From Wikipedia, the free encyclopedia
Deforestation,
clearance, or
clearing is the removal of a
forest or stand of trees where the land is thereafter
converted to a non-forest use.
[2] Examples of deforestation include conversion of forestland to
farms,
ranches, or
urban use. The most concentrated deforestation occurs in
tropical rainforests.
[3] About 30 percent of Earth's land surface is covered by forests.
[4]
Deforestation occurs for multiple reasons: trees are cut down to be used for building or sold as fuel (sometimes in the form of
charcoal or
timber), while cleared land is used as
pasture for
livestock and
plantation. The removal of trees without sufficient
reforestation has resulted in
habitat damage,
biodiversity loss, and
aridity. It has adverse impacts on
biosequestration of atmospheric
carbon dioxide. Deforestation has also been used in
war to
deprive the enemy of vital resources and cover for its forces. Modern examples of this were the use of
Agent Orange by the British military in
Malaya during the
Malayan Emergency and the United States military in Vietnam during the
Vietnam War. As of 2005, net deforestation rates have ceased to increase in countries with a per capita
GDP of at least
US$4,600.
[5][6] Deforested regions typically incur significant adverse
soil erosion and frequently degrade into
wasteland.
Disregard of ascribed value, lax forest management, and deficient
environmental laws are some of the factors that allow deforestation to
occur on a large scale. In many countries, deforestation–both naturally
occurring and
human-induced–is an ongoing issue.
[7] Deforestation causes
extinction, changes to climatic conditions,
desertification, and displacement of populations as observed by current conditions and in the past through the
fossil record.
[8] More than half of all plant and land animal species in the world live in
tropical forests.
[9]
Between 2000 and 2012,
2.3 million square kilometres (890,000 sq mi) of forests around the world were cut down.
[10]
As a result of deforestation, only 6.2 million square kilometres
(2.4 million square miles) remain of the original 16 million square
kilometres (6 million square miles) of forest that formerly covered the
Earth.
[10] An area the size of a
football pitch is cleared from the
Amazon rainforest every minute, with 136 million acres (55 million hectares) of rainforest cleared for animal agriculture overall.
[11]
Causes
According to the United Nations Framework Convention on Climate
Change (UNFCCC) secretariat, the overwhelming direct cause of
deforestation is agriculture.
Subsistence farming is responsible for 48% of deforestation;
commercial agriculture is responsible for 32%;
logging is responsible for 14%, and fuel wood removals make up 5%.
[12]
Experts do not agree on whether industrial logging is an important contributor to global deforestation.
[13][14]
Some argue that poor people are more likely to clear forest because
they have no alternatives, others that the poor lack the ability to pay
for the materials and labour needed to clear forest.
[13]
One study found that population increases due to high fertility rates
were a primary driver of tropical deforestation in only 8% of cases.
[15]
Other causes of contemporary deforestation may include
corruption of government institutions,
[16][17] the
inequitable distribution of wealth and power,
[18] population growth[19] and
overpopulation,
[20][21] and
urbanization.
[22] Globalization is often viewed as another root cause of deforestation,
[23][24]
though there are cases in which the impacts of globalization (new flows
of labor, capital, commodities, and ideas) have promoted localized
forest recovery.
[25]
Deforestation in the
Maranhão state of Brazil, 2016
In 2000 the United Nations
Food and Agriculture Organization
(FAO) found that "the role of population dynamics in a local setting
may vary from decisive to negligible", and that deforestation can result
from "a combination of population pressure and stagnating economic,
social and technological conditions".
[19]
The degradation of forest ecosystems has also been traced to economic
incentives that make forest conversion appear more profitable than
forest conservation.
[26]
Many important forest functions have no markets, and hence, no economic
value that is readily apparent to the forests' owners or the
communities that rely on forests for their well-being.
[26]
From the perspective of the developing world, the benefits of forest as
carbon sinks or biodiversity reserves go primarily to richer developed
nations and there is insufficient compensation for these services.
Developing countries feel that some countries in the developed world,
such as the United States of America, cut down their forests centuries
ago and benefited economically from this deforestation, and that it is
hypocritical to deny developing countries the same opportunities, i.e.
that the poor shouldn't have to bear the cost of preservation when the
rich created the problem.
[27]
Some commentators have noted a shift in the drivers of deforestation over the past 30 years.
[28] Whereas deforestation was primarily driven by subsistence activities and government-sponsored development projects like
transmigration in countries like
Indonesia and
colonization in
Latin America,
India,
Java,
and so on, during the late 19th century and the earlier half of the
20th century, by the 1990s the majority of deforestation was caused by
industrial factors, including extractive industries, large-scale cattle
ranching, and extensive agriculture.
[29]
Environmental effects
Atmospheric
Deforestation is ongoing and is shaping
climate and
geography.
[30][31][32][33]
Deforestation is a contributor to
global warming,
[34][35] and is often cited as one of the major causes of the enhanced
greenhouse effect. Tropical deforestation is responsible for approximately 20% of world greenhouse gas emissions.
[36] According to the
Intergovernmental Panel on Climate Change deforestation, mainly in tropical areas, could account for up to one-third of total
anthropogenic carbon dioxide emissions.
[37] But recent calculations suggest that carbon dioxide emissions from deforestation and forest degradation (excluding
peatland emissions) contribute about 12% of total anthropogenic carbon dioxide emissions with a range from 6 to 17%.
[38]
Deforestation causes carbon dioxide to linger in the atmosphere. As
carbon dioxide accrues, it produces a layer in the atmosphere that traps
radiation from the sun. The radiation converts to heat which causes
global warming, which is better known as the greenhouse effect.
[39] Plants remove
carbon in the form of
carbon dioxide from the
atmosphere during the process of
photosynthesis,
but release some carbon dioxide back into the atmosphere during normal
respiration. Only when actively growing can a tree or forest remove
carbon, by storing it in plant tissues. Both the decay and burning of
wood releases much of this stored carbon back to the atmosphere.
Although an accumulation of wood is generally necessary for carbon
sequestration, in some forests the network of symbiotic fungi that
surround the trees' roots can store a significant amount of carbon,
storing it underground even if the tree which supplied it dies and
decays, or is harvested and burned.
[40]
Another way carbon can be sequestered by forests is for the wood to be
harvested and turned into long-lived products, with new young trees
replacing them.
