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ECOSYSTEMS DEFINITION

Types of Ecosystems

[ Oceans | Deserts | Grasslands | Polar Regions | Wetlands | Mountains | Forests | Cities ]

 

An ecosystem consists of a dynamic set of living organisms (plants, animals and microorganisms) all interacting among themselves and with the environment in which they live (soil, climate, water and light).

An ecosystem does not have precise boundaries - it can be as small as a pond or a dead tree, or as large as the Earth itself. An ecosystem can also be defined in terms of its vegetation, animal species or type of relief, for example.

The major ecosystems are generally described as:

  • Aquatic ecosystems - saltwater or freshwater ecosystems;
  • Terrestrial ecosystems - forests, prairies, deserts, etc.

Forest ecosystems are characterized by predominance of trees, and by the fauna, flora and ecological cycles (energy, water, carbon and nutrients) with which they are closely associated.

Ecosystems vary in size. They can be as small as a puddle or as large as the Earth itself. Any group of living and nonliving things interacting with each other can be considered as an ecosystem.

Source: Canadian Forest Service

 

HOTSPOTS DEFINED

A seminal paper by Norman Myers in 1988 first identified ten tropical forest “hotspots” characterized both by exceptional levels of plant endemism and by serious levels of habitat loss. In 1990 Myers added a further eight hotspots, including four Mediterranean-type ecosystems. Conservation International adopted Myers’ hotspots as its institutional blueprint in 1989, and in 1996, the organization made the decision to undertake a reassessment of the hotspots concept, including an examination of whether key areas had been overlooked. Three years later an extensive global review was undertaken, which introduced quantitative thresholds for the designation of biodiversity hotspots:

To qualify as a hotspot, a region must meet two strict criteria: it must contain at least 1,500 species of vascular plants (> 0.5 percent of the world’s total) as endemics, and it has to have lost at least 70 percent of its original habitat.

In the 1999 analysis, published in the book Hotspots: Earth’s Biologically Richest and Most Endangered Terrestrial Ecoregions, and a year later in the scientific journal Nature (Myers, et al. 2000), 25 biodiversity hotspots were identified. Collectively, these areas held as endemics no less than 44 percent of the world’s plants and 35 percent of terrestrial vertebrates in an area that formerly covered only 11.8 percent of the planet’s land surface. The habitat extent of this land area had been reduced by 87.8 percent of its original extent, such that this wealth of biodiversity was restricted to only 1.4 percent of Earth’s land surface.

A second major reanalysis has now been undertaken and published in the book Hotspots Revisited. This website has been completely updated with the results of this analysis, and details of this study can be found in the sections of the website Hotspots Revisited and Key Findings.

HOTSPOTS IN CONTEXT | IMPACT OF HOTSPOTS | HOTSPOTS REVISITED
KEY FINDINGS | HOTSPOTS IN PERIL | CONSERVATION RESPONSES

United Nations Environment Programme
United Nations Environment Programme

 

 

 

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