| Due to the influence of natural and human factors,forest ecosystems in high-frequency disturbed areas have complex changes on different spatial-temporal scales.It is of great significance to build effective models based on remote sensing time series data to capture,describe and reveal the multi-scale dynamic changes of ecosystem and the interaction between ecosystem and environment.However,most of the existing algorithms have some shortcomings,such as separating the spatiotemporal correlation,less considering the spatiotemporal neighborhood characteristics and so on,which makes it difficult to accurately and comprehensively describe and quantify the spatiotemporal complex change characteristics of the surface.To solve this problem,this study attempts to establish a forest dynamic monitoring model which makes full use of spatiotemporal context information(1)In order to solve the problem that the disturbance frequency of high-frequency disturbance area is low but its intensity is low,and its impact on forest appearance is not obvious,a spatiotemporal cube(ST-cube)and vegetation index(VI)were combined to establish a spatiotemporal multi-scale forest ecosystem change detection model,IST-cube(improved spatiotemporal cube).IST-cube model is sensitive to the changes of forest function and structure,and can make full use of spatiotemporal information to effectively generate multi-scale cubes.It has reliability and superiority in analyzing the spatiotemporal characteristics of forest.(2)The model was used to obtain the spatiotemporal dynamics of forest ecosystem in the study area,and it was divided into four spatiotemporal scales:long-term large-scale IST-cube,long-term small-scale IST-cube,short-term large-scale IST-cube short-term small-scale IST-cube.Furthermore,Mann–Kendall test,Theil Sen slope estimation and dynamic time warping algorithm are used to further analyze the trends and rules of IST-cube s at four scales,effectively depicting the spatiotemporal characteristics of different spatiotemporal scales in high-frequency disturbance areas,and revealing the change rules of forest function and structure.(3)Taking Shizhuyuan mining area in southeastern Chenzhou City of Hunan Province as the research area,and taking the Landsat images from 1987 to 2020 as the data source,the spatiotemporal dynamics of forest were captured by IST-cube model.The results showed that cube core only existed in the growing IST-cubes,mainly distributed in residential areas and forests.Human activities lead to a long-term and small-scale IST-cubes,and the impact on the neighborhood is increasing,but there is no change within the neighborhood.The impact of meteorological disasters is short-term,large-scale and irregular.Land use type change has short-term,small-scale IST-cubes and regular impacts. |
