土地利用变化对鄂尔多斯高原周边地区沙尘暴的影响

以鄂尔多斯高原周边地区为例 ,研究土地利用变化对沙尘暴的影响 ,建立了多年平均沙尘暴日数与沙漠化土地面积百分比之间的关系。该关系表明 ,当沙漠化土地面积百分比Rd大于 30 %以后 ,沙尘暴日数随Rd的增大而急剧增加。年均沙尘暴日数与耕地面积和大风日数之间的回归方程 ,结果表明 ,耕地面积减少和大风日数减少对沙尘暴减少的贡献率分别为5 9 7%和 4 0 3%。通过在干旱、半干旱脆弱生态条件下的地区进行土地利用结构调整和退耕还草 ,恢复草原生态系统 ,可以在一定程度上减低沙尘暴发生的频率。

Sand-dust storms in the Erdos Plateau and neighboring areas as influenced by land desertification

Occurrence of sand dust storms is a process that accelerates land desertification, and can also be considered as an indicator of land desertification at a certain stage Thus, it is of significance both in theory and practice to reveal the interaction between these two phenomena Based on the data from the Erdos Plateau and its surrounding areas, a study has been made of the effect of land desertification on sand dust storms A non linear relationship has been established between sand dust storm frequency and the index of land desertification (I ld ), which is defined as the percentage of the area of desertified land of the total This relationship indicates a threshold at I ld = 30% When I ld < 30%, the sand dust storm frequency did not change with an increasing I ld ; however, when I ld > 30%, the sand dust storm frequency increased rapidly This threshold means that the sand dust storm frequency would increase abruptly when the man induced I ld exceeds 30% This study also deals with sand dust storm frequency in response to the change in the area of cultivated land The time series of annual number of sand dust storm days in the neighboring area has been related with the time series in the annual number of strong wind days and the time series in the area of cultivated land. As a result, a multi regression equation has been established, based on which the relative contributions of the changes in land use and in number of strong wind have been estimated as 59 7% and 40 3%, respectively This result indicates that the frequency of sand dust storm may be effectively decreased by reducing the area of cultivated land and restoring steppe ecosystem in the ecologically fragile areas in arid and semi arid climates