Relation entre la composition floristique et des indicateurs de la fragmentation du paysage dans une région de transition forêt-savane ivoirienne

Abstract

Relation between floristic composition and landscape fragmentation indicators in a transition forest-savanna area of Côte d'Ivoire. Forest landscape fragmentation is known to be a significant factor of forest degradation. In this article, we analyze the case of forest-savanna contact of East Côte d'Ivoire, where savannas progress quickly to the detriment of forests. Using forest inventories and the spectral and spatial properties of a Landsat ETM+ image, we established the existence of two independent floristic gradients within forests, which were correlated to various aspects of forest fragmentation. The main floristic gradient was correlated with the degree of opening of forest stands and with the abundance of heliophilics. Spectrally, this gradient clearly correlates with a variation in the red and near infra-red bands. In terms of landscape structure, it is significantly related on the size and the isolation of small forest patches. A second floristic gradient is correlated to the perimeter of forest fragments, and may thus reflect an edge effect. These results make it possible to consider an operational approach based on multispectral data of average resolution and pattern metrics for operational assessment and monitoring of forest degradations on regional scales.

Keywords

• Forest fragmentation
• landscape shape metrics
• floristic composition
• edge effect
• remote sensing
• forest-savanna contact
• Côte d'Ivoire