters were also reached by this work. Finally, the scientific community involved with the study of invasive species and ecosystem services is a target audience through academic meetings and peer-reviewed journal publications. May 22, 2019. Chad Hammer (graduate student presenter). The Impacts of Terrestrial Invasive Plants on Streams and Natural and Restored Riparian Forests in Northern New England (MS thesis). UNH Cooperative Extension Forest Stewardship Area of Expertise Meeting. Sullivan County, Unity, NH (15 people, UNHCE extension forestry staff, statewide forestry leader, NR Team leader) April 9, 2019. Chad Hammer (graduate student presenter) and John Gunn. Restoring Riparian Buffers when Invasive Species are Present. Watersheds United Vermont Spring Meeting, Waterbury, VT. (25 people, natural resource managers, conservation practitioners, state and federal agency staff) March 28, 2019. Chad Hammer (graduate student presenter) and John Gunn. The impacts of terrestrial invasive plants on natural and restored riparian forests in northern New England. Flash Talk. New England Society of American Foresters Winter Meeting, Burlington, VT. (50 professional foresters, natural resource managers, researchers, and conservation practitioners) December 10, 2018. John S. Gunn, Mark J. Ducey, Thomas Buchholz, and Ethan P. Belair. Poster Presentation. Silvicultural Strategies for Mitigating Northern Forest Carbon Loss Due to Spruce Budworm (Choristoneura fumiferana) American Geophysical Union (AGU) Fall Meeting, Washington, DC. (100 people, ecologists and natural resource scientists) Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Opportunities for undergraduate and graduate students were provided throughout the three years of the project. Mentoring was provided to two summer undergraduate research assistants, one MS graduate student as a primary supervisor (successfully completed degree within 2 years), one MS graduate student hourly worker, and two PhD student research assistants. Graduate student Chad Hammer completed his degree in two years under my supervision and was awarded the "Graduate Student of the Year" award by the Granite State Society of American Foresters in February 2019. Chad presented the results of his research at a regional professional forestry meeting, to UNH Cooperative Extension staff and county foresters, and to a regional watershed protection meeting. How have the results been disseminated to communities of interest?The findings of this research have been and will continue to be directly presented to policy makers and land managers (state, federal, and non-profit) at regional watershed, invasive plant, and forestry conferences and working group meetings. Examples of these meetings include the presentation of this research by graduate student Chad Hammer at the 2019 Watersheds United Vermont spring meeting to ~30 people including conservation practitioners, land trust staff, and representatives of state and federal agencies. The results have also been presented at regional professional forestry meetings (New England Society of American Foresters in March 2019), and an international academic meeting (American Geophysical Union Winter Meeting 2018, Washington, DC). Regular presentations of ongoing research and final results were presented to UNH county extension foresters. One general public presentation was given to the local retirees' association in Durham, New Hampshire. Point location data of invasive plants will be provided to stakeholders and interested agencies including: Trout Unlimited, Upper Connecticut Cooperative Invasive Species Management Area, and the White Mountain National Forest. Additionally, plot locations and vegetation surveys may serve as valuable baseline data for long-term monitoring of these sites, especially useful to the White River Partnership (project collaborator) to gauge long-term success of their restoration projects and also future research projects at the University of New Hampshire. Finally, the interactive invasive plant and forest disturbance risk map has been made publicly available online. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Invasive non-native plants lead to significant financial and ecological damage to forest systems and are likely to increase in scale and severity under a warming New Hampshire climate. Ecosystem services such as timber product outputs, water quality protection, and carbon sequestration can be influenced by non-native plant invasions and present challenges to forest managers. Outcomes of this project include a statewide assessment of the status and distribution of invasive plant species throughout New Hampshire and detailed insight on specific impacts of invasive plants to ecosystem services such as water quality protection and carbon sequestration. The project also represents one of the first studies in the northeast to show that planting native tree species for post-disturbance forest restoration can be an effective way to reduce invasive plant establishment. Objective 1. Define the status of invasive plant species populations in New Hampshire and what threat they pose to forest ecosystems (with an emphasis on shade-tolerant invasive plant species). Invasive plants that threaten the functioning of natural forests are rapidly increasing in diversity, abundance, and distribution across the state of New Hampshire. Foresters and landowners need to understand where this risk is greatest and which species pose the greatest threat to forest resources. With the assistance of graduate student Erica Holm (M.S. candidate in the Department of Natural Resources and the Environment), I developed a statewide web-based "risk" map. The interactive map incorporates existing known locations of shade-tolerant invasive plant species that brings together multiple forest disturbance factors to identify the regions where invasive plants