Decadal land cover change dynamics in Bhutan

• We show land cover change in Bhutan from 1990–2000–2010 using Landsat images (30 m).
• Forest area increased over 20 years by 1174 km2 with almost no loss.
• Reasons for forest increase include annual plantation and better management plans.
• The very small increase in settlement area links to low annual population growth.
• The study provides baseline information for other applications.

Land cover (LC) is one of the most important and easily detectable indicators of change in ecosystem services and livelihood support systems. This paper describes the decadal dynamics in LC changes at national and sub-national level in Bhutan derived by applying object-based image analysis (OBIA) techniques to 1990, 2000, and 2010 Landsat (30 m spatial resolution) data. Ten LC classes were defined in order to give a harmonized legend land cover classification system (LCCS). An accuracy of 83% was achieved for LC-2010 as determined from spot analysis using very high resolution satellite data from Google Earth Pro and limited field verification. At the national level, overall forest increased from 25,558 to 26,732 km2 between 1990 and 2010, equivalent to an average annual growth rate of 59 km2/year (0.22%). There was an overall reduction in grassland, shrubland, and barren area, but the observations were highly dependent on time of acquisition of the satellite data and climatic conditions. The greatest change from non-forest to forest (277 km2) was in Bumthang district, followed by Wangdue Phodrang and Trashigang, with the least (1 km2) in Tsirang. Forest and scrub forest covers close to 75% of the land area of Bhutan, and just over half of the total area (51%) has some form of conservation status. This study indicates that numerous applications and analyses can be carried out to support improved land cover and land use (LCLU) management. It will be possible to replicate this study in the future as comparable new satellite data is scheduled to become available.

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