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Expert-reviewed information about the Earth.  For everyone.

  • Earth's atmospheric air Featured Article Earth's atmospheric air Earth's atmospheric air

    The Earth's atmospheric air is a colorless, odorless and tasteless mixture of gases consisting mostly of nitrogen (N2) and oxygen (O2). It is the part of Earth's... More »

  • Composting Featured Article Composting Composting

    Composting is the controlled biological decomposition and pasteurization of organic materials under aerobic conditions— it involves the action of mesophilic microorganisms... More »

  • Fluid catalytic cracking Featured Article Fluid catalytic cracking Fluid catalytic cracking

    Fluid catalytic cracking (FCC) is the most important conversion process used in petroleum refineries. It is widely used to convert the high-boiling hydrocarbon fractions of... More »

  • Europa Island Featured Article Europa Island Europa Island

    Europa Island located in the southern Mozambique Channel, between Madagascar and Mozambique. Europa Island is about 100 kilometers (km) southeast of Bassas da... More »

  • Vertical farming Featured Article Vertical farming Vertical farming

    The advent of agriculture ushered in an unprecedented increase in the human population and their domesticated animals. Farming catalyzed the transformation of hunter-gatherers... More »

  • What Is Aquaculture? Featured Article What Is Aquaculture? What Is Aquaculture?

    The term aquaculture broadly refers to the cultivation of aquatic organisms in controlled aquatic environments for any commercial, recreational or public purpose. The breeding,... More »

  • Cnidaria Featured Article Cnidaria Cnidaria

    Cnidaria (corals, jellyfish, and Hydra) are incredibly diverse in form, as evidenced by colonial siphonophores, massive medusae and corals, feathery hydroids, and box jellies... More »

Recently Updated
Guayanan Highlands moist forests Last Updated on 2014-04-22 19:21:56 This ecoregion is located in the highlands of southern Venezuela and northern Brazil, and extends into western Guyana and eastern Colombia. The region sits on the Guayanan Shield which underlies the northern region of South America. It hosts vast expanses of tall primary rainforest and open, treeless or nearly treeless savannas, and rich gallery forests. Elevations range from 500-1500 meters above sea level, and the climate is seasonal and humid, with 2,000-2,400 millimeters (mm) rainfall annually. Here, rugged terrain and unique creatures abound, as this region is an elevational "island" surrounded by llanos and lowland forest.   Situated in southeastern Venezuela in northern South America, the Guayanan Highlands ecoregion is distinct from other ecoregions in Amazonia due to its montane physiography. It hosts vast expanses of tall primary rainforest and open,... More »
Kalaallit Nunaat low arctic tundra Last Updated on 2014-04-22 19:11:32 The Kalaallit Nunaat low arctic tundra is the southernmost of the two ecoregions of Greenland; this tundra ecoregion lies below 75°N latitude at Melville Bay on the west coast and 70°N at Scoresby Sund on the east coast. This region is bisected by the Arctic circle. Kalaallit Nunaat is actually the local name for Greenland, which island is geographically a part of North America, though politically a member of Europe. With a total area of over two million square kilometers, Greenland is the world's largest island. However, four-fifths of this vast land area lies beneath a sheet of ice. Low arctic tundra covers the ice-free coastal region of southern Greenland, mostly covered in stunted vegetation, yet teeming with wildflowers such as chamomile, dandelion, harebell, and Arctic poppies, and also wild berries in the lowland areas during summer. Few animals tolerate the harsh... More »
Kalaallit Nunaat high arctic tundra Last Updated on 2014-04-22 19:08:11 Claiming the most northern reaches of land on Earth, the Kalaallit Nunaat high arctic tundra of northern Greenland, or Kalaallit Nunaat as it is known locally, is a unique and fragile ecosystem. The Kalaallit Nunaat is one of only two ecoregions of Greenland. Veiled in near-darkness for as many as four months out of the year and enduring summer temperatures that seldom exceed 5°C, this ecoregion supports only plants and animals adapted to the most extreme of conditions. Often existing at their limits of survival, the natural assembly of this ecoregion is vulnerable to even minor disruptions. The muskox, arctic wolf, polar bear, seals, and others of this ecoregion were heavily targeted by hunters in the past, but are mostly recuperating under new regulations. The largest National Park in the world, covering 1,000,000 square kilometers (km2), was established here in 1974. A... More »
Beringia upland tundra Last Updated on 2014-04-22 19:04:14 The Beringia Upland Tundra consists of three disjunct areas on the Bering Sea coast of Alaska, one comprised of the upland and mountainous areas of Seward Peninsula, one corresp- onding to the hills and mountains of the Ahklun and Kilbuck mountain ranges in southwest Alaska, and one of much smaller extent on the western half of St. Lawrence Island in the northern Bering Sea. These areas are similar in their varied terrain and elevation, and corresponding variety of vegetation, habitats, and communities. The ecoregion consists of steep, jagged mountain ranges set among large areas of rolling hills, broad valleys, and lowlands. Elevation ranges from sea level to 500 meters (m) in the hilly uplands to over 1,500 m in the tallest ranges. Plant communities respond to these differences in topography and accompanying drainage. Low-lying, poorly drained areas support wet graminoid... More »
Beringia lowland tundra Last Updated on 2014-04-22 18:58:15   The Beringia lowland tundra ecoregion is formed by three major disjunct areas along the Bering Sea coast of Alaska from the base of the Alaska Peninsula to Kotzebue Sound, as well as one smaller area on the east side of St. Lawrence Island and St. Matthew Island. The ecoregion is characterized by low, flat, or gently rolling terrain, wet soils, and resulting predominance of wet and mesic graminoid herbaceous vegetation. In better drained areas, especially in the somewhat more rolling portions of the section surrounding Bristol Bay, dwarf shrub communities occur interspersed with the wet herbaceous tundra, dominated by sedges, including Eriophorum angustoifolium and Carex spp. Dwarf shrub vegetation is usually dominated by ericaceous species, including crowberry (Empetrum nigrum). In some limited areas of favorable soil drainage and microclimate, stands of black and white... More »