Role of Collembola in Carbon Transformation--A13C-labelling Study
Terrestrial carbon cycle is one of the key issues in the world. Soil fauna play essential roles in soil ecosystem which is the largest terrestrial carbon sink. However, both the contributions of soil fauna to carbon transformation and the underlying mechanisms are still unclear. The isotope technology provided an useful method to quantify the key processes in soil food web and material cycling. In this study,13C-labeled leaf litter was used to investigate the effect of the Collembola (Folsomia Candida) on carbon transformation in laboratory microcosms. Three treatments were set up: (1) soil (control, S), (2) soil and labeled litter (SL), and (3) soil, labeled litter and Collembola (SLC). Each treatment has four replicates. These microcosms were destructively sampled on day 7, 21, 63 after the experiment initiation. The results showed that litter-derived C was incorporated into soil biota rapidly. The originalδ13C values of Collembola was -9.91‰±0.08‰, and it reached 522.70‰ after 7 days of incubation indicating that Collembola could efficiently assimilate this newly introduced litter-derived C. Similarly, theδ13C values in PLFAs increased significantly, especially at the initial experimental stage. In addition, the presence of Collembola significantly promoted the PLFAsδ13C suggesting that Collembola could accelerate the microbial assimilation of litter carbon. Unexpectedly, treatment SLC exhibited significantly lowerδ13C values than treatment SL. This may indicate that the presence of Collembola stimulated the release of newly metabolized litter C. Both of the treatments stimulated CO2 flux significantly. By C isotope analysis, over 85% of the mineralized C derived from litter at the initiation state (21 days), demonstrating that new C from fresh litter tended to release back to atmosphere with active soil biota. Thereafter, the contribution of soil-derived C to the CO2 emission increased. This study proved that new C from litter could participate in soil C cycling rapidly, especially in systems with active soil biota. While, the newly introduced litter C was also readily to be respired as CO2. In spite of the small size, Collembola had a priming effect on microbes in the litter-soil environment and, thus, contributed to the functioning of soil food web.
国家科技期刊平台
NSTL
万方数据
维普
