857 resultados para PROTECTED AREAS MANAGEMENT
Resumo:
In terms of changing flow and sediment regimes of rivers, dams are often regarded as the most dominant form of human impact on fluvial systems. Dams can decrease the flux of water and sediments leading to channel changes such as upstream aggradation and downstream degradation. The opposite effects occur when dams are removed. Channel degradation often requires further intervention in terms of river bed and bank protection works. The situation evolves more complex in river systems that are impacted by a series of dams due to feedback processes between the different system compartments. A number of studies have recently investigated geomorphic systems using connectivity approaches to improve the understanding of geomorphic system response to change. This paper presents a case study investigating the impact of dam construction, dam removal and dam-related river bed and bank protection measures on the sediment connectivity and channel morphology of the Fugnitz and the Kaja Rivers using a combination of DEM analyses, field surveys and landscape evolution modelling. For both river systems the results revealed low sediment connectivity accompanied by a fine river bed sediment facies in river sections upstream of active dams and of removed dams with protection measures. Contrarily, high sediment connectivity which was accompanied by a coarse river bed sediment facies was observed in river sections either located downstream of active dams or of removed dams with upstream protection. In terms of channel changes, significant channel degradation was examined at locations downstream of active dams and of removed dams. Channel bed and bank protection measures prevent erosion and channel slope recovery after dam removal. Landscape evolution modeling revealed a complex geomorphic response to dam construction and dam removal as sediment output rates and therefore geomorphic processes have been shown to act in a non-linear manner. These insights are deemed to have major implications for river management and conservation, as quality and state of riverine habitats are determined by channel morphology and river bed sediment composition.
Resumo:
The montane forests of Mount Kilimanjaro in Tanzania have been subjected to a long history of selective logging. However, since 1984 logging of indigenous trees is prohibited. Today, these forests allow us to evaluate the long-term effects of selective logging. We mapped the height and diameter at breast height (DBH) of all trees >10 cm DBH on 10 sites of 0.25 ha. Five sites represent non-logged forests, another five selectively logged forests. We tested whether forests were still visibly affected 30–40 years after selective logging in terms of their forest structure and tree diversity. Additionally we compared tree densities of different species guilds, including disturbance-indicator species, late-successional species and main timber species. Furthermore, we specifically compared the community size distributions of selectively logged and non-logged forests, first across all species and then for the most important timber species, Ocotea usambarensis, alone. 30–40 years after selective logging forests still showed a higher overall stem density, mainly due to higher relative abundances of small trees (<50 cm DBH) in general, and higher densities of small size class stems of late-successional species specifically. For O. usambarensis, the selectively logged sites harboured higher relative abundances of small trees and lower relative abundances of harvestable trees. The higher relative abundance of small O. usambarensis-stems in selectively logged forests appears promising for future forest recovery. Thus, outside protected areas, selective logging may be a sustainable management option if logging cycles are considerably longer than 40 years, enough large source trees remain, and the recruiting O. usambarensis individuals find open space for their establishment.
Resumo:
This study aims to evaluate the potential for impacts of ocean acidification on North Atlantic deep-sea ecosystems in response to IPCC AR5 Representative Concentration Pathways (RCPs). Deep-sea biota is likely highly vulnerable to changes in seawater chemistry and sensitive to moderate excursions in pH. Here we show, from seven fully coupled Earth system models, that for three out of four RCPs over 17% of the seafloor area below 500 m depth in the North Atlantic sector will experience pH reductions exceeding −0.2 units by 2100. Increased stratification in response to climate change partially alleviates the impact of ocean acidification on deep benthic environments. We report on major pH reductions over the deep North Atlantic seafloor (depth >500 m) and at important deep-sea features, such as seamounts and canyons. By 2100, and under the high CO2 scenario RCP8.5, pH reductions exceeding −0.2 (−0.3) units are projected in close to 23% (~15%) of North Atlantic deep-sea canyons and ~8% (3%) of seamounts – including seamounts proposed as sites of marine protected areas. The spatial pattern of impacts reflects the depth of the pH perturbation and does not scale linearly with atmospheric CO2 concentration. Impacts may cause negative changes of the same magnitude or exceeding the current target of 10% of preservation of marine biomes set by the convention on biological diversity, implying that ocean acidification may offset benefits from conservation/management strategies relying on the regulation of resource exploitation.
Resumo:
During November 2010–February 2011, we used camera traps to estimate the population density of Eurasian lynx Lynx lynx in Ciglikara Nature Reserve, Turkey, an isolated population in southwest Asia. Lynx density was calculated through spatial capture—recapture models. In a sampling eff ort of 1093 camera trap days, we identifi ed 15 independent individuals and estimated a density of 4.20 independent lynx per 100 km2, an unreported high density for this species. Camera trap results also indicated that the lynx is likely to be preying on brown hare Lepus europaeus, which accounted for 63% of the non-target species pictured. As lagomorph populations tend to fl uctuate, the high lynx density recorded in Ciglikara may be temporary and may decline with prey fl uctuation. Therefore we recommend to survey other protected areas in southwestern Turkey where lynx is known or assumed to exist, and continuously monitor the lynx populations with reliable methods in order to understand the populations structure and dynamics, defi ne sensible measures and management plans to conserve this important species.
