ESTIMATING BUCKTHORN ABUNDANCE ACROSS WISCONSIN TO EXPLORE ITS USAGE IN THE BIOENERGY SECTOR TO MITIGATE ITS INVASION

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: MCINTIRE-STENNIS
• Reporting Frequency: Annual
• Accession No.: 1024660
• Project Start Date: Nov 2, 2020
• Project End Date: Sep 30, 2021
• Program Code: [(N/A)]- (N/A)

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

Performing Department
UWSP College of Natural Resources

Non Technical Summary
Two invasive species, common buckthorn (Rhamnus cathartica) and glossy buckthorn (Frangula alnus), are now prevalent throughout Wisconsin and occur in many community types. It is important for land managers to manage buckthorn to maintain healthy ecosystems. Current control methods are cost prohibitive and are mainly limited to cutting and/or spraying the buckthorn; however, it can aggressively re-sprout. Buckthorn biomass could instead be used in the bioenergy sector, mitigating the high cost of removal while simultaneously increasing the monetary value of the ecosystem services. The objectives of this study is to develop a statistical model to estimate the abundance of buckthorn across the state of Wisconsin, which will support the ultimate goal of evaluating the feasibility of utilizing buckthorn as a feedstock for bioenergy production. Data on buckthorn abundance will be collected through field work across Wisconsin in collaboration with LEAF: Wisconsin's K-12 Forestry Education Program.Nine landscape variables and three forest-level variables will be used to build two models - one for buckthorn presence and a second to estimate abundance. The models will be validated and used to develop a map showing buckthorn distribution and abundance across Wisconsin. This information will be useful for land use planners and land managers who wish to reduce buckthorn invasion. It will also be helpful for choosing areas to harvest. This information will ultimately be used to conduct feasibility study for utilizing buckthorn biomass in the bioenergy sector.

Animal Health Component

40%

Research Effort Categories

Basic

50%

Applied

40%

Developmental

10%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
123	0610	1070	33%
123	0613	1070	33%
123	0620	1070	34%

Knowledge Area
123 - Management and Sustainability of Forest Resources;

Subject Of Investigation
0610 - Conifer forests of the North; 0620 - Broadleaf forests of the North; 0613 - Mixed conifer-broadleaf forests;

Field Of Science
1070 - Ecology;

Keywords

common buckthorn

glossy buckthorn

buckthorn abundance

bioenergy

biomass harvesting

Goals / Objectives
The goal of the project is to explore the potential of utilizing invasive buckthorn species in the bioenergy sector across Wisconsin. Harvesting and processing buckthorn in an economically feasible manner would mitigate the high cost incurred to eradicate such invasive species in order to improve ecosystem services. Such analysis would require data on distribution and abundance of buckthorn across the state, and energy-related properties of the plant. The specific objectives of the project are to:Predict the presence and to the estimate the abundance of buckthorn in school forests across the state of WisconsinEstimate the energy related properties of buckthornConduct supply chain cost analysis of utilizing buckthorn biomass as a feedstock to produce bioenergy using different energy conversion pathways

Project Methods
During the summer of 2020, a stratified random sample of school forests will be inventoried across the state of Wisconsin. The number of samples will depend on the size of the school forest and the stability of the running mean of buckthorn density. We will allocate one-quarter of the samples to edge environment. At each sample location, two nested plots will be established. The plots will have radii of 3 m and 7 m. Within the 3 m radius plots, the heights and diameters at breast height (DBH) of all common buckthorn plants will be measured. In the 7 m fixed radius plots, only buckthorn taller than one meter will be measured for height and DBH. The abundance and DBH of all other woody species will also be recorded in the 7 m radius plot as well as the index o of light level from a densiometer. Independent variables recorded in the field includelight levels, habitat type, as well as basal areaof all other woody species.The landscape variables to be estimated with GIS include: 1) land use around the forest, 2) number of sides with 'hard' edges, 3) distance to nearest road, 4) distance to nearest house, 5) extent of habitat fragmentation, 6) distance to nearest similar forest type, 7) forest shape, 8) housing density within 1 km and 9) road density within 1 km. Regressionwill be used to determine variables that have significant effect on buckthornpresence or abundance.Logistic regression will be utilized to predict presence, and multiple linear regression for the prediction of abundance. Variables that have a significant correlation with buckthorn presence or abundancewill allow us to build models to determine which combination of forest type, woody basal area, soil type and landscape characteristics most accurately predict where buckthorn is likely to occur and how abundant it will become. The models will then be tested with an independent data set confirm or refine their accuracy in predictingbuckthorn presence or abundance.Samples of buckthorn will be collected to determine its calorific value, ash content and specific gravity for use in the bioenergy sector. Samples will be weighed immediately after cutting to obtain their fresh weight using a portable electronic scale and will then be tagged and put into paper bags to be brought to the lab and dried at 70oC for 72 hours. Calorific values will be determined in a bomb calorimeter following the protocols used by the Wisconsin Institute for Sustainable Technology (WIST). Ash content determination will also follow laboratory procedures provided by WIST. Specific gravity will be determined by submerging samples in a beaker of water.Estimated abundance of biomass and heating values will be used to determine if buckthorn wood could be used as a viable source of bioenergy. The outputs and inputs of the system need to be considered and analyzed. Output of the system is the amount of energy created from burning buckthorn as either pellets, biochar, or hog fuels in an energy generating plant. The input of the system includes all the fixed and variable costs that goes into harvesting and transporting buckthorn. The cost analysis will be carried out for the following options for processing buckthorn biomass: (i) Grinding, (ii) mobile pelletizer and (iii) mobile pyrolysis unit.

