Spatial and temporal changes of vegetation net primary productivity and its relation with climatic factors in Guangxi, China

Abstract

ABSTRACT MOD17A3 NPP datasets from 2000 -2010 and meteorological data were used to quantitatively analyze the s patial and temporal variations of vegetation NPP and its correlation with meteorological factors b y using linear regression and correlation analysis methods in Guangxi. R esults show : (1) the annual NPP ranged from 626 to 715 g &‡P -2 ‡D -1 , with an average of 663 g &‡P -2 ‡D -1 . The average annual vegetation NPP was higher in the west and east while lower in the middle and north part of the study area. T he highest NPP (U 900 g &‡P -2 ‡D -1 ) mainly distributed in Baise, C hongzuo, Fangchen ggang and Wuz hou. While the lowest NPP (O 450 g &‡P -2 ‡D -1 ) mainly located in cities of Guigang and Hezhou. (2) In recent 11 years, the linear changing trend of NPP in Guangxi was decreased slowly . The regio ns of NPP with no significant difference (P>0.05) , increased significantly (P<0.05) and decreased significantly (P<0.05) were respectively about 93.15 %, 0.80 % and 6.05 % of the total study area. The area with an annual NPP decreased rate lower than -10% occ upied 26.96% of the total study area, and the area with more than 10% NPP increment was 8.37%, and an unchanged area (NPP variation from -10% to 10%) accounted for 64.68%. (3) At the annual time scale, the correlations between vegetation NPP and temperature/precipitation were spatially various in G uangxi . The correlation of vegetation NPP with temperature was positive in 58.41% of the total area, and negative in the rest 41.59%, while its correlation with precipitation was posi tive in 38.16% of the study area, and negative for the other 61.84%. The above analysis indicated that temperature affecting vegetation growth mo re remarkable than precipitation. Keywords: N et primary productivity; MOD17A3; Guangxi