Predicting Ailanthus altissima presence across a managed forest landscape in southeast Ohio

Abstract

Background: The negative impacts of the exotic tree, Ailanthus altissima (tree-of-heaven, stink tree), is spreading throughout much of the Eastern United States. When forests are disturbed, it can invade and expand quickly if seed sources are nearby. Methods: We conducted studies at the highly dissected Tar Hollow State Forest (THSF) in southeastern Ohio USA, where Ailanthus is widely distributed within the forest, harvests have been ongoing for decades, and prescribed fire had been applied to about a quarter of the study area. Our intention was to develop models to evaluate the relationship of Ailanthus presence to prescribed fire, harvesting activity, and other landscape characteristics, using this Ohio location as a case study. Field assessments of the demography of Ailanthus and other stand attributes (e.g., fire, harvesting, stand structure) were conducted on 267 sample plots on a 400-m grid throughout THSF, supplemented by identification of Ailanthus seed-sources via digital aerial sketch mapping during the dormant season. Statistical modeling tools Random Forest (RF), Classification and Regression Trees (CART), and Maxent were used to assess relationships among attributes, then model habitats suitable for Ailanthus presence. Results: In all, 41 variables were considered in the models, including variables related to management activities, soil characteristics, topography, and vegetation structure (derived from LiDAR). The most important predictor of Ailanthus presence was some measure of recent timber harvest, either mapped harvest history (CART) or LiDARderived canopy height (Maxent). Importantly, neither prescribed fire or soil variables appeared as important predictors of Ailanthus presence or absence in any of the models of the THSF. Conclusions: These modeling techniques provide tools and methodologies for assessing landscapes for Ailanthus invasion, as well as those areas with higher potentials for invasion should seed sources become available. Though a case study on an Ohio forest, these tools can be modified for use anywhere Ailanthus is invading.

Long-term treatment leads to reduction of tree-of-heaven (Ailanthus altissima) populations in the Buffalo National River

“…Working at the scale of local populations, we demonstrated a high level of reduction of A. altissima in BNR with repeated chemical treatment using a strategy to prevent recruitment into the canopy. The patchy distribution of the plant on the landscape described in this study as well as by others (Polgar 2008, Rebbeck et al 2015) supports such self-limitation to areas of fallen and windthrown trees in the absence of fire or logging (Iverson et al 2019;Rebbeck et al 2017Rebbeck et al , 2019. These results suggest that we can mitigate future risks of A. altissima spread within these forests through actions taken now.…”

Restoration of diversity and regeneration of woody species through area exclosure: the case of Maun International Airport in northern Botswana

“…The presence of invasive species is not surprising as the site was previously a residential area and local communities might have introduced them as ornamental trees, whereas the area outside the MIA was a communal area that was used for animal grazing and harvesting of fuelwood. Ailanthus altissima (also known as prison tree and tree-ofheaven) is planted in many countries as an ornamental tree (Iverson et al 2019). It is an aggressive invader that spreads from root sprouts and grows rapidly to produce large quantities of seeds (Call & Nilsen 2005) that are wind dispersed (Bory & Clair-Maczulajtys 1980).…”

Non-native tree regeneration indicates regional and national risks from current invasions

“…This information can be used to tailor management approaches to individual species. Efforts to manage the problems associated with non-native invasive trees span local-scale efforts to control invasions and mitigate their efforts to systematic national-scale strategies aiming to both reduce current impacts and reduce the risk of future problems (Richardson and Rejmánek, 2011;Shackleton et al, 2017;Iverson et al, 2019). Specific management approaches for invasive woody plants include public education, mechanical treatments, herbicide applications, and the development of effective biological control agents (Webster et al, 2006).…”