Estimating function of earthworm communities based on stoichiometry

人类活动正在改变全球生态系统和气候中的氮和磷循环。蚯蚓是改变凋落物分解和土壤物理结构的土壤生态系统工程师。气候变化以及大气氮沉降和施肥导致的氮和磷生态系统循环扰动可能会改变土壤动物的群落结构，特别是蚯蚓，因为氮和磷往往限制陆地生境的养分。我研究了土壤和蚯蚓中的氮和磷含量，并试图估计氮磷平衡扰乱对生态系统水平的影响。蚯蚓的存在大大提高了土壤氮矿化率，因此不仅土壤微生物而且蚯蚓都是氮驱动因素。田间条件下莎莎叶片落叶促进了从根系分泌物开始的土壤微食物网的形成，然后观察到土壤细菌和食菌线虫的变化。最终提高氮的矿化作用。在田间微观条件下，叶片品质影响蚯蚓的生长，体内N:P与日本蚯蚓的生长也存在良好的相关性。外生蚯蚓生长速度快，N:P 低，而内生种类则生长缓慢，N:P 较高。因此，N 和 P 是蚯蚓群落结构的重要决定因素。

Human activities are now changing global nitrogen and phosphorus cycling in ecosystem as well as climate. Earthworms are soil ecosystem engineers modifying litter decomposition and soil physical structures. Climate change and disturbances in ecosystem cycling of N and P due to atmospheric nitrogen deposition and fertilization may change community structure of soil animals, especially, earthworms, because N and P are often limiting nutrients in terrestrial habitat. I studied N and P contents in soil and earthworms and tried to estimate ecosystem level effects of disturbance in NP balance.Soil N mineralization rates were greatly enhanced by the presence of earthworms, thus not only soil microorganisms but also earthworms are nitrogen driver. Defoliation of Sasa leaves in a field condition promoted soil micro-food web starting from root exudation, and then soil bacteria and bactrivorus nematodes were observed to change. Finally nitrogen mineralization was enhanced.Leaf quality affected earthworm growth in a field microcosm condition, and also there was a good correlation between body N:P and growth of Japanese earthworms. Epigeic earthworms had high growth rate and low N:P, and in contrast to this, endogeic species are slow grower and had high N:P. N and P are thus important determinant for community structure of earthworms.