[41] Deforestation may also cause carbon stores held in soil to be released.
Forests can be either sinks or sources depending upon environmental
circumstances. Mature forests alternate between being net sinks and net
sources of carbon dioxide (see
carbon dioxide sink and
carbon cycle).
In deforested areas, the land heats up faster and reaches a higher
temperature, leading to localized upward motions that enhance the
formation of clouds and ultimately produce more rainfall.
[42] However, according to the Geophysical Fluid Dynamics Laboratory, the
models used to investigate remote responses to tropical deforestation
showed a broad but mild temperature increase all through the tropical
atmosphere. The model predicted <0 .2="" 500="" 700="" absolutely="" air="" and="" are="" areas="" at="" be="" besides="" case="" changes="" class="reference" climate="" definite.="" errors="" for="" has="" however="" id="cite_ref-43" in="" may="" mb.="" mb="" model="" nbsp="" never="" no="" not="" other="" possible="" results="" showed="" shows="" significant="" since="" sup="" than="" the="" this="" though="" to="" tropics.="" tropics="" upper="" warming="">
[43]
Deforestation affects wind flows, water vapour flows and absorption of
solar energy thus clearly influencing local and global climate.
[44]
Reducing emissions from deforestation and forest degradation (REDD)
in developing countries has emerged as a new potential to complement
ongoing climate policies. The idea consists in providing financial
compensations for the reduction of greenhouse gas (GHG) emissions from
deforestation and forest degradation".
[45]
Rainforests are widely believed by laymen to contribute a significant amount of the world's oxygen,
[46] although it is now accepted by scientists that rainforests contribute little net
oxygen to the
atmosphere and deforestation has only a minor effect on atmospheric oxygen levels.
[47][48] However, the incineration and burning of forest plants to clear land releases large amounts of CO
2, which contributes to global warming.
[35] Scientists also state that tropical deforestation releases 1.5 billion tons of carbon each year into the atmosphere.
[49]
Hydrological
The
water cycle is also affected by deforestation. Trees extract
groundwater
through their roots and release it into the atmosphere. When part of a
forest is removed, the trees no longer transpire this water, resulting
in a much
drier climate.
Deforestation reduces the content of water in the soil and groundwater
as well as atmospheric moisture. The dry soil leads to lower water
intake for the trees to extract.
[50] Deforestation reduces soil cohesion, so that
erosion, flooding and
landslides ensue.
[51][52]
Shrinking
forest cover lessens the landscape's capacity to intercept, retain and
transpire
precipitation. Instead of trapping precipitation, which then percolates
to groundwater systems, deforested areas become sources of surface
water runoff, which moves much faster than subsurface flows. Forests
return most of the water that falls as precipitation to the atmosphere
by transpiration. In contrast, when an area is deforested, almost all
precipitation is lost as run-off.
[53] That quicker transport of surface water can translate into
flash flooding and more localized floods than would occur with the forest cover. Deforestation also contributes to decreased
evapotranspiration,
which lessens atmospheric moisture which in some cases affects
precipitation levels downwind from the deforested area, as water is not
recycled to downwind forests, but is lost in runoff and returns directly
to the oceans. According to one study, in deforested north and
northwest China, the average annual precipitation decreased by one third
between the 1950s and the 1980s.
[54]
Trees, and plants in general, affect the
water cycle significantly:
[55]
- their canopies intercept a proportion of precipitation, which is then evaporated back to the atmosphere (canopy interception);
- their litter, stems and trunks slow down surface runoff;
- their roots create macropores – large conduits – in the soil that increase infiltration of water;
- they contribute to terrestrial evaporation and reduce soil moisture via transpiration;
- their litter and other organic residue change soil properties that affect the capacity of soil to store water.
- their leaves control the humidity of the atmosphere by transpiring. 99% of the water absorbed by the roots moves up to the leaves and is transpired.[56]
As a result, the presence or absence of trees can change the quantity
of water on the surface, in the soil or groundwater, or in the
atmosphere. This in turn changes erosion rates and the availability of
water for either ecosystem functions or human services. Deforestation on
lowland plains moves cloud formation and rainfall to higher elevations.
[44]
The forest may have little impact on flooding in the case of large
rainfall events, which overwhelm the storage capacity of forest soil if
the soils are at or close to saturation.
Tropical rainforests produce about 30% of our planet's
fresh water.
[46]
Deforestation disrupts normal weather patterns creating hotter and
drier weather thus increasing drought, desertification, crop failures,
melting of the polar ice caps, coastal flooding and displacement of
major vegetation regimes.
[44]
Soil
Due to surface
plant litter, forests that are undisturbed have a minimal rate of
erosion.
The rate of erosion occurs from deforestation, because it decreases the
amount of litter cover, which provides protection from
surface runoff.
[57] The rate of erosion is around 2 metric tons per square kilometre.
[58]
This can be an advantage in excessively leached tropical rain forest
soils. Forestry operations themselves also increase erosion through the
development of (
forest)
roads and the use of mechanized equipment.
Deforestation in China's Loess Plateau many years ago has led to soil
erosion; this erosion has led to valleys opening up. The increase of
soil in the runoff causes the Yellow River to flood and makes it yellow
colored.
[58]
Greater erosion is not always a consequence of deforestation, as
observed in the southwestern regions of the US. In these areas, the loss
of grass due to the presence of trees and other shrubbery leads to more
erosion than when trees are removed.
[58]
Soils are reinforced by the presence of trees, which secure the soil
by binding their roots to soil bedrock. Due to deforestation, the
removal of trees causes sloped lands to be more susceptible to
landslides.[55]
Biodiversity
Deforestation on a human scale results in decline in
biodiversity,
[59] and on a natural global scale is known to cause the extinction of many species.
[8] The removal or destruction of areas of forest cover has resulted in a degraded environment with reduced
biodiversity.
[21] Forests support biodiversity, providing habitat for
wildlife;
[60] moreover, forests foster
medicinal conservation.
[61] With forest biotopes being irreplaceable source of new drugs (such as
taxol), deforestation can destroy
genetic variations (such as crop resistance) irretrievably.
[62]
Since the tropical rainforests are the most diverse
ecosystems on Earth
[63][64] and about 80% of the world's known
biodiversity could be found in tropical rainforests,
[65][66] removal or destruction of significant areas of forest cover has resulted in a
degraded[67] environment with reduced biodiversity. A study in
Rondônia,
Brazil, has shown that deforestation also removes the microbial
community which is involved in the recycling of nutrients, the
production of clean water and the removal of pollutants.
