A

Fig. 1.10A, B Original and remaining forest in 13 critical regions. A Madagascar, Atlantic coast of Brazil, West Ecuador, Columbian Choco, West Amazonian Highlands, Rondonia/Acre in Brasilian Amazonia, montane forests in Tanzania/Kenya, Eastern Himalaya, Sinharaja Forest in Sri Lanca, Malaysian peninsula, NW-Borneo, Philippines and New-Caledonia, and in three particularly critical regions: B Madagascar, Atlantic coast of Brazil and West Ecuador. (After data of Myers 1988)

Fig. 1.10A, B Original and remaining forest in 13 critical regions. A Madagascar, Atlantic coast of Brazil, West Ecuador, Columbian Choco, West Amazonian Highlands, Rondonia/Acre in Brasilian Amazonia, montane forests in Tanzania/Kenya, Eastern Himalaya, Sinharaja Forest in Sri Lanca, Malaysian peninsula, NW-Borneo, Philippines and New-Caledonia, and in three particularly critical regions: B Madagascar, Atlantic coast of Brazil and West Ecuador. (After data of Myers 1988)

Using somewhat different definitions of tropical forests, Jacobs (1988) arrives at the following figures for the annual destruction:

• tropical rainforest in a narrow sense: 0.15 x 106km2 per year;

Unfortunately no significant improvements have been achieved to date on this tragic situation documented in the late 1980s. For example, in Brazil the Atlantic rain forest is now reduced to 7.5% of its original area (Myers et al. 2000), the Amazon area in the year 2004 experienced the highest deforestation rate ever and only 16% is still unharmed (Fearnside 2005). The major remaining areas covered with wet tropical forest are in the Zaire basin, in West Brazil and Amazonia, in the Guayana highlands and in New Guinea.

Some important global problems relate to the destruction of tropical forest with regard to

• the CO2 budget of the atmosphere;

• the nutrient balance;

• biodiversity, the first two and the last of which are also causing considerable public anxiety.

Scientifically, the effects on CO2 budgets remain a subject of debate because it is not clear whether alternative CO2 fixation processes in terrestrial ecosystems will offset or even over compensate reductions due to loss of forest. Secondary vegetation may prove to be an increasingly strong CO2 sink, and increasing CO2 in the atmosphere may be coupled to higher ecosystem productivity (Medina 1991; Plant, Cell and Environment 1991). The relations of CO2 with mineral nutrition, especially nitrogen, with guard cell sensing and transpiration and respiration, with temperature, with plant acclimation, and with the respective functions of forests and oceans as CO2 sinks are highly complex non-linear interactions in feedback networks and simple conclusions are not possible (Plant, Cell and Environment 1999).

The water balance of large areas may be severely impaired by deforestation. For equatorial forests in Amazonia it has been shown by stable-isotope techniques (see Sect. 2.5) that 50% of total incoming rainfall was lost again by evapotranspiration from the forest. Thus, deforestation not only increases total runoff of water but also disturbs recirculation, as observed in the Amazon basin, leading to lower total rainfall and more pronounced seasonality (Medina 1991).

These observations also have implications for nutrient supply: due to the rapid turnover of nutrients in tropical forests (see Sect. 3.4.4) and problems of erosion, deforestation causes major destruction of soil systems and affects nutrient budgets.

Tropical humid forests are known to be the most diverse ecosystems in the world (see Sects. 3.2.1 and 3.3.1). They are thought to support more than 50% of all plant and animal species. Deforestation leads to loss of diversity, which has not been fully assessed by census to date.

In conclusion, we are not able to predict the actual nature of all the changes that may result from the more or less complete destruction of these forests (Whit-more 1990). The theory of deterministic chaos (Sect. 3.3.3) suggests that long-term predictions about the behaviour of complex systems with feedback relations showing non-linear behaviour are intrinsically impossible (Hastings et al. 1993; Schuster 1984). However, it is equally clear that if we do not succeed in preserving these forests, we shall lose one of our greatest treasures.

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Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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