• Energy Research
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SignificanceForests are experiencing growing risks of drought-induced mortality in a warming world. Yet, ecosystem dynamics following drought mortality remain unknown, representing a major limitation to our understanding of the ecological consequences of climate change. We provide an emerging picture of postdrought ecological trajectories based on field indicators of forest dynamics. Replacement patterns following mortality indicate limited short-term persistence of predrought dominant tree species, highlighting the potential for major ecosystem reorganization in the coming decades. The great variability of the observed dynamics within and among species reinforces the primary influence of drought characteristics and ecosystem legacies, modulated by land use, management, and past disturbances, on ongoing drought-related species turnover and their potential implications for future forest biodiversity and ecosystem services.

Using long-term measurements in a mature beech (Fagus sylvatica L.)-dominated forest located in east Belgium, this paper showed that spring and autumn temperature increases during the last two decades led to an earlier end and a shortening of the growing season. These phenological shifts impact negatively but not significantly the forest annual net ecosystem productivity. The mechanisms controlling temperate forest phenology are not fully understood nor are the impacts of climate change and the consequences for forest productivity. The aim of this paper is to contribute to the understanding of how temperate forest phenology and net ecosystem productivity (NEP) interplay and respond to temperature and its evolution. Indicators of leaf phenology and productivity dynamics at the start and the end of the growing season, as well as combinations of these indicators (length of the growing season), were derived from a long-term (1997–2014) dataset of eddy covariance and light transmission measurements taken over a mature beech-dominated temperate forest. The start and the end of the growing season were correlated to spring (and autumn, for the end) temperatures. Despite no trends in annual average temperatures being detected during the observation period, April and November temperatures significantly increased. As a result, an earlier but slower start and an earlier end, inducing a shorter length of the growing season, were observed over the studied period. The first shift positively impacts the mixed forest NEP but is mainly related to the presence of conifers in the subplot. The earlier end of the growing season, more related to beech phenology, negatively impacts the forest NEP. Overall, these two effects partially compensate each other, leading to a non-significant impact on NEP. Increasing temperatures over the 18-year studied period shortened the growing season length, without affecting significantly the mixed forest NEP. However, as beeches are only affected by the earlier end of the growing season, this suggests a phenologically driven beech productivity reduction in the forest.