[69]
It has been estimated that we are losing 137 plant, animal and insect
species every single day due to rainforest deforestation, which equates
to 50,000 species a year.
[70] Others state that tropical rainforest deforestation is contributing to the ongoing
Holocene mass extinction.
[71][72]
The known extinction rates from deforestation rates are very low,
approximately 1 species per year from mammals and birds which
extrapolates to approximately 23,000 species per year for all species. Predictions have been made that more than 40% of the animal and
plant species in
Southeast Asia could be wiped out in the 21st century.
[73]
Such predictions were called into question by 1995 data that show that
within regions of Southeast Asia much of the original forest has been
converted to monospecific plantations, but that potentially endangered
species are few and tree flora remains widespread and stable.
[74]
Scientific understanding of the process of extinction is insufficient
to accurately make predictions about the impact of deforestation on
biodiversity.
[75]
Most predictions of forestry related biodiversity loss are based on
species-area models, with an underlying assumption that as the forest
declines species diversity will decline similarly.
[76]
However, many such models have been proven to be wrong and loss of
habitat does not necessarily lead to large scale loss of species.
[76]
Species-area models are known to overpredict the number of species
known to be threatened in areas where actual deforestation is ongoing,
and greatly overpredict the number of threatened species that are
widespread.
[74]
A recent study of the Brazilian Amazon predicts that despite a lack
of extinctions thus far, up to 90 percent of predicted extinctions will
finally occur in the next 40 years.
[77]
Economic impact
A satellite image showing deforestation for a palm oil plantation in Malaysia
Damage to forests and other aspects of nature could halve
living standards for the world's
poor and reduce global
GDP by about 7% by 2050, a report concluded at the
Convention on Biological Diversity (CBD) meeting in Bonn in 2008.
[78]
Historically, utilization of forest products, including timber and fuel
wood, has played a key role in human societies, comparable to the roles
of water and cultivable land. Today, developed countries continue to
utilize timber for building houses, and wood pulp for
paper. In developing countries almost three billion people rely on wood for heating and cooking.
[79]
The forest products industry is a large part of the economy in both
developed and developing countries. Short-term economic gains made by
conversion of forest to agriculture, or
over-exploitation of wood products, typically leads to loss of long-term income and long-term biological productivity.
West Africa,
Madagascar,
Southeast Asia
and many other regions have experienced lower revenue because of
declining timber harvests. Illegal logging causes billions of dollars of
losses to national economies annually.
[80]
The new procedures to get amounts of wood are causing more harm to
the economy and overpower the amount of money spent by people employed
in logging.
[81]
According to a study, "in most areas studied, the various ventures that
prompted deforestation rarely generated more than US$5 for every ton of
carbon they released and frequently returned far less than US$1". The
price on the European market for an offset tied to a one-ton reduction
in carbon is 23
euro (about US$35).
[82]
Rapidly growing economies also have an effect on deforestation. Most
pressure will come from the world's developing countries, which have the
fastest-growing populations and most rapid economic (industrial)
growth.
[83] In 1995, economic growth in developing countries reached nearly 6%, compared with the 2% growth rate for developed countries.”
[83]
As our human population grows, new homes, communities, and expansions
of cities will occur. Connecting all of the new expansions will be
roads, a very important part in our daily life. Rural roads promote
economic development but also facilitate deforestation.
[83] About 90% of the deforestation has occurred within 100 km of roads in most parts of the Amazon.
[84]
The
European Union is one of the largest importer of products made from illegal deforestation.
[85]
Forest transition theory
The forest transition and historical baselines.
[86]
The forest area change may follow a pattern suggested by the
forest transition (FT) theory,
[87]
whereby at early stages in its development a country is characterized
by high forest cover and low deforestation rates (HFLD countries).
[29]
Then deforestation rates accelerate (HFHD, high forest cover – high
deforestation rate), and forest cover is reduced (LFHD, low forest cover
– high deforestation rate), before the deforestation rate slows (LFLD,
low forest cover – low deforestation rate), after which forest cover
stabilizes and eventually starts recovering. FT is not a "law of
nature", and the pattern is influenced by national context (for example,
human population density, stage of development, structure of the
economy), global economic forces, and government policies. A country may
reach very low levels of forest cover before it stabilizes, or it might
through good policies be able to “bridge” the forest transition.
[88]
FT depicts a broad trend, and an extrapolation of historical rates
therefore tends to underestimate future BAU deforestation for counties
at the early stages in the transition (HFLD), while it tends to
overestimate BAU deforestation for countries at the later stages (LFHD
and LFLD).
Countries with high forest cover can be expected to be at early
stages of the FT. GDP per capita captures the stage in a country’s
economic development, which is linked to the pattern of natural resource
use, including forests. The choice of forest cover and GDP per capita
also fits well with the two key scenarios in the FT:
(i) a forest scarcity path, where forest scarcity triggers forces
(for example, higher prices of forest products) that lead to forest
cover stabilization; and
(ii) an economic development path, where new and better off-farm
employment opportunities associated with economic growth (= increasing
GDP per capita) reduce profitability of frontier agriculture and slows
deforestation.
[29]
Historical causes
Prehistory
The
Carboniferous Rainforest Collapse[8]
was an event that occurred 300 million years ago. Climate change
devastated tropical rainforests causing the extinction of many plant and
animal species. The change was abrupt, specifically, at this time
climate became cooler and drier, conditions that are not favourable to
the growth of rainforests and much of the biodiversity within them.
Rainforests were fragmented forming shrinking 'islands' further and
further apart. Populations such as the sub class
Lissamphibia were devastated, whereas
Reptilia
survived the collapse. The surviving organisms were better adapted to
the drier environment left behind and served as legacies in succession
after the collapse.
[7]
An array of Neolithic artifacts, including bracelets, axe heads, chisels, and polishing tools.
Rainforests once covered 14% of the earth's land surface; now they
cover a mere 6% and experts estimate that the last remaining rainforests
could be consumed in less than 40 years.
[89] Small scale deforestation was practiced by some societies for tens of thousands of years before the beginnings of civilization.
[90] The first evidence of deforestation appears in the
Mesolithic period.
