Multiscale spatial variation of the bark beetle Ips sexdentatus damage in a pine plantation forest (Landes de Gascogne, Southwestern France)
PIOU, Dominique
Biodiversité, Gènes & Communautés [BioGeCo]
Département de la Santé des Forêts [DSF]
< Réduire
Biodiversité, Gènes & Communautés [BioGeCo]
Département de la Santé des Forêts [DSF]
Langue
en
Article de revue
Ce document a été publié dans
Forest Ecology and Management. 2009, vol. 257, n° 7, p. 1551-1557
Elsevier
Résumé en anglais
Bark beetles are notorious pests of natural and planted forests causing extensive damage. These insects depend on dead or weakened trees but can switch to healthy trees during an outbreak as mass-attacks allow the beetle ...Lire la suite >
Bark beetles are notorious pests of natural and planted forests causing extensive damage. These insects depend on dead or weakened trees but can switch to healthy trees during an outbreak as mass-attacks allow the beetle to overwhelm tree defences. Climatic events like windstorms are known to favour bark beetle outbreaks because they create a large number of breeding sites, i.e., weakened trees and for this reason, windthrown timber is generally preventively harvested and removed. In December 1999, the southwest of France was struck by a devastating windstorm that felled more that 27 million m3of timber. This event offered the opportunity to study large-scale spatial pattern of trees attacked by the bark beetle Ips sexdentatus and its relationship with the spatial location of pine logs that were temporally stored in piles along stand edges during the post-storm process of fallen tree removal. The study was undertaken in a pure maritime pine forest of 1300 ha in 2001 and 2002. We developed a landscape approach based on a GIS and a complete inventory of attacked trees. During this study more than 70% of the investigated stands had at least one tree attacked by I. sexdentatus. Spatial aggregation prevailed in stands with n≥15 attacked trees. Patches of attacked trees were identified using a kernel estimation procedure coupled with randomization tests. Attacked trees formed patches of 500–700 m2 on average which displayed a clumped spatial distribution. Log piles stemming from the sanitation removals were mainly distributed along the large access roads and showed an aggregated spatial pattern as well. The spatial relationship between patches of attacked trees and log pile storage areas was analyzed by means of the Ripley’s statistic that revealed a strong association at the scale of the studied forest. Our results indicated that bark beetle attacks were facilitated in the vicinity of areas where pine logs were stored. The spatial extent of this relationship was >1000 m. Similar results were obtained in 2001 and 2002 despite differences in the number and spatial distribution of attacked trees. The presence of a strong “facilitation effect” suggests that log piles should be removed quickly in order to prevent outbreaks of bark beetles.< Réduire
Mots clés
PINUS PINASTER
SPATIAL STATISTICS
PLANTATION FOREST
INSECTE
COLÉOPTÈRE
STATISTIQUE DE RIPLEY
TEMPÊTE DE 1999
TEST DU CARACTÈRE ALÉATOIRE
LANDES DE GASCOGNE
RÉPARTITION SPATIALE
Mots clés en anglais
IPS SEXDENTATUS
BARK BEETLE
RIPLEY’S STATISTIC
AGGREGATION
LANDSCAPE
PIN MARITIME
ZONE DE STOCKAGE
Origine
Importé de halUnités de recherche