Ecologists remap the biosphere to include humans
ESA ecologists have released a new map of the biosphere based on global patterns of ecosystem form and process created by humans- a 21st century challenge to the now classic biome maps that appear in nearly every ecology textbook. [See the article in Frontiers in Ecology and the Environment, available at http://www.ecotope.org/people/ellis/papers/ellis_2008.pdf.] Global data from satellites and land management statistics were used to map a new system of “anthropogenic biomes”, “anthromes”, or “human biomes” that describe the biosphere as it exists today, the result of human reshaping of ecosystems.Results demonstrate that less than 20% of Earth’s ice-free land is wild, and only 20% of this is forests; more than 36% is barren, such that Earth’s remaining wildlands account for only about 10% of global net primary production. Anthropogenic biomes are not simple vegetation categories, and are best characterized as heterogeneous landscape mosaics combining a variety of different land uses and land covers. Urban areas are embedded within agricultural land, trees are interspersed with croplands and housing, and managed vegetation is mixed with semi-natural vegetation (e.g. croplands are embedded within rangelands and forests). For example, Croplands biomes are mostly mosaics of cultivated land mixed with trees and pastures, and therefore possess just slightly more than half of the world’s total crop-covered area (8 of 15 million km2), with most of the remaining cultivated area found in Village (~25%) and Rangeland (~15%) biomes. While Forested biomes are host to a greater extent of Earth’s tree-covered land, about a quarter of Earth’s tree cover was found in Croplands biomes, a greater extent than that found in Wild forests (~20%).While not a replacement for existing biome systems based on vegetation and climate, anthropogenic biomes offer a new view of the terrestrial biosphere based on the irreversible coupling of human and ecological systems at global scale. This new model of the biosphere moves us away from an outdated view of the world as “natural ecosystems with humans disturbing them” and towards a vision of “human systems with natural ecosystems embedded within them”.
This is a major change in perspective that may prove critical for sustainable management of our biosphere in the 21st century.
Subscribers can also view the work online at http://www.esajournals.org/perlserv/?request=get-abstract&doi=10.1890/070062
View the new maps online in Google Earth at the Encyclopedia of Earth:http://www.eoearth.org/article/Anthropogenic_biome_mapsJoin the BLOG: Can we conserve nature in an anthropogenic biosphere?http://www.earthportal.org/forum/?p=410Contributed by Erle Ellis, University of Maryland, Baltimore County