老挝北部5省橡胶林提取及时空扩张研究

目的]分析老挝北部"金三角"地区橡胶林提取方法及橡胶林时空扩张特征,为合理规划橡胶种植、区域生态环境保护等提供方法和依据。方法]基于MODIS影像和橡胶林物候特征,选取不同地类特征参数,实现橡胶林空间分布快速可重复的决策树提取新方法,并基于单一土地利用率模型研究橡胶林扩张机制。结果](1)橡胶林提取时间窗口为1月至3月,基于不同地类特征参数生成的橡胶成林、幼林决策树提取方法总精度为80.67%,高分一号影像通过面向对象方法验证MODIS影像提取结果精度可靠。(2)2010—2015年,老挝北部5省橡胶林由12.6万hm~2扩张到16.96万hm~2,面积变化率最大的是乌多姆赛省,丰沙里省扩张速度最慢。结论]MODIS影像提取橡胶林方法和结果简单有效。橡胶林分布在海拔和坡度上呈现不断上升的趋势,海拔1 500 m以上零星分布,坡度上分布上限为35°,而坡向扩张无明显规律。从LUCC视角分析得到橡胶林时空扩张的主要影响因素是社会政策和经济因素。

Research on Extraction and Spatial-Temporal Expansion of Rubber Forest in Five Provinces of Northern Laos Based on Multi-source Remote Sensing

Objective] The aim of this research is to analyze the extraction method of rubber forest in the "Golden Triangle" region of northern Laos, to monitor the rubber forest and its spatial expansion dynamically, and to provide methods and lay a basis for rational planning of rubber planting and regional ecological environment protection.Method] A new method for rapid and repeatable extraction of rubber forest spatial distribution was used based on MODIS remote sensing data, the phenological characteristics and the geometric parameters of rubber forest, and the expansion mechanism of rubber forest was analyzed based on single land use rate model.Result] (1) The rubber tree extraction ranged from January to March. The precision of extraction method based on phenological characteristics and geometric parameters was 80.67%. GF-1 images were classified by the object-oriented method to verify the MODIS data which proved to be reliable. (2) The area of rubber forest in five provinces of northern Laos was expanded from 12.6×10⁴ hm² to 16.96×10⁴ hm² between 2010 and 2015. The area of rubber forest changed the most in Oudomxay province, and the least in Phongsaly province.Conclusion] The method to extract rubber forest by MODIS data is simple, valid and effective. The distribution of rubber forests increases with the elevation and slope and scatters over the elevation of 1500m, the upper limits of slope is 35°. While, no obvious rule about distribution on the aspect is found. The main factors influencing the spatial and temporal expansion of rubber forest are social policy and economics from the perspective of LUCC.