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邓 翠, 吕茂奎, 曾 敏, 张康靖, 张 浩, 谢锦升
土壤呼吸作为土壤与大气CO2交换的重要环节,其排放量的大小在一定程度决定了土壤碳库的源与汇。研究红壤侵蚀区植被恢复对土壤呼吸及其温度敏感性(Q10)值的影响,对于理解土壤有机碳积累机制具有重要意义。本研究选取了福建省河田镇未治理地及邻近恢复13 a和31 a的马尾松人工林,对土壤呼吸进行监测。结果表明:未治理地土壤呼吸并无显著季节差异,恢复13 a和恢复31 a后土壤呼吸季节差异显著;恢复13 a和31 a土壤呼吸与Q10显著高于未治理地,恢复13 a和31 a土壤呼吸与Q10未见显著差异。季节尺度上,土壤呼吸速率与土壤水分相关性弱,而与土壤温显著相关,未治理地土壤温度仅能解释土壤呼吸速率的25.3%,而恢复后土壤温度则解释了土壤呼吸速率的48.8%~66.5%;结构方程模型表明,对土壤呼吸和温度敏感性影响最大的分别是凋落量和土壤微生物。研究为进一步认识退化生态系统土壤碳动态机制提供依据。
关键词:  植被恢复  土壤呼吸  土壤呼吸温度敏感性Q10  凋落物量
Impacts of Vegetation Restoration on Soil Respiration and its Sensitivity to Temperature in Eroded Red Soil Area
DENG Cui, LÜ Maokui, ZENG Min, ZHANG Kangjing, ZHANG Hao, XIE Jinsheng
School of Geographical Sciences,Fujian Normal University
【Objective】 Soil carbon pool plays an important role in the process of global change. In eroded red soil, restoration of vegetation may enhance soil carbon sequestration, which is of great significance to retardation of global change. But how it does still remains unclear. Soil respiration is an important link between the soil and the atmosphere in CO2 exchange. To a certain extent, the flux of soil carbon emission determines whether the soil is a sink or a source of carbon in the ecosystem. It is, therefore, essential to study impacts of vegetation restoration on soil respiration and its temperature sensitivity (Q10) for better understanding of the mechanism of soil carbon sequestration in severely eroded red soil. 【Method】In this study, two Pinus massoniana plantations, 13 years old (Y13) and 31 years old (Y31), in Hetian Town, Fujian Province, were selected for comparison with a tract of virgin land (Y0) nearby. Soil respiration in the three tracts of land were monitored monthly with a LI–8100 (Nebraska, USA) from April 2015 to March 2016, and soil temperature (in the 0~5 cm soil layer), soil water content (in the 0~12 cm soil layer), litter biomass, soil organic carbon, total nitrogen, C/N and soil microbial biomass carbon were also determined simultaneously. Besides, a structural equation model was developed to analyze relationships of soil respiration and its temperature sensitivity with soil and its environment factors so as to identify potential driving factors affecting soil respiration and its temperature sensitivity.【Result】 The highest peaks of soil respiration rate appeared during the period from June to August, while the valleys did from December to February, Soil respiration varied in the range of 0.89~1.44 μmol•m-2•s-1 in Y0, 2.00~3.85 μmol•m-2•s-1 in Y13 and 1.78~4.16 μmol•m-2•s-1 in Y31. Obviously it did not vary much seasonally in Y0 (P>0.05), but did in Y13 and Y31 (P<0.05). Soil respiration was significantly higher in Y13 and Y31 than in Y0 (P<0.05), but did not differ much between Y13 and Y31, and was much more sensitive to temperature in Y13 and Y31 than in Y0 (P<0.05), with Q10 being 1.66, 1.58 and 1.27 respectively. On a seasonal scale, no apparent relationship was observed between soil respiration rate and soil water content, but a positive one was between soil respiration and soil temperature in the surface layer (5 cm), with soil temperature explaining 25.3% of the variation of soil respiration rate in Y0, 66.5% in Y13 and 48.8% in Y31; Analysis of the affecting factors with the structure equation model demonstrate that soil respiration and its temperature sensitivity are dominantly affected by litter biomass and soil microbes.【Conclusion】All the findings in this study demostrate that ecological restoration significantly increases soil respiration, with increased litter input and henced enhanced soil biochemical processes being the dominant factors. It is, therefore, expected that they may serve as reference for the further study on rules of the variation of soil respiration and machanisms of the factors affecting ecological restoration in degraded ecosystems.
Key words:  Vegetation restoration  Soil respiration  Q10  Litter biomass