Extinction and colonisation of habitat specialists drive plant species replacement along a Mediterranean grassland-forest succession

Bagaria G., Rodà F., Pino J. (2019) Extinction and colonisation of habitat specialists drive plant species replacement along a Mediterranean grassland-forest succession. Journal of Vegetation Science. 30: 331-340.
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Doi: 10.1111/jvs.12722

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Questions: Land-use change causes shifts in species richness, which can be delayed. However, beta-diversity patterns and especially the relative role of species replacement and nestedness in these situations with time-lagged extinctions and colonisations remain unknown. We aim to (a) quantify beta-diversity change, species replacement and nestedness for vascular plants along a grassland–forest succession with time-lagged biodiversity change for more than 50 years; (b) check its consistency between all species, grassland specialists and forest specialists, and (c) identify the role of forest encroachment relative to other drivers. Study site: Prades Mountains, Catalonia (NE Iberian Peninsula). Methods: We sampled 18 sites representing a gradient in past and current grassland area and connectivity, and in forest encroachment intensity, to obtain plant composition of all species, grassland specialists and forest specialists. We quantified overall beta-diversity and its components at each species classification group along the forest encroachment gradient and other drivers. Then, we used general linear models to study (a) the change rate of beta diversity along the forest encroachment gradient and (b) the relative importance of the drivers in explaining beta diversity. Results: Following the forest encroachment gradient, we found an overall noticeable species replacement, while nestedness was the main component for habitat specialists. Landscape differences contributed to explaining most compositional differences (both nestedness and replacement), while soil characteristics and geographic distance had a more restricted contribution. Conclusions: Species replacement due to environmental sorting occurred over the succession, triggered by selective extinctions of grassland specialists and selective colonisations of forest specialists. Nonetheless, historical landscape characteristics, current landscape characteristics and geographic distance modulate plant extinctions and colonisations, suggesting biological inertia, mass effects and habitat isolation, respectively. Partitioning beta-diversity into nestedness and replacement components and exploring the extinction and colonisation patterns of habitat specialist groups might provide relevant insight into the drivers and processes of community shift after land-use change. © 2019 International Association for Vegetation Science

Llegeix més

Sea spray influences water chemical composition of Mediterranean semi-natural springs

Fernández-Martínez M., Margalef O., Sayol F., Asensio D., Bagaria G., Corbera J., Sabater F., Domene X., Preece C. (2019) Sea spray influences water chemical composition of Mediterranean semi-natural springs. Catena. 173: 414-423.
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Doi: 10.1016/j.catena.2018.10.035

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Sea spray aerosol (SSA) is responsible for the large-scale transfer of particles from the sea to the land, leading to significant deposition of a range of ions, predominantly Na+, K+, Mg2+ Ca2+, and Cl−. Up to now, there has been little research into the effects of SSA on spring water chemistry. Therefore, we sampled 303 semi-natural springs across Catalonia (NE Iberian Peninsula) and analysed the concentrations of 20 different ions and elements, and determined the impact of SSA (using distance to the coast as a proxy) as well as climate, lithology and human disturbances. We found that distance to the coast had a clear effect on the water chemical composition of springs, while accounting for potentially confounding factors such as anthropogenic water pollution (nitrate, NO3 −), differences in lithology and annual rainfall. Our results showed that springs located closer to the coast had higher Cl−, SO4 2−, Na+, Mg2+, K+ and Ca2+ concentrations than those of springs located further away. Precipitation was generally negatively correlated with the concentration of almost all elements analysed. The concentration of NO3 − increased with distance to the coast, concurrently with farming activities, located mainly inland in the study area. These results demonstrate that SSA has an important effect on the groundwater of coastal zones, up to a distance of around 70 km from the coastline. This analysis reveals the main natural and human processes that influence spring water chemistry in this Mediterranean region, information that could be helpful in similar regions for ecological studies, water quality policies, and for the improvement of predictions in the current context of global change. © 2018 Elsevier B.V.

