ECOLOGY:
The Study of Ecosystems
Ecology (from
the Greek oikos meaning "house" or "dwelling", and logos
meaning "discourse") is the study of the interactions of organisms
with each other and their environment. The hierarchy. Define each of the
following. species ~ population ~ community ~ ecosystem ~ biosphere Ecology is
a SCIENCE, not a sociopolitical movement (e.g., environmentalism). The
Ecologist engages in the hypothetico-deductive method to pose questions and devise
testable hypotheses about ecosystems. Often, this involves the generation of
complex mathematical models to simulate ecosystems. These models represent
idealized systems to which real systems can be compared for their predictive
value. Sometimes, when a very large scale project is logistically impossible to
perform, a computer model is used to predict expected results. (Allee; 1949)
An
ecosystem consists of
*
biotic components - the living organisms
*
abiotic components - non-living factors, such as light, temperature, water,
nutrients,
topography, etc.
Environmental factors
1.Abiotic factors
Abiotic facotrs are the non-living components of the ecosystem. The
chemical, geological factors like soil, minerals, rocks and physical factors
like temperature, wind, water, sunlight are defined as abiotic
factors. The abiotic factors effect the ecosystem and play a vital role in
the biology of the ecosystem. The abiotic facts factores also include light,
acidity, radiation, humidity, temperature and all organic and inorganic components
of the ecosystem. The quantity of the abiotic components present in the
ecosystem is known as 'the standing stage'. The biotic components of the
ecosystem which includes the plants, animals and microbes interact and are
dependent on the abitoic factors.
Soil - Edaphic Factors
The edaphic factors are the abiotic factors with respect to soil.
These factors include
·
Soil texture
- The texture of the soil is variable from particles like clay to
larger particles like sand. Sandy soils are suitablke for growing plants and
are well aerated and are easy to cultivate. Sandy soils cannot retain much
water and contain few nutrients required for plant growth.
·
Soil air - Soil
air is the spaces between the soil particles where it is not filled with soil
water. The soil air determines the firmness of the soil.
·
Temperature of soil
- Temperature of the soil is an important factor, temperature of soil
below 30cm is said to be constant but there are seasonal variations. The
decaying caused by decay-causing microorganisms is low at lower
temperature.
·
Soil water
- Soil water is classified into three types - capillary water, hygroscopic
water and gravitational water.
·
Soil pH
- pH of the soil affects the biological activity in the soil and
certain mineral availability. The pH influences the growth and development of
plants.
·
The organisms and the
decaying matter in the soil is known as soil solution and it increases the
fertility of the soil. (bio.edu;2005)
Light
Light is the primary source of energy to almost all ecosystems. The light
energy is used by the heterotrophs to manufacture food by the process of
photosynthesis by combining together other inorganic substances. The factors of
light like its quality, intensity and the length of the light period play a vital
role in an ecosystem.
·
The quality of light affects the aquatic
ecosystems, the blue and red light is absorbed here and it does not penetrate
deep into the water. Some algae have specialized pigments that absorbs the
other colors of light.
·
The intensity of light depends upon the
latitude and the season of the year. During the period from March to September
the Southern Hemisphere receives less than 12 hours of sunlight while it
receives more than 12 hours of sunlight during the rest of the year.
·
Some plants flower only during a certain
time of the year. One of the factors is due to the length of dark period.
Depending on the intensity of light the plants are classified as short-day
plants (Example Chrysanthemum sp., Datura stramonium etc.)
Long-day plants (Examples - Spinach, barley, wheat, radish, clover, etc.)
Day-neutral plants (Examples - Tomato, maize, etc.)
Temperature
Temperature influences the distribution of plants and animals. The occurrence
of frost is an important to determine the distribution of plants as most of the
plants cannot prevent freezing of their tissues. Below are a few examples of
the effects of temperature in plants and animals:
·
The blooming of flowers either in the day
or night is due to the temperature difference between day and night.
·
Some biennial plants germinate during
spring or summer this is known as vernalization.
·
Some fruit trees require cold temperature
so as to blossom in the spring.
·
Animals have a clear distinction between
being cold blooded or warm blooded.
·
Seasonal migration is seen in some
animals.
Water
Habitats of animals and plants vary widely from aquatic environments to the dry
deserts. Water is essential for life and all the biotic components of the
ecosystem are directly dependent on water for survival.
Based upon their
water requirements plants are classified as:
- Hydrophytes (Example - Water
lilies)
- Mesophytes (Example - Sweet
pea, roses)
- Xerophytes (Example - Cacti,
succulent plants)
Land animals are prone
to desiccation and these animals show various types of adaptations to this.
