八大公山亚热带常绿落叶阔叶混交林土壤碳氮空间变异及影响因素研究

发布时间：2018-02-24 02:35

本文关键词： 亚热带森林土壤有机碳空间格局环境因子碳稳定性同位素　出处：《中国科学院研究生院(武汉植物园)》2016年博士论文　论文类型：学位论文

【摘要】：土壤作为陆地生态系统最大的碳库和氮库,其微小波动也会对全球碳氮循环过程造成深远影响。土壤固碳被认为是缓和气候变化最重要的途径之一。因为土壤碳氮具有很强的空间变异特征,所以预测土壤碳氮循环对全球变化的响应及评估土壤固碳的能力仍具有很大的不确定性。在局域尺度上开展森林土壤碳氮空间变异及影响因素的研究能够为准确预测森林土壤碳库、氮库对全球变化的响应提供更加可靠的信息,也能有效加深我们对区域土壤碳氮循环机制的理解。同时,研究不同植物群落类型对土壤碳氮含量及空间分布的影响及其可能机制,对制定合理的森林管理措施并缓解气候变化也具有一定的理论参考价值。本研究以湖南八大公山25 ha森林生物多样性监测样地土壤为研究对象,在大量采样(n=972)的基础上,利用半方差分析和方差分解等分析方法对该区土壤有机碳(SOC)和总氮(TN)含量以及土壤δ13C的空间变异及影响因素进行研究；在样地内选取两种不同群落类型,对比分析了不同植物群落类型(小花木荷群落Schima parviflora和亮叶水青冈群落Fagus lucida)对SOC和TN空间分布的影响,初步探讨了其可能的影响机制。主要结果如下：八大公山25 ha样地土壤表层及亚表层SOC和TN均呈中等程度的空间自相关,但表层土壤空间自相关强度要低于亚表层土壤。SOC和TN在2m尺度以下具有较强的空间变异,推测与微地形及土壤微生物密切相关的微环境因子对SOC和TN在该尺度上的空间变异起着重要作用。土壤因子是影响八大公山SOC和TN空间变异的主要因素,土壤pH、有效磷及粘粒含量与SOC含量具有显著的相关关系。植被因子对SOC含量的影响表现出一定的尺度效应,在20 m的尺度上对土壤碳含量的影响远大于5 m和10 m尺度。虽然地形因子对SOC和TN的解释量较小,但Mantel's test的结果仍显示地形与SOC含量呈显著相关。空间结构因子作为各种尺度空间过程的集合,对SOC和TN的空间变异具有重要影响。各类因子间具有复杂的交互作用。八大公山25 ha样地土壤δ13C值变化范围较小,表层土壤813C值显著低于亚表层土壤,且均表现为中等程度的空间自相关。土壤613C值在2 m尺度以下仍具有一定的变异性,可能主要是由微生物利用SOC导致的同位素分馏或其他空间过程引起的。土壤、植被和地形因子对土壤δ13C值变异的总解释量在表层和亚表层间大致相当,但空间结构因子对亚表层土壤δ13C的解释力明显高于表层土壤。表明亚表层土壤碳稳定同位素组成更易受各种空间过程的影响。植被因子的解释力微小,说明在本研究中所涉及的植被属性在不同样点间的差异并不足以对土壤碳稳定同位素的组成造成显著的影响。土壤因子则可能通过调控微生物的同位素分馏影响土壤δ13C的空间变异。地形因子对土壤813C值空间变异的解释量主要通过与空间结构因子的共同作用实现。植被群落类型对SOC和TN的空间分布具有显著影响。对于SOC和TN含量,不同群落类型间的差异主要表现在表层土壤(0-10 cm),推测这与凋落物来源的碳和该区强烈的淋溶作用有关。对于土壤碳氮储量,差异则主要表现在深层土壤(30-60 cm)。群落类型对土壤C/N无显著影响,C/N在相同土壤深度条件下趋于稳定,反映了该区土壤碳氮间的紧密关系。不同群落类型间土壤δ13C值具有显著差异,可能是由群落间地上凋落物和细根δ13C值的差异引起的。
[Abstract]:As the soil carbon and nitrogen pool the largest terrestrial ecosystem, the small fluctuations will cause a profound impact on the global carbon and nitrogen cycling. Soil carbon sequestration is considered to be one of the most important ways to mitigate climate change. Because of the spatial variability of soil carbon and nitrogen is very strong, so the prediction of soil carbon and nitrogen cycle of global change the response and evaluation of soil carbon sequestration capacity still has a lot of uncertainty. The development space of soil carbon and nitrogen in forest variation and influencing factors research to accurately predict the forest soil carbon pool in the local scale, nitrogen pool to global change in response to provide more reliable information, but also can deepen our understanding of carbon the nitrogen cycle mechanism of regional soil. At the same time, different plant community types on soil carbon and nitrogen contents and spatial distribution and the possible mechanism of forest management measures, reasonable and slow. Climate change also has a certain reference value. This study takes Hunan Badagong mountain biological diversity monitoring ha 25 forest soil samples as the research object, in a large number of sampling (n=972) on the basis of soil organic carbon in this area by using the semi variance analysis and variance decomposition analysis method (SOC) and total nitrogen (TN) factors were studied including the 13C content and soil spatial variability and influence; selected two kinds of different community types in plots, comparative analysis of different plant community types (parviflora and Schima in Schima parviflora Fagus lucida community Fagus lucida) on SOC and TN spatial