沼泽疏干

The region in the altitude f rom 4400 to 4600 meters , which is mainly covered by alpine meadow and alpine swamp meadow , is st rongly degraded by the stock raising with it s influence radius of about 24 kilometers. The influence distance perpendicular to roads is also 24 kilometers , since road const ruction accelerates human2induced destruction to vegetation. Vegetation in shade aspect is rising due to the increase in precipitation , while vegetation in sunny aspect tends to be stable or degraded because of the enhancement in sunlight . Furthermore , the vegetation coverage is influenced by the groundwater level . In near riverbed fields , where the depth of groundwater is shallow , plant s can easily grow ; while in far riverbed fields , vegetation is prone to degrade due to drainage. The radius of river influence is 24 kilometers.

海拔4400～4600m的较低海拔地带退化最强烈，主要为高寒草甸与高寒沼泽草甸受牧业影响较大；牧业影响半径为24km；道路的影响范围为24km，道路的修建加速了人类对高原植被的破坏作用；阳坡植被呈现趋于稳定和退化的趋势，阴坡植被表现为增长的趋势，降水量增加是源区植被，尤其是阴坡植被变好的重要原因，而太阳光照增强是导致阳坡干旱和植被趋于退化的潜在原因；近河床区地下水位埋深较浅，植被生长具有稳定的地下水源；在远离河床的一定区域内，地下水易于疏干，植被易于退化，河流影响范围为24km。

The natural causes were landform, parent materials and weather. The man-made causes were over grazing and estrepement. The natural factors were the basic causes of sandification in Hongyuan.

自然成因包括地形地貌和水文母质因素、气候因素；人为成因包括过渡放牧，滥垦乱抢和疏干沼泽等因素。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。