Some of the adaptations seen in terrestrial animals are:
·
Body covering which limits loss of
water.
·
Some animals have sweat glands which are
used as cooling devices.
·
The tissues of some animals like camel are
tolerant to water loss.
·
Some insects are said to absorb water from
the water vapor directly from the atmosphere.
Wind
Air currents or winds are a result of interaction between expansion of hot air
and convection in the mid latitudes. This complex interaction influences the
earth's rotation and results in a centrifugal force which lifts the air at the
equator. Some of the effects of wind are:
·
Winds also carry water vapor; this
may undergo condensation and fall in the form of rain, hail or snow.
·
It also helps in dispersal pollen grains
of some plants and also in dispersal of insects.
·
Wind erosion also leads to dispersal of
topsoil.
Atmospheric Gases
Atmospheric gases like
oxygen, nitrogen and carbon dioxide:
·
All organisms require oxygen for
respiration.
·
Carbon dioxide is used by green plants to
make food by the process of photosynthesis.
·
Nitrogen is necessary for all plants and
atmospheric nitrogen is fixed by nitrogen fixing bacteria through the action of
lightening.
Topography
Topography is the landscape shapes which is determined by the aspects of slopes
and elevations. Topography gives a variety to the ecosystems. For example: The
grassland topography is varied like hills, prairies, cliffs, low lying areas
etc, which gives variability to life forms.
- The aspect of the direction of
the land facing also varies as the land facing towards the south or the
sun ar hotter and drier than areas in the north, which are away from the
sun.
- Slope of on areas is also
important as water may run downhill and may soak in ground which
makes it available for plants. The areas in the southern part with slopes
will be much be hotter and drier than the northern areas with
slopes.
Climate
Climate of a region includes the
average rainfall, temperature and the patterns of winds that occur. Climate is
one of the most important abiotic factors of an ecosystem. (bio.edu;2005)
·
Temperature of an area and the
precipitation factor determines whether the region is grassland or a
forest.
·
The rainfall an area receives influences
the productivity of the area and the types of plants.
·
For example: The climate in a grassland
ecosystem is dry and hot during the spring and summer and is cool and cold
during the winter.
·
Precipitation in winter is snow rather
than rainfall. During summers, more water is evaporated from the grasslands
making the region deficient of moisture.
2.Biotic factor
Biotic factor is any living component
that affects the population of another organism, or the
environment. This includes animals that
consume the organism, and the living food that the organism consumes. Biotic factors also
include human influence, pathogens and disease outbreaks. Each biotic factor
needs energy to do work and food for proper growth.
Producers
A producer is an organism that makes it’s own
food from light energy or chemical energy. Most green plants that are
one-celled organisms like slime molds and bacteria are producers. Producers are
the base of the food chain.
Here is a List of Producers: bamboo,
banana tree, rubber trees, cassava, orchids.
Consumer
Consumer is a living thing that eats other living things to stay alive.
It cannot make it’s own food like a producer but relies on producers for their
source of food. There are more Primary Consumers then Secondary Consumers. Here is a list of primary
consumers: Colobus Monkey, sloth,
most bats, humming birds, bees,
lemurs, marmosets.
Secondary Consumers
These Predators have very unique adaptations, for example the Orb-Weaving
Spider found along the coast has a web so thick and strong, the web can take
down a normal sized bird. Also the Boa constrictor can strangle a human. These
adaptations help these secondary consumers able to hunt and survive in the
forest. Here is a list of Secondary Consumers: Anteater, spiders, scorpion, jagua, snakes, tigers, lion.
Decomposers
They may look like they don’t do a thing but decomposers are the most
important kind of species. All of the decomposers team up and work together to
decompose plant matter. For example to decompose a log you would have termites
eating it so eventually their wouldn’t be any fallen branches on the ground to
rot, or any organic litter. So as you can see the decomposers are very
important. Here is a list of Decomposers: earthworms, fungi, termites, bacteria, protozoans.
Hubungan
Antar Faktor Lingkungan
Dalam
kenyataannya telah dipahami bahwa faktor-faktor lingkungan saling berinteraksi
satu sama lainnya sehingga sangat sulit untuk memisahkan pengaruh hanya dari
satu faktor lingkungannya. Meskipun demikian, karakteristik mendasar dari
ekosistem akan ditentukanatau diatur oleh komponen abiotiknya. Pengaruh dari variabel
abiotik ini akan dimodifikasi oleh tumbuhan dan hewan, misalnya terciptanya
perlindungan oleh pohon meskipun sifatnya terbatas. Faktor-faktor abiotik merupakan
penentu secara mendasar terhadap ekosistem, sedangkan kontrol faktor biotik
setidaknya tetap
menjadi penting dalam mempengaruhi penyebaran dan fungsi
individu dari jenis makhluk hidup.
