Soil Carbon Budgets Of Rubber Plantations Ecosystems In The Western Region Of Hainan

Carbon (C) element is not only an important part of the land surface living organisms, but also to participates in one of the most active elements of terrestrial biogeochemical cycling. Terrestrial ecosystem carbon balance and carbon storage and distribution play a vital role in global biogeochemical cycles. Forest soil carbon pool is an important part of the terrestrial carbon pool. With the clean development mechanism afforestation and reforestation carbon sequestration projects (CDM-ARP) mechanism for the implementation, The forest carbon sequestration industry more subject to the attention of the world. In recent five years, the Ministry of Agriculture and natural rubber seed subsidies to promote China’s rubber plantation acreage has expanded each year, Rubber plantation as one of the largest plantation system of China’s tropical regions, while having an economic value, both ecological value, to study the tropical area of rubber plantation ecosystem carbon budget to forest ecosystem carbon biogeochemical cycles process has important theoretical and practical significance. Therefore, this research through different forest age-class rubber plantation soil profile organic carbon content measured, estimate soil organic carbon storage; Situ continuous monitoring of rubber plantation litter enter the total carbon; infrared gas analyzer in situ continuous observation rubber plantation soil respiration and soil respiration component distribution status. Fully understand the environment of rubber planting soil carbon budget change status to better understand the environmental factors affecting soil carbon balance of payments, the scientific evaluation of the effectiveness of the rubber plantation carbon sinks, to provide basic data for the trade of government decision-making and carbon sinks; And to ascertain the feasibility of measures to improve the rubber plantation ecosystem soil organic carbon, and ultimately provide the basic data support for the establishment of the trade of rubber plantation ecosystem carbon source/sink.The main results and conclusions are summared as follows:(1)The content of soil organic carbon (SOC) was6.20～14.36g·kg-1for rubber plantation ecosystems at stand age of5a,10a,19a and33a. Rubber plantation soil organic carbon in the carbon content gradually decreased with the increase in the depth of the soil layer, In0～60cm each layer of soil organic carbon content of the significant difference In addition to stand age33a. Other same plantation age glue for no significant difference between different soil layer. Different rubber plantation in the same soil layer plantation age between soil organic carbon content significantly different. The soil organic carbon focused on0～30cm soil layer. The carbon stock of soil organic carbon in5a,10a,19a and33a rubber plantation were76.85t·hm-2、74.48t·hm-2.81.74t·hm-2and85.31t·hm-2respectively. The soil texture, litter content accumulation and decomposition, forest age size and glue Lin management may be influence rubber plantation soil organic carbon accumulation of the main factors.(2)Rubber plantation litter size for the carbon content components performance: Breeding> leaves> branch components> other. The carbon content of litter components in no significant difference between adjacent forest age.The carbon content of litter collected from5a,10a,19a and33a Rubber plantations were2.081t·hm-2,2.677t·hm-2,3.106t·hm-2and3.583t·hm-2respectively. No significant difference between the different plantation age. The carbon of litter in return with plantation age level is increased(3) The Soil respiration rate (Rs) of day and night with obvious change at stand age of5a,10a,19a and33a. The difference of the forest during the growing season, all plastic soil respiration rate changes in peak and valley and peak time nor the size of the same. The rubber forest Rs average at stand age of5a,10a,19a and33a were1.91μmol·m-2·s-1,1.48μmol· m-2·s-1,1.3μmol·m-2·s-1and1.73μmol·m-2·s-1respectively.The soil respiration rate of various components in the rubber plantations was in the order of Heterotrophic respiration rate> Respiration of roots rate> Respiration of litter layer rate> Respiration of mineral soil rate. Different rubber plantation soil ecological system plantation age with soil respiration rate between temperature and humidity has significantly (p>0.05) of the index correlation, and soil humidity index relevance not significant (p<0.05).(4) The soil respiratory rate (Rs) in different growth is obviously season (months) change pattern at stand age of5a,10a,19a and33a. The respiratory rate of maximum in august. The minimum appeared in november and December.The annual released carbon from soil respiration in the five age group rubber plantions was calculated as10.03t·hm-2、10.34t·hm-2、11.96t·hm-2、11.09t·hm-2. Different rubber plantation soil ecological system plantation age breathing mutual difference was not significant. The soil respiration emissions size in the rubber plantations was in the order of Heterotrophic respiration> Respiration of roots> Respiration of litter layer> Respiration of mineral soil.(5) The carbon stock of soil organic carbon in four plantation ages were74.48t·hm-2～85.31t·hm-2form rubber plantation ecology soil carbon balance analysis0-60cm soil layer. The Litter years carbon net increment was2.08t·hm-2a-1～3.58t·hm-2a-1. The Soil total carbon emissions in respiration was10.03t·hm-2～11.96t·hm-2. Glue for volume in66t·hm-2above at the stand age of5a,10a,19a and33a. It is obvious that rubber plantation soil ecological system is preferably carbon function.In view of the above mentioned, this study aims to explore the rubber plantation ecology systems based on field long-term observation data to estimate rubber plantation ecology system carbon balance. To be able to reaserch rubber plantation in ecological system in China and in carbon function research tropical area rubber plantation ecology systems carbon cycle studies provides some basic research.