Relations entre diversité des habitats forestiers et communautés de chiroptères à différentes échelles spatiales en Europe : implications pour leur conservation et le maintien de leur fonction de prédation

Insectivorous bats are increasingly recognized as potential regulators of pest insect populations.They also represent the group of European mammals with the most unfavorable conservation status. Forests are key habitats for many bat species but are currently under threat from climate change and fragmentation. It is therefore urgent to better understand the relationships between the bats, their prey and their habitats in forests. Our main objective was to quantify the effects, at multiple spatial scales, of the main attributes of forest habitats on the activity, species richness, functional diversity and composition of European bat communities. They were studied using manipulative experiments in Aquitaine plantation forests and automatic recordings in the network of exploratory plots set up in six European countries by the FunDivEurope project. From the plot to the continent scale, increasing tree diversity, amount of broad leaved trees and dead wood, had positive effects on bat communities through an increase in prey and roost resources. However these effects were not stationary, being stronger at higher latitudes, probably due to lower habitat carrying capacity in relation to harsher climatic conditions. In addition we experimentally demonstrated that the numerical and functional responses of bats to prey density could result in effective regulation of pine processionary moth populations. Forest management strategies aim at enhancing key habitat structures, are eventually proposed in order to improve the conservation of bats and to increase the service of pest regulation they can provide.Les chiroptères sont reconnus comme de potentiels régulateurs des populations d’insectes. Ce sont aussi les mammifères européens pour lesquels les enjeux de conservation sont les plus importants. Ils trouvent dans les forêts des habitats favorables qui sont cependant menacés par les changements climatiques et la fragmentation. Il convient donc de mieux comprendre lesrelations entre les communautés de chiroptères, leurs habitats et leurs proies en forêt. L'objectif de cette thèse est de quantifier les effets, à différentes échelles spatiales, desprincipales composantes de l’habitat forestier sur l’activité, la richesse spécifique, la diversité fonctionnelle et la composition des communautés de chiroptères européens. Les résultats reposent sur des données collectées grâce à des protocoles expérimentaux en Aquitaine et dans les six pays du réseau de placettes forestières organisé par le projet FunDivEurope. De la parcelle au continent, l'accroissement de la diversité des essences forestières, de la proportion de feuillus et du bois mort, en augmentant les ressources en proies et en gîtes, ont des effets positifs sur les communautés de chiroptères. Ces effets, non stationnaires, se renforcent vers le nord avec la rigueur du climat. Nous confirmons également que les chiroptères forestiers, par leur réponse numérique et fonctionnelle aux densités de proie, peuvent limiter la démographie d’un insecte défoliateur. Des mesures de gestion, visant le renforcement des structures-clés des habitats forestiers, sont proposées pour favoriser la conservation des communautés de chiroptères et leur capacité de régulation des insectes ravageurs

Biotic predictors complement models of bat and bird responses to climate and tree diversity in European forests

Bats and birds are key providers of ecosystem services in forests. How climate and habitat jointly shape their communities is well studied, but whether biotic predictors from other trophic levels may improve bird and bat diversity models is less known, especially across large bioclimatic gradients. Here, we achieved multi-taxa surveys in 209 mature forests replicated in six European countries from Spain to Finland, to investigate the importance of biotic predictors (i.e., the abundance or activity of defoliating insects, spiders, earthworms and wild ungulates) for bat and bird taxonomic and functional diversity. We found that 9 out of 12 bird and bat diversity metrics were best explained when biotic factors were added to models including climate and habitat variables, with a mean gain in explained variance of 38% for birds and 15% for bats. Tree functional diversity was the most important habitat predictor for birds, while bats responded more to understorey structure. The best biotic predictors for birds were spider abundance and defoliating insect activity, while only bat functional evenness responded positively to insect activity. Accounting for potential biotic interactions between bats, birds and other taxa of lower trophic levels will help to understand how environmental changes along large biogeographical gradients affect higher-level predator diversity in forest ecosystems

Jack-of-all-trades effects drive biodiversity-ecosystem multifunctionality relationships in European forests.

