祁连山青海云杉(Picea crassifolia)林土壤有机碳与化学性质的相互关系

通过对祁连山大野口流域的青海云杉林大样地进行土壤剖面取样, 分析了样地土壤有机碳与pH值、养分和阳离子交换量等基本化学性质的变化规律及其相互关系. 结果表明: 随土层深度不断增加, 土壤有机碳含量逐渐减小, 在20～30 cm以下趋于稳定(P > 0.05); 土壤pH值不断增大, 仅在0～10 cm与10～20 cm差异显著(P<0.05); 土壤全氮、速效氮、全磷和阳离子交换量不断减小, 全氮含量在30～40 cm以下趋于稳定(P > 0.05), 速效氮含量变化剧烈(P<0.05), 全磷含量差异性不显著(P > 0.05), 阳离子交换量与有机碳含量变化规律相同; 土壤速效磷、全钾和速效钾含量没有明显的变化规律, 速效磷和全钾含量差异性不显著(P > 0.05), 速效钾含量仅在0～10 cm与10～20 cm差异显著(P<0.05). 土壤有机碳与全氮、速效氮、全磷、速效磷、速效钾和阳离子交换量之间呈极显著和显著正相关, 与土壤pH值和全钾含量之间呈极显著和显著负相关. 土壤有机碳与其他基本化学性质的回归方程具有较高精度(R²=0.793), 影响土壤有机碳含量的主要化学因子依次为土壤阳离子交换量、速效钾和全磷含量.

Relationship between soil organic carbon content and chemical properties of Picea crassifolia forest in the Qilian Mountains

Soil samples were taken from soil profiles of Picea crassifolia forest in a large sample plot in Dayekou basin of the Qilian Mountains and analyzed to study the changes of basic chemical properties and the relations between soil organic carbon content and pH value, soil nutrients, cation exchange capacity. The results show that soil organic carbon content gradually decreases with depth and begins to stabilize (P>0.05) at the depth below 20-30 cm; soil pH value gradually increases with depth, with significant difference (P<0.05) only between 0-10 cm depth and 10-20 cm depth; soil total nitrogen, available nitrogen, total phosphorus and cation exchange capacity gradually increase with depth; total nitrogen content below 30-40 cm becomes stable (P > 0.05); available nitrogen content changes dramatically (P<0.05); total phosphorus content difference is not significant (P>0.05); the variation of cation exchange capacity is same as organic carbon content; soil available phosphorus, total potassium and available potassium content have no obvious changing rule; available phosphorus and total potassium content has no significant difference (P>0.05); available potassium content has significant difference only between 0-10 cm and 10-20 cm depths (P<0.05). Correlation analysis results show that there are highly significant positive or significant positive correlations between soil organic carbon content and total nitrogen, available nitrogen, total phosphorus, available phosphorus, available potassium and cation exchange capacity; there are very significant and significant negative correlations between soil organic carbon content and soil pH, total potassium content. The regression equations have high precision between soil organic carbon content and other basic chemical properties (R²= 0.793); the main chemical factors affecting soil organic carbon content are soil cation exchange capacity, available potassium and total phosphorus content.