摘要
退耕还林和天然林保护等重大林业生态工程的实施对我国西部地区生态环境建设起到了积极的推动作用。植被的重建、恢复和保护,不仅改变了景观的类型组成,也强烈地影响着景观的空间构造。以四川盆地山地丘陵区边缘的四川省洪雅县为研究对象,采用景观生态学原理和方法,对工程实施前后15年来(1994—2009)洪雅县景观格局的变化进行分析,探讨了植被恢复对景观格局的影响。结果显示,林地增加、耕地和草地减少,是15年间洪雅县景观变化的主要特点。耕地的减少和林地的增加主要集中于人为活动影响更为强烈的海拔1000 m以下区域,反映了退耕还林对景观类型组成改变的巨大推动作用;海拔1500 m以上区域,更多地受到天然林保护和自然因素影响,面积变化相对稳定,景观格局空间构造方面的变化更为显著;海拔1000—1500 m区域,两种工程实施的影响交错,过程相对复杂。坡度≤5°的平缓地中,人为活动影响强烈,林地增加明显;而在坡度25°附近的坡地中,耕地较多,退耕还林潜力较大,耕地—林地转换相对其他坡度区段更为明显。总体上,林地向低海拔、缓坡度区域扩张,斑块间空隙还林面积较多,有连片发展趋势;而耕地在面积减少的同时,向低海拔、缓坡度区域收缩,斑块规模更小,格局更加破碎。
Great forestry ecological engineerings, Conservation （NFC）, have played positive roles in i.e. Conversion of Farmland to Forest （CFF） and Natural Forest promoting the ecological environment constructions in western China The restoration of vegetation in these projects changed pattern. In this paper, the landscape pattern of Hongya not only the composition but also the configuration of landscape Country in 1994 and 2009 were compared to examine the effects of vegetation restoration on landscape pattern in the mountain-hilly region of the edge of Sichuan Basin, China. Landscape patterns at the two periods were both derived from Landsat TM images using a supervised classification procedure. The area of vegetation types were compared to examine the spatial distribution changes at different elevation and slope zones, and six landscape pattern indices were calculated to quantify the changes of landscape pattern at both landscape and class level. The elevation and slope zones were classified with the step sizes of 500m and 5° respectively, and the indices were calculated in Fragstats 3.4. From 1994 to 2009, the total area of forest in and grassland decreased by 5.12% and 1.51% Hongya increased by 5.72% from 60.58% to 66.30%, and the farmland respectively. The increase of forestland and decrease of farmland andgrassland are the major effects of vegetation restoration. Most of the conversions from farmland to forestland occurred under the elevation of 1000m, indicating a remarkable promotion of CFF to the change of landscape composition. Furthermore, as the dominant type, forest occupies more than 80% of total area in the region higher than 1500m. The vegetation restoration here was mainly influenced by the NFC and natural conditions, exhibiting little change of amount, but more change of landscape configuration. In region between the elevations of 1000m and 1500m, the amounts of both forestland and farmland were relatively stable, but remained some farm-forest conversions, and the landscape changes here were more complex, partly for the overlapping influences of CFF and NFC. At the slope aspect, forest in the region ≤ 5° increased obviously for the intense impact of human activities; moreover, in the region of near 25° forest also exhibited a little increasing trend, indicating more potential conversions from farmland to forest in the implement of CFF. The overall landscape pattern change of Hongya exhibited a little defragmentation trend from 1994 to 2009. For farmland, influenced by CFF, patches were cut apart and converted to forest, resulted in more patches and smaller mean patch size, and the patches were more fragmented. While, forest was influenced by both the CFF and NFC, the gaps between forest patches were more filled, resulted in fewer patches and larger mean patch size, and the patches were more expanded and aggregated. In summary, as the consequences of vegetation restoration, forest was more continuously expanded to areas with lower elevation; while farmland was more shrunk, and its pattern was more fragmented. At last, different change processes can result in different composition and configuration changes of landscape pattern. The method of traditional landscape pattern analysis cannot distinguish various processes of landscape change, in which the landscape and class level indices are indistinct and uninterpretable. There is a need to develop novel approaches to analysisthe changes of landscape pattern for various change processes, especially for the interpretation of landscape indices.
出处
《生态学报》
CAS
CSCD
北大核心
2013年第20期6721-6729,共9页
Acta Ecologica Sinica
基金
国家"十一五"
"十二五"科技支撑计划项目(2006BAD23B05
2011BAC09B05)
关键词
植被恢复
退耕还林
天然林保护
洪雅县
景观变化
vegetation restoration
conversion of farmland to forest
natural forest conservation
Hongya country
landscape change
