Contrasting Effects of Long-Term Grazing and Clipping on Plant Morphological Plasticity: Evidence from a Rhizomatous Grass.
Contrasting Effects of Long-Term Grazing and Clipping on Plant Morphological Plasticity: Evidence from a Rhizomatous Grass.
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DOI：
10.1371/journal.pone.0141055
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Ren W
中科院分区：
文献类型：
--
作者：
Li X;Wu Z;Liu Z;Hou X;Badgery W;Guo H;Zhao Q;Hu N;Duan J;Ren W
了解植物形态可塑性的机制，以响应放牧和修剪的半干旱草地，可以提供洞察干扰引起的草地生产力下降的过程。在最近的研究中，有两个假说存在争议：1）放牧回避; 2）生长限制机制的形态可塑性，以响应脱叶。然而，实验证据提出的记忆反应放牧和修剪的植物一直很少报道。本文报道了两个实验，分别在现场和在受控环境中测试这些假设。研究了长期刈割和放牧对羊草（Leymus chinensis（Trin.）Tzvelev是内蒙古典型草原的优势种。这些实验有四个主要发现。(i)大部分的表型性状都与L.在长期的野外刈割和放牧条件下，中华绒螯蟹趋于显著的退化。(ii)在消除环境变异的水培试验中，放牧和不放牧对形态可塑性的显著响应都得以维持，但在L.中华绒螯蟹个体大小性状进行扦插比较。(iii)L.结果表明，在控制环境下，羊草各性状均显著低于田间条件下，表明植物对长期放牧具有部分和轻微的记忆效应。(iv)各种表型性状的异速生长，叶和茎的分配与脱叶诱导的植物大小的变化之间的显着权衡，这是保持在放牧条件下的水培控制环境实验。综上所述，我们的研究结果表明，形态可塑性L。人工刈割和放牧对羊草的影响不同。长期放牧草地植物个体的小型化可能反映了植物为适应大型草食动物长期放牧而保留的矮小记忆特征。
Understanding the mechanism of plant morphological plasticity in response to grazing and clipping of semiarid grassland can provide insight into the process of disturbance-induced decline in grassland productivity. In recent studies there has been controversy regarding two hypotheses: 1) grazing avoidance; and 2) growth limiting mechanisms of morphological plasticity in response to defoliation. However, the experimental evidence presented for the memory response to grazing and clipping of plants has been poorly reported. This paper reports on two experiments that tested these hypotheses in field and in a controlled environment, respectively. We examined the effects of long-term clipping and grazing on the functional traits and their plasticity for Leymus chinensis (Trin.) Tzvelev (the dominate species) in the typical-steppe grassland of Inner Mongolia, China. There were four main findings from these experiments. (i) The majority of phenotypic traits of L. chinensis tended to significantly miniaturize in response to long-term field clipping and grazing. (ii) The significant response of morphological plasticity with and without grazing was maintained in a hydroponic experiment designed to remove environmental variability, but there was no significant difference in L. chinensis individual size traits for the clipping comparison. (iii) Plasticity indexes of L. chinensis traits in a controlled environment were significantly lower than under field conditions indicating that plants had partial and slight memory effect to long-term grazing. (iv) The allometry of various phenotypic traits, indicated significant trade-offs between leaf and stem allocation with variations in plant size induced by defoliation, which were maintained only under grazing in the hydroponic controlled environment experiment. Taken together, our findings suggest that the morphological plasticity of L. chinensis induced by artificial clipping was different with that by livestock grazing. The miniaturization of plant size in long-term grazed grassland may reflect retained characteristics of dwarf memory for adaptation to long-term grazing by large herbivores.