Evolution of vegetation coverage and its response to abrupt climate change in the Wuyi Mountains National Nature Reserve

To explore the influence of climatice factor changes and even mutations on vegetation evolution in high-latitude forest cover areas in northern China,we used MODIS-NDVI data and TM/ETM+ data, combined with a 62-year meteorological observation dataset, We analyzed these data using a pixel dichotomous model, cumulative anomaly analysis, a Mann-Kendall non-parametric test, sliding t-test, and correlation analysis. We discussed the evolution of climate change and its mutations on vegetation cover in the Wuyi Mountains National Nature Reserve from 1975 to 2016, as well as different climatic factors and vegetation cover types. The spatial variation was correlated. The results showed that:(1) Climate change in the Wuyi Mountains protected area exhibited a trend of warm and dry development. The annual average temperature increased(0.557℃/10 a), the annual average minimum temperature and winter temperature increased fastest, whereas the autumn increase was the slowest. The annual variation in precipitation was small(-14.052 mm/10 a); however, the seasonal variation was obvious. Through the mutation test, 1980-1995 was a period of sudden change in climate warming and dehumidification.(2) The NDVI of the vegetation growing season in the study area was 0.673, and the area covered by vegetation accounted for 87.69%, of which the highest vegetation coverage area accounted for the largest proportion.(3) During the abrupt climate change period, NDVI decreased significantly during the growing season, and vegetation degradation was severe. There was no significant change in the low vegetation coverage area, and the high vegetation coverage area began to gradually degenerate into medium and low-level vegetation coverage areas. The degradation of vegetation cover in space was mainly reduced in the central mountainous areas along the low hills and surrounding areas. The extent of decline in different vegetation coverage areas was as follows: mixed forest > grassland > coniferous forest > cultivated land > wetland.(4) The correlation coefficient between annual average maximum NDVI and annual average temperature and annual average precipitation in the Wuyi Mountains protected area was 0.261 and 0.068, respectively, and the positive correlation area accounted for 56.67% and 42.79% of the total area, respectively. Significant spatial differences were observed. The temperature factor affecteds the spatial extent and capacity of vegetation coverage, and had a higher spatial correlat