Beartooth Pass -- Timberline (Tundra)
Beartooth Pass Highway, Wyoming, July, 1999

GENERAL CHARACTERISTICS

Northernmost land in world - treeless rolling plain that spreads across top of each continent surrounding Arctic Ocean.

Tundra covers much of Alaskan coast and northern Canada.

Arctic Circle which goes through tundra is imaginary line that marks beginning of land of midnight sun. At Arctic Circle there is one day in June when sun never sets and one day in December when it never rises. Going north from the Arctic Circle the number of days of 24 hour sunlight in summer (and total darkness in winter) gradually increases until at the North Pole there is continuous sunlight half the year.

Tundra is rock-strewn hills and boggy meadows alternating with thousands of lakes and ponds.

Characterized by permafrost about 12 inches down and in some cases up to one mile deep. In winter, tundra freezes solid but when spring comes, top part of soil thaws. The top thawed layer is the active layer where plants grow but trees can’t because of the need for roots.

Permafrost is very important to whole makeup of tundra because it prevents H₂0 from seeping away through soil. Without permafrost, tundra would look like desert since climate is surprisingly dry.

Most of area receives less than 9.8 inches of precipitation a year, half as rain and half as snow. This is same amount of H₂0 that falls on desert. In order to snow, there has to be a lot of moisture in air . Climate is dry but land is very wet. Two-thirds of tundra covered by H₂0; marshes, ponds and lakes are here. Frozen soil holds H₂0 like a plastic liner in a swimming pool. The small amount of snow that does fall melts each summer.

PLANTS

Spring comes about May and by early July everything is in full bloom. During this short summer, tundra is completely green. Flowers bloom everywhere. Grass sprouts in the marshes. Moss beds unfold and lichens begin to grow. Shrubs such as dwarf willow, birch and alder grow. Although this only lasts for a few weeks, there is lots of daylight so things grow fast.

The plants that are able to do well in the tundra do so because of several adaptations. Most are small plants that grow low to the ground. They are very efficient at gathering and storing energy from the sun even at cool temperatures. They are able to withstand drought, wind and cold.

Lichens predominate in tundra. About 2500 kinds in Arctic and they grow on soils and bare surfaces of rocks. They have no leaves, roots, stems or flowers. Lichens are two organisms - an alga and a fungus living together. The alga makes the food and the fungus provides a tough, protective coating for alga and helps store water. There are incredible amounts of lichens in tundra and they provide food for caribou.

In really wet places on tundra, mosses take over. Mosses are more advanced then lichens but they are still very simple plants and have no true roots, leaves or flowers.

ANIMALS

Tundra plants provide food for tundra animals: ground squirrels, lemmings and ptarmigan (chicken-like birds) eat seeds and shoots. Caribou eat lichens and grasses. Musk ox eat willow and other small plants. Musk ox eat only plants and wolves can eat musk ox although rarely. Wolves mainly eat the caribou. Snowy owl and fox eat lemmings.

During summer, incredibly large numbers of insects emerge and this is what birds feed on. Millions of birds migrate to tundra in the spring.

Ground Squirrel - gets through winter by hibernating. Heartbeat goes from 200 to 5-10; temperature drops to just above freezing.

Lemmings - spend winter eating and sleeping in tunnels under snow. Because they remain active, they are the prey that keep snowy owl and fox alive during winter as well as summer. Arctic Fox - short nose and small ears help reduce heat loss. Also capable of camouflage.

Ox - superior two-layered coat. Outer layer very long and hangs down to ankles and sways; thick coat underneath of fine, soft sheep-like wool.

Ptarmigan- camouflage - white in winter and brown in summer.

Reference

Hiscock, B. 1986. Tundra: The Arctic Land.

Sayre, A.P. 1994. Tundra.

Stretches across northern parts of N. America, Europe and Asia; specifically across Alaska and bulk of Canada.

General Characteristics:

Temp. - 65^o F to 30^o F in winter
20^o F to 70^o F in summer

Winter cold with some snowfall
Precipitation 12-33"/year - Most is rain in summer but in northern parts of taiga there is snow for 9 months of year.
Land - areas of closed forest taiga with trees close together and further north trees spread farther apart and lichen covers ground.


A Land Shaped by Ice

18,000 years ago, where Canada’s taiga is today, ice was piled high, in places a mile thick! During the last ice age, glaciers moved down over Canada, parts of Alaska and the northern portion of the U.S.

