COS 76-7 - Environmental factors that differentially affect the life stages of small forest herbaceous populations

Wednesday, August 10, 2011: 3:40 PM
9C, Austin Convention Center
Danielle M. Racke, Biology, University of Virginia, Charlottesville, VA and Albert J. Meier, Biology and Center for Biodiversity Studies, Western Kentucky University, Bowling Green, KY

Many herbaceous communities in secondary mesic forests support fewer species than otherwise similar primary forests. Some researchers have tested dispersal limitation and competitive limitation hypotheses with forest transplant and seed addition studies. However, few researchers have examined correlations between environmental characteristics and the relative success of different life stages of transplanted native herbs in forest habitats. Our study sought to assess the effects of a range of environmental conditions on the survival, self-propagation, and germination of spring-flowering herbaceous species in mesic hardwood forests. We transplanted 180 plants and 720 or 1800 propagules of each of five species into four mesic hardwood forests in which these species were previously absent. We measured several abiotic factors that we expected to influence survival and recruitment, including light, temperature, soil moisture, soil pH, and soil nutrients. We addressed the following questions. 1) Which life stage is the most limiting to introduced populations of each species?

2) Which abiotic environmental characteristics are most limiting to population expansion of each species? 3) Under what environmental conditions could transplanting or seed-sowing be an effective restoration method?


We found that subsequent seed production and seedling recruitment were the primary limiting factors for different subsets of species. We found species-specific correlations between soil nutrients and flowering, independent of the size of transplanted individuals. We also found correlations between soil nutrients and germination success. In addition to these results, we present transition matrices for each species and discuss the life stage at which each species seems most vulnerable to population recovery failure. We also discuss the conditions under which transplanting or seed-sowing may be more effective. Finally, we discuss the implications of our results for future restoration initiatives.

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