栓皮栎林地土壤有机碳增汇的生态化学计量学特征

The more stable fraction pool of soil organic matter (heavy fraction organic matter, soil particle size <0.4 mm) has more nitrogen, phosphorus and sulphur (N, P, S) per unit of carbon (C) than the plant material from which it originates and has near constant ratios of C:N:P:S. Consequently, we hypothesised that the sequestration of C-rich crop residue material into the soil could be improved by adding supplementary nutrients to the residues based on these ratios. This study will use soil C, N, P and S ecological stoichiometry of soil stable fraction pool of soil organic matter as the entry points to explore the mechanism of increasing soil organic carbon sinks in Henan Quercus variabilis forests. There are four objectives in this study: 1) the C:N:P:S stoichiometric ratios in stable fraction pool of soil organic matter(<0.4 mm) of Henan Quercus variabilis forests will be determined and whether it following some Redfield ratio. 2) soil cultivation experiment of forest litter and field pilot of soil organic carbon will be done to reveal the relationship between C:N:P:S stoichiometric ratios in stable fraction pool and soil carbon sequestration during the process of cultivation periods. 3) How to adjust soil N, P and S element contents in Henan Quercus variabilis forests, and how the soil stable fraction pool changes after soil N, P and S contents were adjusted; 4) how to regulate the application of slow-release fertilizer technology to adjust soil nutrient contents, making it to build an ecological driving force for forest soil carbon sequestration. This will facilitate human understanding and control of soil carbon cycle, provide new ideas to mitigate the greenhouse effect, to solve a series of ecological and environmental problems of great significance.

森林土壤稳定性有机质组分(重组部分，粒径<0.4 mm)与森林凋落物均具有较稳定的碳-养分(氮、磷、硫等)化学计量学特征。森林凋落物碳含量较高，养分物质(氮、磷、硫)含量较低。如果按稳定性有机质组分碳-养分比率，增加土壤氮、磷、硫含量，有助于凋落物向稳定性有机质的转化。本项目以此为切入点，探索栓皮栎林地土壤稳定性有机质组分中碳-养分物质生态化学计量学特征的土壤碳增汇机制。研究目标：1)土壤稳定性有机质组分碳-养分化学计量比率对凋落物分解和有机碳积累的影响机制；2)栓皮栎林地土壤稳定性有机质组分中碳、氮、磷元素是否遵循某种Redfield比率；3)现实栓皮栎林地土壤的N、P、S元素含量调整后，土壤有机碳含量有怎样的动态；4)怎样应用缓释肥技术来调控现实林地养分含量，使之成为森林土壤碳增汇的生态驱动力。本研究将有利于人类了解和控制土壤碳循环，对解决一系列的生态环境问题具有重要意义。

本项目以生态化学计量为切入点，探索栓皮栎林地土壤有机碳增汇的生态化学计量学特征。研究内容有四：栓皮栎林地土壤稳定性有机质组分(粒径<4 mm)的碳-养分(氮、磷、硫)化学计量比率统一值的确定；土壤添加氮磷硫元素对稳定性有机质组分(粒径<4 mm)碳含量的影响的控制实验；栓皮栎林地土壤碳增汇的田间中试；河南省森林土壤碳汇的生态化学计量比率范围。结果：(1) 栓皮栎林地土壤稳定性有机质组分(粒径<4 mm)中C∶N∶P∶S化学计量比例关系为10000/828/201/139，栓皮栎林地土壤中存在有Redfield 比率特征；(2) 栓皮栎林地土壤碳-养分(氮、磷、硫)化学计量比率调整后，重组碳含量随外源氮、磷和硫元素添加量的增加而增加，碳与氮、硫的相关性高于碳与磷的相关性；(3) 田间自然状态与实验室控制状态下，栓皮栎林地土壤调整N、P、S等元素后，土壤碳库各组分碳含量与差异较大；(4)实验室和田间实验表明，外源养分添加提高了凋落物的腐殖质化率。无养分添加时腐殖质化率为1.9%～4.9%。添加1倍养分后为6.8～14.7%，添加2倍养分后为12.6～19.8%。调整C∶N∶P等主要元素的化学计量，使之成为森林土壤有机碳固定的生态驱动力。这将有利于人类了解甚至控制全球碳循环，为减缓温室效应提供新思路，对解决一系列的生态环境问题具有重要的现实意义。