Resumo:
Seamounts and knolls are 'undersea mountains', the former rising more than 1000 m from the sea floor. These features provide important habitats for aquatic predators, demersal deep-sea fish and benthic invertebrates. However most seamounts have not been surveyed and their numbers and locations are not well known. Previous efforts to locate and quantify seamounts have used relatively coarse bathymetry grids. Here we use global bathymetric data at 30 arc-second resolution to identify seamounts and knolls. We identify 33,452 seamounts and 138,412 knolls, representing the largest global set of identified seamounts and knolls to date. We compare estimated seamount numbers, locations, and depths with validation sets of seamount data from New Zealand and Azores. This comparison indicates the method we apply finds 94% of seamounts, but may overestimate seamount numbers along ridges and in areas where faulting and seafloor spreading creates highly complex topography. The seamounts and knolls identified herein are significantly geographically biased towards areas surveyed with ship-based soundings. As only 6.5% of the ocean floor has been surveyed with soundings it is likely that new seamounts will be uncovered as surveying improves. Seamount habitats constitute approximately 4.7% of the ocean floor, whilst knolls cover 16.3%. Regional distribution of these features is examined, and we find a disproportionate number of productive knolls, with a summit depth of <1.5 km, located in the Southern Ocean. Less than 2% of seamounts are within marine protected areas and the majority of these are located within exclusive economic zones with few on the High Seas. The database of seamounts and knolls resulting from this study will be a useful resource for researchers and conservation planners.
Resumo:
Colombia es uno de los países denominados megadiversos biológica y culturalmente. Presenta a su interior la mayor extensión de páramos del mundo, los cuales son considerados fábricas de agua del planeta y hábitats de rica diversidad biológica. Por otro lado, la ocupación humana de los páramos colombianos ha generado conflictos entre las normativas ambientales vigentes y los usos productivos del suelo. El presente artículo analiza las alternativas aplicadas ante el conflicto entre autoridades ambientales de áreas protegidas y habitantes de los páramos en Colombia. Se encontraron dos tipos de alternativas: la primera plantea la concesión de servicios ecoturísticos en los parques naturales y la compra de tierras por parte de sociedades de economía mixta. La segunda plantea el abandono de las actividades productivas de los agricultores, mediado por procesos educativos o de cumplimiento de las normas ambientales vigentes, so pena de enfrentar acciones punitivas por parte del Estado. Este trabajo presenta una tercera alternativa, que parte de la crítica a las dos anteriores e incluye diferentes estrategias: planes de manejo comunitario con tiempo y financiación institucional pertinente, aplicación de modelos agroecológicos y rescate de la memoria biocultural y cambios en la estructura agraria.
Resumo:
La Bahía de Samborombón (provincia de Buenos Aires, Argentina) constituye un área de interface entre el ámbito fluvial-marítimo (desembocadura del Río de la Plata en el Mar Argentino) y el terrestre. La franja litoral sur de la misma fue sistemáticamente marginada por los procesos de valorización que dominaron el territorio pampeano. Sin embargo, en los últimos 30 años se han constituido diferentes áreas protegidas, correspondientes a diversas jurisdicciones del sector público (nacional, provincial, municipal) y privado (ONGs). El objetivo de este trabajo apunta a poner de relieve las problemáticas generadas en torno a la valorización del territorio y la gestión de las mencionadas áreas protegidas, en el marco de las actividades económicas dominantes (ganadería, pesca y turismo)
Resumo:
Antipatharia are a diverse group of corals with many species found in deep water. Many Antipatharia are habitat for associates, have extreme longevity and some species can occur beyond 8500 m depth. As they are major constituents of 'coral gardens', which are Vulnerable Marine Ecosystems (VMEs), knowledge of their distribution and environmental requirements is an important pre-requisite for informed conservation planning particularly where the expense and difficulty of deep-sea sampling prohibits comprehensive surveys. This study uses a global database of Antipatharia distribution data to perform habitat suitability modelling using the Maxent methodology to estimate the global extent of black coral habitat suitability. The model of habitat suitability is driven by temperature but there is notable influence from other variables of topography, surface productivity and oxygen levels. This model can be used to predict areas of suitable habitat, which can be useful for conservation planning. The global distribution of Antipatharia habitat suitability shows a marked contrast with the distribution of specimen observations, indicating that many potentially suitable areas have not been sampled, and that sampling effort has been disproportionate to shallow, accessible areas inside marine protected areas (MPAs). Although 25% of Antipatharia observations are located in MPAs, only 7-8% of predicted suitable habitat is protected, which is short of the Convention on Biological Diversity target to protect 10% of ocean habitats by 2020.
