Dissertation Research: Life History Responses to Fire in a Clonal Herb, Pityopsis graminifolia

目前尚不清楚频繁、低频率等干扰是如何产生的 强度（例如亚致死）火灾影响了生命史 植物的进化 禾叶藓是一种适应火的， 一种多年生无性繁殖草本植物，栖息于经常燃烧的沙丘上 长叶松热带稀树草原东南部。 繁殖生物学 在两个沙丘群落中， 尽管火灾导致的后果很小， 成虫死亡率或幼苗建立在任一社区。 拟议的研究有两个主要目标。 它将首先检查 低强度火灾如何改变环境的可持续性 这两个沙丘种群的条件。 具体来说，如果火灾以及火灾在多大程度上降低了 开花和营养繁殖（如克隆生长），在这 通过增加养分的可利用性， 将对每个社区进行检查。 的影响 花食草动物和种子捕食火灾后，在每一个这些 此外，亦会研究地盘。他们的影响的重要性， 根据繁殖行为的表型变异 在这些沙丘的火灾后， 将对社区进行评估。 结果可能表明， 植物生命期的环境条件影响植物的寿命 历史演变 研究的第二个目标是解决如何 开花和克隆生长的动力学响应于火灾， 不同的历史，进化的重要性（如增长） 季节与休眠季节火灾）。 尤其是， 大量开花和结果，持续时间短， 历史上重要的生长季节火灾减少了 花草食动物和/或种子捕食在这个物种将是 评估。 这类证据可以提供关于 生长季与休眠季适应意义 长叶松草原的亚致命火灾。

It is not well understood how disturbances such as frequent, low- intensity (e.g. sublethal) fire have influenced life history evolution in plants. Pityopsis graminifolia is a fire-adapted, clonal perennial herb that inhabits frequently burned sandhills in Southeastern longleaf pine savannas. The reproductive biology of this species differs in two sandhill communities in which it has been studied despite the fact that fire results in little adult mortality or seedling establishment in either community. The proposed study has two major objectives. It will first examine how low intensity fires change the favorability of environmental conditions in these two sandhill populations of P. graminifolia. Specifically, if and to what extent fire reduces the cost of flowering and vegetative reproduction (e.g. clonal growth) in this stress-tolerant species by increasing the availability of nutrients in each of these communities will be examined. The impact of floral herbivory and seed predation following fire in each of these sites will also be examined. The significance of their impact in light of the phenotypic variation in reproductive behavior exhibited by this species following fires in each of these sandhill communities will be assessed. Results may indicate how fluctuating environmental conditions during the life of a plant influence life history evolution. The second goal of the study is to address how the dynamics of flowering and clonal growth respond to fires that differ in their historical, evolutionary importance (e.g. growing season vs. dormant season fires). In particular, whether the more profuse flowering and fruiting of shorter duration following historically important growing season fires reduces the impact of floral herbivory and/or seed predation in this species will be assessed. Evidence of this kind could provide insight regarding the adaptive significance of growing season vs. dormant season sublethal fires in longleaf pine savannas.