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Assessing the state of the tropical forests is relevant for studying the impact of human activities on the global environment. This paper presents a new approach for global humid tropical forest monitoring using Earth observation techniques. The approach is based on intensive sampling with high resolution satellite data, focusing on the most active deforestation areas.

As a first step, the humid tropical forest belt was mapped using coarse spatial resolution AVHRR imagery in the early 90's, using high-resolution satellite data (mostly Landsat TM) as a reference data source. The 1.1 km spatial resolution of AVHRR is well adapted to the geographic scale of the monitoring exercise. However, this spatial resolution leads to a loss of detail that makes it difficult to derive a good proxy variable for the measurement of deforestation rates.

At the pan-tropical level a new sampling scheme for forest change assessment, using high-resolution satellite images, has been defined using sampling units independent of any particular satellite sensor. For this purpose an equal probability sampling frame has been chosen (a hexagonal tessellation on a sphere). To reduce the variance of the stipulated variable, a stratification has been performed using two parameters: the forest cover area (based on the AVHRR map) and the 'deforestation hot spot' delineation (based on an international consultation). Ninety-five sites have been selected over the three continents and pairs of high resolution imagery are being analysed to estimate humid tropical forest cover change during the period 1992-1997.

Additional information

Authors: ACHARD F, Space Application Institute, JRC Ispra (IT);EVA H, Space Application Institute, JRC Ispra (IT);MAYAUX P, Space Application Institute, JRC Ispra (IT);RICHARDS T, Space Application Institute, JRC Ispra (IT);STIBIG H, Space Application Institute, JRC Ispra (IT)
Bibliographic Reference: ORA, Conference of Remote Sensing and Forest Monitoring, 1-3/06/1999, Rogow, (PL) (2000) pp 200-20,
Availability: 1 as paper EN 60114 ORA
Record Number: 200012836 / Last updated on: 2000-11-07
Original language: en
Available languages: en