Resumo:
Colombia es uno de los países denominados megadiversos biológica y culturalmente. Presenta a su interior la mayor extensión de páramos del mundo, los cuales son considerados fábricas de agua del planeta y hábitats de rica diversidad biológica. Por otro lado, la ocupación humana de los páramos colombianos ha generado conflictos entre las normativas ambientales vigentes y los usos productivos del suelo. El presente artículo analiza las alternativas aplicadas ante el conflicto entre autoridades ambientales de áreas protegidas y habitantes de los páramos en Colombia. Se encontraron dos tipos de alternativas: la primera plantea la concesión de servicios ecoturísticos en los parques naturales y la compra de tierras por parte de sociedades de economía mixta. La segunda plantea el abandono de las actividades productivas de los agricultores, mediado por procesos educativos o de cumplimiento de las normas ambientales vigentes, so pena de enfrentar acciones punitivas por parte del Estado. Este trabajo presenta una tercera alternativa, que parte de la crítica a las dos anteriores e incluye diferentes estrategias: planes de manejo comunitario con tiempo y financiación institucional pertinente, aplicación de modelos agroecológicos y rescate de la memoria biocultural y cambios en la estructura agraria.
Resumo:
Colombia es uno de los países denominados megadiversos biológica y culturalmente. Presenta a su interior la mayor extensión de páramos del mundo, los cuales son considerados fábricas de agua del planeta y hábitats de rica diversidad biológica. Por otro lado, la ocupación humana de los páramos colombianos ha generado conflictos entre las normativas ambientales vigentes y los usos productivos del suelo. El presente artículo analiza las alternativas aplicadas ante el conflicto entre autoridades ambientales de áreas protegidas y habitantes de los páramos en Colombia. Se encontraron dos tipos de alternativas: la primera plantea la concesión de servicios ecoturísticos en los parques naturales y la compra de tierras por parte de sociedades de economía mixta. La segunda plantea el abandono de las actividades productivas de los agricultores, mediado por procesos educativos o de cumplimiento de las normas ambientales vigentes, so pena de enfrentar acciones punitivas por parte del Estado. Este trabajo presenta una tercera alternativa, que parte de la crítica a las dos anteriores e incluye diferentes estrategias: planes de manejo comunitario con tiempo y financiación institucional pertinente, aplicación de modelos agroecológicos y rescate de la memoria biocultural y cambios en la estructura agraria.
Resumo:
La Bahía de Samborombón (provincia de Buenos Aires, Argentina) constituye un área de interface entre el ámbito fluvial-marítimo (desembocadura del Río de la Plata en el Mar Argentino) y el terrestre. La franja litoral sur de la misma fue sistemáticamente marginada por los procesos de valorización que dominaron el territorio pampeano. Sin embargo, en los últimos 30 años se han constituido diferentes áreas protegidas, correspondientes a diversas jurisdicciones del sector público (nacional, provincial, municipal) y privado (ONGs). El objetivo de este trabajo apunta a poner de relieve las problemáticas generadas en torno a la valorización del territorio y la gestión de las mencionadas áreas protegidas, en el marco de las actividades económicas dominantes (ganadería, pesca y turismo)
Resumo:
Colombia es uno de los países denominados megadiversos biológica y culturalmente. Presenta a su interior la mayor extensión de páramos del mundo, los cuales son considerados fábricas de agua del planeta y hábitats de rica diversidad biológica. Por otro lado, la ocupación humana de los páramos colombianos ha generado conflictos entre las normativas ambientales vigentes y los usos productivos del suelo. El presente artículo analiza las alternativas aplicadas ante el conflicto entre autoridades ambientales de áreas protegidas y habitantes de los páramos en Colombia. Se encontraron dos tipos de alternativas: la primera plantea la concesión de servicios ecoturísticos en los parques naturales y la compra de tierras por parte de sociedades de economía mixta. La segunda plantea el abandono de las actividades productivas de los agricultores, mediado por procesos educativos o de cumplimiento de las normas ambientales vigentes, so pena de enfrentar acciones punitivas por parte del Estado. Este trabajo presenta una tercera alternativa, que parte de la crítica a las dos anteriores e incluye diferentes estrategias: planes de manejo comunitario con tiempo y financiación institucional pertinente, aplicación de modelos agroecológicos y rescate de la memoria biocultural y cambios en la estructura agraria.
