NATURAL RESOURCES What are Natural Resources? Natural

NATURAL RESOURCES

What are Natural Resources?

Natural resources are sources of wealth or health produced by the earth's natural

processes. They include soil, water bodies, the deeper layers of the earth's crust and the

air surrounding earth. Natural resources also include the earth's organisms, from viruses

through mammals.

Resources can be classified as abiotic or biotic. Oxygen, water, nitrogen, rocks and soil

are all abiotic components. The organisms in the environment are the biotic component.

Some resources are essentially limitless on a human time scale. Solar energy, wind,

flowing water and tides are examples of these perpetual resources. A potentially

renewable resource is normally replenished through natural processes. White-tailed deer

and trees are potentially renewable resources. Sometimes these resources are used or

polluted at a rate greater than the earth's ability to replenish them. In such an instance, the

supply of that resource may then be considered nonrenewable.

A nonrenewable resource is available in a fixed amount. Supplies of nonrenewable

resources may be exhausted because they cannot be replaced by natural processes or at a

rate to match the demand. Nonrenewable resources often become economically depleted

before supplies are actually exhausted. As a rule, after 80 percent of the total estimated

supply has been removed and used, it becomes too expensive to harvest the remainder.

Coal, oil and fluorite are examples of nonrenewable resources in Illinois.

The species classification category contains organisms that resemble each other in

appearance and behavior. Members of a species can reproduce and produce fertile

offspring. Species diversity is the number of species present in a defined area. The

species diversity on earth is estimated to be between 40 and 80 million. Of that total, only

1.5 million species have been classified by scientists.

All organisms are potentially renewable resources. When a particular species' population

has difficulty renewing itself, it may declared an endangered or threatened species. An

endangered species is in danger of extinction. The harlequin darter and tube beardstongue

are among the state endangered species. The Indiana bat and leafy prairie clover are

federally endangered species that also live in Illinois. A threatened species is one that is

likely to become endangered in the foreseeable future. Decurrent false aster is a plant that

is both state and federally threatened. Species are classified as endangered or threatened

by two laws, the Illinois Endangered Species Protection Act of 1972 and the U.S.

Endangered Species Act of 1973. A third category is not controlled by law but by

decisions made by state and federal regulatory agencies. Species are placed on a watch

list for a variety of reasons: when there is insufficient data on the population; when the

population was endangered or threatened but now seems to have regained stability; or

when the population is threatened or endangered in one area but seems stable elsewhere.

The eastern bluebird is a watched species in Illinois.

Animal species can also be classified as either game or nongame. A game species is

hunted for sport, food, fur or another intrinsic value. The white-tailed deer is a game

species. A nongame species is not hunted. The northern cardinal is a nongame species.

Some game species are protected from hunting because the species is threatened or

endangered. The greater prairie-chicken is a game species that is protected in Illinois due

to its endangered status.

What is an Ecosystem?

The place an organism lives is its habitat. However, no single species occupies a habitat

in isolation. Habitats overlap. The species that interact within their respective habitats

make up a community. An ecosystem includes a community or communities with the

chemical and physical factors that comprise its nonliving environment. All ecosystems

must exchange energy with their surroundings. The sum of the earth's ecosystems makes

up the ecosphere.

Many complex processes contribute to the maintenance of an ecosystem. Nutrients,

elements and compounds necessary to sustain life, are recycled through the ecosystem by

a process known as the nutrient cycle. Nutrients can be organic compounds (sugars and

proteins), inorganic materials (water, carbon dioxide, oxygen, nitrate ions) and elemental

ions (iron, calcium). Many chemicals do not naturally occur in the form required by

organisms. Chemicals are constantly recycled through the living and nonliving

components of the ecosphere. These cycles include the carbon, oxygen, nitrogen,

phosphorus, sulfur and water cycles that are driven directly or indirectly by energy from

the sun.

A chemical may be part of an organism at one moment and part of its nonliving

environment at another moment. One oxygen molecule you just inhaled may have been

inhaled previously by you or your grandmother. Similarly, a carbon atom in you may

previously have been part of a plant, a mastodon or a piece of coal.

A food chain is the path that nutrients take from a producer (plant) to a primary consumer

(herbivore) to a secondary consumer (predator of herbivore) to a tertiary consumer

(predator of predator). A simple food chain cannot accurately portray the

interrelationships in an ecosystem. Another process vital to the ecosystem is the food

web. A food web, made up of many interconnecting food chains, is a closer

approximation of the natural process. As organisms interact in food webs to use and

transform energy, they form an energy pyramid.

Each link in the food chain or level of an energy pyramid is called a trophic level. All

organisms that fulfill the same role in the food web are part of the same trophic level. For

example, all producers are on one level and all tertiary consumers are on another level.

Less total energy is available for the consumers at each succeeding level because it has

been consumed and some has been released to the environment. Many species operate at

several trophic levels. A bass eating an insect may be a secondary consumer. The same

fish, minutes later, may eat a bluegill, thus acting as a tertiary consumer.

Carrying capacity refers to the greatest number of individuals of a particular species that

an ecosystem can sustain over time. The carrying capacity of an ecosystem is not static

but may vary from year to year or season to season. During a drought or severe winter,

the number of organisms an ecosystem can support will decrease. When food supplies are

plentiful, an ecosystem may support more individuals than the previous season. The

single factor in an ecosystem that limits growth, abundance or distribution of the

population of a particular organism is the limiting factor.

