1987—2015年泰国—老挝边境地区自然林减少及其转换特征

Natural forest loss and its transformation characteristics along the Thailand-Laos border during 1987-2015

地缘经济合作已经或正在驱动国家间边境地区土地利用变化,但其互动关系(如影响-响应)定量研究仍显不足。利用美国国际开发署SERVIR-Mekong项目土地覆被产品,基于ArcGIS研究了泰老两国边境地区1987—2015年自然林减少及其向农田和种植园的转换过程与特征。结果表明:(1)泰老边境地区近30年自然林(含森林与混交林)减少3.18×104 km2。其中,泰国一侧以农田转换为主,减幅72%;老挝一侧以种植园转换为主,减幅超2/3强。(2)2000年前后(1999—2003年)边境两侧自然林减少最为显著,占比2/5,且集中发生在边境城镇(万象)或口岸(泰国清孔、廊开口岸)地区。(3)泰老边境两侧森林/混交林减少量距国界越近规模越大,趋边性明显。其中老挝一侧因农田扩张的森林/混交林毁林、因种植园增加的森林转出尤甚;而泰老两侧因种植园转换的混交林毁林则表现为强趋同性。(4)因农田扩张造成的森林/混交林减少集中在泰老边境两侧45 km以内,而种植园扩张引起的森林(13 km以内)较混交林毁林趋边更显著。

Geo-economic cooperation has driven or is driving land use/cover changes in national border areas globally.However,quantitative examination of bilateral impact-response and their relationship remains insufficient,or in an initial stage.Using the SERVIR-Mekong land-cover products provided by the United States Agency for International Development,the loss of natural forest and its transformation processes towards cropland and plantations(including orchards)as well as their border-proneness in the border area(a buffer of 60 km)of Thailand and Laos from 1987 to 2015 were analyzed with GIS-based methods.The results showed:(1)Over 3.18×104 km2 of natural forest(including forest and mixed forest)loss was seen in the border areas in the past 30 years.The forest loss driven by farmland expansion in the Thai side was dominant,with a reduction of 72%;while the plantations(including orchards)caused over 2/3 of forest loss in the Laotian side.(2)Deforestation due to the expansion of cropland and plantations was significantly notable circa 2000,or between 1999 and 2003 in both sides,accounting for over 40%,which was concentrated in the surrounding area of major border cities(e.g.,Vientiane)or crossing ports(e.g.,Chiang Khong and Nongkhai,Thailand).(3)The loss amount of forest and mixed forest on both sides increased as it gets closer to the borderline.The deforestation of forest and mixed forest due to farmland conversion and the conversion of forest into plantations(including orchards)in the Laotian side displayed a more obvious border-proneness;while the deforestation of mixed forest because of the conversion into plantations(including orchards)in both sides displayed strong convergence.(4)The forest/mixed forest reduction caused by the expansion of farmland was primarily seen within 45 km on both sides,while the forest loss(within 13 km)caused by the expansion of plantations(including orchards)was more significant than that of mixed forests.