PDF(Pubmed)
Abstract：
Symbiotic nitrogen (N) fixation (SNF) by legumes and their rhizobial partners is one of the most important sources of bioavailable N to terrestrial ecosystems. While most work on the regulation of SNF has focussed on abiotic drivers such as light, water and soil nutrients, the diversity of rhizobia with which individual legume partners may play an important but under-recognized role in regulating N inputs from SNF. By experimentally manipulating the diversity of rhizobia available to legumes, we demonstrate that rhizobial diversity can increase average SNF rates by more than 90%, and that high rhizobial diversity can induce increased SNF even under conditions of high soil N fertilization. However, the effects of rhizobial diversity, the conditions under which diversity effects were the strongest, and the likely mechanisms driving these diversity effects differed between the two legume species we assessed. These results provide evidence that biodiversity-ecosystem function relationships can occur at the scales of an individual plant and that the effects of rhizobial diversity may be as important as long-established abiotic factors, such as N availability, in driving terrestrial N inputs via SNF.
摘要：
豆科植物及其根瘤菌伙伴的共生固氮（SNF）是陆地生态系统生物可利用氮的最重要来源之一。虽然大多数关于SNF监管的工作都集中在非生物驱动因素上，如光，水和土壤养分，根瘤菌的多样性，单个豆科植物伙伴可能在调节SNF的N输入方面发挥重要但未得到充分认可的作用。通过实验操纵豆科植物根瘤菌的多样性，我们证明根瘤菌多样性可以使平均SNF率提高90%以上，即使在高土壤氮肥条件下，高根瘤菌多样性也会导致SNF增加。然而,根瘤菌多样性的影响，多样性效应最强的条件，驱动这些多样性效应的可能机制在我们评估的两种豆科植物物种之间有所不同。这些结果提供了证据，表明生物多样性-生态系统功能关系可以在单个植物的尺度上发生，根瘤菌多样性的影响可能与长期建立的非生物因素一样重要。例如N可用性，通过SNF驱动地面N输入。
