Dynamic Change Of Vegetation Coverage And Response To Climate Change Between The South Of Qinling And North Of Daba Mountains

In this paper, using data of2001-2012MODIS (IGBP) land cover types, NDVI data fromApril2000to October2012and the meteorological data of38national baselinemeteorological stations from January1960to December2012, and method of the applicationa linear regression, Mann-Kendall trend analysis, potential evapotranspiration, trend lineanalysis, NDVI maximum value analysis and methods of vegetation and climatic factorscorrelation analysis, to analysis vegetation of the variation of the south Qinling Mountains tothe north Daba Mountain region and variation of temperatures, precipitation andevapotranspiration characteristics nearly53years in the study area, as well as in response tochanges in the relationship between vegetation cover in the region, and each of themeteorological factors, as well as combine the overall analysis and zoning controls fordetailed analysis, research made The main conclusions are as follows:(1) The descending order of land cover types on average accounted for nearly12years inQinba regional is: forest, agricultural land, grassland, shrubland, urban land and water bodies,and forest area significantly increased, but grassland, shrubland and agricultural landdecreased slightly; while the total area of forest, agricultural land, grassland, shrublandunchanged, indicating that small changes in NDVI affect by the land cover types change.(2) In spatio, the situation of vegetation covering in Han River valley, east of the Qinbaareas was better, followed by the hilly areas of eastern edge, while Western Qinling mountainvegetation covering was worse than other areas. In temporal, in growing season, the change ofaverage NDVI amplitude is slightly in nearly12years in study region, but it was significantdifferences in different season, increased first and decreased flollowed in Spring, decreasedfirst and then increased in Summer and Autumn. In regionally, in Spring, the vegetation coverdecreased in western of Qinba areas; in Summer, the western region has a obviously increasedtrend by nearly13years, followed by parts of eastern, mainly to increase in Autumn, and partof the east and west regions has a significant increasing trend; in entire Growing Season, it isremain basically unchanged in most areas, a slight increase in the western region. Indicatedthat the vegetation covering changed significantly in seasonally in West Qinling region, andreduced in spring, increased in summer and autumn.(3) The changes of temperature in Qinba region, as a whole, it appears a warm spring; inSummer, temperature rised in the Midwest, there is a downward trend in the eastern part, and the overall performance of the temperature was droped; temperatures increased significantlyin Autumn, which appears a warming Autumn; in Growing Season, temperatures showed anupward trend, the rising trend was the most significant in the Midwest. The precipitationchanges in Qinba areas, in Spring, it was a more significantly downward trend of rainfall ineastern, while the slightly rised trend in the western region; in Summer, the precipitation has aincrease trend in the eastern region, while the western region was significantly reduced; inAutumn, the change of precipitation was not significantly, which appeared slightly dryingtrend; in the Growing Season, the precipitation declined slightly during whole region. Thechange of evapotranspiration in Qinba area, in Spring, from the past53years,evapotranspiration significantly increased in the study area; in Summer, there was asignificant downward trend in overall, a significant downward trend in the east part, and thewest part rose slightly; in Autumn, evapotranspiration declined slightly; in the entire GrowingSeason, evapotranspiration showed a significant decline, most evident in the eastern region. Inwinter, evapotranspiration mainly falled in the eastern region is more obvious, and winterevapotranspiration increased slightly in western region; and annual evapotranspirationshowed a significant decline, most evident in the eastern region.(4) The correlation characteristics of vegetation cover with climatic factors in Qinbaareas, the overall analysis concluded that vegetation conditions in a wide range of eastern partof study area affected by temperatures restrictive effects more significant, especially in middleQinba the central region, while Mindie mountain areas in the western region of the chiptemperature rise would have a certain vegetation growth promoting effect may be due to thehigher elevations of the region, making the temperatures become a major factor in the growthof vegetation; NDVI and precipitation mainly related to the positive, especially in the east ofcentral mountainous area and Longnan region, belong to the western of study area, showed asignificant positive correlation, indicating that precipitation in most parts of the study area topromote the role of vegetation growth conditions, but in the central west region of the studyarea showed a negative correlation phenomenon, indicating that the regional precipitation isnot the main factor affecting the growth of vegetation; vegetation growth status in Longnanmountainous and Eastern region mostly affected by the inhibition of evapotranspirationobviously, but in the middle west part and western Mindie mountains affected byevapotranspiration the influence was weak, and there waas no obvious correlation between vegetation and other areas of evapotranspiration.(5) The hysteresis effects of Qinba regional vegetation cover and various climatic factors,in regionally, the eastern region: Spring temperatures promote the role of the regionalvegetation obviously, influence of precipitation on vegetation was not significant, andevapotranspiration status significantly lag on vegetation growth; summer temperatures andevapotranspiration of the regional vegetation significantly inhibited, while precipitation andvegetation showed a significant positive correlation, and exhibit hysteresis; autumn vegetationthat significantly affected by temperature, effects on vegetation and precipitation possessedsignificant lag, and evapotranspiration affected by weak; winter vegetation growth conditionsin the area affected by climate change factors is weak, and the role of vegetation on wintertemperatures significantly in precipitation and evapotranspiration. Central Region: springvegetation growth conditions significantly affected by evapotranspiration; vegetation growthstatus of the region affected by the summer and autumn climatic factors is weak, the regionmay be due to the valleys and basins dominated terrain, abundant groundwater, weakening theclimate on vegetation degree of influence; winter climate change factors influence vegetationgrowth is weak, but the temperature effect significantly in other climatic factors. Westernregion: spring vegetation growth status by promoting pre-season temperature andprecipitation significantly, while the same evapotranspiration weak correlation; summervegetation growth status by various climatic factors significantly affected, and theprecipitation and evapotranspiration impact on vegetation with a lag; vegetation growth statusautumn climate factors are affected significantly and are subject to temperature andprecipitation affect the performance of a certain lag; winter vegetation in the area is alsoaffected by changes in various climatic factors influence is weak. Overall condition of thevegetation cover in the study area relative to the volume of precipitation andevapotranspiration lag of1to2months, while the role of vegetation in response to theresponse of evapotranspiration to precipitation is more obviously. Above conclusion showsthat vegetation growth status between different regions of Qin Bashan differences betweenareas in response to climate significantly, probably mainly due to the climate of the region islocated in the transition zone, terrain and other reasons.