162 resultados para Ecological indicators


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Body size determines a host of species traits that can affect the structure and dynamics of food webs, and other ecological networks, across multiple scales of organization. Measuring body size provides a relatively simple means of encapsulating and condensing a large amount of the biological information embedded within an ecological network. Recently, important advances have been made by incorporating body size into theoretical models that explore food web stability, the patterning of energy fluxes, and responses to perturbations. Because metabolic constraints underpin bodysize scaling relationships, metabolic theory offers a potentially useful new framework within which to develop novel models to describe the structure and functioning of ecological networks and to assess the probable consequences of biodiversity change.

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Sustainable development comprises of three dimensions. The three dimensions are the environment, the social and the economic. There have been many indicators used to measure the three dimensions of sustainability. For example air pollution, consumption of natural resources, quality of open space, noise, equity and opportunities and economic benefits from transport and land use. Urban areas constitute the most crucial factor in the sustainability. Urban systems affect and are affected by natural systems beyond their physical boundaries and in general the interdependence between the urban system and the regional and global environment is not reflected in urban decision making. The use of energy in the urban system constitutes the major element in the construction and function of urban areas. Energy impacts across the boundaries of the three dimensions of sustainability. The objective of this research is to apply energy-use-indicators to the urban system as a measure of sustainability. This methodology is applied to a case study in the United Kingdom.

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Ecological stability is touted as a complex and multifaceted concept, including components such as variability, resistance, resilience, persistence and robustness. Even though a complete appreciation of the effects of perturbations on ecosystems requires the simultaneous measurement of these multiple components of stability, most ecological research has focused on one or a few of those components analysed in isolation. Here, we present a new view of ecological stability that recognises explicitly the non-independence of components of stability. This provides an approach for simplifying the concept of stability. We illustrate the concept and approach using results from a field experiment, and show that the effective dimensionality of ecological stability is considerably lower than if the various components of stability were unrelated. However, strong perturbations can modify, and even decouple, relationships among individual components of stability. Thus, perturbations not only increase the dimensionality of stability but they can also alter the relationships among components of stability in different ways. Studies that focus on single forms of stability in isolation therefore risk underestimating significantly the potential of perturbations to destabilise ecosystems. In contrast, application of the multidimensional stability framework that we propose gives a far richer understanding of how communities respond to perturbations.