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Vegetation Index Change And Its Driving Force Analysis In Daba Mountains

Posted on:2013-05-06Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y RenFull Text:PDF
GTID:2230330374472221Subject:Physical geography
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This paper studied vegetation cover variations and its driving force analysis in Daba Mountains from1998to2009based on SPOT-NDVI data, climate factors and TM data. In terms of the analysis methods of MVC, regression, partial correlation and wavelet etc, to analysis vegetation index change and its influencing factors in Daba Mountains, at which aims revealing subtropical forest vegetation index change and its driving force factors. The result as follow:(1) The vegetation change from1998to2009in Dapa MountainsThe coverage of vegetation is high in Daba Mountains, the trend of the NDVI in different time scales is that:The vegetation cover has a significant increasable trends as a whole in Dapa Mountains during1998to2009, and different vegetation types of NDVI variation in the spring and autumn has the greatest contribution to annual NDVI changes; the NDVI values of different vegetation types is broad-leaved forest> coniferous forest (winter for coniferous forest> broad-leaved forest)> irrigation grass planting vegetation; the NDVI is lowest in February, largest in July, vegetation growth is obvious in spring.In dabashan mountain vegetation cover main show the increasing trend, accounted for the areas of NDVI decrease only0.38%, mainly for the distribution of vegetation near the town; A slight increase in the trend NDVI area is larger, the total area respectively type percentage for:planting vegetation is39%, irrigation grass forest is62.36%, broad-leaved forest is85%, coniferous forest is78%; NDVI value has a significant increase trend is irrigation grass in the area of hanjiang river, coniferous in PingLi, broad-leaved forest in fangxian, and plant in the north of zhushan, planting vegetation NDVI increased area as high as59.2%.(2) The driving forces of vegetation variation analysisThe temperature and rainfall in30a time scale are rising. In Daba Mountains, and in12a time scale, the temperature has a slight down trend, rainfall with growth trend. By wavelet analysis shows that the temperature and rainfall change trend are low-high-low-high-low in30a time scale, mutation point all appear in1983,1991,1998and2007. In the12a time scale, the temperature change regularity of the cycle is not obvious.The NDVI value showed significant correlation with temperature of current month, the previous month and two months before the current month, but precipitation is weak positive correlation with NDVI, vegetation growth mainly affected by temperature change. In the space, the pixels of auanal NDVI value which are negatively correlated with the temperature account for65.3%of the total, which showed that the rise of temperature could lead to the increase of evaporation, thus restrain the growth of plants.Space region of human disturbance vary widely in the Dapa Mountain, Daba Mountain vegetation less interference by human activity in the northwest of Hubei Province. The area of the medium of human disturbance is most. Four towns, which suffer intensity of human disturbance is different from the others. (3) Case analysis-the town of shennongjiaMore than70%of the total area is cover by broad-leaved forest in Shennongjia Forest, residents, budding and planting vegetation has the percentage of3.20years later, residential and budding area has substantially increase, and planting vegetation in the area first increases and then decreases, shrub area to maintain steady growth, broad-leaved forest’s change area is small, coniferous forest decreases rapidly, we know that human activities on the regional impact is strengthening.The temperature correlation with the NDVI of same month, the sensitivity of the rainfall is higher in last month. In the space, the area of temperature and NDVI is negatively correlation is large. The area of rainfall was positively associated with NDVI mainly distributed in the southwest, the low altitude area of irrigation grass and cultivated vegetation growth has certain stimulative effect, the vegetation growth has slight inhibition in high altitude area of shennongjia.The human interference intensity differences in shennongjia,87%of the region interference index is less than0.3, part of the human activities weak interference area. Individual towns, on which human influence is stronger, including for red ping town, the pine town, xinhua town and so on. The county lush vegetation, land area is big, human activities in a small range, population distribution relative concentration, mainly for the town and surrounding areas, which can lead to human activities on the local interference are very prominent, and other outside of town of large area area affects obviously smaller.
Keywords/Search Tags:vegetation cover, climate response, human impact, Dapa Mountains
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