Within the past ten thousand years or so, man has an enormous impact on the environment ever since humans learnt to hunt with weapons, to domesticate, and to farm crops we have been cchanging the enironment around us in a very significant way.
For his survival man had to explore and fight his environment. In hisn quest he has created different techniques, some of which were useful with little side effects and some which had no immediate effect but long lasting impacts. Some of these techniques are shown below.
COPPICING:
The use of wood for different application is not foreign. In the past wood has been used to make fences and furniture as well as a fuel. Now a days we have sophisicated machinery and the process of wood cutting is not much of a head ache. In the ancient time a technique know as coppicing was used to obtain lonf flexible lenghths of wood of small diameter. This technique involved the cutting of wood back near to the ground before the tree reached maturity. This allowed new stems to grow over the stump. The period of time allowed for these stems to grow depent on the specie of the tree.
Coppicing is a good conservation technique for decidious woodland and provides a variety of habitat. The coppicies are also nesting sites for some bird species such as the nightingale and the dunnock.
DEFORESTRATION:
Although deforestration has existed from the time man knew fire, it has had a greater impact on the environment from the industrial revolution to this day. The major concern is that a large number of trees are cut yearly than are reproduced. This large removal of forest is known as Deforestration. Trees play an important part in the ecosytem, they are part of the ecosystem cycles. The reduction of trees causes an imbalance in these cycles. Trees are part of the wter and carbon cycle and to some extent nitrogen cycles. Trees oborb and therefore reuce carbon dioxide levels in the atmosphere through photosynthesis. Lack of trees cause an increase in atmospheric carbondioxide and a consequent global warming. And since tree preserve soil moisture and prevents it from erosion. Their lack cause fairly easy chance for erosion and loss of water moisture which mayy result to desertification of the area. Apart from this medicine reaserchers are concerned with the loss of possible cures, keeping in mind the fact that so far many medicines such as quinin have been discovered from forests.
Governments world wide have looked into the matter and exercise regulation on the amount of trees that can be cut yearly . Many companies have taken an approach in the matter as a method of advertisement as well as collaboration to stop furher deforestration and somehow observed the rule of 'Cut one tree plant two.' This has helped to bring a come back to some forests.
DESERTIFICATION:
Increasing human population exercise pressure on the environment and the ecosystem. The need for man to have sufficient food for his survival has introduced sophiscated technology in the field of agriculture Though food is now plentiful than it was some decades ago new problems have arisen. Poor soil management has led to servere land degradation which turns semi arid regions into deserts, a process known as desertification.
Increasing human population is not the only cause of desertification, it is also linked to climatic factors, Prolong period of droughts make plant regeneration difficult. Although the spread of desertification can be haulted this is not possible in a short time. In a long period of time with the proper machinery and techniques desertificated areas can be brought to agricultural prodcutivity. Such programmes have enabled agriclture to survive in desert areas such as Egypt and Saudi Arabia.
EUTROPHICATION:
Eutrophication is a natural process during which the concetration of salt builds up in water bodies. It is the artificial enrichment of these salts that pose as a prolem. Water are artificialy enriched through leaching and when excess fertilisers are washed off from farm lands. Although the Phosphorus, Nitrogen and Potassium found in fertilisers are not responsible, the trace elements in the fertilisers are. The ireased salt concetration provides a good breeding ground for green blue bacteria, which flourish forming dense populations known as Algal blooms. The density of this population increases to the extent that very little light if any at all can penetrate below th surface. Lack of sufficient light causes the alage at the bottom of the surface to die off. Thses are decomposed by saprobiontic bacteria, the decomposition of these dead organisms caue biochemical oxygen demand, resulting to deoxigenation of all the water below the surface as a consequent all the aerobic life in the lower regions die off.
Realise of sewage into water bodies may result to eutrophication and governement around the world in particular the United Staes of America have put regulations on the release of sewage into water bodies.
RECLAMATION:
Reclamation, term applied to the utilization and improvement of water and land resources for agricultural and other purposes, through irrigation, drainage of tidal marshes, restoration of strip mine areas, and other construction activities.A] RECLAMaTION OF COASTAL REGIONS:
Reclamation of coastal areas is also possible where offshore or tidal marshlands are covered by shallow water. Construction of ditches followed by artificial drainage of land between dikes and the natural coastline has been practiced in many countries to reclaim land for agricultural use. The most successful reclamation efforts of this kind were undertaken along the Zuider Zee in the Netherlands. Since land reclaimed from the sea contains a considerable amount of salt, fresh water has to be applied to the surface to wash out the excess salt and carry it away by drainage water.B] RECLAMATION OF DERELICT LANDS:
The lands that were previously used for industrial and manufacturing services are usually left heavily polutted with waste related with these industries and heavy metal ions. This make plant growth difficult. Reclamation of these lands make them safe, aesthetically pleasing and if possible bring them to productive use. The process of reclamation involve the analysis of the factor preventing growth and finding the best remedy. Although the process of reclamations are coastly they are worth while trying.Reclamation projects are not without potential harmful effects on the environment. Application of fertilizers and other chemicals on irrigated land increases the salt content of the soil and of the water returning to the source of irrigation, for example, into a river. If the water of a river is used extensively for irrigation, its salt content will increase downstream. By 1970 the salt content of the Colorado River had reached an unacceptable level.