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Respostas de asssembléias de formigas à perturbação antrópica na Mata Atlântica do sudeste do Brasil; Responses of ant assemblages to human disturbance in the Atlantic Forest in southeastern Brazil

Tatiane Gisele Alves
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 16/12/2011 Português
Relevância na Pesquisa
46.13%
A maior parte dos ambientes naturais têm sido convertidos para uso humano. Estas mudanças estão ocorrendo num ritmo nunca antes experimentado pela natureza. O aumento do conhecimento sobre a estrutura e o funcionamento dos ecossistemas auxilia na busca de respostas de como e que forma estas ações estão afetando os sistemas naturais, e consequentemente no planejamento de melhores estratégias de conservação. Uma das maneiras de acessar os processos ecológicos que são difíceis de monitorar é buscar grupos ou organismos que facilitem o entendimento destas intervenções. A sensibilidade das assembleias de formigas, combinada com a sua importância funcional e amostragem fácil, fazem delas bons organismos para estudos de conservação. O estudo avaliou a estrutura das assembleias de formigas em três unidades de conservação na Floresta Atlântica. As formigas foram amostradas em uma floresta contínua no Parque Estadual da Serra do Mar, sudeste do Brasil, em áreas mais preservadas e menos preservadas. O objetivo foi determinar se a riqueza, a composição e a abundância destes organismos diferem entre as áreas contrastantes em relação ao grau de perturbação antrópica. Os resultados mostraram que a riqueza não foi afetada nas áreas com diferentes históricos de perturbação...

Invasibility of Mediterranean-Climate Rivers by Non-Native Fish: The Importance of Environmental Drivers and Human Pressures.

Ilhéu, Maria; Matono, Paula; Bernardo, João
Fonte: PLOSONE Publicador: PLOSONE
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.04%
Invasive species are regarded as a biological pressure to natural aquatic communities. Understanding the factors promoting successful invasions is of great conceptual and practical importance. From a practical point of view, it should help to prevent future invasions and to mitigate the effects of recent invaders through early detection and prioritization of management measures. This study aims to identify the environmental determinants of fish invasions in Mediterraneanclimate rivers and evaluate the relative importance of natural and human drivers. Fish communities were sampled in 182 undisturbed and 198 disturbed sites by human activities, belonging to 12 river types defined for continental Portugal within the implementation of the European Union’s Water Framework Directive. Pumpkinseed sunfish, Lepomis gibbosus (L.), and mosquitofish, Gambusia holbrooki (Girard), were the most abundant non-native species (NNS) in the southern river types whereas the Iberian gudgeon, Gobio lozanoi Doadrio and Madeira, was the dominant NNS in the north/centre. Small northern mountain streams showed null or low frequency of occurrence and abundance of NNS, while southern lowland river types with medium and large drainage areas presented the highest values. The occurrence of NNS was significantly lower in undisturbed sites and the highest density of NNS was associated with high human pressure. Results from variance partitioning showed that natural environmental factors determine the distribution of the most abundant NNS while the increase in their abundance and success is explained mainly by human-induced disturbance factors. This study stresses the high vulnerability of the warm water lowland river types to non-native fish invasions...

Evidences that human disturbance simplify the ant fauna associated a Stachytarpheta glabra Cham. (Verbenaceae) compromising the benefits of ant-plant mutualism

Barbosa,BC.; Fagundes,R.; Silva,LF.; Tofoli,JFV.; Santos,AM.; Imai,BYP.; Gomes,GG.; Hermidorff,MM.; Ribeiro,SP.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2015 Português
Relevância na Pesquisa
46.07%
Interaction among species, like ants and plants through extrafloral nectaries (EFNs), are important components of ecological communities’ evolution. However, the effect of human disturbance on such specific interactions and its ecological consequences is poorly understood. This study evaluated the outcomes of mutualism between ants and the EFN-bearing plant Stachytarpheta glabra under anthropogenic disturbance. We compared the arthropod fauna composition between two groups of twenty plant individuals, one in an area disturbed by human activities and one in a preserved area. We also check the plant investment in herbivory defense and the consequential leaf damage by herbivore. Our results indicate that such disturbances cause simplification of the associated fauna and lack of proper ant mutualist. This led to four times more herbivory on plants of disturbed areas, despite the equal amount of EFN and ant visitors and low abundance of herbivores. The high pressure of herbivory may difficult the re-establishment of S. glabra, an important pioneer species in ferruginous fields, therefore it may affect resilience of this fragile ecological community.

