نتایج جستجو برای: national parks

تعداد نتایج: 399103  

Journal: :Risk analysis : an official publication of the Society for Risk Analysis 2008
Bonita L McFarlane David O T Watson

Western Canada is experiencing an unprecedented outbreak of the mountain pine beetle (MPB). The MPB has the potential to impact some of Canada's national parks by affecting park ecosystems and the visitor experience. Controls have been initiated in some parks to lessen the impacts and to prevent the beetle from spreading beyond park boundaries. We examine the perception of ecological risk assoc...

2003
Alexander Almer Herwig Zeiner Christian Derler Harald Stelzl Patrick Luley

The tourism in rural areas and national parks can be regarded as a very sensitive economic factor. On the one hand eco-tourism regions and especially national parks have to present their natural environment and fascinate landscape. On the other hand they have to guide tourist streams to avoid negative effects on their assets. This paper will briefly discuss the current situation of the digital ...

Journal: :محیط زیست طبیعی 0
شیرکو جعفری دانشجوی کارشناسی ارشد محیط زیست، دانشکدۀ منابع طبیعی، دانشگاه تهران، ایران، کرج افشین علیزاده شعبانی استادیار دانشکده منابع طبیعی، دانشگاه تهران، ایران، کرج افشین دانه کار دانشیار دانشکده منابع طبیعی، دانشگاه تهران، ایران، کرج علی اکبر نظری سامانی استادیار دانشکده منابع طبیعی، دانشگاه تهران، ایران، کرج

internationally, one of the most important purposes to establish a national park is to protect a unique ecosystem with all its inclusive biota. therefore, this will facilitate the management and protection of the neighboring lands. unfortunately, this trend was reversed in iranian national parks. during recent decades, the land cover changes in protected areas have led to the decrease of the re...

2013
R. A. Ellis D. J. Jacob

National parks in the United States are protected areas wherein the natural habitat is to be conserved for future generations. Deposition of anthropogenic nitrogen (N) transported from areas of human activity (fuel combustion, agriculture) may affect these natural habitats if it exceeds an ecosystem-dependent critical load (CL). We quantify and interpret the deposition to Class I US national pa...

Journal: :Environmental management 2014
Sandra Sotomayor Carla Barbieri Sonja Wilhelm Stanis Francisco X Aguilar Jordan W Smith

This study explores the importance of different motivations to visit three types of recreational settings--farms, private forests, and state or national parks. Data were collected via a mail-back questionnaire administered to a stratified random sample of households in Missouri (USA). Descriptive and inferential statistics reveal both similarities and discontinuities in motivations for visiting...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2008
Oliver R W Pergams Patricia A Zaradic

After 50 years of steady increase, per capita visits to U.S. National Parks have declined since 1987. To evaluate whether we are seeing a fundamental shift away from people's interest in nature, we tested for similar longitudinal declines in 16 time series representing four classes of nature participation variables: (i) visitation to various types of public lands in the U.S. and National Parks ...

Journal: :eco.mont (Journal on Protected Mountain Areas Research) 2017

Journal: :Michigan Law Review 1981

Journal: :Nonprofit and Voluntary Sector Quarterly 2016

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