| Forestland is the carrier of various ecological functions such as water conservation and biodiversity maintenance,which is of great significance to regional and even global green and sustainable development.The change of forestland is a continuous quantitative change in time,that is the increase or decrease of forestland area,and it is manifested as a continuous change of spatial structure and pattern in space.It is of great significance to study the law of spatial-temporal distribution of forestland,and to explore the influencing factors of the changes and spatial distribution of natural forests and plantations,so as to provide reference for rational utilization of forestland resources and to make scientific and effective forestland management measures.Based on the forest resource survey data and the natural and social economic data of Nanning city in 2008,2013 and 2018,this paper applied spatial statistical techniques to analyze the quantitative structure of forestland and changes in the spatial and temporal patterns.The spatial and temporal dynamics of forestland in Nanning City from 2008 to 2018 were analyzed,and the important factors affecting the changes and spatial distribution of natural forests and plantations in the study area were explored by combining the spatial lag model and the geographic detector model.The following main findings were drawn:(1)From 2008 to 2018,the overall area of forestland in Nanning decreased by 2.77×10~4hm~2.The area of plantation increased by 2.6×10~4hm~2,that of natural forest decreased by 2.39×10~4hm~2,and that of other forestland decreased by 2.98×10~4hm~2.Second,the changes of forestland in 2013-2018 were more complicated.The dynamic attitudes of natural forests,plantations and other woodlands in 2013-2018 were significantly higher than those in 2008-2013.Spatially,during 2013-2018,the conversion between natural forests and plantations and between forestland and non-forestland became more fragmented and complex,with the conversion plots scattered and the conversion area greatly increased.(2)The spatial distribution of natural forests and plantations in Nanning both had significant spatial autocorrelation(P<0.01).The spatial aggregation of natural forest was higher than that of plantation forest,and there was a trade-off relationship between them.However,from 2008 to 2018,the spatial autocorrelation of natural forest and plantation both gradually decreased,and the trade-off relationship between them gradually weakened.In the local Moran’I scatter plots of natural and planted forests in 2008,2013 and 2018,most of the natural and planted forests showed high-high or low-low aggregation.(3)Socio-economic factors were important driving forces affecting forestland changes.In principal component regression,socioeconomic factors had a negative effect on the growth of natural and planted forests.In the factor detector,population density was important factors for natural forest changes,and nighttime light intensity was important driving factors for plantation changes.The interaction of different factors promoted or inhibited forestland changes.(4)Natural factors were important factors that determined the spatial distribution of natural forests,while socioeconomic factors had a greater impact on the distribution of plantations.The spatial distribution of natural forest had a significant positive correlation with the principal component of the natural environment.The spatial distribution of plantation forests was significantly negatively correlated with the socio-economic principal component,but not significantly correlated with other principal components.In the factor detector,the spatial differentiation of natural forest and plantation was affected by the natural environment and social economy,and the most important factor to explain the spatial distribution of natural forest and plantation was slope.The interaction between factors promoted the formation of the spatial distribution patterns of forestland. |
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