History matters: Previous land use changes determine post-fire vegetation recovery in forested Mediterranean landscapes

Puerta-Piñero C., Espelta J.M., Sánchez-Humanes B., Rodrigo A., Coll L., Brotons L. (2012) History matters: Previous land use changes determine post-fire vegetation recovery in forested Mediterranean landscapes. Forest Ecology and Management. 279: 121-127.
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Doi: 10.1016/j.foreco.2012.05.020

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Land use changes and shifts in disturbance regimes (e.g. wildfires) are recognized worldwide as two of the major drivers of the current global change in terrestrial ecosystems. We expect that, in areas with large-scale land use changes, legacies from previous land uses persist and affect current ecosystem responses to climate-associated disturbances like fire. This study analyses whether post-fire vegetation dynamics may differ according to specific historical land use histories in a Mediterranean forest landscape of about 60,000. ha that was burnt by extensive fires. For that, we assessed land use history of the whole area through the second half of the XXth century, and evaluated the post-fire regeneration success in terms of: (i) forest cover and (ii) tree species composition (biotic-dispersed, resprouter species, Quercus spp. vs. wind-dispersed species with or without fire-resistant seed bank, Pinus spp.). Results showed that stable forest areas exhibited a higher post-fire recovery than younger forests. Furthermore, the longer since crop abandonment translates into a faster post-fire recovery. Results highlight that to anticipate the impacts of disturbances on ecosystems, historical land trajectories should be taken into account. © 2012 Elsevier Ltd.

Llegeix més

The effect of postfire salvage logging on bird communities in Mediterranean pine forests: The benefits for declining species

Rost J., Clavero M., Brotons L., Pons P. (2012) The effect of postfire salvage logging on bird communities in Mediterranean pine forests: The benefits for declining species. Journal of Applied Ecology. 49: 644-651.
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Doi: 10.1111/j.1365-2664.2012.02127.x

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1.Postfire salvage logging is the most commonly applied forestry practice in burned forests world-wide, mainly for economic reasons. However, it strongly affects bird communities and is generally considered to be detrimental for bird conservation. In Europe, many open-habitat species are currently declining owing to land use changes. Wildfires, which are common disturbances in the Mediterranean Basin, can create suitable habitat for these species but the effect of postfire salvage logging on bird communities is unknown. 2.We surveyed breeding birds in two burned secondary pine forests from the western Mediterranean Basin and analysed the effect of salvage logging and vegetation regeneration as determinants of individual species and community parameters. We used a pseudoexperimental before-after-control-impact approach to study the changes in the bird community during the first three springs after fire. 3.Most bird species were affected by salvage logging (measured by snag density), a relationship that was positive for forest birds and negative for open-habitat species. Species linked to shrub and edge habitats were positively affected by vegetation regrowth. Bird communities in logged areas held more species of conservation concern than those in unlogged areas. Species richness and overall density tended to decrease from the first to the second year after fire and to increase from the second to the third. 4.Salvage logging benefits a number of open-habitat species, although its effect on bird conservation depends strongly on the specific threats that birds face in each region or ecosystem. 5.Synthesis and applications. In the Mediterranean Basin, some postfire salvage logging of pine forests can be compatible with bird conservation. We recommend that managers retain some standing dead trees during logging operations and that logged forest is interspersed with unlogged stands. This will provide suitable habitat for the widest range of species. © 2012 The Authors. Journal of Applied Ecology © 2012 British Ecological Society.

Llegeix més

Mapping from heterogeneous biodiversity monitoring data sources

Sardà-Palomera F., Brotons L., Villero D., Sierdsema H., Newson S.E., Jiguet F. (2012) Mapping from heterogeneous biodiversity monitoring data sources. Biodiversity and Conservation. 21: 2927-2948.
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Doi: 10.1007/s10531-012-0347-6

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Field monitoring can vary from simple volunteer opportunistic observations to professional standardised monitoring surveys, leading to a trade-off between data quality and data collection costs. Such variability in data quality may result in biased predictions obtained from species distribution models (SDMs). We aimed to identify the limitations of different monitoring data sources for developing species distribution maps and to evaluate their potential for spatial data integration in a conservation context. Using Maxent, SDMs were generated from three different bird data sources in Catalonia, which differ in the degree of standardisation and available sample size. In addition, an alternative approach for modelling species distributions was applied, which combined the three data sources at a large spatial scale, but then downscaling to the required resolution. Finally, SDM predictions were used to identify species richness and high quality areas (hotspots) from different treatments. Models were evaluated by using high quality Atlas information. We show that both sample size and survey methodology used to collect the data are important in delivering robust information on species distributions. Models based on standardized monitoring provided higher accuracy with a lower sample size, especially when modelling common species. Accuracy of models from opportunistic observations substantially increased when modelling uncommon species, giving similar accuracy to a more standardized survey. Although downscaling data through a SDM approach appears to be a useful tool in cases of data shortage or low data quality and heterogeneity, it will tend to overestimate species distributions. In order to identify distributions of species, data with different quality may be appropriate. However, to identify biodiversity hotspots high quality information is needed. © 2012 Springer Science+Business Media B.V.