There is considerable evidence that biodiversity promotes multiple ecosystem functions (multifunctionality), thus ensuring the delivery of ecosystem services important for human well-being. However, the mechanisms underlying this relationship are poorly understood, especially in natural ecosystems. We develop a novel approach to partition biodiversity effects on multifunctionality into three mechanisms and apply this to European forest data. We show that throughout Europe, tree diversity is positively related with multifunctionality when moderate levels of functioning are required, but negatively when very high function levels are desired. For two well-known mechanisms, 'complementarity' and 'selection', we detect only minor effects on multifunctionality. Instead a third, so far overlooked mechanism, the 'jack-of-all-trades' effect, caused by the averaging of individual species effects on function, drives observed patterns. Simulations demonstrate that jack-of-all-trades effects occur whenever species effects on different functions are not perfectly correlated, meaning they may contribute to diversity-multifunctionality relationships in many of the world's ecosystems.The research leading to these results received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 265171.This is the final version of the article. It first appeared from Nature Publishing Group via http://dx.doi.org/10.1038/ncomms1110

Biotic homogenization can decrease landscape-scale forest multifunctionality.

Many experiments have shown that local biodiversity loss impairs the ability of ecosystems to maintain multiple ecosystem functions at high levels (multifunctionality). In contrast, the role of biodiversity in driving ecosystem multifunctionality at landscape scales remains unresolved. We used a comprehensive pan-European dataset, including 16 ecosystem functions measured in 209 forest plots across six European countries, and performed simulations to investigate how local plot-scale richness of tree species (α-diversity) and their turnover between plots (β-diversity) are related to landscape-scale multifunctionality. After accounting for variation in environmental conditions, we found that relationships between α-diversity and landscape-scale multifunctionality varied from positive to negative depending on the multifunctionality metric used. In contrast, when significant, relationships between β-diversity and landscape-scale multifunctionality were always positive, because a high spatial turnover in species composition was closely related to a high spatial turnover in functions that were supported at high levels. Our findings have major implications for forest management and indicate that biotic homogenization can have previously unrecognized and negative consequences for large-scale ecosystem multifunctionality.We thank the Hainich National Park administration as well as Felix Berthold and Carsten Beinhoff for support of this study and Gerald Kaendler and the Johann Heinrich von Thünen-Institut for providing access to the German National Forest Inventory data. The research leading to these results received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under Grant Agreement 265171.This is the final version of the article. It first appeared from the National Academy of Sciences via https://doi.org//10.1073/pnas.151790311

Relationships between forest habitat diversity and bat communities at different spatial scales in Europe

Les chiroptères sont reconnus comme de potentiels régulateurs des populations d’insectes. Ce sont aussi les mammifères européens pour lesquels les enjeux de conservation sont les plus importants. Ils trouvent dans les forêts des habitats favorables qui sont cependant menacés par les changements climatiques et la fragmentation. Il convient donc de mieux comprendre lesrelations entre les communautés de chiroptères, leurs habitats et leurs proies en forêt. L'objectif de cette thèse est de quantifier les effets, à différentes échelles spatiales, desprincipales composantes de l’habitat forestier sur l’activité, la richesse spécifique, la diversité fonctionnelle et la composition des communautés de chiroptères européens. Les résultats reposent sur des données collectées grâce à des protocoles expérimentaux en Aquitaine et dans les six pays du réseau de placettes forestières organisé par le projet FunDivEurope. De la parcelle au continent, l'accroissement de la diversité des essences forestières, de la proportion de feuillus et du bois mort, en augmentant les ressources en proies et en gîtes, ont des effets positifs sur les communautés de chiroptères. Ces effets, non stationnaires, se renforcent vers le nord avec la rigueur du climat. Nous confirmons également que les chiroptères forestiers, par leur réponse numérique et fonctionnelle aux densités de proie, peuvent limiter la démographie d’un insecte défoliateur. Des mesures de gestion, visant le renforcement des structures-clés des habitats forestiers, sont proposées pour favoriser la conservation des communautés de chiroptères et leur capacité de régulation des insectes ravageurs.Insectivorous bats are increasingly recognized as potential regulators of pest insect populations.They also represent the group of European mammals with the most unfavorable conservation status. Forests are key habitats for many bat species but are currently under threat from climate change and fragmentation. It is therefore urgent to better understand the relationships between the bats, their prey and their habitats in forests. Our main objective was to quantify the effects, at multiple spatial scales, of the main attributes of forest habitats on the activity, species richness, functional diversity and composition of European bat communities. They were studied using manipulative experiments in Aquitaine plantation forests and automatic recordings in the network of exploratory plots set up in six European countries by the FunDivEurope project. From the plot to the continent scale, increasing tree diversity, amount of broad leaved trees and dead wood, had positive effects on bat communities through an increase in prey and roost resources. However these effects were not stationary, being stronger at higher latitudes, probably due to lower habitat carrying capacity in relation to harsher climatic conditions. In addition we experimentally demonstrated that the numerical and functional responses of bats to prey density could result in effective regulation of pine processionary moth populations. Forest management strategies aim at enhancing key habitat structures, are eventually proposed in order to improve the conservation of bats and to increase the service of pest regulation they can provide

