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Is higher silicon availability increasing the mineralization of organic matter in fen peatlands?

较高的硅利用率是否会增加沼泽泥炭地有机质的矿化？

基本信息

批准号：
327633020
负责人：
Professor Dr. Klaus-Holger Knorr
金额：
--
依托单位：
Institut für Landschaftsökologie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/327633020?language=en
关键词：
higher silicon availability increasing mineralization

项目摘要

The Si cycle is a globally important biogeochemical cycle that directly interacts with major long-term global C sinks. Si availability in ecosystems differs, depending on ecosystem type, bedrock, vegetation and other factors. Recent research has shown that Si availability is also a crucial factor determining organic matter nutrient content, nutrient stoichiometry and litter recalcitrance, especially in grass vegetation. Moreover, Si can affect organic matter decomposition rates by changing the microbial decomposer community in grass systems. Lower nutrient (N, P) content and higher stoichiometric nutrient to phosphorus ratios are well-known to have negative effects on litter decomposition. However, in recent experiments, higher Si content was able to override this effect, with litter from plants exposed to high Si availability degrading faster than controls, even for nutrient-poor litter. The same effect was already confirmed in a field experiment, in which Si decoupled litter decomposition and fungal biomass: While decomposition rates increased, fungal biomass decreased. Consequently, Si exerts an important control on C turnover and on the microbial decomposer community in grass dominated systems. Fen peatlands, providing important carbon stocks and being relevant in global greenhouse gas emissions, are such grass dominated systems with potential impact of Si on C turnover. A preliminary study examining the effect of Si on C-turnover in a fen ecosystem showed enhanced C-turnover and a doubling of soil methane concentration in Si fertilized plots. However, along with the increase in C-turnover a mobilization of P was found. Increasing P availability is well known to also increase C-turnover. The aim of the proposed study is to disentangle the direct effects of Si on C-turnover from the indirect effects via increasing P availability. Our hypothesis are (i) higher Si availability will enhance the mineralization of organic matter (fen peat) to both CO2 and CH4, via (ii) direct Si effects and indirect Si effects by increasing P availability, (iii) the higher mineralization rate of organic matter to both CO2 and CH4 due to increased availability of Si will be achieved rather by bacteria than by fungi, and (iv) increased Si availability will increase P and N availability and uptake into plant biomass and thus lead to more labile litter. Understanding the mechanism how Si is affecting C-turnover in fen systems will contribute significantly to the general understanding of the terrestrial C-turnover.

硅循环是全球重要的地球化学循环，直接与全球主要的长期碳汇相互作用。生态系统中硅的有效性因生态系统类型、基岩、植被和其他因素而异。最近的研究表明，硅的有效性也是决定有机质养分含量、养分化学计量和凋落物分解的关键因素，特别是在草地植被中。此外，硅可以通过改变草地系统中的微生物分解菌群落来影响有机物的分解速率。较低的养分（N，P）含量和较高的化学计量养分与磷的比例是众所周知的凋落物分解的负面影响。然而，在最近的实验中，更高的硅含量是能够推翻这种效果，与垃圾植物暴露于高硅的可用性比对照降解得更快，即使是营养不良的垃圾。同样的效果已经在田间试验中得到证实，其中Si解耦凋落物分解和真菌生物量：而分解速率增加，真菌生物量减少。因此，硅发挥了重要的控制碳周转和微生物分解群落在草为主的系统。汾渭泥炭地是一个以草为主的碳源系统，具有重要的碳储量，与全球温室气体排放密切相关，硅对碳周转具有潜在的影响。初步研究表明，硅对碳周转在沼泽生态系统的影响，提高碳周转和土壤甲烷浓度增加一倍，在硅施肥地块。然而，沿着碳周转率的增加，发现磷的活化。建议的研究的目的是解开直接影响Si对C-营业额的间接影响，通过增加P的可用性。我们的假设是：（1）较高的硅有效性将促进有机质的矿化（ii）直接Si效应和通过增加P有效性的间接Si效应，（iii）由于Si有效性的增加，有机质对CO2和CH 4的矿化速率更高，而不是通过细菌而不是真菌，增加Si的有效性将增加P和N的有效性和植物生物量的吸收，从而导致更不稳定的凋落物。了解硅是如何影响碳周转在沼泽系统的机制将有助于显着的陆地碳周转的一般理解。