Ecosystem Carbon Pool And Soil Labile Carbon In The Restoration Of Eroded Degraded Ecosystem

Ecosystem degradation in soil and water losses region of South China is serious, where soils are often derived from granite. Restoration of eroded degraded ecosystems is important for the improvement of ecosystem and development of sustainable economy. Some controlled management have been done for several years, and restoration of plant diversity, benefit of soil and water conservation, productivity, soil fertility and climatic conditions have been studied while a relatively few research were carried out on ecosystem carbon pool and soil labile carbon in restored ecosystems. Therefore, ecosystem C storage and soil labile C, were studied in regeneration forest through planting shrub (treatment I), orchard (treatment II), grassland (treatment III), and two control ecosystems (viz. seriously degraded ecosystem I and native forest II) in Hetian town, Changting county, Fujian.The results showed that:1. Total carbon storage in three ecosystems of regeneration forest through planting shrub (treatment I), orchard (treatment II), grassland (treatment III) was 135.6, 28.2and 37.3t.hm^-2 respectively. The corresponding C stocks of biomass and soil for three treatments were 91.9, 2.5 and 5.5 t.hm^-2 for biomass C, and 43.7, 25.7 and 31.8 t.hm^-2 for soil C respectively.2. Soil organic C storage in 0-60 cm soils in regeneration forest through planting shrub, orchard, grassland were 3.67, 2.15 and 2.67 times higher than that in control I (bare land) respectively, while being 55.17%, 32.37% and 41.12% of that in control II (native forest) respectively. There was significant difference in organic C storage in different soil layers between three restoration ecosystems and control II. Similarly, difference in organic C storage in topsoils between three restoration ecosystems and control I was significant. Further, significant difference in soil organic C storage was found between treatment I and control I for 10-20cm soil layer. While difference in soil organic C storage betweentreatment II and treatment III at 10-20cm depth, and between three treatments and control I at 20-60cm depth were not significant.3. Content and storage of light fraction soil organic C (LFOC) at topsoils among three treatment ecosystems and control II differed significantly. At surface 10cm soil, light fraction soil organic C storage in the control II was 1.65 and 4.88 times higher than those in treatment I and treatment II respectively, while being 63.17% of that in treatment III. The proportion of soil organic C as LFOC in three treatments was the highest in treatment III, followed by treatment I and treatment II. Also, there was significant difference between three treatments.4. Dissolved organic C contents at 0-5cm depth in different treatments were all greater than those at 5-10 cm depth. DOC content at top 5cm soils in three treatments were as much 8.63, 6.32 and 3.97 times as that in control I respectively. The corresponding value in control II was 12.03 times higher than that in control I. Further, significant differences in DOC content at surface 5 cm soils among three treatments and controls were found. At 5-10cm soil layer, DOC content in control II was as much 1.34, 4.63 and 4.26 times as those in treatment I, II and III respectively, while the value in control was 8.86% of that in control II.5. Microbial biomass C (MBC) content at 0-5cm depth in different ecosystems was higher than that at 5-10cm depth except for control I. There were significant difference in microbial biomass C content at top 5cm soils among three treatments and two controls (P<0.05). Contents of microbial biomass C in treatment I, II and III were 10.75, 8.38 and 3.56 times higher than that in control I respectively, while being 74.70%, 58.27% and 24.75% of control II respectively. For 5-10cm layer, microbial biomass C content in control II was 1.46, 3.72 and 4.01 times higher than those in three treatments respectively, while the latter was 5.46, 2.15 and 1.99 times higher than that in control I respectively.6. There are positive relationships between SOCT and microbial, light fraction carbon, and dissolved carbon. SOCt was positively correlated with microbial 0(1^=0.94), SOCt was positively correlated with LFC(r2=0.75), SOCt was positively correlated with DOC(r2=0.88), These positive relationships indicate that labile C increased with SOCT. Three SOCL were positively correlated: microbial carbon, light fraction carbon, and dissolved carbon. DOC was positively correlated with MBC(r2=0.89), LFC was positively correlated with MBC(r2=0.84), MBC was positively correlated with DOC(r2=0.70).