Effects of draining for forestation on carbon storage of wetland ecosystem in Daxing'an Mountains of northeastern China.

The distribution pattern of ecosystem carbon storage ( vegetation, litter, soil) and net carbon sequestration of wetland larch plantation along the wetland ecotone environmental gradients (0-400 m) were studied by transect measuring and comparison methods in Daxing'an Mountains of northeastern China, further compared with the corresponding habitats of natural wetlands so as to reveal the effects of wetland draining for forestation on its carbon storage and net carbon sequestration. The results showed that: 1)the carbon storage of vegetation from larch plantation and the natural wetland (6.49-59.95, 3.24-78.97 t/ hm2 ) both took on an increasing trend along the ecotone environmental gradients, and draining for forestation made it increase by 43.9%~241.0% at 100-300 m habitats significantly (P 0.05), but decrease by 24.1% at 300-400 m habitat remarkably (P 0.05); 2)the carbon storage of litter from both (1.61-4.69, 1.51-4.34 t/ hm2 ) also took on an increasing trend, and draining for forestation made it increase by 84.1% at the 100-200 m habitat remarkably (P 0.05); 3)the carbon storage of soil (163.03-308.68, 192.09-382.91 t/ hm2 ) was higher at the 0.100 m habitat, lower at 第5 期崔巍等: 排水造林对大兴安岭湿地生态系统碳储量的影响 300-400 m habitat on the wetland larch plantation ecotone and took on a decreasing trend on the natural wetland ecotone respectively, and draining for forestation made it decrease by 19.4%~43.4% significantly at 0.300 m habitats relative to the natural wetland (P 0.05); 4)the carbon storage of ecosystem (227.68-316.78, 275.40-387.67 t/ hm2) was higher at 0.100 m habitat, lower at 100-400 m habitats on the wetland larch plantation ecotone and higher at 0.300 m habitats, lower in 300-400 m habitat on the natural wetland ecotone respectively, and draining for forestation made it decrease by 18.3%-31,0% at the 0.300 m habitats remarkably relative to the natural wetland (P 0.05); 5)the net primary productivity and annual carbon sequestration (3.67-10.34, 8.03-10.77 t/ (hm2·a); 1.59-4.87, 3.24-5.07 t/ (hm2·a)) took on an increasing trend and constant trend along the ecotone environmental gradients respectively, and draining for forestation made both decrease by 54.3% and 50.9% significantly at 0-100 m habitat of the ecotones (P 0.05), but had no remarkable influences at other habitats ( -19.3%~18.7% and -20.1%~17.3%, P 0.05). Therefore draining for forestation lowers the carbon storage of wetland ecosystem remarkably, but has relatively weak effects on carbon sequestration.