[91] It was probably used to convert closed forests into more open ecosystems favourable to game animals.
[90] With the advent of agriculture, larger areas began to be deforested,
and fire became the prime tool to clear land for crops. In Europe there
is little solid evidence before 7000 BC. Mesolithic
foragers used fire to create openings for
red deer and
wild boar. In Great Britain, shade-tolerant species such as
oak and
ash are replaced in the
pollen record by
hazels, brambles, grasses and nettles. Removal of the forests led to decreased
transpiration, resulting in the formation of upland
peat bogs. Widespread decrease in
elm pollen
across Europe between 8400–8300 BC and 7200–7000 BC, starting in
southern Europe and gradually moving north to Great Britain, may
represent land clearing by fire at the onset of
Neolithic agriculture.
The
Neolithic period saw extensive deforestation for
farming land.
[92][93]
Stone axes were being made from about 3000 BC not just from flint, but
from a wide variety of hard rocks from across Britain and North America
as well. They include the noted
Langdale axe industry in the
English Lake District, quarries developed at
Penmaenmawr in
North Wales
and numerous other locations. Rough-outs were made locally near the
quarries, and some were polished locally to give a fine finish. This
step not only increased the
mechanical strength of the axe, but also made penetration of wood easier.
Flint was still used from sources such as
Grimes Graves but from many other mines across Europe.
Evidence of deforestation has been found in
Minoan Crete; for example the environs of the
Palace of Knossos were severely deforested in the
Bronze Age.
[94]
Pre-industrial history
Easter Island, deforested. According to
Jared Diamond:
"Among past societies faced with the prospect of ruinous deforestation,
Easter Island and Mangareva chiefs succumbed to their immediate
concerns, but Tokugawa shoguns, Inca emperors, New Guinea highlanders,
and 16th century German landowners adopted a long view and
reafforested."
[95]
Throughout prehistory, humans were hunter gatherers who hunted within forests. In most areas, such as the
Amazon, the tropics, Central America, and the Caribbean,
[96]
only after shortages of wood and other forest products occur are
policies implemented to ensure forest resources are used in a
sustainable manner.
Three regional studies of historic erosion and alluviation in
ancient Greece
found that, wherever adequate evidence exists, a major phase of erosion
follows the introduction of farming in the various regions of Greece by
about 500-1,000 years, ranging from the later Neolithic to the Early
Bronze Age.
[97]
The thousand years following the mid-first millennium BC saw serious,
intermittent pulses of soil erosion in numerous places. The historic
silting of ports along the southern coasts of
Asia Minor (
e.g. Clarus, and the examples of
Ephesus,
Priene and
Miletus, where harbors had to be abandoned because of the silt deposited by the Meander) and in coastal
Syria during the last centuries BC.
Easter Island has suffered from heavy
soil erosion in recent centuries, aggravated by agriculture and deforestation.
[98] Jared Diamond gives an extensive look into the collapse of the ancient Easter Islanders in his book
Collapse.
The disappearance of the island's trees seems to coincide with a
decline of its civilization around the 17th and 18th century. He
attributed the collapse to deforestation and over-exploitation of all
resources.
[99][100]
The famous silting up of the harbor for
Bruges, which moved port commerce to
Antwerp,
also followed a period of increased settlement growth (and apparently
of deforestation) in the upper river basins. In early medieval
Riez in upper
Provence,
alluvial silt from two small rivers raised the riverbeds and widened
the floodplain, which slowly buried the Roman settlement in alluvium and
gradually moved new construction to higher ground; concurrently the
headwater valleys above Riez were being opened to pasturage.
[101]
A typical
progress trap
was that cities were often built in a forested area, which would
provide wood for some industry (for example, construction, shipbuilding,
pottery). When deforestation occurs without proper replanting, however;
local wood supplies become difficult to obtain near enough to remain
competitive, leading to the city's abandonment, as happened repeatedly
in Ancient
Asia Minor. Because of fuel needs, mining and metallurgy often led to deforestation and city abandonment.
[102]
With most of the population remaining active in (or indirectly
dependent on) the agricultural sector, the main pressure in most areas
remained land clearing for crop and cattle farming. Enough wild green
was usually left standing (and partially used, for example, to collect
firewood, timber and fruits, or to graze pigs) for wildlife to remain
viable. The elite's (nobility and higher clergy) protection of their own
hunting privileges and game often protected significant woodland.
[88]
Major parts in the spread (and thus more durable growth) of the
population were played by monastical 'pioneering' (especially by the
Benedictine and
Commercial orders) and some
feudal
lords' recruiting farmers to settle (and become tax payers) by offering
relatively good legal and fiscal conditions. Even when speculators
sought to encourage towns, settlers needed an agricultural belt around
or sometimes within defensive walls. When populations were quickly
decreased by causes such as the
Black Death or devastating warfare (for example,
Genghis Khan's
Mongol hordes in eastern and central Europe,
Thirty Years' War in Germany), this could lead to settlements being abandoned. The land was reclaimed by nature, but the
secondary forests usually lacked the original
biodiversity.
From 1100 to 1500 AD, significant deforestation took place in
Western Europe as a result of the
expanding human population. The large-scale building of wooden sailing ships by European (coastal) naval owners since the 15th century for exploration,
colonisation,
slave trade–and other trade on the high seas consumed many forest resources.
Piracy
also contributed to the over harvesting of forests, as in Spain. This
led to a weakening of the domestic economy after Columbus' discovery of
America, as the economy became dependent on colonial activities
(plundering, mining, cattle, plantations, trade, etc.)
[103]
In
Changes In the Land (1983),
William Cronon analyzed and documented 17th-century English colonists' reports of increased seasonal flooding in
New England
during the period when new settlers initially cleared the forests for
agriculture. They believed flooding was linked to widespread forest
clearing upstream.
The massive use of
charcoal on an industrial scale in
Early Modern Europe
was a new type of consumption of western forests; even in Stuart
England, the relatively primitive production of charcoal has already
reached an impressive level. Stuart England was so widely deforested
that it depended on the
Baltic trade for ship timbers, and looked to the untapped forests of
New England to supply the need. Each of Nelson's
Royal Navy war ships at Trafalgar (1805) required 6,000 mature oaks for its construction. In France,
Colbert planted
oak
forests to supply the French navy in the future. When the oak
plantations matured in the mid-19th century, the masts were no longer
required because shipping had changed.
