Study on Pertinence between the Vegetation Indexes and the Aboveground Biomass of Sub-alpine Meadow of Zoige County

To discuss the pertinence between the vegetation indexes and the aboveground biomass of sub-alpine meadow of Zoige(Ruoergai) County and serve better for the ecological improvement,the statistical analysis was conducted between seven vegetation indexes(NDVI,RVI,DVI,SAVI,MSAVI,PVI and GVI) of Zoige area in July 2008 and the field survey data.Linear and non-linear(second-degree polynomial,cubic polynomial,logarithm and exponential) models were established respectively between the seven indexes and the aboveground biomass.The results showed that,for the six vegetation indexes(NDVI,DVI,SAVI,MSAVI,PVI and GVI) and the aboveground biomass models,the cubic polynomial model was the best,followed by the second-degree polynomial model,linear model and exponential model;and for the RVI-biomass model,the exponential model was the best,followed by the cubic polynomial model,second-degree polynomial model and linear model.Analysis showed that the polynomial model based on RVI-biomass was the best model,with the multiple correlation coefficient R2 being 0.8177;the precision test of the model indicated that the average error was 6.80%;the rating precision was 93.20%.The simulated biomass based on this model showed that the Zoige grassland biomass was higher in the southeast than in the northwest.