Deforestation
INTRODUCTION
There are increasing concerns over the fate of the world's forests and the role of
deforestation in global warming. This article takes a critical look into the issue.
We start by giving an overview of statistics regarding forestry, narrowing down on
rainforests in particular, and then proceed to examine some of the usual arguments.
Finally, we examine the unclear factors in the equation and formulate a conclusion
about the current state of the world's forests, as well as the debate itself.
Global Warming as a whole is discussed at length in another section, so this study
just looks into the effects of deforestation on global warming, not the effects of
global warming on forests. This allows isolating the theories without being forced
to constantly branch back and forth between the two sections while reading.
FOREST STATISTICS
According to United Nations statistics, the total forest coverage of our planet is
currently 3870 million hectares. Of this amount 95% are natural forests and 5% are
forest plantations. Approximately 47% of forests are located in tropical areas, 9%
in the sub-tropics, 33% in boreal zones, and 11% in temperate zones. The 47% cover
of the tropics is further divided into 28% for the actual rainforests, 11% for the
moist deciduous forests, 5% dry forests, and 4% tropical mountain forests.
About 58% of the world's rainforests are located in South America, with most of it
in Brazil. Africa's rainforests count for 24%, and 17% are located in the southern
parts of Asia. In contrast, nearly all temperate and boreal forests are located in
Europe/Russia and North/Central America. This also applies to mountain forests.
The Russian Federation actually has a larger forest coverage than Brazil, with 22%
of the world's forests while Brazil only has 14%. It's worth noting that densities
are different in these areas. Total forest biomass is estimated around 420 billion
tonnes, of which 27% is in Brazil alone; Russia has 11,8%. South America has about
35% in total, Africa has 16,8%, Asia 10,7%, Europe 14,5% and North/Central America
12,3%. Coverage is more important than biomass for this study, however.
RATES OF DEFORESTATION
Deforestation is in general only a problem in the developing world; the forests of
the developed world are in fact spreading, thus lowering the overall deforestation
rates. This is why we narrow down on rainforests, ignoring the developed world. It
is clear that the developed world imports wood from third world countries though.
The United Nations calculate that the current global rate of deforestation is 14,6
million hectares annually, and the rate of re-growth is 5,2 million hectares; thus
net annual change is -9,4 million hectares. 3,7 million of this affects the Amazon
rainforest, and 5,3 million affects Africa. Deforestation rates have been dropping
for the last 20 years, although older numbers are not as exact as the new ones.
While these numbers certainly seem large, simple calculations against total forest
coverage give us coverages of 628,5 million hectares and 303,5 million hectares in
South America and Africa, respectively. Using a linear rate of deforestation, this
means that it will take 170 years for the Amazon rainforest to be chopped off, and
57 years to clear Africa. This is certainly more than the green estimate, 30 years.
For the sake of curiosity, if we expand the same calculation to all of the world's
forests, we get a result of 412 years. This is only worth noting because the green
activists have sometimes been known to claim even rapid global deforestation.
From these numbers we can immediately conclude that the Amazon rainforest isn't in
any danger in the near future; African rainforests are in at least moderate danger,
however. Thus conservation efforts should be directed into Africa, while education
in forestry and uncorrupted government policies are enough for South America. Note
that Africa's rainforests are however among the least developed in the tropics.
It is not clear how much of the rainforests we can afford to lose before there are
serious side-effects, but it appears likely that by the time such effects begin to
manifest themselves, the laws of supply and demand step in and make plantations so
profitable that most wood will be harvested from them instead of natural forests.
12% of the world's forests are currently protected, with North/Central America and
South America leading the way with 20% and 19% of the total, respectively. African
and Asian rainforest areas show quite low levels of protection (only 8% in Central
Africa for example). In addition, almost 90% of the forests in developed countries
are managed; the equivalent number for developing countries is only about 6%.
WRI CRITICISM
The World Resources Institute has published a paper questioning some of the points
made in the FAO report (which is the basis of this paper). WRI's sympathies are on
the side of the green movement but it should be noted in their favor that at least
they do not lie. They agree with the results of the UN research, but question some
of the interpretations of the data. It is worth looking over their arguments here.
WRI states that the report obscures some important regional numbers; deforestation
rates have increased in tropical Africa, remained constant in Central America, and
declined slightly in tropical Asia and South America. Eventhough this can actually
be considered further evidence that only African rainforests are really threatened,
it does highlight the importance of looking more carefully at the regional data.
