OPTIMIZING SUSTAINABLE MANAGEMENT OF MIDWESTERN FORESTS BY IDENTIFYING CONTEXT-SPECIFIC LIMITS TO TREE AND PLANT RECRUITMENT

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: NEW
• Funding Source: AFRI COMPETITIVE GRANT
• Reporting Frequency: Annual
• Accession No.: 1024818
• Grant No.: 2021-67019-33427
• Project No.: WISW-2020-05111
• Proposal No.: 2020-05111
• Program Code: A1451
• Project Start Date: May 1, 2021
• Project End Date: Apr 30, 2025
• Grant Year: 2021

Project Director
Orrock, J. L.

Recipient Organization
UNIV OF WISCONSIN
21 N PARK ST STE 6401
MADISON,WI 53715-1218

Performing Department
Integrative Biology

Non Technical Summary
Forests in the United States represent a vital national and natural resource. By providing sustainable timber production, these forests represents one of the major consistent revenue sources in the rural U.S., as well as provide essential ecosystem services, sequestering atmospheric carbon, harboring diverse understory plant communities, supporting agricultural services (e.g., pollination and natural pest control), and bolstering regional human recreation and health. For example, carbon sequestration by trees in U.S. urban environments is valued at ~$460 million per year, and reduction of air pollutants (e.g., carbon monoxide, ozone, nitrogen dioxide) can be worth as much as $8 million per year in some U.S. cities. Sustainably managing U.S. forests, and the services they provide, depends upon overcoming two of the primary barriers to tree and plant reproduction and survival: invasive shrubs and native herbivores and granivores. Of great importance is that these two factors may amplify one another, such that invasive shrubs and native herbivores have the potential to dramatically reduce successful forest regeneration. A primary challenge is that, although we know that their effects can be devastating, we still lack a means to predict when and where the effect of exotic shrubs and native animals will be most harmful and which tree and plant species will be most affected. Until we understand the independent and interactive effects of invasive shrubs and plant-eating animals on plant and tree recruitment in different forest types, our ability to manage for sustainable U.S. forests will remain inefficient (at best) or completely ineffective (at worst).This project uses a large-scale approach to determine the relative importance of the two greatest threats to managed forest health across the range of forest contexts typical of many forests in the Midwestern U.S. Using site-level experiments, this project will determine the relative importance of invasive shrubs and mammalian herbivores on trees and plants across a range of forest types, providing a data-driven means to identify forests where sustainability is most threatened and to prioritize management efforts. In addition, the project will directly test the effectiveness of common strategies for maximizing forest sustainability (invasive plant removal and direct seeding of trees and plants), helping identify which approach is likely to be most effective in a particular forest type. Finally, this work will test the efficacy of an innovative way to maximize tree and plant regeneration by using capsaicin to deter animal granivores and herbivores. By helping identify specific forest types where the threats posed by invasive shrubs and mammalian herbivores are greatest, while simultaneously also providing science-supported mitigation actions to address those threats, this project will help provide managers and stakeholders with the tools necessary to promote the sustainability and function of 180 million acres of forest ecosystems found throughout the Midwestern U.S.

Animal Health Component

0%

Research Effort Categories

Basic

20%

Applied

80%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
122	0120	1070	70%
136	0120	1070	15%
214	0120	1070	15%

Knowledge Area
136 - Conservation of Biological Diversity; 214 - Vertebrates, Mollusks, and Other Pests Affecting Plants; 122 - Management and Control of Forest and Range Fires;

Subject Of Investigation
0120 - Land;

Field Of Science
1070 - Ecology;

