Soil Organic Carbon And Its Fractions Under Quercus Variabilis & Pinus Tabulaeformis Plantations In Lower Mountain Area, Beijing

Soil organic carbon plays a vital role in soil fertility maintenance of sustaining forest productivity. This paper probes into the effect mechanism of vegetation on soil organic carbon, the quality characteristic of litter in Quercus variabilis & Pinus tabulaeformis plantations, the concentration and density of the soil total organic carbon (STOC) and soil labile organic carbon (SLOC) fraction and soil enzyme activities were studied under Quercus variabilis & Pinus tabulaeformis forest in lower mountain, Beijing.The main results conclusions (1) Concentration of litter organic carbon is 370.99g-kg-1inr Quercus variabilis forest.This was significantly lower 19.35% than Pinus tabulaeformis forest.The ratios of C/N and C/P under Pinus tabulaeformis plantation were 1.58 times and 1.52 times of Quercus variabilis plantation. But there are no differences among the soil organic carbon storage, total nitrogen storage and total phosphorus storage. (2)The difference of soil concentration of readily oxidizable carbon in no litter, litter of Quercus variabilis, litter of Pinus tabulaeformis, and admixture litter.In the 0-10cm and 10-20cm soil layer, concentration of readily oxidizable carbon under litter more higher than the concentration without litter. There are no different among three treatments under litter. (3)The results showed that the concentration of the SOC, light fraction organic carbon (LFOC)and readily oxidizable carbon(ROC) in 0-20cm soil depth under Quercus variabilis forest were 14.05g-kg-1,2.97g-kg-1 and 0.38g·kg-1, respectively. These were obviously higher than those under Pinus tabulaeformis forest. The density of STOC, particulate organic carbon(POC), LFOC and ROC in 0-20cm soil depth under Quercus variabilis forest,were 39.68%,77.77% and 145.45%, respectively. These data were higher than those under Pinus tabulaeformis forest. The ratios of POC to STOC, LFOC to STOC and ROC to STOC ranged from 23.60% to 41.40%, from 9.10% to 33.33% and from 1.39% to 2.80%, respectively. So we suggested that Quercus variabilis forest was advantage of the accumulation of STOC and SLOC. (4)The soil organic carbon is present positive correlation.to POC, FLOC, ROC. (5)Peroxides enzyme activity, beta-glycosidase enzyme activity and phosphomonoesterase activity didn't show significant difference. Polyphenoloxidase activity in 0-20cm soil depth under Quercus variabilis forest is 0.2445 mmol DOPA·g-1·h-1.It is 1.83 times higher than Pinus tabulaeformis forest. There were no significant different in 5-10cm,10-20cm soil layer. (6) Beta-glycosidase enzyme activity is presnt positive correlation to SOC, SLOC.But peroxides enzyme activity and polyphenoloxidase activity are not present correlation to SOC and SLOC. The following contents belongfed to new ideas in this paper:This study for the first time with soil polyphenol oxidase, peroxidase,βglucosidase and phosphomonoesterase activity of mountain forest soils in Beijing, to research concentration and densityreadily ROC, POC and LFOC There be achived the result thatβ-Glycosidase enmzye activity, ROC, POC and LFOC present extremely significant or significant positive correlation to total organic carbon. However, due to the complexity of soil organic carbon and soil enmzye, dissolved organic carbon is suggested that to enhance the reseach of water soluble organic carbon and microbial activity of organic carbon in such soil labile organic carbon fraction, and pay attention to research method of soil enmzye.