青藏高原不同退化梯度高寒草地植被与土壤属性分异特征

Different characteristics of vegetation and soil properties along degraded gradients of alpine grasslands in the Qinghai-Tibet Plateau

高寒草地是青藏高原生态系统的重要组成部分,草地退化严重影响区域可持续发展。目前,不同草地退化的演替过程中,土壤属性与植被特征的变化机理尚未理清。本研究以青藏高原为研究对象,整合分析(meta-analysis)不同退化梯度草地的植被群落、生产力及土壤属性特征。结果表明:不同退化梯度下,植被地上和地下生物量均降低,土壤特征均呈恶化趋势。尤其是在重度退化草地中,地上生物量、地下生物量、物种丰富度和物种均匀度较未退化草地分别显著降低了42.44%、60.64%、21.08%和8.36%,土壤含水量、有机碳、全氮和全磷同样较未退化草地分别显著下降了33.57%、45.75%、22.70%和11.23%,而土壤容重显著上升了12.12%(P<0.05)。就效应比而言,植被生物量与土壤主要性质(有机碳、全氮和全磷)均呈显著正相关关系,表明草地退化过程中植被生产力与土壤性质互相影响,相较氮和磷含量,碳含量的流失非常严重。研究结果可为青藏高原地区受损草地的修复提供科学依据。

Alpine grassland is an important component of the Tibetan Plateau.The degradation of these grasslands affects regional sustainable development.The mechanisms of linkage between soil properties and vegetation traits to the succession process of grassland degradation are still unclear.In the present study,we investigated the correlation of different vegetation characteristics and soil properties with degree of degradation(non-degraded to heavily degraded)of grasslands from across the Tibetan Plateau.The results showed that the aboveground and belowground biomass and the soil properties declined along the degradation gradient.For instance,in heavily degraded grassland,aboveground biomass,below-ground biomass,species richness and species evenness were lower by 42.44%,60.64%,21.08%and 8.36%,respectively,compared to nondegraded grasslands.Soil moisture content,organic carbon,total nitrogen and total phosphorus in heavily degraded grasslands were also lower by 33.57%,45.75%,22.70%and 11.23%,respectively,compared to non-degraded grasslands.The soil bulk density was 12.12%greater in heavily degraded grasslands than in non-degraded grasslands.In terms of response ratio,we found that vegetation biomass(aboveground biomass and belowground biomass)was positively related with soil properties(organic carbon,total nitrogen and total phosphorus)(P<0.05).The findings indicated that vegetation productivity and soil properties interacted with each other in the process of grassland degradation.In addition,the carbon content loss was more serious than nitrogen and phosphorus content loss.