Human disturbance alters endocrine and immune responses in the Galapagos marine iguana (Amblyrhynchus cristatus)

French, Susannah S; DeNardo, Dale F.; Greives, Timothy J.; Strand, Christine R.; Demas, Gregory E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.24%
Anthropogenic disturbance is a relevant and widespread facilitator of environmental change and there is clear evidence that it impacts natural populations. While population-level responses to major anthropogenic changes have been well studied, individual physiological responses to mild disturbance can be equally critical to the long-term survival of a species, yet they remain largely unexamined. The current study investigated the impact of seemingly low-level anthropogenic disturbance (ecotourism) on stress responsiveness and specific fitness-related immune measures in different breeding stages of the marine iguana (Amblyrhynchus cristatus). Specifically, we found stress-induced elevations in plasma corticosterone among tourist-exposed populations relative to undisturbed populations. We also found changes in multiple immunological responses associated with stress-related effects of human disturbance, including bacterial killing ability, cutaneous wound healing, and hemolytic complement activity, and the responses varied according to reproductive state. By identifying health-related consequences of human disturbance, this study provides critical insight into the conservation of a well-known species that has a very distinct ecology. The study also broadens the foundation of knowledge needed to understand the global significance of various levels of human disturbance.

Human Disturbance Influences Reproductive Success and Growth Rate in California Sea Lions (Zalophus californianus)

French, Susannah S.; González-Suárez, Manuela; Young, Julie K.; Durham, Susan; Gerber, Leah R.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 16/03/2011 Português
Relevância na Pesquisa
46.2%
The environment is currently undergoing changes at both global (e.g., climate change) and local (e.g., tourism, pollution, habitat modification) scales that have the capacity to affect the viability of animal and plant populations. Many of these changes, such as human disturbance, have an anthropogenic origin and therefore may be mitigated by management action. To do so requires an understanding of the impact of human activities and changing environmental conditions on population dynamics. We investigated the influence of human activity on important life history parameters (reproductive rate, and body condition, and growth rate of neonate pups) for California sea lions (Zalophus californianus) in the Gulf of California, Mexico. Increased human presence was associated with lower reproductive rates, which translated into reduced long-term population growth rates and suggested that human activities are a disturbance that could lead to population declines. We also observed higher body growth rates in pups with increased exposure to humans. Increased growth rates in pups may reflect a density dependent response to declining reproductive rates (e.g....

Co-Occurrence Patterns of Common and Rare Leaf-Litter Frogs, Epiphytic Ferns and Dung Beetles across a Gradient of Human Disturbance

Oldekop, Johan A.; Bebbington, Anthony J.; Truelove, Nathan K.; Tysklind, Niklas; Villamarín, Santiago; Preziosi, Richard F.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 11/06/2012 Português
Relevância na Pesquisa
46.15%
Indicator taxa are commonly used to identify priority areas for conservation or to measure biological responses to environmental change. Despite their widespread use, there is no general consensus about the ability of indicator taxa to predict wider trends in biodiversity. Many studies have focused on large-scale patterns of species co-occurrence to identify areas of high biodiversity, threat or endemism, but there is much less information about patterns of species co-occurrence at local scales. In this study, we assess fine-scale co-occurrence patterns of three indicator taxa (epiphytic ferns, leaf litter frogs and dung beetles) across a remotely sensed gradient of human disturbance in the Ecuadorian Amazon. We measure the relative contribution of rare and common species to patterns of total richness in each taxon and determine the ability of common and rare species to act as surrogate measures of human disturbance and each other. We find that the species richness of indicator taxa changed across the human disturbance gradient but that the response differed among taxa, and between rare and common species. Although we find several patterns of co-occurrence, these patterns differed between common and rare species. Despite showing complex patterns of species co-occurrence...

