| The IPCC 5th assessment report on climate change in 2013: from 1880 to 2012, the earth's surface temperature increased 0.85?, by the the end of 21 st century, the global mean surface temperature will increase 0.3~4.8?. Warming phenomenon has been confirmed by observational evidence. Global climate change has caused a significant impact on terrestrial ecosystems, while vegetation as the main body of terrestrial ecosystem will make sensitive response to global climate change. The mountain which as the most active interface and the most vulnerable geographic unit of terrestrial ecosystems is a driver and amplifier to the environment changes, so the mountain vegetation ecosystem is more sensitive to global change. Mountain ecosystem also takes on the supply of production and living materials as well as protection of natural ecological service. So the changes of mountain ecosystem are causing great concern of academia and society. Thus, as the high resolution remote sensing data sources are becoming more and more rich, using these datas to carry out a research on vegetation cover change and its response to climatic factors attracts widespread attentions of scholars at home and abroad.West Henan Mountain is the extension of Qinling Mountain in Henan province, located in the transition zone of the subtropical to warm temperate zone and humid to semi-humid zone. It is a fragile and sensitive area of global change. Under the background of global warming, the further study on spatial and temporal variation of precipitation and temperature in West Henan Mountain and the response of vegetation cover to precipitation and temperature variation, on the one hand it can provide material support for the analysis of changes in the climate zone in China, on the other hand it can also provide a scientific basis for the area to make local ecological environment monitoring programs. Based on MODIS-NDVI(2000-2013), DEM, temperature(1984-2013) and precipitation(1998-2013) data, with the aid of the MRT, ArcGIS, ANUSPLIN, Kriging and SPSS software, using the method of trend analysis, correlation analysis and so on, this paper studied the spatial and temporal variation of temperature, precipitation and vegetation cover as well as the response of vegetation cover to variation of temperature and precipitation in West Henan Mountain. And taking 500 m as the gradient, this paper mainly discussed the response of vegetation cover to variation of temperature and precipitation across altitudinal gradients, in further to clarify the response of vegetation variation to climate change of different landform units in the study area, in order to provide decision-making basis for the restoration and protection of vegetation in different ecological units under the background of global warming. Relevant conclusions of this study are as follows:(1) During 2000—2013, the vegetation NDVI of West Henan Mountain shows a trend of significant growth, the growth rate is 0.022/10a(p>0.05). And the growth rate in autumn is significantly higher than any other season, it suggests that in the context of global warming the vegetation coverage condition of the study area shows the extension of growing season is stronger than growth season in advance.(2) From <500m to >2000m, the average NDVI value increases firstly and then decreases, while the NDVI change trend decreases gradually.(3) During 1984—2013, the spatial distribution of annual average temperature in West Henan Mountain shows a phenomenon that the value in south is higher than that in north and the value in east is higher than that in west. In the 30 years, the annual average temperature shows a significantly growing trend at the rate of 0.3?/10a(p<0.05). During 1998—2013, the annual average precipitation decreases gradually from southeast to northwest. In the 16 years, the precipitation shows a decreasing trend at the rate of 54mm/10a(p>0.05).(4) As the altitude increases, the annual average temperature of the study area decreases linearly, the temperature vertical decreasing rate is 0.4 ?/100 m. But as the altitude increases, annual precipitation of the study area decreases firstly, then increases, and at last decreases again, the maximum value appears in 1500~2000m area.(5) The spatial distribution of correlation coefficients between NDVI and temperature shows that positive correlation regions(34.9%) are mainly in the south of the study area, and negative correlation regions(65.1%) are mainly in the north of the study area. The correlation coefficients between NDVI and precipitation increase gradually from southeast to northwest, the positive correlation regions(32.3%) are mainly in the northwest of the study area, and the negative correlation regions(67.7%) are mainly in the southeast of the study area.(6) In the 14 years, the annual average temperature has a weak negative correlation with NDVI, the coefficient is-0.177. The annual average precipitation has a weak positive correlation with NDVI, the coefficient is 0.163. The temperature has a lag effect on vegetation, but the lag effect between precipitation and NDVI is not obvious.(7) The vegetation in West Henan Mountain under the influence of precipitation is greater than that affected by temperature, the higher the altitude, the more obvious the influence. |
PDF Full Text Request