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Exploring the beautiful nature of California
California Nature: Ecosystems
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Living things interact with
each other and with
nonliving factors in
ecosystems. Abiotic factors are the nonliving parts of an ecosystem. The Sun influences climate, another abiotic factor. Climate is the pattern
of weather that occurs in an area over many years.
Most life on Earth depends on energy from the Sun, an
important abiotic factor. Green plants use energy from the
Sun to make food. Other animals eat those green plants. Still
other animals eat those animals. The Sun’s energy also controls many other abiotic
factors in the environment.
Temperature is one of the abiotic factors that affects plant
growth. Plants grow best in regions that are moderate, not
too cold and not too hot. Plants also grow well when the temperature
does not change greatly. This means that daily and
seasonal temperatures are consistent. Because there are more
plants, regions with constant warm temperatures support the
greatest numbers of living things.
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Water is another important abiotic factor to
almost all life on Earth. Water helps organisms absorb nutrients
and is important in ridding organisms of wastes. More
organisms can survive in places with plenty of water.
Soil contain different minerals, such
as limestone or quartz. These minerals affect
the chemistry of the soil, such as the acidity
or alkalinity. Plants do not grow well if the
soil is too acidic or too alkaline. Farmers and
gardeners also measure the concentrations of
important plant nutrients, including nitrogen,
phosphorus, and potassium.
Like the Sun, air is also an important abiotic
factor. Humans and many other organisms
can only survive in places where the air
contains enough oxygen. Many organisms
use oxygen to help their cells release energy.
Most organisms that use oxygen can only
survive for five minutes without it before
cells begin to die. At higher elevations, the
mountain air contains less oxygen. Mountain
climbers carry oxygen tanks to help them
breathe. Some organisms can use less oxygen
than can others. The air in a particular ecosystem
determines the organisms that will
live there.
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Biotic factors are the living parts of an ecosystem. Every
organism in an ecosystem depends on other organisms
Plants and animals in an ecosystem compete with others for food or living space. Some benefit
each other by providing food, a place to live, or a way to
hide from enemies. Each species plays a different
role. Together they are the biotic factors of the ecosystem.
In ecosystems, the population of an organism
refers to all the individuals of that species that live in a given
location. For example, a scientist might study the population
of condors in California or great white sharks in the Pacific
Ocean. In a smaller ecosystem, a scientist could study the
population of frogs in a pond. A community is all the populations of species that occupy
an area. In nature, populations expand
until the biotic or abiotic factors become limiting. A limiting
factor is an environmental factor that limits how large a population
can grow. If populations get too large, competition for
resources, such as food and water, will cause some individuals
to die. |
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Limiting factors can change over time. For example, in
ecosystems that normally have plenty of rain, water can
become a limiting factor during a drought. Different factors
limit different species. Sun-loving plants do not grow well in
the shade or in dense forests. But mushrooms and forest
wildflowers will grow well in the shade.
Hawks, snakes, and many other organisms make up
California’s coastal scrub community. These communities
have many shrubs and few trees. They are accustomed
to hot, dry summers and mild, wet winters.
During summer, many shrubs lose their leaves to
conserve water. Animals living in this community
must adjust to great differences between summer
and winter water supplies.
All living things need water, but some need more water than
others. Organisms that live in sandy deserts are adapted to a
life that has little water during much of the year.
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An
adaptation is any physical or behavioral characteristic that
allows an organism to be better suited to the environment.
Cactus have waxy coverings to prevent water loss from evaporation.
Another way organisms survive in deserts is by staying
inactive during the hot, dry summers. During the brief
wet periods, wildflowers bloom, and animals gather food
before the dry weather forces them to become inactive again.
Some animals have the ability to cool themselves.
Animals living in harsh climates use shelter to protect
themselves from abiotic factors. In deserts and polar regions,
for example, frogs dig burrows to avoid the heat or cold.
All organisms need space in which to live and grow. In a
garden or a forest, plants will grow best if they do not have to
compete with other plants. Animals also need space. Some
animals defend their territories in order to protect enough
land to meet their needs for food, water, and shelter.
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