Study On The Characteristics Of Forest Distribution In North Shanxi Province During The Historical Period

North Shanxi is located in the southern part of the farming-pastoral ecotone of northern China,and it was alternately controlled by the farming and nomadic regimes in the history.The distribution of forests in this region has a special relationship with the changes of dynasty.The special distribution characteristic of the forests offers significant potential for restoration of forests and ecological construction.It can not only reveal the evolution of the man-land relationship,but also indicate the status of the present forests.This paper collects a large amount of historical data to analyze the changes of the forest ecosystem in north Shanxi since the Qin and Han Dynasties,and studied the causes of the changes and the responses of the forest ecosystem after being disturbed.Besides,the pattern of the forest ecosystem evolution during the historical period is also summarized.Based on the response relationship between soil and vegetation,the quality of the soil in North Shanxi was estimated and the evolution pattern of soil and vegetation was inferred.Then,with the support of GIS technology,considering the change pattern of forest ecosystems in north Shanxi,the evolution pattern of vegetation in north Shanxi,and the human activity intensity in north Shanxi,the simulations of the spatial distribution of forests in north Shanxi during the historical period was performed.The results indicate that:(1)Since the Qin and Han Dynasties,the forest ecosystem of north Shanxi has been continuously degraded.Until the founding of the People's Republic of China,forest condition in north Shanxi has begun to turn better.Ecological degradation is mainly caused by various human activities.Agriculture,grazing,burn,reclamation,military destruction and external use of wood are the main reasons for the destruction of forest ecosystem in north Shanxi.Destruction of forests by human activities changed the status of forest ecosystems in north Shanxi during the historical period.After the founding of the People's Republic of China,the improvement of the forestecosystem is also related to human activities.The main reason is that human beings begin to pay more attention to the environment.Protecting the remnants of forests and planting trees in great efforts made the forests of north Shanxi gradually improved after the founding of the People's Republic of China.(2)In the historical period,when the forest was in good condition,brown soil was the most ideal type of soil in north Shanxi.With the continuous destruction of forests,the vegetation of mixed coniferous and broad-leaved forests has gradually evolved into grass and even wasteland.Meanwhile,the brown soil was gradually replaced by chestnut brown soil,chestnut soil and even coarse bone soil.Soil and vegetation are continually adapted and changed by each other.Although this process has a time lag,it shows consistent relationship from the long-term scale of more than 100 years.(3)The spatial distribution of forests in north Shanxi was influenced by many natural and human factors in the historical period.Based on the combination of qualitative and quantitative analysis,the spatial pattern of forests has been traced back to historical time under the constraints of present vegetation and soil patterns.Through GAP analysis on the simulation map and the current status map of the spatial distribution of forests,it was recognized that the present situation of forest in north Shanxi is slightly better than the Yuan Dynasty,but it is still sparse and in poor quality.Therefore,in the future restoration of forests in north Shanxi,We should focus on the protection of the existing natural forests and strictly control the intensity of human activities.In addition,forest recovery can be combined with soil recovery to guide the two to form a virtuous cycle.At the same time,the rational planning and distribution of land use is also necessary for the reconstruction of a complete forest ecosystem in north Shanxi.As far as the study of this article is concerned,the simulation of the spatial distribution of forest in north Shanxi is still in the preliminary stage of discussion.Based on the limited historical data,the changes of the forest ofthe six historical periods in north Shanxi were analyzed.And based on the analysis of soil-vegetation response relationship,the evolution model of soil and vegetation in north Shanxi is speculated.Then the restoration map of forest of three time sections in north Shanxi is simulated.The three time sections include the end of the Han Dynasty,the end of the Yuan Dynasty and the end of the Ming Dynasty.In future research,it is urgent and necessary to excavate more continuous and detailed historical data,and introduce more advanced quantitative analysis and spatial analysis technology,as well as more detailed and accurate simulation methods.