should be of greatest concern to foresters and natural resource managers. The map is also the basis for elements of Objective 2 below. Objective 2. Evaluate stand- and landscape-level thresholds for the imperviousness of forest communities to plant invasion and define factors that increase forest resistance to colonization by invasive plants. To evaluate the impacts of invasive plants on old forest stands in New Hampshire, I revisited stands first surveyed by UNH graduate student Lee Carbonneau in 1984-85 for her forestry program MS thesis. Project planning was carried out during the spring semester (2018) with the assistance of UNH undergraduate student Monica Newton. Monica graduated from UNH in May 2018 (Wildlife and Conservation Biology) and conducted fieldwork for this project during the summer of 2018. Twenty-four vegetation survey plots were established at five different old-growth forest sites in New Hampshire. Data were collected on forest structural characteristics (e.g., diameter, species, height, stem density). Invasive plant species were identified and mapped when found near the plots. Graduate student Erica Holm analyzed forest structure data to quantify species composition, carbon stocks, and diameter distribution of all age classes. For all study sites, invasive plant species have not yet infiltrated the old forest stands. Basal area and carbon stocks in the old forest stands are 4-5 times that expected in average stands in the region. These findings highlight the importance of old forests as carbon sinks. However, up to 80% of the carbon volume at many of the sites are found in eastern hemlock and white ash trees - both tree species are currently at risk in the study region from invasive pest species. If the invasive pests arrive, carbon stocks could be compromised, and nearby invasive plant species will have fewer barriers to movement as a result of the disturbance creating new growing space. The web-based risk map described above in Objective 1 incorporates the risk to forest carbon stocks in New Hampshire by overlaying carbon density (MT/ha) on the eight risk factors assessed statewide. The interactive map allows the user to adjust the inclusion or exclusion of each risk factor to tailor an assessment based on more localized concerns. The map shows a clear pattern of existing high risk of invasive plant species in the SE portion of the state that coincides with low existing carbon stocks. Statistical clusters of risk vs. carbon relationships show that a swath of land from Carroll, Belknap, Hillsborough and Merrimack counties in the center of the state have relatively high forest carbon stocks that are at risk from disturbances related to invasive plant species, roads, and forest fragmentation. Understanding these relationships can help foresters and natural resource managers to determine linkages between invasive plant species occurrences and broader patterns in the landscape, such as land development, roads, and agriculture. Objective 3. Quantify the potential impacts to forest ecosystem services of invasive plant incursion into late-successional and old-growth forest communities throughout New Hampshire. Non-native invasive species are a major cause of ecosystem degradation and impairment of ecosystem service benefits in the United States. Forested riparian areas are often also in older age classes and provide many ecosystem service benefits to humans and are vital to streams and rivers ecosystems. Riparian areas are at high risk for invasion because they are among the most human-disturbed ecosystems in the world. In this study, we quantified the impacts of terrestrial invasive plant invasions by species like Japanese knotweed (Fallopia japonica) on riparian forest structure, stream physical habitat, soil structure, and soil behavior. In addition, we assessed the effects of restoring native trees to disturbed riparian sites and their ability to resist invasive plants. We found that invaded sites had greater stems per hectare (specifically 2-5m tall) but were often associated with reduced basal area. Invaded plots consistently had greater canopy closure upland from the stream (5m from the stream edge) but provided less shade at the stream bank with larger open canopy angles, therefore increasing the amount of solar radiation entering the stream channel. Native tree sapling densities were often reduced in invaded sites when compared to non-invaded sites. Significantly less organic material was available at invaded sites, with less coarse woody debris and reduced litter and duff layers on the forest floor. When comparing planted vs. non-planted riparian sites, we found that non-planted sites had 43% more stems per hectare and three times the amount of invasive plants. The results of this study may assist conservation efforts of riparian forests to further understand the distribution of invasive plants, how to minimize the risk of invasion, and how to mitigate the effects on ecosystem services and functioning. Overall, this research can assist land managers and conservation efforts of headwater streams and riparian forests in New England to further understand the impacts and distribution of invasive plants. Furthermore, this study may assist conservation efforts to minimize the risk of invasion and mitigate the effects on ecosystem services and functioning. A follow-up study on invasive plant movement and impacts to trout habitat is being planned for 2020. The study will build on aerial imagery survey methods that were developed with the assistance of graduate students Ben Fraser and Heather Grybas as part of this AES project. The students are pioneering the use of drones as tools to delineate vegetation such as invasive plant species. This work is critical to be able to assess the extent of current invasive populations and allow natural resource managers to control spread and mitigate impacts.