Human disturbance and stage-specific habitat requirements influence snowy plover site occupancy during the breeding season

Webber, Alyson F; Heath, Julie A; Fischer, Richard A
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.33%
Habitat use has important consequences for avian reproductive success and survival. In coastal areas with recreational activity, human disturbance may limit use of otherwise suitable habitat. Snowy plovers Charadrius nivosus have a patchy breeding distribution along the coastal areas on the Florida Panhandle, USA. Our goal was to determine the relative effects of seasonal human disturbance and habitat requirements on snowy plover habitat use. We surveyed 303 sites for snowy plovers, human disturbance, and habitat features between January and July 2009 and 2010. We made multiple visits during three different sampling periods that corresponded to snowy plover breeding: pre-breeding, incubation, and brood-rearing and used multi-season occupancy models to examine whether human disturbance, habitat features, or both influenced site occupancy, colonization (probability of transition from an unoccupied site to an occupied site), and extinction (probability of transition from an occupied site to an unoccupied site). Snowy plover site occupancy and colonization was negatively associated with human disturbance and site extinction was positively associated with human disturbance. Interdune vegetation had a negative effect on occupancy and colonization...

Climate Change and Human Disturbance Can Lead to Local Extinction of Alpine Rock Ptarmigan: New Insight from the Western Italian Alps

Imperio, Simona; Bionda, Radames; Viterbi, Ramona; Provenzale, Antonello
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 19/11/2013 Português
Relevância na Pesquisa
46.13%
Alpine grouses are particularly vulnerable to climate change due to their adaptation to extreme conditions and to their relict distributions in the Alps where global warming has been particularly marked in the last half century. Grouses are also currently threatened by habitat modification and human disturbance, and an assessment of the impact of multiple stressors is needed to predict the fate of Alpine populations of these birds in the next decades. We estimated the effect of climate change and human disturbance on a rock ptarmigan population living in the western Italian Alps by combining an empirical population modelling approach and stochastic simulations of the population dynamics under the a1B climate scenario and two different disturbance scenarios, represented by the development of a ski resort, through 2050.The early appearance of snow-free ground in the previous spring had a favorable effect on the rock ptarmigan population, probably through a higher reproductive success. On the contrary, delayed snowfall in autumn had a negative effect possibly due to a mismatch in time to molt to white winter plumage which increases predation risk. The regional climate model PROTHEUS does not foresee any significant change in snowmelt date in the study area...

Out of sight but not out of harm’s way: Human disturbance reduces reproductive success of a cavity-nesting seabird

Watson, Hannah; Bolton, Mark; Monaghan, Pat
Fonte: Applied Science Publishers [etc.] Publicador: Applied Science Publishers [etc.]
Tipo: Artigo de Revista Científica
Publicado em /06/2014 Português
Relevância na Pesquisa
46.15%
While negative effects of human disturbance on animals living above the ground have been widely reported, few studies have considered effects on animals occupying cavities or burrows underground. It is generally assumed that, in the absence of direct visual contact, such species are less vulnerable to disturbance. Seabird colonies can support large populations of burrow- and cavity-nesting species and attract increasing numbers of tourists. We investigated the potential effects of recreational disturbance on the reproductive behaviour of the European storm petrel Hydrobates pelagicus, a nocturnally-active cavity-nesting seabird. Reproductive phenology and outcome of nests subject to high and low levels of visitor pressure were recorded in two consecutive years. Hatching success did not differ between disturbance levels, but overall nestling mortality was significantly higher in areas exposed to high visitor pressure. Although visitor numbers were consistent throughout the season, the magnitude and rate of a seasonal decline in productivity were significantly greater in nests subject to high disturbance. This study presents good evidence that, even when humans do not pose a direct mortality risk, animals may perceive them as a predation risk. This has implications for the conservation and management of a diverse range of burrow- and cavity-dwelling animals. Despite this reduction in individual fitness...

