Components of Soil Respiration and Its Monthly Dynamics in Rubber Plantation Ecosystems

Our objective was to quantify four components and study effect factors of soil respiration in rubber plantation ecosystems. Providing the basic data support for the establishment of the trade of rubber plantation ecosystem carbon source/sink. We used Li-6400 (IRGA, Li-COR) to quantitate four components of soil respiration in rubber plantation ecosystems at different ages. Soil respiration can be separated as four components: heterotrophic respiration (Rh), respiration of roots (Rr), respiration of litter layer (Rl) and respiration of mineral soil (Rm). The soil respiration rate (Rs) showed significant seasonal variation. The maximum soil respiration rate of the whole year appeared in August, and the minimum in November or December. The components of soil respiration rate order showed as: heterotrophic respiration>respiration of roots>respiration of litter layer>respiration of mineral soil. The soil respiration rate was highly significant correlation (p<;0.01, Q10=1.13~2.37) with 0~10 cm soil temperature in dry season, and significant correlation (p<;0.05, Q10=1.10~1.77) with 0~10cm soil temperature in wet season. And soil respiration rate was not significant correlation with soil water content of 5 cm (p≥0.05). The soil respiration components of four kinds forest ages accounted for the percentage contribution to the flux of annual carbon emissions (Rs) as: Rh: 35.28~52.75%, Rr: 21.73~39.97%, Rl: 17.13~19.63%, Rm: 6.605~10.27%%, respectively. The soil respiration rate carbon flux of 5a, 10a, 19a and 33a respectively were 10.03, 10.34, 11.96 and 11.09 t·hm-2·a-1. And the annual carbon flux of soil respiration increased with stand ages increasing in rubber plantation ecosystems.