Dynamics of Mojave Desert Shrub Assemblages in the Panamint Mountains, California
Dynamics of Mojave Desert Shrub Assemblages in the Panamint Mountains, California
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加利福尼亚州帕纳明特山脉莫哈韦沙漠灌木群落的动态
DOI：
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发表时间：
1987
期刊：
影响因子：
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通讯作者：
R. Turner
中科院分区：
文献类型：
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作者：
R. Webb;J. Steiger;R. Turner
我们对莫哈韦沙漠Panamint山脉的灌木群落进行了研究，以确定干扰后的植被变化是否可以根据现代演替理论来描述为演替。我们发现，在各种受干扰和未受干扰的地点上，变化的速度是干扰的类型和年龄的函数。现代泥石流堆积物被物种组成与周围不同的灌木组合、较老的泥石流堆积物和其他地貌稳定的表面所殖民。人类干扰地点的定殖性很强，但物种组成与干扰前的物种组成不同。在Grayia-Lycium组合中，Grayia Spinosa相对较快地重新确立了对殖民者的优势。在通常在较老的地貌表面发现的Coleogyne组合中，物种组成差异持续的时间要长得多，这取决于初始干扰的严重程度。由Coleogyne ramosis sima主导的极稳定的组合出现在最古老、干扰最少的表面。干扰地之间物种组成的变异大于未干扰地和地貌稳定地之间的变异，符合趋同演替规律。沙漠演替的模型应考虑以下几个因素：(1)定居在很大程度上取决于干扰的严重程度和残留的生物成分；(2)恢复的时间跨度可能比过去的气候和地貌稳定时期更长；(3)定居物种的生活史策略可能有相当大的范围。
We studied shrub communities in the Panamint Mountains of the Mojave Desert to determine whether vegetational changes after disturbance can be characterized as succession according to modern successional theory. We found, on a variety of disturbed and undisturbed sites, that the rate of change was a function of the type and age of disturbance. Recent debris—flow deposits were colonized by shrub assemblages of different species composition than those on the surrounding, older debris—flow deposits and other geomorphically stable surfaces. Colonization of human—disturbed sites was highly variable, but species compositions were different from the predisturbance species composition. In Grayia—Lycium assemblages, Grayia spinosa reasserted its dominance over colonizers relatively quickly. In Coleogyne assemblages, typically found on older geomorphic surfaces, species composition differences persisted considerably longer, depending on the severity of the initial disturbance. Extremely stable assemblages, dominated by Coleogyne ramosissima, occurred on the oldest, least disturbed surfaces. The variability of species composition among disturbed sites was greater than the variability among undisturbed and geomorphically stable sites, in accord with convergent succession. Models of desert succession should consider several factors: (1) colonization is dependent largely on the severity of disturbances and residual biotic components; (2) the time span for recovery may be longer than past periods of climatic and geomorphic stability; and (3) colonizing species may have considerable range in their life—history strategies.