Saturday, March 13, 2010

Mineral Depletion, Deforestation, Coral Bleaching, Mangrove Ecosystem

Minerals Depletion

L. David Roper
 http://arts.bev.net/RoperLDavid/
12 January, 2010

In the mid-1970s I taught an energy course at VPI&SU. I became interested in how minerals depletion was estimated and decided that I could do it better than had been done.

I used the least-squares-fit program of my colleague, Dr. Richard A. Arndt, to fit production-rate data for most minerals mined in the United States and the world.

Three books were published of that work:

Recently I have redone some of that work using the Solver part of Microsoft Excel to do the fits.

See Depletion Theory for a summary of the mathematics used in this research.

Verhulst Function for modeling minerals depletion.

Most recent minerals-depletion work:

Minerals Depletion proportional to available fossil-fuels energy

Mining the Oceans

Triple Threats for the Human Future



Deforestation


Jungle burned for agriculture in southern Mexico.
deforestation in the Paraguay Chaco
Deforestation and increased road-building in the Amazon Rainforest are a significant concern because of increased human encroachment upon wild areas, increased resource extraction and further threats to biodiversity.

Deforestation is the clearance of naturally occurring forests by logging and burning.

Deforestation occurs for many reasons: trees or derived charcoal are used as, or sold, for fuel or as a commodity, while cleared land is used as pasture for livestock, plantations of commodities, and settlements. The removal of trees without sufficient reforestation has resulted in damage to habitat, biodiversity loss and aridity. It has adverse impacts on biosequestration of atmospheric carbon dioxide. Deforested regions typically incur significant adverse soil erosion and frequently degrade into wasteland.

Disregard or ignorance of intrinsic value, lack of ascribed value, lax forest management and deficient environmental law are some of the factors that allow deforestation to occur on a large scale. In many countries, deforestation is an ongoing issue that is causing extinction, changes to climatic conditions, desertification, and displacement of indigenous people.

Among countries with a per capita GDP of at least US$4,600, net deforestation rates have ceased to increase.[1][2]

Contents

Causes of deforestation

There are many root causes of contemporary deforestation, including corruption of government institutions,[3][4] the inequitable distribution of wealth and power,[5] population growth[6] and overpopulation,[7][8] and urbanization.[9] Globalization is often viewed as another root cause of deforestation,[10][11] though there are cases in which the impacts of globalization (new flows of labor, capital, commodities, and ideas) have promoted localized forest recovery.[12]

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."[6]

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% of deforestation; logging is responsible for 14% of deforestation and fuel wood removals make up 5% of deforestation.[13]

The degradation of forest ecosystems has also been traced to economic incentives that make forest conversion appear more profitable than forest conservation.[14] 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.[14] 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 greatly from this deforestation, and that it is hypocritical to deny developing countries the same opportunities: that the poor shouldn't have to bear the cost of preservation when the rich created the problem.[15]

Experts do not agree on whether industrial logging is an important contributor to global deforestation.[16][17] Similarly, there is no consensus on whether poverty is important in deforestation. 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.[16] Claims that population growth drives deforestation have been disputed;[16] one study found that population increases due to high fertility rates were a primary driver of tropical deforestation in only 8% of cases.[18]

Some commentators have noted a shift in the drivers of deforestation over the past 30 years.[19] 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 etc during 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.[20]

Environmental problems

Atmospheric

Deforestation is ongoing and is shaping climate and geography.[21][22][23][24]

Deforestation is a contributor to global warming,[25][26] 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.[27] 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.[28] 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%.[29] Trees and other plants remove carbon (in the form of carbon dioxide) from the atmosphere during the process of photosynthesis and release oxygen back into the atmosphere during normal respiration. Only when actively growing can a tree or forest remove carbon over an annual or longer timeframe. Both the decay and burning of wood releases much of this stored carbon back to the atmosphere. In order for forests to take up carbon, the wood must be harvested and turned into long-lived products and trees must be re-planted.[30] Deforestation may cause carbon stores held in soil to be released. Forests are stores of carbon and 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).

Reducing emissions from the tropical deforestation and forest degradation (REDD) in developing countries has emerged as 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".[31]

Rainforests are widely believed by laymen to contribute a significant amount of world's oxygen,[32] although it is now accepted by scientists that rainforests contribute little net oxygen to the atmosphere and deforestation will have no effect on atmospheric oxygen levels.[33][34] However, the incineration and burning of forest plants to clear land releases large amounts of CO2, which contributes to global warming.[26]

Forests are also able to extract carbon dioxide and pollutants from the air, thus contributing to biosphere stability.[citation needed]

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 evaporate away this water, resulting in a much drier climate. Deforestation reduces the content of water in the soil and groundwater as well as atmospheric moisture.[35] Deforestation reduces soil cohesion, so that erosion, flooding and landslides ensue.[36][37] Forests enhance the recharge of aquifers in some locales, however, forests are a major source of aquifer depletion on most locales.[38]

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. 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 down wind 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 preliminary study, in deforested north and northwest China, the average annual precipitation decreased by one third between the 1950s and the 1980s.[citation needed]

Trees, and plants in general, affect the water cycle significantly:

  • 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.[39]

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.

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.[32]

Soil

Deforestation for the use of clay in the Brazilian city of Rio de Janeiro. The hill depicted is Morro da Covanca, in Jacarepaguá

Undisturbed forest has very low rates of soil loss, approximately 2 metric tons per square kilometer (6 short tons per square mile).[citation needed] Deforestation generally increases rates of soil erosion, by increasing the amount of runoff and reducing the protection of the soil from tree litter. This can be an advantage in excessively leached tropical rain forest soils. Forestry operations themselves also increase erosion through the development of roads and the use of mechanized equipment.

China's Loess Plateau was cleared of forest millennia ago. Since then it has been eroding, creating dramatic incised valleys, and providing the sediment that gives the Yellow River its yellow color and that causes the flooding of the river in the lower reaches (hence the river's nickname 'China's sorrow').

Removal of trees does not always increase erosion rates. In certain regions of southwest US, shrubs and trees have been encroaching on grassland. The trees themselves enhance the loss of grass between tree canopies. The bare intercanopy areas become highly erodible. The US Forest Service, in Bandelier National Monument for example, is studying how to restore the former ecosystem, and reduce erosion, by removing the trees.

Tree roots bind soil together, and if the soil is sufficiently shallow they act to keep the soil in place by also binding with underlying bedrock. Tree removal on steep slopes with shallow soil thus increases the risk of landslides, which can threaten people living nearby. However most deforestation only affects the trunks of trees, allowing for the roots to stay rooted, negating the landslide.

