Résultats de la recherche | Land Portal

Résultats de la recherche

Showing items 1 through 9 of 47.
  1. Library Resource
    Articles et Livres
    décembre, 2006
    Chine

    Since China's economic reform in the late 1970s, Shanghai, the country's largest and most modern city, has experienced rapid expansion and urbanization. Here, we explore its land‐use and land‐cover changes, focusing on the impacts of the urbanization process on air and water quality, local climate, and biodiversity. Over the past 30 years, Shanghai's urban area and green land (eg urban parks, street trees, lawns) have increased dramatically, at the expense of cropland.

  2. Library Resource
    Articles et Livres
    décembre, 1991

    Ecological risk assessments are used by policy makers and regulatory agencies for balancing and comparing ecological risks associated with environmental hazards. An approach for regional—scale ecological risk assessment is described and demonstrated by modeling environmental risks associated with elevated ozone in a forested region. The demonstration illustrates (1) how a regional—scale risk assessment might be done, (2) the importance of spatial characteristics in considering regional—scale risk, and (3) the necessity of considering terrestrial and aquatic linkages.

  3. Library Resource
    Articles et Livres
    décembre, 2009

    The opportunity exists to improve intensively managed landscapes (urban and agricultural areas dominated by human activities) through greater engagement of ecologists in the process of ecological landscape design. This approach encourages exploration of multifunctional solutions to meet the needs of growing populations in many areas around the world, while minimizing the negative impacts of human activities on the environment. This is achieved by incorporating theoretical and applied principles from the fields of landscape ecology, agroecology, and ecological design.

  4. Library Resource
    Articles et Livres
    décembre, 2012

    As natural resource management and conservation goals expand and evolve, practitioners and policy makers are increasingly seeking options that optimize benefits among multiple, often contradictory objectives. Here, we describe a simple approach for quantifying the consequences of alternative management options in terms of benefits and trade‐offs among multiple objectives.

  5. Library Resource
    Articles et Livres
    décembre, 2014
    Suisse

    The installation of green roofs, defined here as rooftops with a shallow soil cover and extensive vegetation, has been proposed as a possible measure to mitigate the loss of green space caused by the steady growth of cities. However, the effectiveness of green roofs in supporting arthropod communities, and the extent to which they facilitate connectivity of these communities within the urban environment is currently largely unknown.

  6. Library Resource
    Articles et Livres
    décembre, 2010

    Many carbon dioxide (CO₂) emission‐reduction strategies currently under consideration rely on terrestrial carbon (C) sequestration to offset substantial proportions of CO₂ emissions. We estimated C sequestration rates and potential land areas for a diverse array of land‐cover changes in the Upper Midwest of the US, a “best case” region for this study because of its relatively modest CO₂ emissions and the large areas of cropland potentially available for conversion.

  7. Library Resource
    Articles et Livres
    décembre, 2010
    États-Unis d'Amérique

    What landscapes best represent the land uses and land covers (LU/LC) of the continental United States? Would the set include a cornfield? A forest? A backyard? Combining principles of landscape ecology and computer science, we identified a small set of “exemplar landscapes”, representing distinct LU/LC pattern types of the conterminous US. We first partitioned the 1992 US National Land Cover Dataset into 193 705 landscapes, and quantified patterns with standard measures of LU/LC composition and configuration.

  8. Library Resource
    Articles et Livres
    décembre, 2015

    Spatiotemporal variation in demographic rates can have profound effects for population persistence, especially for dispersal‐limited species living in fragmented landscapes. Long‐term studies of plants in such habitats help with understanding the impacts of fragmentation on population persistence but such studies are rare. In this work, we reanalyzed demographic data from seven years of the short‐lived cactus Opuntia macrorhiza var. macrorhiza at five plots in Boulder, Colorado.

  9. Library Resource
    Articles et Livres
    décembre, 2013
    Amérique septentrionale

    Whether ignited by lightning or by Native Americans, fire once shaped many North American ecosystems. Euro–American settlement and 20th‐century fire suppression practices drastically altered historic fire regimes, leading to excessive fuel accumulation and uncharacteristically severe wildfires in some areas and diminished flammability resulting from shifts to more fire‐sensitive forest species in others. Prescribed fire is a valuable tool for fuel management and ecosystem restoration, but the practice is fraught with controversy and uncertainty.

  10. Library Resource
    Articles et Livres
    décembre, 2013
    Afrique du Sud, Afrique, Afrique australe

    Socioecological theory, developed through the study of urban environments, has recently led to a proliferation of research focusing on comparative analyses of cities. This research emphasis has been concentrated in the more developed countries of the Northern Hemisphere (often referred to as the “Global North”), yet urbanization is now occurring mostly in the developing world, with the fastest rates of growth in sub‐Saharan Africa.

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