The contribution of remote sensing to the assessment of drought effects in forest ecosystems
Ann. For. Sci.
The contribution of remote sensing to the assessment of drought effects in forest ecosystems
Michel D 4
Dominique G 2
Hervé J 3
Nicolas S 0
Anne J 1
Olivier H 3
0 Inventaire Forestier National , 32 rue Léon Bourgeois, 69500 Bron , France
1 Office National des Forêts , Sylvétude Lorraine, 5 rue Girardet, 54052 Nancy Cedex , France
2 INRA, Unité de Recherche Écologie fonctionnelle et Physique de l'Environnement , BP81, 33883 Villenave d'Ornon , France
3 CNES , 18 avenue Edouard Belin, 31401 Toulouse Cedex 9 , France
4 ENGREF, UMR Territoires, Environnement, Télédétection et Information Spatiale , Cemagref-CIRAD-ENGREF, 500 rue JF Breton, 34093 Montpellier Cedex 5 , France
- Due to their synoptic and monitoring capacities, Earth observation satellites could prove useful for the assessment and evaluation of drought effects in forest ecosystems. The objectives of this article are: to briefly review the existing sources of remote sensing data and their potential to detect drought damage; to review the remote sensing applications and studies carried out during the last two decades aiming at detecting and quantifying disturbances caused by various stress factors, and especially those causing effects similar to drought; to explore the possibility to use some of the different available systems for setting up a strategy more adapted to monitoring of drought effects in forests. drought / forest / remote sensing / satellite Résumé - Contribution de la télédétection à l'évaluation des effets de la sécheresse sur les écosystèmes forestiers. Grâce à leurs capacités de surveillance continue, les satellites d'observation de la Terre pourraient s'avérer utiles pour l'évaluation des effets de la sécheresse sur les écosystèmes forestiers. Les objectifs de cet article sont : de passer en revue rapidement les sources actuelles de données de télédétection et leur potentiel pour la détection des dommages dus à la sécheresse ; de passer en revue les études et applications de télédétection conduites pendant les deux dernières décennies et visant à détecter et quantifier les perturbations induites par différents facteurs de stress, et en particulier ceux causant des effets semblables à ceux de la sécheresse ; d'explorer la possibilité d'utiliser certains des systèmes disponibles pour définir une stratégie adaptée au suivi continu des effets de la sécheresse sur les forêts.
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Review
sécheresse / forêt / télédétection / satellite
1. INTRODUCTION
Earth observation satellites have been used for more than
30 years for land cover mapping and forest monitoring. Most
of platforms have been developed by state-owned space
agencies. Commercial systems with very high resolution
capabilities, mainly in the optical domain, have been developed for
addressing specific markets, e.g. urban mapping, rapid
mapping after natural disasters and defence needs.
In 2005, more than 60 Earth observation satellites are in
operation and are providing relevant information of the planet
environment, about half of them carrying dedicated sensors
for land and vegetation observation at different resolution and
spectral capabilities [
17
]. This wide range of Earth observation
systems offers in principle large possibilities for forest
applications, but leads at the same time to specific problems on data
compatibility, calibration, geometry and continuity.
No Earth observation system is fully dedicated to monitor
and quantify the impact of extreme climatic situations such as
the severe heat and drought of 2003 and a very limited
literature on such situations is available in temperate climate,
especially in Europe, specifically on drought effects.
The aims of this article are:
(1) To briefly review the existing sources and useful physical
principles of remote sensing. The observable biophysical
variables and processes are presented.
(2) To review the remote sensing applications and studies
carried out during the last two decades aiming at detecting and
quantifying disturbances caused by various stress factors.
The potential use of earth observation data for detecting
drought effects can be, with some limitations, derived from
the similarity of the detected changes with those caused by
drought.
This part gives an overview of the state of the art in
the use of remote sensing for detecting and
monitoring forest changes and drought effects. The first section
outlines the capability of remote sensing to detect and
track rapid vegetation structure changes such as clear
cutting or storm damages. Fire-related disturbances, a very
important and specific issue in forest management, are not
considered here. The following sections deal with
monitoring of changes resulting from continuous and progressive
mechanisms, such as forest decline or phenological
disturbance or productivity reduction, with a focus on vegetation
anomalies due to drought and water stress. The last section
addresses the future prospects given by t (...truncated)