Ubiquitous germination among common perennial species in response to facilitated and unfacilitated microhabitats

摘要

We present results from a study that examines species-specific facilitation of germination in an arid perennial community. This system suffered 64% adult mortality and the local extinction of two common species as a consequence of drought that occurred between 1999 and 2004. Ambrosia dumosa, Larrea tridentata, and Tetracoccus hallii are included as candidate benefactor species based on their high abundance and broad distribution at the study site. Using complementary field and greenhouse experiments, we measured the effects of facilitation, light and nitrogen on germination of four species common to the region, L. tridentata, A. dumosa, Sphaeralcea ambigua and Eriogonum fasciculatum.