Publications

  • Type: Theses/Dissertations Status: Published Year Published: 2019 Citation: Hammer, C.F. 2019. The Impacts of Terrestrial Invasive Plants on Streams and Natural and Restored Riparian Forests in Northern New England. M.S. Thesis. University of New Hampshire, Department of Natural Resources and the Environment. 95pp.
  • Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Gunn, J.S., M. J. Ducey, T. Buchholz, and E. Belair. In Review. Forest Carbon Resilience of Eastern Spruce Budworm (Choristoneura fumiferana) Salvage Harvesting in the Northeastern United States. Frontiers in Forests and Global Change.
  • Type: Journal Articles Status: Under Review Year Published: 2019 Citation: Hammer, C.F., and J.S. Gunn. In Review. Impacts of Terrestrial Invasive Plants on Streams and Riparian Forests in Northern New England. Biological Invasions.
  • Type: Websites Status: Published Year Published: 2019 Citation: Gunn, J.S., and E. Holm. New Hampshire Forest Disturbance Risk Maps. Tableau Public Story with interactive data visualizations of forest disturbance risk factors, including invasive plant species and the potential impact to forest carbon stocks. https://public.tableau.com/profile/john.gunn#!/vizhome/NewHampshireForestDisturbanceRiskMaps/NewHampshireForestDisturbanceRisk Last accessed 11/21/2019.


Progress 10/01/17 to 09/30/18

Outputs
Target Audience:The target audience for the outcomes of reached by this work are professional foresters and natural resource managers who work to manage forests and wish to mitigate the risks of invasive species incursion into forests. A secondary audience is forest landowners and loggers who are often decision makers that directly influence vegetation management. UNH Cooperative Extension County foresters were also reached by this work. Finally, the scientific community involved with the study of invasive species and ecosystem services will be a target audience through peer-reviewed journal publications. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project has provided training and professional develop opportunities to a graduate student through mentoringondesigning a research project, planning and organizing field research activities, andmanaging a field crew under challenging work conditions (rain, heat, bugs, terrain). Specific training has been undertaken through graduate-level course work focused on forestry and related content. The graduate student has also had opportunities to develop professionally through public presentation of his research and communicating through social media and blog formats that have become essential tools for science communication. Two undergraduate students were also trained in field research skills. How have the results been disseminated to communities of interest?In addition to the peer-reviewed scientific publication listed, the results of completed research, and updates on ongoing research have been disseminated through public presentations and blog posts available on John Gunn's UNH web site. These talks and blogs are listed below: John Gunn.April 27, 2018. Invited Talk.Forest degradation in northern New England. Mud Season Breakfast. Whitefield, NH. 150 foresters and natural resource professionals Chad Hammer. February 22, 2018. Oral Presentation. Assessing the Invasion Patterns and Impacts of Terrestrial Invasive Plants in New England Riparian Forests. At the Invasive Plants in the Granite State Forum. Concord, NH. 35 natural resource professionals in attendance Chad Hammer. Blog Post. Research project on the invasion patterns and impacts of invasive plants in New England riparian forests is about to kick off! April 30, 2018. https://mypages.unh.edu/gunnlab/blog/research-project-invasion-patterns-and-impacts-invasive-plants-new-england-riparian Chad Hammer. Blog Post. Invasion Dynamics, Aldo Leopold, and the Penalties of an Ecological Education. March 27, 2018. https://mypages.unh.edu/gunnlab/blog/invasion-dynamics-aldo-leopold-and-penalties-ecological-education Lori Wright (NHAES Communications Director). Summertime Means Field Work for UNH Student Researchers. Online Video. https://youtu.be/tkTixVHOxbQ What do you plan to do during the next reporting period to accomplish the goals?1. Define thestatus of invasive plant species populationsin New Hampshire and what threat they pose to forest ecosystems (with an emphasis on shade tolerant invasive plant species). During the spring of 2019 additional work with the GIS database assembled duringyear one of the project, will be conducted to infer the distribution and density of focal invasive species (particularly shade tolerant species that pose the greatest risk to forest resources). The result is intended to be a web-based risk map accessible to foresters and forest landowners to evaluate threats to woodlands. 3. Quantify the potential impacts to forest ecosystem services of invasive plant incursion into late-successional and old-growth forest communities throughout New Hampshire. Garland Brook is the town water supply for Lancaster, NH, so understanding the potential impacts of invasive plant communities on water quality is of particular importance in this watershed. Forfieldwork conducted in Garland Brook watershed in the summer of 2018;analysiswill be conducted in October-December, 2018 to evaluate the impacts of invasive plant communities on forest structure, carbon storage, and water quality.