When the earth’s climate finally warmed and the ice melted, the land was almost bare of soil since the weight of the ice had scraped the soil off the land. It took thousands of years for soil to develop and forests to become reestablished, but eventually taiga trees and plants that had survived in large unglaciated regions reseeded the area.

The lakes and ponds in the taiga were formed when ₂0 filled up large pits carved out by glaciers. As a result of its glacial history, most of taiga’s soil is young and has not had time to develop the deep, thick layers of fertile soil present in many other areas. Because soil development progresses slowly in cold climates, taiga soils are thin and not very good for farming. Even if the soil has the minerals plants need, it’s so cold that plants cannot use much of this mineral content. At low soil temperatures, plants cannot efficiently carry out the chemical reactions needed to absorb minerals.

Also, temperatures are so cool in the taiga much of the year that the organisms that break down material into soil are not very active. As a result, the taiga’s organic material does not decompose quickly; it piles up.


Taiga Plants

Mostly conifers (fir, spruce) but also poplar, alder, willow and birch. Undergrowth includes low-lying shrubs, mosses and grasses which form spongy ground cover. In a land where growing seasons are short, there is little time for a tree to grow new leaves each spring. In the taiga, where both available soil nutrients and growing time are scarce, growing a whole new set of leaves each year is doubly difficult and thus, most taiga tree are evergreens, i.e. they keep their leaves for more than one season. A spruce may keep its needles for 15 years while other species may keep theirs for two or three years. Evergreen trees lose their needles only a few at a time, gradually so the loss may not be noticeable. Deciduous trees, however, lose their leaves every fall and regrow them in the spring. Both evergreen and deciduous lifestyles have their advantages. Deciduous trees, by shedding their leaves, use less energy during winter and don’t run the risk of snow and ice building up on their leaves and breaking their branches. Evergreen trees, by keeping their leaves, don’t have to grow a whole new set of leaves at the start of the next growing season. But they do risk snow buildup and branch breakage. This is one reason conifer trees are cone-shaped, with branches that droop downward to help them shed snow. Being evergreen is just one of the many adaptations of trees in the taiga. There are also others.

Reproduction

Conifers have neither flowers nor fruits. In late winter or early spring, they form two kinds of cones--cones that have pollen and cones that are fertilized by wind-blown pollen. Pollen blows from tree to tree fertilizing the cone. Once a cone is fertilized, it grows larger and its seeds develop under tightly closed scales. When the seeds are ripe and the cone dries out, it opens and the seeds land on the ground there they sprout into new trees.

Needles and Leaves

Conifers have needles instead of broad leaves. Long, thin, wax-covered needles lose less H₂0, retain more heat and shed snow more easily than broad leaves. Conservation of water is important because rain may fall on branches and never reach tree roots and cold temperatures make it difficult for trees to absorb what H₂0 is present in the environment.

Winterizing and Frostbite

To survive long, cold snowy winters, taiga trees winterize. In fall, they slow the chemical processes going on in their tissues. They also undergo a process called hardening which makes them more resistant to freezing.

Fire Survivors

Fire is a recurring event in the taiga, so many taiga trees are adapted to it. Thick bark protects some trees from mild, low-heat fires. Conifers are designed so that if fires move through forest, some of the cones or high branches may survive. The heat of the fire makes the cones open and the seeds drop to the ground to reseed the forest floor.

Fungi

Taiga conifer trees have fungi attached to roots which help them get H₂0 and minerals from soil. In return, fungi get some of the food that the conifers make.

Coniferous trees are not the only plants in the taiga. Some deciduous trees also grow there. Underneath taiga trees small herbs, mushrooms, lichens, and mosses grow. And wherever enough sunlight enters the forest, various shrubs grow.


Taiga Animals

Birds, squirrel and numerous small mammals, bear, deer, moose, insects, wolves; no amphibians and reptiles.

