1. Trait-based approaches applied to community ecology have led to a considerable advance in understanding the effect of environmental filters on species assembly. Although plant traits are known to ...vary both between and within species, little is known about the role of intraspecific trait variability in the non-random assembly mechanisms controlling the coexistence of species, including habitat filtering and niche differentiation. 2. We investigate the role of intraspecific variability in three key functional traits - specific leaf area (SLA), leaf dry matter content (LDMC) and height - in structuring grassland communities distributed along a flooding gradient. We quantified the contribution of intraspecific variability relative to interspecific differences in the trait-gradient relationship, and we used a null model approach to detect patterns of habitat filtering and niche differentiation, with and without intraspecific variability. 3. Community mean SLA and height varied significantly along the flooding gradient and intraspecific variability accounted for 44% and 32%, respectively, of these trait-gradient relationships. LDMC did not vary along the gradient, with and without accounting for intraspecific variability. Our null model approach revealed significant patterns of habitat filtering and niche differentiation for SLA and height, but not for LDMC. More strikingly, considering intraspecific trait variability greatly increased the detection of habitat filtering and was necessary to detect niche differentiation processes. 4. Synthesis. Our study provides evidence for a strong role of intraspecific trait variability in community assembly. Our findings suggest that intraspecific trait variability promotes species coexistence, by enabling species to pass through both abiotic and biotic filters. We argue that community ecology would benefit from more attention to intraspecific variability.
Populations located at the rear-edge of a species' distribution may have disproportionate ecological and evolutionary importance for biodiversity conservation in a changing global environment. Yet ...genetic studies of such populations remain rare. This study investigates the evolutionary history of North-African low latitude marginal populations of Alnus glutinosa Gaertn., a European tree species that plays a significant ecological role as a keystone of riparian ecosystems. We genotyped 551 adults from 19 populations located across North Africa at 12 microsatellite loci and applied a coalescent-based simulation approach to reconstruct the demographic and evolutionary history of these populations. Surprisingly, Moroccan trees were tetraploids demonstrating a strong distinctiveness of these populations within a species otherwise known as diploid. Best-fitting models of demographic reconstruction revealed the relict nature of Moroccan populations that were found to have withstood past climate change events and to be much older than Algerian and Tunisian populations. This study highlights the complex demographic history that can be encountered in rear-edge distribution margins that here consist of both old stable climate relict and more recent populations, distinctively diverse genetically both quantitatively and qualitatively. We emphasize the high evolutionary and conservation value of marginal rear-edge populations of a keystone riparian species in the context of on-going climate change in the Mediterranean region.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In the Congo Basin, paleoenvironmental data are scarce, due to the lack of natural lakes. Using marshes sedimentary deposits as alternative archives requires the calibration of modern pollen ...assemblages, which are totally absent for these type of deposits. The aim of this study is to understand and qualify how well surface marsh sediment pollen assemblages reflect the contemporary vegetation. We compare pollen assemblages at the surface of 23 sedge marshes disseminated in an enclave of savanna in the Gabonese forest and vegetation surveys along transects from sampling areas. Very high diversity of forest pollen taxa is recorded, with a gradient of diversity from most open environments to those where the forest is closer, however savanna taxa remains low. The surface samples surprisingly reveal general weak percentages of Poaceae pollen grains that never exceed 25%. The low proportion of Poaceae is consistent with the deposition mode of pollen in these specific sites but challenges the common interpretation of a straightforward relationship between this percentage and savanna/forest balance.
•First modern pollen rain analysis from sedge marshes in an enclave of savanna in the Central African tropical moist forest•Far weaker than expected percentages of Poaceae pollen found on the surface of marshes•Forest tree pollen grains predominate assemblages even in marsh surrounded by savanna
Evidence from an international survey in the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is reducing plant species richness in acid grasslands. Across the ...deposition gradient in this region (2–44 kg N ha
−1 yr
−1) species richness showed a curvilinear response, with greatest reductions in species richness when deposition increased from low levels. This has important implications for conservation policies, suggesting that to protect the most sensitive grasslands resources should be focussed where deposition is currently low. Soil pH is also an important driver of species richness indicating that the acidifying effect of nitrogen deposition may be contributing to species richness reductions. The results of this survey suggest that the impacts of nitrogen deposition can be observed over a large geographical range.
