喀斯特森林不同地形凋落物现存量及养分特征

Characteristics of Litter Stock and Nutrients in Different Land Forms in Karst Forest

分析茂兰喀斯特森林不同地形条件下,凋落物层现存量和主要养分元素含量、储量及其释放特征,以及与土壤理化性质相关关系,为探讨茂兰喀斯特森林生态系统的养分循环机制提供理论依据。在贵州茂兰国家级喀斯特森林自然保护区内,从坡地、槽谷和漏斗3种典型地形的地表采集各分解层的凋落物和矿质土土壤样品,测定凋落物层的现存量和主要养分元素含量、储量、释放率,使用Pearson相关性分析,探究土壤理化性质与凋落物层现存量、养分元素含量之间的相关性。结果表明:1)不同地形之间以及不同分解层之间,凋落物层现存量差异较大,具体表现为坡地>槽谷>漏斗和已分解层>半分解层>未分解层。2)凋落物各分解层养分元素含量及储量均表现为C>Ca>N>Mg>K>P,不同地形之间凋落物养分总储量存在显著差异,且均以坡地最高,各养分元素因地形和分解层的差异而表现出不同的释放率。3)凋落物现存量与土壤碳、氮含量、含水量、容重、pH之间存在显著相关性。表明地形对喀斯特森林凋落物养分释放分布特征及分解速率具有显著影响,其中坡地森林地表凋落物分解较快,营养元素循环周期较短。

In order to provide a theoretical basis for the further investigation of the nutrient circulation mechanism in Maolan karst forest, the existing stock of litter layer and the contents of main nutrient elements, reserves and release characteristics of the litter layer under different terrain conditions, as well as the their relationships with soil physico-chemical properties were analyzed.The experiment was conducted in the Maolan National Karst Forest Nature Reserve in Guizhou, in which litter and soil samples were collected from different decomposed layers on the surfaces of three typical morphologies: slope, trough valley, and funnel land forms.Relative indicators were measured, such as the existing amount of litter layer, contents of the main nutrients and release rate.Pearson correlation analysis was adopted to explore the correlationships between the physical and chemical properties of the soil and the existing amount of litter layer, as well as nutrient contents.The results showed that 1) significant differences in the existing amount of litter layer forms were found between different land forms and decomposition layers, and the orders were slope>trough valley>funnel, and fully decomposed layer> fragmented litter layer> fresh litter layer.2) The contents and reserves of nutrient elements in each decomposition layer of litter were shown as C>Ca>N>Mg>K>P.There were significant differences in the total nutrient reserves of litter among different land forms, and the slope was the highest.Each nutrient element showed different release rates due to the difference in topography and decomposition layer.3) There was a significant correlation between litter existing and soil carbon, nitrogen content, water content, bulk density, and pH.It was concluded that land forms had significant impacts on the nutrient release distribution characteristics and decomposition rate of litter in Karst forests.The decomposition rate of litter on the sloping forest surface was faster, and the cycle of nutrient elements was shorter.