An assessment of natural and human disturbance effects on Mexican ecosystems: current trends and research gaps

Calderon-Aguilera, Luis E.; Rivera-Monroy, Vıctor H.; Porter-Bolland, Luciana; Martinez-Yrizar, Angelina; Ladah, Lydia B.; Martinez-Ramos, Miguel; Alcocer, Javier; Santiago-Perez, Ana Luisa; Hernandez-Arana, Hector A.; Reyes-Gomez, Victor M.; Perez-Salic
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.29%
Mexico harbors more than 10% of the planet’s endemic species. However, the integrity and biodiversity of many ecosystems is experiencing rapid transformation under the influence of a wide array of human and natural disturbances. In order to disentangle the effects of human and natural disturbance regimes at different spatial and temporal scales, we selected six terrestrial (temperate montane forests, montane cloud forests, tropical rain forests, tropical semi-deciduous forests, tropical dry forests, and deserts) and four aquatic (coral reefs, mangrove forests, kelp forests and saline lakes) ecosystems. We used semiquantitative statistical methods to assess (1) the most important agents of disturbance affecting the ecosystems, (2) the vulnerability of each ecosystem to anthropogenic and natural disturbance, and (3) the differences in ecosystem disturbance regimes and their resilience. Our analysis indicates a significant variation in ecological responses, recovery capacity, and resilience among ecosystems. The constant and widespread presence of human impacts on both terrestrial and aquatic ecosystems is reflected either in reduced area coverage for most systems, or reduced productivity and biodiversity, particularly in the case of fragile ecosystems (e.g....

Human-driven Benthic Jellyfish Blooms: Causes and Consequences for Coastal Marine Ecosystems

Stoner, Elizabeth W
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
Relevância na Pesquisa
46.05%
Coastal marine ecosystems are among the most impacted globally, attributable to individual and cumulative effects of human disturbance. Anthropogenic nutrient loading is one stressor that commonly affects nearshore ecosystems, including seagrass beds, and has positive and negative effects on the structure and function of coastal systems. An additional, previously unexplored mechanistic pathway through which nutrients may indirectly influence nearshore systems is by driving blooms of benthic jellyfish. My dissertation research, conducted on Abaco Island, Bahamas, focused on elucidating the role that benthic jellyfish have in structuring systems in which they are common (i.e., seagrass beds), and explored mechanistic processes that may drive blooms of this taxa. To establish that human disturbances (e.g., elevated nutrient availability) may drive increased abundance and size of benthic jellyfish, Cassiopea spp., I conducted surveys in human-impacted and unimpacted coastal sites. Jellyfish were more abundant (and larger) from human-impacted areas, positively correlated to elevated nutrient availability. In order to elucidate mechanisms linking Cassiopea spp. with elevated nutrients, I evaluated whether zooxanthellae from Cassiopea were higher from human-disturbed systems...

Multiple spatial-scale resource selection function models in relation to human disturbance for moose in northeastern China

Jiang, G.; Ma, J.; Zhang, M.; Stott, P.
Fonte: Blackwell Science Asia Publicador: Blackwell Science Asia
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
46.07%
he moose (Alces alces cameloides) population in northeastern China is on the southernmost edge of its distribution in Asia. A survey was conducted to determine moose resource selection and the effects of human disturbance on moose in a study area of 20,661 ha located on the northwestern slope of the Lesser Khingan Mountains, located in northeastern China. Predictive models of resource selection were developed using logistic and autologistic regression. All models considered resource variable selection at two spatial scales, patch and landscape. At the patch scale, moose preferred larger birch (Betula platyphylla) patches, but avoided larger tamarack (Larix gmelinii) patches. At the landscape scale, moose preferred higher densities of tamarack patches, i.e., heterogeneity of tamarack stands, selected areas with more abundant annual shoots, terrain conducive to better concealment, higher altitudes and areas saturated with soil moisture. Roads and forest harvest intervals were identified as important human disturbance factors. This is the first time that moose have been reported to avoid roads, and the avoidance distance was nearly 3 km. We believe that in this region moose under the influence of roads are behaviorally plastic, compared with the indifference of moose to the presence of roads in other regions. Moose avoided forest areas logged more than 3 years previously and preferred areas logged 1–2 years previously. In addition...