Ecological

Deforestation results in declines in biodiversity.[40] The removal or destruction of areas of forest cover has resulted in a degraded environment with reduced biodiversity.[41] Forests support biodiversity, providing habitat for wildlife;[42] moreover, forests foster medicinal conservation.[43] With forest biotopes being irreplaceable source of new drugs (such as taxol), deforestation can destroy genetic variations (such as crop resistance) irretrievably.[44]

Since the tropical rainforests are the most diverse ecosystems on Earth[45][46] and about 80% of the world's known biodiversity could be found in tropical rainforests,[47][48] removal or destruction of significant areas of forest cover has resulted in a degraded[49] environment with reduced biodiversity.[50]

Scientific understanding of the process of extinction is insufficient to accurately make predictions about the impact of deforestation on biodiversity.[51] Most predictions of forestry related biodiversity loss are based on species-area models, with an underlying assumption that as forest are declines species diversity will decline similarly.[52] However, many such models have been proven to be wrong and loss of habitat does not necessarily lead to large scale loss of species.[52] 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.[53]

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.[54] Others state that tropical rainforest deforestation is contributing to the ongoing Holocene mass extinction.[55][56] 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.[57] 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.[53]

Economic impact

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 major report concluded at the Convention on Biological Diversity (CBD) meeting in Bonn.[58] Historically utilization of forest products, including timber and fuel wood, have 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.[59]

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 (hence reduction in nature's services). 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.[60]

The new procedures to get amounts of wood are causing more harm to the economy and overpowers the amount of money spent by people employed in logging.[61] 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).[62]

Historical causes

Further information: Timeline of environmental events

Prehistory

An array of Neolithic artifacts, including bracelets, axe heads, chisels, and polishing tools.

Small scale deforestation was practiced by some societies for tens of thousands of years before the beginnings of civilization.[63] The first evidence of deforestation appears in the Mesolithic period.[64] It was probably used to convert closed forests into more open ecosystems favourable to game animals.[63] 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.[65][66] 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.[67]

Pre-industrial history

Throughout most of history, humans were hunter gatherers who hunted within forests. In most areas, such as the Amazon, the tropics, Central America, and the Caribbean,[68] only after shortages of wood and other forest products occur are policies implemented to ensure forest resources are used in a sustainable manner.

In ancient Greece, Tjeered van Andel and co-writers[69] summarized three regional studies of historic erosion and alluviation and found that, wherever adequate evidence exists, a major phase of erosion follows, by about 500-1,000 years the introduction of farming in the various regions of Greece, ranging from the later Neolithic to the Early Bronze Age. The thousand years following the mid-first millennium BCE 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.[70] 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.[71][72]

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.[citation needed]

Loss of old growth forest in the United States; 1620, 1850, and 1920 maps:
From William B. Greeley's, The Relation of Geography to Timber Supply, Economic Geography, 1925, vol. 1, p. 1-11. Source of "Today" map: compiled by George Draffan from roadless area map in The Big Outside: A Descriptive Inventory of the Big Wilderness Areas of the United States, by Dave Foreman and Howie Wolke (Harmony Books, 1992). These maps represent only virgin forest lost. Some regrowth has occurred but not to the age, size or extent of 1620 due to population increases and food cultivation.

A typical progress trap was that cities were often built in a forested area, which would provide wood for some industry (e.g. 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.[citation needed]

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, e.g. 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 woodlands.[citation needed]

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 (e.g. 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.)[citation needed]

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-nineteenth 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:[73]

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 snagpullers often resulted in crews' clearing large trees 100 to 200 feet 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.[74]

Specific parallels are seen in the twentieth-century deforestation occurring in many developing nations.

Rates of deforestation

Orbital photograph of human deforestation in progress in the Tierras Bajas project in eastern Bolivia

Global deforestation sharply accelerated around 1852.[75][76] It has been estimated that about half of the Earth's mature tropical forests—between 7.5 million and 8 million km2 (2.9 million to 3 million sq mi) of the original 15 million to 16 million km2 (5.8 million to 6.2 million sq mi) that until 1947 covered the planet[77]—have now been cleared.[78][79] Some scientists have predicted that unless significant measures (such as seeking out and protecting old growth forests that have not been disturbed)[77] are taken on a worldwide basis, by 2030 there will only be ten percent remaining,[75][78] with another ten percent in a degraded condition.[75] 80% will have been lost, and with them hundreds of thousands of irreplaceable species.[75]

The difficulties of estimating deforestation rates are nowhere more apparent than in the widely varying estimates of rates of rainforest deforestation. Some environmental groups argue that one fifth of the world's tropical rainforest was destroyed between 1960 and 1990, that rainforests 50 years ago covered 14% of the world's land surface and have been reduced to 6%,[54] and that all tropical forests will be gone by 2090.[54] Meanwhile, Alan Grainger of Leeds University argues that there is no credible evidence of any long-term decline in rainforest area.[80] Bjørn Lomborg, author of The Skeptical Environmentalist, claims that global forest cover has remained approximately stable since the middle of the twentieth century.[81][82] Along similar lines, some have claimed that for every acre of rain forest cut down each year, more than 50 acres (20 ha) of new forest are growing in the tropics.[83]

These divergent viewpoints are the result of the uncertainties in the extent of tropical deforestation. For tropical countries, deforestation estimates are very uncertain and could be in error by as much as +/- 50%,[84] while 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.[85] Conversely, a new analysis of satellite images reveals that deforestation of the Amazon rainforest is twice as fast as scientists previously estimated.[86][87]

Some have argued that deforestation trends may follow a Kuznets curve,[88] which if true would nonetheless fail to eliminate the risk of irreversible loss of non-economic forest values (e.g., the extinction of species).[89][90]

A 2005 report by the United Nations Food and Agriculture Organization (FAO) estimates that although the Earth's total forest area continues to decrease at about 13 million hectares per year, the global rate of deforestation has recently been slowing.[91][92] Still others claim that rainforests are being destroyed at an ever-quickening pace.[93] 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."[94] Other critics of the FAO data point out that they do not distinguish between forest types,[95] and that they are based largely on reporting from forestry departments of individual countries,[96] which do not take into account unofficial activities like illegal logging.[97]

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.[98] In South Asia, about 88% of the rainforests have been lost.[99] Much of what remains of the world's rainforests is in the Amazon basin, where the Amazon Rainforest covers approximately 4 million square kilometres.[100] 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.[94] 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.[101] Brazil has lost 90-95% of its Mata Atlântica forest.[102] Madagascar has lost 90% of its eastern rainforests.[103][104] As of 2007, less than 1% of Haiti's forests remained.[105] Mexico, India, the Philippines, Indonesia, Thailand, Myanmar, Malaysia, Bangladesh, China, Sri Lanka, Laos, Nigeria, the Democratic Republic of the Congo, Liberia, Guinea, Ghana and the Côte d'Ivoire, have lost large areas of their rainforest.[106][107] Several countries, notably Brazil, have declared their deforestation a national emergency.[108][109]

Deforestation by region

Main article: Deforestation by region

Rates of deforestation vary around the world. Southeast Asia and parts of South America are among the regions of highest concern to environmentalists.

Controlling deforestation

Reducing Emissions from Deforestation and Forest Degradation (REDD)

Main article: Reducing emissions from deforestation and forest degradation

Major 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.[110] 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 [2] and the Group on Earth Observations' Forest Carbon Tracking Portal [3]. Methodological guidance for forest monitoring was also emphasized at COP-15 [111]

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.[citation needed]

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,[112] while during the seventeenth and eighteenth centuries in Tokugawa, Japan,[113] 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 sixteenth 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.

Certification of sustainable forest management practices

Certification, as provided by global certification systems such as PEFC and FSC, 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."[114]

Reforestation

Main article: Reforestation

In many parts of the world, especially in East Asian countries, reforestation and afforestation are increasing the area of forested lands.[115] 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.[116]

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 March 12 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.[116] 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%.[117]

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 [4] and published this information on the internet.[118] HowStuffWorks in turn has made a simpler thematic map[119] showing the amount of forests present just before the age of man (8000 years ago) and the current (reduced) levels of forest.[120] These maps mark the amount of afforestation required to repair the damage caused by man.