Impacts
What was accomplished under these goals? Invasive plants that threaten the functioning of natural forests are rapidly increasing in diversity, abundance, and distribution across the state of New Hampshire. Foresters and landowners need to understand where this risk is greatest and which species pose the greatest threat to forest resources. 2. Evaluate stand- and landscape-level thresholds for the imperviousness of forest communities to plant invasion and define factors that increase forest resistance to colonization by invasive plants. Part of understanding the threat that invasive plant species pose to forest communities is to understand the factors make forests more or less resistant to invasion. Foresters need to understand these factors as they make a decision to implement silvicultural practices to manage the forest resource. There are two components to this work - 1) using existing data; 2) collect new field data. To evaluate the impacts of invasive plants on old forest stands in New Hampshire, I revisited stands first surveyed by UNH graduate student Lee Carbonneau in 1984-85 for her forestry program MS thesis. Project planning was carried out during the spring semester (2018) with the assistance of UNH undergraduate student Monica Newton. Monica graduated from UNH in May 2018 (Wildlife and Conservation Biology) and conducted fieldwork for this project during the summer of 2018. Twenty-four vegetation survey plots were established at five different old growth forest sites in New Hampshire. Data were collected on forest structural characteristics (e.g., diameter, species, height, stem density). Invasive plant species were identified and mapped when found near the plots. These data will be added to existing regional data assembled during Year 1 of the project. In the coming months, this forest structure data will be related to invasive species location data and continuous forest inventory data collected in the summer of 2017 at Kingman Farm by University of New Hampshire Woodlands staff. Understanding the relationship between forest structure, age, and the presence or absence of invasive plant species is important to assess the imperviousness of forest communities to plant invasion. Landscape-scale data (e.g., roads, development, land cover) assembled during the winter of 2018/2019 will also be used to determine linkages between invasive plant species occurrences and broader patterns in the landscape, such as land development, roads, and agriculture. 3. Quantify the potential impacts to forest ecosystem services of invasive plant incursion into late-successional and old-growth forest communities throughout New Hampshire. Invasive plants can negatively impact the flow of ecosystem services such as carbon sequestration and water quality protection that are typically provided by natural forests. Understanding these impacts can help make decisions about where to invest limited natural resource cost-share funds and help conservation planners evaluate investments to protect old forests from invasive plants through activities like eradication and control. During October - December 2017, M.S. Student Chad Hammer began planning a research project to study how riparian forests (forests along rivers and streams) may act as a movement corridor for invasive plants to move into the interior forest (also related to Objective 2) and what impacts invasion has on forest ecosystem services. Fieldwork was conducted at two sites during the summer of 2018: 1) Garland Brook, Lancaster, NH; 2) White River, VT (several towns). Garland Brook is the town water supply for Lancaster, NH, so understanding the potential impacts of invasive plant communities on water quality is of particular importance in this watershed. The length of the stream (~35km) was surveyed for invasive plant species from July to August 2018. We were able to complete 23 systematic vegetation surveys along the stream (every 800m) and then 15 additional surveys where invasive species were present. The invasive plots were established along the stream prioritizing the following: 1) Size of invasive community, 2) dispersed evenly throughout the stream in an attempt to capture the same gradient as the systematic plots (rural, agricultural, forested, mountainous). More than 300 invasive species occurrences were mapped (Japanese knotweed, glossy buckthorn, Morrow's honeysuckle).five sites along the White River in north-central Vermont. The forests at these sites have been completely removed by the flooding of Tropical Storm Irene in 2011 and were replanted by a local land trust attempting to restore the riparian vegetation critical for protecting water quality. However, many sites have since been invaded by non-native plant species such as Japanese knotweed. In May-June 2018 we surveyed 41 plots to assess the factors related to the presence or absence of invasive plants at the planted sites. Understanding the factors that promote "resistance" to invasives will help the land trust be more successful and efficient in future restoration efforts.