Keywords

diversity

herbivores

invasive plants

management

plant recruitment

tree recruitment

Goals / Objectives
Our long-term goal is to improve our ability to promote the sustained function of managed forests, and their associated ecosystem services, by understanding the factors that generate predictable variation in tree recruitment and plant diversity in rural and urban forests. The overall objective of this proposal, which is the next step towards achieving our long-term goal, is to use large-scale distributed experiments across a gradient of forest types to quantify variation in the effects of invasive plants and plant-eating animals on managed forest ecosystems and to identify management strategies that will maximize forest sustainability. Our central hypothesis is that the importance of invasive plants and herbivores in affecting tree recruitment and understory plant diversity depends upon whether the forest occurs in a rural, agricultural, or urban environment, because these different forest contexts impose different constraints on the effects of invasive plants and herbivores. We have formulated this hypothesis based on research demonstrat-ing that the effect of invasive plants on juvenile tree survival depends upon which animals are present (e.g., Orrock et al. 2015c, Bartowitz and Orrock 2016) and that animal communities differ greatly among rural and urban forests (Faeth et al. 2005, Warren et al. 2006, Shochat et al. 2010); see Section A.3 Review of Recent Literature. Our team is particularly well suited to con-duct the proposed work because we have combined expertise in invasive plant biology and plant community ecology (Connolly et al. 2014, Orrock et al. 2015c), design and implementation of large-scale distributed experiments (Orrock et al. 2015b), and extensive experience with quantifying animal populations (Connolly and Orrock 2018b) and their effects on plant recruitment (Orrock et al. 2015c). Our ability to carry out this research is further enhanced by our collective 15 years of experience in working with forest ecology and invasive shrubs in Midwestern forests (e.g., Dutra et al. 2011, Watling et al. 2011, Orrock et al. 2015c, Bartowitz and Orrock 2016, Connolly et al. 2017a, Guiden and Orrock 2017, Guiden et al. 2018), the recent body of strong natural resource research that addresses current trends in urban and rural forestry in southern Wisconsin (e.g, Nowak et al. 2017), and by the outstanding research environments provided by our institutions (University of Wisconsin-Madison and Eastern Michigan University).Project Objectives:We plan to test our central hypothesis and, thereby, attain the objective of this proposal by pursu-ing the following specific aims:Aim 1. Determine the unique and interactive effects of invasive shrubs and herbivores on tree regeneration in multiple forest contexts. Our working hypothesis is that tree regeneration in rural forests will be primarily affected by herbivory and availability of dispersed seeds from parent trees (i.e., dispersal limitation; Clark et al. 1998), while regeneration in agricultural and urban forests will be greatly constrained by the additive effects of competition with invasive shrubs and intense reduction in tree survival due to granivory and herbivory.Aim 2. Quantify the effect of invasive shrubs and herbivores on understory plant diversity in multiple forest contexts. Our working hypothesis is that understory plant diversity will be most constrained by granivory and competition with invasive plants, rather than by herbivory (Orrock et al. 2015c), and that the effects of herbivores and invasive plants on plant diversity will both be greatest in urban forests where invasive shrubs are currently most prevalent (Huebner et al. 2012). Aim 3. Evaluate the utility of classic and novel mitigation strategies to find optimal strategies in each forest context. Our working hypothesis is that, because the primary forces limiting sustainability differ among forests contexts, forest managers will likely need to adopt unique strategies in urban compared to rural forests to obtain similar patterns of sustainable tree recruitment. For example, direct planting of trees may be most effective in forests where grani-vores are the primary agent limiting tree recruitment, while seed additions may be most effec-tive in forests where granivores are less abundant. We further explore the applicability of broadly applied management strategies by testing the efficacy of a novel, but natural, taste deterrent (i.e., capsaicin) applied to tree seeds and seedlings.This project is innovative because it uses a large-scale experimental approach to dissect the rela-tive importance of the greatest threats to managed forest health across the range of forest con-texts that managers experience. This work is expected to yield the following outcomes. First, it will produce knowledge of the primary mechanisms whereby invasive plants and mammalian herbivores affect tree regeneration and diversity in managed forests, knowledge that directly enables effectively assessing and prioritizing management strategies in different forests. Second, this work will explicitly test the efficacy of common management approaches for max-imizing regeneration and diversity across a range of forest types. Our testing structure is important for creating field-tested, science-based guidelines that provide optimal management approaches (e.g., deer exclusion, invasive shrub removal) for different forest contexts. Finally, this work is innovative: it will provide a multi-forest, multi-species test of the utility of a novel approach to increasing tree and understory plant regeneration by using capsaicin to deter animal granivores and herbivores. The proposed work will help improve the sustainability and function of forest ecosystems found throughout the Midwestern U.S. by helping identify specific forest types where the threats posed by invasive shrubs and mammalian herbivores are greatest while simultaneously also providing science-supported mitigation actions to address those threats.

