典型草原不同放牧强度草地土壤健康评价

Soil health assessment of typical grasslands differing in grazing intensity

土壤是草地植被生长的基础,土壤质量的好坏直接影响植被的生长状况,为探究放牧强度对典型草原土壤性能的影响,以呼伦贝尔典型草原为研究对象,选取重度放牧、中度放牧、不放牧草地,对表层0—30 cm土壤的物理、化学、生物等19个指标进行分析,利用主成分分析法选取9个主要贡献指标,利用模糊综合评价法,评价不同放牧强度草地的土壤健康状况。结果显示:(1)放牧强度的增加改变草地土壤的物理化学生物性质,随放牧强度的增加,表层土壤砂粒含量上升,粘粒粉粒含量下降,三种放牧草地30cm深土壤的物理特性差异显著(P<0.05)。(2)土壤中氮、磷、钾、有机质等元素含量变化差异较大,总体显示随深度的增加逐渐增大;土壤中多酚氧化酶、蔗糖酶、脲酶活性退化程度,随深度的增加而逐渐减小,且不放牧草地<中度放牧草地<重度放牧草地。(3)通过主成分分析选取处对土壤变化较为敏感的田间持水量、土壤容重、粉粒、pH值、电导率、全磷、全钾、有机质、脲酶为土壤健康评价指标,进行模糊综合评价,得出重度放牧、中度放牧和不放牧草地的健康系数为0.607、0.674、1。因此,不放牧草地土壤健康状况最好,重度放牧草地土壤健康状况最差,同时适当的将草原重度放牧草地向中度放牧和不放牧草地转变,将有利于草原土壤环境的改善及恢复。

Healthy soil is fundamental for vegetation growth;thus,vegetation growth is affected by soil quality.We studied the Hulun Buir grassland to investigate the effects of grazing intensity on grassland soil quality.The physical,chemical and biological indicators of soil at 0-30 cm depths were analyzed for grasslands that had experienced heavy grazing,moderate grazing and no grazing.Principal component analysis was used to select the nine indexes that made the largest contribution to explaining variation in soil condition.The condition of the grassland soil at different grazing intensities was evaluated using the fuzzy comprehensive evaluation method.Increased grazing intensity altered the physical,chemical and biological properties of grassland soil.As grazing intensity increased,the content of sand on the surface soil increased,and the content of clay decreased.The physical characteristics of soil at a depth of 30 cm among the three grasslands were significantly different(P<0.05).The contents of soil nitrogen,total phosphorus,total potassium and organic matter varied greatly among grasslands depending on the grazing intensity,and the contents of these compounds increased with soil depth.The degradation of polyphenol oxidase,sucrase and urease in soil decreased with soil depth,and degradation of these compounds was highest in heavily grazed grasslands,followed by moderately grazed and non-grazed grasslands.Soil evaluation indexes that were determined to be sensitive to changes in soil condition by principal component analysis included field moisture capacity,soil bulk density,powder,pH,electrical conductivity,total phosphorus,total potassium,organic matter and urease.Fuzzy comprehensive evaluation revealed that the health coefficients of heavily grazed,moderately grazed and non-grazed grassland were 0.607,0.674 and 1,respectively.The health of the soil of non-grazed grassland was the highest,whereas the health of the heavily grazed grassland was the poorest.These findings provide important information for the selection of grazing methods and grassland management practices and demonstrate the benefit of developing adaptable grazing methods.This study provides essential information for the selection of different grazing methods and management practices.