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Abstract: The aim of this paper is to illustrate how some extreme events could affect forest ecosystems. Forest tree response can be analysed using dendroecological methods, as tree-ring widths are strongly controlled by climatic or biotic events. Years with such events induce similar tree responses and are called pointer years. They can result from extreme climatic events like frost, a heat wave, spring water logging, drought or insect damage… Forest tree species showed contrasting responses to climatic hazards, depending on their sensitivity to water shortage or temperature hardening, as illustrated from our dendrochronological database. For foresters, a drought or a pest disease is an extreme event if visible and durable symptoms are induced (leaf discolouration, leaf loss, perennial organs mortality, tree dieback and mortality). These symptoms here are shown, lagging one or several years behind a climatic or biotic event, from forest decline cases in progress since the 2003 drought or attributed to previous severe droughts or defoliations in France. Tree growth or vitality recovery is illustrated, and the functional interpretation of the long lasting memory of trees is discussed. A coupled approach linking dendrochronology and ecophysiology helps in discussing vulnerability of forest stands, and suggests management advices in order to mitigate extreme drought and cope with selective mortality. [Copyright &y& Elsevier]

Abstract: This paper reports on small mountain glacier variations in the northern Belledonne region (French Alps). Between 1926 and 2006, the evolution is surveyed using remote-sensing techniques. Then, it is correlated with climate data for the same period. In the late 1920s and in 1980, there was a maximum extent of the glaciers. The 1980 surge is due to high precipitations during the late 1970s, a similar trend being punctually observed in 1993. Between 1980 and 2003, the Rocher Blanc glaciers have strongly receded, their total surface being divided by ten. From 1997 onward, the large retreat can be explained by the increase of the mean daily temperature, especially the minimum daily temperature. Moreover, unusually high temperatures have been registered during the summer 2003 heat wave. Small mountain glaciers appear to be more sensitive to climate change than larger ones. Their surfaces change within 6 to 12 months. [Copyright &y& Elsevier]