Atmospheric nitrogen deposition is reducing biodiversity in grasslands across Europe.
These data are coming from the derogation requests for the destruction of protected species in the context of construction or development work in France. These derogation requests include, among ...other things, the contents of an environmental impact assessment and the costs of the measures suggested to reduce the impact on the environment. In the article connected to this dataset, we studied the quality of the plant translocation protocols proposed in 95 derogation files (see Julien et al., 2022). We additionally collected during the reading of the files data that we make available here about the costs of (i) the total project, (ii) the mitigation hierarchy and (iii) the plant translocation operations and monitoring. These data complement our aforementioned paper by documenting how much translocations cost and in what proportion of the other costs reported in the projects we evaluated for quality. These data can be helpful for environmental stakeholders but also to further studies to determine the extent to which the environment is considered in land planning.
Impact of nitrogen deposition at the species level Payne, Richard J.; Dise, Nancy B.; Stevens, Carly J. ...
Proceedings of the National Academy of Sciences - PNAS,
01/2013, Letnik:
110, Številka:
3
Journal Article
Recenzirano
Odprti dostop
In Europe and, increasingly, the rest of the world, the key policy tool for the control of air pollution is the critical load, a level of pollution below which there are no known significant harmful ...effects on the environment. Critical loads are used to map sensitive regions and habitats, permit individual polluting activities, and frame international negotiations on transboundary air pollution. Despite their fundamental importance in environmental science and policy, there has been no systematic attempt to verify a critical load with field survey data. Here, we use a large dataset of European grasslands along a gradient of nitrogen (N) deposition to show statistically significant declines in the abundance of species from the lowest level of N deposition at which it is possible to identify a change. Approximately 60% of species change points occur at or below the range of the currently established critical load. If this result is found more widely, the underlying principle of no harm in pollution policy may need to be modified to one of informed decisions on how much harm is acceptable. Our results highlight the importance of protecting currently unpolluted areas from new pollution sources, because we cannot rule out ecological impacts from even relatively small increases in reactive N deposition.
Climatic changes in southern Europe during the Holocene are characterized by a strong spatial and temporal heterogeneity whose patterns are still poorly understood, notably the presence or not of a ...Holocene thermal maximum (HTM; 10 000–6000 cal BP). The climatic patterns also differ according to the proxies used (e.g. pollen, chironomid) and the latitude of the record. Here, a multi-proxy approach combining pollen and lipid biomarkers (branched glycerol dialkyl glycerol tetraethers, brGDGTs) is applied to the Canroute sedimentological sequence (Massif Central, France) to reconstruct the climatic variation over the last 15 000 years in southern Europe. This area is poorly documented in terms of vegetation and climate change. To provide reliable climate reconstructions, we have (1) performed a multi-method approach applied to pollen (modern analogue technique, MAT; weighted averaging partial least squares regression, WA-PLS; boosted regression trees, BRT; and random forest, RF) and molecular biomarkers brGDGTs (five calibrations) and (2) investigated the role of modern databases and calibrations in climate reconstructions. Three different databases were tested for pollen data: one global database based on a Eurasian pollen database and two regional databases corresponding to Mediterranean–Temperate Europe and Temperate Europe–Scandinavian databases respectively. Five global calibrations were tested for lipid biomarkers including four for soil and one for peat. Results show that the use of different modern databases highlights the importance of considering environmental and ecological constraints when using transfer functions on pollen sequences. Pollen- and brGDGT-inferred climate trends are consistent, notably for the Late Glacial and the Early and Late Holocene. However, the reconstructions notably differ concerning the presence of a Holocene thermal maximum with the MAT pollen-based method, but no difference is apparent with the BRT pollen method nor brGDGT. The temperature reconstructions estimated from the two independent pollen and lipid proxies are then compared to regional climate signals (chironomids, pollen, molecular biomarkers) to better understand global regional climatic patterns in southern Europe. Altogether, our results from the Canroute sequence and those already available in southern Europe reveal that for the Late Glacial and Early Holocene, the regional climate trends are consistent between sites and proxies, supporting the reliability of their reconstructions despite some discrepancies. During the Holocene, the temperature signal of Canroute does not indicate the clear presence of a pronounced HTM, but rather stable temperatures.
