湿润及半湿润地带的土地风沙化问题

半湿润及湿润地带只要具备沙物质组成的地表,植被遭到破坏,沙体裸露和干季与风季在时间上同步性的条件下,经风力作用的结果同样可以产生风沙活动,并塑造了沙丘起伏的地表景观,从而造成生物生产量下降土地生产潜力的衰退,地表出现类似沙漠化环境的土地风沙化。但和干旱及半干旱地带的沙漠化土地相比除了具有类似的风沙地貌特点外,还有着其他显著的差异:1.因处于半湿润及湿润的气候条件下,在-般的情况下,风沙地表景观往往在干季风季表现得非常明显,而在多雨炎热少风的季节,风沙地表景观便不十分显著,在景观上具有季节变异性的特征。2.从宏观的地理分布来说,面积较半干旱及干旱地带沙漠化土地的范围为小,且分布零散,但因处于人烟稠密经济发达的地区,风沙的危害直接影响人们生活环境。3.从环境退化的过程来看,还未使整个周围环境全部退化,只不过在整个绿色的原野中有斑点状风沙地貌景观的点缀,并仍有-定的生产力。4.地表虽有风化活动所形成的地貌形态,但从发育规模及形态特征来看,其形态结构都较简单。5.由于上述诸特点,从国土整治的需要来考虑,对于半湿润及温润地带的沙地,不仅只限于防止其蔓延,而更重要的是如何在已恢复生产力的土地上再进行高效益的开发利用,这与干旱半干旱地带沙漠化土地整治中,

Phenomena of Blownsands and Their Impacts on Lands in Humid and Subhumid Zones

In subhumid and Humid zones even in some Parts of tropical and sub-tropical regions blownsand activities and iandscape of undulating dunes could be caused on surface under wind force as long as the surface is composed of sand materials and timely drought season synchronize wind season,and in the cases of vegetation was destructed and Sandy body was exposed without green coverage. Comparising with the land desertification in arid and semiarid zones, the blownsand impacted environment has remarkable differences as the following although it is characterized by the similar aeolian landfo-rm. 1.Because of the sub-humid and humid climatic condition, in most cases, surface landscape of blownsand is obviously manifested in drought se ason and-wind season. But in rainy and hot season wrth less winds, the landscape is characterized by seasonal varialility. 2.From viewpoint of the macroscopical geographic distribution, the blown-sand landscape covers a small area then the area of land desertification in a rid and semi-arid zones, and distributed scattered. But the phonomena of blownsand took place mostly in the densely populated and developed economic regions, so peoplels living environment is directly impacted under hazard of dlownsands, 3. According to the process of environment degraadtion, the phenomena of blownsand occupy a small percentage of green fields and characterized by it sparsely distribution of landscape of blownsnand landform. But these blow nsand impacted areas are productive. 4. There are geomorphological features on surface under blownsand activ yities, but from the viewpoint of developmental scale and morphological features,the surface feature and structure are monogenetic. 5.In arid and semi-arid zones, the renovation of land desertification is aimed to control the enlargement of land desertification as the main step and the appropriate utilization is considered as second step. In consideration of national territory renovation, the blownsand impacted lands in humid and sub-humid zones are not only aimed to control its expasion, but also is mainly aimed to redevelop and reuse the renewed productive lands for harvesting high economic benefits. Some refrerential figures and photos of the example of blownsands in humid and sub-humid zones are attached in the paper.