Gao Y, Wang D, Xing F, Liu J, Wang L
Institute of Grassland Science, Northeast Normal University, Key Laboratory of Vegetation Ecology, Ministry of Education, Key Laboratory of Ecological Restoration and Ecosystem Management of Jilin Province, Changchun, China.
Plant Biol (Stuttg). 2014 Jul;16(4):774-82. doi: 10.1111/plb.12122. Epub 2013 Nov 14.
Previous lines of investigation assuming potential advantage of clonal integration generally have neglected its plasticity in complex heterogeneous environments. Clonal plants adaptively respond to abiotic heterogeneity (patchy resource distribution) and herbivory-induced heterogeneity (within-clone heterogeneity in ramet performance), but to date little is known about how resource heterogeneity and simulated herbivory jointly affect the overall performance of clones. Partial damage within a clone caused by herbivory might create herbivory-induced heterogeneity in a resource-homogeneous environment, and might also decrease or increase the extent of heterogeneity under resource-heterogeneous conditions. We conducted a greenhouse experiment in which target-ramets of Leymus chinensis segments within homogeneous or heterogeneous nutrient treatments were subject to clipping (0% or 75% shoot removal). In homogeneous environments with high (9:9) nutrient availability, ramet biomass of L. chinensis with intact or severed rhizomes is 0.70 or 0.69 g. Conversely, target-ramet biomass with intact rhizomes is obviously lower than that of the severed target-ramets in the homogeneous environments with medium (5:5) and low (1:1) nutrient availability. High resource availability and the presence of herbivory can alleviate negative effects of rhizome connection under homogeneous conditions, by providing copious resource or creating herbivory-induced heterogeneity respectively. Herbivory tolerance of clonal fragments with connected rhizomes was higher than that of fragments with severed rhizomes under heterogeneous conditions. These findings confirmed the unconditional advantage of clonal integration on reproduction under the combined influence of resource heterogeneity and simulated herbivory. Moreover, our results made clear the synergistically interactive effects of resource heterogeneity and simulated herbivory on costs and benefits of clonal integration. This will undoubtedly advance our understanding on the plasticity of clonal integration under complex environmental conditions.
以往关于克隆整合潜在优势的研究思路通常忽视了其在复杂异质环境中的可塑性。克隆植物能对非生物异质性（斑块状资源分布）和食草动物诱导的异质性（分株表现的克隆内异质性）做出适应性反应，但迄今为止，对于资源异质性和模拟食草作用如何共同影响克隆的整体表现知之甚少。食草动物造成的克隆内部分损伤可能会在资源均匀的环境中产生食草动物诱导的异质性，也可能会在资源异质条件下降低或增加异质性程度。我们进行了一项温室实验，将羊草切段的目标分株置于均匀或异质养分处理中，并进行刈割（去除0%或75%的地上部分）。在养分有效性高（9:9）的均匀环境中，具有完整或切断根状茎的羊草分株生物量分别为0.70克或0.69克。相反，在养分有效性中等（5:5）和低（1:1）的均匀环境中，具有完整根状茎的目标分株生物量明显低于切断根状茎的目标分株。高资源有效性和食草作用的存在，在均匀条件下分别通过提供丰富资源或产生食草动物诱导的异质性，可减轻根状茎连接的负面影响。在异质条件下，具有相连根状茎的克隆片段的食草耐受性高于根状茎切断的片段。这些发现证实了在资源异质性和模拟食草作用的联合影响下，克隆整合在繁殖方面具有无条件优势。此外，我们的结果明确了资源异质性和模拟食草作用对克隆整合成本和效益的协同交互作用。这无疑将推进我们对复杂环境条件下克隆整合可塑性的理解。
