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Urban water governance
Published in Thomas Bolognesi, Francisco Silva Pinto, Megan Farrelly, Routledge Handbook of Urban Water Governance, 2023
Thomas Bolognesi, Megan Farrelly, Francisco Silva Pinto
The high human density in urban areas stresses carrying capacity, i.e., the ability of an environment to sustain its population size. Urban ecological footprint indicators aim at measuring the extent to which human pressures affect carrying capacity. Such indicators compare the city surface to the land surface theoretically required to support its population. The discrepancy is sizeable. For instance, Rees and Wackernagel (1996) estimated that the ecological footprint of Vancouver in 1991 was 180 times larger than its administrative size. As per capita urban ecological footprint tends to be greater than per capita national ecological footprint, urbanisation poses severe sustainability challenges (Ortega-Montoya and Johari 2020). Consequently, more and more research focuses on the factors favouring the introduction of sustainability measures in the policy agendas of cities (Reckien et al. 2018; Swann and Deslatte 2018).
Biodiversity: Habitat Suitability
Published in Yeqiao Wang, Terrestrial Ecosystems and Biodiversity, 2020
In general, the fitness of a population is the number of births per generation (or birth rate) minus the number of deaths per generation (death rate).[2] Furthermore, a population is in suitable habitat only if the environment can support the population (e.g., the population sustains itself and is able to maintain its population size). The fitness of the population must, therefore, be greater than (birth rate greater than death rate) or equal to zero. If we were to look at a species existing in a habitat of optimal quality, we would expect to observe two possible fitness responses.[3] First, if the population is at equilibrium—perhaps this population has existed for several generations in this optimal habitat—the birth rate would be equal to the death rate. This population is said to be at carrying capacity, the largest population size the habitat can support with given levels of resources. Alternatively, if the population has not reached carrying capacity and the birth rate is higher than the death rate, the population size would be increasing. Species, however, do not exist only in optimal habitats (for reasons we will discuss later). Species can be found in a range of habitats of varying quality, which would result in varying levels of fitness.[4] To define habitat suitability, we need to quantify the relationship between fitness and the habitat of a particular area.
Human Health Risk Assessment
Published in Lorris G. Cockerham, Barbara S. Shane, Basic Environmental Toxicology, 2019
Ecotoxicity assessments are considerably more complex than the human health assessments due to the need to consider the effects of the hazardous materials on a community of many different species of organisms rather than on only one as is the case for the human assessment. The ecotoxic effects may affect various species differently so there may be a reduction in population size for certain species and changes in the community structure of the ecosystem. Ideally, data from studies of the hazardous substances present in the hazardous waste site on the ecosystem in or around the hazardous waste site would be ideal for the ecotoxicity evaluation. Normally, however, ecotoxicologists study the effects of a single substance on specific populations of one species. In addition, it may be necessary to use data from one species to predict the toxic effects for several species. The data used for the ecotoxicity evaluation should be based on species that are representative or good indicators for the indigenous species.
The perceived relationship between population growth and current ecological problems using repertory grid technique
Published in Human and Ecological Risk Assessment: An International Journal, 2019
Population growth (PG) is one of the main drivers of environmental deterioration (Ehrlich and Holdren 1971; Oskamp 2000; Swim et al.2011). The mounting ecological consequences caused by steady demographic expansion include air and water pollution, soil deterioration, accelerated extinction of biodiversity, climate change and destruction of other interdependent ecosystems that sustain life (Bandura 2002; UNEP, 2005). In fact, it is difficult to think of a single environmental problem that is not directly or indirectly related to an increase in population size or density. Beck and Kolankiewicz (2000) review some of the world's greatest scientists and conservationists, who warn against the threat of PG on human survival. Wilson (1999), the noted Harvard biologist wrote: “The raging monster upon the land is population growth. In its presence, sustainability is but a fragile theoretical concept.” (p. 328). Rees (2014), the originator of the “ecological footprint” concept, wrote: “On a planet already in overshoot, there is no possibility of raising even the present world population” (p. 3).