生态保护背景下奈曼旗土地利用与景观格局变化

LAND USE AND LANDSCAPE CHANGE UNDER ECOLOGICAL PROTECTION IN NAIMAN BANNER

根据1985年和2000年的2期土地利用图形数据,运用地理信息系统(GIS)技术,数理统计方法和景观生态学方法,研究了生态保护背景下科尔沁沙地奈曼旗土地利用及其景观格局的新变化。结果表明:20世纪80年代以来,由于重大生态保护工程的实施,奈曼旗草地防护林面积,退耕还林面积,以及植被恢复的面积皆有明显提高,尤其是林地面积增长最为显著,增幅达186%;同时,人口增长,耕地需求扩大,造成土地压力过重,因此,局部地区毁林开荒,滥垦草地,导致土地退化的现象依然严重;此外,水稻的引种,大面积的河滩被开发为水田,从而导致水域减少。从景观格局的变化看,林地最为显著,随着斑块数目的剧增,其景观破碎度由0 0178上升至0 1246,耕地、未利用地和水域的破碎度也有所升高,而草地和城乡工矿居民用地的景观破碎度稍有降低;分维数分析表明,林地的斑块形状日趋规整,其它地类变化不甚明显;草地、耕地、林地,以及未利用地间的相互转化,尤其是林地的迅速增加,使林地的景观优势度由0 0336上升至0 1488,是原来的4 4倍,而其它地类的优势度皆有不同程度的下降;就整体景观而言,破碎度和多样性指数皆明显上升。

Based on digital land use maps of 1985 and 2000,the land use and landscape change under ecological protection in Naiman county,Horqin Desert,were studied,exerting geographical information system (GIS),statistics and landscape ecology methods.The result indicated that after the implementation of several ecological projects,the area of forest increased by 186% attributable to the construction of protection forest in grassland and the return of forest from farmland.Furthermore,the regeneration of natural vegetation was also obvious in unused land.However,with the growth of population and due to deforestation and the reclamation of grassland,land degradation was still serious in Naiman county for greater land pressure.In addition,water area reduced as large amount of beach was exploit for paddy field with the plantation of rice.As for the change of landscape pattern,forest was most important.The sum of forest patches increased to 1009 in 2000 from 144 in 1985 and the fragmentation degree increased from 00178 to 01246 correspondingly,showing the enhancement of forest fragmentation degree.Meanwhile the fragmentation degree of cultivated land,unused land and water increased slightly while that of grassland and construction land decreased slightly.Fractal dimension analysis indicated that,the patch shape of forest was becoming regular while that of other categories changed little compared with 1985.With the interchange among individual categories,the dominant degree of forest increased to 01488 in 2000 from 00336 in 1985 while other categories decreased differently.Finally,the most significant change of the whole landscape was that the fragmentation degree increased to 05429 in 2000 from 0411 in 1985 due to increased number of patches.