Shaanxi Province Vegetation Ecological Protection And Environmental Changes In Time Synchronization

Three important ecological protection function of vegetation are purifying atmosphere, conserving the water and soil, wind-break and sand-fixing. But exertion of these ecological protection functions are conditional. From the time series, only when vegetation's protection capability and environmental factor's change maintain very high time synchronism, the function can display well. Because the air pollution, the soil erosion, and the soil wind erosion have strong and weak annual changes, and the vegetation also has the rhythmic variation rule, if the relation of them is inverse, the exertion of vegetation's ecological function will be reduced. Based on investigation foundation, this paper takes Xi'an, Yan'an, and Yu Lin as the examples, and analyzes the synchronism relation between vegetation's ecological function and environmental problem.The primary contents are as follows:First, Annual change of the air pollutant density in Xi'an, which is higher in winner and lower in summer, presents "U" characteristic. But the purification ability of mainly realizes through dense leaf, which is determined by the leaf surface index. The leaf surface index may be influenced by climatic conditions, and it presents "parabola" figure during one year. The change relation of air pollutant density and leaf surface index are exactly opposite, which conduce to seriously restricting the vegetation's purification atmosphere function. Thus, conclusions of the conventional routes for estimating vegetation purification ability are often inaccurately.Second, the soil erosion problem is badly in Yan'an, and the annual change of rainfall erosion power, which is the strongest from June to August, assumes "unimodal" figure. The seasonal change of vegetation cover, which is the biggest from July to September, also presents "unimodal" figure. The time synchronized relations of them are uniform, which causes the sufficient exertion of the maintaining water and soil ecological function, and the protection effect is obvious.Third, the sandstorm activity is intense in Yu Lin. Within one year, distribution of the wind erosion climatic factors (C_we) assumes "unimodal" figure, whose character is increasing anxiously and then reducing slowly. Its peak value appears from March to May. But the seasonal change of vegetation cover presents slowly increasing and then reducing anxiously, and the peak value appears from August to September. The time relation of them are "dislocation", and the synchronized relation is bad. Based on Synthesizing character and rule of the dynamic change of environmental problems and vegetation cover in spatio-temporal variation in three areas, conclusions have been found: 1) There are many differences among most serious month when the main environment problem occurred. And the worst days of air pollution is in December January and February in Xi'an, soil and water loss is worst in July and August in Yan'an, while wind erosion is strongest in April and May in Yu'lin; 2) the length of the flourish period that annual rhythms of vegetation change in the three areas is different, the longest of which is in Xi'an, the second is in Yan'an and the shortest is Yu'lin. The flourish period indicates the North-south differences of the characteristics of the geographical distribution, that is, with the relocation of its geographical location, the length of the flourish period show a shortening trend.Based on these, the three synchronism coordinate models of correlation analysis, grey correlation and phase comparison were constructed, which supply reasonable method for synchronism measurement and make quantitative comparison analysis using these three models on vegetation protection of the eco-time synchronization. The results show that the eco-time synchronization relationship of the three ecological protection function of vegetation are different, and the best is the conserving the water and soil function, then is the function of wind-break and sand-fixing, the purifying atmosphere function is worst.