Project Methods
We will establish a network of forested sites in six counties across southern Wisconsin: Grant, Iowa, Dane, Jefferson, Waukesha, and Milwaukee. We focus on a comparison of three forest types that differ in the degree to which human intervention has modified their adjacent habitat: urban forest remnants, agricultural woodlots, and rural intact forests. We will establish a network of 18 field sites across this range. Each site will include a minimum woodland lot size of 20 acres, land managers that have reviewed and approved study protocols, a canopy comprised predominantly of native Wisconsin tree species, and the presence of invasive shrubs in the woodland understory.C.1 Specific Aim #1: Determine the unique and interactive effects of invasive shrubs and herbivores on tree regeneration in multiple forest contexts.C.1.1 Experimental design: Tree regeneration response to factorial manipulation of invasive shrub cover and herbivores across multiple forest contexts.C.1.1.a. Site Layout: In summer, 2021, we will establish and maintain eighteen 50 x 50 m plots; six plots will be established each in urban forest remnants, agricultural woodlots, and rural intact forest. Each plot will be divides into four adjacent 25 x 25 m subplots. The effects of invasive shrub cover (invasive shrubs present vs. removed) and the effects of deer herbivory will be evaluated in a 2 x 2 factorial design with each subplot randomly assigned to one of the four possible subplot treatment combinations (Fig. 8). Nested within each 25 x 25 m subplot will be six 5 x 5 m plots. These 5 x 5 m plots will evaluate a 3 x 2 factorial comparison between the presence or absence of small mammal activity and a granivore feeding-deterrent seed coat treatment (see section C3, Specific Aim 3). In Fall 2021, tree seeds will be sown onto a randomly-assigned half of each 5 x 5 m plot (2.5 x 5 m area sown) at densities that emulate a good mast year and are consist with commercial post-harvest seeding rates (Bonner and Karrfalt 2008). The half of each 5 x 5 meter plot that does not receive seeds will be used to estimate natural recruitment of tree seedlings at the sub-plot level. We have used successfully this approach of combining seed additions with herbivore exclosures in forest ecosystems (Connolly et al. 2014, Turley et al. 2017), savannas (Orrock et al. 2015a), and grassland ecosystems (Orrock et al. 2009, Connolly et al. 2014).C.1.1.b. Test species selection: Test species will include a minimum of six deciduous (red oak [Quercus rubra], silver maple [Acer saccharinum], sugar maple [Acer saccharum], red maple [Acer rubrum], shagbark hickory [Carya ovata], and American elm [Ulmus americana]) and three coniferous species (red pine [Pinus resinosa], white pine [Pinus strobus], and jack pine [Pinus banksiana]) native to southern Wisconsin.C.1.1.c. Invasive Shrub Removal: Prior to shrub removal treatment, invasive shrub density will be estimated using stem density and basal area estimates for each subplot. The shrub removal treatment will be randomly assigned to two of the four subplots. Removal of shrubs will happen in late summer 2021 and will consist of mechanically removing all woody stems followed by herbicide application on remaining stumps (after Orrock et al. 2015c, Bartowitz and Orrock 2016). Plots will be monitored monthly during subsequent growing season and regrowth will be mechanically controlled. To control for non-target effects of shrub removal (e.g., inadvertent trampling of native vegetation, soil compaction), control plots will also be traversed randomly for 20 minutes during the shrub removal treatment.C.1.1.d. Herbivore Exclosures: Deer exclosures will consist of metal deer-proof fencing (e.g., Deer Busters Steel Hex Fencing) affixed in place with metal posts and secured to a height of 2.15 m around the perimeter of the plot. Metal posts, but without fencing material will be positioned around plots permitting deer entry to control for non-target effects of fencing. Construction of small mammal 5 x 5 m exclosure plots will follow guidelines similar to those we have used previously (Orrock et al. 2008, 2009, Turley et al. 2017). Briefly, for all plots, hardware cloth will be buried to a depth of 20 cm (to prevent burrowing) around the perimeter of each plot and aluminum flashing will be affixed to the top of each exclosure to prevent small mammals from scaling the exclosure. Three of the six exclosures in each 25 x 25m subplot will have holes cut into the side to permit rodent entry (i.e., a pseudoexclosure), whereas the other three exclosure will remain unaltered.C.2 Specific Aim #2: Quantify the effect of invasive shrubs and herbivores on understory plant diversity in multiple forest contextsC.2.1 Experimental design: Understory plant diversity response to factorial manipulation of invasive shrub cover and herbivores across multiple forest contextsWe rely upon the same distributed experimental design used for Specific Aim 1 (above) as the foundation for this objective. We hypothesize that small mammalian granivores will be particularly effective agents limiting understory plant diversity and that their effects will be greatest in urban forests that are also invaded by invasive shrubs (Fig. 3; Orrock et al. 2015c).C.3 Specific Aim #3: Evaluate the utility of classic and novel mitigation strategies to find optimal strategies in each forest contextC.3.1 Experimental design: Testing classic mitigation strategies and a novel chemical deterrent to vertebrate consumers across multiple forest contexts.C.3.1.a Site LayoutThe foundation of this experiment begins with the design for Specific Aim 1, because this design intentionally incorporates several classic tools for mitigation (i.e., physical removal of invasive shrubs, seed sowing to reduce propagule limitation, and exclosures to reduce effects of herbivores and granivores). The existence of these treatments makes it possible to directly compare the efficacy of capsaicin to the efficacy of these other often-used mitigation tools. To evaluate capsaicin, we add an additional level to our factorial experiment. Seeds and seedlings of focal tree species in half of the experimental plots will be treated with capsaicin. Our seed coat treatment structure will include three treatment levels and will closely follow the experimental design and seed coating techniques outlined in our previous work (Pearson et al. 2019). Seeds will be receive either 1) a seed coat clay treatment containing capsaicin powder, 2) a seed coat clay treatment without additives (to account for the influence of coating material on seed germination and foraging, independent of capsaicin), and 3) seeds that lack coating or taste deterrents (Fig. 8). Pilot greenhouse studies will be conducted to determine if seed coat treatments significantly influence the germination capacity and growth rate of native trees.Feeding deterrents will also be important at later juvenile tree life stages (Monteith et al. 2019). Consequently, in the spring and summer 2022, we will randomly choose three seedlings of each species in each subplot to receive a capsaicin spray treatment (5 mg capsaicin/1 L DiH20); another three seedlings of each species in each plot will receive a water spray control. Leaves of treated plants will sprayed every two weeks with a capsaicin treatment from early April until late June (six total applications per plant). All leaves will be sprayed until the leaves are saturated (~12-20 mL). Treated and untreated plants will be marked with identifying tags.

