滇西北纳帕海高原湿地区域退化草甸土壤有机碳含量特征

摘要

为了解气候变化和人类活动双重影响下纳帕海高原湿地区域有机碳含量特征,采用空间格网状抽样调查方法,对区域内退化系列下湿地草甸w(SOC)(SOC为土壤有机碳)特征进行研究.结果表明:①随着草甸的退化及土壤深度的增加,土壤含水量呈下降趋势,土壤容重呈增加趋势;②从无退化草甸到重度退化草甸,植被地上生物量从321.4 g/m2降至142.1 g/m2;③在地表至地下50 cm深度范围内,从无退化到重度退化草甸,w(SOC)分别为28.21、20.59、18.01、14.81 g/kg,湿地草甸退化导致w(SOC)下降了近50％,ρ(SOC)从40.92 kg/m3降至25.23 kg/m3;④狼毒草甸的w(SOC)、ρ(SOC)等均表现出相对较高的水平,仅次于无退化样地;⑤w(SOC)与土壤含水量呈显著正相关(P＜0.05)、与土壤容重呈显著负相关(P＜0.01).湿地草甸植被退化所形成的地上植被盖度及生物量的下降,以及土壤含水量的下降和土壤容重的增加,最终导致近50％左右的w(SOC)发生流失;此外,若从同类研究中季节性淹水的沼泽或沼泽化草甸转变为该研究中常年出露于水面的草甸景观后,在20 cm土壤深度内将导致45％以上的w(SOC)损失.%The Napahai plateau wetland,located in the low latitude and high altitude areas of China where the economic development is relatively backward,is sensitive to climate change.Small changes of natural environment have a profound impact on the region.In order to understand the characteristics of soil organic carbon content under the dual influence of climate change and human activities in the Napahai plateau wetland,the characteristics of soil organic carbon (SOC) in meadows with different degradation in the area were studied by spatial grid sampling survey.The results indicated that:(1) With the meadow vegetation degradation and soil depth increasing,the soil water content decreased and bulk density increased significantly.(2) From non-degraded meadow to severely degraded meadow,the aboveground biomass of vegetation declined from 321.4 g/m2 to 142.1 g/m2 continuously.(3) At 50 cm soil depth,w (SOC) of non-degraded meadow,lightly degraded meadow,moderately degraded meadow and severely degraded meadow were 28.21,20.59,18.01,and 14.81 g/kg respectively.With the degradation degree increasing,the loss w(SOC) was about 50％,and the SOC density decreased from 40.92 kg/m3 to 25.23 kg/m3.(4) SOC density of Stellerachamae jasme meadow showed a relative higher level,lower only than the non-degraded meadow.(5) There was significant positive correlation between w (SOC) and soil water content (P ＜ 0.05),and significant negative correlation between w(SOC) and soil bulk density (P ＜ 0.01).The research shows that the decrease of vegetation cover and biomass,the decrease of soil water content and the increase of soil bulk density resulted from the degradation of wetland vegetation,which eventually led to the loss of about 50％ ofw(SOC).In addition,it may cause more than 45％ of the w (SOC) loss at 0-20 cm soil depth from a seasonally flooded marsh or swamp meadow to this study's meadow landscape,which is perennial exposed above the surface of water compared to similar studies.