Forest plantations

To meet the world's demand for wood, it has been suggested by forestry writers Botkins and Sedjo that high-yielding forest plantations are suitable. It has been calculated that plantations yielding 10 cubic meters per hectare annually could supply all the timber required for international trade on 5% of the world's existing forestland. By contrast, natural forests produce about 1-2 cubic meters per hectare; therefore, 5 to 10 times more forestland would be required to meet demand. Forester Chad Oliver has suggested a forest mosaic with high-yield forest lands interpersed with conservation land.[121]

One analysis of FAO data suggests that afforestation and reforestation projects "could reverse the global decline in woodlands within 30 years."[122]

Reforestation through tree planting could take advantage of changing precipitation patterns due to climate change. This would be done by studying where precipitation is projected to increase (see the "2050 Precipitation" thematic map created by Globalis) and setting up reforestation projects in these locations. Areas such as Niger, Sierra Leone and Liberia are especially important candidates because they also suffer from an expanding desert (the Sahara) and decreasing biodiversity (while being important biodiversity hotspots).

Military context

American Sherman tanks knocked out by Japanese artillery on Okinawa.

While the preponderance of deforestation is due to demands for agricultural and urban use for the human population, there are some examples of military causes. One example of deliberate deforestation is that which took place in the U.S. zone of occupation in Germany after World War II. Before the onset of the Cold War defeated Germany was still considered a potential future threat rather than potential future ally. To address this threat, attempts were made to lower German industrial potential, of which forests were deemed an element. Sources in the U.S. government admitted that the purpose of this was 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."[123]

War can also be a cause of deforestation, either deliberately such as through the use of Agent Orange[124] during the Vietnam War where, together with bombs and bulldozers, it contributed to the destruction of 44% of the forest cover,[125] or inadvertently such as in the 1945 Battle of Okinawa where bombardment and other combat operations reduced the lush tropical landscape into "a vast field of mud, lead, decay and maggots".[126]

See also: Environmental issues with war

See also

Environment portal
Ecology portal
Earth sciences portal
Biology portal
Sustainable development portal

