9 resultados para 771006 Remnant vegetation and protected conservation areas

em Universidad de Alicante


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La superficie protegida ha crecido, en poco más de un siglo, de forma muy rápida, logrando alcanzar cifras significativas que, no obstante, pueden oscilar de forma muy notable entre unos países y otros. Este interés por proteger los espacios naturales responde, en el contexto actual, a la consecución de una amplia serie de fines de carácter científico, educativo, recreativo y socioeconómico. Como consecuencia de ello, ha surgido un nuevo escenario en el que determinados aprovechamientos tradicionales se están viendo afectados. La caza es, sin duda, uno de los mejores ejemplos de actividad tradicional que se está viendo perjudicada por este proceso. Con estos antecedentes, en el presente trabajo se analiza con carácter general la situación de los espacios naturales protegidos en Extremadura en relación con la actividad cinegética. Este análisis se lleva a cabo teniendo en cuenta que un tercio de la superficie regional está protegida por algunas de las figuras existentes y que, además, estos espacios se distribuyen por áreas en las que la caza ha sido un aprovechamiento tradicional que ha contribuido a mantener los espacios en mejor estado de conservación.

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Understanding the ecology of migratory birds during the non-breeding season is necessary for ensuring their conservation. Using satellite telemetry data we describe winter ranging behaviour and movements of pallid harriers Circus macrourus that bred in Kazakhstan. We developed an ecological niche model for the species in Africa, to identify the most suitable wintering areas for pallid harriers and the importance of habitat in determining the location of those areas. We also assessed how well represented suitable areas are in the network of protected areas. Individual harriers showed relatively high fidelity to wintering areas but with potential for interannual changes. The ecological niche model highlighted the importance of open habitats with natural vegetation. Most suitable areas for the species were located in eastern Africa. Suitable areas had a patchy distribution but were relatively well included in the network of protected areas. The preferential use of habitats with natural vegetation by wintering pallid harriers and the patchiness of the most suitable areas highlight the harrier's vulnerability to land-use changes and the associated loss of natural vegetation in Africa. Conservation of harriers could be enhanced by preserving natural grasslands within protected areas and improving habitat management in the human-influenced portions of the species’ core wintering areas.

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We examined distribution and breeding success of semi-colonial Montagu’s Harriers (Circus pygargus) in relation to habitat in Castellón province (eastern Spain). Breeding areas used by harriers at a 1-km2 scale were characterised by having intermediate percentages of scrub cover, their nesting habitat, and also had intermediate coverage of herbaceous crops and non-irrigated orchards. Out of all habitat variables considered, only the percentage of herbaceous crops within 500 m from individual nests had a positive and significant effect on breeding output of the species, suggesting that this habitat may be efficiently used by harriers to forage. Breeding output was also related to laying date and number of breeding neighbours within 500 m around nests, with pairs laying later and having a higher number of breeding neighbours showing lower fledged brood sizes. Number of neighbours (but not laying date) was positively related to scrub cover within 500 m and to cover of herbaceous crops within 2,000 m. Conservation actions for Montagu’s Harrier in the study area should be aimed at preserving areas of scrub with nearby presence of herbaceous crops or natural grasslands. However, habitat improvement for semi-colonial species such as Montagu’s Harrier may not result in a change of species distribution area, and good habitat areas may remain unoccupied, as social factors like presence of conspecifics play an important role in breeding area selection for these species.

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The high rate of amphibian endemism and the severe habitat modification in the Caribbean islands make them an ideal place to test if the current protected areas network might protect this group. In this study, we model distribution and map species richness of the 40 amphibian species from eastern Cuba with the objectives of identify hotspots, detect gaps in species representation in protected areas, and select additional areas to fill these gaps. We used two modeling methods, Maxent and Habitat Suitability Models, to reach a consensus distribution map for each species, then calculate species richness by combining specific models and finally performed gap analyses for species and hotspots. Our results showed that the models were robust enough to predict species distributions and that most of the amphibian hotspots were represented in reserves, but 50 percent of the species were incompletely covered and Eleutherodactylus rivularis was totally uncovered by the protected areas. We identified 1441 additional km2 (9.9% of the study area) that could be added to the current protected areas, allowing the representation of every species and all hotspots. Our results are relevant for the conservation planning in other Caribbean islands, since studies like this could contribute to fill the gaps in the existing protected areas and to design a future network. Both cases would benefit from modeling amphibian species distribution using available data, even if they are incomplete, rather than relying only in the protection of known or suspected hotspots.

