MAPPING FOREST-COVER DISTURBANCES IN PAPUA-NEW-GUINEA WITH AVHRR DATA

Land management and land-use planning in a forested country such as Pa pua New Guinea, which is subject to various anthropogenic pressures, r equires an accurate mapping of forest-cover disturbances. The central hypothesis of this study was that remote sensing indicators of forest- cover conditions can be used to measure and map the impact of long-ter m forest-cover disturbances. This was tested with single year NOAA's A dvanced Very-High Resolution Radiometer sensor (AVHRR) data at 1.1 km resolution. First, an ordinal scale of forest-cover disturbance was de fined from field observations, a set of thematic maps and high spatial resolution satellite sensor data. Secondly, we analysed the relations hip between the forest-cover disturbance scale and several biophysical indicators derived from AVHRR data at two seasons. Thirdly, a statist ical analysis identified the optimal combination of biophysical indica tors and observation dates to discriminate between the forest disturba nce levels defined previously. A forest cover disturbance map was then produced over part of Papua New Guinea. Finally, a regionalization of the study area in terms of aggregate degree of disturbance was produc ed and the spatial patterns of forest disturbances were interpreted fo r each region in terms of broad processes of forest-cover change. The overall accuracy of the forest cover disturbance map was 79%. Nine reg ions, homogeneous in regard to the distribution and spatial pattern of disturbance categories, were identified.