Alpert, Holly , Loik, Michael E. .
Drivers of Pinus jeffreyi establishment at a conifer forest-sagebrush steppe ecotone in eastern California.
Climate change will have implications for species distributions and conservation of native flora. At the low-elevation treeline of the eastern Sierra Nevada in California, Pinus jeffreyi is a dominant conifer, and understanding the limitations of its distribution will assist us in predicting future movements of this ecotone. In this research, P. jeffreyi seedlings were planted in three microhabitat treatments (under co-dominant shrubs Artemisia tridentata and Purshia tridentata, and in open intershrub spaces) at two sites spanning the ecotone in 2006, 2007, and 2008. Survival was monitored throughout the growing season. Soil moisture, air and soil temperature, and irradiance were also measured in each of the microhabitats. Soil moisture decreased at both sites throughout each summer but was consistently higher at the higher elevation site. Shrub microhabitats generally exhibited less extreme air and soil temperature and irradiance conditions. Overall, less than one percent of seedlings survived longer than their first growing season. Seedling survival time was lower in 2007, which was a drought year, compared to 2006 (very wet) and 2008 (about average). Generally, seedlings growing in intershrub spaces suffered higher drought mortality, while more intense seedling herbivory occurred under shrubs. These results suggest that microhabitat is important for P. jeffreyi establishment and that the continuation of this species at the ecotone in a future climate will be closely linked to that of co-occurring shrub and herbivore species. Although shrubs played a facilitative role in providing safe sites for seedling establishment, they also provided opportunity for herbivory by rodents using shrubs for cover. Efforts to manage forest structure under climate change should consider recruitment niches and herbivory pressure.
Log in to add this item to your schedule
1 - University of California Santa Cruz, Environmental Studies, PO Box 504, Mammoth Lakes, CA, 93546
2 - University of California Santa Cruz, Environmental Studies, 1156 High St, Santa Cruz, CA, 95064
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Wasatch B/Cliff Lodge - Level C
Date: Monday, July 27th, 2009
Time: 4:15 PM