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Ecosystems act as resource producers and processors. Solar energy is the main driving force of ecological systems, providing energy for the growth of plants in forests, grasslands and aquatic ecosystems. A forest recycles its plant material slowly by continuously returning its dead material, leaves, branches, etc. to the soil. Grasslands recycle material much faster than forests as the grass dries up after the rains are over every year. All the aquatic ecosystems are also solar energy dependent and have cycles of growth when plant life spreads and aquatic animals breed. The sun also drives the water cycle.
Our food comes from both natural and agricultural ecosystems. Traditional agricultural ecosystems that depended on rainfall have been modified in recent times to produce more and more food by the addition of extra chemicals and water from irrigation systems but are still dependent on solar energy for the growth of crops. Moreover, modern agriculture creates a variety of environmental problems, which ultimately lead to the formation of unproductive land. These include irrigation, which leads to the development of saline soil, and the use of artificial fertilizers eventually ruin soil quality, and pesticides, which are a health hazard for humans as well as destroying components vital to the long-term health of agricultural ecosystems.
To manufacture consumer products, the industry requires raw materials from nature, including water, minerals and power. During the manufacturing process, the gases, chemicals and waste products pollute our environment, unless the industry is carefully managed to clean up this mess.
These are minerals that have been formed in the lithosphere over millions of years and constitute a closed system. These non-renewable resources, once used, remain on earth in a different form and, unless recycled, become waste material.
Non-renewable resources include fossil fuels such as oil and coal, which if extracted at the present rate, will soon be totally used up. The end products of fossil fuels are in the form of heat and mechanical energy and chemical compounds, which cannot be reconstituted as a resource.
Though water and biological living resources are considered renewable. They are in fact renewable only within certain limits. They are linked to natural cycles such as the water cycle.
- Freshwater (even after being used) is evaporated by the sun’s energy, forms water vapour and is reformed in clouds and falls to earth as rain. However, water sources can be overused or wasted to such an extent that they locally run dry. Water sources can be so heavily polluted by sewage and toxic substances that it becomes impossible to use the water.
- Forests once destroyed take thousands of years to regrow into fully developed natural ecosystems with their full complement of species. Forests thus can be said to behave like non-renewable resources if overused.
- Fish are today being over-harvested until the catch has become a fraction of the original resource and the fish are incapable of breeding successfully to replenish the population.
- The output of agricultural land if mismanaged drops drastically.
- When the population of a species of plant or animal is reduced by human activities, until it cannot reproduce fast enough to maintain a viable number, the species becomes extinct.
- Many species are probably becoming extinct without us even knowing, and other linked species are affected by their loss.