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.