【摘要】 农田防护林带对农田具有防护作用,可使平均风速降低51.6%,气温下降0.6℃,相对湿度提高5.9%,水面蒸发减少33.7%。随林地面积扩大和树体的增长,还可以减少夏季干热风发生频率和降低地下水位。林带防护范围内,土壤含水率较高,土壤盐分含量较低。距林带一倍树高范围内,农作物受胁地遮阴影响有所减产,但距林带树高20倍范围内,和对照点(林带25倍处)相比,小麦平均增产31%,千粒重增加6.9%;玉米平均增长22.9%,千粒重增加3.6%,含盐量平均降低0.03%左右。更多还原

【Abstract】 The shelterbelts play an important role in protecting the farmland,which may reduce wind speed by 51.6%,declining temperature 0.6℃,increasing relative humidity by 5.9%,and reduce water evaporation by 33.7%.As the enlangement of forestarea and the growth of trees,it also may decrease the frequency of sirocco in summer and reduce the water table.The water content is higher than and the salf content containing salt is lower in the soil of defending shelterbelts than thaf of contol plot soil.The yield reduction of the crop happens in the range of one horizontal distance of the trees height.But in the range of distance of 20 times of the height of trees(contrasting 25 times),the wheat yield increase production by 31%,and its weight of kilo grain increase by 6.9%.The corn increase production by 22.9%,and its weight of kilo grainincrease by 3.6%,salt content about decrease 0.03%.更多还原