贵州西部4种林型土壤有机碳及其剖面分布特征

在气候变化背景下,森林土壤碳库已成为全球碳循环研究重点之一。以贵州西部桦木（Betula luminifera H.Wilk.）、柳杉（Cryptomeria fortunei Hooibrenk ex Otto et Dietr.）、华山松（Pinus armandii Franch.）和杉木（Cunninghamia lanceilata（Lamb.）Hook.）4种主要森林类型为对象,对其土壤有机碳、碳密度及其垂直分配特征等进行了研究。结果表明：4种林型土壤有机碳含量和碳密度均表现为华山松林（51.09 g.kg-1,30.56 kg.m-2）〉杉木林（39.47 g.kg-1,22.97 kg.m-2）〉柳杉林（37.49g.kg-1,21.00 kg.m-2）〉桦木林（36.31 g.kg-1,20.13 kg.m-2）,华山松林土壤有机碳含量和碳密度显著大于其它三种林型,而另外三种林型间差异不明显;4种林型土壤有机碳含量和碳密度均随土层深度增加而逐渐降低,土壤有机碳含量均为0-10 cm最大,分别是剖面均值的1.45-1.61倍,而0-20 cm层土壤碳密度占整个土壤剖面的32.69%-38.08%,显著高于其他各层,大于20 cm的土层中,各层间的变化较小,土壤碳密度具有一定程度的表聚性;4种林型土壤有机碳含量与土壤pH均表现极强的负相关,与土壤全N和碱解N均表现极强的正相关,与全P、速效P、全K、速效K和阳离子交换量的相关性不尽一致,建立的方程具有较高的回归精度,土壤N和P状况对4种林型土壤有机碳含量有重要影响。

Soil organic carbon and its distribution characteristics in the soil profile for four forest types in west Guizhou

The carbon bank of the forest soil has become one of the key research subjects concerning global carbon cycle in the context of global climate change. Taking the 4 major forest types in West Guizhou composed of Betula luminifera, Cryptomeria fortuneL Pinus armandii and Cunninghamia lanceolata as the research subjects, this paper studied the organic carbon contents of the soil, the density and the vertical distribution characteristics of the organic carbon. The results indicated that the organic carbon contents in the forests of Pinus armandiL Cunninghamia lanceolata, Cryptomeria fortunei and Betula luminifera were respectively 51.09 g＇kg-1, 39.47 g-kgl, 37.49 g.kgl, 36.31 g.kgl and the carbon density was respectively 30.56 kg＇m2, 22.97 kg.m-2, 21.00 kg.m-2 and 20.13 kg.m-2, uniformly showing the descending order that Pinus arma.ndii 〉 Cunninghamia lanceolata 〉 Cryptomeria fortune 〉 Betula luminifera, and the organic carbon contents as well as the carbon density of the soil in the forest of Pinus armandii were strikingly greater than those of the other 3 forests, among which the difference was not so distinct. Both the organic carbon contents and carbon density of the soil decreased gradually with the deepening of the soil in all the 4 forests and the organic carbon contents were the highest in the 0-10 cm-deep soil, as 1.45-1.61 times high as the average values of the whole soil profile, while the carbon densities in the 0-20 cm-deep soil accounted for 32.69%-38.08% of the whole soil profile, prominently higher than those of the other soil depths. The carbon densities between different soil depths from below 20 era-deep soil did not differ so much, and such characteristics indicated the soil carbon was more or less concentrating on the surface of the soil. For all the 4 forest types, there were strong negative correlations between the soil carbon contents and the pH values of the soil, and strong positive correlations between the soil carbon contents and total N as well as alkaline hydrolysis N, and various correlations between the soil carbon contents and total P, quick-acting P, total K, quick-acting K and base exchange capacity. There was high accuracy concerning the established regression equations, and the contents of N and P in the soil had great impact on the carbon contents of all the 4 forest soil.