Forest Vegetation Change And Its Response To Climate Change In Wuyi Mountains Area

According to the fifth report of the IPCC,the surface of the past three decades has been warmer than any decade since the 1950 s.The atmosphere and ocean have begun to warm up.The snow cover and snowfall have gradually begun to decrease.The sea level has risen by an average of 0.19(0.17 to 0.21)meters.The seawater has eroded the coastal zone,and the storm surge has intensified.The concentrations of greenhouse gases such as carbon dioxide and methane have increased.The speed of increase begins to accelerate rapidly and so on.Since the 1950 s,many of the climate changes observed by humans around the world have never been seen before in the past hundreds or even thousands of years.The impact of climate change on forest ecosystems and feedback mechanisms have gradually become human.Important development issues of concern,vegetation development and growth are sensitive to changes in the climate environment.The study of forest vegetation evolution in high latitudes of northern China was affected by climatic factors.The study used MODIS-NDVI data and TM/ETM+ data,combined with 62 years of meteorological observation data,using VFC dichotomous model,Mann-Kendall nonparametric test,and distance.Flat trend analysis,sliding T test and spatial correlation analysis method,to explore the evolution of climate change and its mutations to vegetation cover in Wuyiling area from 1975 to 2016,and to correlate the spatial variation of different climate factors with vegetation cover types.analysis.This paper has obtained the following conclusions through research:(1)In the Wuyiling area,the temperature has shown a significant upward trend in the past 62 years(0.557°C /10 a,P<0.0001);the overall precipitation shows a trend of constant fluctuations,and the inter-annual rainfall is weak(-14.052mm/10a),P <0.0001).The annual average maximum and minimum temperature showed an upward trend.The winter(0.692°C /10a)and the annual average minimum temperature(0.7229°C /10a)had the fastest temperature increase,and the autumn(0.264°C/10a)was the slowest.The seasonal variation of precipitation is obvious,and the fall is the fastest in autumn(-12.168mm/10a),while the summer is slightly increased relative to the annual rainfall(0.446 mm/10a).In general,the climate change in the Wuyiling protected area shows a trend of warm and dry development.Through the analysis of themutation test,the active period of the climate factor in the study area was 1980-1995.(2)There are significant regional differences in different vegetation cover types in the study area.The annual average vegetation coverage index is 0.673,and the vegetation cover area(NDVI?0.1)accounts for 87.69% of the total area of ??the Wuyiling reserve.Vegetation coverage area(NDVI ? 0.8)accounted for the largest proportion.Due to the warming and drying trend of the climate and the characteristics of the terrain being high in the north and low in the north,the different types of vegetation cover have significant spatial differences.From the spatial distribution of vegetation coverage and vegetation cover change trend,the mountain cover with high vegetation cover index is mixed forest and coniferous forest,which is strongly influenced by interannual climatic factors,and the spatial distribution of grassland is subject to seasonal hydrothermal conditions.Greater impact.Vegetation coverage in areas close to cultivated land and residential areas is greatly affected by human activities.The vegetation cover change in the swamp wet area widely distributed in the Wuyiling area is relatively stable.(3)The coverage of various vegetation types in the Wuyiling area is changed by long-term hydrothermal conditions.Before the climate change,the temperature and precipitation are decreasing(-0.0087°C/10 a,-10.206mm/10a),Wuyiling overall The coverage is good(mainly medium and high-grade vegetation coverage with NDVI greater than 0.6),the high-grade vegetation coverage area rises from the center to the northeast,and the low vegetation coverage area accounts for a small proportion of the total area.After the sudden change of climate,the overall temperature of the study area increased sharply,and the trend of warming and drying of precipitation decreased significantly(0.6209°C/10 a,-12.768mm/10a).The medium-high-grade vegetation coverage area was lower from the mountainous area with high altitude to the surrounding area.Regional divergence declines,and high vegetation coverage only maintains high vegetation cover in wet areas.During the abrupt change of climate warming and dehumidification,the vegetation coverage decreased significantly,and the area change before and after the mutation of all grades of vegetation coverage area:high > medium low > medium > medium high > low,high vegetation cover gradually degraded to medium and The middle and low vegetation cover areas are divergent and descend from the central high-altitude mountainous areas to the surrounding low-lyingareas.The decline of different vegetation cover types affected by climate change: mixed forest > grassland > coniferous forest > cultivated land > wetland.The rate of vegetation cover degradation during the climate abrupt change period in 1980-1995 was much higher than that during the 1975-2016 climate change period.The spatial change of land cover was the most significant and the degradation was the most serious.(4)The correlation analysis between NDVI and climatic factors in the growing season of the study area has obvious spatial differentiation law.The spatial correlation coefficients of temperature and precipitation are 0.161 and 0.068,respectively,and the positive correlation pixels account for 56.67% and 42.79% of the total pixel area,respectively.The correlation between the temperature factor and the area is higher than the correlation with the precipitation factor;that is,the spatial correlation of the temperature factor is higher than the precipitation factor,and the temperature is the dominant factor affecting the change of vegetation cover,which is also the cause of Wuyiling.The main influencing factors of regional vegetation degradation.(5)Sparse island-like permafrost and seasonal frozen soil are widely distributed in Wuyiling and surrounding areas.With the warming of the climate,the permafrost regions in the permafrost regions of northeastern China are frequently degraded,and the temperature changes drastically.The reaction is more sensitive;especially in recent years,due to the warming and drying trend of the climate,a series of changes in the environment caused by the degradation of frozen soil in the study area may lead to the growth of vegetation in the short term;On the above,the damage to the local natural environment will far exceed the positive conditions for the growth and development of the vegetation.The results of this environmental change will also have a series of far-reaching effects on the growth and development of forest vegetation in different periods in the Wuyi Mountains area.