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Moderate resolution remote sensing data, as provided by MODIS, can be used to detect and map active or past wildfires from daily records of suitable combinations of reflectance bands. The objective of the present work was to develop and test simple algorithms and variations for automatic or semiautomatic detection of burnt areas from time series data of MODIS biweekly vegetation indices for a Mediterranean region. MODIS-derived NDVI 250m time series data for the Valencia region, East Spain, were subjected to a two-step process for the detection of candidate burnt areas, and the results compared with available fire event records from the Valencia Regional Government. For each pixel and date in the data series, a model was fitted to both the previous and posterior time series data. Combining drops between two consecutive points and 1-year average drops, we used discrepancies or jumps between the pre and post models to identify seed pixels, and then delimitated fire scars for each potential wildfire using an extension algorithm from the seed pixels. The resulting maps of the detected burnt areas showed a very good agreement with the perimeters registered in the database of fire records used as reference. Overall accuracies and indices of agreement were very high, and omission and commission errors were similar or lower than in previous studies that used automatic or semiautomatic fire scar detection based on remote sensing. This supports the effectiveness of the method for detecting and mapping burnt areas in the Mediterranean region.

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The “dehesa” is a traditional Iberian agrosilvopastoral ecosystem characterized by the presence of old scattered trees that are considered as “keystone-structures”, which favor the presence of a wide range of biodiversity. We show the high diversity of saproxylic beetles and syrphids (Diptera) in this ecosystem, including red-listed species. We analyzed whether saproxylic species distribution in the “dehesa” was affected by tree density per hectare, dominant tree species or vegetation coverage. Species diversity did not correlate with tree density; however, it was affected by tree species and shrub coverage but in a different way for each taxon. The highest beetle diversity was linked to Quercus pyrenaica, the most managed tree species, with eight indicator species. In contrast, Q. rotundifolia hosted more species of saproxylic syrphids. Regarding vegetation coverage, shrub coverage was the only variable that affected insect richness, again in a different way for both taxa. In contrast, beetle species composition was only affected by dominant tree species whereas syrphid species composition was not affected by tree species or shrub coverage. We concluded that the high diversity of saproxylic insects in the “dehesa” is related to its long history of agrosilvopastoral management, which has generated landscape heterogeneity and preserved old mature trees. However, the richness and composition of different taxa of insects respond in different ways to tree species and vegetation coverage. Consequently, conservation strategies should try to maintain traditional management, and different saproxylic taxa should be used to monitor the effect of management on saproxylic diversity.

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Aim of study. Orchidaceae has the largest number of species of any family in the plant kingdom. This family is subject to a high risk of extinction in natural environments, such as natural parks and protected areas. Recent studies have shown the prevalence of many species of orchids to be linked to fungal soil diversity, due to their myco-heterotrophic behaviour. Plant communities determine fungal soil diversity, and both generate optimal conditions for orchid development. Area of study. The work was carried out in n the two most important natural parks in Alicante (Font Roja and Sierra Mariola), in South-eastern of Spain. Material and Methods. We designed a molecular tool to monitor the presence of Russula spp. in soil and orchids roots, combined with phytosociological methods. Main results. Using a PCR-based method, we detected the presence in the soil and Limodorum abortivum orchid roots of the mycorrhizal fungi Russula spp. The species with highest coverage was Quercus rotundifolia in areas where the orchid was present. Research highlights. We present a useful tool based on PCR to detect the presence of Russula spp. in a natural environment. These results are consistent with those obtained in different studies that linked the presence of the mycorrhizal fungi Russula spp. in roots of the species Limodorum and the interaction between these fungal species and Quercus ilex trees in Mediterranean forest environments.