Effects of human activities on the spatial distribution of eastern roe deer Capreolus pygargus bedfordi in the Lesser Khingan Mountains, northeastern China

Jiang, G.; Ma, J.; Zhang, M.; Stott, P.
Fonte: Polish Acad Sciences Publicador: Polish Acad Sciences
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
46.2%
Eastern roe deer Capreolus pygargus bedfordi Thomas, 1908 occurred throughout China historically, but today are only found in 7 provinces . Their populations in China have been greatly impacted by human disturbances. Little is known about what kinds of human disturbances impact their distribution and resource requirements for survival. A survey was conducted over 20 661 ha located at the Erkehe Forestry Farm in the Lesser Khingan Mountains, northeastern China. Field work lasted from January to March, 2006 and January to March, 2007, and a total of 613 plots were visited along 28 sampling transects. Predictive models of easter roe deer resource selection were developed with or without the inclusion of human disturbance factors. Whether human disturbance exists or not, eastern roe deer retained strong links to patch size and patch density of low shrub and swamp, and the probability of moose occurrence. Low shrub and swamps created after logging provide more abundant annual shoots for food, and were vital for survival in harsh winters. When human disturbance was not modeled, eastern roe deer avoided higher density of both Betula platyphylla and Larix gmelinii patches at a landscape scale, and larger mixed coniferous and broad-leaf patchs at local scales. Once human disturbances existed...

Natural and anthropogenic influence on soil erosion in a rural watershed in the Brazilian southeastern region

Sobral, Anahi Chimini; Palcheco Peixoto, Anna Silvia; Nascimento, Victor Fernandez; Rodgers, John; Silva, Alexandre Marco da
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 709-720
Português
Relevância na Pesquisa
46.09%
Human activities have been driven land cover, provoking acceleration of the erosive process and alteration on the soil characteristics. To explore the effects of human disturbance, we investigated the influences of natural and anthropogenic features on soil quality and soil erosion indicators (EI) within a Brazilian rural watershed located in Bauru Municipality, State of So Paulo. A pre-established set of soil EI was used to evaluate the influence of anthropogenic land cover categories on the presence and severity of erosion, related with spatial variations of soil attributes. On-site visits were carried out to measure the occurrence and the intensity of eleven separate EI values and to collect undisturbed topsoil samples for subsequent analyses. We registered 17 occurrences of EIs, distributed in ten locals. Occurrence and intensity of EIs were related to degree of sheet erosion. The EI qualities were more strongly associated with land cover management practices than to local topographic features. The occurrence of EIs and characteristics of soil and soil organic matter (SOM) were not significantly self-correlated. Although land cover class seems to influence soil properties and SOM attributes, we observed that the granulometric composition of the soils also contributes to the structural characteristics of the soil and consequently to the dynamic loss and gain of soil carbon. Sites covered with natural remnant vegetation (NRV) store 96.5 Mg ha(-1) of C and grassy and tilled soils stored more C than NRV...

The differential influences of human-induced disturbances on tree regeneration community: a landscape approach

Zamorano Elgueta, Carlos; Cayuela Delgado, Luis; Rey Benayas, José María; Donoso, Pablo J.; Geneletti, Davide; Hobbs, Richard J.
Fonte: Ecological Society of America Publicador: Ecological Society of America
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
Relevância na Pesquisa
46.22%
Understanding the processes shaping biological communities under interacting disturbances is a core challenge in ecology. Although the impacts of human-induced disturbances on forest ecosystems have been extensively studied, less attention has been paid to understanding how tree regeneration at the community level responds to such disturbances. Moreover, these previous studies have not considered how these effects change according to major social and environmental factors that can influence forest use at a landscape scale. In this study, we investigate the effects of cattle grazing and selective logging on the composition of tree regeneration communities in relation to forest successional stage and land tenure regime in Chilean temperate forests, a global biodiversity hotspot. We recorded seedlings, saplings and basal area of stumps of tree species (as a surrogate for selective logging), and number of cattle dung pats (as a surrogate for cattle pressure) in 129 25 3 20 m plots in small (,200 ha) and large properties in different successional stages (old-growth, intermediate, secondary forests). The regeneration of the ten more abundant species as predicted by human disturbance, land tenure, forest successional stage, and number of parent trees was modelled using generalised linear models. Predictions for each individual model were made under different scenarios of human disturbance. The predicted regeneration results were assembled and subjected to ordination analyses and permutation multivariate analyses of variance to determine differences in regeneration composition under each scenario. In most cases...