Publications

  • Type: Journal Articles Status: Published Year Published: 2019 Citation: Gunn, J.S., M.J. Ducey, and E. Belair. 2019. Evaluating forest degradation in a North American Temperate Forest. Forest Ecology and Management 432: 415-426.


Progress 10/01/16 to 09/30/17

Outputs
Target Audience:During the project period, I met collectively with the 9 professional foresters who serve as New Hampshires Cooperative Extension Foresters. At this meeting, I discussed my proposed research to gain insight from their experiences and to hear their forest management concerns related to invasive plant species. Two follow-up meetings were held with one of these extension foresters who works in the study area where field work will be conducted in summer 2018. Two natural resource managers were also involved with these meetings (NH Fish and Game, Trout Unlimited). OnSeptember 28, 2017, I gave a presentation entitled "Invasive Plants in the Granite State" to the Active Retirement Association of Durham, NH for their Science Thursday series. There were 15 local landowner attendees. The scientific community involved with the study of invasive species and ecosystem services will be reached through the publication of a book chapter on invasive pests and pathogens and their impacts on old-growth forests that will be forthcoming in July 2018. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?A Masters of Science student (in the Forestry program) began working on the project in August 2017. On September 28, 2017 a presentation on "Invasive Plants in the Granite State" was made to 15 members of the Active Retirement Association of Durham, NH. How have the results been disseminated to communities of interest?The project period was primarily a data collection and initial analysis phase for the project. What do you plan to do during the next reporting period to accomplish the goals?1. Define the status of invasive plant species populations in New Hampshire and what threat they pose to forest ecosystems (with an emphasis on shade tolerant invasive plant species). During the winter of 2018 additional work the GIS database will be conducted to infer the distribution and density of focal invasive species (particularly shade tolerant species that pose the greatest risk to forest resources). The result will be a web-based risk map accessible to foresters and forest landowners to evaluate threats to woodlands. 2. Evaluate stand- and landscape-level thresholds for the imperviousness of forest communities to plant invasion and define factors that increase forest resistance to colonization by invasive plants. The second component of the work around this objective will involve field work during the summer of 2018 to investigate imperviousness of forest communities directly in late-successional and old-growth forest stands throughout New Hampshire. Additional work will be conducted at Kingman Farm at known locations of invasive plant communities (determined during the 2017 inventory) to quantify in more detail the forest structural attributes of invaded and non-invaded sites. Landscape-scale data (e.g., roads, development, land cover) will also be used to determine therelationship to invasive species presence. 3. Quantify the potential impacts to forest ecosystem services of invasive plant incursion into late-successional and old-growth forest communities throughout New Hampshire. The primary work for this objective will take place during years 2 and 3 of the project. The M.S. student taken on in August 2017 will conduct field work in the Upper Connecticut River watershed during the summer of 2108. Additional field work will also be conducted at old forest sites throughout New Hampshire and on lands owned by the Blue Hills Foundation in Stratham, New Hampshire, Kingman Farm in Madbury, New Hampshire.

