天山北坡绿洲不同土地利用对土壤特性的影响

以天山北坡三工河流域冲积平原型绿洲作为研究区,选择12种土地利用系统作为土地利用方式的具体体现,通过采集不同土地利用系统上层土壤 (0~20 cm) 和下层土壤 (20~40 cm) 样方,分析不同土地利用系统对主要土壤特性的影响。研究结果表明：(1) 土地利用系统对砂、粉砂和粘土粒度分布的影响显著。绿洲土壤砂含量随着土地种植年限增加有降低的趋势,而粉砂和粘土含量有增加的趋势;(2) 绿洲土地利用系统对土壤pH值和养分变异的影响显著。人类强干扰的土地利用系统的土壤养分普遍高于人类影响较弱的土地利用系统,上层土壤养分普遍高于下层土壤,而且随着人类干扰时间的延长土壤养分呈整体增加趋势;(3) 人类活动强干扰的土地利用系统土壤盐分含量低于人类活动影响较弱的土地利用系统;人类活动作用时间长的土地利用系统土壤盐分含量总体低于人类活动作用时间短的土地利用系统;(4) 绿洲土壤总体表现为"碳汇"的趋势,土壤质量逐步得到提高,其最主要的原因在于合理的土地利用与科学的管理方式结合;绿洲土壤的"碳汇"积极响应了减轻温室气体排放的东京协定 。

Effect of Different Land-use Systems on Soil Properties in the Alluvial Plain-oasis in the Arid Land

Taking the alluvial plain oasis as a study case, we have investigated and evaluatedthe oasis soil properties related to different land-use systems during the process of thetransformation of arid desert to oasis. The land-use systems selected consist of an annual cropfield with a tillage history of less than 3 years, annual crop field of 3-6 years, annual cropfield of more than 6 years, perennial crop field of less than 4 years, perennial crop field of4-6 years, perennial crop field of more than 6 years, abandoned farmland of more than 3years, woodland of more than 6 years, ecological forested land, natural shrubbery land, desertsteppe and saline or alkaline field. We deliberately collected 5 soil samples in the differentareas for each land-use system at the topsoil (0-20 cm) and subsoil (20-40 cm). The soilsamples were sent to soil laboratory. We have employed SPSS statistical software to analyzethe soil property data. The results show that: (1) The soils are mainly composed of sand andsilt. Different land use systems significantly affect the sand, silt and clay distributions. Sandtends to decrease with increasing years of land cultivation and silt and clay trend to increasein the oasis soil. (2) Soil pH and nutrients significantly differ with the land-use systems. Soilsof strong human-disturbed land-use systems presented a higher fertility level than those ofother weak human-disturbed land-use systems. Oasis soil nutrients tend to increase with theincreasing years of human disturbance. (3) The effect of land-use systems on soil salinity issignificant. The soils of strong human-disturbed land-use systems have a lower salinity thanthose of weak human-disturbed land-use systems as a whole. The soil salinity usually tends todecrease with the decreasing years of reasonable human disturbance.