COS 62-8 - Comparative experimental biogeography of invasive alien and native plant species pairs using integral projection models

Tuesday, August 7, 2012: 4:00 PM
E143, Oregon Convention Center
Sarah Treanor Bois, Conservation Research, Institute for Applied Ecology, Corvallis, OR, Jenica M. Allen, Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, Cory Merow, Quantitative Ecology Group, Smithsonian Environmental Research Center, Edgewater, MD, Ines Ibanez, School of Natural Resources and Environment, University of Michigan, Ann Arbor, MI and John A. Silander, Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT
Background/Question/Methods

As part of a multi-scale project to predict invasive plant spread in response to climate and land-use change, we used experimental biogeography to evaluate a suite of environmental conditions, mitigated by demography, which may facilitate the establishment of three invasive alien species (IAS). Species distribution models have highlighted areas of northern New England, currently lacking IAS, as places where these species may potentially thrive. However, as these IAS move northward, they will encounter novel conditions affecting establishment and growth. How species’ population dynamics respond to these novel conditions will influence their further spread and potential impact across the region. We established regional transplant experiments to test species distribution model results and to estimate the colonization potential for representative IAS, Berberis thunbergii and Alliaria petiolata, compared to two native analogues, Lindera benzoin and Arabis glabra. We investigated the response of each species’ vital rates to the environmental gradients using linear regression models. We then built demographic Integral Projection Models (IPMs) for our study species from these regressions to assimilate demographic information and make population-level predictions.

Results/Conclusions

Results indicate that the invasive species tolerate a broad climate gradient across New England. The invasives were able to germinate, survive, grow and, in some cases, reproduce in northern New England outside of their current known distributions, validating the results of previous model predictions. Across the species pairs, the invasives had a much higher rate of germination in the field than their native analogs. Of those that germinated, the invasives had a greater rate of survival to seedling regardless of environment. At later demographic stages, the invasives overall also had greater rates of survival and growth. The resulting population growth rates varied by environment, in some cases drastically. These results  highlight the necessity in taking microsite variation into account when calculating population dynamics. The observed responses for each vital rate enable us to make predictions about survival, reproduction, and population growth rate and assess how IAS may respond to a changing environment.