Forest and woodland replacement patterns following drought-related mortality

Forest vulnerability to drought is expected to increase under anthropogenic climate change, and drought-induced mortality and community dynamics following drought have major ecological and societal impacts. Here, we show that tree mortality concomitant with drought has led to short-term (mean 5 y, range 1 to 23 y after mortality) vegetation-type conversion in multiple biomes across the world (131 sites). Self-replacement of the dominant tree species was only prevalent in 21% of the examined cases and forests and woodlands shifted to nonwoody vegetation in 10% of them. The ultimate temporal persistence of such changes remains unknown but, given the key role of biological legacies in long-term ecological succession, this emerging picture of postdrought ecological trajectories highlights the potential for major ecosystem reorganization in the coming decades. Community changes were less pronounced under wetter postmortality conditions. Replacement was also influenced by management intensity, and postdrought shrub dominance was higher when pathogens acted as codrivers of tree mortality. Early change in community composition indicates that forests dominated by mesic species generally shifted toward more xeric communities, with replacing tree and shrub species exhibiting drier bioclimatic optima and distribution ranges. However, shifts toward more mesic communities also occurred and multiple pathways of forest replacement were observed for some species. Drought characteristics, species-specific environmental preferences, plant traits, and ecosystem legacies govern postdrought species turnover and subsequent ecological trajectories, with potential far-reaching implications for forest biodiversity and ecosystem services.Additional co-authors: Lucía Galiano, Joseph L. Ganey, Patrick Gonzalez, Anna L. Jacobsen, Jeffrey Michael Kane, Thomas Kitzberger, Juan C. Linares, Suzanne B. Marchetti, George Matusick, Michael Michaelian, Rafael M. Navarro-Cerrillo, Robert Brandon Pratt, Miranda D. Redmond, Andreas Rigling, Francesco Ripullone, Gabriel Sangüesa-Barreda, Yamila Sasal, Sandra Saura-Mas, Maria Laura Suarez, Thomas T. Veblen, Caroline Vincke, and Ben Zeema

Forest and woodland replacement patterns following drought-related mortality

Forest vulnerability to drought is expected to increase under anthropogenic climate change, and drought-induced mortality and community dynamics following drought have major ecological and societal impacts. Here, we show that tree mortality concomitant with drought has led to short-term (mean 5 y, range 1 to 23 y after mortality) vegetation-type conversion in multiple biomes across the world (131 sites). Self-replacement of the dominant tree species was only prevalent in 21% of the examined cases and forests and woodlands shifted to nonwoody vegetation in 10% of them. The ultimate temporal persistence of such changes remains unknown but, given the key role of biological legacies in long-term ecological succession, this emerging picture of postdrought ecological trajectories highlights the potential for major ecosystem reorganization in the coming decades. Community changes were less pronounced under wetter postmortality conditions. Replacement was also influenced by management intensity, and postdrought shrub dominance was higher when pathogens acted as codrivers of tree mortality. Early change in community composition indicates that forests dominated by mesic species generally shifted toward more xeric communities, with replacing tree and shrub species exhibiting drier bioclimatic optima and distribution ranges. However, shifts toward more mesic communities also occurred and multiple pathways of forest replacement were observed for some species. Drought characteristics, species-specific environmental preferences, plant traits, and ecosystem legacies govern post drought species turnover and subsequent ecological trajectories, with potential far-reaching implications for forest biodiversity and ecosystem services.Peer reviewe

Réflexions sur le dépérissement du cèdre de l'Atlas des Aurès (Algérie)

National audienc

Une sylviculture pour le pin d'Alep des Aurès (Algérie)

National audienc

Spatio-Temporal Changes in Aleppo Pine Forest Ecosystems in the Eastern Aures (Algeria)

La présente étude s’inscrit dans le cadre d’une caractérisation de la dynamique spatiotemporelle de l’occupation du sol entre 1987 et 2014 d’une zone forestière située dans l’Aurès oriental (Algérie). La méthode de comparaison diachronique des images satellitaires Landsat a été adoptée. Les résultats ont permis de révéler une évolution régressive de la forêt aurasienne au cours des 27 dernières années (de 1987 à 2014). Cette régression de la couverture végétale est localisée essentiellement au niveau des peuplements de Pin d’Alep qui prédominent dans la région d’étude. La dégradation actuelle serait liée aux changements climatiques récents et amplifiée par l’action anthropique.The present study falls within the framework of a characterization of the spatio-temporal dynamics of land use between 1987 and 2014 of a forest area located in the eastern Aures. The method adopted was diachronic comparison of satellite images. Results revealed regression of the Aures forest during the last 27 years (from 1987 to 2014). This regression of vegetation cover has occurred mainly in the Aleppo pine forest stands that predominate in the study area. The current degradation is thought to be linked to recent climate changes and amplified by human activity

Évolution spatio-temporelle des écosystèmes forestiers à pin D’Alep de L’Aurès oriental en Algérie

CGarah, K., Chafai, C. and Bentouati, A. Évolution spatio-temporelle des écosystèmes forestiers à pin d’Alep de l'Aurès oriental en Algérie. 2016. Lebanese Science Journal, 17(2): 104-116. The present study falls within the framework of a characterization of the spatiotemporal dynamics of land use between 1987 and 2014 of a forest area located in eastern Aures. The method of diachronic comparison of satellite images was adopted. Results revealed profound regressive changes in aurasian forest during the last 27 years (from 1987 to 2014). This regression of vegetation cover is mainly localized in Aleppo pine forest stands which predominates the study area. The current degradation would be related to recent climate changes which have amplified the regression of certain forest ecosystems of the region

Modeling diameter distribution of Aleppo pine (Pinus halepensis Mill.) natural forest in the Aures (Algeria) using the Weibull, Beta and Normal distributions with parameters depending on stand variables

230 temporary plots located in Aleppo pine (Pinus halepensis Mill.) stands in the Aures (Algeria) were used for modeling its structure with three theoretical distributions, i.e., the Weibull; the normal and the Beta one. Parameters of the Weibull distribution were estimated using two methods: the maximum likelihood and the method of moments. Diameter distribution models were obtained by estimation of each distribution parameters and by their prediction using stand variables. Results revealed the efficiency of the Weibull distribution estimated with the method of moments. The parameter estimation method is more accurate compared to parameter recovery method despite the existence of strong correlations between parameters of the theoretical distributions and some population variables such as arithmetic or quadratic mean diameter and dominant height. Plot characteristics revealed the existence of several distribution shapes: symmetrical; dissymmetrical with left asymmetry and reverse I or J-shaped distributions