Environment and Ecology
MAO Xue-gang, LI Ming-ze, FAN Wen-yi, JIANG Huan-huan
Based on remote sensing data from three periods of 1980s, 1990s, and the period after 2000 as well as the data of plots in forest resource inventory over the same periods, forest biomass of Xiao Hinggan region was estimated by using the remote sensing information model. With the combination of GIS and geo-statistics, this paper studies the temporal changes in forest biomass, spatial autocorrelation and heterogeneity of Xiao Hinggan region in the three periods of 1980s, 1990s, and the period after 2000. Results indicated that the overall biomass presented fluctuation change in the research area from the 1980s to the 2000s. With relatively low biological value, low-grade biomass was dominant in the 1980s, and there was contiguous distribution of low-value biomass, with high degree of spatial autocorrelation. However, the random factors of medium and higher biomass increased, indicating the man-made interference degree continuously strengthened. In the 1990s the main advantages biomass in the study area was medium biomass, which evolved from dominant low-grade biomass in the 1980s. The changes in the 10 years showed that overall biomass tended to recover. For the data were mainly concentrated in the late 1990s when the Natural Forest Protection Project (NFPP) had been launched that made the forest status towards a good direction, the overall biological value was increased. After 2000 the spatial autocorrelation of overall biomass in the research area was not high, but medium and higher biomass was similar and changed evenly in every direction. Median biomass was distributed widely, while high-value biomass was of small patches with fragmentation, and the spatial variability caused by random factors such as man-made disturbance or the factor of spatial autocorrelation was just similar, and appeared a stability trend.