黄土丘陵区铁杆蒿群落和长芒草群落地上生物量及土壤养分效应

Change of underground biomass and soil fertility with restoration stages of Artemisia gmelinii and Stipa bungeana in Loess Hilly Region

为了明确黄土丘陵区典型植被演替过程中植被与土壤的互动效应,为植被恢复提供依据,采用野外调查和室内分析的实验方法,结合逐步回归和通径分析数据处理方法,研究该区铁杆蒿群落和长芒草群落随着恢复演替的进行,地上生物量、地下生物量、土壤养分的动态变化及其地上生物量与环境因子的关系,并对2种群落进行比较分析。结果表明:随着退耕年限的增加,铁杆蒿和长芒草群落的地上生物量、地下生物量呈逐渐增加的趋势;2种群落的土壤有机质和全氮也都呈增加的趋势,且同群落生物量的变化趋势步调基本一致;全磷和硝态氮也表现了总的增加趋势,但与生物量的变化趋势不太一致。逐步回归与通径分析表明,对铁杆蒿群落地上生物量影响较大的环境因子是有机质、黏粒质量分数和水分含量,其中有机质质量分数和水分含量表现为正效应,即生物量随有机质质量分数和土壤水分含量的增加而增大,土壤黏粒质量分数表现为负效应;对长芒草群落影响较大的是海拔、坡位、年限和全氮质量分数。

This study aims to better understand the interaction between typical vegetation in different succession stages and soil of Loess Hilly Region and to supply evidences for the initiatives of vegetation restoration.Based on field investigation and laboratory experiments,statistical methods of Stepwise Regression Analysis and Path Analysis were employed in this study.We studied the change of aboveground biomass,underground biomass and soil fertility of Artemisia gmelinii and Stipa bungeana in Loess Hilly Region with restoration stages and the relationship of aboveground biomass with environment factors.The results show that the aboveground and underground biomass of the two communities both increased with restoration stages,and so did their soil organic carbon,total nitrogen,total phosphorus and NO3-N.The change trend of soil organic carbon and total nitrogen was largely agreed with community biomass,but the change trend of total phosphorus,NO3-N was not very coherent with community biomass.The results of Stepwise Regression Analysis and Path Analysis suggest that factors affecting Artemisia gmelinii greatly were contents of soil organic matter,water and clay.Among the three factors,the former two factors performed positive effect,and the later had negative effect.For Stipa bungeana,altitude,slope position,restoration stages and total nitrogen were major factors influencing its biomass.