Relationships between forest habitat diversity and bat communities at different spatial scales in Europe

Les chiroptères sont reconnus comme de potentiels régulateurs des populations d’insectes. Ce sont aussi les mammifères européens pour lesquels les enjeux de conservation sont les plus importants. Ils trouvent dans les forêts des habitats favorables qui sont cependant menacés par les changements climatiques et la fragmentation. Il convient donc de mieux comprendre lesrelations entre les communautés de chiroptères, leurs habitats et leurs proies en forêt. L'objectif de cette thèse est de quantifier les effets, à différentes échelles spatiales, desprincipales composantes de l’habitat forestier sur l’activité, la richesse spécifique, la diversité fonctionnelle et la composition des communautés de chiroptères européens. Les résultats reposent sur des données collectées grâce à des protocoles expérimentaux en Aquitaine et dans les six pays du réseau de placettes forestières organisé par le projet FunDivEurope. De la parcelle au continent, l'accroissement de la diversité des essences forestières, de la proportion de feuillus et du bois mort, en augmentant les ressources en proies et en gîtes, ont des effets positifs sur les communautés de chiroptères. Ces effets, non stationnaires, se renforcent vers le nord avec la rigueur du climat. Nous confirmons également que les chiroptères forestiers, par leur réponse numérique et fonctionnelle aux densités de proie, peuvent limiter la démographie d’un insecte défoliateur. Des mesures de gestion, visant le renforcement des structures-clés des habitats forestiers, sont proposées pour favoriser la conservation des communautés de chiroptères et leur capacité de régulation des insectes ravageurs.Insectivorous bats are increasingly recognized as potential regulators of pest insect populations.They also represent the group of European mammals with the most unfavorable conservation status. Forests are key habitats for many bat species but are currently under threat from climate change and fragmentation. It is therefore urgent to better understand the relationships between the bats, their prey and their habitats in forests. Our main objective was to quantify the effects, at multiple spatial scales, of the main attributes of forest habitats on the activity, species richness, functional diversity and composition of European bat communities. They were studied using manipulative experiments in Aquitaine plantation forests and automatic recordings in the network of exploratory plots set up in six European countries by the FunDivEurope project. From the plot to the continent scale, increasing tree diversity, amount of broad leaved trees and dead wood, had positive effects on bat communities through an increase in prey and roost resources. However these effects were not stationary, being stronger at higher latitudes, probably due to lower habitat carrying capacity in relation to harsher climatic conditions. In addition we experimentally demonstrated that the numerical and functional responses of bats to prey density could result in effective regulation of pine processionary moth populations. Forest management strategies aim at enhancing key habitat structures, are eventually proposed in order to improve the conservation of bats and to increase the service of pest regulation they can provide

Relationships between forest habitat diversity and bat communities at different spatial scales in Europe