Progress 11/02/20 to 09/30/21

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?A graduate student at the master's level was trained through this project. The graduate students presented findings are several conferences. Additionally, three undergraduate students were involved in this project: Colby Powers, Matthew Masterlier and Amanda Krieg during data compilation and analysis phase. Students presented the project at the University of Wisconsin - Stevens Point (UWSP), College of Natural Resources Undergraduate Symposium. How have the results been disseminated to communities of interest?Two scientific publications were shared with Wisconsin Center for Environmental Education (WCEE) which is housed at UWSP. WCEE subsequently shared the findings with school forests across Wisconsin who are the landowners and responsible for managing forests. The results have also been presented at several conferences and events: Boettcher, T.J., Gautam, S. and Cook, J. 2021. Exploring the viability of utilizing invasive buckthorn for bioenergy production: an avenue towards eradication. Small-scale Forestry Research in challenging Times, Virtual IUFRO Conference Freiburg, Germany, February 9-11, 2021. Boettcher, T.J., Gautam, S. and Cook, J. 2021. Eradicating buckthorn through its utilization in bioenergy production. SAF UWSP student chapter. Stevens Point, April 1. Powers, C., Gautam S. and Boettcher TJ. 2021. Factors affecting the presence of invasive buckthorn (Rhamnus cathartica & Frangula alnus) in Wisconsin school forests. 2021 Jim and Katie Krause CNR Student Research Symposium, University of Wisconsin-Stevens Point, April 9. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Weconstructed a series of regression models including binomial regression for the probability of occurrence of buckthorn, and Poisson and negative binomial regression to model abundance using a two- phase, zero-inflated approach with several explanatory variables. The modelling of buckthorn presence and abundance were developed usingcertainlandscape-level and stand-level variables as predictors in Wisconsin. The resulting zero-inflated model indicated that stem density, species diversity, and mean diameter at breast height of woody species (not including buckthorn), as well as distance to nearest house, housing density within 1 km, solar irradiation, percent silt, and latitude were important for estimating buckthorn presence and abundance. The models developedin this studyand published can guide land managers on where to target mitigation actions by identifying areas invaded by buckthorn. Land developers could also take into consideration disturbance-related variables as a means to avoid new infestations of buckthorn. Areview was subsequently conducted to determinethe state of the knowledge on the effects of buckthorn and its cost associated with major ecosystem services. In the same review, existing methods to harvest and transport buckthorn and potential new methods were compiled for its use in the bioenergy sector. It was established that buckthorndirectly affects the raw materials of an ecosystem by crowding out trees and reducing biomass that the forest industry relies on. These costs can be quantified by estimating the value of timber or biomass that could potentially be contained within a property without buckthorn. It may be possible for buckthorn itself to be used as raw material for biomass production in the form of chip, pellets, or biochar, but more information needs to be gathered on the qualities of buckthorn wood to determine if these options are feasible. If they are feasible then it may be possible to reduce costs of removing buckthorn while also increasing economic value of land. Preliminary supply chain analysis wasconducted to establish the most cost-efficient harvesting, processing, and transportation methods to procure buckthorn biomass.

Publications

• Type: Journal Articles Status: Published Year Published: 2022 Citation: Boettcher, T. J., Rijal, B., Cook, J., & Gautam, S. (2022). Modeling the presence and abundance of buckthorn across the forests of Wisconsin, USA using different regression techniques. Forest Ecology and Management, 506, 119960.
• Type: Journal Articles Status: Published Year Published: 2021 Citation: Boettcher, T. J., Gautam, S., & Cook, J. (2021). The Impact of Invasive Buckthorn on Ecosystem Services and Its Potential for Bioenergy Production: A Review. Journal of Sustainable Forestry, 1-23.