| We hypothesized grassland (interspersed with grass and forest) as the study object, and referred the related statistical books: the Statistical Yearbooks of Shaanxi Province and land-use change datas sets from Department of Land and Recourses of Shaanxi Province from 1996 to 2007 and the field survey as our research data. Based on dynamic changes and analysis model using SPSS, we analyzed spatio-temporal variation of forest and grassland and its anthropogenic driving force during past 12 years in Hanzhong area, the results reveal the regional economic development on ecosystem structure and function of the studied area. We come to some conclusions as follows:(1) Due to the implementation of "Restoring Farmland to Forest or Pasture (RFFP)" policy, the area of grassland presented an increased trend between 1996 and 2007. Within the past twelve years, Nearly 12 years, the area of farmland decreased by 1.43265 million km~2, meanwhile, the area of woodland increased 98.1 thousand km~2 and grassland increased 1.7391 million km~2.The area of other land types maintained the same as before..(2) Spatial distribution of orginal vegetation and artificial (second) vegetation are different. The distributed proportion of woodland, shrubbery, thin stocked land and orginal grassland area is low in the central region and hight in the peripheral part. Yet, the distributed proportion of atrtificial (second) grassland is high in the central, low in the peripheral. The young afforestation land mainly in the peripheral area, hence the change of foresta and grass in this region could contribute 85%.The structure of forest and grassland are changed. The area of forest and grassland increased during the past twelve years, yet 99.90% of the area is young afforestation land, and woodland decreased slightly after 2002 and till 2007, the area shrinked 4923 mu and orginial vegetation also decreased. This perhaps could indicated that anthropogenic pressure has negative impact on orginial vegetation and replace the orginial forest ecosystems with artificial ecosystemsThe analysis on the driving force of forest presented that the land use policy of couty-level plays a major role in the dynamic of forest area, while the economic conditions have the major impacts at city-lelve. Studied on driving force of forest changes showed that for county area of land use, the influence of land use policy changes of the forest area is stronger, while the larger municipal, regional economic vitality is the main influence. Region in the county-level agricultural output and population of the total change in the grass and natural grass more direct influence, and the influence of regional economic vitality to the grass area change is more bigger. Area of farm land and unwoodland was the anti-correlation. Area of water area and woodland was anti-correlation. Per capita GDP and the area of grassland and natural grassland was a positive correlation.The effect of Socio-economic activities on the vegetation area are lagged. The time lag of impact for woodland, unwoodland and natural grassland is 5 years, shrub 3 years. Of sparse forest land, improved grassland, artificial grassland lagging effect for 1 year. These all indicate that the time lage for anthropogenic effect are at least 5 ears or more, especially for the structure of original forest and grass, the effect may be far reaching. Hence, the conservation of forest ecosystem in Qin-ba moundain areas is of great significances, for the sustainability of social, economic and environmental. |
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