森林土壤激发效应对土壤有机碳库平衡的影响

This study will use ecological stoichiometry as the entry points to explore the mechanism of the priming effect of in Henan typical forest soils, and to achieve the maximum target of forest soil carbon sink. Forest soil carbon storage is controlled by the principle of mass conservation, and by the nitrogen, phosphorus and other key nutrients supply, and the control of priming effect is the key to forest soil carbon sinks. There are four parts in this study. The first, is that the stoichiometric ratio of Henan’s typical forest soil and microbial organisms will be determined whether following some Redfield ratio in this study. The second is that cultivation experiment of soil microbial and field pilot of soil organic will be done to reveal the relationship mechanism between microbial biomass and soil carbon during the process of soil priming effect. Using C:N:P stoichiometric ratio to analyze the relationship between forest soil carbon cycle balance and constraints. The third, is to establish the range of stoichiometric ratio which can maximize forest soil carbon sink function. Using the C:N:P ratio of ecological parameters which is easy to get to predict the balance trend of soil carbon pools, and to estimate soil carbon sequestration potential; How to adjust the C:N:P stoichiometry ratio to built a ecological driving force for the forest soil organic carbon sequestration. This will help humans to understand and even control the golbal carbon cycle, to reduce the greenhouse effect and to provide new ideas for solving a series of environmental problems which has important pratical significance.

本研究以生态化学计量为切入点，探索河南森林土壤激发效应的发生机制，进而增加森林土壤碳汇功能。研究内容有四：一、森林土壤、土壤微生物有机体碳、氮、磷等主要元素化学计量比率是否遵循某种Redfield比率；二、土壤微生物是否按照自身的化学计量比率从土壤中获取所需要的能源和养分；三、用C∶N∶P化学计量比率分析森林土壤碳循环的平衡与制约关系，揭示土壤激发效应过程中，外源碳、微生物生物量与土壤碳之间的关系机制；四、建立河南省森林土壤碳汇功能最大化的化学计量比率指标范围；利用C∶N∶P比这样易获取的生态参数预测土壤碳库的平衡趋势，估算土壤碳汇潜力，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。

人类不合理的生产活动已导致 CO2 等温室气体的不断增加，业已产生了气候变化等严重的生态环境问题，引起了世界各国的重视。要降低CO2 浓度，减弱全球气候变化，重要的手段之一是利用植物光合作用吸收CO2，合成有机物，进入土壤，形成土壤有机碳。即提高土壤碳汇的功能。本团队自项目启动以来，一方面严格地执行国家基金委批复的项目计划书，另一方面又结合自己前期的研究基础，以河南省森林土壤、土壤微生物有机体碳、氮、磷等主要元素化学计量学对象，以其比率是否遵循某种Redfield比率、土壤微生物是否按照自身的化学计量比率从土壤中获取所需要的能源和养分为切入点，用C∶N∶P化学计量比率分析森林土壤碳循环的平衡与制约关系，揭示土壤激发效应过程中，外源碳、微生物生物量与土壤碳之间的关系机制，进而调整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。我们研究的主要结论如下：(1)河南省森林森林土壤、微生物生物量化学计量遵循一定的比率关系，我们在太行山林区、伏牛山林区和大别山林区的采样结果表明森林土壤C∶N∶P 在比率大致为145:11:1，土壤微生物比率约为70:7:1.1，即遵循某种Redfield 比率；（2）初步探明了土壤微生物激发效应的机制问题，探明化学计量比率对典型森林土壤有机碳分解的影响。实验室控制实验表明：外源氮、磷等养分的添加有利于土壤有机碳的累积。无养分添加时，土壤有机碳含量变化趋势为初期降低，后期缓慢增高，整个培育期内有机碳含量增加了1.7-7.4 g·kg-1；添加1倍养分后，土壤有机碳含量持续增高，整个培育期增加了5.9-22.3 g·kg-1；2倍养分添加后，有机碳增量了11.1-30.1 g·kg-1；（3）增加森林土壤碳汇功能的植被格局的设计，我们认为要增加森林土壤有机碳汇功能、增加土壤有机碳储量，首先要调整植被种类，发展混交林，培育乔灌草相结合的营林模式，同时增施外源氮磷元素，促进有机碳的土壤积累。