Llegeix més

On the influence of water conductivity, pH and climate on bryophyte assemblages in Catalan semi-natural springs

Bes M., Corbera J., Sayol F., Bagaria G., Jover M., Preece C., Viza A., Sabater F., Fernández-Martínez M. (2018) On the influence of water conductivity, pH and climate on bryophyte assemblages in Catalan semi-natural springs. Journal of Bryology. : 1-10.
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Doi: 10.1080/03736687.2018.1446484

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Bryophytes are some of the most sensitive biological indicators of environmental change. Springs have a significant presence of bryophytes and so are ideal habitats for studying their relationship with the environment. We tested whether bryophyte assemblages can be explained with macro-, meso- and micro-ecological variables (i.e. seasonal climate, altitude, water pH and conductivity) sampling bryophytes from 198 semi-natural springs distributed along montane regions in the north-eastern Iberian Peninsula. We tested the influence of environmental variables on bryophyte assemblages in springs using sparse Partial Least Squares. Our results show that variability in bryophyte assemblages is explained by seasonal climate (temperature and precipitation from winter, spring, summer and autumn and temperature and precipitation seasonality), altitude and water conductivity. The results obtained by the present study will be useful for predicting bryophyte diversity in springs using simple and easy to obtain variables such as climate, water pH and conductivity. © British Bryological Society 2018

Llegeix més

Exploring the links between social metabolism and biodiversity distribution across landscape gradients: A regional-scale contribution to the land-sharing versus land-sparing debate

Marull, J., Tello, E., Bagaria, G., Font, X., Cattaneo, C., Pino, J. (2018) Exploring the links between social metabolism and biodiversity distribution across landscape gradients: A regional-scale contribution to the land-sharing versus land-sparing debate. Science of the Total Environment. 619-620: 1272-1285.
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Doi: 10.1016/j.scitotenv.2017.11.196

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Influence of clay licks on the diversity and structure of an Amazonian forest

Molina E., Espelta J.M., Pino J., Bagaria G., Armenteras D. (2018) Influence of clay licks on the diversity and structure of an Amazonian forest. Biotropica. 50: 740-749.
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Doi: 10.1111/btp.12568

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The spatial heterogeneity of resource availability is a major driver of biodiversity patterns. Some environmental conditions and resources are characterized by large-scale patterns of variation within the landscape. Clumped local discontinuities or discrete elements also increase spatial heterogeneity, promoting local ‘biodiversity hot spots’ by modifying habitat characteristics and promoting plant–animal interactions. Clay licks are faunal attractors owing to their role in the nutritional ecology of the user species; nevertheless, the effect of their presence on the surrounding vegetation has been poorly quantified. Here, we use data from 100 × 10 m transects and evaluate the effects of the presence of clay licks on forest diversity and structure at local and landscape scales. In clay lick areas, there was a higher abundance of certain species, which helps to homogenize species composition between localities counteracting the natural distance-decay of compositional similarity between transects without clay lick influence (controls). Compared to control sites, clay lick′s forests had higher palm densities, shorter but more variable individuals in the canopy and understory, a thinner canopy layer, and denser herbaceous and ground level covers. These differences were found along the whole length of transects in both sampled areas types. These results reveal that the presence of discrete elements (i.e., clay licks) may help to explain the compositional and structural heterogeneity of Amazonian forests influencing ecological processes such as seed dispersal and trampling. These considerations may be relevant for other biomes where clay licks are present and give weight to their inclusion in conservation initiatives in tropical forests. © 2018 The Association for Tropical Biology and Conservation

Llegeix més

Contrasting habitat and landscape effects on the fitness of a long-lived grassland plant under forest encroachment: Do they provide evidence for extinction debt?

Bagaria, G., Rodà, F., Clotet, M., Míguez, S., Pino, J. (2017) Contrasting habitat and landscape effects on the fitness of a long-lived grassland plant under forest encroachment: Do they provide evidence for extinction debt?. Journal of Ecology. : 0-0.
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Doi: 10.1111/1365-2745.12860

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Contrasting historical and current land-use correlation with diverse components of current alien plant invasions in Mediterranean habitats

Clotet, M., Basnou, C., Bagaria, G., Pino, J. (2016) Contrasting historical and current land-use correlation with diverse components of current alien plant invasions in Mediterranean habitats. Biological Invasions. 18: 2897-2909.
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Doi: 10.1007/s10530-016-1181-7

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Assessing coexisting plant extinction debt and colonization credit in a grassland–forest change gradient

Bagaria G., Helm A., Rodà F., Pino J. (2015) Assessing coexisting plant extinction debt and colonization credit in a grassland–forest change gradient. Oecologia. 179: 823-834.
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Doi: 10.1007/s00442-015-3377-4