References

Notes
  1. ^ Returning forests analyzed with the forest identity, 2006, by Pekka E. Kauppi (Department of Biological and Environmental Sciences, University of Helsinki), Jesse H. Ausubel (Program for the Human Environment, The Rockefeller University), Jingyun Fang (Department of Ecology, Peking University), Alexander S. Mather (Department of Geography and Environment, University of Aberdeen), Roger A. Sedjo (Resources for the Future), and Paul E. Waggoner (Connecticut Agricultural Experiment Station)
  2. ^ "Use Energy, Get Rich and Save the Planet", The New York Times, April 20, 2009
  3. ^ Burgonio, T.J. (January 3, 2008). "Corruption blamed for deforestation". Philippine Daily Inquirer. http://newsinfo.inquirer.net/breakingnews/nation/view_article.php?article_id=110193.
  4. ^ "WRM Bulletin Number 74". World Rainforest Movement. September 2003. http://www.wrm.org.uy/bulletin/74/Uganda.html.
  5. ^ "Global Deforestation". Global Change Curriculum. University of Michigan Global Change Program. January 4, 2006. http://www.globalchange.umich.edu/globalchange2/current/lectures/deforest/deforest.html.
  6. ^ a b Alain Marcoux (August 2000). "Population and deforestation". SD Dimensions. Sustainable Development Department, Food and Agriculture Organization of the United Nations (FAO). http://www.fao.org/sd/WPdirect/WPan0050.htm.
  7. ^ Butler, Rhett A. "Impact of Population and Poverty on Rainforests". Mongabay.com / A Place Out of Time: Tropical Rainforests and the Perils They Face. http://rainforests.mongabay.com/0816.htm. Retrieved May 13, 2009.
  8. ^ Jocelyn Stock, Andy Rochen. "The Choice: Doomsday or Arbor Day". http://www.umich.edu/~gs265/society/deforestation.htm. Retrieved May 13, 2009.
  9. ^ Karen. "Demographics, Democracy, Development, Disparity and Deforestation: A Crossnational Assessment of the Social Causes of Deforestation". Paper presented at the annual meeting of the American Sociological Association, Atlanta Hilton Hotel, Atlanta, GA, Aug 16, 2003. http://www.allacademic.com/meta/p_mla_apa_research_citation/1/0/7/4/8/p107488_index.html. Retrieved May 13, 2009.
  10. ^ "The Double Edge of Globalization". YaleGlobal Online. Yale University Press. June 2007. http://yaleglobal.yale.edu/display.article?id=9366.
  11. ^ Butler, Rhett A. "Human Threats to Rainforests—Economic Restructuring". Mongabay.com / A Place Out of Time: Tropical Rainforests and the Perils They Face. http://rainforests.mongabay.com/0805.htm. Retrieved May 13, 2009.
  12. ^ Susanna B. Hecht, Susan Kandel, Ileana Gomes, Nelson Cuellar and Herman Rosa (2006). "Globalization, Forest Resurgence, and Environmental Politics in El Salvador". World Development Vol. 34, No. 2. pp. 308–323. http://www.spa.ucla.edu/cgpr/docs/sdarticle1.pdf.
  13. ^ UNFCCC (2007). "Investment and financial flows to address climate change". unfccc.int. UNFCCC. pp. 81. http://unfccc.int/files/essential_background/background_publications_htmlpdf/application/pdf/pub_07_financial_flows.pdf.
  14. ^ a b Pearce, David W (December 2001). "The Economic Value of Forest Ecosystems". Ecosystem Health, Vol. 7, no. 4. pp. 284–296. http://www.cbd.int/doc/external/academic/forest-es-2003-en.pdf.
  15. ^ Erwin H Bulte; Mark Joenje; Hans G P Jansen (2000). "Is there too much or too little natural forest in the Atlantic Zone of Costa Rica?". Canadian Journal of Forest Research; 30:3. pp. 495–506. http://article.pubs.nrc-cnrc.gc.ca/RPAS/rpv?hm=HInit&afpf=x99-225.pdf&journal=cjfr&volume=30.
  16. ^ a b c Arild Angelsen, David Kaimowitz (February 1999). "Rethinking the causes of deforestation: Lessons from economic models". The World Bank Research Observer, 14:1. Oxford University Press. pp. 73–98. http://ideas.repec.org/a/oup/wbrobs/v14y1999i1p73-98.html.
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  18. ^ Helmut J. Geist And Eric F. Lambin (February 2002). "Proximate Causes and Underlying Driving Forces of Tropical Deforestation". BioScience, Vol. 52, No. 2. pp. 143–150. http://www.freenetwork.org/resources/documents/2-5Deforestationtropical.pdf.
  19. ^ Butler, Rhett A. and Laurance, William F. (August 2008). [http://news.mongabay.com/Butler_and_Laurance-TREE.pdf "New strategies for conserving tropical forests"]. Trends in Ecology & Evolution, Vol. 23, No. 9. pp. 469–472. http://news.mongabay.com/Butler_and_Laurance-TREE.pdf.
  20. ^ Rudel, T.K. 2005 "Tropical Forests: Regional Paths of Destruction and Regeneration in the Late 20th Century" Columbia University Press
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  22. ^ "Massive deforestation threatens food security". http://www.newsfromafrica.org/newsfromafrica/articles/art_9607.html.
  23. ^ Deforestation, ScienceDaily
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  25. ^ Deforestation causes global warming, FAO
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  28. ^ http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter7.pdf IPCC Fourth Assessment Report, Working Group I Report "The Physical Science Basis", Section 7.3.3.1.5 (p. 527)
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  32. ^ a b "How can you save the rain forest. October 8, 2006. Frank Field". London. http://www.timesonline.co.uk/tol/news/article664544.ece.
  33. ^ Broeker, Wallace S. (2006). "Breathing easy: Et tu, O2." Columbia University http://www.columbia.edu/cu/21stC/issue-2.1/broecker.htm.
  34. ^ Moran, E.F., "Deforestation and Land Use in the Brazilian Amazon", Human Ecology, Vol 21, No. 1, 1993"
  35. ^ "Underlying Causes of Deforestation: UN Report". http://www.wrm.org.uy/deforestation/UNreport.html.
  36. ^ "Deforestation and Landslides in Southwestern Washington". http://www.uwec.edu/jolhm/EH2/Rogge/index.htm.
  37. ^ China's floods: Is deforestation to blame?, BBC News
  38. ^ "Underlying Causes of Deforestation: UN Report". http://www.azstarnet.com/sn/byauthor/244797.
  39. ^ "Soil, Water and Plant Characteristics Important to Irrigation". North Dakota State University.
  40. ^ http://www.actionbioscience.org/environment/nilsson.html Do We Have Enough Forests? By Sten Nilsson
  41. ^ "Deforestation". http://www.umich.edu/~gs265/society/deforestation.htm.
  42. ^ Rainforest Biodiversity Shows Differing Patterns, ScienceDaily, August 14, 2007
  43. ^ "BMBF: Medicine from the rainforest". http://www.bmbf.de/en/12484.php.
  44. ^ Single-largest biodiversity survey says primary rainforest is irreplaceable, Bio-Medicine, November 14, 2007
  45. ^ Tropical rainforests - The tropical rainforest, BBC
  46. ^ "Tropical Rainforest". http://library.thinkquest.org/11353/trforest.htm.
  47. ^ U.N. calls on Asian nations to end deforestation, Reuters
  48. ^ "Rainforest Facts". http://www.rain-tree.com/facts.htm.
  49. ^ Tropical rainforests - Rainforest water and nutrient cycles, BBC
  50. ^ Primary rainforest richer in species than plantations, secondary forests, July 2, 2007
  51. ^ Pimm, Stuart L, Russell, Gareth J, Gittleman, John L, Brooks, Thomas M. 1995 "The future of biodiversity" Science 269:5222 347-341
  52. ^ a b Timothy Charles and Whitmore, Jeffrey Sayer, 1992 "Tropical Deforestation and Species Extinction" International Union for Conservation of Nature and Natural Resources Commission on Ecology.
  53. ^ a b Pimm, Stuart L, Russell, Gareth J, Gittleman, John L, Brooks, Thomas M.1995 "The future of biodiversity" Science 269:5222 347-341
  54. ^ a b c "www.rain-tree.com/facts.htm". http://www.rain-tree.com/facts.htm.
  55. ^ Leakey, Richard and Roger Lewin, 1996, The Sixth Extinction : Patterns of Life and the Future of Humankind, Anchor, ISBN 0-385-46809-1
  56. ^ The great rainforest tragedy, The Independent
  57. ^ Biodiversity wipeout facing South East Asia, New Scientist, 23 July 2003
  58. ^ Nature loss 'to hurt global poor', BBC News, May 29, 2008
  59. ^ http://atlas.aaas.org/pdf/63-66.pdf Forest Products
  60. ^ "Destruction of Renewable Resources". http://rainforests.mongabay.com/0905.htm.
  61. ^ Deforestation Across the World's Tropical Forests Emits Large Amounts of Greenhouse Gases with Little Economic Benefits, According to a New Study at CGIAR.org, December 4, 2007
  62. ^ "New ASB Report finds deforestation offers very little money compared to potential financial benefits at ASB.CGIAR.org". http://www.asb.cgiar.org/News/default.asp?a=%7B580BF3A6-9A50-4162-B059-80CF00046F24%7D.
  63. ^ a b Flannery, T (1994). The future eaters. Melbourne: Reed Books.
  64. ^ "Clearances and Clearings: Deforestation in Mesolithic/Neolithic Britain". Oxford Journal of Archaeology. http://www3.interscience.wiley.com/journal/119153736/abstract?CRETRY=1&SRETRY=0.
