长期围封对高寒草地土壤团聚体稳定性和可蚀性的影响

Effects of long-term enclosure on soil aggregate stability and erodibility in Bayinbuluk alpine grassland

为评价长期围封对土壤团聚体稳定性和可蚀性的影响,选择巴音布鲁克高寒草地(高寒草甸、高寒草甸草原和高寒草原)长期围封(围栏设置于1984年)与自由放牧的样地作为研究对象。分析0~5 cm、5~10 cm、10~20 cm和20~30 cm土层中水稳性团聚体组分、平均重量直径(MWD)、几何平均直径(GMD)和土壤可蚀性(K值)。结果表明:(1)MWD最小值出现在高寒草甸0~5 cm土层自由放牧处理下,其数值为1.75 mm。高寒草甸和高寒草甸草原围封和自由放牧下20~30 cm土层的MWD和GMD没有显著性差异(P>0.05),而高寒草原差异显著(P<0.05)。(2)高寒草原放牧处理10~20 cm土层K值最高为0.136,在所有处理中抗侵蚀能力最弱。(3)冗余分析发现,全钾、全磷、pH和土壤有机碳SOC是影响土壤可蚀性K值和MWD的最主要因素。(4)巴音布鲁克高寒草地0~10 cm土层以>2mm大团聚体为主,长期围封导致0~10 cm土层土壤团聚体稳定性更强;且草地类型、围封和土层均对土壤团聚体稳定性和可蚀性有着显著的影响,说明长期围封可以提高土壤团聚体的水稳定性和抗侵蚀能力。

To evaluate the effects of long-term enclosure measures on the stability and erodibility of soil aggregates,the grassland(alpine meadow, alpine meadow steppe, and alpine steppe) with long-term enclosure(fenced in 1984) and free grazing were selected as the research objects. The composition, mean weight diameter(MWD),geometric mean diameter(GMD), and soil erodibility(K value) of water-stable aggregates in 0-5, 5-10, 10-20,and 20-30 cm soil layers were analyzed. The results showed that:(1) The minimum MWD value appeared in the 0-5 cm soil layer of the alpine meadow under free grazing treatment(1.75 mm). No significant difference was observed in the MWD and GMD of 20-30 cm soil layer under the enclosure and free grazing in an alpine meadow and alpine meadow steppe(P > 0.05), while the difference in alpine steppe was significant(P < 0.05).(2) The K value of 10-20 cm soil under free grazing was 0.136, so the anti-erosion ability was the weakest in all treatments.(3) The redundant analysis found that the changes in total potassium, total phosphorus, and pH were the most important factors affecting soil K value, and soil organic carbon was the most important factoraffecting MWD.(4) The 0-10 cm soil layer of Bayinbuluk alpine grassland was dominated by >2 mm macroaggregates.The long-term enclosure caused stronger stability of soil aggregates in the 0-10 cm soil layer. Moreover,grassland type, enclosure, and soil layer significantly affect the stability and erodibility of soil aggregates. This indicates that long-term enclosure could improve the soil aggregates’ water stability and erosion resistance.