嘉陵江中上游林地资源与地形因子时空变化研究--以四川省武胜县为例

嘉陵江中上游林地资源丰富,研究林地资源结构、分布与地形因子之间的关系,对嘉陵江生态保护具有重要意义。利用1998年、2018年Landsat TM遥感影像和DEM数据,采用最大似然分类法、DEM数据栅格表面分析、重分类处理与空间叠加进行林地资源空间演变受地形因子的影响研究。嘉陵江中上游林地资源面积以318.43 hm^2·a^?1的速度显著增加,林地资源类型中有林地平均增加速率最快,正向增加明显的有林地、宜林地和苗圃地与疏林地、未成林地和无林地速率大小不一;林地资源结构呈现出以水土保持林、水源涵养林的柏木(Cupressus funebris)和巨桉(Eucalyptus grandis)为主,经济林中的橙为辅的特征;林地资源主要集中在缓坡坡度、低海拔丘陵和下坡坡位上,无坡向分布区域极少;林地资源转移速率在下坡坡位、低海拔丘陵和西南、东南坡向正、负转移速率最快和最大;各林地类型分布指数在不同地形上差异较大,总体以斜坡、下坡位为绝对优势位,平坡、无坡向为相对劣势位;偏相关分析表明,坡度、海拔、坡向、坡位与林地资源总量分别为负相关、正相关、正负交替、负相关的关系,但与有林地、灌木林地、苗圃地正相关关系较明显。基于林地资源总量、结构与地形因子之间的空间关系,可较好地了解嘉陵江中上游林地资源分布情况,为后期生态修复、生态结构调整提供参考依据。

Temporal and Spatial Changes of Forest Land Resources and Topographical Factors in the Middle and Upper Reaches of the Jialing River:A Case Study in Wusheng County,Sichuan Province

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.