Progress 05/01/22 to 04/30/23

Outputs
Target Audience:Our work can inform best practices for forest management. This applies to managers at the federal, state, or regional level. Our target audience includes individuals interested in the conservation, restoration, management, and ecology of forest ecosystems in the upper Midwest. This includes county, city, state, and federal scientists, staff at NGOs, graduate and undergraduate students, as well as members of the public. To this end, in the last year, we have had extensive contact with members of our target audience. Specifically, we have communicated with staff from (number of staff in parentheses): Wisconsin Department of Natural Resources (30), City of Middleton (2), City of Madison (1), Milwaukee county parks (2), Waukesha count (1), Forest Exploration Center (non-profit) (2), Madison Metro School District (2), Milwaukee School District (3), University of Wisconsin-Madison/USDA (1), Southeastern Wisconsin Invasive Species Consortium (6), River Revitalization Foundation (non-profit; 1), UW-Parkside (2), The Nature Conservancy (1), Southeastern Wisconsin Regional Planning Commission (2). Multiple UW-Madison graduate students and undergraduates have worked directly on our project, and we have engaged members of the general public by developing an iNaturalist project entitled the "Southeastern Wisconsin Biodiversity Project" where members of the research team log geo-referenced observations of native and nonnative plants, animals, and fungi. These observations are linked to a publicly available global biodiversity database that allows anyone (e.g., researchers, policy-makers, educators) ask and answer questions about species range and phenology on a national and global scale. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?During this reporting year this project has supported the training and professional development of two postdoctoral researchers, three graduate students, and two undergraduate students. This project has supported dissertation and thesis research of the graduate students and a senior honors thesis for one of the undergraduate students. How have the results been disseminated to communities of interest?To discuss the project and determine how our objectives can best align with forestry management goals, we have communicated with 55 total staff from the Wisconsin DNR, two non-profit educational organizations, the Nature Conservancy, multiple school districts, two universities, three city/county parks departments, and the Southeastern Wisconsin Invasive Species Consortium (SEWISC). Our sites are also located on land owned and managed by these entities. These conversations have allowed us to understand historic management at these sites. We have also begun to engage with the public about the goals and results from the project including one presentation at the Forest Exploration Center. Communication about native and non-native species occurrence and distribution is an important aspect of our project. Consequently, we have developed an iNaturalist project entitled the "Southeastern Wisconsin Biodiversity Project" where members of the research team log geo-referenced observations of native and non-native plants, animals, and fungi. These observations are linked to a publicly available global biodiversity database that allows anyone (e.g., researchers, policymakers, educators) ask and answer questions about species range and phenology on a national and global scale. The Southeastern Wisconsin Biodiveirsty Project iNaturalist project (https://www.inaturalist.org/projects/southeastern-wisconsin-biodiversity-project) is an ongoing effort across southeastern Wisconsin that has logged 448 geo-referenced and time stamped observations including 214 unique species amassed by four researchers within the project (BMC, CA, MK, CK). In the reporting period, we also published several manuscripts from our project (Lanni et al. 2023, Keller and Orrock 2023). We also have a manuscript currently in review at Ecological Applications (Fuka and Orrock), as well as two additional manuscripts that are likely to be submitted in the next month. What do you plan to do during the next reporting period to accomplish the goals?We plan to continue collecting data on tree seedling survival, plant and tree seed survival, and plant community composition. We are also actively analyzing data from the last year and preparing manuscripts for submission (e.g., we have a manuscript currently drafted describing changes in plant communities following invasive shrub removal, and how the shift in communities depends on forest context).