  65. ^ "hand tool :: Neolithic tools -- Britannica Online Encyclopedia". http://www.britannica.com/EBchecked/topic/254115/hand-tool/39205/Neolithic-tools.
  66. ^ "Neolithic Age from 4,000 BC to 2,200 BC or New Stone Age". http://www.archaeolink.co.uk/Neolithic-Age.html.
  67. ^ C. Michael Hogan. 2007. "Knossos fieldnotes", The Modern Antiquarian
  68. ^ "www.school.eb.com/comptons/article-9310969?query=deforestation&ct=". http://www.school.eb.com/comptons/article-9310969?query=deforestation&ct=.
  69. ^ Tjeerd H. van Andel, Eberhard Zangger, Anne Demitrack, "Land Use and Soil Erosion in Prehistoric and Historical Greece' Journal of Field Archaeology 17.4 (Winter 1990), pp. 379-396
  70. ^ "The Mystery of Easter Island", Smithsonian Magazine, April 01, 2007
  71. ^ "Historical Consequences of Deforestation: Easter Island". http://www.mongabay.com/09easter_island.htm.
  72. ^ "Jared Diamond, Easter Island's End". http://www.hartford-hwp.com/archives/24/042.html.
  73. ^ In closing The Civilization of the Middle Ages: The Life and Death of a Civilization (1993) pp 564f.
  74. ^ F. Terry Norris, "Where Did the Villages Go? Steamboats, Deforestation, and Archaeological Loss in the Mississippi Valley", in Common Fields: an environmental history of St. Louis, Andrew Hurley, ed., St. Louis, MO: Missouri Historical Society Press, 1997, pp. 73-89
  75. ^ a b c d E. O. Wilson, 2002, The Future of Life, Vintage ISBN 0-679-76811-4
  76. ^ Map reveals extent of deforestation in tropical countries, guardian.co.uk, July 1, 2008
  77. ^ a b Maycock, Paul F. Deforestation. WorldBookOnline.
  78. ^ a b Ron Nielsen, The Little Green Handbook: Seven Trends Shaping the Future of Our Planet, Picador, New York (2006) ISBN 978-0312425814
  79. ^ Rainforests - Facts and information about the Rainforest.
  80. ^ Adam, David. "Global deforestation figures questioned". The Guardian. January 8, 2008.
  81. ^ "www.econlib.org/library/Enc/EnvironmentalQuality.html". http://www.econlib.org/library/Enc/EnvironmentalQuality.html.
  82. ^ Bjørn Lomborg (2001). The Skeptical Environmentalist. Cambridge: Cambridge University Press.
  83. ^ New Jungles Prompt a Debate on Rain Forests, The New York Times, January 30, 2009.
  84. ^ Intergovernmental Panel on Climate Change (2000). Land Use, Land Use Change and Forestry. Cambridge University Press.[page needed]
  85. ^ Frederic Achard, Hugh D Eva, Hans-Jurgen Stibig, Philippe Mayaux (2002). "Determination of deforestation rates of the world's humid tropical forests." Science 297:5583: pp. 999-1003.
  86. ^ Jha, Alok. "Amazon rainforest vanishing at twice rate of previous estimates". The Guardian. October 21, 2005.
  87. ^ Satellite images reveal Amazon forest shrinking faster, csmonitor.com
  88. ^ http://www.aseanenvironment.info/Abstract/41014849.pdf Deforestation and the environmental Kuznets curve:An institutional perspective
  89. ^ Environmental Economics: A deforestation Kuznets curve?, November 22, 2006
  90. ^ "Is there an environmental Kuznets curve for deforestation?". http://ideas.repec.org/a/eee/deveco/v58y1999i1p231-244.html.
  91. ^ "Pan-tropical Survey of Forest Cover Changes 1980-2000". Forest Resources Assessment. Rome, Italy: Food and Agriculture Organization of the United Nations (FAO). http://www.fao.org/docrep/004/y1997e/y1997e1f.htm.
  92. ^ "www.fao.org/DOCREP/MEETING/003/X9591E.HTM". http://www.fao.org/DOCREP/MEETING/003/X9591E.HTM.
  93. ^ Worldwatch: Wood Production and Deforestation Increase & Recent Content, Worldwatch Institute
  94. ^ a b "World deforestation rates and forest cover statistics, 2000-2005". http://news.mongabay.com/2005/1115-forests.html.
  95. ^ The fear is that highly diverse habitats, such as tropical rainforest, are vanishing at a faster rate that is partly masked by the slower deforestation of less biodiverse, dry, open forests. Because of this omission, the most harmful impacts of deforestation (such as habitat loss) could be increasing despite a possible decline in the global rate of deforestation.
  96. ^ "Remote sensing versus self-reporting". http://news.mongabay.com/2008/0629-deforestation.html.
  97. ^ The World Bank estimates that 80% of logging operations are illegal in Bolivia and 42% in Colombia, while in Peru, illegal logging accounts for 80% of all logging activities. (World Bank (2004). Forest Law Enforcement.) (The Peruvian Environmental Law Society (2003). Case Study on the Development and Implementation of Guidelines for the Control of Illegal Logging with a View to Sustainable Forest Management in Peru.)
  98. ^ "National Geographic: Eye in the Sky—Deforestation". http://www.nationalgeographic.com/eye/deforestation/effect.html.
  99. ^ "Rainforests & Agriculture". http://www.csupomona.edu/~admckettrick/projects/ag101_project/html/size.html.
  100. ^ The Amazon Rainforest, BBC
  101. ^ "The Causes of Tropical Deforestation". http://www.ru.org/ecology-and-environment/the-causes-of-tropical-deforestation.html.
  102. ^ "What is Deforestation?". http://kids.mongabay.com/lesson_plans/lisa_algee/deforestation.html.
  103. ^ IUCN - Three new sites inscribed on World Heritage List, June 27, 2007
  104. ^ "Madagascar's rainforest". http://www.newscientist.com/data/images/archive/1717/17173001.jpg.
  105. ^ "International Conference on Reforestation and Environmental Regeneration of Haiti". http://www.satglobal.com/cfpap2.htm.
  106. ^ "Chart - Tropical Deforestation by Country & Region". http://www.mongabay.com/deforestation_rate_tables.htm.
  107. ^ "Rainforest Destruction". http://www.rainforestweb.org/Rainforest_Destruction/.
  108. ^ Amazon deforestation rises sharply in 2007, USATODAY.com, January 24, 2008
  109. ^ "Rainforest loss shocks Brazil". http://www.guardian.co.uk/brazil/story/0,,1488468,00.html.
  110. ^ "Copenhagen Accord of 18 December 2009". UNFCC. 2009. http://unfccc.int/files/meetings/cop_15/application/pdf/cop15_cph_auv.pdf. Retrieved 2009-12-28.
  111. ^ "Methodological Guidance". UNFCC. 2009. http://unfccc.int/files/na/application/pdf/cop15_ddc_auv.pdf. Retrieved 2009-12-28.
  112. ^ Diamond, Jared Collapse: How Societies Choose To Fail or Succeed; Viking Press 2004, pages 301-302
  113. ^ Diamond, pages 320-331
  114. ^ "State of the World's Forests 2009". United Nations Food and Agriculture Organization.
  115. ^ Jonathan A Foley, Ruth DeFries, Gregory P Asner, Carol Barford, et al. 2005 "Global Consequences of Land Use" Science 309:5734 570-574
  116. ^ a b James Owen, 2006, "World's Forests Rebounding, Study Suggests" National Geographic News http://news.nationalgeographic.com/news/2006/11/061113-forests.html
  117. ^ John Gittings, 2001, "Battling China's deforestation" World News http://www.guardian.co.uk/world/2001/mar/20/worlddispatch.china
  118. ^ "World Intact Forests campaign by Greenpeace". http://www.intactforests.org.
  119. ^ World forest cover map
  120. ^ "Alternative thematic map by Howstuffworks; in pdf" (PDF). http://static.howstuffworks.com/gif/maps/pdf/WOR_THEM_Forests.pdf.
  121. ^ No Man's Garden Daniel B. Botkin p 246-247
  122. ^ Sample, Ian. "Forests are poised to make a comeback, study shows". The Guardian. November 14, 2006.
  123. ^ Nicholas Balabkins, "Germany Under Direct Controls; Economic Aspects Of Industrial Disarmament 1945-1948, Rutgers University Press, 1964. p. 119. The two quotes used by Balabkins are referenced to respectively; U.S. office of Military Government, A Year of Potsdam: The German Economy Since the Surrender (1946), p.70; and U.S. Office of Military Government, The German Forest Resources Survey (1948), p. II. For similar observations see G.W. Harmssen, Reparationen, Sozialproduct, Lebensstandard (Bremen: F. Trujen Verlag, 1948), I, 48
  124. ^ "Encyclopedia of World Environmental History". Routledge, 2004. ISBN 0415937337
  125. ^ Patricia Marchak, "Logging the Globe" p. 157
  126. ^ "Okinawan History and Karate-do". http://www.nyc-shorinryu.com/okinawa.html.
General references
Ethiopia deforestation references
  • Parry, J. (2003). Tree choppers become tree planters. Appropriate Technology, 30(4), 38-39. Retrieved November 22, 2006, from ABI/INFORM Global database. (Document ID: 538367341).
  • Hillstrom, K & Hillstrom, C. (2003). Africa and the Middle east. A continental Overview of Environmental Issues. Santabarbara, CA: ABC CLIO.
  • Williams, M. (2006). Deforesting the earth: From prehistory to global crisis: An Abridgment. Chicago: The university of Chicago Press.
  • Mccann. J.C. (1990). A Great Agrarian cycle? Productivity in Highland Ethiopia, 1900 To 1987. Journal of Interdisciplinary History, xx: 3,389-416. Retrieved November 18, 2006, from JSTOR database.



