[Effects of addition of organic carbon with different chemical structure on the fate and accumulation of exogenous carbon in red and sandy soils]. / çº¢å£¤å’Œé£Žæ²™åœŸæ·»åŠ ä¸åŒåŒ–å­¦ç»“æž„æœ‰æœºç¢³å¯¹å¤–æºç¢³åŽ»å‘åŠç´¯ç§¯è´¡çŒ®çš„å½±å“.

Plant litter input has important influences on soil CO2 emission and soil organic carbon (SOC) formation in terrestrial ecosystem. However, it is not well known for the fate of carbon when exogenous organic matters with different chemical structures are added to soil with different textures. In this study, we added the uniformly 13C-labelled substrates of glucose, starch, and cellulose to red soil and sandy soil, and compared the net 13C accumulation and recovery and its proportions in soil releasing CO2, SOC, dissolved organic carbon (DOC) and microbial biomass carbon (MBC) pools. The results showed that δ13C values increased after exogenous substrate additions in CO2, SOC, DOC, and MBC, and that the peaks of δ13C in CO2 pool appeared delay with increasing chemical structure complexity. The fate of exogenous C and its contributions of different C pools were significantly influenced by exogenous C types, soil types, and incubation times. In sandy soil, the added exogenous C was more mineralized as CO2, with the net accumulation and recovery of 13C in CO2 pool decreasing in the order of glucose>starch>cellulose. In red soil, more exogenous C was transferred to SOC pool, with the net accumulation and recovery of 13C in SOC pool decreasing in the order of glucose>starch>cellulose. Our results implied that the chemical structure of exogenous substrates and soil texture together controlled the fate and accumulation of exogenous organic carbon.

[Effects of addition of leaf litter with different chemical properties on soil organic carbon mineralization and priming effect]. / ä¸åŒåŒ–å­¦æ€§è´¨å¶å‡‹è½ç‰©æ·»åŠ å¯¹åœŸå£¤æœ‰æœºç¢³çŸ¿åŒ–åŠæ¿€å‘æ•ˆåº”çš„å½±å“.

Litter inputs can affect the mineralization of soil organic carbon (SOC). However, it is yet unknown how the input of leaf litter with different chemical properties drives SOC mineralization and priming effect. In this study, 13C-labeled leaf litter of six tree species were added to soil cores (10 cm depth) collected from a natural secondary forest in subtropical region. We examined the effects of different leaf litters on total soil CO2, litter-derived and soil-derived CO2 emission rates and accumulation and priming effect. We further examined the relationships between litter chemical properties and CO2 accumulation and priming effect. Our results showed that leaf litter addition increased total soil CO2 and soil-derived CO2 emission rates and accumulations, and that there were positive priming effects ranging from 68% to 128%. Soil organic carbon mineralization and priming effects varied among tree species. The Pearson correlation and stepwise multiple linear regression analysis showed that the litter-derived CO2 accumulation had negative correlation with leaf litter C, P and cellulose concentrations, whereas the soil-derived CO2 accumulation were positively correlated to litter C:N and lignin:N. The results implied that tree species could influence SOC mineralization and litter-induced priming effect. Thus it could mitigate soil C loss when we afforested plantation with high quality leaf litter in subtropical region.