PARENT SESSION
Contributed Oral Session 134: Forest Ecology: Reproduction and Recruitment
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 516 D, Level 5, Palais des congrès de Montréal
Predicting tree seedling recruitment of resident and potential immigrant species under climate change.
Ibáñez, Inés*,1, Clark, James1, Dietze, Michael1, 1 Duke University, Durham, NC
ABSTRACT- Predicting future distribution patterns of plant populations most models focus on the growth responses to climate and dispersal capability. However, more reliable forecasts will require knowledge of the performance of potential immigrant species relative to residents. To obtain this information, we planted tree seedlings of residents and potential immigrant species side by side in two regions of the southeast USA, the North Carolina Piedmont and the Southern Appalachians Mountains, within experimental treatments representative of regional environmental heterogeneity. We estimated how seedling survival is affected by environmental variables related to climate change, including soil moisture, ground vegetation cover, light levels, winter minimum temperatures, canopy gaps, and exposure to herbivory. For both immigrant and resident species, seedling survival was higher in the Southern Appalachians than in the Piedmont, apparently due to higher moisture availability in the Appalachian sites. The magnitude and direction of the tree seedling response to the gradient of environmental variables they were planted under were complex and species specific. Five resident species in the Piedmont sites showed higher survival with higher soil moisture, also did three potential immigrants in the Southern Appalachians. Growing in a canopy gap only benefited one resident pine species in the Southern Appalachians, and five other species, resident ones, experienced decreased survival. Reduced exposure to herbivores at the Piedmont site increased survival of only resident species. These results show that seedling survival under an array of environmental variables will vary greatly from one species to another, making the response of the whole community quite complex. If we want to predict changes in vegetation accurately, we will therefore need to consider species specific performance relative to competitors in our models.
Key words: seedling survival, climate change, potential immigrant, competition