The UN numbers do not differentiate between forest plantations and original forest,
which is one of the main sources of WRI criticism. Personally, I find this strange;
when there are more forest plantations available, less primary rainforest needs to
be cut down, so in my opinion it's correct not to differentiate between them.
WRI also makes a point of the fact that some of data behind the UN research is not
perfect, which seems strange because they at the same time admit that FAOs data is
the best there is. Why make a point of something like that when it also means that
what ever alternatives WRI can provide can't be even as good as the UN data? Looks
like this is actually brought up just to note that more research money is needed.
CAUSES OF DEFORESTATION
Deforestation is caused by a number of factors, including farming, mining, logging,
fuelwood gathering, air pollutants, tree diseases, insects, wildfires, storms, etc.
The data regarding the relative influence of each factor is surprisingly difficult
to find, in part because making such assesments is itself very difficult.
There is a general perception among scientists that agriculture is the main factor
in many areas, such as the Amazon. The World Resources Institute estimates that it
is responsible for 60% of the total deforestation rate. The impacts of logging and
mining are also significant, but not as important as the impact of farming.
The influences of non-human factors vary widely by area and season; the effects of
wildfires and storms are episodic (and usually connected to El Niņo), but at times
account for several million hectares per year. Pollution is often cited as a cause
of defoliation, but there is no direct evidence for this; we do not even know what
a "normal" level of defoliation should be. Insect pests and plant diseases are the
primary factors in many areas, but their influence is also mostly seasonal.
More research is clearly needed in this area before conclusions can be reached. It
is also necessary to examine the rainforests in the Amazon, Africa and in southern
Asia separately because the regional causes of deforestation may differ greatly.
GLOBAL WARMING
Approximately 313,5 Gt of carbon dioxide is exchanged annually between the surface
and the atmosphere; oceans account for 182 Gt, natural terrestrial sources for 123
Gt, and human actions for 8,5 Gt. Natural sources appear to take in a bit more CO2
than they release, amounting to 5 Gt; that leaves a small positive trend of 3,3 Gt.
Forests account for about 80% of the natural terrestial exchange, i.a. 98 Gt.
The main fear regarding deforestation is that when the trees are burned / rot, the
CO2 stored in them gets released back into the atmosphere. World's forests account
for 1200 Gt worth of carbon stocks, which is just above half of the carbon dioxide
in terrestrial vegetation and soil. Boreal forests account for 26%, while tropical
and temperate forests account for 20% and 7%, respectively. Within boreal forests,
80-90% of the carbon is stored in soil; in rainforests, 50% is in the vegetation.
While it is correct that rainforests produce lots of oxygen through photosynthesis,
they consume as much as they produce in the decay of organic matter; this explains
why concerns are directed at the carbon stocks instead. Even green activists agree
on this, so it is incorrect to think of Amazon as the "Lungs of the Earth". Oceans
are responsible for an overwhelming majority of the world's oxygen production.
It is worth noting that even desert, tundra, agricultural area, wetland, temperate
grassland and tropical savannah account for 5-10% carbon stocks, while rainforests
account for 20%, so no matter what rainforest is turned into through deforestation
it's very likely that almost half of the carbon actually stays in the area. IPCC's
estimate, 2.0-2.4 Gt a year, fits these factors well, so the figure looks valid.
It is also interesting to note that while all terrestrial systems in total contain
about 2,200 Gt of carbon stocks, oceans are estimated to contain reserves of about
40,000 Gt. In my opinion, this suggests that even a small change in the oceans can
easily nullify everything humans could do, although CO2 moves slowly in the oceans.
Many reports also suggest that we do not yet understand the workings of the oceans'
carbon cycle very well, which in light of these numbers looks rather worrying.
BIODIVERSITY
It is believed that deforestation and other human activities are causing damage to
biodiversity. However, the research data behind this is far from comprehensive; we
can not say with any level of certainty, how many species are really going extinct.
We don't even have a common way of defining what "biodiversity" means; researchers
tend to define the term on emotional grounds, based on their personal interests in
the field. Nevertheless, it appears that at least some species are being lost.
The loss of biodiversity has been greatest in developed countries, not in tropical
areas as one might expect. This is because of the developed world's usual tendency
to harness all available grazing areas to the farming of only a few useful species.
The overall loss has been incredibly low though, even in the developed world.