Impacts
What was accomplished under these goals? We describe our accomplishments for this reporting period as they relate to each of the three aims of our study. Aim #1: Determine the unique and interactive effects of invasive shrubs and herbivores on tree regeneration in multiple forest contexts 1. Identification of study sites, delineation of plots, and invasive shrub removal started in August 2021 and was completed in July 2022. Urban sites were those where greater than 50% of the surrounding landscape was developed vs less than 10% for both agricultural and rural sites. Agricultural sites were characterized by greater than 25% of the surrounding landscape in agricultural use compared to less than 5% for urban and rural sites. Rural sites were characterized by greater than 40% of the surrounding landscape consisting of forested habitats vs less than 25% for agricultural and urban sites. We selected 16 sites to establish our experiments, 6 sites surrounded by urban landscapes, 5 sites surrounded by rural landscapes, and 5 sites surrounded by agricultural landscapes. 2. At each site we established two 20 by 20m plots. In one of these plots all invasive shrubs were removed at ground and remaining stems were treated to eliminate regrowth. The other plot was left intact as a control. To address our goal of understanding granivore and herbivore effects on plants and trees, we have installed exclosures in each plot that prevent or allow access by seed predators.To address our goal of understanding granivore and herbivore effects on plants and trees, we have installed exclosures in each plot that prevent or allow access by seed predators. In Fall 2022 we sowed seeds of six tree species into these exclosures (red oak, white oak, black cherry, sugar maple, red pine, and white pine). These six species are native to Wisconsin and are commonly seeded or planted by the Wisconsin DNR. This spring and summer (2023), we have monitored these plots for granivory and tree recruitment and will also continue to track changes in naturally recruiting trees and shrubs at each site, as per the methods in our proposal. To quantify how consumers affect the survival and growth of oak saplings, we installed 32 2x2m exclosures across the 16 sites. We planted 128 red oaks and 128 white oaks. We took growth, survival, and herbivory data on all of these planted trees. We have also conducted additional seed-removal studies to understand seasonal variation in the effect of invasive shrubs on predation of tree seeds, examining rodent and arthropod granivory of three native tree species:basswood (Tilia americana), black cherry (Prunus serotina), and sugar maple (Acer saccharum), and the invasive shrub R. cathartica. The manuscript describing these results is now in review at Ecological Applications. Differences in animal communities are a key component of understaning how consumer pressure is changing and affecting plant and tree regeneration. To characterize how animal communities might differ among the different forest contexts, we have collected 396,450 photos across 62 cameras since August of 2022. Wildlife Images has identified 93,084 of these as wildlife images, and roughly 88,000 as mammal photos. So far we have detected White-tailed Deer, Virginia Opossum, Northern Raccoon, Coyote, Domestic Cat, Domestic Dog, Striped Skunk, Red Fox, Bryant's Fox Squirrel, Eastern Grey Squirrel, Deer mouse, Eastern cottontail. Aim #2: Quantify the effect of invasive shrubs and herbivores on understory plant diversity in multiple forest contexts 1. We collected extensive baseline data on plant communities, surveying 128 1x1m vegetation plots where we estimated percent cover of all plant species and surveying 32 20 x 20m plots to create species inventories for each site. We have continued to conduct these surveys to assess how vegetation and plant communities are changing over time following the removal of invasive shrubs in our shrub-removal experiment. In total we found 152 unique plant species across the study. 2. As part of our work to understand how invasive shrubs modify seed predation on understory plants, we also discovered that invasive shrubs not only affect granivory on understory shrubs, but they also affect consumption of cocoons of invasive worms (Keller and Orrock, 2023). Aim #3: Evaluate the utility of classic and novel mitigation strategies to find optimal strategies in each forest context 1. We have conducted several studies to evaluate how capsaicin affects the removal of tree (Prunus serotina) seeds. This work is now completed and a manuscript is in preparation for submission. 2. We have also analyzed data from other capsaicin-coating trials with tree seeds in sites in Wisconsin and Michigan as part of this work. These results are now published in the Canadian Journal of Forest Research (Lanni et al.)