Mangrove

Pneumatophores penetrate the sand surrounding a mangrove tree.

Mangroves are trees and shrubs that grow in saline coastal habitats in the tropics and subtropics – mainly between latitudes 25° N and 25° S. The saline conditions tolerated by various species range from brackish water, through pure seawater (30 to 40 ppt), to water of over twice the salinity of ocean seawater, where the salt has become concentrated by evaporation (up to 90 ppt).[1][2]

There are many species of trees and shrubs adapted to saline conditions. Not all are closely related, and the term "mangrove" may be used for all of them, or more narrowly only for the mangrove family of plants, the Rhizophoraceae, or even more specifically just for mangrove trees of the genus Rhizophora.

Mangroves form a characteristic saline woodland or shrubland habitat, called mangrove swamp, mangrove forest, mangrove or mangal.[3] Mangals are found in depositional coastal environments where fine sediments (often with high organic content) collect in areas protected from high energy wave action. They occur both in estuaries and along open coastlines. Mangroves dominate three quarters of tropical coastlines.[2]

Contents

Ecology

{{biome}

 This section needs attention from an expert on the subject. See the talk page for details. WikiProject Ecology or the Ecology Portal may be able to help recruit an expert. (February 2009)

Mangals are found in tropical and sub-tropical tidal areas, and as such have a high degree of salinity. Areas where mangals occur include estuaries and marine shorelines.[1]

Plants in mangals are diverse but all are able to exploit their habitat (the intertidal zone) by developing physiological adaptations to overcome the problems of anoxia, high salinity and frequent tidal inundation. About 110 species belong to the mangal.[1] Each species has its own solutions to these problems; this may be the primary reason why, on some shorelines, mangrove tree species show distinct zonation. Small environmental variations within a mangal may lead to greatly differing methods for coping with the environment. Therefore, the mix of species is partly determined by the tolerances of individual species to physical conditions, like tidal inundation and salinity, but may also be influenced by other factors such as predation of plant seedlings by crabs.

Once established, mangrove roots provide an oyster habitat and slow water flow, thereby enhancing sediment deposition in areas where it is already occurring. The fine, anoxic sediments under mangroves act as sinks for a variety of heavy (trace) metals which colloidal particles in the sediments scavenged from the water. Mangrove removal disturbs these underlying sediments, often creating problems of trace metal contamination of seawater and biota.

Mangroves protect coastal areas from erosion, storm surge (especially during hurricanes), and tsunamis.[4][5] The mangrove's massive root system is efficient at dissipating wave energy.[6] Likewise, they slow down tidal water enough that its sediment is deposited as the tide comes in, leaving all except fine particles when the tide ebbs.[7] In this way, mangroves build their own environment.[4] Because of the uniqueness of mangrove ecosystems and the protection against erosion that they provide, they are often the object of conservation programs including national Biodiversity Action Plans.[5]

However, mangroves' protective value is sometimes overstated. Wave energy is typically low in areas where mangroves grow,[8] so their effect on erosion can only be measured over long periods.[6] Their capacity to limit high-energy wave erosion is limited to events like storm surges and tsunamis.[9] Erosion often occurs on the outer sides of bends in river channels that wind through mangroves, while new stands of mangroves are appearing on the inner sides where sediment is accreting.[citation needed]

The unique ecosystem found in the intricate mesh of mangrove roots offers a quiet marine region for young organisms. In areas where roots are permanently submerged, the organisms they host include algae, barnacles, oysters, sponges, and bryozoans, which all require a hard surface for anchoring while they filter feed. Shrimps and mud lobsters use the muddy bottom as their home.[10] Mangrove crabs mulch the mangrove leaves, adding nutritients to the mangal muds for other bottom feeders.[11] In at least some cases, export of carbon fixed in mangroves is important in coastal food webs.

Mangrove plantations in Vietnam, Thailand, the Philippines and India host several commercially important species of fish and crustaceans. Despite restoration efforts, developers and others have removed over half of the world's mangroves in recent times.

Biology

Of the recognized 110 mangrove species, only about 54 species in 20 genera from 16 families constitute the "true mangroves", species that occur almost exclusively in mangrove habitats.[3] Demonstrating convergent evolution, many of these species found similar solutions to the tropical conditions of variable salinity, tidal range (inundation), anaerobic soils and intense sunlight. Plant biodiversity is generally low in a given mangal.[1] This is especially true in higher latitudes and in the Americas. The greatest biodiversity occurs in the mangal of New Guinea, Indonesia and Malaysia.[12]

Adaptations to low oxygen

A red mangrove, Rhizophora mangle
Above and below water view at the edge of the mangal

Red mangroves, which can survive in the most inundated areas, prop themselves above the water level with stilt roots and can then absorb air through pores in their bark (lenticels). Black mangroves live on higher ground and make many pneumatophores (specialised root-like structures which stick up out of the soil like straws for breathing) which are also covered in lenticels. These "breathing tubes" typically reach heights of up to thirty centimeters, and in some species, over three meters. There are four types of pneumatophore—stilt or prop type, snorkel or peg type, knee type, and ribbon or plank type. Knee and ribbon types may be combined with buttress roots at the base of the tree. The roots also contain wide aerenchyma to facilitate oxygen transport within the plant.

Salt crystals formed on grey mangrove leaf

Limiting salt intake

Red mangroves exclude salt by having significantly impermeable roots which are highly suberised, acting as an ultra-filtration mechanism to exclude sodium salts from the rest of the plant. Analysis of water inside mangroves has shown that 90% to 97% of salt has been excluded at the roots. Salt which does accumulate in the shoot concentrates in old leaves which the plant then sheds. Red mangroves can also store salt in cell vacuoles. White (or grey) mangroves can secrete salts directly; they have two salt glands at each leaf base (hence their name—they are covered in white salt crystals).

Limiting water loss

Because of the limited freshwater availability in salty intertidal soils, mangroves limit the amount of water that they lose through their leaves. They can restrict the opening of their stomata (pores on the leaf surfaces, which exchange carbon dioxide gas and water vapour during photosynthesis). They also vary the orientation of their leaves to avoid the harsh midday sun and so reduce evaporation from the leaves. Anthony Calfo, a noted aquarium author, observed anecdotally that a red mangrove in captivity only grows if its leaves are misted with fresh water several times a week, simulating the frequent tropical rainstorms.[13]

Nutrient uptake

The biggest problem that mangroves face is nutrient uptake. Because the soil is perpetually waterlogged, there is little free oxygen. Anaerobic bacteria liberate nitrogen gas, soluble iron, inorganic phosphates, sulfides, and methane, which makes the soil much less nutritious and contributes to mangroves' pungent odor. Prop root systems allow mangroves to absorb gases directly from the atmosphere, and other nutrients such as iron, from the inhospitable soil. Mangroves store gases directly inside the roots, processing them even when the roots are submerged during high tide.

Increasing survival of offspring

Red mangrove seeds germinate while still on the parent tree

In this harsh environment, mangroves have evolved a special mechanism to help their offspring survive. Mangrove seeds are buoyant and therefore suited to water dispersal. Unlike most plants, whose seeds germinate in soil, many mangroves (e.g. Red Mangrove) are viviparous, whose seeds germinate while still attached to the parent tree. Once germinated, the seedling grows either within the fruit (e.g. Aegialitis, Avicennia and Aegiceras), or out through the fruit (e.g. Rhizophora, Ceriops, Bruguiera and Nypa) to form a propagule (a ready-to-go seedling) which can produce its own food via photosynthesis. The mature propagule then drops into the water which can transport it great distances. Propagules can survive desiccation and remain dormant for over a year before arriving in a suitable environment. Once a propagule is ready to root, its density changes so that the elongated shape now floats vertically rather than horizontally. In this position, it is more likely to lodge in the mud and root. If it does not root, it can alter its density and drift again in search of more favorable conditions.

