Degradation dynamics and microbial processes in yak dung on the Tibetan Plateau

IF 9.8 1区 农林科学 Q1 SOIL SCIENCE
Zhiyang Zhang, Yi Jiao, Steffen Kolb
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引用次数: 0

Abstract

Yak dung is an input to the carbon (C) and nutrient cycles that maintain ecosystem functions on the Tibetan Plateau. Yak dung is C and nutrient-rich excreta that is conducive to the growth and metabolic activities of bacterial communities, thus predicting that more bacterial than fungal processes are responsible for the degradation of yak dung. A three-year yak dung degradation experiment in a yak-grazing alpine rangeland was designed to investigate the changes in dung moisture content, chemical and enzymatic properties, and bacterial and fungal communities during degradation, as well as to explore how these parameters may regulate the degradation of yak dung. After three years of decomposition, yak dung had a 79 % reduction in mass, and most of the mass loss occurred within the first 2 years. Cellulosic polymers, especially cellulose and hemicellulose, determined the rate of yak dung degradation. The main changes in dung bacterial communities occurred during the first 2 years of degradation, largely related to changes in moisture and available substrates (e.g., dissolved organic C, dissolved organic nitrogen (N), ammonium, nitrate, and available phosphorus). In contrast, dung fungal communities did not change until 1.5–3 years of degradation, in response to the total substrates (e.g., total C and N). The relative abundances of Proteobacteria, Bacteroidota, Firmicutes, Basidiomycota, and Ascomycota, and the activities of endo-cellulases, exo-cellulases, β-1,4-glucosidase, and β-1,4-xylosidase, which were associated with cellulose and hemicellulose degradation, decreased during decomposition. The relative abundances of Actinobacteria, and activities of peroxidases and polyphenol oxidase were positively correlated with dung lignin content. Structural equation modeling suggested that degradation of lignocellulose in dung was mainly the consequence of bacterial community activities. Additionally, moisture was the most important abiotic factor influencing lignocellulose degradation, as it can directly affect dung substrate availability, and ultimately bacterial communities and associated enzyme activities. As the microbial degradation of lignocellulose in yak dung is strongly related to moisture, any change to the rainfall pattern in the future is expected to influence yak dung degradation in this alpine region.

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来源期刊
Soil Biology & Biochemistry
Soil Biology & Biochemistry 农林科学-土壤科学
CiteScore
16.90
自引率
9.30%
发文量
312
审稿时长
49 days
期刊介绍: Soil Biology & Biochemistry publishes original research articles of international significance focusing on biological processes in soil and their applications to soil and environmental quality. Major topics include the ecology and biochemical processes of soil organisms, their effects on the environment, and interactions with plants. The journal also welcomes state-of-the-art reviews and discussions on contemporary research in soil biology and biochemistry.
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