SGER: An Analysis of Biotic and Physical Factors in El Nino-Induced Landslides

Reichman等人。98 13668 1997年至1998年的厄尔尼诺(ENSO)事件在整个加州中部沿海地区造成了极高的降雨，并引发了大量的山体滑坡。这些滑坡改变了景观的形状和植被特征。这些滑坡的分布似乎与物理和生物因素的特定组合有关。坡度、母质和土壤水分影响崩塌和泥石流的概率，植被和动物活动的根部特性也影响崩塌和泥石流的发生。该项目将调查滑坡事件的分布，以检查这些生物因素的重要性及其运作机制。在圣巴巴拉附近加州大学自然保护区系统的塞奇威克保护区，人们观察到，几何形状和母质相同的山坡，由于其上出现的植被，似乎显示出不同的坍塌概率。具体地说，沿海鼠尾草灌木丛的地区似乎比周围的草原更有可能展示幻灯片。本项目将记录这一现象，并检查可能导致这种现象的因素。特别是，它将研究树根密度和林下植被发生率的差异，作为引发山体滑坡的潜在原因。它还将测试在鼠尾草灌木区并不常见的地鼠是否通过发展洞穴来增加草原的排水。该项目将有助于了解生物对景观水文学的影响，并为加州这一地区制定保护战略提供重要信息。

Reichman et al. 98 13668 The 1997-1998 El Ni o (ENSO) event has caused extremely high rains throughout central coastal California and these have generated a large number of landslides. These landslides change the shape of the landscape and its vegetational characteristics. The distribution of these landslides appears to be related to a specific combination of physical and biological factors. Slope, parent material and soil water content influence the probability of slumping and mudslides as do the rooting characteristics of vegetation and animal activities. This project would investigate the distribution of landslide events to examine the importance of these biotic factors and the mechanisms by which they operate. On the Sedgwick Reserve in the University of California Natural Reserve system near Santa Barbara, it has been observed that hillslopes with the same geometry and parent materials appear to exhibit different probabilities of slumping due to the vegetation that occurs on them. Specifically, it appears that areas with coastal sage scrub communities are much more likely to exhibit slides than are grasslands that surround them. This project will document this phenomenon and examine the factors that may be causing it. In particular, it will examine differences in root density and the incidence of understory vegetation as potential causal factors driving landslides. It will also test whether gophers, which are not common in sage-scrub areas, increase the drainage of water from grasslands through their development of burrows. This project will contribute to an understanding of biotic influences on landscape hydrology and provide important information for the development of conservation strategies for this region of California.