Environmental activists tend to direct attention to well-known species rather than
the situation as a whole; these animals are not necessarily all that important, in
terms of the global gene pool. This undermines the conservation efforts because so
much of the resources are again directed away from the most important targets.
Losing a species is not always a disaster, eventhough extinction rates tend to add
up. Some extinctions occur naturally, as part of the natural order of things. Most
species are derived from other species, so their genetic structure is often pretty
much the same; even small differences can account for large variations though.
In the near future, the importance of rainforests as sources of medicine and other
benefits is likely to diminish, through the arrival of genetic and nano-technology.
It is important not to lose sight of future scientific progress in eco-matters. We
can't rely on future progress of course, but history does demonstrate the pattern.
DEBATE TOPICS
Based on traditional economic models, when resources go scarce, prices go up. This
would result in increased prices, and spreading of forest plantations. For example,
China has become an important importer of wood in the recent years, because of its
economic growth and lack of forests. Perhaps not surprisingly, it's also the world
leader in forest plantation coverage. In Europe / America, early settlement caused
widespread damage, but as methods of forest management improved, deforestation was
ultimately turned into increase in forest coverage. There is already a discernible
global trend toward forest plantations, which is expected to gain more momentum.
Anti-green activists often say that wildfires are natural in rainforests, but this
can't be true because by definition of the word, rainforests are extremely wet and
humid places; thus fires could only rage if the forests dried up. However, there's
a zone of dry tropical forest surrounding rainforests, where wildfires are natural
and necessary. Much of the alleged burning of rainforests is actually taking place
in this savanna-like area, rather than right in the middle of lush rainforest.
There seems to be considerable evidence that not even nearly all of the rainforest
soil turns to wasteland after the trees have been cut off; the forest demonstrates
remarkable ability to regenerate in many areas, filling up abandoned logging sites.
Apparently only 8% of rainforest soil in the Amazon is classified as having a high
erosion risk, i.a. would not grow back very fast. Biodiversity in re-growing areas
and secondary forests is often reported as even higher than in the primary forest.
The enormous estimated rates of biodiversity loss are very controversial; the base
of the calculations is the so-called species-area curve which is a model developed
for estimating the population sizes of islands. Basically, this model assumes that
each species only exists in a single, very tiny area, and will not move even if it
is threatened by extinction. This can be true for an island considering that water
is a rather inhospitable place to move into, but not for large forest regions.
UNCERTAINTIES
The time frame of the United Nations' study was only 20 years, with extensive data
available mostly just for the last 10 years. This leaves one wondering whether the
time period is long enough to establish actual trends. There is also no attempt to
calculate the original maximum coverage of the rainforests, which seems disturbing
because such numbers would obviously be needed to determine the total reduction in
rainforest coverage. This may be included in the deforestation estimates though.
It would be quite useful to have a diagram about the deforestation rates since the
start of the process, but one is apparently not available. What we do know is that
there was a massive increase in deforestation during 1950's; coupled with advances
in logging technology, this can be considered the starting point of the process.
There have been massive forest fires during the past decades, but it was not clear
from the study whether these have been included in the deforestation figures or if
they were left out, under the assumption that such areas would grow back naturally.
Wildfires / storm damages are estimated to account for several years worth of wood
usage so this would clearly be an important factor in the calculations. The report
does however state that the damages of wildfires and storms are quite difficult to
estimate because records of such events or associated losses are usually not kept.
In many instances deforestation means turning primary forest into secondary forest,
not clear-cutting as people usually seem to believe. It was not clear whether that
has been measured as deforestation in the UN report, but this seems likely because
forest is classified by the extent of tree canopy coverage within a certain area.
CONCLUSIONS
While it is clear that the primitive land usage strategies of the developing world
are wasteful and the corruption of local officials makes this even worse, there is
no reason to panic. Concerns should be directed toward Africa, not Amazon. This is
a very emotional topic for many people, but emotions must not corrupt science. One
should note, however, that this information is not intended for the general public.
As noted in the chapter introduction, it is often best to let people live in fear.
SOURCES
State of the World's Forests 2001
Food and Agriculture Organisation of the United Nations (FAO)
http://www.fao.org/docrep/003/y0900e/y0900e00.htm
Forests, Grasslands, and Drylands
World Resources Institute (WRI)
http://wri.igc.org/forests/
The Rainforest Issue: Myths and Facts
Committee for a Constructive Tomorrow (CFACT)
http://www.cfact.org/IssueArchive/rainforest.bp.197.txt
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