Ecological succession is the abrupt changes in the condition of the environment to which organism needs to adapt in order to survive. Some of these changes are fast and vicious that cause vast extinction of diverse organism in the biosphere. These “drastic changes” are the cause why some plants and animals suffer great loss in number and might end up to extinction of the whole specie. Some of these drastic changes are natural phenomenon such as:
a. Earthquakes
b. Volcanic eruptions
c. Landslide and cave-ins
d. Floods
e. Pollution
These natural changes are somewhat out-of-control by people and mostly brought about by disastrous natural calamities in the biosphere. A natural calamity such as volcanic eruption can wipe-out plant and animal population in an area, an ecological succession slowly takes place until finally the dilapidated area is brought back to life. People do have control over the changes in the biosphere which are brought about by their activities.
Water Pollution
This is the contamination of streams, lakes, underground water, bays, seas and oceans by substances that is harmful to living things. This commonly occurs in industrialized countries all over the world just like air pollution. The famous Rhine River which cuts through several countries from Austria to West Germany has been known as “Europe ’s largest open sewage system.”
Marine biologist will forever sadly remember the worst oil spill in the United States which occurred in Valdez, Alaska in 1989. The Exxon Valdez tanker spilled over 41 million liters of oil which killed thousands of marine organism in the waters of Valdez.
In the Philippines, five major river systems in Metro Manila and practically all rivers in highly industrialized cities like Cebu, Iloilo, Baguio and Davao are already biologically dead.
In solving this problem you must consider the major sources of pollutants in your community. Some of the causes of water pollution are:
Improper waste disposal by industries and even household
Additional harmful substance in water
Water pollution does not only greatly reduce marine vegetation and animal life along the coastline, it is also contributes to the destruction of aquatic ecosystem like coral reefs and mangroves.
Air Pollution
This is a condition where additional vile substances in the atmosphere are added that may results to damage environment, human health and the quality of life. It is caused by human activities inside homes, schools, offices, industries and cities that can spread across continent and even globally.
Air pollution is a serious problem in many countries in this era of industrialization. It is true that industrialization is a means to achieve better socioeconomic conditions. But it is also a fact that industrialization is accompanied by problems which endanger the health of the people and the lives of plants and animals.
The term smog refers to the mass of smoke or fumes containing poisonous gases and particles of various industrial wastes that blackens the horizons of a highly polluted are. Smog comes from the exhaust pipes of vehicles and from the chimneys of factories.
Smog ’s travels far and wide from its sources. Noxious gases and particulates these are small solid particles in the air released from steel and chemical plants of West Germany have been carried to as far as London, Copenhagen and Stockholm, a radius of more or less 150 kilometers. Look at the map of Europe and locate these cities.
In the Philippines, pedestrians often run into black fumes from the smoke-belching vehicles are crowded cities, whilst motorists in the suburbs see a layer of smog hanging low in the horizon of the Greater Manila Area. Recent high death rates of chickens in many poultries of Bulacan and of ducks in the towns of Pateros, Taguig and Pasig have been traced to air pollution. Sturdy plants which are used to beautify street islands and sidewalks can hardly survive in the toxic content of the air in the metropolis.
Forest Denudation
This is a phenomenon where forest soil is strip by erosion or weathering. It is also known that tropical rain forest is the most diverse terrestrial ecosystem on earth. But it only covers less than 10% of the earth ’s surface; they contain more than half of the species of organism documented worldwide.
The Philippines economy and ecology are greatly dependent on this rich ecosystem. The forest provides renewable sources of food, fiber, medicine, lumber and other wood products which keep our economy alive. They also serve many ecological functions that help conserve soil and water; replenish oxygen supply and reduce carbon dioxide in the air.
But deforestation and agricultural practices are destroying our forest at an estimated rate of 120 000 to 200 000 hectares every year. As of 1991, only 800 000 hectares of virgin forest land remain in the Philippines. If this continues we could have totally exhausted our forest resources by the years to come.
Destruction of Coral reefs and Mangroves
In coastal ecosystem coral reefs and mangroves are valuable in stabilizing the shoreline and protecting the coast from erosion. It also serves as the shelter of crustaceans and nursery ground for marine organisms. They are rich source of important products as follows;
Fuelwood and charcoal from the mangrove trees.
Food like fish, algae, shellfish and many others
Corals used as ornaments and construction materials
Aquatic organism for aquarium and curio trade
These ecosystems however are being lost due to the following activities;
Overcutting of mangrove trees and over-collection of corals and other marine organism.
Destructive fishing methods using dynamite, cyanide, and muro-ami
Siltation as eroded soils from denuded forest and abandoned kaingin are carried by runoff to the shore.
In the Philippines, only 5% of total of 25 000 square kilometers of coral reefs remain in excellent condition and in 1988 it was reported that the only around 140 000 hectares of mangrove of forest was left of the estimated 500 000 hectares in 1918.
Kaingin System of Farming
This is the process where Kaingineros burn first the forest to produce charcoals. And because of this, great tracts of land in the forest have been destroyed by kaingin method of forest farming.
Kaingineros cut down the trees, then burn smaller plants to make clearings for planting their crops. Plant materials go up in smoke instead of being decayed to human which enriches the soil. After about two years of such planting and burning to destroy coarse grasses such as cogon and talahib, the soil becomes depleted of nutrients. Thus the farmers leave the area to repeat their wasteful farming in another place.
Some abandoned farm have soil that is unproductive which is left bare and loose, lacking in organic matter because of the regular burning of plants. Like sand, the soil in abandoned clearings does not store water. When rain comes, most of the water runs off the surface instead of being absorbed by the soil. This is the reason why bare, treeless areas mean flood when torrential rains come and drought when there is prolonged dry season. There are the immediate results when man destroys the forest by the kaingin system of farming and by illegal and wasteful longing practices.
Besides destroying life and property, how else do floods and drought harm us? For one thing farmers cannot plant rice and other crops in flooded areas; you know very well that rice is a staple food in the Philippines. On the other hand, drought cause plants to dry up and die. Those that survive produce low harvest.
Acid Rain
The acid rain phenomenon is an offshoot of air pollution. Some waste gases from industries especially sulfur dioxide, react with rainwater and become acids. In the early 1980 ’s for example rain in some part of Europe had a pH value of 4.1 to 4.9 that pure water is pH7
Acid rain causes the leaves of the trees to fall; this is called defoliation from the word foliage which refers to leaves. Acid rain also destroys crops. In bodies of water, acid rain kills fish and other aquatic life.
Eutrophication
This phenomenon is an offshoot of water pollution which is even worst. It happens when some waste materials thrown into a body of water, add nutrients to the water; detergents for example may consist of as much as 40% phosphates.
And runoff from the farmlands utilizing excessive amounts of fertilizers contains phosphates and nitrates. These two substances make the water so rich that algae and other water plants grow abundantly. After some time, these plants die and sink to the bottom. Their decomposition may use up the oxygen gas dissolved in the water, resulting to death of aquatic life primarily due to lack of oxygen or “suffocation.”
References ; Wikipedia, the free encyclopedia , Science and Technology by Lilia M. Rabago Ph. D , Crescensia C. Joaquin Ph.D, Catherine B. Lagunzad , PH. D, Encarta
, Environmental Issues that is Caused by Human Activities in the Biosphere www.ozeldersin.com bitirme tezi,ödev,proje dönem ödevi