Norman F. Cantor's summary of the effects of late medieval deforestation applies equally well to Early Modern Europe:
[104]
Europeans had lived in the midst of vast forests throughout the
earlier medieval centuries. After 1250 they became so skilled at
deforestation that by 1500 they were running short of wood for heating
and cooking. They were faced with a nutritional decline because of the
elimination of the generous supply of wild game that had inhabited the
now-disappearing forests, which throughout medieval times had provided
the staple of their carnivorous high-protein diet. By 1500 Europe was on
the edge of a fuel and nutritional disaster [from] which it was saved
in the sixteenth century only by the burning of soft coal and the
cultivation of potatoes and maize.
Industrial era
In the 19th century, introduction of
steamboats in the United States was the cause of deforestation of banks of major rivers, such as the
Mississippi River,
with increased and more severe flooding one of the environmental
results. The steamboat crews cut wood every day from the riverbanks to
fuel the steam engines. Between
St. Louis and the confluence with the
Ohio River
to the south, the Mississippi became more wide and shallow, and changed
its channel laterally. Attempts to improve navigation by the use of
snag pullers often resulted in crews' clearing large trees 100 to 200 feet (61 m) back from the banks. Several French colonial towns of the
Illinois Country, such as
Kaskaskia,
Cahokia and St. Philippe,
Illinois, were flooded and abandoned in the late 19th century, with a loss to the cultural record of their
archeology.
[105]
The wholescale clearance of woodland to create agricultural land can be seen in many parts of the world, such as the
Central forest-grasslands transition and other areas of the
Great Plains of the
United States. Specific parallels are seen in the 20th-century deforestation occurring in many developing nations.
Rates of deforestation
Global deforestation
[106] sharply accelerated around 1852.
[107][108] It has been estimated that about half of the Earth's mature
tropical forests—between 7.5 million and 8 million km
2 (2.9 million to 3 million sq mi) of the original 15 million to 16 million km
2 (5.8 million to 6.2 million sq mi) that until 1947 covered the planet
[109]—have now been destroyed.
[9][110]
Some scientists have predicted that unless significant measures (such
as seeking out and protecting old growth forests that have not been
disturbed)
[109] are taken on a worldwide basis, by 2030 there will only be 10% remaining,
[107][110] with another 10%
in a degraded condition.
[107] 80% will have been lost, and with them hundreds of thousands of irreplaceable species.
[107] Some cartographers have attempted to illustrate the sheer scale of deforestation by country using a
cartogram.
[111]
Estimates vary widely as to the extent of tropical deforestation.
[112][113] Over a 50-year period, percentage of land cover by
tropical rainforests
has decreased by 50%. Where total land coverage by tropical rainforests
decreased from 14% to 6%. A large contribution to this loss can be
identified between 1960 and 1990, when 20% of all tropical rainforests
were destroyed. At this rate, extinction of such forests is projected to
occur by the mid 21st century.
[7]
A 2002 analysis of satellite imagery suggested that the rate of
deforestation in the humid tropics (approximately 5.8 million hectares
per year) was roughly 23% lower than the most commonly quoted rates.
[114] Conversely, a newer analysis of satellite images reveals that
deforestation of the Amazon rainforest is twice as fast as scientists previously estimated.
[115][116]
Some have argued that deforestation trends may follow a
Kuznets curve,
[117]
which if true would nonetheless fail to eliminate the risk of
irreversible loss of non-economic forest values (for example, the
extinction of species).
[118][119]
A 2005 report by the United Nations
Food and Agriculture Organization
(FAO) estimated that although the Earth's total forest area continued
to decrease at about 13 million hectares per year, the global rate of
deforestation has recently been slowing.
[120][121] The 2016 report by the FAO
[122]
reports from 2010 to 2015 there was a worldwide decrease in forest area
of 3.3 million ha per year. During this five-year period, the biggest
forest area loss occurred in the tropics, particularly in South America
and Africa. Per capita forest area decline was also greatest in the
tropics and subtropics but is occurring in every climatic domain (except
in the temperate) as populations increase.
Others claim that rainforests are being destroyed at an ever-quickening pace.
[123]
The London-based Rainforest Foundation notes that "the UN figure is
based on a definition of forest as being an area with as little as 10%
actual tree cover, which would therefore include areas that are actually
savannah-like ecosystems and badly damaged forests."
[124] Other critics of the FAO data point out that they do not distinguish between forest types,
[125] and that they are based largely on reporting from forestry departments of individual countries,
[126] which do not take into account unofficial activities like illegal logging.
[127]
Despite these uncertainties, there is agreement that destruction of
rainforests remains a significant environmental problem. Up to 90% of
West Africa's coastal rainforests have disappeared since 1900.
[128] In
South Asia, about 88% of the rainforests have been lost.
[129] Much of what remains of the world's rainforests is in the
Amazon basin, where the
Amazon Rainforest covers approximately 4 million square kilometres.
[130] The regions with the highest tropical deforestation rate between 2000 and 2005 were
Central America—which lost 1.3% of its forests each year—and tropical Asia.
[124] In
Central America,
two-thirds of lowland tropical forests have been turned into pasture
since 1950 and 40% of all the rainforests have been lost in the last 40
years.
[131] Brazil has lost 90–95% of its
Mata Atlântica forest.
[132] Paraguay
was losing its natural semi humid forests in the country’s western
regions at a rate of 15.000 hectares at a randomly studied 2-month
period in 2010,
[133] Paraguay’s parliament refused in 2009 to pass a law that would have stopped cutting of natural forests altogether.
[134]
Deforestation around Pakke Tiger Reserve, India
Madagascar has lost 90% of its eastern rainforests.
[135][136] As of 2007,
less than 50% of Haiti's forests remained.
[137] Mexico,
India, the
Philippines,
Indonesia,
Thailand,
Burma,
Malaysia,
Bangladesh, China,
Sri Lanka,
Laos,
Nigeria, the
Democratic Republic of the Congo,
Liberia,
Guinea,
Ghana and the
Ivory Coast, have lost large areas of their rainforest.
[138][139] Several countries, notably
Brazil, have declared their deforestation a national emergency.