Why Manage Natural Resources?

A population includes all members of a species living in a defined area at a particular

time. Many things can be learned about a species by studying an entire population rather

than a single organism. For example, populations possess density, natality, mortality and

an age structure, none of which can be studied in an individual organism.

Population density is the number of animals per unit of area. Natality, or the population

birth rate, refers to the annual number of births per number of individuals. Mortality, or

the population death rate, refers to the annual number of deaths per number of

individuals. The population age structure is the distribution of individuals across various

ages.

All living things have a reproductive instinct for insuring their survival. Ecologists call

this a reproductive plan. Each organism, no matter how big or small, can be classified as

a pioneer, climax or transition species.

Organisms with a reproductive plan for a high rate of population growth are called r-

planners. They mature quickly, mate often and produce large numbers of weak offspring.

These strategies, along with little or no care from parents, usually result in few young

surviving to reproduce while many young die. Bacteria, algae, most insects, annual

plants, many fishes, some game birds, many song birds, rodents and many small

mammals are r-planners. Some fishes, for example, can lay between 1,000 and 1 million

eggs, but have a 99.9 percent mortality.

Not only do bacteria inhabit live tissue, but they are the first to invade dead tissue.

Annual grasses are usually the first plants to grow in freshly plowed fields. Algae

reproduce in puddles, ponds and swimming pools. For these reasons, these and other

organisms that are the first to colonize an area are called pioneer species.

At the other end of the spectrum are organisms whose numbers are controlled by

competition, predation and the amount of space in their habitat. They are called K-

planners because "K' is the symbol for carrying capacity. Carrying capacity refers to the

number of individuals in a given population that the habitat can support. K species have

only a few large offspring that are nurtured until they reach reproductive age. These

species include wolves, bears, cougars, wapiti, bison, most medium to large mammals

and some large perennial plants. Humans are K-planners who have, with the use of

science, learned to speed population growth. Since they evolved from and depend on

ecosystems changed by pioneer and transition species, K-planners are also called climax

species.

Because the natural world is in a constant state of change, most living things are

transition species. They fall somewhere in the range between r- and K-planners in the

number of young they bear. Their mortality rate is lower than r-planners but higher than

K-planners. In other words, some connection between reproductive and mortality rates

may occur, but no clear pattern exists. For example, some kinds of waterfowl have a 50

percent mortality rate in the first year, but others can live up to 20 years. White-tailed

deer have a high reproductive rate but also experience a high mortality rate.

A limiting factor is any single factor that limits the growth of a population in a given

ecosystem. Usually, factors such as predation, competition and disease keep a species?

birth rate and death rate in balance, thus maintaining a stable population that the

ecosystem can support. Extreme weather conditions can be a limiting factor. In 1984,

severe and prolonged cold weather and snow resulted in the deaths of many animals.

With fewer animals surviving winter, the number available to mate and reproduce the

following year was considerably less.

Changes in conditions can increase or decrease an ecosystem's carrying capacity. As a

population's size reaches or exceeds its capacity in the ecosystem, its death rate increases.

If this correction occurs suddenly, a population crash occurs. The carrying capacity for a

given population is not a fixed number, but may change as the quality of the habitat

improves or lessens.

Ecosystems are altered by species immigration and emigration. Immigrating species are

those entering an ecosystem. Emigrating species leave an ecosystem. Both immigrating

and emigrating species may indicate ecosystem degradation.

Alien, or exotic, species may be introduced to an ecosystem by immigration or deliberate

or inadvertent introduction by humans. Introduction may simultaneously have positive

and negative effects on the ecosystem. The ring-necked pheasant is one such exotic

species. A native of Asia, the pheasant has established itself as a member of Illinois'

grassland ecosystem and is a popular game bird. On the down side, pheasants compete

with the native prairie-chicken for nesting space, parasitize their nests and harass

chickens on the "booming" grounds where males call to females. The prairie-chicken is

an Illinois endangered species. The European starling is another example of an exotic

species that competes with native species for scarce resources. Without natural predators,

starlings have become successful to the point of being a nuisance.

In natural, stable ecosystems, prey species are controlled by competition between and

among species and the number of predators. Manipulation of many of Illinois' natural

ecosystems has disturbed this balance. Consequently, fish and wildlife management is

necessary to control population levels.

EXOTIC SPECIES ADVANTAGES AND DISADVANTAGES

SPECIES ADVANTAGES DISADVANTAGES

ring-necked pheasant popular game bird nest parasite

Scotch pine Christmas tree disease and dispersal

coho salmon human food source competes with native species

common carp human food source competes with native species

rusty crayfish bait displaces native crayfish,

disturbs walle

e spaw

European starling seed dispersal displaces native species,

alters natural habitat

spongy moth bird food source forest defoliation

house sparrow seed dispersal displaces eastern bluebirds

and cliff swallows

zebra mussel food source for diving

ducks

kills native mussels, encrusts

water intake pipes and other

ects in wate

garlic mustard ground cover invades forests excluding

native species

Japanese honeysuckle ornamental vine dominates forest understory

rowth

winter creeper ground cover dominates forest understory

rowth

purple loosestrife food source for shore and

wadin

birds

dominates wetland plant

communities