Study On Variation And Driving Factors Of Soil Organic Carbon In Rubber Planting Areas Of China

Natural rubber is an important industrial raw material and strategic material in China.Yunnan,Hainan and Guangdong are the main natural rubber producing areas in China.However,large-scale planting of natural rubber is accompanied by many ecological and environmental problems.In recent years,unreasonable land use and fertilization methods have led to the decline of soil quality.The effect of rubber plantation on soil nutrients has become the focus of attention of all walks of life.The soil fertility of rubber plantation changes significantly with the region,forest age and soil layer,It can provide theoretical basis for soil quality and efficient development of natural rubber industry in China rubber planting areas.In this paper,the soil samples from different soil layers(0-10 cm,10-20 cm and 20-40 cm)of rubber plantations with five forest ages(0-5 a,10-15 a,16-20 a,26-30 a and 31-35 a)were collected from 8counties of Yunnan,Hainan and Guangdong provinces Single factor analysis of variance and correlation analysis were used to analyze the differences and influencing factors of soil organic carbon components in different regions,forest ages and soil layers.The results show that:(1)Characteristics of soil physical and chemical properties in rubber planting areas of ChinaThe soil nutrient status in Yunnan is higher than that in Guangdong and Hainan;The soil bulk density of rubber plantations in 10-15 a,26-30 a and 31-35 a was significantly higher than that of rubber plantations in 0-5 a(P<0.05);The content of soil nitrate nitrogen in 0-5 years old rubber plantation was significantly higher than that in other forest ages(P<0.05).In addition,there were no significant differences in soil indexes among the five rubber plantations in Yunnan and Hainan(P>0.05);Except for soil bulk density,soil nutrient index content of rubber tree decreased with the increase of soil depth,that is: 0-10 cm > 10-20 cm > 20-40 cm.(2)Soil organic carbon and its components difference in China rubber planting areaThere was no significant difference in soil organic carbon content(P>0.05)in China’s rubber planting areas,and Yunnan was the highest,followed by Hainan,and Guangdong was the lowest;The soil organic carbon content in 0-5 years was significantly higher than that in 16-20 years(P<0.05);The content of soil organic carbon was the highest in 10-15 years,and the lowest in 26-30 years;The content of soil organic carbon was the highest in 31-35 years and the lowest in 16-20 years;In different soil layers of the same Forest age,the content of soil organic carbon decreased with the increase of soil depth.Except for individual soil layers,the content of soil organic carbon in shallow soil was higher than that in deep soil.(3)Driving factors of soil organic carbon differences in rubber planting areas of ChinaSoil organic carbon content in rubber planting areas of China is highly correlated with site conditions(altitude,longitude and latitude),rubber tree conditions(coverage,forest age and tree height),and soil nutrients(available phosphorus,available potassium and ammonium nitrogen).Among them,the soil organic carbon content in Yunnan rubber planting area was highly correlated with longitude,coverage rate,p H and available phosphorus content,the soil organic carbon content in Guangdong rubber planting area was highly correlated with altitude,tree height and available potassium content,and the soil organic carbon content in Hainan rubber planting area was highly correlated with forest age and ammonium nitrogen content.In the process of fertilization management of rubber forest,we should pay attention to the balance of various nutrients and environmental factors.(4)Comparative characteristics of soil organic carbon content between rubber plantation and other plantationsBy comparing the rubber forest plot with the control plot(Cinnamomum cassia,pineapple,ecological economic forest,nut garden,grapefruit forest and star anise forest in Yunnan Province);Eucalyptus forest,litchi forest,banana forest and longan forest were selected in Guangdong;The results showed that there was no significant difference in soil organic carbon content between rubber plantation and other plantations(P > 0.05).Among them,the average organic carbon content of rubber forest in Yunnan and Guangdong was slightly higher than that of the control,and that of Hainan was slightly lower than that of the control.The purpose of this study is to understand the differences of soil organic carbon components in different ecological systems,different forest ages,different soil layers and different artificial forests in China.The study on the soil organic carbon components in different areas can provide basic data for improving the soil organic carbon quality and coping with climate change in different regions;The research on the present situation and change difference of soil fertility of rubber forest of different forest age can provide scientific basis for improving soil,planting reasonably and guiding fertilizer formula of rubber trees of different age in rubber planting area;The analysis of organic carbon content in different soil layers in the same planting area can provide reliable data for the vertical change of soil organic carbon components and the exploration of soil surface and deep carbon pool;Comparing the differences between soil indexes in rubber planting area and tropical crop sample land,it can make some contribution to the service and improvement of artificial rubber forest ecosystem,ecological landscape construction and global change.