[140][141] The
World Wildlife Fund's
ecoregion
project catalogues habitat types throughout the world, including
habitat loss such as deforestation, showing for example that even in the
rich forests of parts of
Canada such as the
Mid-Continental Canadian forests of the prairie provinces half of the forest cover has been lost or altered.
Regions
Rates of deforestation vary around the world.
In 2011
Conservation International listed the top 10 most endangered forests, characterized by having all lost 90% or more of their original
habitat, and each harboring at least 1500
endemic plant species (species found nowhere else in the world).
[142]
Top 10 Most Endangered Forests 2011
| Indo-Burma |
Asia-Pacific |
5% |
Tropical and subtropical moist broadleaf forests |
Rivers, floodplain wetlands, mangrove forests. Burma, Thailand, Laos, Vietnam, Cambodia, India.[143] |
| New Caledonia |
Asia-Pacific |
5% |
Tropical and subtropical moist broadleaf forests |
See note for region covered.[144] |
| Sundaland |
Asia-Pacific |
7% |
Tropical and subtropical moist broadleaf forests |
Western half of the Indo-Malayan archipelago including southern Borneo and Sumatra.[145] |
| Philippines |
Asia-Pacific |
7% |
Tropical and subtropical moist broadleaf forests |
Forests over the entire country including 7,100 islands.[146] |
| Atlantic Forest |
South America |
8% |
Tropical and subtropical moist broadleaf forests |
Forests along Brazil's Atlantic coast, extends to parts of Paraguay, Argentina and Uruguay.[147] |
| Mountains of Southwest China |
Asia-Pacific |
8% |
Temperate coniferous forest |
See note for region covered.[148] |
| California Floristic Province |
North America |
10% |
Tropical and subtropical dry broadleaf forests |
See note for region covered.[149] |
| Coastal Forests of Eastern Africa |
Africa |
10% |
Tropical and subtropical moist broadleaf forests |
Mozambique, Tanzania, Kenya, Somalia.[150] |
| Madagascar & Indian Ocean Islands |
Africa |
10% |
Tropical and subtropical moist broadleaf forests |
Madagascar, Mauritius, Reunion, Seychelles, Comoros.[151] |
| Eastern Afromontane |
Africa |
11% |
Tropical and subtropical moist broadleaf forests
Montane grasslands and shrublands |
Forests scattered along the eastern edge of Africa, from Saudi Arabia in the north to Zimbabwe in the south.[152] |
Control
Reducing emissions
Main international organizations including the United Nations and the
World Bank, have begun to develop programs aimed at curbing
deforestation. The blanket term
Reducing Emissions from Deforestation and Forest Degradation
(REDD) describes these sorts of programs, which use direct monetary or
other incentives to encourage developing countries to limit and/or roll
back deforestation. Funding has been an issue, but at the
UN Framework Convention on Climate Change
(UNFCCC) Conference of the Parties-15 (COP-15) in Copenhagen in
December 2009, an accord was reached with a collective commitment by
developed countries for new and additional resources, including forestry
and investments through international institutions, that will approach
USD 30 billion for the period 2010–2012.
[153]
Significant work is underway on tools for use in monitoring developing
country adherence to their agreed REDD targets. These tools, which rely
on remote forest monitoring using satellite imagery and other data
sources, include the
Center for Global Development's FORMA (Forest Monitoring for Action) initiative
[154] and the
Group on Earth Observations' Forest Carbon Tracking Portal.
[155] Methodological guidance for forest monitoring was also emphasized at COP-15.
[156] The environmental organization
Avoided Deforestation Partners leads the campaign for development of REDD through funding from the U.S. government.
[157] In 2014, the
Food and Agriculture Organization of the United Nations
and partners launched Open Foris – a set of open-source software tools
that assist countries in gathering, producing and disseminating
information on the state of forest resources.
[158]
The tools support the inventory lifecycle, from needs assessment,
design, planning, field data collection and management, estimation
analysis, and dissemination. Remote sensing image processing tools are
included, as well as tools for international reporting for
Reducing emissions from deforestation and forest degradation (REDD) and MRV (Measurement, Reporting and Verification)
[159] and FAO's
Global Forest Resource Assessments.
In evaluating implications of overall emissions reductions, countries
of greatest concern are those categorized as High Forest Cover with
High Rates of Deforestation (HFHD) and Low Forest Cover with High Rates
of Deforestation (LFHD). Afghanistan, Benin, Botswana, Burma, Burundi,
Cameroon, Chad, Ecuador, El Salvador, Ethiopia, Ghana, Guatemala,
Guinea,
Haiti,
Honduras, Indonesia, Liberia, Malawi, Mali, Mauritania, Mongolia,
Namibia, Nepal, Nicaragua, Niger, Nigeria, Pakistan, Paraguay,
Philippines, Senegal, Sierra Leone, Sri Lanka, Sudan, Togo, Uganda,
United Republic of Tanzania, Zimbabwe are listed as having Low Forest
Cover with High Rates of Deforestation (LFHD). Brazil, Cambodia,
Democratic Peoples Republic of Korea, Equatorial Guinea, Malaysia,
Solomon Islands, Timor-Leste, Venezuela, Zambia are listed as High
Forest Cover with High Rates of Deforestation (HFHD).
[160]
Payments for conserving forests
In
Bolivia, deforestation in upper river basins has caused environmental
problems, including soil erosion and declining water quality. An
innovative project to try and remedy this situation involves landholders
in upstream areas being paid by downstream water users to conserve
forests. The landholders receive US$20 to conserve the trees, avoid
polluting livestock practices, and enhance the biodiversity and forest
carbon on their land. They also receive US$30, which purchases a
beehive, to compensate for conservation for two hectares of
water-sustaining forest for five years. Honey revenue per hectare of
forest is US$5 per year, so within five years, the landholder has sold
US$50 of honey.
[161] The project is being conducted by
Fundación Natura Bolivia and Rare Conservation, with support from the
Climate & Development Knowledge Network.
Land rights
Transferring
land rights to indigenous inhabitants is argued to efficiently conserve forests.
Transferring rights over land from public domain to its indigenous
inhabitants is argued to be a cost effective strategy to conserve
forests.
[162] This includes the protection of such rights entitled in existing laws, such as India’s
Forest Rights Act.
[162] The transferring of such rights in
China, perhaps the largest
land reform in modern times, has been argued to have increased forest cover.
