Abstract:
There are many forest land resources in the middle and upper reaches of the Jialing River. It is of great significance to study the relationship between the structure, distribution and topographical factors of forest resources for the ecological protection of the Jialing River. Using the Landsat TM remote sensing image and DEM data of 1998 and 2018, this paper studied the influence of topographical factors on the spatial evolution of forest land resources by using the maximum likelihood classification method, DEM data grid surface analysis, reclassification processing and spatial superposition. The area of the forest land resources in the middle and upper reaches of the Jialing River increased significantly at a rate of 318.43 hm
2·a
−1. Among the forest land resources types, the average increase rate of forest land was the fastest, and the positive increase rate of forest land, suitable forest land and nursery land was different from that of sparse forest land, immature forest land and non-forest land. The structure of forest land resources was dorminated by
Cupressus funebris and
Eucalyptus grandis in water and soil conservation forest and water conservation forest, and orange was aided in economic forest. Forest land resources were mainly concentrated on gentle slope, low-altitude hills and downhill slope positions, with very few areas on without aspect distribution. The transfer rate of forest land resources was the fastest and the largest in downhill slope positions, low-altitude hills and southwest and southeast slopes. The distribution index of various forest types was quite different in different topographies. Generally, the slope and downhill position were the absolute dominant positions, while the flat slope and non-slope were the relative disadvantaged positions. Partial correlation analysis showed that slope, altitude, aspect and slope position had negative correlation, positive correlation, positive-negative alternation and negative correlation with the total amount of forest land resources respectively, but had obvious positive correlation with forest land, shrub land and nursery land. Based on the study of the spatial relationship between the total amount, structure and topographic factors of forest land resources, the distribution of forest land resources in the middle and upper reaches of the Jialing River could be better understood, providing reference basis for ecological restoration and ecological structure adjustment in the latter stage.