| As an important ecosystem, wetlands have a crucial function in regulating climatic and improving ecological environment. Heilongjiang province is an important wetland distribution area, and it's unique geographical position and climate condition makes its wetland in a high status. Recently, people are more focus on the issue of wetland degradation, "carbon source" and "carbon sink" of wetlands caused by climate change.Therefore,the wetlands of Heilongjiang province was selected for the study of its soil humus content, humus compositions and their influencing factors; the variation rule of soil carbon density and soil organic carbon contents were also studied, to provide scientific data and theoretical support for wetland protection, restoration and scientific management. The main results are as follows:(1)The soil humus carbon content of Heilongjiang province was in significant horizontal and vertical distribution in the order of XiaoXing'an Mountain>Sanjiang Plain>DaXing'an Mountain>Songnen Plain. Besides the Carex schmidtii Meinsh wetland, the wetland humus carbon content decreased with the increasing of the soil depth. The average soil humus carbon content of 0-50cm soil layer was:Larix gmelinii-Betula ovalifolia-Vaccinium uliginosum wetland (229.61 g·kg-1)>Carex schmidtii Meinsh-Deyeuxia angustifolia wetland (138.83 g·kg-1)> Deyeuxia angustifolia wetland (109.25 g·kg-1)>Carex schmidtii Meinsh wetland (89.49 g·kg-1)>Betula fruticosa-Vaccinium uliginosum wetland(87.40 g·kg-1)> Larix gmelinii-Ledum palustre wetland (30.50 g·kg-1)>Phragmites australis-Deyeuxia angustifolia wetland (18.94 g·kg-1)> Phragmites australis wetland (seasonal hydrops plot,9.90 g·kg-1)> Phragmites australis wetland (perennial hydrops plot,4.89 g·kg-1)(2) There was a significant difference in soil humus compositions' content of different area, humin took 51.42%,60.64% of the total carbon in Songnen Plain; total carbon in Sanjiang Plain was mainly humic acid, Phragmites australis-Deyeuxia angustifolia wetland, Carex schmidtii Meinsh-Deyeuxia angustifolia wetland, Deyeuxia angustifolia wetland took 53.04%,35.5%,55.6%,of the total carbon respectively. Both humic acid and fulvic acid were high in the wetland soil of Xiaoxing'an Mountains.There's significant difference in soil humus compositions between wetland types in Daxing'an Mountain.(3)Temperature, rainfall and soil moisture had great influence on humus compositions. Temperature were proportional related to humic acid, and inverse proportional rekated to fulvic acid and humin; rainfall were proportional related to fulvic acid, and inverse proportional related to humin. Soil moisture had higher correlation with humus compositions and lower correlation with soil density, capillary porosity and non-capillary porosity.(4) Organic carbon density was significantly different in different area, appearing as: Sanjiang Plain (18.80～129.49 kg·m-3)> Daxing'an Mountain (38.19～67.92 kg·m-3) >Xiaoxing'an Mountain (36.41～43.99 kg·m-3)>Songnen Plain (7.81～16.27 kg·m-3) Vertical distribution of organic carbon density was most influenced by soil density and organic carbon contents.(5) Organic carbon storage had significant regional difference, higher in Sanjiang Plain (8.13×103～6.985×104 t·km-2) and lower in Songnen Plain (3.41×103～7.06×103 t·km-2) Daxing'an Mountain and Xiaoxing'an Mountain are1.616×104～3.001×104 t·km-2,1.729×104～2.613×104 t·km-2. Sanjiang Plain had a stable carbon storage performance with it's high humic acid content, while Xiaoxing'an Moutntains proned to lose carbon storage with its high humic acid and fulvic acid.The organic carbon in the form of humin in Daxing'an Mountain and Songnen Plain didn't tend to lose, it had little function on improving the soil structure.
|
PDF Full Text Request