Climate and Competition as Controls on the Persistence and Richness of an Edaphicendemic Flora

科学家们目前对全球气候变化将如何影响地域性植物或局限于某些不寻常的岩石或土壤中的植物知之甚少。在加利福尼亚，有超过200种植物局限于蛇形土壤，蛇形土壤是一种来自海洋地壳岩石的粗糙、营养贫乏的土壤。由于两个原因，土壤地方性植物可能特别容易受到气候变化的影响：因为它们被困在土壤“岛屿”上，因此不太能够改变它们的分布，而且因为恶劣土壤的影响可能会加剧不利气候的压力。我们将从两个方面来研究这个问题：(1)与它们的近亲相比，加利福尼亚特有的蛇形动物是否在更有利的气候条件下非随机发现；(2)通过对Klamath山脉（CA北部- OR西南部）55年的样带进行重新采样，探讨低海拔蛇形岩上的物种消失是否多于其他土壤或高海拔土壤。由于地域性对全球生物多样性的贡献很大，而且它们的地理分布不太可能符合标准气候模型的假设，因此这项研究将填补我们对全球气候变化对生物影响的理解中的一个重要空白。

Scientists currently know little about how global climate change will affect edaphic endemics, or plants that are confined to certain unusual rocks or soils. In California there are over 200 plant species confined to serpentine soils, which are harsh, nutrient-poor soils derived from rocks of the ocean crust. Edaphic endemics may be unusually vulnerable to climate change for two reasons: because they are trapped on soil "islands" and are thus less able to shift their distributions, and because the effects of a harsh soil may exacerbate the stress of an adverse climate. We will examine this question in two ways: (1) by asking whether Californian serpentine endemics are non-randomly found in more favorable climates, as compared with their closest relatives; (2) by resampling 55-year-old transects in the Klamath Mountains (northern CA - southwestern OR) to ask whether there have been more species disappearances on serpentine at low elevation than on other soils or at higher elevations. Because edaphic endemics contribute substantially to global biodiversity, and because their geographic distributions are unlikely to fit the assumptions of standard climate-based models, this study will fill an important gap in our understanding of the biotic effects of global climate change.