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Fuka M, Orrock, JL. 2023. Seasonal variation in small mammal granivory of native tree species reveals an optimal window for seed additions in the absence of invasive woody shrubs. Society for Ecological Restoration Midwest Great Lakes Chapter Meeting. Baraboo, WI.
• Type: Conference Papers and Presentations Status: Published Year Published: 2023 Citation: Fuka M, Orrock, JL. 2023. Seasonal variation in small mammal granivory of native tree species reveals an optimal window for seed additions in the absence of invasive woody shrubs. Ecological Society of America 180th Annual Meeting. Portland, OR.
• Type: Journal Articles Status: Awaiting Publication Year Published: 2023 Citation: Keller, C. B. and J. L. Orrock. In press. Removal of invasive shrubs reduces rodent consumption of non-native invasive animals and native understory seeds. Biological Invasions.
• Type: Journal Articles Status: Under Review Year Published: 2023 Citation: Fuka M, Orrock, JL. In review. Invasive shrubs amplify seasonal granivory, revealing optimal windows for seed survival following invasive shrub removal. Ecological Applications.
• Type: Journal Articles Status: Awaiting Publication Year Published: 2023 Citation: Lanni, F., Connolly, B. M., J. L. Orrock, , and P. W. Guiden. In press. Seed coatings containing capsaicin reduce seed removal of temperate woody species. Canadian Journal of Forest Research.