[163] In
Brazil, forested areas given tenure to indigenous groups have even lower rates of clearing than
national parks.
[163]
Farming
New methods are being developed to farm more intensively, such as high-yield
hybrid crops,
greenhouse,
autonomous building gardens, and
hydroponics. These methods are often dependent on chemical inputs to maintain necessary yields. In cyclic
agriculture,
cattle are grazed on farm land that is resting and rejuvenating. Cyclic
agriculture actually increases the fertility of the soil. Intensive
farming can also decrease soil nutrients by consuming at an accelerated
rate the trace minerals needed for crop growth.
[7] The most promising approach, however, is the concept of
food forests in
permaculture,
which consists of agroforestal systems carefully designed to mimic
natural forests, with an emphasis on plant and animal species of
interest for food, timber and other uses. These systems have low
dependence on
fossil fuels and
agro-chemicals, are highly self-maintaining, highly productive, and with strong positive impact on soil and water quality, and
biodiversity.
Monitoring deforestation
There
are multiple methods that are appropriate and reliable for reducing and
monitoring deforestation. One method is the “visual interpretation of
aerial photos or satellite imagery that is labor-intensive but does not
require high-level training in computer image processing or extensive
computational resources”.
[84]
Another method includes hot-spot analysis (that is, locations of rapid
change) using expert opinion or coarse resolution satellite data to
identify locations for detailed digital analysis with high resolution
satellite images.
[84]
Deforestation is typically assessed by quantifying the amount of area
deforested, measured at the present time. From an environmental point of
view, quantifying the damage and its possible consequences is a more
important task, while conservation efforts are more focused on forested
land protection and development of land-use alternatives to avoid
continued deforestation.
[84]
Deforestation rate and total area deforested, have been widely used for
monitoring deforestation in many regions, including the Brazilian
Amazon deforestation monitoring by INPE.
[49] A global satellite view is available.
[164][165]
Forest management
Efforts
to stop or slow deforestation have been attempted for many centuries
because it has long been known that deforestation can cause
environmental damage sufficient in some cases to cause societies to
collapse. In
Tonga,
paramount rulers developed policies designed to prevent conflicts
between short-term gains from converting forest to farmland and
long-term problems forest loss would cause,
[166] while during the 17th and 18th centuries in
Tokugawa, Japan,
[167]
the shoguns developed a highly sophisticated system of long-term
planning to stop and even reverse deforestation of the preceding
centuries through substituting timber by other products and more
efficient use of land that had been farmed for many centuries. In
16th-century Germany, landowners also developed
silviculture to deal with the problem of deforestation. However, these policies tend to be limited to environments with
good rainfall,
no dry season and
very young soils (through
volcanism or
glaciation).
This is because on older and less fertile soils trees grow too slowly
for silviculture to be economic, whilst in areas with a strong dry
season there is always a risk of forest fires destroying a tree crop
before it matures.
In the areas where "
slash-and-burn" is practiced, switching to "
slash-and-char" would prevent the rapid deforestation and subsequent degradation of soils. The
biochar thus created, given back to the soil, is not only a durable
carbon sequestration method, but it also is an extremely beneficial
amendment to the soil. Mixed with
biomass it brings the creation of
terra preta, one of the richest soils on the planet and the only one known to regenerate itself.
Sustainable practices
Bamboo is advocated as a more sustainable alternative for cutting down wood for fuel.
[168]
Certification, as provided by global certification systems such as
Programme for the Endorsement of Forest Certification and
Forest Stewardship Council,
contributes to tackling deforestation by creating market demand for
timber from sustainably managed forests. According to the United Nations
Food and Agriculture Organization (FAO), "A major condition for the
adoption of sustainable forest management is a demand for products that
are produced sustainably and consumer willingness to pay for the higher
costs entailed. Certification represents a shift from regulatory
approaches to market incentives to promote sustainable forest
management. By promoting the positive attributes of forest products from
sustainably managed forests, certification focuses on the demand side
of environmental conservation."
[169] Rainforest Rescue argues that the standards of organizations like FSC are too closely connected to
timber industry
interests and therefore do not guarantee environmentally and socially
responsible forest management. In reality, monitoring systems are
inadequate and various cases of fraud have been documented worldwide.
[170]
Some nations have taken steps to help increase the number of trees on
Earth. In 1981, China created National Tree Planting Day Forest and
forest coverage had now reached 16.55% of China's land mass, as against
only 12% two decades ago.
[171]
Using fuel from
bamboo
rather than wood results in cleaner burning, and since bamboo matures
much faster than wood, deforestation is reduced as supply can be
replenished faster.
[168]
Reforestation
In many parts of the world, especially in East Asian countries, reforestation and
afforestation are increasing the area of forested lands.
[172] The amount of woodland has increased in 22 of the world's 50 most forested nations. Asia as a whole gained 1 million
hectares
of forest between 2000 and 2005. Tropical forest in El Salvador
expanded more than 20% between 1992 and 2001. Based on these trends, one
study projects that global forest will increase by 10%—an area the size
of India—by 2050.
[173]
In the
People's Republic of China,
where large scale destruction of forests has occurred, the government
has in the past required that every able-bodied citizen between the ages
of 11 and 60 plant three to five trees per year or do the equivalent
amount of work in other forest services. The government claims that at
least 1
billion
trees have been planted in China every year since 1982. This is no
longer required today, but 12 March of every year in China is the
Planting Holiday. Also, it has introduced the
Green Wall of China
project, which aims to halt the expansion of the Gobi desert through
the planting of trees. However, due to the large percentage of trees
dying off after planting (up to 75%), the project is not very
successful.
[citation needed] There has been a 47-million-hectare increase in forest area in China since the 1970s.
[173]
The total number of trees amounted to be about 35 billion and 4.55% of
China's land mass increased in forest coverage. The forest coverage was
12% two decades ago and now is 16.55%.
[171]
An ambitious proposal for China is the Aerially Delivered
Re-forestation and Erosion Control System and the proposed Sahara Forest
Project coupled with the
Seawater Greenhouse.
In Western countries, increasing consumer demand for wood products
that have been produced and harvested in a sustainable manner is causing
forest landowners and
forest industries to become increasingly accountable for their forest management and timber harvesting practices.
