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外源输入碳在生物结皮土壤各碳组分中的分配特征
引用本文:姚小萌,肖波,王国鹏,张鑫鑫,李胜龙. 外源输入碳在生物结皮土壤各碳组分中的分配特征[J]. 应用生态学报, 2020, 31(11): 3737-3748. DOI: 10.13287/j.1001-9332.202011.039
作者姓名:姚小萌  肖波  王国鹏  张鑫鑫  李胜龙
作者单位:1.中国农业大学土地科学与技术学院, 北京 100193;2.农业农村部华北耕地保育重点实验室, 北京 100193;3.中国科学院水利部水土保持研究所黄土高原土壤侵蚀与旱地农业国家重点实验室, 陕西杨凌 712100
基金项目:国家自然科学基金项目(41671221)和中国科学院“西部之光”人才培养引进计划项目(2019)资助
摘    要:研究外源新输入碳进入生物结皮后在各碳组分间的分配特征,可以为理解生物结皮参与碳地球化学循环过程提供数据支持和理论依据。本研究针对黄土高原典型苔藓生物结皮,借助13C脉冲标记技术,精确示踪外源新输入碳在生物结皮碳组分中的分配特征及其与无结皮裸地的差异,揭示生物结皮对碳循环的影响。结果表明: 1)由于生物结皮养分循环速率较慢,且与维管束植物相比,其主要生物成分苔藓的生物量有限,导致生物结皮各碳组分的13C丰度值均随时间变化表现相对平稳。2)生物结皮的各碳组分13C含量均明显高于无结皮裸地,其有机碳、微生物生物量碳、可溶性有机碳中13C含量平均分别为0.258、0.078、0.004 mg·kg-1,分别比裸地高3.1、18.5、2.6倍,且苔藓植株13C含量高达1.45 mg·kg-1。3)生物结皮改变了有机碳各组分的分配特征,其新同化的碳主要分配于活性有机碳库和结皮生物中,表现为13C在微生物生物量碳中的分配率(30.6%)高于可溶性有机碳(1.7%),而苔藓植株的13C分配率为20.3%。4)生物结皮中微生物生物量13C的转移量和库容量分别是裸地的15.7和19.5倍,但其周转率(每月2.94次)略低于裸地(每月3.30次),相应周转期是裸地的1.1倍。综上,生物结皮改变了土壤有机碳组分的分配特征,提升了碳周转速率,在干旱荒漠生态系统碳循环中的作用不容忽视。

关 键 词:生物土壤结皮  稳定同位素示踪  有机碳  微生物生物量碳  可溶性有机碳  碳周转率  
收稿时间:2020-06-23

Distribution characteristics of exogenous carbon in different carbon fractions in biocrusts-covered soil
YAO Xiao-meng,XIAO Bo,WANG Guo-peng,ZHANG Xin-xin,LI Sheng-long. Distribution characteristics of exogenous carbon in different carbon fractions in biocrusts-covered soil[J]. The journal of applied ecology, 2020, 31(11): 3737-3748. DOI: 10.13287/j.1001-9332.202011.039
Authors:YAO Xiao-meng  XIAO Bo  WANG Guo-peng  ZHANG Xin-xin  LI Sheng-long
Affiliation:1.College of Land Science and Technology, China Agricultural University, Beijing 100193, China;2.Key Laboratory of Arable Land Conservation in North China, Ministry of Agriculture and Rural Affairs, Beijing 100193, China;3.State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, Shaanxi, China
Abstract:The distribution characteristics of exogenous carbon (C) in the C fractions of biocrusts-covered soil are critical for understanding the geochemical cycling of C with biocrusts in drylands. A 13C pulse labeling experiment was conducted for moss-dominated biocrusts-covered soil and bare soil on the Loess Plateau of China with semiarid climate, with the content of 13C in different C fractions being continuously measured to determine the biocrust effects on the distribution of exogenous C in each C fraction. Our results showed that, 1) the 13C abundance of each C fraction in the biocrusts-covered soil was steadily changed with time, due to the relatively low rate of nutrient cycling in the biocrusts-covered soil and also to the relatively low biomass of moss in the biocrusts-covered soil as compared with vascular plants. 2) The 13C content of each C fraction in the biocrusts-covered soil was significantly higher than that in the bare soil. Specifically, the 13C content of total organic C (TOC), microbial biomass C (MBC), and dissolved organic C (DOC) in the biocrusts-covered soil was 0.258, 0.078, and 0.004 mg·kg-1, respectively, which was 3.1, 18.5, and 2.6 times higher than that in the bare soil. Moreover, the 13C content in the moss of the biocrusts-covered soil was 1.45 mg·kg-1. 3) The presence of biocrusts changed the distribution characteristics of each C fraction, with the newly assimilated C being mainly distributed in active organic C and biological components of the biocrusts-covered soil. In the biocrusts-covered soil, the 13C distribution in MBC (30.6%) was higher than that in DOC (1.7%), and the 13C distribution in the C of moss was 20.3%. 4) The transferred amount and storage capacity of MB13C in the biocrusts-covered soil were 15.7 and 19.5 times of that in the bare soil, respectively. The turnover rate of MB13C in the biocrusts-covered soil and bare soil was 2.94 and 3.30 times per month, respectively, implying that the turnover time of MB13C in the biocrusts-covered soil was 1.1 times longer than that in the bare soil. In conclusion, biocrusts could greatly change the distribution characteristics of each C fraction and increase C turnover rate, highlighting its important roles in C cycling in dryland ecosystems.
Keywords:biological soil crusts  stable isotope tracing  organic carbon  microbial biomass carbon  dissolved organic carbon  carbon turnover rate  
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