Progress 05/01/21 to 04/30/22

Outputs
Target Audience:Our work can inform best practices for forest management. This applies to managers at the federal, state, or regional level. Our target audience includes individuals interested in the conservation, restoration, management, and ecology of forest ecosystems in the upper Midwest. This includes county, city, state, and federal scientists, staff at NGOs, graduate and undergraduate students, as well as members of the public. To this end, in the last year, we have had extensive contact with members of our target audience. Specifically, we have communicated with staff from (number of staff in parentheses): Wisconsin Department of Natural Resources (30), City of Middleton (2), City of Madison (1), Milwaukee county parks (2), Waukesha count (1), Forest Exploration Center (non-profit) (2), Madison Metro School District (2), Milwaukee School District (3), University of Wisconsin-Madison/USDA (1), Southeastern Wisconsin Invasive Species Consortium (6), River Revitalization Foundation (non-profit; 1), UW-Parkside (2), The Nature Conservancy (1), Southeastern Wisconsin Regional Planning Commission (2). Multiple UW-Madison graduate students and undergraduates have worked directly on our project, and we have engaged members of the general public by developing an iNaturalist project entitled the "Southeastern Wisconsin Biodiversity Project" where members of the research team log geo-referenced observations of native and non-native plants, animals, and fungi. These observations are linked to a publicly available global biodiversity database that allows anyone (e.g., researchers, policy-makers, educators) ask and answer questions about species range and phenology on a national and global scale. To date, our team has logged 378 unique observations in Southern Wisconsin representing 181 unique species and our data collection efforts will continue for the duration of this project. Changes/Problems:Despite challenges of working within COVID-19 restrictions, we were able to locate and select our sites. However, because our site ownership varied (e.g., some owned by local governments, some by universities, some by WI DNR), the permitting process required more personnel time and effort than we had originally anticipated. For example, because many of the boards and permitting committees met less frequently because of COVID-19 restrictions, it took longer to get permission to work at sites. As a result, and although we had all of our sites selected on schedule, we were unable to start work at our sites until this spring. We also made slight alterations to the experimental design. The new design uses less fencing and is a more robust approach for answering our research questions. This change will also save on material costs, time, and space within the plot. As part of our study, we will be planting tree seedlings to observe how herbivory affects tree survival in urban, rural, and agricultural forests. We had originally planned on initiating these plantings this fall. However, because of the timing of seedling availability and COVID-related delays in getting our plots established, we will initiate this experiment in spring of 2023. This decision will not influence our ability to examine our research questions, as this leaves ample time (multiple seasons) to assess herbivory and seedling survival. After talking with numerous state foresters about the tree species that are most important to them (and those most often the focus of restoration efforts), we have made slight modifications to tree seed selection to align more closely with DNR priorities. We now plan to sow seeds of six tree species that are commonly sown in reforestation and management projects. Our tree planting will now include two species, red and white oak, which are the two most commonly planted tree species in southern Wisconsin, as well as red pine, white pine, sugar maple, and either hackberry or silver maple. This shift in some of our focal species will still allow us to achieve our original research objectives, while improving our ability to inform management of species that are known to be the primary focos of current and future on-the-ground efforts. What opportunities for training and professional development has the project provided?During this reporting year this project has supported the training and professional development of one postdoctoral researcher, two graduate students, one incoming graduate student, and five undergraduate students. This project has supported dissertation and thesis research of the two graduate students and a senior honors thesis for one of the undergraduate students. How have the results been disseminated to communities of interest?To discuss the project and determine how our objectives can best align with forestry management goals, we have communicated with 55 total staff from the Wisconsin DNR, two non-profit educational organizations, the Nature Conservancy, multiple school districts, two universities, three city/county parks departments, and the Southeastern Wisconsin Invasive Species Consortium (SEWISC). Our sites are also located on land owned and managed by these entities. These conversations have allowed us to understand historic management at these sites. We have also begun to engage with the public about the goals and results from the project including one presentation at the Forest Exploration Center. Communication about native and non-native species occurrence and distribution is an important aspect of our project. Consequently, we have developed an iNaturalist project entitled the "Southeastern Wisconsin Biodiversity Project" where members of the research team log geo-referenced observations of native and non-native plants, animals, and fungi. These observations are linked to a publicly available global biodiversity database that allows anyone (e.g., researchers, policy-makers, educators) ask and answer questions about species range and phenology on a national and global scale. To date, our team has logged 378 unique observations in Southern Wisconsin representing 181 unique species and our data collection efforts will continue for the duration of this project. What do you plan to do during the next reporting period to accomplish the goals?We describe our future plans as they relate to each of the three aims of our study. Aim #1: Determine the unique and interactive effects of invasive shrubs and herbivores on tree regeneration in multiple forest contexts To address our goal of understanding granivore and herbivore effects on plants and trees, we have installed exclosures in each plot that prevent or allow access by seed predators, for a total of 120 exclosures. This fall we will sow seeds of six tree species into these exclosures. These six species are native to Wisconsin and are commonly seeded or planted by the Wisconsin DNR. We will monitor these plots for granivory and tree recruitment and will also continue to track changes in naturally recruiting trees and shrubs at each site, as per the methods in our proposal. Aim #2: Quantify the effect of invasive shrubs and herbivores on understory plant diversity in multiple forest contexts We have collected extensive baseline data on plant communities and will continue monitor understory plant diversity using the same surveys in the coming year. Aim #3: Evaluate the utility of classic and novel mitigation strategies to find optimal strategies in each forest context In August and September 2022 we will deploy a seed-removal experiment using black cherry (Prunus serotina) seeds. Black cherry is native to Wisconsin and commonly found in our sites. We will coat these seeds with capsaicin, the compound that makes chili peppers hot, and has been shown to deter mammalian seed predators. This experiment will contain five different treatments: 1) uncoated seeds, 2) seeds coated with clay but no capsaicin, 3) seeds coated with clay and capsaicin, 4) seeds coated with wilt-pruf, and 5) seeds coated with wilt-pruf and capsaicin. This experiment will allow us to test the effectiveness of capsaicin as a seed predator deterrent as well as the effectiveness of different seed coating methods (clay or wilt-pruf) which are necessary for the capsaicin to stick to the seed. This method will be tested using a total of 150 seed removal depots in an urban forest in Madison Wisconsin and will directly inform larger in-situ trials of the method at our experimental plots. We anticipate the completion of data collection by Spring 2023. These results will help inform the effectiveness of capsaicin as a seed predator deterrent in different forest types (urban, rural, and agricultural) with and without invasive shrubs present.