Llegeix més

Modelling seasonal changes in the distribution of Common Quail Coturnix coturnix in farmland landscapes using remote sensing

Sardà-Palomera F., Puigcerver M., Brotons L., Rodríguez-Teijeiro J.D. (2012) Modelling seasonal changes in the distribution of Common Quail Coturnix coturnix in farmland landscapes using remote sensing. Ibis. 154: 703-713.
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Doi: 10.1111/j.1474-919X.2012.01254.x

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Species' distribution models are widely used in landscape ecology but usually lack explicit information about species' responses to ecosystem dynamics, leading to uncertainty when applied to the prediction of seasonal change in distributions. In this study, we aimed to build a species' distribution model for the Common Quail Coturnix coturnix, a farmland species that shows changes in its distribution in response to seasonal changes in habitat suitability. During the course of three breeding seasons we collected temporal replicates of presence-absence data in 13 sampling locations in four countries (Morocco, Portugal, Spain and France). We used generalized linear mixed models to relate the species' presence or absence to environmental variables and to the normalized difference vegetation index at each sampling location through the seasons, the latter variable being an indicator of within- and between-season habitat changes. The preferred model showed that occurrence was highly dependent on habitat changes associated with crop seasonality, as measured by the normalized difference vegetation index. Common Quail selected areas with dense vegetation and warm climate and tracked spatial changes in these two parameters. The model allows accurate mapping of within- and between-season distribution changes. Such changes are related to habitat variations caused mainly by drought and agricultural practices. Our results demonstrate that seasonal changes in farmland ecosystems can be incorporated into a simple distribution model, and our approach could be applied to other species to predict the effects of agricultural changes on the distribution of birds inhabiting farmland landscapes. © 2012 The Authors Ibis © 2012 British Ornithologists' Union.

Llegeix més

Prominent role of invasive species in avian biodiversity loss

Clavero M., Brotons L., Pons P., Sol D. (2009) Prominent role of invasive species in avian biodiversity loss. Biological Conservation. 142: 2043-2049.
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Doi: 10.1016/j.biocon.2009.03.034

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The rise of extinction rates associated with human activities has led to a growing interest in identifying extinction-prone taxa and extinction-promoting drivers. Previous work has identified habitat alterations and invasive species as the major drivers of recent bird extinctions. Here, we extend this work to ask how these human-driven impacts differentially affect extinction-prone taxa, and if any specific driver promotes taxonomic homogenization of avifauna. Like most previous studies, our analysis is based on global information of extinction drivers affecting threatened and extinct bird species from the IUCN Red List. Unlike previous studies, we employ a multivariate statistical framework that allows us to identify the main gradients of variation in extinction drivers. By using these gradients, we show that bird families with the highest extinction risk are primarily associated with threats posed by invasive species, once species richness and phylogeny are taken into account. As expected, the negative impact of invasive species was higher on island species, but our results also showed that it was particularly high in those species with small distribution ranges. On the other hand, mainland species and island species with large ranges tended to be affected by habitat destruction. Thus the impacts of invasive species promote the process of taxonomic homogenization among islands and between islands and continents. Consequently, introduced species may increase biotic homogenization not only directly, as generally believed, but also indirectly through their disproportional impact on endemic species imperilment. © 2009 Elsevier Ltd. All rights reserved.

Llegeix més

Random sampling, abundance-extinction dynamics and niche-filtering immigration constraints explain the generation of species richness gradients

Carnicer J., Brotons L., Sol D., De Cáceres M. (2008) Random sampling, abundance-extinction dynamics and niche-filtering immigration constraints explain the generation of species richness gradients. Global Ecology and Biogeography. 17: 352-362.
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Doi: 10.1111/j.1466-8238.2007.00380.x

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Aim: The paradigm that species' patterns of distribution, abundance and coexistence are the result of adaptations of the species to their niches has recently been challenged by evidence that similar patterns may be generated by simple random processes. We argue here that a better understanding of macroecological patterns requires an integration of both ecological and neutral stochastic approaches. We demonstrate the utility of such an integrative approach by testing the sampling hypothesis in a species-energy relationship of forest bird species. Location: A Mediterranean biome in Catalonia, Spain. Methods: To test the sampling hypothesis we designed a metacommunity model that reproduces the stochastic sampling from a regional pool to predict local species richness variation. Four conceptually different sampling procedures were evaluated. Results: We showed that stochastic sampling processes predicted a substantial part (over 40%) of the observed variation in species richness, but left considerable variation unexplained. This remaining variation in species richness may be better understood as the result of alternative ecological processes. First, the sampling model explained more variation in species richness when the probability that a species colonises a new locality was assumed to increase with its niche width, suggesting that ecological differences between species matter when it comes to explaining macroecological patterns. Second, extinction risk was significantly lower for species inhabiting high-energy regions, suggesting that abundance-extinction processes play a significant role in shaping species richness patterns. Main conclusions: We conclude that species-energy relationships may not simply be understood as a result of either ecological or random sampling processes, but more likely as a combination of both. © 2008 The Authors Journal compilation © 2008 Blackwell Publishing Ltd.

