Abstract
Abstract. To better understand the effect of dissolved organic carbon (DOC) transported by hydrological processes (rainfall, throughfall, litter leachate, and surface soil water; 0–20 cm) on soil respiration in tropical rainforests, we detected the DOC flux in rainfall, throughfall, litter leachate, and surface soil water (0–20 cm), compared the seasonality of δ13CDOC in each hydrological process, and δ13C in leaves, litter, and surface soil, and analysed the throughfall, litter leachate, and surface soil water (0–20 cm) effect on soil respiration in a tropical rainforest in Xishuangbanna, south-west China. Results showed that the surface soil intercepted 94.4 ± 1.2 % of the annual litter leachate DOC flux and is a sink for DOC. The throughfall and litter leachate DOC fluxes amounted to 6.81 and 7.23 % of the net ecosystem exchange respectively, indicating that the DOC flux through hydrological processes is an important component of the carbon budget, and may be an important link between hydrological processes and soil respiration in a tropical rainforest. Even the variability in soil respiration is more dependent on the hydrologically transported water than DOC flux insignificantly, soil temperature, and soil-water content (at 0–20 cm). The difference in δ13C between the soil, soil water (at 0–20 cm), throughfall, and litter leachate indicated that DOC is transformed in the surface soil and decreased the sensitivity indices of soil respiration of DOC flux to water flux, which suggests that soil respiration is more sensitive to the DOC flux in hydrological processes, especially the soil-water DOC flux, than to soil temperature or soil moisture.
Highlights
Dissolved organic carbon (DOC), the most active form of fresh carbon, stimulates microbial activity and affects CO2 emissions from the surface soil (Bianchi, 2011; Chantigny, 2003; Cleveland et al, 2006)
Our results showed that the throughfall carried most of the dissolved organic carbon (DOC) (113.5 ± 8.5 kg C ha−1 yr−1) through the hydrological processes in the Xishuangbanna tropical rainforest, which amounted to 6.81 % of the net ecosystem exchange (NEE) (1.67 × 103 kg C ha−1 yr−1) (Tan et al, 2010) in this tropical rainforest in south-west China
The litter leachate DOC (127.7 ± 8.5 kg) accounted for 7.23 % of the NEE in this forest. This result indicates that the throughfall DOC is an important component of the tropical rainforest carbon budget
Summary
Dissolved organic carbon (DOC), the most active form of fresh carbon, stimulates microbial activity and affects CO2 emissions from the surface soil (Bianchi, 2011; Chantigny, 2003; Cleveland et al, 2006). This indicates that the proportion of DOC that leaches from the soil is a crucial component of the carbon balance (Kindler et al, 2011; Stephan et al, 2001), which is estimated as the high ratio of DOC flux to net ecosystem exchange (NEE) in forests, grasslands, and croplands (Sowerby et al, 2010). The soil retains most of the DOC that reaches the soil surface from the throughfall and litter leachate
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