Influence of soil fauna on litter decomposition

在过去20年的几十次实验中测量了凋落物分解率后，我得出结论（FEM）： 1)我们对凋落物分解率的变化解释了一些现象的期望是不正确的，比如丰富的地方变得更丰富，或者在砍伐或施肥的森林中有更高的N可用性，在我们更好地了解分解过程本身之前，我们将不会在测量、建模或理解分解率方面取得进一步的进展；尤其是分解的后期阶段。我们对凋落物分解率的估计大多来自于排除了土壤大型动物的研究，因此可能严重错误地反映了长期腐烂率。土壤动物消耗的大部分凋落物都是通过肠道而不是完全分解的；因此，在准确预测和模拟凋落物分解之前，了解土壤动物粪便物质的命运是必要的。稳定同位素分析技术的最新发展使我们能够解决这个以前难以解决的问题。在拟议的研究中，我将1)在一系列立地条件下和不同树种下描述森林土壤动物群落和养分有效性；2)确定土壤动物和微生物群落与养分有效性之间的关系；3确定土壤动物和微生物群落与区域气候等广泛因素的关系更密切，还是与土壤质地、土壤类型、坡位、坡向、坡向等基本立地因素的关系更密切。4)使用稳定同位素分析来确定凋落物碳在土壤食物网中移动时的命运；5)比较蚁巢与周围森林地面的C、N和P矿化率，以更好地代表不列颠哥伦比亚省干旱森林生态系统的养分循环

Having measured litter decomposition rates in dozens of experiments over the last 20 years, I have concluded (FEM) that 1) our expectations that changes in rates of litter decomposition explain several phenomena such as rich sites getting richer, or higher N availability in clearcut or fertilized forests are incorrect, and that we will make no further progress in measuring, modeling or understanding decomposition rates until we better understand the process itself, in particular the later stages of decomposition.  Most of our estimates of litter decomposition rates have been derived from studies in which soil macrofauna have been excluded, and thus may seriously misrepresent long-term decay rates.  Most of the litter consumed by soil fauna is passed through the gut rather than completely decomposed; thus understanding of the fate of fecal material of soil fauna is necessary before we can accurately predict and model litter decomposition. Recent development of stable isotope analysis techniques allows us to address this previously intractable problem.   In the proposed research, I will 1) characterize soil faunal communities and nutrient availability in forests across a range of site conditions and under different tree species, 2) determine relationships between soil faunal and microbial communities and nutrient availability, 3 determine whether soil faunal and microbial communities are more closely correlated to broad factors such as regional climate, or to fundamental site factors such as soil texture, soil type, slope position, aspect, or to the nature of the trees and other vegetation on the site, 4) use stable isotope analysis to determine the fate of litter carbon as it moves through the soil food web, and 5) compare rates of C, N and P mineralization in ant nests compared with surrounding forest floor to better represent nutrient cycling in dry forest ecosystems in B.C.