Impacts
What was accomplished under these goals? We describe our accomplishments for this reporting period as they relate to each of the three aims of our study. Aim #1: Determine the unique and interactive effects of invasive shrubs and herbivores on tree regeneration in multiple forest contexts Identification of study sites, delineation of plots, and invasive shrub removal started in August 2021 and was completed in July 2022. As part of this process we identified over 180 sites in southern Wisconsin and visited these sites to determine suitability for our study. For sites that were promising based upon on field reconnaissance, we used an extensive landscape-analysis approach to characterize and select our final group of sites, buffering each site by 500m and comparing the proportion of each buffer composed of different land-use types. Urban sites were those where greater than 50% of the surrounding landscape was developed vs less than 10% for both agricultural and rural sites. Agricultural sites were characterized by greater than 25% of the surrounding landscape in agricultural use compared to less than 5% for urban and rural sites. Rural sites were characterized by greater than 40% of the surrounding landscape consisting of forested habitats vs less than 25% for agricultural and urban sites. We selected 15 sites to establish our experiments, 6 sites surrounded by urban landscapes, 5 sites surrounded by rural landscapes, and 4 sites surrounded by agricultural landscapes. At each site we established two 20 by 20m plots. In one of these plots all invasive shrubs were removed at ground and remaining stems were treated to eliminate regrowth. The other plot was left intact as a control. To address our goal of understanding granivore and herbivore effects on plants and trees, we have installed exclosures in each plot that prevent or allow access by seed predators and will initiate these experiments in fall 2022 (see future plans for additional details). As of August 2022, we have collected data on soils (compaction and cores for total C, N, and texture), light availability (photosynthetically active radiation taken at 5 locations and 2 heights at each site), tree density (stem counts and DBH), and shrub density (stem counts) to help us better understand the existing tree and shrub communities at these sites. We have just completed data collection and are currently entering and proofing data. For example, our data indicate that our sites contained 30 unique woody plant species large enough to be included in our DBH measurements (i.e., woody plants large enough to be in the forest canopy or subcanopy). Aim #2: Quantify the effect of invasive shrubs and herbivores on understory plant diversity in multiple forest contexts To address this goal, in June and July 2022 we measured the abundance of all understory plan species in each plot in four 1 by 1m quadrats, for a total of 120 plots. We also completed an inventory of all understory plant species that occurred in each 20 by 20m plot. We completed data collection in July 2022 and are currently in the process of data cleaning, storing, and summarizing. Our efforts were exhaustive and captured significant understory diversity and variation. For example, during our vegetation surveys we recorded145 unique plant species. Aim #3: Evaluate the utility of classic and novel mitigation strategies to find optimal strategies in each forest context We have designed the experiment we will use to test the efficacy of capsaicin coating as a means to reduce granivory of tree seeds and increase recruitment. We have also assembled all of the materials needed to conduct this experiment and will soon deploy the experiment in the field (see future plans for additional information).

Publications

• Type: Journal Articles Status: Published Year Published: 2022 Citation: Bartel, S. L., & Orrock, J. L. (2022). The important role of animal social status in vertebrate seed dispersal. Ecology Letters, 25(5), 1094-1109.
• Type: Journal Articles Status: Published Year Published: 2022 Citation: Marsack, J, and BM Connolly (2022). Generalist herbivore response to volatile chemical induction varies along a gradient in soil salinization. Scientific Reports, 12:1689 https://doi.org/10.1038/s41598-022-05764-0
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Connolly, BM (2021). Collection age and seed mass influence germination and seedling growth in Midwestern white spruce accessions. Forest Science, 67 (6): 637-641 https://doi.org/10.1093/forsci/fxab038
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Connolly, BM (2021). The very hungry (and bold) caterpillar  A classroom experiment testing relationships between animal behavior and herbivory. Teaching Issues and Experiments in Ecology, V17: Exp. #1
• Type: Journal Articles Status: Under Review Year Published: 2022 Citation: Keller, C.B. and J.L. Orrock. In review. Invasive shrubs increase native consumer pressure on exotic animals and native understory plants.