Taxonomy

The following listing (modified from Tomlinson, 1986) gives the number of species of mangroves in each listed plant genus and family.

Major components

Family Genus, number of species Common name
Acanthaceae, Avicenniaceae or Verbenaceae
(family allocation disputed)		 Avicennia, 9 Black mangrove
Combretaceae Conocarpus, 1; Laguncularia, 11; Lumnitzera, 2 Buttonwood, White mangrove
Arecaceae Nypa, 1 Mangrove palm
Rhizophoraceae Bruguiera, 6; Ceriops, 2; Kandelia, 1; Rhizophora, 8 Red mangrove
Lythraceae Sonneratia, 5 Mangrove apple

Minor components

Family Genus, number of species
Acanthaceae Acanthus, 1; Bravaisia, 2
Bombacaceae Camptostemon, 2
Cyperaceae Fimbristylis, 1
Euphorbiaceae Excoecaria, 2
Lecythidaceae Barringtonia, 6
Lythraceae Pemphis, 1
Meliaceae Xylocarpus, 2
Myrsinaceae Aegiceras, 2
Myrtaceae Osbornia, 1
Pellicieraceae Pelliciera, 1
Plumbaginaceae Aegialitis, 2
Pteridaceae Acrostichum, 3
Rubiaceae Scyphiphora, 1
Sterculiaceae Heritiera, 3

Geographical regions

Mangroves occur in numerous areas worldwide. See List of mangrove ecoregions.

Africa

Mangrove near the town of Cienaga, Magdalena, in the Ciénaga Grande de Santa Marta swampy marshes
A cluster of mangroves on the banks of the Vellikeel River in Kannur District of Kerala, India
Mangroves in Mangalavanam Bird Sanctuary of Kerala, India
The green tunnel of mangrove in Sihcao, Tainan, Taiwan
A mangrove of the genus Sonneratia, showing abundant pneumatophores growing on the landward margin of the reef flat on Yap

There are important mangrove swamps in Kenya and Madagascar, with the latter even admixing at the coastal verge with dry deciduous forests.

Nigeria has Africa's largest mangrove concentration, spanning 36,000 km2. Oil spills and leaks have destroyed many in the last fifty years, damaging the local fishing economy and water quality.[14]

Along the coast of the Red Sea both on the Egyptian side and in the Gulf of Aqaba, mangroves composed primarily of Avicennia marina and Rhyzophora mucronata in about 28 stands cover about 525 hectares.[citation needed] Almost all Egyption mangrove stands are now protected.[citation needed]

Americas

Mangroves live in many parts of the tropical and subtropical coastal zones of North, South and Central America.

Continental United States

Because of their sensitivity to sub-freezing temperatures, mangroves in the continental United States are limited to the Florida peninsula (see Florida mangroves) and isolated growths[15] of Black Mangrove (Avicennia germinans) along the coast of southern Louisiana[16] and south Texas[17]

Central America & Caribbean

Mangroves occur on the west coast of Costa Rica, on the Pacific and Caribbean coasts of Nicaragua, Belize, Guatemala, Honduras, and Panama and on many Caribbean Islands, such as Curacao, Bonaire, Antigua, the Bahamas, Saint Kitts and Nevis and St. Lucia. Significant mangals include the Marismas Nacionales-San Blas mangroves in Mexico. Mangroves can also be found in Puerto Rico, Cuba, the Dominican Republic, Haiti, Jamaica, Trinidad, Barbados, and the Pacific coast of El Salvador.

[edit] South America

Brazil contains approximately 26,000 km2 of mangals, 15% of the world's total of 172,000 km2.

Ecuador and Peru have significant areas of mangroves mainly in the Gulf of Guayaquil-Tumbes mangroves.

Venezuela's northern Caribbean island, Margarita, possesses mangrove forests in the Parque Nacional la Restinga.

Colombia possesses large mangrove forests on both its Caribbean and Pacific coasts.

Asia

Indomalaya ecozone

Mangroves occur on Asia's south coast, throughout the Indian subcontinent, in all southeast Asian countries, and on islands in the Indian Ocean, Arabian Sea, Bay of Bengal, South China Sea and the Pacific.

The mangal is particularly prevalent in the deltas of large Asian rivers. The Sundarbans is the largest mangrove forest in the world, located in the Ganges delta in Bangladesh and West Bengal, India.

The Pichavaram Mangrove Forest near Chidambaram, South India, by the Bay of Bengal is the world's second largest mangrove forest. Notably, it has actually increased by 90% in size between 1986 and 2002.[citation needed]

Major mangals live on the Andaman and Nicobar Islands and the Gulf of Kutch in Gujarat.[18]

Other significant mangals include the Bhitarkanika Mangroves and Godavari-Krishna mangroves.

The mangal in the Ganges-Surma-Meghna River System delta was one of the largest in the world.[citation needed]

In Vietnam, mangrove forests grow along the southern coast, including two forests: the Can Gio Mangrove Forest biosphere reserve and the U Minh mangrove forest in the Sea and Coastal Region of Kien Giang, Ca Mau and Bac Lieu province.

The mangrove forests of Kompong Sammaki in Cambodia are of major ecological and cultural importance, as the human population relies heavily on the crabs and fish that live in the roots.

The three most important mangrove forests of Taiwan are: Tamsui River in Taipei, Jhonggang River in Miaoli and the Sihcao Wetlands in Tainan. According to research, there are four existing types of mangrove in Taiwan.[citation needed] Some places have been developed as scenic areas, such as the log raft routes in Sihcao.

In the Indonesian Archipelago, mangroves occur around much of Sumatra, Borneo, Sulawesi and the surrounding islands. While further north they found along the coast of the Malay Peninsula.

Pakistan

Pakistani mangroves are located mainly on the Indus delta. Major mangrove forests are also found on the coastal line of provinces Sindh and Balochistan.

In Pakistan, the mangrove forest are located on the coasts of Sindh and Balochistan provinces. Pakistan's mangrove ecosystem is one of the largest found in an arid climate. Without realising their global significance, the local communities continue to use mangroves as fuelwood and fodder. In urban areas, mangroves are being cut away for developmental activities on the coast. Pakistan project include rehabilitation of mangrove-degraded areas at Sonmiani and Jiwani in Balochistan, and Sandspit in Karachi, Sindh. In Karachi, land reclamation projects are cutting down mangrove forests and filling then earth and selling them for commercial and urban development.

Middle East

Oman, near Muscat, supports large areas of mangroves, in particular at Shinas, Qurm Park and Mahout Island. In Arabic, mangrove trees are known as qurm, thus the mangrove area in Oman is known as Qurm Park. Mangroves are also present extensively in neighboring Yemen.[19]

Iranian mangrove forests occur between 25°11′N to 27°52′N. These forests exist in the north part of the Persian Gulf and Oman Sea, along three Maritime Provinces in the south of Iran. These provinces respectively from southwest to southeast of Iran, include Bushehr, Hormozgan and Sistan & Balouchestan.

