Changes of Soil Organic Carbon Content and Its Influencing Factors in Rubber Plantations of Different Forest Ages in Yunnan

PurposeThe change characteristics of soil organic carbon content and its influencing factors in rubber plantations of different ages in Yunnan were discussed, which could provide theoretical basis for sustainable development of rubber industry.

Method The soil samples of rubber forest with 5 ages (0-5 a, 10-15 a, 16-20 a, 26-30 a, 31-35 a) in three rubber planting areas of Jinghong City, Ruili City and Hekou County, Yunnan Province were taken as objects. Soil pH was determined by pH meter; soil water content was determined by drying method; soil organic carbon content was determined by potassium dichromate capacity-applied thermal method, and the influencing factors of soil organic carbon content were studied by redundancy analysis.

Results1) The soil organic carbon content of rubber forest in Yunnan was 7.22-22.82 g/kg, Jinghong planting area had the highest soil organic carbon content with the average value of 17.90 g/kg; the content of organic carbon was lowest in the rubber planting area of the Hekou with the average value of 10.62 g/kg. 2) The difference of soil organic carbon content among different forest ages in Yunnan was compared: the soil organic carbon content in Jinghong 0-5 a, 10-15 a and 16-20 a was significantly higher than that in 26-30 a and 31-35 a (P<0.05), the soil organic carbon content of 0-5 a in Ruili was significantly higher than that of 26-30 a and 31-35 a (P<0.05), but there was no significant difference in soil organic carbon content in Hekou, and the soil organic carbon content in surface layer (0-20 cm) was higher than that in deep layer (>20-40 cm) (P>0.05) overall. 3) Geographic position (latitude, slope, altitude), air temperature and precipitation had great influence on the spatial difference of soil organic carbon content in rubber planting area, followed by soil water content, soil pH, canopy density, height of rubber tree and so on. There was no significant difference in soil organic carbon content among different land use types (P>0.05).

ConclusionThere are spatial, age and soil changes in soil organic carbon content of rubber forest in Yunnan Province.