Ecology Terms Starting With T
Ecology Glossary: T
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Taiga
/ TY-guh / · Russian taiga (forest, from Mongolian)
Taiga is the largest terrestrial biome on Earth, stretching across northern North America, Europe, and Russia where spruce and larch trees grow so densely that they form a continuous belt just south of the Arctic tundra.
The taiga covers about 17 million km2 and stores about 20 Gt (gigatonnes) of carbon in vegetation and soils, more than any other biome. Climate here is marked by long, cold winters, short cool summers, and low annual precipitation, with many lakes and wetlands resulting from glacial drainage patterns. Fire is the primary disturbance agent in boreal forests.
The taiga stores nearly twice as much carbon per square kilometer as tropical rainforests, holding approximately 30 percent of all carbon stored in Earth's terrestrial ecosystems. Some boreal forest fires burn underground in peat for months, even through winter.
All forests are similar if they have trees. Taiga forests have long cold winters, acidic soils, and species adapted to short growing seasons.
Canada's boreal forest contains black spruce, mosses, wolves, moose, and migratory birds. Fire is a natural disturbance in many taiga regions.
Terrestrial Ecosystem
/ teh-RES-tree-ul EE-koh-sis-tem / · Latin terrestris (of the earth) + Greek oikos + systema
Terrestrial Ecosystem terrestrial ecosystem is a community of living organisms and their nonliving physical environment on land, such as the forest biome in temperate North America or the savanna grasslands of Africa.
Land-based ecosystems contain soil microorganisms, plants, arthropods, and vertebrates that interact within specific temperature and precipitation ranges. Energy from sunlight flows through photosynthesis into plants, then herbivores, carnivores, and decomposers. Nutrient cycles like nitrogen fixation by soil bacteria and phosphorus weathering from rock recycle essential elements back to the soil.
Disturbances such as fire, grazing, and drought shape ecosystem structure and composition.
Tropical rainforests cover about 6 percent of Earth's land but contain roughly 50 percent of all terrestrial species.
Terrestrial ecosystems exclude water completely. Soil moisture, groundwater, streams, rainfall, and fog all sustain terrestrial life.
A temperate grassland contains native grasses, legumes, soil invertebrates, insect herbivores, grazing mammals like bison, and predators like hawks. Fire and herbivory prevent woody plants from taking over.
Order Fabales →Trophic Cascade
/ TROF-ik kas-KAYD / · Greek trophikos (of nourishing) + Latin cascada (waterfall)
Trophic Cascade is an indirect ecological effect in which the removal or addition of a top predator propagates downward through the food web, altering the abundance and behavior of prey.
A top-down trophic cascade happens when predators reduce the number or behavior of plant-eating animals. This can allow plants to become more abundant. A bottom-up cascade begins when changes in producers affect animals higher in the food web.
A trophic cascade occurs when changes at one feeding level affect other levels below or above it. Predators can indirectly influence plants by affecting herbivores.
Predators only affect the animals they eat directly. Predator effects ripple through the food web, changing the behavior and abundance of prey species and indirectly affecting the plants those prey eat.
In kelp forests, sea otters eat sea urchins that graze kelp. When otters are present, kelp forests can become denser.
What Do Otters Eat? →Trophic Level
/ TROF-ik LEV-ul / · Greek trophikos (of nourishing) + Latin libella (level)
Trophic Level is a step in a food chain representing a category of organisms that obtain energy from the same source, with primary producers at the base as level 1 and successive consumers at higher levels.
Energy transfer between trophic levels is about 10% efficient, with about 90% of energy lost as metabolic heat at each level. This limits food chains to four. Trophic level assignment is complicated in omnivores that feed at multiple levels and in parasites.
A trophic level describes an organism's feeding position in an energy pathway. Some animals can occupy more than one trophic level if they eat varied foods.
Every species fits one fixed trophic level. Omnivores and animals with changing diets can shift levels.
A grasshopper feeding on grass is a primary consumer. A frog that eats the grasshopper is at a higher trophic level.
What Do Frogs Eat? →Tundra
/ TUN-druh / · Finnish tunturi (treeless upland)
Tundra is a biome marked by extremely cold temperatures, short growing seasons, permafrost, low biodiversity, and vegetation dominated by mosses, lichens, sedges, and dwarf shrubs, found both at high latitudes as Arctic tundra and at high altitudes as alpine tundra.
Arctic tundra is underlain by permafrost, permanently frozen subsoil that prevents deep rooting, causes surface waterlogging in summer when the active layer thaws, and stores enormous amounts of organic carbon. Tundra vegetation is low-growing, cold-adapted, and nitrogen-limited; the growing season may be only 6 to 10 weeks. Climate warming is disproportionately fast in Arctic regions, a pattern called Arctic amplification, causing permafrost thaw that releases stored methane and carbon dioxide and may create a positive feedback that accelerates global warming.
Arctic tundra permafrost contains an estimated 1,700 billion tonnes of frozen carbon, nearly twice the amount currently in Earth's atmosphere. Some permafrost has remained frozen for over 700,000 years but is now thawing at rates up to 18 centimeters per year in Alaska.
Tundra is lifeless because of the harsh conditions. Over 1,700 species of plants and numerous mammals, birds, and insects thrive there, with some Arctic regions supporting caribou herds numbering over 200,000 individuals.
Arctic tundra supports caribou, Arctic foxes, lemmings, sedges, mosses, and lichens. Many birds migrate there to breed during the short summer.