青藏高原典型沙化区草地土壤质量评价

为了探究青藏高原沙化区草地土壤质量变化,采用主成分分析法筛选具有代表性的土壤质量指标构建最小数据集,计算土壤质量指数SQI(Soil Quality Index),评价了青藏高原海晏县、共和县、贵南县3个典型沙化区不同沙化程度下的土壤质量变化特征。结果表明:(1)随着沙化程度的减弱,3个典型沙化区草地的地上生物量均值由0增大至(0.8±0.18)kg/m²; 土壤有机质、全氮、全钾、全磷、速效钾、速效磷、碱解氮等养分含量增大,土壤阳离子交换量(CEC)增大了87.28%; 土壤容重减小了33.62%;(2)3个典型沙化区内不同沙化程度下,贵南县森多镇土壤质量最好,其次为共和县铁盖乡,海晏县三角城镇土壤质量最差;(3)最小数据集与全数据集的土壤质量指数呈现极显著相关关系,表明采用最小数据集法代替全数据集法评价典型区沙化草地土壤质量是行之有效的。综上所述,沙化区草地的土壤质量随沙化程度的加剧逐渐降低,不同沙化区草地土壤质量存在空间差异性。

Evaluation of Grassland Soil Quality in Typical Desertified Areas of Qinghai-Tibet Plateau

In order to explore the changes of grassland soil quality in the desertification area of the Qinghai-Tibet Plateau,the principal component analysis method was used to screen the representative soil quality indexes,construct the minimum data set,calculate the soil quality index SQI(soil quality index),and evaluate the characteristics of soil quality changes under different degrees of desertification in three typical desertification areas of Haiyan County,Gonghe County and Guinan County of the Qinghai Tibet Plateau.The results show that:(1)with the decrease of desertification degree,the mean aboveground biomass of grassland in three typical desertification areas increased from 0 to(0.8±0.18)kg/m²;the contents of soil organic matter,total nitrogen,total potassium,total phosphorus,available potassium,available phosphorus and alkali hydrolyzable nitrogen increased,and the soil cation exchange capacity(CEC)increased by 87.28%;the soil bulk density decreased by 33.62%;(2)in the three typical desertification areas,under different desertification degrees,the soil quality in Senduo Town,Guinan County is the best,followed by Tiegai Township,Gonghe County,and the soil quality in Sanjiaocheng Town,Haiyan County is the worst;(3)there is a very significant correlation between the soil quality index of the minimum data set and the full data set,which shows that it is effective to use the minimum data set method instead of the full data set method to evaluate the soil quality of sandy grassland in typical areas.In conclusion,the soil quality of grassland in desertification areas gradually decreases with the aggravation of desertification degree,and there are spatial differences in soil quality of grassland in different desertification areas.