Where Have all the Biomes Gone? ELF Activity: 1B

Biomes are the world's major natural communities, generally defined according to the dominant vegetation. Organisms in a specific biome tend to have similar adaptive characteristics; for example, they might be able to tolerate drought, low temperatures, short growing seasons or high winds.

Throughout the history of the Earth, biomes have shifted as regional climates have changed. Now, human activities are beginning to alter the factors that influence biomes. As the Earth’s climate changes, biomes are shifting and organisms must adapt or move; otherwise, they will die out.

Biomes vary with latitude and region. For instance, tree line determines the elevation above which trees will stop growing due to harsh climate factors. Tree line occurs at different elevations depending on latitude. Observe the following table and note the general trend of lower tree line elevation with increasing latitude.

LocationLatitudeTree line m/ft Costa Rica90N90N3400/11,200 Hawaii20 0 N2800/9200 Sierra Nevada, CA38 0 N3200/10,500 Maine46 0 N1150/3770 Alaska61 0 N700/2300 With some exceptions the worldwide trend is, “The higher the latitude, the lower the tree line.”

Hotspots refer to regions of high biodiversity which are currently experiencing loss of habitat. For example: California This state has hot dry summers and cool moist winters and contains several ecosystems. Of the 3500 native plants, 2100 (60%) are found nowhere else on the planet. 50% of the amphibians and 11% of the mammals are also endemic. Only 37% of the land is protected. Human development (both urban and agriculture) threatens many of these species. There are only 25 biodiversity hot spots throughout the world. What are Hotspots?

The following slides introduce the major biomes of the world.

Abundant rainfall and year-round warmth. This biome is the most complex and hosts the greatest biodiversity. Dominated by large broadleaf trees, ferns, vines, colorful birds, and an abundance of species of mammals, amphibians, and insects. Warm and Very Wet – Tropical Rainforest Found mainly between 10 o N and 10 o S.

Temperate areas, inches of rain per year, warm to hot summers. Dominated by perennial grasses. Bison, pronghorn antelope, ground squirrels, prairie dogs, coyotes, mice, rabbits, sage grouse, and many songbirds. Warm and Semi-Wet – Grasslands

Less than 10 inches of rain per year; temperatures may reach above 100 o F in summer. Shrubs have small thick leaves. Plants and animals adapted to tolerate high temperatures and sparse water resources. Animals mostly nocturnal and light-colored to reflect the sunlight. Warm and Dry – Desert

20-60 inches of precipitation per year. Warm summers, cold winters. Deciduous trees dominate the region with some conifers. Oak, elm, maple, beech, and hickory are common. Shrubs, flowering herbs with ground lichen and moss add to the biodiversity of this biome. Bears, deer, squirrels, chipmunks, skunks, raccoons, and many seed- and insect-eating birds. Cool and Wet – Broadleaf Forest

Cold long winters and wet summers. Dominated by conifers (pine, fir, spruce), with some broadleaf trees (alder, birch aspen). Abundant migratory birds and fur-bearing mammals (martens, bears, lynx, squirrels, voles, weasels, beavers). Large herbivores include elk, moose, and deer. Cold and Wet – Pine Forest

Similar to the Arctic Tundra except receives more precipitation. Found at higher elevations in the middle and lower latitudes. Mosses, lichens, grasses, low shrubs; no trees above tree line. Mammals include picas, marmots, migratory birds, and small rodents. Cold and Wet – Arctic Alpine

Cold, long, dark winters; low precipitation. Treeless land with few species. Lichens, mosses, sedges, heath, and low shrubs. Ptarmigans, muskoxen, arctic hares, arctic foxes. High latitudes in the Northern Hemisphere. Cold and Dry – Tundra

Ocean environments found worldwide. Highly diverse depending on water temperature, depth, and presence of nutrients. Wet – Marine

In this activity, students sort organisms into the world’s biomes based on their knowledge or on the organism’s adaptive characteristics which make it suitable to live in that biome. Then students sort fossil organisms into the Earth’s current biomes. When it is revealed where the fossils were actual found, students see that the world’s biomes have not always been in the same place.

All photos in this slide presentation are courtesy of the U.S. Bureau of Land Management:

This material is based on work supported by an Environmental Literacy Grant from the National Oceanic and Atmospheric Administration’s Office of Education (NA09SEC ) and prior work supported by the National Science Foundation under Grants ANT and ESI Any opinions, findings, and conclusions or recommendations expressed in these materials are those of the authors and do not necessarily reflect the views of the National Oceanic and Atmospheric Administration or the National Science Foundation.