宁南山区典型植物根系分解特征及其对土壤养分的影响

根系分解是陆地生态系统碳和养分循环的重要地下生态过程,研究宁南山区典型植物根系分解特征及其对土壤养分的影响,能够丰富和完善陆地生态系统的物质和能量循环机制,为我国黄土高原植被恢复过程中植物与土壤之间的养分循环提供依据。连续2年研究了宁南山区3种典型植物(长芒草、铁杆蒿和百里香)根系的分解特征及其对土壤养分的影响。结果表明,长芒草、铁杆蒿和百里香根系年分解指数(K)分别0.00891、0.01128、0.01408,分解速率依次表现为百里香铁杆蒿长芒草。分解16个月后3种典型植物根系释放大量养分,其中碳的释放量在57.05—124.39 g/kg;氮的释放量在0.12—0.47 g/kg。3种典型植物根系对土壤养分的影响主要表现为:试验结束时,0—5 cm表层土壤有机碳含量提高了0.17—0.35 g/kg,5—20 cm土层土壤有机碳含量提高了0.26—0.35 g/kg。相关性分析可知,植物根系养分释放量与土壤养分含量之间存在一定的负相关关系,当土壤养分含量较低时,根系会增加养分释放量进行补充。由此可知,根系分解提高了土壤养分含量,有效的促进了养分在根系-土壤中的循环。

Effects of typical plant root decomposition on soil nutrients in southern Ningxia

Root decomposition is an important underground ecological process of carbon and nutrient cycling in terrestrial ecosystems. Studying the root decomposition characteristics of typical plants and their effects on soil nutrients in the mountainous area of southern Ningxia can provide a basis for nutrient cycling between plants and soil in vegetation restoration in Loess Plateau of China. The decomposition characteristics of three typical plant roots and the trend for soil nutrient change in the South Ningxia Loess Hilly Region of Northwest China, were studied for 2 years using the buried bag method. The results showed that the annual decomposition indices (K) of Stipa bungeana, Artemisia sacrorum, and Thymus mongolicus roots were 0.00891, 0.01128, and 0.01408, respectively, and the decomposition rate in turn showed as Thymus mongolicus > Artemisia sacrorum > Stipa bungeana. After 16 months, a substantial amount of root nutrients had been released. The release amount of carbon was 57.05-124.39 g/kg while for nitrogen it was 0.12-0.47 g/kg. The effects of three typical plant roots on soil nutrients were as follows: the contents of soil organic carbon increased by 0.17-0.35 g/kg in a 0-5 cm soil layer, and by 0.26-0.35 g/kg in a 5-20 cm soil layer. Correlation analysis showed that some negative correlation exists between the release amount of root nutrients and soil nutrient content. When the soil nutrient content is low, roots will increase nutrient release to supplement soil nutrients. This indicates that root decomposition increases soil nutrient content and effectively promotes nutrient cycling in the root-soil system.