SGER: El Nino Rains as a Germination Cue for Desert Annuals

9810674龙德尔沙漠一年生植物一直是许多生态学家研究的重要群体，包括种群生物学家对生活史适应策略的建模。这些模型通常假定沙漠一年生植物采用一种下注-对冲策略，在这种策略中，当秋冬降雨后出现良好生长条件时，并非所有种子都能发芽。有限的数据表明，沙漠一年生植物有休眠机制，允许一种保守的策略，即种子库的子集在一系列年里发芽。许多荒漠一年生植物和火后灌木林一年生植物之间存在密切的系统发育关系，它们具有由化学信号决定的预测萌发策略，这表明荒漠一年生植物也可能存在预测萌发策略。该项目将调查来自加州冬季降雨的莫哈韦沙漠和科罗拉多沙漠的一些沙漠一年生植物中环境化学线索对发芽的影响。1997-1998年的厄尔尼诺现象提供了不寻常的条件，使常见和罕见的沙漠一年生植物都产生了大量的发芽和种子。

9810674 Rundel Desert annuals have been an important group for study by many ecologists, including population biologists modeling strategies of life history adaptations. Such models have generally assumed a bet-hedging strategy in desert annuals in which not all seeds germinate when good growing conditions occur following fall and winter rains. There are limited data suggesting that desert annuals have dormancy mechanisms that allow a conservative strategy in which subsets of seed pools germinate over a series of years. The close phylogenetic relationship between a number of desert annuals and post-fire chaparral annuals, which have a predictive germination strategy cured by chemical signals, suggests that predictive germination strategies may also be present among desert annuals. This project will be investigating the effect of environmental chemical cues for germination in a number of desert annuals from the winter-rainfall Mojave and Colorado Deserts in California. El Ni o conditions in 1997-1998 are providing unusual conditions which have produced abundant germination and seed set of both common and rare desert annuals.