典型草原物种多样性和建群种羊草基因型多样性对植物生长、防御及节肢动物群落的影响研究

Genotypic diversity within dominant species plays a pronounced role in community and ecosystem processes which was similar to species diversity. However, to date, little has been known about either the relative importance of genotypic and species diversity or mechanism by which genotypic and species diversity alter community structure and ecosystem functioning, not to mention the factors which influence them. Nowadays, the typical steppe of Inner Mongolia degraded severely due to climatic change and human disturbance. Leymus chinensis, a dominant species, still had a high abundance in the degraded region. Based on this, we propose two scientific hypotheses in this scheme as follows. Firstly, the effect of genotype diversity of L. chinensis on community productivity and arthropod abundance is higher than that of plant species diversity. Secondly, the diversity effect of L. chinensis in anti-herbivores defenses can be explained by the greater plant growth mechanism. In order to verify these hypotheses, a combined method of independent and crossed diversity would be used to study the effects of species diversity, genotype diversity of L. chinensis and their interaction on plant growth, anti-herbivores defenses and the arthropod community. Our research could be beneficial for understanding the relative importance and mechanism of these two diversities, providing new point of view for predicting the response of typical steppe ecosystem of Inner Mongolia to climatic change, and supplying theoretical direction for rational utilization and protection of seed resources in Inner Mongolia steppe and even the recovery and reestablishment of steppe ecosystem.

建群种基因型多样性对群落结构和系统功能的生态作用可与物种多样性媲美。然而，迄今为止，对群落物种多样性与建群种基因型多样性的生态功能的相对重要性、作用机制及其影响因素仍知之甚少。为此，我们针对受气候变化和人类活动影响，内蒙古典型草原群落退化严重，而建群种羊草在退化区域多度仍较大这一现象提出科学假设：1、羊草基因型多样性效应在提高群落生产力、维持节肢动物多度方面高于群落物种多样性效应；2、羊草在抗取食防御方面的多样性效应可以由高植物生长投入机制所解释。为了验证假说，我们将采用多样性独立与多样性交互相结合的方法，在不同环境条件下研究物种多样性、羊草基因型多样性及它们交互作用在植物生长、防御、节肢动物群落的生态效应的相对重要性，明确效应机制，为更好的预测环境变化下内蒙古典型草原生态系统响应提供新的视角，为内蒙古草原种质资源的合理利用及保护，乃至生态系统的恢复和重建提供理论指导。

建群种基因型多样性对群落结构和系统功能的生态作用可与物种多样性媲美。然而，迄今为止，对群落物种多样性与建群种基因型多样性的生态功能的相对重要性及其影响因素仍知之甚少。受气候变化和人类活动影响，内蒙古典型草原群落退化严重，而建群种羊草在退化区域多度仍较大，针对这一现象，本项目以该区域群落常见种和建群种羊草为研究对象，采用多样性独立与多样性交互相结合的方法，研究了不同环境条件下物种多样性、羊草基因型多样性及交互作用对植物生长、防御、节肢动物群落影响的相对重要性，结果表明：（1）羊草基因型多样性抑制多样性净效应的发挥，且主要抑制互补效应；物种多样性则促进多样性净效应的发挥，主要表现为选择效应对地上生物量的正效应。（2）随着羊草基因型多样性的增加，节肢动物种类、数量与物种多样性间的关系从正相关过渡到负相关；总生物量与节肢动物种类和数量间表现为显著的负相关关系。(3)高生物多样性群落中，节肢动物群落组成更为相似，表明高植物多样性条件下“资源集中化假说”影响了节肢动物群落结构。（4）基因型多样性和干扰强度对土壤动物的种类、数量的影响上存在显著交互作用（P < 0.05）；在留茬10cm处理组中，土壤动物的数量和羊草的基因型多样性呈显著的正相关（P < 0.05），这种现象符合“资源化假说”。（5）羊草基因型数目和氮添加的交互作用对细菌PLFA生物标记含量和真菌/细菌比具有显著影响（P < 0.05）。（6）羊草基因型多样性对冷蒿的生长表现影响显著，当邻居为6基因型时，冷蒿的株高、地上生物量以及总生物量显著低于单基因型和3基因型时的表现(P < 0.05)，且相对竞争强度高于其他两种处理。这与羊草高基因型多样性种群性状变异大，可通过互补作用增强对资源的利用，从而减少空余生态位来抑制冷蒿的生长。这些结果为更好的预测环境变化下内蒙古典型草原生态系统响应提供新的视角，为内蒙古草原种质资源的合理利用及保护，乃至生态系统的恢复和重建提供理论指导。