Does shrub invasion indirectly limit grass establishment via seedling herbivory? A test at grassland-shrubland ecotones
Does shrub invasion indirectly limit grass establishment via seedling herbivory? A test at grassland-shrubland ecotones
复制标题
DOI：
10.1111/j.1654-1103.2007.tb02548.x
复制
发表时间：
2007-06-01
影响因子：
2.8
通讯作者：
Peters, Debra P. C.
中科院分区：
文献类型：
--
作者：
Bestelmeyer, Brandon T.;Kalil, N. I.;Peters, Debra P. C.
灌木入侵过渡带是否通过增加哺乳动物幼苗的植食性而间接限制了草地的建立？所在地：奇瓦瓦沙漠，新墨西哥州，美国。方法：我们测试的假设，草食动物相关的死亡率占主导地位的多年生牧草Bouteloua eriopoda的幼苗将是最高的灌木占主导地位的部分草地，灌木交错带。我们测试的假设在两个奇瓦瓦沙漠网站具有相似的灌木入侵模式，但不同的灌木物种，草覆盖，和不同丰度的小型哺乳动物。在每个部位内，我们移植了B。在一年中（仲夏）的时候，他们会自然出现和监测幼苗命运的草类为主，中间，灌木为主的位置复制交错带。我们估计人口规模/活动的推定的小型哺乳动物herbivores.Results：幼苗被杀死的哺乳动物在灌木丛中的数量比在草地或中间交错带的位置，在该网站与大草食动物的数量。在植食动物数量较少的地点，大部分幼苗在中间过渡带位置死亡。草食动物的丰富模式没有平行模式的幼苗草食动物的交错带或sites.Conclusions：幼苗草食是一个重要的过程，并与植被组成，但机制的关系还不清楚。我们推测，小哺乳动物觅食行为的变化可能有助于幼苗草食模式。在奇瓦瓦沙漠的恢复策略需要考虑本地食草动物的丰度和/或行为。
Question: Does shrub invasion at ecotones indirectly limit grass establishment by increasing mammalian seedling herbivory?Location: Chihuahuan Desert, New Mexico, USA.Methods: We tested the hypothesis that herbivore-related mortality of seedlings of the dominant perennial grass Bouteloua eriopoda would be highest in shrub-dominated portions of grassland-shrubland ecotones. We tested the hypothesis in two Chihuahuan Desert sites featuring similar shrub encroachment patterns but different shrub species, grass cover, and different abundances of small mammals. Within each site we transplanted B. eriopoda seedlings to grass-dominated, middle, and shrub-dominated positions of replicate ecotones during the time of year (mid-summer) when they would naturally appear and monitored seedling fates. We estimated population size/activity of putative small mammal herbivores.Results: Seedlings were killed by mammals in greater numbers in shrubland than in grassland or middle ecotone positions at the site with large herbivore numbers. At the site with low herbivore numbers, most seedlings were killed in middle ecotone positions. The abundance patterns of herbivores did not parallel patterns of seedling herbivory across the ecotones or between sites.Conclusions: Seedling herbivory is an important process and is related to vegetation composition, but the mechanisms underlying the relationship are not clear. We speculate that variation in small mammal foraging behavior may contribute to seedling herbivory patterns. Restoration strategies in the Chihuahuan Desert need to account for the abundance and/or behavior of native herbivores.