Efectos del disturbio humano sobre una colonia mixta de aves marinas en Patagonia; Effects of human disturbance on a mixed-species seabird colony in Patagonia

Yorio, Pablo; Quintana, Flavio
Fonte: Aves Argentinas / Asociación Ornitológica del Plata Publicador: Aves Argentinas / Asociación Ornitológica del Plata
Tipo: info:eu-repo/semantics/article; artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em /10/1996 Português
Relevância na Pesquisa
56.18%
Conocer la sensibilidad de las especies al disturbio humano puede ayudar en la evaluación del impacto sobre las colonias de aves marinas. Durante 1989 a 1991 evaluamos la respuesta a la presencia humana, de 5 especies de aves marinas en la colonia mixta de Punta León, recientemente propuesta como reserva turística. La distancia a la cual los Cormoranes Imperiales (Phalacrocorax atriceps) comenzaron a responder a los acercamientos decreció a lo largo de la estación reproductiva (l00 a 6.6 m). El abandono de nidos periféricos ocurrió en todos los acercamientos a menos de 8 m y afectó exclusivamente la sección próxima al disturbio. Los huevos expuestos fueron predados por Gaviotas Cocineras (Larus dominicanus). Durante el asentamiento, algunos Biguás (Phalacrocorax olivaceus) abandonaron sus nidos cuando nos aproximamos a menos de 25 m, mientras que durante la incubación, los comportamientos de alerta ocurrieron a distancias menores de 20 m. Las distancias a las cuales las Gaviotas Cocineras levantaron vuelo en respuesta a la presencia humana, disminuyeron a medida que avanzó la temporada (>100 a 6.7 m). Durante los acercamientos a la colonia de Gaviotines Reales (Sterna maxima) y Pico Amarillo (S. eurygnatha), tanto los individuos que se estaban asentando como los que estaban incubando en la periferia...

Dispersión de semillas de pindó (Syagrus romanzoffiana) en la Selva Paranaense: efectos ecológicos y genéticos de la interacción con su principal dispersor y del disturbio humano del hábitat; Seed dispersal of pindó (Syagrus romanzoffiana) in the Paranaense Forest: ecological and genetic effects of the interaction with its main disperser and of human-induced habitat disturbance

Giombini, Mariano Ignacio
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2013 Português
Relevância na Pesquisa
46.09%
La dispersión de semillas es un proceso de enorme relevancia para la ecología y evolución de las comunidades jugando un papel determinante sobre la regeneración y el flujo genético de las plantas. En los bosques tropicales y subtropicales la mayoría de las plantas son dispersadas por animales. El disturbio del hábitat frecuentemente implica la defaunación y la consecuente desaparición de las interacciones planta-animal. La Selva Paranaense ha sido reducida a menos del 8% de su extensión original. Nuestro objetivo general fue evaluar posibles efectos ecológicos y genéticos de la defaunación para especies dispersadas por vertebrados. En particular, estudiamos algunos aspectos de la dispersión de semillas de la palmera pindó (Syagrus romanzoffiana), una especie clave como fuente de alimento para la comunidad de frugívoros en la Selva Paranaense. El pindó mostró una alta dominancia entre los frutos consumidos por el tapir en el Parque Nacional Iguazú, y un alto nivel de reclutamiento de juveniles fue hallado en las letrinas generadas por este frugívoro. El reclutamiento fue mayor en las letrinas que debajo de la copa de palmeras adultas y sitios al azar dentro del Parque. Para estudiar los efectos genéticos de la dispersión de semillas por tapires y de la defaunación transferimos microsatélites a pindó de otras especies de palmera...

