50 Fun Facts About Ecosystems

Which rodents, the textbook ecosystem engineers, turn streams into ponds that other species use?

Beavers dam streams with trees they fell themselves, and the ponds and wetlands that form behind the dams trap sediment and pollutants that would otherwise wash downstream.

Which animals, freed for hunting in Australia in 1859, grew into a plague of hundreds of millions?

Rabbits spread so fast that within ten years two million a year could be shot or trapped with no visible effect. A virus released in 1950 finally cut an estimated 600 million down to about 100 million.

Gray wolves, moose and wild horses now roam the evacuated zone around which nuclear disaster site?

Chernobyl was evacuated in 1986, and since then its wolves, wild boar, red deer and moose have multiplied so much that they have begun spreading beyond the zone.

Which giant snakes from Southeast Asia, once sold as pets, now hunt the mammals of the Everglades?

Burmese pythons were recognized as a breeding population in the Everglades in 2000, and road surveys since then suggest sightings of raccoons, opossums and bobcats have fallen sharply where the snakes spread.

Which bird, once the most abundant in North America at some three billion, was extinct by 1914?

Passenger pigeon flocks could take hours to pass overhead, but commercial hunting on a huge scale and the clearing of forests wiped them out. The last bird, Martha, died at the Cincinnati Zoo.

Coral bleaching happens when heat-stressed corals expel which tiny partners living in their tissues?

Algae called zooxanthellae give corals their color and up to 90 percent of their energy, so a coral that stays bleached for long may begin to starve.

Which volcano's 1980 eruption has been studied by ecologists more than any other eruption?

Mount St. Helens has had more ecological study than any other eruption, because researchers moved in at once and the blast had not sterilized the ground around it.

Which Japanese vine, planted in the American South to hold soil, now smothers trees and buildings?

Kudzu arrived from Japan at the 1876 Centennial Exposition in Philadelphia and was first sold as a vine to shade porches, before farmers were handed it as cattle fodder and ground cover.

Which Central Asian lake shrank to a tenth of its size after its rivers were diverted to farms?

The Aral Sea began shrinking in the 1960s, when Soviet planners diverted the two rivers feeding it to irrigate cotton fields. Part of the old lake bed is now called the Aralkum Desert.

Which 1930s disaster hit the Great Plains after farmers plowed up the grasses that held the soil?

The Dust Bowl followed a decade of deep plowing that stripped the plains of native grasses, so when drought came, the wind lifted the loose earth into clouds that reached New York and Washington.

Which role in an ecosystem do trees, grasses and seaweeds fill by making their own food from sunlight?

Producers sit at the bottom of every food chain, supplying both the energy that other living things consume and the oxygen that they breathe.

Which term names primary consumers such as deer and grasshoppers?

Herbivores are called primary consumers because they are the first animals in a food chain, able to live on tough, fibrous plants alone. The Latin form, herbivora, turns up in Charles Lyell's 1830 Principles of Geology.

Millipedes, woodlice and slugs fill which ecosystem role by eating dead leaves and droppings?

Detritivores swallow lumps of dead matter and so speed up decay, unlike fungi and bacteria, which cannot take in solid pieces and must absorb their food molecule by molecule.

Which word do ecologists use for the role a species plays in its ecosystem?

Niche sums up how a species makes its living, and two species cannot share an identical one for long: when they compete, one eventually drives the other out.

Which label do ecologists give a species whose removal would drastically change its whole ecosystem?

Keystone species matter far more than their numbers suggest. Robert Paine showed it by removing starfish from a Washington shore: the mussels they had been eating quickly crowded out the other species.

Clownfish shelter in sea anemones and chase off fish that eat them, a case of which relationship?

Mutualism means both partners come out ahead: the anemone's stinging tentacles keep predators off the clownfish, and the clownfish chase away the butterflyfish that feed on anemones.

Which bird lays its eggs in the nests of reed warblers and pipits, leaving them to raise the chick?

Cuckoo chicks can hatch before the host's own young and push the remaining eggs out of the nest, so the foster parents pour all their effort into feeding the intruder.

Which service do bees, butterflies and hummingbirds perform as they feed from flower to flower?

Pollination lets most flowering plants set seed, and it pays farmers too: fields close to wild habitat get more insect visitors and so produce higher crop yields.

Which diagram shows what eats what across a whole ecosystem by joining many feeding paths together?

A food web is many food chains woven together. The name replaced 'food cycle', the term Charles Elton used in his 1927 book Animal Ecology.

Which fish rides on sharks and turtles using a sucker on its head, a classic case of commensalism?

Remora cling on with a dorsal fin reshaped into an oval suction disc, and spend most of their lives attached to a host, which earned them the nickname sharksucker.

Which term, written as K in growth equations, is the largest population an environment can support?

Carrying capacity is set by the food, water, shelter and other resources on offer, and as a growing population closes in on it, growth slows and the numbers level off.

Which kind of factor is a flood or wildfire, which kills no matter how crowded a population is?

Density-independent factors are usually physical, such as weather, natural disasters and pollution, whereas disease and competition bite harder as a population gets more crowded.

Which term covers anything in short supply, such as light on a forest floor, that holds back growth?

A limiting factor works by Liebig's law of the minimum: growth is set by the scarcest resource, not by the total amount of resources available.

Which animals, 29 of them left on Alaska's St. Matthew Island in 1944, boomed to 6,000 and then crashed?

Reindeer were put ashore by the US Coast Guard as an emergency food supply and then abandoned. The herd peaked at about 6,000 in 1963, fell to 42 within two years and had died out by the 1980s.

White-nose syndrome, a fungus first spotted in a New York cave in 2006, has killed millions of which animals?

Bats with the disease carry a fungus on their skin, and by 2012 an estimated 5.7 to 6.7 million had died across North America, leaving huge numbers of insects uneaten.

