Monitoring of changes in woodlots outside forests by multi-temporal Landsat imagery

Abstract

Woodlots outside forests play a significant role in diversifying household income, reducing poverty, supplying timber and fuel-wood, and regulating the local environment in many countries with low forest cover. This study aimed to develop a method for delineating the spatial footprint of woodlots outside forests and assessing their changes over time. The test site was located in the Jhalokati District of south-western Bangladesh, one of the world’s most densely populated regions. Landsat images from 2010 were classified using a supervised method. Woodlots were extracted, converted to vector layers, and manually edited. The overall accuracy of the 2010 land cover map was 87%-89%. A change vector layer was generated by further updating of the vector layer by overlaying a 1989 Landsat image. The total coverage of woodlots in the district increased between 1989 and 2010, from 19.638 ha (27%) to 27.836 ha (39%). The study identified two primary reasons for changes in woodlot coverage: (i) woodlot expansion associated with the population growth and establishment of new households; and (ii) conversion of cropland to orchards because of economic reasons. The results will improve understanding of the spatial distribution of woodlot coverage in the study area and their dynamics over time.

Keywords

• Woodlot
• Trees Outside Forests (TOF)
• Landsat
• Change
• Mapping