Forest ecosystem health assessment and analysis in China

Based on more than 300 forest sample plots surveying data and forestry statistical data, remote sensing information from the NOAA AVHRR database and the daily meteorological data of 300 stations, we selected vigor, organization and resilience as the indicators to assess large-scale forest ecosystem health in China and analyzed the spatial pattern of forest ecosystem health and influencing factors. The results of assessment indicated that the spatial pattern of forest ecosystem health showed a decreasing trend along latitude gradients and longitude gradients. The healthy forests are mainly distributed in natural forests, tropical rainforests and seasonal rainforests; secondarily orderly in northeast national forest zone, subtropical forest zonation and southwest forest zonation; while the unhealthy forests were mainly located in warm temperate zone and Xinjiang-Mongolia forest zone. The coefficient of correction between Forest Ecosystem Health Index (FEHI) and annual average precipitation was 0.58 (p<0.01), while the coefficient of correlation between FEHI and annual mean temperatures was 0.49 (p<0.01), which identified that the precipitation and temperatures affect the pattern of FEHI, and the precipitation's effect was stronger than the temperature's. We also measured the correlation coefficient between FEHI and NPP, biodiversity and resistance, which were 0.64, 0.76 and 0.81 (p<0.01) respectively. The order of effect on forest ecosystem health was vigor, organization and resistance.