Monitoring sustainability in tropical forests: how changes in canopy spatial pattern can indicate forest stands for biodiversity surveys

Sustainable management of tropical forests has been identified as one of the main objectives for global conservation and management of carbon stocks. Toward this goal, managers need tools to determine whether current management practices are sustainable. Several international initiatives have been undertaken for the development of criteria and indicators to aid managers in moving toward sustainable practices. Despite these efforts, the question of how to apply and assess indicators remains to be answered from an operational, field-based perspective. Field surveys are expensive and time-consuming when management areas are large and in the face of logistical constraints. Thus, there is a need for an approach to prioritization. We sought to determine whether satellite imagery can be used, in conjunction with standard forest management data, to identify and rank priority areas for field surveys of bioindicators. The study area in Costa Rica, in forest areas managed by the Fundacion para el Desarrollo de la Cordillera Volcanica Central (FUNDECOR), was imaged by the Landsat-5 Thematic Mapper in 1986 and 2001. Through spatial statistical analysis applied to the wide dynamic range vegetation index, we were able to quantify and rank changes in canopy spatial structure. The resulting categories can be used by forest managers to identify which areas are in need of field surveys. More generally, we show how to generate a moving baseline for change analysis and evaluate for significant deviations in spatial structure