Les chiroptères sont reconnus comme de potentiels régulateurs des populations d’insectes. Ce sont aussi les mammifères européens pour lesquels les enjeux de conservation sont les plus importants. Ils trouvent dans les forêts des habitats favorables qui sont cependant menacés par les changements climatiques et la fragmentation. Il convient donc de mieux comprendre lesrelations entre les communautés de chiroptères, leurs habitats et leurs proies en forêt. L'objectif de cette thèse est de quantifier les effets, à différentes échelles spatiales, desprincipales composantes de l’habitat forestier sur l’activité, la richesse spécifique, la diversité fonctionnelle et la composition des communautés de chiroptères européens. Les résultats reposent sur des données collectées grâce à des protocoles expérimentaux en Aquitaine et dans les six pays du réseau de placettes forestières organisé par le projet FunDivEurope. De la parcelle au continent, l'accroissement de la diversité des essences forestières, de la proportion de feuillus et du bois mort, en augmentant les ressources en proies et en gîtes, ont des effets positifs sur les communautés de chiroptères. Ces effets, non stationnaires, se renforcent vers le nord avec la rigueur du climat. Nous confirmons également que les chiroptères forestiers, par leur réponse numérique et fonctionnelle aux densités de proie, peuvent limiter la démographie d’un insecte défoliateur. Des mesures de gestion, visant le renforcement des structures-clés des habitats forestiers, sont proposées pour favoriser la conservation des communautés de chiroptères et leur capacité de régulation des insectes ravageurs.Insectivorous bats are increasingly recognized as potential regulators of pest insect populations.They also represent the group of European mammals with the most unfavorable conservation status. Forests are key habitats for many bat species but are currently under threat from climate change and fragmentation. It is therefore urgent to better understand the relationships between the bats, their prey and their habitats in forests. Our main objective was to quantify the effects, at multiple spatial scales, of the main attributes of forest habitats on the activity, species richness, functional diversity and composition of European bat communities. They were studied using manipulative experiments in Aquitaine plantation forests and automatic recordings in the network of exploratory plots set up in six European countries by the FunDivEurope project. From the plot to the continent scale, increasing tree diversity, amount of broad leaved trees and dead wood, had positive effects on bat communities through an increase in prey and roost resources. However these effects were not stationary, being stronger at higher latitudes, probably due to lower habitat carrying capacity in relation to harsher climatic conditions. In addition we experimentally demonstrated that the numerical and functional responses of bats to prey density could result in effective regulation of pine processionary moth populations. Forest management strategies aim at enhancing key habitat structures, are eventually proposed in order to improve the conservation of bats and to increase the service of pest regulation they can provide

Relationships between forest habitat diversity and bat communities at different spatial scales in Europe

Les chiroptères sont reconnus comme de potentiels régulateurs des populations d’insectes. Ce sont aussi les mammifères européens pour lesquels les enjeux de conservation sont les plus importants. Ils trouvent dans les forêts des habitats favorables qui sont cependant menacés par les changements climatiques et la fragmentation. Il convient donc de mieux comprendre lesrelations entre les communautés de chiroptères, leurs habitats et leurs proies en forêt. L'objectif de cette thèse est de quantifier les effets, à différentes échelles spatiales, desprincipales composantes de l’habitat forestier sur l’activité, la richesse spécifique, la diversité fonctionnelle et la composition des communautés de chiroptères européens. Les résultats reposent sur des données collectées grâce à des protocoles expérimentaux en Aquitaine et dans les six pays du réseau de placettes forestières organisé par le projet FunDivEurope. De la parcelle au continent, l'accroissement de la diversité des essences forestières, de la proportion de feuillus et du bois mort, en augmentant les ressources en proies et en gîtes, ont des effets positifs sur les communautés de chiroptères. Ces effets, non stationnaires, se renforcent vers le nord avec la rigueur du climat. Nous confirmons également que les chiroptères forestiers, par leur réponse numérique et fonctionnelle aux densités de proie, peuvent limiter la démographie d’un insecte défoliateur. Des mesures de gestion, visant le renforcement des structures-clés des habitats forestiers, sont proposées pour favoriser la conservation des communautés de chiroptères et leur capacité de régulation des insectes ravageurs.Insectivorous bats are increasingly recognized as potential regulators of pest insect populations.They also represent the group of European mammals with the most unfavorable conservation status. Forests are key habitats for many bat species but are currently under threat from climate change and fragmentation. It is therefore urgent to better understand the relationships between the bats, their prey and their habitats in forests. Our main objective was to quantify the effects, at multiple spatial scales, of the main attributes of forest habitats on the activity, species richness, functional diversity and composition of European bat communities. They were studied using manipulative experiments in Aquitaine plantation forests and automatic recordings in the network of exploratory plots set up in six European countries by the FunDivEurope project. From the plot to the continent scale, increasing tree diversity, amount of broad leaved trees and dead wood, had positive effects on bat communities through an increase in prey and roost resources. However these effects were not stationary, being stronger at higher latitudes, probably due to lower habitat carrying capacity in relation to harsher climatic conditions. In addition we experimentally demonstrated that the numerical and functional responses of bats to prey density could result in effective regulation of pine processionary moth populations. Forest management strategies aim at enhancing key habitat structures, are eventually proposed in order to improve the conservation of bats and to increase the service of pest regulation they can provide