松嫩平原黑土土壤有机碳库的估算及其影响因素

Evaluation on Soil Organic Carbon Pool and Affecting Factors in Phaeozem Region in Songnen Plain

松嫩平原黑土总面积约5.90×106hm2,对上述黑土区9个市县34个土壤剖面102份土壤样品的有机碳进行了分析,并对其有机碳密度、储量进行了数理统计。结果表明,松嫩平原黑土有机碳平均含量较高为14.14g·kg-1,变幅在11.29～17.31g·kg-1之间。有机碳密度平均值为23.49kg·m-2,变幅在17.24～30.43kg·m-2之间,与全国其他各种土壤类型比较,黑土有机及其碳密度均较高,反应出黑土具有深厚有机质累积的特征。松嫩平原黑土机碳储量约为14.12×108t,是比较大的土壤有机碳库,约占全国陆地土壤总有机碳储量的1.53%。如按统计的877.63×106hm2国土面积计算,松嫩平原黑土面积仅占统计面积的0.67%。黑土分布区内不同地域黑土有机碳密度分布与温度关系最为密切,表现为与纬度正相关,与≥10℃的积温负相关,尚未发现黑土分布区内有机碳密度分布与降水存在相关关系。

The total area of black soils region in Song'nen Plain is 590×104 h m2. The content of soil organic carbon, its density and deposition were research ed from 102 soil samples in 34 soil sections at 9 cities. The results showed tha t the content of organic carbon in black soils in Song'nen Plain was 14.14 g·kg-1 on average, ranged from 11.29 g·kg-1 to 17.31 g·kg-1, the density of org anic carbon was 23.49 kg·m-2 on average, ranged from 17.24 kg·m-2 to 30.43 k g·m-2, which suggested that the content and density of organic carbon in black soils were both comparatively higher than in other types of soil, and organic m atter accumulated deeply in black soils. It was estimated that this region depos ited a black soil organic carbon (SOC) pool of 1.412 billion tons that contribut ed to 1.53%of that of the whole country, though the area of the black soils reg ion in Song'nen Plain occupied only 0.67%of the total area of our country. Fact ors such as moisture, temperature, terrain affected the density of organic carbo n in different areas. A very significant correlation was found between the densi ty of organic carbon and temperature in black soil region, and the density incre ased with the latitude ascending, but decreased with accumulated temperature (≥ 10 ℃) increasing. The decomposition speed of organic matter was slow in high al titude area since the decreased annual average temperature and accumulated tempe rature and the limited activities of microbe, but the organic matter accumulated largely for its short and hot summer and the thickest plant with developed root system that benefited the accumulation of organic carbon in black soils. No sig nificant correlation was obtained between the density of SOC and rainfall. The m oderate rainfall there advanced the development of plant and its root system and was helpful for the return of litter and root to soils, so the organic matter c ould form and then accumulate in soils. The effect of rainfall on density of org anic carbon was not observed within 400～600 mm that concentrated during April-September and could not restrict the development of plant.