Resumo:
La Bahía de Samborombón (provincia de Buenos Aires, Argentina) constituye un área de interface entre el ámbito fluvial-marítimo (desembocadura del Río de la Plata en el Mar Argentino) y el terrestre. La franja litoral sur de la misma fue sistemáticamente marginada por los procesos de valorización que dominaron el territorio pampeano. Sin embargo, en los últimos 30 años se han constituido diferentes áreas protegidas, correspondientes a diversas jurisdicciones del sector público (nacional, provincial, municipal) y privado (ONGs). El objetivo de este trabajo apunta a poner de relieve las problemáticas generadas en torno a la valorización del territorio y la gestión de las mencionadas áreas protegidas, en el marco de las actividades económicas dominantes (ganadería, pesca y turismo)
Resumo:
Risk analyses indicate that more than 90% of the world's reefs will be threatened by climate change and local anthropogenic impacts by the year 2030 under "business-as-usual" climate scenarios. Increasing temperatures and solar radiation cause coral bleaching that has resulted in extensive coral mortality. Increasing carbon dioxide reduces seawater pH, slows coral growth, and may cause loss of reef structure. Management strategies include establishment of marine protected areas with environmental conditions that promote reef resiliency. However, few resilient reefs have been identified, and resiliency factors are poorly defined. Here we characterize the first natural, non-reef coral refuge from thermal stress and ocean acidification and identify resiliency factors for mangrove-coral habitats. We measured diurnal and seasonal variations in temperature, salinity, photosynthetically active radiation (PAR), and seawater chemistry; characterized substrate parameters; and examined water circulation patterns in mangrove communities where scleractinian corals are growing attached to and under mangrove prop roots in Hurricane Hole, St. John, US Virgin Islands. Additionally, we inventoried the coral species and quantified incidences of coral bleaching, mortality, and recovery for two major reef-building corals, Colpophyllia natans and Diploria labyrinthiformis, growing in mangrove-shaded and exposed (unshaded) areas. Over 30 species of scleractinian corals were growing in association with mangroves. Corals were thriving in low-light (more than 70% attenuation of incident PAR) from mangrove shading and at higher temperatures than nearby reef tract corals. A higher percentage of C. natans colonies were living shaded by mangroves, and no shaded colonies were bleached. Fewer D. labyrinthiformis colonies were shaded by mangroves, however more unshaded colonies were bleached. A combination of substrate and habitat heterogeneity, proximity of different habitat types, hydrographic conditions, and biological influences on seawater chemistry generate chemical conditions that buffer against ocean acidification. This previously undocumented refuge for corals provides evidence for adaptation of coastal organisms and ecosystem transition due to recent climate change. Identifying and protecting other natural, non-reef coral refuges is critical for sustaining corals and other reef species into the future.
Resumo:
Understanding species distribution patterns and the corresponding environmental determinants is a crucial step in the development of effective strategies for the conservation and management of plant communities and ecosystems. Therefore, a central prerequisite is the biogeographical and macroecological analysis of factors and processes that determine contemporary, potential, as well as future geographic distribution of species. This thesis has been conducted in the framework of the BIOMAPS-BIOTA project at the Nees Institute of Biodiversity of Plants, which was funded by the German Federal Ministry of Education and Research (BMBF). The study investigated patterns of plants species richness and phytogeographic regions under contemporary environmental conditions and forecasted future climate change in the area of West Africa covering five countries: Benin, Burkina Faso, Côte d'Ivoire, Ghana and Togo. Firstly, geographic patterns of vascular plant species richness have been depicted at a relatively fine spatial resolution based on the potential distribution of 3,393 species. Species richness is closely related to the steep climatic gradient existing in the region with a high concentration of species in the most humid areas in the south and decreases towards the northern drier areas. The investigation of the effectiveness of the existing network of protected areas shows an overall good coverage of species in the study area. However, the proportion of covered species is considerably lower at national extent for some countries, thus calling for more protected areas in order to cover adequately a maximum number of plants species in these countries. Secondly, based on the potential distribution range of vascular plant species, seven phytogeographic regions have been delineated that broadly reflect the vegetation zones as defined by White (1983). However notable differences to the delineation of White (1983) occur at the margins of some regions. Corresponding to a general southward shifted of all regions. And expansion of the Sahel vegetation zone is observed in the north, while the rainforest zone is decreased in the very south.This is alarming since the rainforest shelters a high number of species and a high proportion of range-restricted or endemic species, despite their relatively small extent compared to the other regions. Finally, the evaluation of the potential impact of climate change on plant species richness in the study area, results in a severe loss of future suitable habitat for up to 50% of species per grid cell, particularly in the rainforest region. Moreover, the analysis of the possible shift of phytogeographic regions shows in general a strong deterioration of the West African rainforest. In contrast the drier areas are expanding continuously, although a slight gain in species number can be observed in some particular regions. The overall lesson to retain from the results of this study is that the West African rainforest should be fixed as a high priority area for the conservation of biodiversity of plants, since it is subject to severe contemporary and projected future threats.