改变碳输入对南亚热带海岸沙地典型天然次生林土壤呼吸的影响

土壤呼吸是陆地生态系统碳循环的一个重要过程,开展环境因子和改变碳输入对土壤呼吸影响的研究具有重要意义.2015年3月-2016年2月,在南亚热带海岸沙地典型天然次生林中设置去除根系、去除凋落物、加倍凋落物和对照4种处理,采用LI-8100连续观测改变碳输入对土壤呼吸的影响.结果表明:改变碳输入没有显著影响l0cm土壤温度和湿度(P＞0.05);不同处理土壤呼吸速率存在明显的季节变化,表现为夏高冬低,最大值出现在5月或者6月,最小值出现在11月或12月;土壤呼吸速率的年均值为加倍凋落物＞对照＞去除根系＞去除凋落物,不同改变碳输入方式均降低了土壤呼吸的Q10值;矿质土壤呼吸、凋落物呼吸和根系呼吸对土壤总呼吸的贡献分别为41.24％、43.29％和15.45％;不同处理土壤呼吸速率分别与土壤温度和湿度呈显著的指数和线性正相关(P＜0.05),双因子模型能解释土壤呼吸变异的45％ ～ 69％;改变碳输入影响土壤可溶性有机碳和微生物生物量碳,不同处理土壤呼吸速率与可溶性有机碳和微生物生物量碳呈正相关.因此,改变碳输入引起土壤易变碳的变化进而影响土壤呼吸.

Changes of carbon input influence soil respiration in a typical natural secondary forest on southern subtropical sandy coast

[Background] Globally,the pool of carbon in soils is greater than the pool contained in vegetation or the atmosphere,and changes in soil carbon content can therefore greatly affect the global carbon budget.Soil respiration is an essential process of carbon cycling in terrestrial ecosystems,thus the knowledge about influence of environmental factors and carbon input on soil respiration is critical for ecosystem management.[Methods] Four 20 m × 20 m permanent fixed plots were established in a natural secondary forest in December 2014 in southeastern coast of Fujian Province,China,and four carbon input manipulations of root exclusion,litter exclusion,double litter and control(normal carbon inputs) were carried out in each plot.Monthly soil respiration (Rs) under different carbon input manipulations were measured by Li-8100 from March 2015 to February 2016.In addition,the dissolved organic carbon and microbial biomass carbon were determined after Rs measurement.One-way analysis of variance (ANOVA) with Duncan's multiple comparison method was used to test the differences of Rs,soil temperature and soil moisture between different carbon input manipulations,besides the linear and nonlinear regression models were used to describe the relationship between seasonal Rs,soil temperature and soil moisture.[Results] The results showed that no significant difference was found for soil temperature and soil moisture at 10 cm depth between different treatments (P ＞ 0.05).The seasonal pattern of Rs was obviously,which was higher in summer and lower in winter during the study period,and the highest fluxes observed in May 2015 or June 2015 and the lowest fluxes occurred in November 2015 or December 2015.The range of annual mean Rs for different treatments was double litter ＞ control ＞ root exclusion ＞ litter exclusion,and all Q10 values in different carbon input manipulations were lower than that in control.The contribution of mineral soil,litter layers and roots to total soil respiration was 41.24％,43.29％ and 15.45％,respectively.Rs was significantly and exponentially correlated with soil temperature and linearly and positively correlated with soil moisture at 10 cm depth (P ＜ 0.05).The bifactor models integrated W10with T10 explained 45％ ～ 69％ of the variations for Rs.The soil dissolved organic carbon and microbial biomass carbon were also influenced by carbon input changes,and the mean Rs significantly correlated with soil dissolved organic carbon and microbial biomass carbon concentration.[Conclusions] Our findings suggested that carbon input manipulations induced changes in soil labile carbon,and subsequently caused significant effects on soil respiration.