The
Arbor Day Foundation's
Rain Forest Rescue program is a charity that helps to prevent
deforestation. The charity uses donated money to buy up and preserve
rainforest land before the
lumber
companies can buy it. The Arbor Day Foundation then protects the land
from deforestation. This also locks in the way of life of the primitive
tribes living on the forest land. Organizations such as
Community Forestry International,
Cool Earth,
The Nature Conservancy,
World Wide Fund for Nature,
Conservation International,
African Conservation Foundation and
Greenpeace also focus on preserving forest habitats. Greenpeace in particular has also mapped out the forests that are still intact
[174] and published this information on the internet.
[175] World Resources Institute in turn has made a simpler thematic map
[176] showing the amount of forests present just before the age of man (8000 years ago) and the current (reduced) levels of forest.
[177] These maps mark the amount of afforestation required to repair the damage caused by people.
Forest plantations
In
order to acquire the world’s demand for wood, it is suggested that high
yielding forest plantations are suitable according to forest writers
Botkins and
Sedjo.
Plantations that yield 10 cubic meters per hectare a year would supply
enough wood for trading of 5% of the world’s existing forestland. By
contrast, natural forests produce about 1–2 cubic meters per hectare;
therefore, 5–10 times more forestland would be required to meet demand.
Forester Chad Oliver has suggested a forest mosaic with high-yield
forest lands interspersed with conservation land.
[178]
Globally, planted forests increased from 4.1% to 7.0% of the total forest area between 1990 and 2015.
[179] Plantation forests made up 280 million ha in 2015, an increase of about 40 million ha in the last ten years.
[180]
Globally, planted forests consist of about 18% exotic or introduced
species while the rest are species native to the country where they are
planted. In South America, Oceania, and East and Southern Africa,
planted forests are dominated by introduced species: 88%, 75% and 65%,
respectively. In North America, West and Central Asia, and Europe the
proportions of introduced species in plantations are much lower at 1%,
3% and 8% of the total area planted, respectively.
[179]
In the country of Senegal, on the western coast of Africa, a movement
headed by youths has helped to plant over 6 million mangrove trees. The
trees will protect local villages from storm damages and will provide a
habitat for local wildlife. The project started in 2008, and already
the Senegalese government has been asked to establish rules and
regulations that would protect the new mangrove forests.
[181]
Military context
American
Sherman tanks knocked out by Japanese artillery on Okinawa.
While demands for agricultural and urban use for the human population
cause the preponderance of deforestation, military causes can also
intrude. One example of deliberate deforestation played out in the U.S.
zone of occupation in Germany after
World War II ended in 1945. Before the onset of the
Cold War,
defeated Germany was still considered a potential future threat rather
than a potential future ally. To address this threat, the victorious
Allies made attempts to
lower German industrial potential, of which forests were deemed
[by whom?]
an element. Sources in the U.S. government admitted that the purpose of
this was that the "ultimate destruction of the war potential of German
forests". As a consequence of the practice of clear-felling,
deforestation resulted which could "be replaced only by long forestry
development over perhaps a century".
[182]
Operations in
war can also cause deforestation. For example, in the 1945
Battle of Okinawa,
bombardment and other
combat operations reduced a lush tropical landscape into "a vast field of mud, lead, decay and maggots".
[183]
Deforestation can also result from the intentional
tactics of
military forces. Clearing forest became an element in the Russian Empire's successful
conquest of the Caucasus in the mid-19th century.
[184] The British (during the
Malayan Emergency) and the United States (in the
Korean War[citation needed] and in the
Vietnam War) used
defoliants (like
Agent Orange or others).
[185][186][187][need quotation to verify]
Public health context
Deforestation eliminates a great number of species of plants and animals which also often results in an increase in disease.
[188]
Loss of native species allows new species to come to dominance. Often
the destruction of predatory species can result in an increase in rodent
populations which can carry
plague.
Additionally, erosion can produce pools of stagnant water that are
perfect breeding grounds for mosquitos, well known vectors of
malaria,
yellow fever,
nipah virus, and more.
[189]
Deforestation can also create a path for non-native species to flourish
such as certain types of snails, which have been correlated with an
increase in
schistosomiasis cases.
[188][190]
Deforestation is occurring all over the world and has been coupled with an increase in the occurrence of disease outbreaks. In
Malaysia,
thousands of acres of forest have been cleared for pig farms. This has
resulted in an increase in the zoonosis the Nipah virus.
[191] In
Kenya, deforestation has led to an increase in malaria cases which is now the leading cause of morbidity and mortality the country.
[192][193] A 2017 study in the
American Economic Review found that deforestation substantially increased the incidence of malaria in Nigeria.
[194]
Another pathway through which deforestation affects disease is the
relocation and dispersion of disease-carrying hosts. This disease
emergence pathway can be called "
range expansion", whereby the host’s range (and thereby the range of pathogens) expands to new geographic areas.
[195]
Through deforestation, hosts and reservoir species are forced into
neighboring habitats. Accompanying the reservoir species are pathogens
that have the ability to find new hosts in previously unexposed regions.
As these pathogens and species come into closer contact with humans,
they are infected both directly and indirectly.
A catastrophic example of range expansion is the 1998 outbreak of Nipah virus in Malaysia.
[196] For a number of years, deforestation, drought, and subsequent fires led to a dramatic geographic shift and density of
fruit bats, a reservoir for Nipah virus.
[197]
Deforestation reduced the available fruiting trees in the bats’
habitat, and they encroached on surrounding orchards which also happened
to be the location of a large number of pigsties. The bats, through
proximity spread the Nipah to pigs. While the virus infected the pigs,
mortality was much lower than among humans, making the pigs a virulent
host leading to the transmission of the virus to humans. This resulted
in 265 reported cases of
encephalitis,
of which 105 resulted in death. This example provides an important
lesson for the impact deforestation can have on human health.
Another example of range expansion due to deforestation and other
anthropogenic habitat impacts includes the
Capybara rodent in
Paraguay.
[198] This rodent is the host of a number of
zoonotic
diseases and, while there has not yet been a human-borne outbreak due
to the movement of this rodent into new regions, it offers an example of
how habitat destruction through deforestation and subsequent movements
of species is occurring regularly.
A now well-developed theory is that the spread of
HIV
it is at least partially due deforestation. Rising populations created a
food demand and with deforestation opening up new areas of the forest
the hunters harvested a great deal of primate bushmeat, which is
believed to be the origin of HIV.
[188]
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