From forest trees and stand vulnerability to extreme events to adapative management: lessons from DRYADE national program
Résumé
Dryade project gathers an interdisciplinary consortium of researchers (ecophysiology, ecology, genetic, modeller, remote sensing), people in charge of forest survey (inventory, health status), and managers from both private and state forests. Recent climatic and biotic events induced forest decline in France. Tree and stand responses were quantify through crown condition and tree health monitoring (forest department network, national forest inventory), radial growth (dendroecology) for five major productive species of the French forest. Special attention was paid to interactions between drought and vulnerability to pests (bark beetle, caterpillars) and disease (root and leaf fungi). The objectives were (1) to quantify the impacts of management and physiological vulnerability factors to decline, (3) to build models of vulnerability to growth loss or dieback for each species, (4) map vulnerability factors at national scale to assess the more vulnerable areas within the actual distribution of each species (4) to give recommendations to foresters to adapt forests and management to drought risk increase, either by reducing vulnerability (species or provenances, physiological status) or reducing the intensity of drought (improving water balance by water saving forestry) and biotic hazards (pest and disease control). Abnormal mortality occurs as a combination of extreme climatic and biotic events, misadaptation and mismanagement. A guide for sylviculture during forest decline period was proposed as a tool for developing crisis management