Soil respiration in a subtropical montane cloud forest in Taiwan

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• 作者：Shih-Chieh Chang ; Kuei-Hsiang Tseng ; Yue-Joe Hsia ; Chiao-Ping Wang ; Jiunn-Tzong Wu
• 关键词：Soil respiration ; Tropical montane cloud forest ; Chamaecyparis ; Litter decomposition
• 刊名：Agricultural and Forest Meteorology
• 出版年：2008
• 期刊代码：2_01681923
• 类别：abs
• 出版时间：15 May 2008
• 卷：148
• 期：5
• 页码：788-798
• 文件大小：1202 K

摘要

Little is known about carbon budgets for tropical and subtropical montane cloud forest (TMCF) ecosystems. Information about the soil CO₂ efflux from these ecosystems is particularly scarce, although they have been shown to have special hydrological regimes which might be important in controlling soil respiration. In this study, we used an automatic chamber system to measure soil respiration rates at the Chi-Lan Mountain forest site. The half-hourly dataset was used for analyzing the controlling factors and mechanisms of soil respiration. A manipulation experiment was conducted in the field by applying 3-fold and 1-fold aboveground litter to the soil surface and measuring the respective soil respiration rates using the static alkali chamber method. The results showed that soil respiration rates have a positive exponential correlation with soil temperature and a negative exponential correlation with soil water content. An empirical model relating soil respiration (R_s) to soil temperature (T) and soil water content (θ) is R_s = −0.095 + e^{0.88+0.10T−6.99θ} with R² = 0.83. The annual soil respiration rate calculated using this model was 176 g C m⁻² y⁻¹. This extremely low value might be caused by the permanently high soil moisture and the relative lower mean annual temperature compared to other sites that receive similar amounts of precipitation. The 3-fold and 1-fold litter treatments resulted in significantly higher soil CO₂ efflux compared to the chambers with no litter. The magnitude of difference diminished to negligible levels 6 months after treatment. About 10%of the annual soil respiration was contributed by the mineralization of fresh aboveground litter. The carbon mass loss of the decomposing litter during the first 6 months was mainly due to leaching of dissolved organic carbon (75%) and secondarily due to mineralization of CO₂. From the results of this study, we hypothesized that the TMCFs may be vulnerable to global warming since the drying of the soil may change the soil from being a carbon sink to being a carbon source, thereby releasing soil organic carbon that had been stored for a long period of time.