Role of tussock morphology in providing protection from grazing for neighbouring palatable plants in a semi-arid Mongolian rangeland
Role of tussock morphology in providing protection from grazing for neighbouring palatable plants in a semi-arid Mongolian rangeland
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DOI：
10.1080/17550874.2014.926406
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发表时间：
2015-03
影响因子：
1.5
通讯作者：
Asuka Koyama;Y. Yoshihara;U. Jamsran;T. Okuro
中科院分区：
文献类型：
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作者：
Asuka Koyama;Y. Yoshihara;U. Jamsran;T. Okuro
背景：牧场上的美味植物可能由于周围存在不那么美味的植物而免受食草动物的放牧。在重度放牧条件下，恩宠物种对适食物种的保护作用往往会减弱，但其潜在机制——保护作用的减弱与放牧对恩宠物种的损害之间的关系尚不清楚。目的：阐明在重度放牧条件下，一种不那么美味的柞蚕草（Achnatherum splendens）对周围美味物种的保护是否会减少，重点研究放牧对柞蚕形态的影响。方法：在蒙古草原轻、重度放牧条件下，对3个芨芨草微生境（草场内、草场旁和草场外）的芨芨草形态特征、甘美禾草类植物密度和放牧危害进行了测定。结果：在重度放牧条件下，芨芨草的基面积和秆高较小，秆密度较大。粪巢内和粪巢内适口禾草的密度均等于或低于粪巢外，但粪巢内的放牧损害有所减少。此外，植丛内的植丛数与芨芨草秆密度呈负相关，这可能与植丛内的空间竞争有关。结论：草草正相互作用的崩溃是由于放牧引起的形态变化导致邻近有益植物数量的减少。
Background: Palatable plants in rangelands may be protected from herbivore grazing by the presence of less palatable neighbouring plants. The protective role of benefactor species on palatable species often collapses under heavy grazing, but the underlying mechanism—the relationship between the reduced protective role and grazing damage to benefactor species—remains unclear. Aims: To clarify whether the protection of surrounding palatable species conferred by a less palatable tussock grass (Achnatherum splendens) is reduced under heavy grazing, focusing on the changes to tussock morphology caused by grazing. Methods: In the Mongolian steppe, we measured the morphological traits of A. splendens tussocks, plant density of palatable graminoids and grazing damage in three A. splendens microhabitats (inside, adjacent to, and outside tussocks) under light and heavy grazing areas. Results: A. splendens tussocks had smaller basal area and culm height, and greater culm density under heavy grazing. The densities of palatable graminoids adjacent to and inside tussocks were equal to or lower than those outside, but grazing damage decreased inside tussocks. Additionally, plant establishment inside tussocks was negatively related to A. splendens culm density, probably owing to competition for space within the tussocks. Conclusions: Our results indicate that the collapse of positive grass–grass interactions results from the decline in neighbouring benefactor plants through the morphological changes caused by grazing.