Efectos del disturbio humano sobre una colonia mixta de aves marinas en Patagonia; Effects of human disturbance on a mixed-species seabird colony in Patagonia

Yorio, Pablo; Quintana, Flavio
Fonte: Revista de Ornitología Neotropical; Aves Argentinas; Aves Argentinas / Asociación Ornitológica del Plata Publicador: Revista de Ornitología Neotropical; Aves Argentinas; Aves Argentinas / Asociación Ornitológica del Plata
Tipo: info:eu-repo/semantics/article; artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em /10/1996 Português
Relevância na Pesquisa
56.18%
Conocer la sensibilidad de las especies al disturbio humano puede ayudar en la evaluación del impacto sobre las colonias de aves marinas. Durante 1989 a 1991 evaluamos la respuesta a la presencia humana, de 5 especies de aves marinas en la colonia mixta de Punta León, recientemente propuesta como reserva turística. La distancia a la cual los Cormoranes Imperiales (Phalacrocorax atriceps) comenzaron a responder a los acercamientos decreció a lo largo de la estación reproductiva (l00 a 6.6 m). El abandono de nidos periféricos ocurrió en todos los acercamientos a menos de 8 m y afectó exclusivamente la sección próxima al disturbio. Los huevos expuestos fueron predados por Gaviotas Cocineras (Larus dominicanus). Durante el asentamiento, algunos Biguás (Phalacrocorax olivaceus) abandonaron sus nidos cuando nos aproximamos a menos de 25 m, mientras que durante la incubación, los comportamientos de alerta ocurrieron a distancias menores de 20 m. Las distancias a las cuales las Gaviotas Cocineras levantaron vuelo en respuesta a la presencia humana, disminuyeron a medida que avanzó la temporada (>100 a 6.7 m). Durante los acercamientos a la colonia de Gaviotines Reales (Sterna maxima) y Pico Amarillo (S. eurygnatha), tanto los individuos que se estaban asentando como los que estaban incubando en la periferia...

Congruence between natural and human forest disturbance: a case study from Australian montane ash forest

Lindenmayer, David; McCarthy, Michael
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.24%
We examined the hypothesis that the impacts of human disturbances like logging on forest biodiversity will be minimised if there is close congruence with the effects of natural disturbances (e.g. wildfire). The montane ash forests of the Central Highlands of Victoria (south-eastern Australia) are used as a case study to examine several themes associated with congruence between natural (wildfire) and human disturbance (clearfell logging) regimes. These themes include: (1) the types of biological legacies left or created following wildfires and their use as habitat components by vertebrates, (2) the use of biological legacies to reconstruct pre-European stand structural conditions, (3) contrasts between stand and landscape conditions created by wildfire and clearfelling, and (4) approaches to create greater consistency between the effects of wildfire and logging at the stand and landscape levels. Extensive empirical studies reveal major differences between clearfelled forests and those burned by wildfires, particularly with respect to vegetation structure, plant species composition, and landscape patchiness. Clearfelling simplifies stand structure and creates a single cohort of regrowth trees. In contrast, natural disturbance by wildfire varies in its intensity and has variable effects - all trees are killed in some stands and large dead trees remain. In others a multi-aged stand develops which is a mixture of fire-damaged living and dead trees. Many of the biological legacies typical of stands damaged by wildfires are also those which are severely depleted in young clearfelled forest. Differences between burned and clearfelled forests can have significant negative impacts for many forest-dependent vertebrates. The widespread application of clearfelling operations is not consistent with the effects of natural disturbance regimes. This suggests there is a need to change cutting and regeneration methods to more closely resemble natural disturbance regimes and promote structural complexity in stands of harvested forest to enhance their value for wildlife. Such changed silvicultural systems should lead to: (1) the retention of more living and dead trees that remain standing through several cutting events and eventually develop cavities...

Effects of human disturbance on a burrow nesting seabird

Albores-Barajas,Yuri V.; Soldatini,Cecilia
Fonte: Instituto de Biología Publicador: Instituto de Biología
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 Português
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56.19%
During 2004, we followed 72 natural burrows to determine the effects of disturbance on breeding success of Cassin's auklets (Ptychoramphus aleuticus). We used distance from a human settlement or path in the analysis of disturbance. Birds whose burrows were closer to the path or the village had a higher rate of nest abandonment and lower breeding success compared to birds nesting further away from the path or the village. Also, older and more experienced individuals represented a larger proportion of the breeding population on less disturbed areas than on highly disturbed ones, probably as older individuals tend to arrive earlier at the breeding grounds, and failed breeders may change burrow sites to move away from disturbance. P. aleuticus are adversely affected by human activity at colonies even if birds are not handled and burrows are not opened, and this has implications for conservation, and planning of ecotourism. On the long term, this can have negative consequences for this species and others with similar characteristics.