Environmental impacts on forests
- Effect on soil.
- The sustainable productive potential.
- The observed boost in agricultural production following a forest cover.
- Effect on water.
- The effect of trees
- The myth that forests act like a sponge.
- The lowering of water tables.
- Effect on air.
- The process of photosynthesis.
- The role of wood products in the global carbon cycle.
- Effect on wildlife and people.
- Main difference between forests and other terrestrial ecosystems.
- The oceans - the base of the biological pyramid.
There is considerable debate over de?nitions for the word ?forest' and even for ?tree.' Most vegetation types fall clearly into the categories of forest or nonforest, but there is dispute at the margins. A similar debate rages over the classi?cation of forests into natural and arti?cial types. On the one hand, we could say that totally natural forests do not exist. There is probably not a single hectare of the earth's surface that has not been modi?ed to some extent by human activity. In some parts of the world, hominids have been a part of the ecosystem for perhaps a million years, often using ?re or browsing mammals. Peoples have introduced new species or eliminated species from every land mass, and have even modi?ed the air (which provides a tree with its most important nutrient by weight ? carbon). On the other hand, even a ?monocultural' and monoclonal plantation contains a surprising variety of adventitious species and cannot be said to be entirely arti?cial.
[...] Effect on Wildlife and People The main difference between forests and other terrestrial ecosystems is that trees have a more pronounced vertical component. In terms of the volume of space bounded by the ground and the top of the canopy, forests contain considerably more volume than all other terrestrial ecosystems combined. Within this space, there are many biological niches and an abundance of plant and animal wildlife can develop. These species are interesting because they add variety to the world, and because some of them can be useful to humans. [...]
[...] So, although forests do not greatly in?uence the total quantity of atmospheric water moved from the ocean to the land, they may well affect the quantity and distribution of rainfall on that land. The effect of trees in a particular catchment is to reduce the yield of water, not to enhance it. Two effects cause this: interception and transpiration. Interception is where the rain wets the canopy and does not reach the ground. Readers will remember when they have stood under trees in a light shower and remained dry. [...]
[...] Effect on Air It is now common knowledge that there is a connection between forestry and the enhanced green-house effect, but there is still considerable public confusion on the details. The concentration of atmospheric carbon dioxide (CO2) has been rising for the last century, leading to the concern that it will cause global warming. The evidence is overwhelming that the increase in CO2 is human-induced: the cause is both combustion of fossil fuels and deforestation (historically, one-third, but becoming less important). [...]