Effects Of Afforestition In Drained Wetland On Carbon Storage Of Wetland Ecosystem In Daxing’an Mountain In China

The practice of afforestition in drained wetland have been carried out since the80’s of the last century in Northeast China, so far the area of the wetland larch plantation is about hundreds of thousands of hectares. Correlational research really shows that one hand wetland drainage can improve local habitat area (upper habitat transition with water environmental gradients) stand productivity and volume, on the other hand, caused by water drainage, the decline of the water level and the rise of the temperature causes the acceleration of soil peat decomposition process, the peat layer of wetland is disappears in whole or in part, the emissions of methane decreased or changed into the sink. However, the influence of draining for forestation on the carbon storage of the whole ecosystem is still not very clear.This paper, which made use of the sample investigation and comparative analysis method, studied the the vegetation carbon storage, carbon storage in litter, soil carbon storage and net primary productivity and annual net carbon sequestration of formation of drainage in25years old larch plantation in wetland ecotone along different habitats (underpart0～100m, lower part100～200m, upper part200～300m and upside300～400m) in Daxing an Mountains, revealed the variation regularity of its ecosystem carbon storage and annual net carbon sequestration along transition zone water environmental gradients, and by the comparative analysis with natural wetland of corresponding habitat area, reveal the drainage afforestation effects on carbon storage of wetland ecosystem and carbon sequestration capacity. The results showed that:1. the carbon storage of vegetation from larch plantation and the natural wetland (6.49±1.35～59.95±0.51tC/hm2,3.24±0.05～78.97±5.22tC/hm2) both took on an increasing trend along the water environmental gradients, and draining for forestation made ecotone increase by43.9%～241.0%at the100～300m habitats significantly (p<0.05), but decrease by24.1%at the300～400m habitat remarkably (p<0.05) relative to the corresponding natural wetland.2. the carbon storage of litter (1.61±0.54～4.69±0.40tC/hm2,1.51±0.14～4.34±1.38tC/hm2) also took on an increasing trend, and draining for forestation made ecotone increase by84.1%at the100～200m habitat remarkably (p<0.05).3. the carbon storage of soil (163.03±2.41～308.68±10.35tC/hm2,192.09±61.66～382.91±48.59tC/hm2) was higher at the0～100m habitat, lower at the300-400m habitats on the wetland larch plantation ecotone and took on a decreasing trend on the natural wetland ecotone respectively, and draining for forestation made ecotone decrease by19.4%～43.4% significantly at the0～300m habitats relative to the natural wetland (p<0.05).4. The carbon storage of ecosystem (227.68±2.63～316.78±8.49tC/hm2å'Œ275.40±72.20～387.67±46.41tC/hm2) was higher at the0～100m habitat, lower at the100～400m habitats on the wetland larch plantation ecotone and higher at the0～300m habitats, lower in the300～400m habitat on the natural wetland ecotone respectively, and draining for forestation made it decrease by18.3%～31.2%at the0～300m habitats remarkably (p<0.05). Therefore, the drainage after planting25years significantly reduced the carbon storage of the middle and under part of the habitat areas in transition zone in Daxing an Mountains, and is not conducive to maintaining long-term carbon sequestration of wetland.5. The net primary productivity and carbon sequestration (3.67±0.81～10.34±0.81,8.03±2.14～10.77±1.20t/hm2·a;1.59±0.34～4.87±0.61,3.24±0.86～5.07±.61tC/hm2·a) took on an increasing trend or constant trend along the ecotone water environmental gradients respectively, and draining for forestation made both decrease by54.3%and50.9%significantly at the0～100m 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 lowered the reduced the carbon sequestration of the underpart of the habitat areas in transition zone remarkably in Daxing an Mountains, but had the relatively weak effects on the others.