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The normalized difference vegetation index(NDVI)is used extensively to describe vegetation cover and ecological environment change.The purpose of this study was to contrast the response of different tree species growing in the same habitat to climate change and retrieve past NDVI using tree-ring width data from tree cores collected from the transitional zone of Pinus tabulaeformis and Picea crassifolia in the Luoshan Mountains in the middle arid region of Ningxia.Correlation analysis indicated that radial growth of P.tabulaeformis is more sensitive to precipitation and temperature change than that of P.crassifolia.Natural factors such as water availability and heat at this elevation are more suited to the growth of P.crassifolia,and are more advantageous to its renewal and succession.P.crassifolia is probably the better of the two species for protecting the forest ecosystem and conserving water in the Luoshan desertification area.Ring width of P.crassifolia correlates significantly with average NDVI for April–May(r=0.641,p<0.01),and both of them are influenced positively by precipitation in April–May.The reconstructed NDVI for 1923–2007 shows the relatively low vegetation cover occurred in the 1920s–1930s,the1960s–1970s,and the early 21st century.The reconstructed NDVI better reflected the drought climate in the study area.
The normalized difference vegetation index (NDVI) is used extensively to describe vegetation cover and ecological environment change the purpose of this study was to contrast the response of different tree species growing in the same habitat to climate change and retrieve past NDVI using tree-ring width data from tree cores collected from the transitional zone of Pinus tabulaeformis and Picea crassifolia in the Luoshan Mountains in the middle arid region of Ningxia. Correlation analysis indicated that radial growth of P.tabulaeformis is more sensitive to precipitation and temperature change than that of P .crassifolia.Natural factors such as water availability and heat at this elevation are more suited to the growth of P.crassifolia, and are more advantageous to its renewal and succession. P..crassifolia is probably the better of the two species for protecting the forest ecosystem and conserving water in the Luoshan desertification area .Ring width of P..crassifolia correlates significantly wit h average NDVI for April-May (r = 0.641, p <0.01), and both of them are clearly positively by precipitation in April-May. The reconstructed NDVI for 1923-2007 shows the relatively low-level cover cover in the 1920s-1930s , the 1960s-1970s, and the early 21st century. reconstructed NDVI better reflected the drought climate in the study area.