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.

Faktor-faktor Lingkungan

1.Abiotic facotrs

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.