乌兰布和沙漠绿洲农田不同土地利用方式地表风蚀特征研究

Wind Erosion Characteristics of Oasis Farmland Surfaces Under Different Land Uses in Ulan Buh Desert

土壤风蚀是干旱地区绿洲农田开发的一个突出生态问题,如何针对不同的立地单元采取保护性措施是人们长久以来关注的重点。本文选择乌兰布和沙漠绿洲农田流沙地、沙质耕地、黏质耕地、撂荒耕地及留茬地5种典型土地利用方式,对其风速特征、地表蚀积量进行野外原位测定,并分析了不同下垫面的地表粗糙度和沉积土壤粒径特征。结果表明:研究区土壤颗粒组成以细砂含量占主导地位,粉粒、中砂与粗砂含量相对较低。与对照相比,各土地利用方式均能有效增加地表粗糙度,表现为:留茬地(0.32 cm)>撂荒耕地(0.29 cm)>沙质耕地(0.25 cm)>黏质耕地(0.19cm)>流沙地(0.02 cm)。土壤风蚀深度整体表现为流沙地>沙质耕地>撂荒耕地>黏质耕地>留茬地,5种利用方式下,留茬地风蚀程度最轻,风蚀深度仅为0.04 cm/d,分别较流沙地、沙质耕地、黏质耕地及撂荒耕地降低了99.03%、96.83%、94.29%与90.24%。因而,留茬地具有较好的防风蚀效益,是一种值得推广的土壤风蚀防治措施。

Soil wind erosion is a prominent ecological problem in the sustainability of oasis farmland in arid areas, therefore, how to take reasonable protective measures against different farmland units is a key concern in arid areas for a long time. In this paper, five typical land use types of shifting sandy land （SSL）, sandy arable land （SAL）, clayey arable land （CAL）, abandoned grassland （AGL） and stubble land （SL） of oasis in Ulan Buh desert were selected, wind speed, surface erosion and deposition, surface roughness and soil particle size distributions （PSDs） were analyzed. The results showed that fine sand was dominant in soil PSDs of all land use types, and the contents of clay sand and coarse sand were relatively low. Compared with SSL, other land use types effectively increased surface roughness, which were in an order of SL （0.32 cm） 〉 AGL （0.29 cm） 〉 SAL （0.25 cm） 〉 CAL（0.19 cm）〉 SSL （0.02 cm）. The depths of soil erosion were in an order of SSL〉 SAL〉 CAL〉 SL. SL was the slightest in wind erosion degree with a wind erosion depth only of 0.04 crn/d, decreased by 99.03%, 96.83%, 94.29% and 90.24% compared with those of SSL, SAL, CAL and AGL, respectively. Thus, stubble land is an effective measure in preventing and controlling soil wind erosion due to its significant wind-intercepting efficiency.