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Ethiop. J. Educ. & Sc.                                           Vol. 3 No. 1 September  2007

      Human activates have greatly reduced biodiversity of the world in various ways (IBCRa 2001). Habitat loss as humans develop land and water for agriculture, grazing livestock, and unsustainable use such as draining wetlands and deforestation for agriculture land and polluting the air, soil and water through unwise use of chemical compounds such as herbicides, insecticides, etc greatly affect biodiversity (IBCRb, 2001). The devastation of forest ecosystem is also heavily continued with fast rate. As forest take up a quarter of the land surface and are immensely important for the earth’s ecological balance and hence appropriate conservation measures must be taken for sustainability of the forest resources and biodiversity in it Hauff (2002). The same analysis showed that, 15 million hectares of forest are destroyed each year. Hauff (2002) extended his analysis that, the great diversity of flora and fauna plays a vital role in global survival and yet each day 50 different species become irrevocably extinct. The consumption of fossil energy and drinking water is increasing and yet many millions of people still have hardly any access to these resources. Furthermore, desertification has immensely increased fast (Hauff, 2002). Overgrazing, over intensive cultivation, deforestation and faulty irrigation are some of the causes.

The world population is increasing by 100 million people a year, while the amount of farmland is steadily declining. Between 1991 and 1997 the area of land available and used for the production of food fell from 0.44 to 0.26 ha per head and decrease approximately 0.15 ha by the year 2050 Trittin (2002). One reason for this is desertification Trittin (2002). Particularly important are the challenges involved in the global conservation of limited resources such as land and water.  Hunger forces people to stripe away too many

valuable resources. Overgrazing, over intensive cultivation, deforestation and faulty irrigation are just some causes of desertification due to increase in human population (Hauff, 2002). Hence ensuring the future feeding of the world’s populations requires putting an end to deforestation and loss of valuable land resources. In many places equal land distribution the so-called access to land is a basic requirement for viable long term use of land. Harmful substances in land and water become time bomb for future generations who need theses resources available outside mild climate zones are too scarce to sustain development. As many people concentrate on the use of few space and resources the erosion of soil, destruction of water, vegetation and animal biodiversity affects nearly 70% of all arid regions on earth (Hauff, 2002). Tropical rain forests are important; because they harbor at least 50% and perhaps more of world’s biodiversity under threat. The original extent of tropical rain forest was 15 million square km. currently there remains about 7.5-8 million square km so that half is gone. The current rate of loss is estimated near 2% annually 100,000square km destroyed; another 100,000 degraded while there is uncertainty regarding the rate of loss and what it will be in the future, the likelihood is that the tropical forests will be reduced to 10-25% of their original extent by late twenty first century (AB, 2005). This gradually leads to losses resilience irreversibly thereby ending in desertification. The overuse of natural resources, frequently the result of need and hardship is destroying some five to seven million hectare of arable land and pasture worldwide each year. Therefore, food production will have to be more than double to supply sufficient food for the established global population of 8.5 billion in 2025 Trittin (2002).

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