Ecology is the study of a community of biota, including the interactions with abiotic factors such as soils, water, and meteorological factors. The field of ecology addresses interactions of plants and animals including feeding behavior, selection of nesting or denning sites and competition among species. Time changes are particularly important, such as landscape changes arising from plant succession. Conservation of habitats is analyzed in order to determine the viability of not only individual species, but of the entire assemblage of flora, fauna and micro-organisms in a given ecosystem.
The Cheetah, Acinonyx jubatus, is a vulnerable species within the cat family. While the fastest land animal and an adept hunter, this felid is not agressive...
PopulationLast Updated on 2014-11-20 11:53:49Population is the study of the character, number, and distribution of living organisms residing in or migrating through particular places. The study of populations is a quantifiable foundation for concepts in sociology, ecology, genetics and evolution by means of natural selection. Study of population is closely associated with social and biological sciences and it examines the relative size of a breeding group with respect to the age structure, number of viable offspring, survival rates, and longevity among separate aggregations. Human demography, as a branch of sociology, is the study of the attributes of and changes in the aggregate number of people residing in particular communities around the world and their causes.
On August 1, 2010, the U.S. Census Bureau estimated the Earth's human population at over 6.859 billion people. It grew at an estimated rate... More »
Ecosystems and Human Well-Being: Volume 1: Current State and Trends: Air Quality and ClimateLast Updated on 2014-11-17 12:15:25
This is Chapter 13 of the Millenium Ecosystem Assessment report Ecosystems and Human Well-Being: Volume 1: Current State and Trends
Coordinating Lead Authors: Jo House, Victor Brovkin
Lead Authors: Richard Betts, Bob Constanza, Maria Assunçao Silva Dias, Beth Holland, Corinne Le Quéré, Nophea Kim Phat, Ulf Riebesell, Mary Scholes
Contributing Authors: Almut Arneth, Damian Barratt, Ken Cassman, Torben Christensen, Sarah Cornell, Jon Foley, Laurens Ganzeveld, Thomas Hickler, Sander Houweling, Marko Scholze, Fortunat Joos, Karen Kohfeld, Manfredi Manizza, Denis Ojima, I. Colin Prentice, Crystal Schaaf, Ben Smith, Ina Tegen, Kirsten Thonicke, Nicola Warwick
Review Editors: Pavel Kabat, Shuzo Nishioka
Ecosystems, both natural and managed, exert a strong influence on climate and air quality. Ecosystems are both sources and sinks of greenhouse gases,... More »
Species richnessLast Updated on 2014-11-09 19:13:40Species richness is simply the number of species present in a sample, community, or taxonomic group. Species richness is one component of the concept of species diversity, which also incorporates evenness, that is, the relative abundance of species. Species diversity is one component of the broader concept of biodiversity. About 1.75 million living species and 300,000 fossil species have been described by scientists. Estimates of the total species richness of the Earth range from three to 10 million, with some estimates as high as 50 million.
Patterns of species richness can be observed at a variety of levels. The causes of these patterns remain active areas of research in ecology, biogeography, and evolutionary biology.
Some taxonomic groups of organisms have more species than other groups. For example, there are almost three times more species of beetles (Order Coleoptera) than... More »
Species range limitsLast Updated on 2014-11-09 18:49:44Species range limits (SRLs) are defined as the spatial boundaries beyond which no living individuals of a given species occur. Populations occurring near or at SRLs are often referred to as “marginal,” “peripheral,” “edge,” or “border” populations. SRLs may represent areas beyond which individuals cannot physiologically tolerate ecological conditions or areas where they have not yet dispersed. SRLs may be stable (i.e., at equilibrium) or may represent areas where range expansion through migration or population growth is in the process of occurring. SRLs are significant to ecology, evolution, and conservation for several reasons. They provide opportunities to understand the conditions under which populations expand or contract, and the conditions under which populations may evolve new forms. Additionally, SRLs... More »
Biological diversity in the HimalayasLast Updated on 2014-11-04 11:46:06
Stretching in an arc over 3,000 kilometers of northern Pakistan, Nepal, Bhutan and the northwestern and northeastern states of India, the Himalaya hotspot includes all of the world's mountain peaks higher than 8,000 meters. This includes the world's highest mountain, Sagarmatha (Mt. Everest) as well as several of the world's deepest river gorges.
This immense mountain range, which covers nearly 750,000 km2, has been divided into two regions: the Eastern Himalaya, which covers parts of Nepal, Bhutan, the northeast Indian states of West Bengal, Sikkim, Assam, and Arunachal Pradesh, southeast Tibet (China), and northern Myanmar; and the Western Himalaya, covering the Kumaon-Garhwal, northwest Kashmir, and northern Pakistan. While these divisions are largely artificial, the deep defile carved by the antecedent Kali Gandaki River between the Annapurna and Dhaulagiri... More »
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