Responses Of Vegetation Distribution To Soil Erosion Environment In Loess Hilly Region

In this paper, based on the analysis of soil erosion distribution and the research ofenvironmental characteristics, we evaluate objectively the respinse relationship between soilerosion and the pattern of distribution of vegetation under the influence of the reforestation.Based on the TM and Geoeye remote sensing image interpretation, we get the Yan Riverwatershed landuse and vegetation cover. Using the ArcGIS and ERDAS software to generatethree soil erosion maps based on ministry of water resources soil erosion grading standards.Considering Yan River Basin climate, topography, landuse and human impact factors, discussand analyse evolution and distribution of soil erosion and the relationship between soilerosion and environmental factors.The following conclusions:1) Yan River basin type of soil erosion mainly to moderate erosion, mild erosion andintensity of erosion followed, slightly eorded areas are mainly located in the valley areas. YanRiver basin between1990and2010, the trend of soil erosion is “weak-strong-weak”, the mostserious erosion occurred in2000. Yan River basin in1990-2000decade, soil erosionincreased from moderate erosion to intensity of erosion and pole strength erosion and severeerosion area surge; in2000–2010decade, soil erosion reinforced area is397.23km2and soilerosion lowering area is3933.59km2.2) In each year in different vegetation zones erosion distribution, small watershed inforest have strong ability to resist erosion, but between the forest zone and the forest–grassland zone, the small watersheds are on the same level. It’s proving that when thevegetation cover reaches a certain level or more, soil erosion will have a very significant rolein the containment. In the forest zone, the severity of soil erosion from strong to weakordering is Mao Baoze watershed> Dong Zigou watershed> Shang Henian watershed; Inforest and grassland zone, the severity of soil erosion ordering is WangJia watershed> XiaoHegou watershed> Chen Jiagua watershed; In grassland zone, the three watershed have thesame soil erosion level in1990–2010. In1990, soil erosion of Gao Jiagou is better than ShiZiwan and Zhou Jiashan. In2010, each watershed area of deep erosion decreasedsignificantly.3) The Yan River Basin is divided into7independent environment gradient zone in17mm unit. The first gradient to the third gradient in each period of soil erosion type mainly is moderate erosion, intense erosion followed; The seventh gradient in each period ia mainlymicro erosion, resist erosion ability than other several gradient; In each period, micro erosionarea with gradient increasing, when the average rainfall is more than522mm, the soil erosionminimum. From the area difference of view, small watershed area of effect on watershederosion state with gradient increase into undulating changes, its effects on the first gradientand the seventh gradient are not significant, effect of small watershed of sixth gradientmaximum.4) In grassland zone, there is a significant positive correlation between slope and soilerosion, elevation and soil erosion is negative correlation, elevation has significant correlationwith soil erosion in Zhou Jiashan watershed and Gao Jiagou watershed. In foreast–grasslandzone, the significant positive correlation between slope and soil erosion in3years, XiaoHegou watershed elevation has signifcant correlation with soil erosion; In forest vegetationzone, only the Dong Zigou watershed slope had significant negative correlation with soilerosion, it is proved that terrain factors have small influence on soil erosion in vegetationzone.5) Yanhe basin vegetation coverage in the45%division. Over a20–year period, from1990to2010, Yanhe basin vegetation experienced two stages that is destruction andrestoration, when the Yanhe basin vegetation coverage switch to under45%, soil erosion isagravation.6) The landuse characteristices of the nine investigation watersheds are match with theirown vegetation zone. In forest vegetation zone, there are significant correlations betweenlanduse and soil erosion intensity, mainly between cultivated and non-cultivated land, thecultivated land has the most serious soil erosion status in the three watershed of forestvegetation zone. The ordering of soil erosion from weak to strong in different landuse is:forest> grassland> other land> cultivated land. The decreasing of vegetation coverage isimportant driving force factor to aggravation of soil erosion, the aggravation of soil erosionaccompany the decrease of vegetation coverage, but the decrease of vegetation cover is notnecessarily accompanied with the aggravation of soil erosion.