Llegeix més

Community-based processes behind species richness gradients: Contrasting abundance-extinction dynamics and sampling effects in areas of low and high productivity

Carnicer J., Brotons L., Sol D., Jordano P. (2007) Community-based processes behind species richness gradients: Contrasting abundance-extinction dynamics and sampling effects in areas of low and high productivity. Global Ecology and Biogeography. 16: 709-719.
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Doi: 10.1111/j.1466-8238.2007.00324.x

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Aim: To consider the role of local colonization and extinction rates in explaining the generation and maintenance of species richness gradients at the regional scale. Location: A Mediterranean biome (oak forests, deciduous forests, shrublands, pinewoods, firwoods, alpine heathlands, crops) in Catalonia, Spain. Methods: We analysed the relative importance of direct and indirect effects of community size in explaining species richness gradients. Direct sampling effects of community size on species richness are predicted by Hubbell's neutral theory of biodiversity and biogeography. The greater the number of individuals in a locality, the greater the number of species expected by random direct sampling effects. Indirect effects are predicted by the abundance-extinction hypothesis, which states that in more productive sites increased population densities and reduced extinction rates may lead to high species richness. The study system was an altitudinal gradient of forest bird species richness. Results: We found significant support for the existence of both direct and indirect effects of community size in species richness. Thus, both the neutral and the abundance-extinction hypotheses were supported for the altitudinal species richness gradient of forest birds in Catalonia. However, these mechanisms seem to drive variation in species richness only in low-productivity areas; in high-productivity areas, species richness was uncorrelated with community size and productivity measures. Main conclusions: Our results support the existence of a geographical mosaic of community-based processes behind species richness gradients, with contrasting abundance-extinction dynamics and sampling effects in areas of low and high productivity. © 2007 The Authors © 2007 Blackwell Publishing Ltd.

Llegeix més

Flexible dispersal strategies in native and non-native ranges: environmental quality and the ‘good–stay, bad–disperse’ rule

Hui C, Roura-Pascual N, Brotons L, Robinson RA, Evans KL (2012) Flexible dispersal strategies in native and non-native ranges: environmental quality and the ‘good–stay, bad–disperse’ rule. Ecography 35: 1024-1032.

Mapping from heterogeneous biodiversity monitoring data sources

Sardà-Palomera F, Brotons L, Villero D, Sierdsema H, Newson S, Jiguet F (2012) Mapping from heterogeneous biodiversity monitoring data sources. Biodiversity and Conservation 21: 2927-2948.

Reassessing global change research priorities in mediterranean terrestrial ecosystems: How far have we come and where do we go from here?

Doblas-Miranda E., Martinez-Vilalta J., Lloret F., Alvarez A., Avila A., Bonet F.J., Brotons L., Castro J., Curiel Yuste J., Diaz M., Ferrandis P., Garcia-Hurtado E., Iriondo J.M., Keenan T.F., Latron J., Llusia J., Loepfe L., Mayol M., More G., Moya D., Penuelas J., Pons X., Poyatos R., Sardans J., Sus O., Vallejo V.R., Vayreda J., Retana J. (0) Reassessing global change research priorities in mediterranean terrestrial ecosystems: How far have we come and where do we go from here?. Global Ecology and Biogeography. 24: 25-43.
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Doi: 10.1111/geb.12224

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Aim: Mediterranean terrestrial ecosystems serve as reference laboratories for the investigation of global change because of their transitional climate, the high spatiotemporal variability of their environmental conditions, a rich and unique biodiversity and a wide range of socio-economic conditions. As scientific development and environmental pressures increase, it is increasingly necessary to evaluate recent progress and to challenge research priorities in the face of global change. Location: Mediterranean terrestrial ecosystems. Methods: This article revisits the research priorities proposed in a 1998 assessment. Results: A new set of research priorities is proposed: (1) to establish the role of the landscape mosaic on fire-spread; (2) to further research the combined effect of different drivers on pest expansion; (3) to address the interaction between drivers of global change and recent forest management practices; (4) to obtain more realistic information on the impacts of global change and ecosystem services; (5) to assess forest mortality events associated with climatic extremes; (6) to focus global change research on identifying and managing vulnerable areas; (7) to use the functional traits concept to study resilience after disturbance; (8) to study the relationship between genotypic and phenotypic diversity as a source of forest resilience; (9) to understand the balance between C storage and water resources; (10) to analyse the interplay between landscape-scale processes and biodiversity conservation; (11) to refine models by including interactions between drivers and socio-economic contexts; (12) to understand forest-atmosphere feedbacks; (13) to represent key mechanisms linking plant hydraulics with landscape hydrology. Main conclusions: (1) The interactive nature of different global change drivers remains poorly understood. (2) There is a critical need for the rapid development of regional- and global-scale models that are more tightly connected with large-scale experiments, data networks and management practice. (3) More attention should be directed to drought-related forest decline and the current relevance of historical land use.

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