Current Rates of Deforestation:
There are several differnt ideas about the rate of deforestation.
According to some, such as a study done by Gómez-Pompa,
Vázquez-Yanes, and Guevara (1972) the rainforest is being destroyed
at a very rapid rate. They believe that this will negatively impact
millions
of species of plants and animals, most being lost before they have a
chance to be discovered. While a study done by Roger A. Sedjo and
Marion Clawson argues that evidence suggests a slower less
detrimental rate of deforestation, a view also taken by some people.
They insist that the idea of a fast deforestation is due to
unsupported and over reaching data, and that there is better data
know that gives a less dooming picture of the state of deforestation.
The tools to help observe and gather data are better now than when
the debate first started. Remote sensing devices such as the Landsat
Thematic Mapper as well as other
sensing devices will help to give a better picture of the changing
landscape. The idea of mapping the forest from space is set up in a 5
phase program. Starting with low resolution and ending with a global
monitoring project.
Though there is discrepancy over numbers, conflicting sides both seem
to agree on what is effecting the rates of deforestation. The rate of
deforestation is effected by government discussions, local farming
practices, local economy. It has an impact on many things globally
and local...such as wood for fuel and building, loss of habitat, loss
of species, and negative environmental impacts .
Ecological Complexity:
Tropical forests have an abundance of life forms and provide extreme
ecological complexity. Mulititudes of animals and plants are
competing day and night food, light, space, while often exploiting
each other and/or simultaneously protecting each other. In this
intricate
web exists an ecological equilibrium that is difficult discern into
the many coinciding inter-relationships.
Ecological complexity stems from the exceptional amounts of light,
warmth, moisture and overall favorable conditions for evolution of
the species that the tropical forest
is able to provide. Scientists hypothesize that it is the climatic
stability, with no seasonal hiatus in the form of winter each year
that allow the forest to thrive.
In contrast to the tropical forests, temperate zones are not so
successful , due to colder seasons, plant growh tapers off for
several months of each year, creating a famine that animal life must
endure.
Adaptive radiation is the throwing off new forms. These new forms can
lead to new subspecies and eventually to new species. Plants and
animals, developing in co-evolutionary accord, devise new ecological
living spaces.
Evolution works slowly. The great complexity that exists has taken
eons to develop. Tropical-forest ecosystems are most certainly the
oldest continuous ecosystems on the
planet. They have generally experienced exceptional stability and
continuity for much of their past, with opportunity for evolution to
go its creative way undisturbed. At other times, they have undergone
enough "constructivce disruption" to foster fresh
evolutionary departures.
The influence of many island territories of different sizes creates
an archipelago effect. this means that speciation is stimulated
because plant and animal communities were divided into thousands of
distinctive units and thereby promotes extreme differentiation.
When sea level drops, sometimes islands merge to form a sigle
territory, allowing their wildlife communities to mingle. This
results in greater diversity and complexity because when the seas
recede again, the prehistoric forests are split into fragments once
more, and then each separate sector follows its evolutionary path in
response to local environmental conditions and natural selection.
The cycling of mineral nutrients is central to the workings of
tropical forests. Most tropical forest soils are very old and
impoverished. An example of this is Amazonian
topsoils, which only posses minor quantities of phosphorus. The
phosophorus is chemically fixed in forms that leave it unavailable to
plants and overall the region has less than
generally needed for fertility. Also, due tue heavy rainfall in
Amazonia, the few minerals that have survived lengthy periods of
topographic stability have leeched deep into the ground. Areas in
the foothills of the Andes have high nutrient soils as do alluvial
territories
of the floodplains. These areas can be considered to offer the
fertility and drainage suitable for agriculture. In other areas of
this region, farmers would need to spend
large sums on lime and fertilizers to make the land suitable.
The fast, efficient cycling of nutrients in a tropical forests occurs
within a virtually closed ecosystem. Most of the concentration of
nutrients are found in the plant communities. This is why forest
soils have almost no exchangeable minerals such as calcium, magnesium,
potassium and phosphorus stored in them. The soils are mainly highly
acidic, infertile and un-suitable for agriculture.
Tropical trees have efficient self-regeneration systems. Few of them
depend on the wind to carry their
pollen and seeds. Seeds of trees in tropical forests generally have
little or no capacity to remain
dormant and usually survive no more than twenty-five days. Trees of
tropical forests do rely heavily on
their dispersal agents. In many cases the dispersal agents are
fruit-eating animals.
The causes and processes of deforestation:
Role of cattle raising in conversion of tropical moist forest:
Until 1975, the pasture and the numbers of beef cattle doubled in
Central America, at the expense of primary moist forests, as in
Brazil, where 80000 km2 of Amazonian forests were converted into
cattle ranches. This growth is alimented by several reasons, for
instance, the low cost of lands and labor in Latin America compared
to other countries.
The causes of land degradation along "spontaneously" expanding
agricultural frontiers in the third world:
Relating land use and global land-cover change:
Role of forest farmers in conversion of tropical forests
This is the most important factor, because these 140 millions forest
farmers not only clear the forest of all its trees but also burn the
wood. The forest then needs about 10 years to renew itself, but the
number cultivators increased, they have less space for local
migration and then this need is no more respected. Now, 105000 km2
disappear per year. A solution, the agroforestry, which provides
alternatives for forest farmers, consists in planting trees rather
than cut then down.
Dialog Summary
In 3.5, several people had comments about the implications and
perceptions of deforestation. Deforestation was discussed in terms of
its effects on subjects ranging from desertification to economics.
Rainforests were discussed, with a question posed about the possible
benefits of tree removal for forest regeneration. The general opinion
that was shared in the responses to this idea was that the delicate
nature and balance of rainforests would be harmed by excessive tree
removal. Whether due to changing the levels of sunlight and moisture
or considering the acidic soil type, the consensus was that a
rainforest would require a long time to repair if humans were to
remove trees.
Another rainforest comment was focused more specifically on Brazil
and comments from this country's government. An important point was
brought up that, as much as the U.S. might criticize other
governments for not stopping rainforest destruction, early Americans
cut down their fair share of trees as well.
A third posting focused challenged another perception, this time
about clearcutting. An argument was made was that clearcutting is not
the same as deforestation, or the complete removal of trees. It was
also argued that more trees should be used for energy or building
supplies, since it is a renewable resource. One response concurred
with this posting. Another presented counterpoints, arguing that vast
removal of trees damages water quality and delicate soil and the
disruption of a carefully balanced ecosystem. It was also brought up
that clearcutting could possibly be used, but that there remains no
organization to monitor such activities.
On a different note, genetically modified trees were discussed as one
possible aid in controlling desertification. It was brought up that
GMOs could be beneficial if engineered to live with a small amount of
water in arid conditions. However, it was also mentioned that the
current global conflict about the suitability and safetly of GMOs,
such as with biodiversity, could be a major deterrence to this idea.
One response argued that genetically engineered plants should
definitely be researched, but that we should not sacrifice
biodiversity, natural plant reproduction, or natural resilience for
entire bioengineered forests.
Land degradation due to spontaneously agricultural expanding is
severe in the third world because of the tenure regimes facing
agricultural colonists. On one hand, because of the possibility to
acquire property rights in an idle land by converting it to
agricultural use, the deforestation is strong and existing farmland
are not conserved. On the other hand, the use of less erosive farming
techniques and agricultural commodities can also accelerate the
process.
The land use is controlled by environmental factors, but also by
human activities.