Weedy Plant Invasions

What are the causes and consequences of weedy plant invasions into temperate forest communities?

Exotic weeds threaten farms, pine and oak regeneration, and native plant diversity. Using uniquely comprehensive baseline data, we find large declines in tree regeneration and gains in invasive plants across Wisconsin over the past 50 years. Site and surrounding landscape conditions, exotic earthworms, and deer all appear linked to these invasions and native species losses.

We propose to extend this work to predict invasions into sites and the likely consequences of these invasions on tree regeneration and native plant diversity. To do this, we will first determine which site and landscape factors best predict the incidence and abundance of invading species. Additional field sampling will allow us to extend our surveys into highly invaded lowland forests and accurately assess the extent and impacts of invasive shrubs and earthworms. We will use GIS models to estimate how vulnerable given sites are to invasion and to create contour maps predicting vulnerability. Using data from this and previous projects and multivariate statistical models will allow us to evaluate the separate and combined effects of earthworms, garlic mustard, buckthorn, and honeysuckle on patterns of tree regeneration and native plant diversity. Finally, we will initiate experiments to determine how quickly tree regeneration and plant diversity recover in invaded forests once garlic mustard and exotic shrubs are removed.These results will enhance economic opportunities, improve the rural quality of life, and enhance our ability to protect and sustain our Nation’s natural resource base and environment (CREEES goals 2 and 5).

This project was supported by a National Research Initiative grant #2008-35320-18680 from the USDA National Institute of Food and Agriculture Biology of Weedy and Invasive Species program.

Related Publications

T.P. Rooney and D.M. Waller. 2008. Plant Diversity in the once and future Northwoods. In D.M. Waller & T.P. Rooney, eds., The vanishing present: Wisconsin’s changing lands, waters, and wildlife. Univ. of Chicago Press, Chicago.

Amatangelo, K.L, E.L. Mudrak, S.M. Klionsky, D.A. Rogers, and D. Waller. Do local effects of exotic species provide early signals of impending regional impacts on plant diversity? Association analyses from southern Wisconsin forests. Submitted, Journal of Ecology.

Crall, A.W., G.J. Newman, T.J. Stohlgren, K.A. Holfelder, J. Graham, and D.M. Waller. Assessing citizen science data quality: An invasive species case study. Submitted, Conservation Letters.

Klionsky, S., K. Amatangelo, and D.M. Waller. Above- and below-ground impacts of European buckthorn (Rhamnus cathartica L.) on four native forbs. Restoration Ecology. doi: 10.1111/j.1526-100X.2010.00727.x

Crall, A.W., G.J. Newman, C.S. Jarnevich, T.J. Stohlgren, D.M. Waller, and J. Graham. 2010. Improving and integrating data on invasive species collected by citizen scientists. Biological Invasions. DOI 10.1007/s10530-010-9740-9

Rooney TP, DA Rogers, S.M. Wiegmann, and DM Waller. 2004. Monitoring non-native plant invasions over fifty years in Wisconsin forests. Weed Technology 18: 1266-1268.