水保所知识产出(1956---)知识库

To explore carbon (C), nitrogen (N), and phosphorus (P) dynamics during leaf litter decomposition, we inves-
tigated the temporal variability of soil microbial biomass and associated soil enzyme activities. Our 342-day leaf
litter (Quercus wutaishanica) decomposition experiment at the Loess Plateau (China) sheds light on how soil
microorganisms – mainly the soil microbial biomass C, N, P, and soil enzyme activities – maintain element
homeostasis of C, N, and P by producing soil enzymes during various phases of litter decomposition. Overall, the
highest soil enzyme activities were measured in summer, whereas soil microbial biomass carbon (MBC) and soil
microbial biomass nitrogen (MBN) were highest in winter. Soil water content and soil temperature had signif-
icant effects on soil enzyme activities and stoichiometry. The results indicate that the stoichiometry of extra-
cellular enzyme activities (lnBG:lnNAG:lnAP) changes significantly between individual stages of litter
decomposition. The resources available for microorganisms were restricted by C and P, while P limitation
progressively decelerated during decomposition and C limitation was enhanced at the latest stage. Strong pos-
itive correlations between ecological indicators of microbial element limitation and soil enzyme activities
indicated that microbes allocate C and nutrients towards soil enzyme production to mine for scarce nutrients.
This adaptation strategy enabled the soil microorganisms to maintain element homeostasis. Soil MBC, MBN, soil
microbial biomass phosphorus (MBP), MBC:MBN, MBC:MBP, and MBN:MBP rarely showed significant correla-
tions with soil or leaf litter C, N, P, C:N, C:P, and N:P. This suggests no resource dependency of microbial element
composition but supports the concept of element homeostasis of soil microorganisms. Besides compensating for
element imbalances by adjusting soil enzyme production, the microorganisms also adjusted element use effi-
ciencies such as C use efficiency. We conclude that the maintenance of element homeostasis by soil microor-
ganisms induces a tight co-regulation of enzymes involved in covering their C and nutrient supply during
successive litter degradation.