宁南黄土区植被恢复方式对土壤粒度特征的影响

Effects of Vegetation Restoration Methods on Soil Particle Size Characteristics in Loess Region of Southern Ningxia

[目的]研究宁南黄土区不同植被恢复方式下的土壤粒度特征,旨在为更有效地指导该区域土壤资源的可持续发展和生态环境保护提供科学依据。[方法]采用野外标准化方法采集0—100 cm土壤样品,利用Mastersizer 3000型激光粒度仪测定了小流域9种不同植被恢复方式(山杏林、山桃林、沙棘林、柠条林、山杏柠条林、山杏沙棘林、坝地、苜蓿地、撂荒地)216件样品,通过福克和沃德公式计算出平均粒径、标准偏差、偏度、峰度等土壤粒度参数。[结果](1)不同植被恢复方式下的粒度组成均以粉粒和极细砂为主,以粉粒含量在各粒度分级中所占比例最大。黏粒、粗砂、极粗沙和中砂含量分层整体趋于稳定,随土层深度的增加变化不大。粉粒、极细砂和细砂含量均随土层深度增加变化起伏较大,各层段表现出不同的变化趋势。(2)不同植被恢复方式下各粒级变异系数的变化规律基本一致,黏粒的变异系数最高,其次为砂粒,粉粒最小。(3)土壤平均粒径表现为:山杏×柠条林>沙棘林>山桃林>柠条林>山杏林>苜蓿地>山杏×沙棘林>撂荒地>坝地。撂荒地、山桃林和柠条林的分选性明显优于其他立地,沙棘林的分选性最差。[结论]不同植被恢复方式的土壤粒度分布主要受到植被类型及人类活动扰动等主要因素的影响。

[Objective]In order to provide a scientific basis for more effectively guiding the sustainable development of soil resources and ecological environmental protection in the loess region of Southern Ningxia Hui Autonomous Region,soil particle size characteristics under different vegetation recovery patterns were studied.[Methods]Field standardized soil samples(0—100 cm)were collected,and 216 samples from nine different vegetation restoration methods(Prunus armeniaca forest,Amygdalus davidiana forest,Hippophae rhamnoides forest,Caragana korshinskii forest,C.korshinskii×P.armeniaca forest,P.armeniaca×H.rhamnoides forest,dam land,alfalfa land,and abandoned land)were measured with a Mastersizer 3000 laser particle size analyzer.The average particle size(M Z),standard deviation(δ),skewness(SK),and kurtosis(K G)were calculated by the Fokker and Ward formula.[Results]①Under different vegetation recovery patterns,the main particle size components were silt(0.002~0.05 mm)and very fine sand(0.05~0.1 mm),and the proportion of silt content in each particle size classification was the largest.The contents of clay,coarse sand,very coarse sand,and medium sand in different vegetation restoration methods tended to be stable,and changed little with increasing soil depth.The content of silt,very fine sand,and fine sand fluctuated greatly with increasing soil depth,and each layer showed different trends.②The variation of the coefficient of variation of each particle size was basically the same under different vegetation restoration methods.The coefficient of variation of clay was the highest,followed by sand and silt.③The average soil particle size followed the order of P.armeniaca×C.korshinskii forest>H.rhamnoides forest>A.davidiana forest>C.korshinskii forest>P.armeniaca forest>alfalfa land>P.armeniaca×H.rhamnoides forest>abandoned land>dam land.The sorting ability of abandoned land,A.davidiana forest,and C.korshinskii forest was better than that of other sites,with H.rhamnoides forest being the worst.[Conclusion]Soil particle size distribution in different vegetation restoration methods was mainly affected by utilization mode,vegetation type,and human activity disturbance.