Search

1. To understand time-­lag dynamics in the response of biodiversity to contem- porary environmental changes (e.g. macroclimate warming and atmospheric pollution), we need to consider former anthropogenic forcing factors such as past land uses and management practices that can have both compounding and confounding effects. This is especially true in European temperate forests, where legacies from past human activities have left strong imprints on today’s understorey plant species composition, generating long-­term lagging effects which can be mistakenly attributed to more recent macro-­environmental changes. 2. By combining the expertise of plant, soil and historical ecologists together with remote sensing scientists, we review the potential of light detection and ranging (LiDAR) to unveil ghosts from the past in terms of former land uses and manage- ment practices. 3. We show that imprints from past land uses and management practices can still be captured today through well-­chosen LiDAR-­derived variables describing, at sub-­decimetre scale, the vertical and horizontal micro-­variations of vegetation and terrain structure hidden below treetops. 4. Synthesis. We encourage plant and soil ecologists to use LiDAR data and to work with historians, archaeologists and remote sensing scientists in order to select meaningful LiDAR-­derived variables to account for time-­lagged biotic responses to long-­term macro-­environmental changes.

Agricultural intensification has altered the provision of natural bioregulation. We assessed the effects of five different crops under non-inversion tillage on the temporal dynamics of carabid assemblages. We evaluated how the taxonomic diversity, the composition, and the diet-based functional structure of communities varied over the spring period.Carabid assemblages were monitored over 4 years (from 2009 to 2012), in a total of 67 fields (each field followed one year) cropped with either winter oilseed rape, winter wheat, sugar beet, spring barley, or spring pea. We assigned a relative diet profile to each species accounting for more than 0.5 % of the total mean abundance-activity: granivorous, phytophagous, and zoophagous.The seasonal changes in species richness, abundance-activity, and evenness had the same dynamic in all crops. Despite differences in species identities between crops, the zoophagous and phytophagous diet profiles showed similar temporal dynamics in all crop types, suggesting a high functional equivalence among species present in cultivated fields. Zoophagous species were progressively replaced by primarily phytophagous species in all crops, while the increase in granivorous species was only observed in oilseed rape.Our results suggest that potential bioregulation do not significantly differ among crop types but vary along the spring season.HighlightsWe monitored carabid communities in five crop types under non-inversion tillageWe observed similar seasonal increases in carabid abundance-activity and species richness in all crops during the spring periodWe observed similar trends in temporal changes in carnivorous and phytophagous diet profiles in all cropsWith seasonal changes, zoophagous species are progressively replaced by more phytophagous speciesCrop type is not the main factor driving temporal changes in diet-based structure of carabid assemblages

The four script files contain the detailed commands used for the bioinformatic processing/filtering of raw sequence data with the OBITools pipeline as well as the post-bioinformatic data cleaning in R (using the ROBITools package). The list of samples tags is also provided.

Forest microclimates contrast strongly with the climate outside forests. To fully understand and better predict how forests' biodiversity and functions relate to climate and climate change, microclimates need to be integrated into ecological research. Despite the potentially broad impact of microclimates on the response of forest ecosystems to global change, our understanding of how microclimates within and below tree canopies modulate biotic responses to global change at the species, community and ecosystem level is still limited. Here, we review how spatial and temporal variation in forest microclimates result from an interplay of forest features, local water balance, topography and landscape composition. We first stress and exemplify the importance of considering forest microclimates to understand variation in biodiversity and ecosystem functions across forest landscapes. Next, we explain how macroclimate warming (of the free atmosphere) can affect microclimates, and vice versa, via interactions with land-use changes across different biomes. Finally, we perform a priority ranking of future research avenues at the interface of microclimate ecology and global change biology, with a specific focus on three key themes: (1) disentangling the abiotic and biotic drivers and feedbacks of forest microclimates; (2) global and regional mapping and predictions of forest microclimates; and (3) the impacts of microclimate on forest biodiversity and ecosystem functioning in the face of climate change. The availability of microclimatic data will significantly increase in the coming decades, characterizing climate variability at unprecedented spatial and temporal scales relevant to biological processes in forests. This will revolutionize our understanding of the dynamics, drivers and implications of forest microclimates on biodiversity and ecological functions, and the impacts of global changes. In order to support the sustainable use of forests and to secure their biodiversity and ecosystem services for future generations, microclimates cannot be ignored.

International audience

The aim of this study was to determine (i) factors which structure populations of dominant carabid beetles over agricultural landscapes and (ii) their spatial and temporal scales of influence, in order to infer population processes involved in species maintain, in response to agroecosystems’ spatiotemporal heterogeneity. Surveys were conducted in three agricultural areas of western France contrasted in their degree of agriculturalintensification, using samplings based on pitfall and emergence traps and realized at several periods in the year. One of the main novelties of this work is to have characterized agroecosystems at different scales, both (i) spatial: the patch of habitat, landscape, region; and (ii) temporal, considering both the current environment and that of the previous year. Moreover, we essentially characterized the influence of habitat dynamics ondistribution and abundance dynamics and dispersal of carabid populations.Our study yielded three major findings. (1) The spatial dynamics of studied carabid species is strongly influenced by habitat types and their temporal instability at different spatial scales. Indeed, we have emphasized the importance of temporal heterogeneity of agricultural landscapes on the spatial dynamics of carabid populations using the agricultural matrix. (2) The dispersal and inter-field movements are an important condition to the success of these species in agricultural landscapes and seem to be mainly induced by crop rotations. (3) Due to large population sizes and an important effective dispersion, spatial and genetic structure of the populations remains low across agricultural landscapes., Dans ce travail de thèse nous avons cherché à déterminer (i) les facteurs structurants des populations des carabiques dominants dans les paysages agricoles et (ii) leur(s) échelle(s) spatiale(s) et temporelle(s) d’influence, afin d’inférer des processus individuels et populationnels impliqués dans le maintien des espèces, en réponse à l’hétérogénéité spatiotemporelle des agroécosystèmes. Notre étude a été réalisée dans trois régions agricoles de l’ouest de la France, contrastées selon leur degré d’intensification agricole, en utilisant des échantillonnages basés sur des pots-pièges et des tentes à émergence et réalisés à plusieurs périodes de l’année.Une des principales originalités de ce travail est d’avoir caractérisé les agroécosystèmes à différentes échelles, tant (i) spatiales : le patch d’habitat, le paysage, la région ; que (ii) temporelles, en considérant à la fois l’environnement présent et celui de l’année précédente. De plus, nous avons essentiellement caractérisé l’influence de la dynamique des habitats sur les dynamiques de distribution et d’abondance et la dispersion despopulations de carabiques Notre étude a abouti à trois résultats majeurs. (1) La dynamique spatiale des espèces de carabiques étudiées est fortement influencée par les types d’habitats et leur instabilité temporelle à différentes échelles spatiales. Nous avons en effet mis en avant l’importance de l’hétérogénéité temporelle des paysages agricoles sur la dynamique spatiale des populations carabiques utilisant la matrice agricole. (2) La dispersion et les mouvements entre parcelles sont une condition importante du succès de ces espèces dans les paysagesagricoles et semblent être principalement induits par les rotations de cultures. (3) Du fait de grandes tailles de populations et d’une dispersion efficace importante, la structuration spatiale et génétique des populations reste faible à l’échelle des paysages agricoles.

International audience

International audience

National audience