民勤绿洲-荒漠过渡带微区土壤水分及粒度特征研究

Soil Moisture and Grain Size Characteristic of Micro-area in Oasis-desert of Minqin

为阐明民勤沙区3种典型微区土壤水分及其粒度特征变化,在其产流区及积水区采用土壤剖面及多点混合取样法取样,供土壤水分及理化性质分析,研究结果表明：（1）3类微区积水区积水痕迹明显且其植被盖度大于产流区。粘土沙障＋梭梭林积水区结皮发育优于产流区,白刺沙包丘间低地及粘土平地与其结果恰好相反。（2）固定白刺沙包丘间低地积水区各层水分优于产流区;粘土平地表层土壤含水量积水区明显好于产流区,而粘土沙障＋梭梭林表层土壤含水量产流区好于积水区。（3）3类微区积水区土壤含水量在20~40 cm之间最低,其中固定白刺沙包丘间低地明显高于粘土平地和粘土沙障＋梭梭林,而对应产流区土壤最低含水量大小及出现深度基本一致。（4）固定白刺沙包丘间低地积水区表层粘、粉粒含量小于产流区,而深层细砂粒含量产流区大于积水区;粘土平地两区土壤组成以粗、细砂粒为主,粘粒在各对应层产流区都好于积水区。粘土沙障＋梭梭林以粗砂粒为主,结构较为单一。可得出结论,微区通过调节降水的分配方式来影响土壤水分及粒度分布进而影响沙地微区植被时空分布。

To clarify the three kinds of micro-area soil moisture and grain size characteristics change inMinqin desert area,mixed soil profile and multi-point sampling method were used in its water runoff area andaccumulated area to analyze soil moisture and grain size characteristic properties.The results showed that：（1）water content and condition of vegetation of water accumulated area were significantly better than that of therunoff area in three types of micro-area,growth of crust of water accumulated area was better than that of waterrunoff area in clay sand barrier ＋ Haloxylon forest,on the contrary,crust of water runoff area grew better thanwater accumulated area in the lowland of Nitraria schobei sandbags and clay plains;（2）the water content ofwater accumulated area was better than that of the runoff area in lowland of fixed Nitraria schobei sandbags,and water content of surface layer of water accumulated area was better than that of the runoff area in clayplains,but the runoff area was better than water accumulated area in clay sand barrier ＋ Haloxylon forest;（3）the low water content of water accumulated area were between 20 to 40 cm,and lowland of Nitraria schobeisandbags was significantly larger than clay plains and clay sand barrier ＋ Haloxylon forest,the correspondingof the runoff area,its water content and soil depth are basically consistent;（4）the contents of clay and silt are large in surface layer of water accumulated area of lowland of Nitraria schobei sandbags,on the contrary,finesand are more in the runoff area;the mainly parts of clay plains were fine sand and coarse sand.Besides,claycontent in the corresponding of layers,the runoff area is better than water accumulated area.Clay sand barrier＋ Haloxylon forest was mainly composed of the coarse sand,but its structure is very simple.In short,the micro-area by adjusting the distribution of precipitation could influence soil moisture and grain size distribution andthe sand area vegetation space-time distribution.