Yeast in a test tube booms, slows and levels off, tracing which curve shape typical of logistic growth?

S-shaped curves appear whenever resources run short: growth is fast at first, slows as supplies get scarce and then flattens, while unlimited resources would give a J-shaped curve instead.

Which effect describes animals in a very small population struggling to find mates or defend themselves as a group?

The Allee effect is named for Warder Clyde Allee, who showed in the 1930s that goldfish survive better when more of them share a tank, reversing the usual rule that crowding slows growth.

Which English clergyman's 1798 essay on population outrunning food supply influenced Charles Darwin?

Thomas Malthus argued that population grows exponentially while food production grows only arithmetically, and both Charles Darwin and Alfred Russel Wallace were among his readers.

In ecology, which word names all the populations of different species living together in one area?

A community is only the living part of the picture: add the non-living surroundings, such as air, water and soil, and the whole thing becomes an ecosystem.

Which word, coined by geologist Eduard Suess in 1875, names the worldwide sum of all ecosystems?

The biosphere is also called the zone of life on Earth, and Suess defined it simply as the place on the planet's surface where life dwells.

Which kind of succession follows a forest fire or an abandoned field, where soil and buried seeds survive?

Secondary succession is usually the faster kind, because soil is already in place and seeds, roots and underground stems may still be alive in it.

Lichens and mosses that are first to colonize bare rock and start making soil are which kind of species?

Pioneer species do not last: as they die and decay they build up the first thin soil, which lets grasses and shrubs move in and replace them.

Which volcanic island, born off Iceland in 1963, is kept off limits so scientists can watch life arrive?

Surtsey was declared a nature reserve in 1965, while the eruption was still going on, and that same spring the first vascular plant was found growing on its northern shore.

Which term describes the knock-on effects that run down a food chain when top predators are removed?

Aldo Leopold is generally credited with first describing a trophic cascade, after watching deer overgraze mountain slopes once people had wiped out the wolves.

Which gas makes up 78% of the air yet must be 'fixed' by bacteria or lightning before plants can use it?

Nitrogen is all around us but mostly out of reach: lightning fixes 5 to 10 billion kg a year, and most of the rest is fixed by bacteria, some living in the root nodules of clover and soybeans.

Which process releases water vapor from a plant's leaves through tiny pores called stomata?

Transpiration accounts for nearly all the water a plant drinks: only a sliver is kept for growth, and 97 to 99.5 percent is lost again, mostly through the leaves.

Which two-word term describes a forest or ocean that soaks up more CO2 from the air than it gives off?

A carbon sink can be natural or artificial, and the two most important on Earth are vegetation and the ocean, which is why protecting forests and soils counts as climate action.

Which Pacific warming event, first named by Peruvian fishermen, makes anchovy stocks crash?

El Niño weakens the trade winds, so less cold deep water wells up off Peru. Anchovy collapses and a fishing crisis followed the events of 1972–73, 1982–83 and 1997–98.

Which term covers the non-living parts of an ecosystem, such as light, temperature, water and soil?

Abiotic conditions decide what can live where, and some life is built for the extremes: many archaea need very high temperatures, pressures or doses of chemicals such as sulfur.

Which English botanist, a one-time student of Sigmund Freud, introduced the ecosystem concept in 1935?

Arthur Tansley framed the idea in a 1935 paper on the misuse of botanical terms, but the word itself was thought up, at his request, by Arthur Roy Clapham.

Which process, driven by fertilizer runoff, clogs lakes with blooms that use up the oxygen fish need?

Eutrophication is fed by sewage and factory waste as well as farms, and the worst cases leave 'dead zones' of water that hold no oxygen at all.

Which term describes an introduced organism, such as the cane toad in Australia, that harms its new home?

Invasive species often travel by accident: the zebra mussels of North America's Great Lakes most likely arrived from Eurasia in the ballast water of ships.

Which venomous striped fish from the Indo-Pacific, a popular aquarium pet, has overrun Caribbean reefs?

Lionfish were found off Dania Beach, Florida, as early as 1985, and the invaders resemble fish from the Philippines, which suggests they descend from pets that aquarium owners discarded.

Which crop, over 80% of it grown in Indonesia and Malaysia, is planted on cleared orangutan rainforest?

Oil palm plantations need forest cleared on a huge scale, and a 2018 study found more than 100,000 orangutans were lost between 1999 and 2015 to resource exploitation, the palm oil industry included.

Which term describes roads and farms carving a large habitat into small, isolated patches?

Fragmentation does more than shrink a habitat: the edge of each leftover patch has a different climate from the interior, so it favors different species.

Which spiny grazers strip Alaskan kelp forests bare when sea otters are not there to eat them?

Sea urchins multiply dramatically once their predators are gone, and the stripped seabed they leave behind is known to biologists as an urchin barren.

Which Appalachian tree lost more than three billion of its kind to a blight from Japan after 1904?

American chestnut was a dominant tree of the Appalachians until an airborne bark fungus, spreading about 50 miles a year, girdled and killed the mature trees within a few decades.

Which phrase, the title of Garrett Hardin's 1968 essay, describes herders overgrazing land they all share?

The tragedy of the commons draws on an 1833 pamphlet by William Forster Lloyd, who imagined each herder adding cattle for his own gain while the damage was shared by all.

On which Pacific island did the brown tree snake, a stowaway after World War II, wipe out most native birds?

Guam offered the snake plenty of prey and no predators, so it thrived. Trained dogs now search outbound cargo to stop it reaching other islands.

In which African lake did Nile perch, added in the 1950s, drive hundreds of native species to or near extinction?

Victoria's native cichlids were the perch's first prey, and once they grew scarce the perch itself had to switch to eating mainly small shrimp and minnows.