distribution, discusses its influence mechanism possible. The main results are as follows: a moderate spatial autocorrelation of soil surface HA 25 plots of Badagong mountain and sub surface SOC and TN, but the surface soil spatial autocorrelation strength is lower than subsurface soil.SOC and TN in 2M The following is a strong scale spatial variability, presumably with the micro topography and soil microorganisms closely related to micro environmental factors on the spatial variability in the scale of SOC and TN play an important role. The soil factor is the main factor affecting the variation of SOC and TN, the space of Badagong mountain soil pH, available phosphorus and clay content and SOC the content has the remarkable correlation. Impact of vegetation on the content of SOC showed the scale effect, in the 20 m scale effect on soil carbon content more than 5 m and 10 m scale. Although the interpretation of small amount of topographic factors on SOC and TN, but Mantel's test still showed a significant terrain related to the content of SOC. The spatial structure factor as a collection of various scale space process, has an important influence on the spatial variation of SOC and TN. With complex interactions between various factors. Badagongshannational 25 ha soil 13C values change A smaller range, the value of surface soil 813C was significantly lower than that of subsurface soil, and showed moderate spatial autocorrelation. The soil 613C value in the 2 m scale still has a certain degree of variability, may be mainly caused by isotope fractionation by microorganisms resulting from SOC or other space process caused by soil, vegetation and terrain factors the soil 13C values of the total amount of explained variation in surface and subsurface between roughly, but explain the spatial structure factor on subsurface soil 13C was significantly higher than that in the surface soil. To show the effect of subsurface soil and stable carbon isotopic composition is more susceptible to a variety of spatial processes. The vegetation factors explain small vegetation attributes involved in this study at the same point difference is not enough on the composition of soil carbon stable isotope effect. The soil factor may be through the regulation of microbial isotope Fractionation effect of spatial variability of soil 13C. Topographic factors on soil 813C value explained mainly through the interaction of spatial variability and spatial structure factors. Has a significant impact on vegetation community types SOC and TN spatial distribution. For SOC and TN content, the differences between different community types mainly in the surface soil (0-10 cm), and speculated that the source of litter and the carbon intensive leaching. The soil carbon and nitrogen reserves, the difference is mainly in the deep soil (30-60 cm). The community types had no significant effect on soil C/N, C/N tends to be stable in the same depth of soil conditions, reflects the close relationship between the soil carbon and nitrogen among different communities. Soil 13C values had significant differences, may be caused by the differences between communities on Litterfall and fine root Delta 13C value.

【学位授予单位】：中国科学院研究生院(武汉植物园)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S714

【参考文献】