Heske Edward J, Brown James H, Guo Qinfeng
Department of Biology, University of New Mexico, 87131, Albuquerque, NM, USA.
Oecologia. 1993 Oct;95(4):520-524. doi: 10.1007/BF00317436.
Long-term (1977-90) experimental exclusion of three species of kangaroo rats from study plots in the Chihuahuan Desert resulted in significant increases in abundance of a tall annual grass (Aristida adscensionis) and a perennial bunch grass (Eragrostis lehmanniana). This change in the vegetative cover affected use of these plots by several other rodent species and by foraging birds. The mechanism producing this change probably involves a combination of decreased soil disturbance and reduced predation on large-sized seeds when kangaroo rats are absent. Species diversity of summer annual dicots was greater on plots where kangaroo rats were present, as predicted by keystone predator models. However, it is not clear whether this was caused directly by activities of the kangaroo rats or indirectly as a consequence of the increase in grass cover. No experimental effect on species diversity of winter annual dicots was detected. Our study site was located in a natural transition between desert scrub and grassland, where abiotic conditions and the effects of organisms may be particularly influential in determining the structure and composition of vegetation. Under these conditions kangaroo rats have a dramatic effect on plant cover and species composition.
1977年至1990年期间，在奇瓦瓦沙漠的研究区域长期对三种更格卢鼠进行实验性排除，导致一种高大的一年生草本植物（升马唐）和一种多年生丛生草本植物（ Lehmann画眉草）的数量显著增加。植被覆盖的这种变化影响了其他几种啮齿动物和觅食鸟类对这些区域的利用。产生这种变化的机制可能涉及土壤扰动减少和更格卢鼠缺席时大型种子被捕食减少的综合作用。如关键捕食者模型所预测的那样，在有更格卢鼠的区域，夏季一年生双子叶植物的物种多样性更高。然而，目前尚不清楚这是直接由更格卢鼠的活动引起的，还是作为草覆盖增加的结果而间接引起的。未检测到对冬季一年生双子叶植物物种多样性的实验影响。我们的研究地点位于沙漠灌丛和草原之间的自然过渡地带，在那里非生物条件和生物的影响在决定植被的结构和组成方面可能特别具有影响力。在这些条件下，更格卢鼠对植物覆盖和物种组成有显著影响。
