不同水土保持植被对典型黑土微团聚体稳定性的影响

Effect of Soil and Water Conservation Vegetation on the Stability of Micro-aggregates in Typical Black Soil Region

以典型黑土区落叶松人工林、水曲柳人工林和草地等水土保持植被以及耕地土壤为研究对象,通过土壤微团聚体分散系数、粒径组成以及不同粒径微团聚体有机碳质量分数的测定计算和分析。结果表明:(1)与耕地相比,所研究的3种水土保持植被均可显著增加(0.05mm<d≤0.25mm)大粒径微团聚体组成比例、降低(d≤0.002mm)小粒径微团聚体组成比例(P<0.05),并表现出乔木植被对增加土壤大粒径微团聚体比例的作用显著强于草地植被(P<0.05);(2)所研究的3种水土保持植被总体上均不同程度地较耕地增加了土壤微团聚体有机碳质量分数,尤其是乔木植被显著增加了土壤中各个粒径的微团聚体有机碳质量分数,且增加幅度显著高于草地植被(P<0.05);(3)水土保持植被均显著降低了土壤分散系数(P<0.05)。可以认为,水土保持植被通过改善土壤微结构和增加微团聚体有机碳质量分数,进而实现增强微团聚体的稳定性,以微团聚体有机碳质量分数增加的贡献大于微团聚体组成的改变。

The stability of soil micro-aggregates from soil and water conservation vegetation in typical black soil region was studied by measuring,calculating and analyzing the dispersion coefficient of soil micro-aggregates,particle size composition of soil micro-aggregates and organic carbon content of soil micro-aggregates with different particle sizes.Three vegetations including Larix gmelini plantation,Fraxinus mandshurica plantation and grassland were selected as test objects,and the cultivated land was as the comparison.The results showed that :(1)Compared with cultivated land,three types of soil and water conservation vegetation can significantly increase the proportion of large-particle size micro-aggregates (0.05 mm< d ≤0.25 mm) in soil,and significantly reduce the proportion of small-particle size micro-aggregates ( d ≤0.002 mm) in soil ( P <0.05),and the effect of arbor vegetation to increase soil big particle size of micro-aggregate proportion significantly higher than the effect of grassland vegetation ( P <0.05);(2)The three types of soil and water conservation vegetation increased the organic carbon content of soil micro-aggregates to varying degrees compared with that of arable land.In particular,the organic carbon content of micro-aggregates of various particle sizes in soil was significantly increased by arbor vegetation,and the increase was significantly higher than that of grassland vegetation ( P <0.05).(3)Soil and water conservation vegetation significantly reduced soil dispersion coefficient ( P <0.05).Therefore,soil and water conservation vegetation can enhance the stability of micro-aggregates by improving soil microstructure and increasing the organic carbon content of micro-aggregates,and the contribution of the increase of organic carbon content of micro-aggregates is greater than that of the change of the composition of micro-aggregates.