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Louis-Michel Nageleisen 《Integrated Pest Management Reviews》2001,6(3-4):159-162
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 of France. 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% 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/m3. This huge population combined with the low rate of parasitism in 2001 leads to the expectation of increasing damage in spruce stands next year. 相似文献
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M.?GilbertEmail author L.-M.?Nageleisen A.?Franklin J.-C.?Gregoire 《Landscape Ecology》2005,20(1):35-49
The storm that struck France on december 26th and 28th 1999 felled 140 million m3 of timber and had a high economic, social and landscape impact. This event offered the opportunity to study large-scale patterns in populations of forest insect pests that would benefit from the abundant breeding material. A large-scale survey was carried out in France in 2000 to sample the most frequently observed species developing on spruce (Ips typographus, Pityogene schalcographus) and pine (Tomicus piniperda, Ips sexdentatus) in 898 locations distributed throughout wind-damaged areas. The local abundance of each species scored on a 0 to 5 scale was analysed using geostatistical estimators to explore the extent and intensity of spatial autocorrelation, and was related to site, stand, and neighbourhood landscape metrics of the forest cover (in particular the interconnection with broadleaf forest patches) found within dispersal distance. All species but I. sexdentatus, which was much less abundant, displayed large-scale spatial dependence and regional variations in abundance. Lower infestation levels per tree (windfalls and standing trees) were observed in stands with a high proportion of wind-damaged trees, which was interpreted as the result of beetles distributing themselves among the available breeding material. More infestations were observed in wind-broken trees as compared to wind-felled trees. More importantly, populations showed significant relationships with the structure of coniferous stands (in particular with the number of coniferous patches). T. piniperda population levels were negatively correlated to the amount of coniferous edge shared with broadleaf forest patches, possibly because of the disruptive effect of non-host volatiles on host-finding processes at the landscape-scale. The differences observed between species regarding patterns and relationships to site, stand, and forest cover characteristics are discussed in relation to the ecological characteristics of each species. 相似文献
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Ash decline induced by Hymenoscyphus pseudoalbidus is an emerging disease that severely affects Fraxinus excelsior stands in Europe. There has been an invasive spread of the disease from east to west in Europe over the last decade. Wood discoloration on infected trunks has been reported, but few data are available on the involvement of H. pseudoalbidus in such symptoms. Transport and trade of ash logs could introduce the pathogen into disease‐free areas and therefore accelerate its dissemination. The aim of this study was to assess the prevalence and severity of H. pseudoalbidus in ash logs in infested areas located in the northeast of France and to clarify the role of secondary pathogens in ash decline. The results showed that prevalence of H. pseudoalbidus on collar lesions was high in the study area. The pathogen was able to produce conidia from infected wood. Thus, export of ash logs could represent a potential risk for spreading the disease. Involvement of Armillaria spp. in the decline process was confirmed, while no Phytophthora‐induced collar lesions were found. Studying both disease prevalence and the age of callus tissues surrounding collar lesions in 60 ash stands enabled the origin of the disease in the study area to be determined. 相似文献
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Marion Durand-Gillmann Maxime Cailleret Thomas Boivin Louis-Michel Nageleisen Hendrik Davi 《Annals of Forest Science》2014,71(6):659-673
? Context
In recent decades, there have been increasing reports of forest decline, especially in Mediterranean forest ecosystems. Decline in tree vitality is usually due to complex interactions between abiotic factors and biotic agents that attack weakened trees.? Aims and methods
Estimating dendrometrical characteristics [basal area increment (BAI), age at DBH from tree ring counting, social status, height, and diameter], tree health status, and a competition index, we investigated the individual vulnerability of a French declining silver fir forest to both mistletoe (Viscum album L. ssp. abietis) and bark beetles (Pityophthorus pityographus Ratz., Pityokteines vorontzovi Jac., and Pityokteines spinidens Reitt.).? Results
BAI was negatively correlated with both mistletoe infection (via mistletoe biomass) and bark beetle attack (number of insects per square meter), but there was evidence of divergence in tree choice between two groups of parasites. Mistletoe preferentially infected isolated and dominant trees that showed higher past growth rates than non-infected ones. Conversely, bark beetles mainly attacked defoliated and preferably declining trees with diameter (DBH) lower than 44.5 cm and slower past growth.? Conclusion
While successive severe drought periods are thought to greatly weaken southern silver fir populations, mistletoe and bark beetles may contribute actively to their decline processes as inciting and contributing factors, respectively. 相似文献
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