Organisme
hidup bereaksi terhadap variasi lingkungan
sehingga hubungan interaksi tersebut akan membentuk komunitas dan ekosistem
tertentu, baik berdasarkan ruang maupun waktu.
Application
of Ecological
Concepts
and Principles
Maintain or
emulate natural ecological processes.
Natural ecological processes shape ecosystems and should be
maintained where possible; this includes disturbance regimes, hydrological
processes, nutrient cycles and biotic interactions that also shape evolutionary
processes. Maintaining ecological processes helps ensure that dynamic natural
ecosystems continue to function and can promote ecological resilience. Natural
ecological processes (both biotic and abiotic) should be continued, where
practical, by minimizing human interference. Where interference occurs, human
actions should try to emulate those processes. For example, society no longer
tolerates some types of disturbances, such as wildfire, where valued timber
resources could be damaged or human property or life could be threatened. Yet
wildfire is one of the key natural disturbances for most terrestrial ecosystems
in B.C.’s interior. In these cases, emulating disturbance regimes through human
actions, like forest harvesting, becomes a necessary surrogate. To be most
effective, these practices should emulate the natural pattern of leave patches
and dead wood as well as removing the fibre that would have been lost to
naturally occurring fire. Restoring fire in the ecosystem through the use of
prescribed fire is an important tool but may not be cost-effective or
appropriate for many ecosystems in B.C. Other examples of perturbations to
natural processes include the regulation of water flows by dams constructed to
control floods or provide water for irrigation in the drier parts of the year.
The release of water at critical times such as during fish migration can help
mitigate these downstream impacts. (Vold and Buffett; 2008)
Manage towards
viable populations of native species.
Maintaining viable populations of all native species helps
ensure that extinction thresholds are not reached. Most thresholds become
apparent at a point where it is too late to intervene. Therefore providing
habitats that sustain populations well above minimum viable populations lessens
the risk of extinction. It is generally more expensive to recover a population
that is threatened or endangered than it is to avert population collapses
caused by crossing threshold levels. (Vold and Buffett; 2008)
Providing viable populations of a species well distributed
across its natural range (or across the appropriate environments dictated by
climate changes) helps ensure that genetic variability within populations is
conserved. This may be particularly important given evolving conditions, such
as climate change that can affect a species. The best strategy to “keep common
species common” is through coarse-filter approaches that represent native
ecosystems in protected areas while encouraging management practices in the
surrounding matrix that maintain the composition, structure and function of
natural ecosystems. These efforts will help ensure that natural patterns and
abundance of habitat and associated native species remain viable.
Set objectives
and targets for biodiversity in plans.
Managing by objectives is key to conserving biodiversity. If we
don’t know “where we want to go”, how can we assess success or failure? For
example, at the strategic level, in order to keep common species common and
prevent loss of native species, three broad objectives could include:
• representing the range of natural ecosystem types in
protected areas;
• providing the amount and distribution of habitats important
to sustain native species; and
• ensuring that the abundance and distribution of native
species are not substantially reduced
by human activities.
Measurable indicators (such as the abundance of an indicator
species) need to be developed in order to monitor whether management objectives
are being attained and provide needed “red flags” in situations requiring
corrective action. Forest certification systems generally include the
specification of criteria and indicators, as well as measurable targets,
including those for biodiversity conservation, in order to facilitate
monitoring and reporting, and to promote continuous improvement. Objectives,
indicators, and targets for biodiversity should be documented in sustainable
management plans that support resource use activities. Monitoring has to be an
integral part of the planning process. Implementation monitoring assesses
whether the targets are being achieved. Effectiveness monitoring assesses
whether the targets support the objectives and, if they don’t, provides insight
on how the targets should be adjusted. (Vold and Buffett; 2008)
DAFTAR PUSTAKA
Allee, W.; Emerson, A. E., Park, O.,
Park, T., and Schmidt, K. P. (1949). Principles of Animal Ecology. W. B.
Saunders Company. ISBN 0721611206.
Bio.edu/ecology/lecture/lec03_climate.2005.pdf
Vold, T. and D.A. Buffett (eds.). 2008. Ecological Concepts,
Principles and Applications
to Conservation, BC. 36 pp.
