Chamber measured soil respiration: A useful tool for estimating the carbon balance of peatland forest soils?

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• 作者：Paavo Ojanen^a ; ^{paavo.ojanen@helsinki.fi} ; Kari Minkkinen^a ; ^{kari.minkkinen@helsinki.fi} ; Annalea Lohila^b ; ^{annalea.lohila@fmi.fi} ; Tiina Badorek^a ; ^{tiina.badorek@helsinki.fi} ; Timo Penttilä ; ^c ; ^{timo.penttila@metla.fi}
• 关键词：螖Csoil ; carbon balance of soil ; 螖Cbiom ; carbon balance of biomass ; GPPeco ; ecosystem photosynthesis ; GPPfloor ; photosynthesis of forest floor vegetation ; GPPtrees ; photosynthesis of trees ; L ; litter production ; Labove ; litter production of the abovegrou
• 刊名：Forest Ecology and Management
• 出版年：2012
• 期刊代码：54_03781127
• 类别：abs
• 出版时间：1 August, 2012
• 卷：277
• 期：Complete
• 页码：132-140
• 文件大小：298 K

摘要

Peatlands drained for forestry have a high potential for CO₂ emissions due to peat decomposition. Accurate estimates of either these emissions or soil carbon balances (螖C_soil) on large areas are needed for national greenhouse gas inventories and as input for earth system models. The measurement of forest floor respiration (R_floor) or heterotrophic soil respiration (R_het) by portable chambers offers an affordable tool for extensive studies. So far, the reliability of respiration chamber based calculations of 螖C_soil has not been tested and the prerequisites for their use have not been discussed. However, the method is being used in greenhouse gas inventories.

In this study, we compared the results of two chamber based methods against a reference estimate based on eddy covariance measurements. In the first method, 螖C_soil was calculated by subtracting R_het from the litter input into the soil. In the second method, R_floor was subtracted from the entire allocation of carbon (C) into the soil. A four-year detailed dataset of C dynamics of a drained peatland forest in southern Finland served as the test material.

The R_het method produced results close to those of the reference method, but the results were sensitive to the choice of root turnover rates used in the estimation of litter input. The R_floor method resulted in a clear underestimation of soil C sink: the accurate estimation of the large photosynthesis and respiration fluxes needed for the calculation turned out to be difficult.

In our opinion, the R_het method could be used to identify hot spots of forest soil CO₂ emissions and for balance estimation for large areas. Further development of models for estimating the photosynthesis and respiration fluxes is needed for the application of the R_floor method. As the estimation of 螖C_soil by subtracting C output from C input is inherently sensitive to bias in the estimation of the input and output, the accuracy of both methods needs further testing with extensive datasets.