Martinsen Gregory D, Cushman J Hall, Whitham Thomas G
Department of Biological Sciences, Northern Arizona University, 86011, Flagstaff, AZ, USA.
Oecologia. 1990 May;83(1):132-138. doi: 10.1007/BF00324644.
We examined the impact of pocket gopher disturbances on the dynamics of a shortgrass prairie community. Through their burrowing activity, pocket gophers (Thomomys bottae) cast up mounds of soil which both kill existing vegetation and create sites for colonization by competitively-inferior plant species. Three major patterns emerge from these disturbances: First, we show that 10 of the most common herbaceous perennial dicots benefit from pocket gopher disturbance; that is, a greater proportion of seedlings are found in the open space created by pocket gopher disturbance than would be expected based on the availability of disturbed habitat. Additionally, these seedlings exhibited higher growth rates than adjacent seedlings of the same species growing in undisturbed habitat. Second, we tested two predictions of the Intermediate Disturbance Hypothesis and found that species diversity was greatest for plots characterized by disturbances of intermediate age. However, we did not detect significant differences in diversity between plots characterized by intermediate and high levels of disturbance, indicating that many species are adapted to or at least tolerant of high levels of disturbance. Third, we noted that the abundance of grasses decreased with increasing disturbance, while the abundance of dicots increased with increasing disturbance.
我们研究了囊鼠扰动对矮草草原群落动态的影响。囊鼠（汤氏囊鼠）通过挖掘活动堆积起土丘，这些土丘既会杀死现有的植被，又会为竞争力较弱的植物物种创造定居场所。这些扰动呈现出三种主要模式：第一，我们发现10种最常见的多年生草本双子叶植物受益于囊鼠扰动；也就是说，在囊鼠扰动创造的空地上发现的幼苗比例高于根据受干扰栖息地的可利用性所预期的比例。此外，这些幼苗的生长速度比生长在未受干扰栖息地的同物种相邻幼苗更高。第二，我们检验了中度干扰假说的两个预测，发现对于以中等年龄扰动为特征的样地，物种多样性最高。然而，我们没有检测到以中等和高水平干扰为特征的样地之间在多样性上的显著差异，这表明许多物种适应或至少耐受高水平的干扰。第三，我们注意到随着干扰增加，草本植物的丰度下降，而双子叶植物的丰度随着干扰增加而上升。
