Optical Remote Sensing Saturation Characteristics of Biomass of Pinus yunnanensis Forests in Different Ecological Regions of Yunnan Province

The study calculated the aboveground biomass density of Pinus yunnanensis forests using forest resource secondary survey data based on Landsat 8 OLI remote sensing images. Using the semi variogram in geostatistics, the spectral saturation characteristics of the original band of biomass were analyzed. The results showed that except for the CY ecological regions, the biomass of P. yunnanensis forests in all ecological regions had the strongest negative correlation with the original band of b6 of OLI. The reflectance of the b6 band in each ecological regions decreases with the increase of biomass and eventually tends to saturation, showing a certain regularity. The biomass saturation values of each ecological regions are 205.863 t/hm² for NW, 118.675 t/hm² for NE, 223.375 t/hm² for CY, 190.385 t/hm² for SC, 210.750 t/hm² for SW, and 167.354 t/hm² for SY. The higher saturation values occur in the central and western regions of Yunnan, while the lower saturation points are distributed in the northeast and southern regions of Yunnan, which is strongly correlated with the suitable growth areas of P. yunnanensis forests. This provides a reference for the saturation phenomenon in estimating biomass using optical remote sensing data sources and technical support for precise inversion of biomass.