Monitoring of bark and wood-boring beetles in France after the December 1999 storms

摘要

After the December 1999 storms, two networks were set up over 2 years (2000 and 2001) to assess the scale and type of insect colonisation on storm damaged trees and to interpret these events for the future. The Level 1 network, was a large-scale survey that covered the entire storm area and provided qualitative observations on its 898 plots in which every major tree species was assessed. The Level 2 network, was a regional survey set up only in two regions: the 'Landes' region and the Northeast ofFrance. The observations were intensive and quantitative, devoted only to maritime pine in the 'Landes' region and to Norway spruce in the Northeast of France. The Level 1 network indicated that less than 40 percent of the storm damaged trees were colonised by bark beetles in September 2000. No attacks were observed on standing trees in 2000 but many occurred during 2001 in spruce and maritime pine stands. The Level 2 network in the Vosges mountains showed a late colonisation in October and November 2000. The emerging population of Ips typographus on attacked trees reached 25 000-30 000 insects/m~3. This huge population combined with the low rate of parasitism in 2001 leads to the expectation of increasing damage in spruce stands next year.