生物土壤结皮对土壤微生物量碳的影响

微生物量碳是土壤有机碳的重要组成部分,是判别退化系统生态修复的重要指标之一。为了探明生物土壤结皮对土壤微生物量碳的影响,以腾格里沙漠东南缘的人工固沙区不同生物土壤结皮覆盖的沙丘土壤为研究对象,根据固沙年限的不同将样地分为4个不同的区进行采样(1956、1964、1981年和1987年固沙区),并以流沙区为对照。与流沙区相比较,54龄、46龄、29龄和23龄固沙区的真藓结皮和藻结皮的存在均可显著提高其下土壤微生物量碳（P<0.05）,且固沙年限与结皮下土壤微生物量碳存在正相关关系；真藓结皮和藻结皮对其下土壤微生物量碳的影响仅限于0~20 cm的土层,随着土层的加深,其影响逐渐减弱,到20~30 cm土层与对照相比已无显著差异（P>0.05）。因此,对生物土壤结皮的干扰可能会造成土壤微生物量碳的损失。

Effect of Biological Soil Crusts on Soil Microbial Biomass Carbon Content

Microbial biomass carbon(MBC) is an important component of soil organic carbon and an important indicator of degraded ecosystem restoration assessment.To understand how biological soil crusts affect soil MBC content in the southeastern edge of the Tengger Desert,China,sandy soil under different types of biological soil crusts was sampled at artificially stabilized sand dunes,and sandy soil at mobile sand dunes was also sampled as the contrast.The sampling plots at the artificially stabilized sand dunes were distributed in four areas with different sand-fixing time(the sand dune were stabilized in 1956,1964,1981 and 1987,respectively).Compared with the contrast in the mobile sand dunes,Bryum argenteum crust and algae crust could significantly increase the content of soil MBC in the 54-year-old,46-year-old,29-year-old and 23-year-old stabilized sand dunes(P<0.05).Soil MBC content under crusts is positively correlated with the sand dune fixation time(P<0.05).Bryum argenteum and algae crusts could significantly increase the content of MBC at 0-20 cm soil layer.However,the effect decreases gradually as soil depth increases and no significant difference is showed at 20-30 cm soil layer(P>0.05).Therefore,disturbances to biological soil crusts may lead to the loss of soil MBC.