干旱区科学
榦旱區科學
간한구과학
JOURNAL OF ARID LAND
2014年
1期
80-96
,共17页
k-nearest neighbor%Mahalanobis%most similar neighbor%MODIS BRDF-adjusted reflectance%forest inventory%the policy of Reducing Emission from Deforestation and Forest Degradation
As climate change negotiations progress, monitoring biomass and carbon stocks is becoming an im-portant part of the current forest research. Therefore, national governments are interested in developing for-est-monitoring strategies using geospatial technology. Among statistical methods for mapping biomass, there is a nonparametric approach called k-nearest neighbor (kNN). We compared four variations of distance metrics of the kNN for the spatially-explicit estimation of aboveground biomass in a portion of the Mexican north border of the intertropical zone. Satellite derived, climatic, and topographic predictor variables were combined with the Mexican National Forest Inventory (NFI) data to accomplish the purpose. Performance of distance metrics applied into the kNN algorithm was evaluated using a cross validation leave-one-out technique. The results indicate that the Most Similar Neighbor (MSN) approach maximizes the correlation between predictor and response variables (r=0.9). Our results are in agreement with those reported in the literature. These findings confirm the predictive potential of the MSN approach for mapping forest variables at pixel level under the policy of Reducing Emission from Deforestation and Forest Degradation (REDD+).