Zero Deforestation Agreement Assessment at Farm Level in Colombia Using ALOS PALSAR

Abstract

Due to the fast deforestation rates in the tropics, multiple international efforts have been launched to reduce deforestation and develop consistent methodologies to assess forest extension and change. Since 2010 Colombia implemented the Mainstream Sustainable Cattle Ranching project with the participation of small farmers in a payment for environmental services (PES) scheme where zero deforestation agreements are signed. To assess the fulfillment of such agreements at farm level, ALOS-1 and ALOS-2 PALSAR fine beam dual imagery for years 2010 and 2016 was processed with ad-hoc routines to estimate stable forest, deforestation, and stable nonforest extension for 2615 participant farms in five heterogeneous regions of Colombia. Landsat VNIR imagery was integrated in the processing chain to reduce classification uncertainties due to radar limitations. Farms associated with Meta Foothills regions showed zero deforestation during the period analyzed (2010-2016), while other regions showed low deforestation rates with the exception of the Cesar River Valley (75 ha). Results, suggests that topography and dry weather conditions have an effect on radar-based mapping accuracy, i.e., deforestation and forest classes showed lower user accuracy values on mountainous and dry regions revealing overestimations in these environments. Nevertheless, overall ALOS Phased Array L-band SAR (PALSAR) data provided overall accurate, relevant, and consistent information for forest change analysis for local zero deforestation agreements assessment. Improvements to preprocessing routines and integration of high dense radar time series should be further investigated to reduce classification errors from complex topography conditions. played an especially important role in landscape change dynamics within the country [2]. Currently, ranching represents one of the key economic subsectors in Colombia, contributing to approximately 3.5% of the overall Gross Domestic Product (GDP) and 27% of the agricultural and livestock GDP [3]. Cattle ranching exploited more than 38 million hectares over the last 50 years, holding approximately 23.5 million heads, supporting 7% and 28% of national and rural employment, respectively.Information related to forest trends are critical to different actors involved in the decision-making of policies and investments promoting the conservation of forests and their ecosystem services. Globally, several efforts have been put in place to develop consistent and robust methodologies to assess forest extension and change [4][5][6][7][8][9][10]. As a response to the rapid advance of global forest loss and degradation, the UN Framework Convention on Climate Change (UNFCCC) launched the Reducing Emissions from Deforestation and Forest Degradation program (REDD+). The general aim of REDD+ is to contribute to the mitigation of climate change by reducing greenhouse gas (GHG) emissions by decreasing and reversing forest loss and degradation, and by increasing the removal of GHGs through conservation and the expansion of forests [11]...