Soil Properties and Microbial Diversity at the Frontier of Laohugou Glacier Retreat in Qilian Mountains

Abstract

Glacier retreat may result in the decomposition of old organic carbon stored at the frontier of glacier retreat and the release of greenhouse gases such as CO₂ and methane into the atmosphere. This process may gradually transform the soil in the region from its original status as a carbon sink into a carbon source, thus producing a positive feedback effect on global warming. In this study, Laohugou Glacier No. 12, Qilian Mountains, China, was taken as the research object, and the newly melted soil (Q1) at the frontier of glacier retreat and the sandy soil (Q2) on the bank of the nearby river were collected. The content of accumulation of organic matter (AOM) in Q1 soil was 5.56 ± 0.27 g/kg, and the total nitrogen was 0.60 ± 0.03 g/kg, which was significantly higher than that in Q2. The soil microbial carbon metabolism of Q2 was significantly (P < 0.01) higher than that of Q1 and the ability of organic matter to decompose was greater. The alpha diversity index of bacteria, fungi and archaea of Q2 was significantly higher than that of Q1. It may be that there were dominant species in Q1 causing the lower species evenness. The archaea metabolic function genes in Q1 were higher than those in Q2 because archaea are better adapted to a frozen environment. Bacterial carbohydrate and amino acid metabolism was abundant in Q2 and was related to microbial transformation of the carbon source into CO₂.