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Changes in species richness along the ecological succession gradient may be strongly determined by coexisting extinction debts of species from the original habitats and colonization credits of those from the replacing habitats. The magnitude of these processes and their causes remain largely unknown. We explored the extinction debt and colonization credit for grassland and forest specialist plants, respectively, and the local and landscape factors associated to the richness of these species groups in a 50-year process of forest encroachment into semi-natural Mediterranean grasslands. A set of sampling plots of persistent grasslands and forests and their transitional habitat (wooded grasslands) was selected within fixed-area sites distributed across the landscape. Our results confirm the extinction debt and suggest colonization credit (according to observed trends and model predictions) in wooded grasslands when compared to persistent forests, despite wooded grasslands and persistent forests having similar tree cover. Grassland connectivity and solar radiation had opposing effects on the richness of both grassland and forest specialists, and it is possible that the availability of seed sources from old forests may have accelerate the payment of colonization credit in the wooded grasslands. These results suggest that extinction debt and colonization credit have driven species turnover during the 50 years of forest encroachment, but at different rates, and that local and landscape factors have opposing effects on these two phenomena. They also highlight the importance of documenting biodiversity time lags following habitat change when they are still in progress in order to timely and adequately manage habitats of high conservation value such as the grasslands studied here. © 2015, Springer-Verlag Berlin Heidelberg.

Llegeix més

Common distribution patterns of marsupials related to physiographical diversity in Venezuela

Ventura J., Bagaria G., Sans-Fuentes M.A., Perez-Hernandez R. (2014) Common distribution patterns of marsupials related to physiographical diversity in Venezuela. PLoS ONE. 9: 0-0.
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Doi: 10.1371/journal.pone.0096714

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The aim of this study is to identify significant biotic regions (groups of areas with similar biotas) and biotic elements (groups of taxa with similar distributions) for the marsupial fauna in a part of northern South America using physiographical areas as Operational Geographical Units (OGUs). We considered Venezuela a good model to elucidate this issue because of its high diversity in landscapes and the relatively vast amount of information available on the geographical distribution of marsupial species. Based on the presence-absence of 33 species in 15 physiographical sub-regions (OGUs) we identified Operational Biogeographical Units (OBUs) and chorotypes using a quantitative analysis that tested statistical significance of the resulting groups. Altitudinal and/or climatic trends in the OBUs and chorotypes were studied using a redundancy analysis. The classification method revealed four OBUs. Strong biotic boundaries separated: i) the xerophytic zone of the Continental coast (OBU I); ii) the sub-regions north of the Orinoco River (OBU III and IV); and those south to the river (OBU II). Eleven chorotypes were identified, four of which included a single species with a restricted geographic distribution. As for the other chorotypes, three main common distribution patterns have been inferred: i) species from the Llanos and/or distributed south of the Orinoco River; ii) species exclusively from the Andes; and iii) species that either occur exclusively north of the Orinoco River or that show a wide distribution throughout Venezuela. Mean altitude, evapotranspiration and precipitation of the driest month, and temperature range allowed us to characterize environmentally most of the OBUs and chorotypes obtained. © 2014 Ventura et al.

Llegeix més

Spatial patterns of land use changes across a mediterranean metropolitan landscape: Implications for biodiversity management

Basnou C., Alvarez E., Bagaria G., Guardiola M., Isern R., Vicente P., Pino J. (2013) Spatial patterns of land use changes across a mediterranean metropolitan landscape: Implications for biodiversity management. Environmental Management. 52: 971-980.
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Doi: 10.1007/s00267-013-0150-5

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Land use and land cover change (LUCC) is an acknowledged cause of the current biodiversity crisis, but the link between LUCC and biodiversity conservation remains largely unknown at the regional scale, especially due to the traditional lack of consistent biodiversity data. We provide a methodological approach for assessing this link through defining a set of major pressures on biodiversity from LUCC and evaluating their extent, distribution, and association with a set of physical factors. The study was performed in the Metropolitan Region of Barcelona (MRB, NE of Spain) between 1956 and 2000. We generated a LUCC map for the time period, which was reclassified into a set of pressures on biodiversity (forestation, deforestation, crop abandonment, and urbanization). We then explored the association of these pressures with a set of physical factors using redundancy analysis (RDA). Pressures encompassed 38.8 % of the MRB area. Urbanization and forestation were the dominating pressures, followed by crop abandonment and deforestation. RDA showed a significant distribution gradient of these pressures in relation to the studied physical factors: while forestation and deforestation are concentrated in remote mountain areas, urbanization mainly occurs in lowlands and especially on the coast, and close to previous urban centers and roads. Unchanged areas are concentrated in rainy and relatively remote mountain areas. Results also showed a dramatic loss of open habitats and of the traditional land use gradient, both featuring Mediterranean landscapes and extremely important for their biodiversity conservation. Implications of these results for biodiversity management are finally discussed. © 2013 Springer Science+Business Media New York.

Llegeix més

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