Impacts
What was accomplished under these goals? Invasive non-native plants lead to significant financial and ecological damage to forest systems and arelikely to increase in scale and severity under a warming New Hampshire climate. Ecosystem services such as timber product outputs and carbon sequestration can be influenced by non-native plant invasions and present challenges to forest managers. Outcomes of this project will provide a statewide assessment of the status and distribution of invasive plant species throughout New Hampshire that pose the greatest threat to forest systems. The project will also provide an evaluation and quantification of the stand- and landscape-level factors that increase forest resistance to colonization by invasive plants. Based on these factors, management best practice guidelines will be produced to help foresters and landowners minimize the risk of invasive plant species invasion into native forest stands 1. Define the status of invasive plant species populations in New Hampshire and what threat they pose to forest ecosystems (with an emphasis on shade tolerant invasive plant species). Invasive plants that threaten the functioning of natural forests are rapidly increasing in diversity, abundance, and distribution across the state of New Hampshire. Foresters and landowners need to understand where this risk is greatest and which species pose the greatest threat to forest resources. During this project period, I have accumulated existing data to complete a statewide assessment of the status of invasive plant species populations. Primary data collected include a variety of local, regional, and statewide datasets from the following sources: US Forest Service Forest Inventory and Assessment (FIA) forest health plot data (regional) Upper Connecticut River Cooperative Invasive Species Management Area point location data (NH, VT) Invasive Plant Atlas of New England (IPANE) point location data (statewide NH) These data have been assembled in a Geographic Information System database. One outcome of developing this database is to identify potential study site locations for field-based research planned for summer and fall of 2018 (see Objectives 2 and 3. Comprehensive statewide data are lacking, but good assessment data has been acquired for Upper CT River watershed points to this region in particular where field work will be supported by this broader dataset (described below). 2. Evaluate stand- and landscape-level thresholds for the imperviousness of forest communities to plant invasion and define factors that increase forest resistance to colonization by invasive plants. Part of understanding the threat that invasive plant species pose to forest communities is to understand the factors make forests more or less resistant to invasion. Foresters need to understand these factors as they make decision to implement silvicultural practices to manage the forest resource. There are two components to this work: 1) analyze existing data; 2) collect new field data. The first builds on the statewide status assessment described in Objective 1 and uses the same FIA data to quantify forest structure and begin to relate structural variables (such as stand density, stand age, mean diameter) to invasive species presence. Along with UNH colleague Dr. Mark Ducey, I have completed an assessment of FIA data to reveal that significant acreage in New Hampshire, Vermont, and Maine are stocked at a relatively low density, which may put these acres at risk of invasion (based on patterns documented in existing literature). This work has led to a manuscript in preparation with Dr. Ducey for submission to the journal Forest Ecology and Management. Investigations in the next period will relate this forest structure data to invasive species location data (using FIA data) and continuous forest inventory data collected in summer of 2017 at Kingman Farm by University of New Hampshire Woodlands staff. The second component of the work will be completed during the second project year. During the project period, I also conducted a pilot study to evaluate the potential for unmanned aerial systems (aka drones) to efficiently detect invasive plant locations within interior forests and along power line right of way corridors. Two drone flights using high resolution color and multi-spectral imagery were conducted - one a Kingman Farm (UNH Woodlands) and one along a power line corridor in coordination with UNH Cooperative Extension Professor Dr. Matt Tarr and his M.S. student. Results were mixed, but further analysis is required with the data that is now available from the 2017 inventory at Kingman Farm. The power line corridor site chosen for a pilot flight ended up having a lower density of invasive plant species than believed from an initial ground assessment and proved difficult to identify individual stems of invasive species. However, high resolution color photography obtained in the early spring at Kingman Farm has shown strong promise to identify locations of species like Japanese barberry that leaf out early and have a distinct color from native species. This will be investigated further using the Kingman Farm data that was processed during the fall of 2017. Also during the project period, I hired a graduate research assistant to conduct a project that supports both Objectives 2 and 3 by looking at how riparian forests (forests along rivers and streams) may act as a movement corridor for invasive plants to move into interior forest (Objective 2) and what impacts invasion has on forest ecosystem services (Objective 2). The M.S. student began at UNH in August 2017. 3. Quantify the potential impacts to forest ecosystem services of invasive plant incursion into late-successional and old-growth forest communities throughout New Hampshire. Invasive plants can negatively impact the flow of ecosystem services such as carbon sequestration and water quality protection that are typical provided by natural forests. Understanding these impacts can help make decisions about where to invest limited natural resource cost-share funds and help conservation planners evaluate investments to protect old forests from invasive plants through activities like eradication and control. The primary work for this objective will take place during years 2 and 3 of the project. One major outcome from year 1 of the project is the preparation of a detailed literature review on the threats that invasive pests and pathogens pose to old forests in the eastern United States. The result is a book chapter that has been accepted for publication in Ecology and Recovery of Eastern Old-Growth Forests which is anticipated to be published in July 2018. The chapter is co-authored by Dr. David Orwig of the Harvard Forest.

Publications

  • Type: Book Chapters Status: Awaiting Publication Year Published: 2018 Citation: Gunn, John S., and D. Orwig. 2018. Old-growth forests under threat: changing dynamics due to invasive plants, pests and pathogens. Chapter 12 in: Ecology and Recovery of Eastern Old-Growth Forests. William Keeton and Andrew Barton (Editors). Island Press. 288pp.