PARENT SESSION
Oral Session #27: Fire Ecology.
Presiding: C. Allen
Tuesday, August 6. 8:00 AM to 11:30 AM. Graham Meeting Room, TCC.

Spatial and temporal components of desert annual seed germination.

Fotheringham, CJ^*,1, Nakamura, Robert², Rundel, Philip¹, Keeley, Jon³, ¹ University of California, Los Angeles, Los Angeles, CA² California State University, Los Angeles, Los Angeles, CA³ U.S. Geological Survey, Three Rivers, CA

ABSTRACT- Many recent studies have shown that species in fire-prone shrublands are stimulated to germinate in response to smoke. In the California chaparral some of the smoke stimulated species also occur, or have sibling species, in adjacent desert ecosystems. While there are no studies that address where post-fire annual come from there is a general consensus in the literature that they are derived from desert stock. California chaparral has temporal resource islands (recurrent fires) while the Mojave desert is characterized by resource islands with both a spatial (under vs between shrubs) and temporal (high rain years) components. Post-fire species, or closely related species, that occur in the desert are primarily located on high nutrient resources islands (under shrubs). To better understand exchange of species between these two communities, we tested the germination behavior of 31 species in the four most common Mojave annual plant families. We found that species that occur post-fire were also stimulated by smoke in desert populations. To better understand what factors in the desert are selecting for this behavior we used log-linear model and found that the factors family association (phylogeny) and microhabitat preference modeled 96% of the variation in seed germination patterns.

KEY WORDS: Germination, Smoke , desert , annual