Animal Adaptations
Migration. Of the 300 bird species that live in the taiga in summer, only 30 species stay for the winter. The rest are summer visitors who leave in the fall migrating as far south as South America. Why do millions of birds travel thousands of miles to taiga each year? Insects, like tundra, they are all over the place.
Hibernation. Squirrels hibernate.
Snow Blankets. Variety of small mammals and hares tunnel down into snow to keep warm. Just 10 inches under blanket of snow, temperature remains fairly constant, about 32^o F. What also happens is that the summer warmth, trapped in the ground, melts some of the winter snow closest to the ground. Melting, dripping, then refreezing, the snow forms a sort of crystal palace--open spaces interspersed with "columns" made of ice and snow. Several inches thick, this layer allows small mammals to stay active within its warm spaces. At times, however, the breath of these animals creates a toxic buildup of C0₂. To alleviate this problem, rodents dig ventilation shafts to surface for air.
Natural Snowshoes

Hares and lynx have broad furry paws which enable them to walk on snow.

Camouflage

Snowshoe hares, ptarmigans, weasels, etc. change coat color.

Ability to Change Diet

Spruce grouse are chicken-like birds and they like insects and seeds, but when winter comes they will eat spruce needles. Other animals eat tree bark.


Reference

Sayre, A.P. 1994. Taiga.






TROPICAL RAIN FORESTS November 19, 1999

Dr. Howard


Cover only 2% of Earth’s land surface but contain almost half of world’s growing wood and one-third of its plant matter. Estimates of total number of animal species range from 60% to as high as 99%.


WHY WE SHOULD CARE ABOUT TROPICAL RAIN FORESTS

• Supply half of world’s annual harvest of hardwood.
  
• Provide hundreds of food products including coffee, tea, cocoa, spices, nuts, chocolate, tropical fruits.
  
• Provide materials such as natural latex rubber, dyes, and essential oils.
  Active ingredients for 25% of world’s prescription drugs are substances derived from plants in tropical rain forests. Drugs are used in tranquilizers, muscle relaxers, and life-saving drugs for treating malaria, leukemia, Hodgkin’s disease, testicular and lung cancer, heart disease, high blood pressure, multiple sclerosis, and many other diseases.
  
• 70% of the 300 plants identified by NCI as sources of cancer fighting chemicals come from tropical forests.
  
• It was estimated that tens of thousands of strains of plants with potential food value reside in tropical rain forests.


EFFECTS OF DEFORESTATION ALTERATION OF EARTH’S CLIMATE

1. Trees are rain machines and recycle water back into atmosphere. Deforested areas receive lower amounts of rainfall and most runs off into streams.

2. Forests are critical to balance of CO₂ on earth. Deforestation releases massive amounts of CO₂ into atmosphere which traps heat and hastens global warming.


STRUCTURE OF AMAZON RAINFOREST

Occupies 2.3 million square miles of South America. Amazon holds 1/5 of world’s freshwater. The Amazon rainforest is structured as follows:

A. Forest Floor (0 feet)
B. Understory (0-60 feet)
C. Canopy (60 - 130 feet)
D. Emergent Layer (130 - 160 feet)

A. Forest Floor Few low-growing plants survive here because of the lack of sunlight. The ground is carpeted with a thin layer of rotting leaves and branches which the decomposers feed upon. Insects and other creatures such as worms feed upon the fungi and lizards, frogs, small snakes, turtles, and occasionally birds or mammals feed on the decomposer eaters.

B. Understory Home to small trees and shrubs that are well adapted to low light. Several animals live on the trunks and branches of the understory. Numerous insects, such as katydids and packs of army ants live here and are consumed by insect-eating frogs, lizards and small mammals. Jaguars are understory travelers as are 18-foot long boa constrictors and they eat small mammals.

C. Canopy The canopy is comprised of medium-size trees, more than 60 feet in height. More animals live in the canopy than in any other part of the forest--countless species of insects, mixed flocks of birds, fluttering butterflies, monkeys, sloths and others. The canopy is the power plant of the rainforest and the place where most of the photosynthesis occurs. Trees of the canopy are spaced about three feet apart to capture available sunlight as well as to prevent damage from strong winds or to prevent the spread of insect pests.

D. Emergent Layer The emergent layer is exposed to the bright light of the sun and, as a result, must have mechanisms to cope with the light. Many have small waxy leaves. Insects and numerous other small creatures abound here: ants, spiders, termites and others. Many of the animals and plants that thrive here are adapted to dry conditions. Monkeys, eagles, lizards, large birds, possums, and numerous other animals are present.

SOILS OF RAINFOREST

Surprisingly, the soils of rainforests are deficient in nutrients because the decomposition process is so fast. Furthermore, the soils are rich in iron compounds that, after exposure to sunlight, hardens the soil making them impervious to the growth of plants.






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