We provide a quantitative description of the French national herbarium vascular plants collection dataset. Held at the Muséum national d'histoire naturelle, Paris, it currently comprises records for ...5,400,000 specimens, representing 90% of the estimated total of specimens. Ninety nine percent of the specimen entries are linked to one or more images and 16% have field-collecting information available. This major botanical collection represents the results of over three centuries of exploration and study. The sources of the collection are global, with a strong representation for France, including overseas territories, and former French colonies. The compilation of this dataset was made possible through numerous national and international projects, the most important of which was linked to the renovation of the herbarium building. The vascular plant collection is actively expanding today, hence the continuous growth exhibited by the dataset, which can be fully accessed through the GBIF portal or the MNHN database portal (available at: https://science.mnhn.fr/institution/mnhn/collection/p/item/search/form). This dataset is a major source of data for systematics, global plants macroecological studies or conservation assessments.
We compiled a list of 148 exotic species in French inland freshwaters, comprising 36 plant species and 112 animals, including 50 invertebrates, 7 amphibians, 1 reptile, 25 fish, 22 birds and 7 ...mammals. Spatial distribution maps and cumulative analyses for most species indicate that exotic plants are distributed more along the west coast of France and, to a lesser extent, the Rhone basin, whereas exotic animals are clearly clumped in the north-east (Rhine Basin). The rate of introductions has increased exponentially over time. The most recent introductions (since 1992) have occurred in the Rhine Basin, from where they have then spread. Twenty-five species on our list are among the ‘100 worst invasive species of Europe’ (DAISIE) and 11 among the worst in the world (IUCN), with six species included on both lists. The potential cumulative impact of exotic species tends to be heterogeneous across France, though the north-east appears to be more disturbed, especially by animal species. Additional research is needed on criteria for prioritising intervention measures that will help stakeholders make objective choices in the management of exotic species in aquatic ecosystems.
Unlike southern Spain, northern Morocco has been little investigated for palaeoecological purposes. Consequently, the origin and history of the Rifan vegetation is largely unknown, as well as the ...past role of human activities. A review of the Plio-Pleistocene fossil data available from North Africa clearly reveals the ancient origin of much of the present-day flora and vegetation structures of the region. A well-dated pollen record covering the last 5,000 years, obtained from a fen, is compared to previous regional pollen data in order to understand the late-Holocene vegetation dynamics and the influence of anthropogenic disturbances. Modern pollen spectra have allowed the calibration of pollen diversity and evenness as indicators of tree-cover density. The results obtained show the long-term persistence of regional forests until the onset of Arab Sharifian dynasties in the 16th century, with a surprising lack of human impact during the late Neolithic, and little impact during Roman colonisation. The increasing density of deciduous forests recorded from 3,800 to 1,900 cal BP, concomitant with the expansion of cedar in the Middle Atlas, could reveal the onset of widespread cooler and moister climatic conditions. The weak and late human impact in the Rifan mountains explains, at least in part, their high diversity and the conservation of their forest ecosystems. Anthropogenic activities however have led to severe modification of the understorey structure of these forests during the four last centuries, and to the worrying on-going deforestation that presently threatens the survival of this invaluable biological heritage.
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