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La evolución del arbolado en la Península Ibérica pasó por numerosos episodios que le condujeron a una situación grave de deforestación. Tras varios intentos de reforestación en épocas distintas, finalmente la apuesta definitiva se produciría con la creación del Patrimonio Forestal del Estado y el Plan Nacional de Repoblación Forestal de España de 1939. La sustitución del PFE por el ICONA en 1971, supuso un nuevo contexto, en el que se puso en duda tanto la actuación repobladora, como las especies utilizadas, principalmente del género Pinus. Este trabajo trata de poner en valor la información que aportan distintas corrientes científicas, la botánica, la biogeografía, paleobotánica y los datos de otros estudios realizados en numerosos yacimientos arqueológicos en Andalucía, especialmente en la zona oriental. Estos trabajos ponen de manifiesto la presencia de especies del género Pinus en distintos periodos geológicos, con avances y retrocesos del binomio Pinus-Quercus, durante períodos más o menos extensos. La repoblación forestal supuso un avance a una de esas situaciones, que dió como resultado el marco de nuevas intervenciones de manejo del bosque por la Administración Andaluza, siendo las exigencias de conservación prioritarias en la gestión de los espacios forestales, muchos de ellos declarados Espacios Protegidos. Se trata pues, de poner en valor aquellas actuaciones que dieron lugar a la nueva situación en la que se apuesta por la conservación y en la que juegan un papel importante la genética y la productividad de las especies utilizadas en las intervenciones forestales.

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A criação de espaços territoriais especialmente protegidos é uma estratégia utilizada pelo homem desde a antiguidade, objetivando a reserva de áreas com características naturais necessárias à manutenção ou à reprodução cultural de populações humanas específicas, regulando e limitando o acesso e a apropriação de certos recursos e/ou reservando-os para usos ou futuros. Os processos de criação dessas “áreas especialmente protegidas” foram contudo intensificados, no final do século XX, com a percepção da finitude dos recursos naturais, e acelerados pelo florescimento e a consolidação do capitalismo, agora “globalizado”. Quando tais processos, são orientados por interesses diversos de grupos sociais hegemônicos, são comuns não só a desestruturação do modo de vida dos usuários dos recursos naturais tradicionalmente relacionados aos “territórios especiais”, como também a expulsão de grupos não-hegemônicos neles já instalados, sempre que suas práticas culturais sejam consideradas como incompatíveis com os fins e os objetivos da área que se pretende proteger. Entre os tipos de área especialmente protegida estabelecidos pela legislação brasileira, encontram-se as Unidades de Conservação da Natureza (UC). Criadas por Lei com o objetivo de conservar a biodiversidade brasileira, as UC vem sendo palco de diversos conflitos ambientais envolvendo populações tradicionais em todos os biomas brasileiros, mas pode ser mais facilmente evidenciada na Amazônia, aonde a megabiodiversidade a proteger se sobrepõe a territórios ocupados por diversas etnias indígenas e outros povos tradicionais. Os conflitos são intensificados quando a categoria de manejo da UC criada restringe o acesso e altera os modos de apropriação e/ou dos usos tradicionais dos recursos naturais da área por parte dos residentes, inclusive impedindo a continuidade da permanência das populações no interior da UC, no caso o grupo das UC de Proteção Integral. À luz dos debates que vem sendo travados no campo da ecologia política, tais processos conflituosos estariam associados à desterritorialização dos grupos afetados pela criação da UC, nos quais o Estado brasileiro seria o responsável direto. Independentemente das diversas abordagens acadêmicas para o conceito de “território”, entende-se atualmente que a territorialização e a desterritorialização (com consequente reterritorialização) são processos interrelacionados e circularmente conectados, não podendo ser compreendidos separadamente. Assim, o objetivo do presente trabalho é contribuir para a compreensão desses processos de des-re-terrritorialização, avaliando como alguns mecanismos previstos na Lei do Sistema Nacional das Unidades de Conservação para o reassentamento das populações anteriormente residentes vem sendo aplicados, no sentido de promover processos de reterritorialização. As reflexões apresentadas se dão a partir do caso dos ribeirinhos e colonos residentes na Estação Ecológica da Terra do Meio, Pará, Brasil. A partir da avaliação, são propostas alternativas para minimizar a situação de injustiça ambiental na qual se encontram esses atores sociais específicos.