Abstract:
To investigate the core areas of high productivity of Chinese fir and their influence factors, in this study, the improved CASA model was used to estimate the NPP of Chinese fir forests in Fujian Province in 2006, 2011 and 2016 based on remote sensing data, forest resource survey data and meteorological station data, analyze its spatio-temporal differentiation characteristics, and explore its relationship with various impact factors. The results showed that the annual average NPP values of Chinese fir forests in the study area in 2006, 2011 and 2016 were 804.03, 854.76 and 884.46 g/(m~2·a), showing the seasonal characteristics of high summer and low winter. The Chinese fir forests in the hierarchical statistical study area were dominated by medium and high productivity, with the core areas in Nanping and Sanming. The medium and high productivity Chinese fir stand units in three years accounted for 36.04%, 41.98% and 45.60% of the total area of fir forests in Fujian Province. The NPP of Chinese fir forest was significantly positively correlated with annual total precipitation, annual total solar radiation, altitude, slope, soil organic matter, total nitrogen and total potassium, and significantly negatively correlated with annual average temperature, aspect and total phosphorus. The NPP of Chinese fir forest generally increased with the increase of altitude, slope, annual total solar radiation, annual total precipitation and soil organic matter, and decreased with the increase of annual average temperature. The research showed that altitude, slope, annual total solar radiation, annual total precipitation, annual average temperature and soil organic matter were the important factors that affect the NPP of Chinese fir forests in Fujian Province.