Australasia

More than fifty species of Rhizophoraceae grow in Australasia[20] with particularly high biodiversity on the island of New Guinea and northern Australia.[20]

Australia has approximately 11,500 km2 of mangroves primarily on the northern and eastern coasts of the continent, with occurrences as far south as Millers Landing in Wilsons Promontory, Victoria[21] (38°54′S)[22] and Barker Inlet in Adelaide, South Australia.[23]

New Zealand also has mangrove forests extending to around 38°S (similar to Australia's southernmost mangrove incidence): the furthest geographical extent on the west coast is Raglan Harbour (37°48′S); on the east coast, Ohiwa Harbour (near Opotiki) is the furthest south that mangroves are found (38°00′S).[24]

Pacific islands

Twenty-five species of mangrove are found on various Pacific islands, with extensive mangals on some islands. Mangals on Guam, Palau, Kosrae and Yap have been badly affected by development.[25]

Mangroves are not native to Hawaii, but the Red mangrove, Rhizophora mangle, and Oriental mangrove, Bruguiera sexangula, have been introduced and are now naturalized.[26] Both species are classified as pests by the University of Hawaii Botany Department.[27]

Cultivating mangroves

Red mangroves are the most common choice, used particularly in marine aquariums in a sump to reduce proteins and other minerals in the water. Mangroves also appear in home aquariums, and as ornamental plants, such as in Japan.

Exploitation and conservation

The United Nations Environment Program estimated that shrimp farming causes a quarter of the destruction of mangrove forests.[28]

Grassroots efforts to save mangroves from development are becoming more popular as the benefits of mangroves become more widely known. In the Bahamas, for example, active efforts to save mangroves are occurring on the islands of Bimini and Great Guana Cay. In Trinidad and Tobago as well, efforts are underway to protect a mangrove threatened by the construction of a steelmill and a port.[29] In Thailand, community management has been effective in restoring damaged mangroves.[30]

Approximately 35% of mangrove area was lost during the last several decades of the twentieth century (in countries for which sufficient data exist, which encompass about half of the area of mangroves).[31]

It has been cited that Mangroves can help buffer against Tsunami, cyclones, and other storms. One village in Tamil Nadu was protected from Tsunami destruction - the villagers in Naluvedapathy planted 80,244 saplings in order to get into the Guinness Book of World Records. This created a kilometre wide belt of trees of various varieties. When the Tsunami struck, much of the land around the village was flooded, but the village itself suffered minimal damage.[32][33]

In popular media

  • The mangrove is used as a symbol in Annie Dillard's essay Sojourner due to its significance as a self-sustaining biome.
  • The manga series One Piece features a forest of giant mangroves that form the Sabaody Archipelago. The mangroves produce a resin that combines with the oxygen exhaled by the trees to create large bubbles. The local population uses the bubbles for everything from transport to hotels.

Notes

  1. ^ a b c d Mangal (Mangrove). World Vegetation. Mildred E. Mathias Botanical Garden, University of California at Los Angeles
  2. ^ a b Morphological and Physiological Adaptations: Florida mangrove website
  3. ^ a b Hogarth, Peter J. (1999). The Biology of Mangroves Oxford University Press, Oxford.
  4. ^ a b Mazda, Y.; Kobashi, D. and Okada, S. (2005) "Tidal-Scale Hydrodynamics within Mangrove Swamps" Wetlands Ecology and Management 13(6): pp. 647-655
  5. ^ a b Danielsen, F. et al. (2005) "The Asian tsunami: a protective role for coastal vegetation" Science 310: p. 643.
  6. ^ a b Massel, S. R.; Furukawa, K.and Brinkman R. M. (1999) "Surface wave propagation in mangrove forests" Fluid Dynamics Research 24(4): pp. 219–249
  7. ^ Mazda, Yoshihiro et al. (1997) "Drag force due to vegetation in mangrove swamps" Mangroves and Salt Marshes 1: pp. 193–199
  8. ^ Baird, Andrew (26 December 2006) "False Hopes and Natural Disasters" New York Times editorial
  9. ^ Dahdouh-Guebas, F. et al. (2005) "How effective were mangroves as a defence against the recent tsunami?" Current Biology 15(12): pp. 443–447
  10. ^ Encarta Encyclopedia 2005. Article — Seashore, by Heidi Nepf.
  11. ^ Skov, Martin W. and Hartnoll, Richard G. (March 2002). Paradoxical selective feeding on a low-nutrient diet: why do mangrove crabs eat leaves? Oecologia 131(1): pp. 1–7.
  12. ^ UN Report on mangrove diversity
  13. ^ Calfo, Anthony (2006). Mangroves for the Marine Aquarium.
  14. ^ O'Neill.T (February 2007). "Curse of the Black Gold". National Geographic: 88 to 117.
  15. ^ "Modeling Hurricane Effects on Mangrove Ecosystems" U.S. Geological Survey, USGS FS-095-97, June 1997
  16. ^ "Coastal Mangrove-Marsh Shrubland" (PDF). Conservation Habitats & Species Assessments. Louisiana Department of Wildlife & Fisheries. December 2005. http://www.wlf.state.la.us/pdfs/experience/Coastal%20Mangrove-Marsh%20Shrubland.pdf.
  17. ^ Yang, Chenghai; Everitt, James; Fletcher, Reginald; Jensen, Ryan;Mausel, Paul (2008-03-15). "Mapping Black Mangrove Along the South Texas Gulf Coast Using AISA+ Hyperspectral Imagery". Biennial Workshop on Aerial Photography, Videography, and High Resolution Digital Imagery for Resource Assessment Proceedings (American Society for Photogrammetry and Remote Sensing). http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=213366.
  18. ^ Mangroves of India - URL retrieved November 26, 2006
  19. ^ Rouphael, Tony ;Turak, Emre and Brodie, Jon (1992) "Chapter 3: Seagrasses and Mangroves of Yemen's Red Sea" In DouAbal, A. et al. (editors) (1992) Protection of Marine Ecosystems of the Red Sea Coast of Yemen Global Environment Facility, United Nations Development Programme, New York, pp. 41-49
  20. ^ a b Food and Agriculture Organization of the United Nations (FAO) (2007) The world's mangroves, 1980-2005: a thematic study in the framework of the Global Forest Resources Assessment 2005 (FAO forestry paper #153 ) Rome,page 37, ISBN 978-92-5-105856-5
  21. ^ "Millers Landing". Victorian Resources Online:West Gippsland. Department of Primary Industries.. http://www.ga.gov.au/bin/gazd01?rec=248996. Retrieved 2009-03-30.
  22. ^ "Millers Landing". Geoscience Australia Place Names Search. Australian Government. http://www.ga.gov.au/bin/gazd01?rec=248996. Retrieved 2009-03-30.
  23. ^ Zann, Leon P. (1996) [1995]. "Mangrove ecosystems in Australia: structure, function and status". State of the Marine Environment Report for Australia. Australian Government, Dept of Environment and Heritage. ISBN. ISBN 0-642-17399-0. http://www.deh.gov.au/coasts/publications/somer/annex1/mangrove.html. Retrieved 2006-11-25.
  24. ^ Mangroves and Seagrasses - Treasures of the Sea
  25. ^ Hawaii and the Pacific Islands
  26. ^ Allen, James A. and Krauss, Ken W. (2006) "Influence of Propagule Flotation Longevity and Light Availability on Establishment of Introduced Mangrove Species in Hawai'i". Pacific Science 60:3, July 2006. Abstract at [1] - URL retrieved November 28, 2006.
  27. ^ Hawaiian Alien Plant Studies - URL retrieved November 28, 2006.
  28. ^ Botkin, D. and E. Keller (2003) Enrivonmental Science: Earth as a living planet (p.2) John Wiley & Sons. ISBN 0-471-38914-5
  29. ^ http://www.thepetitionsite.com/petition/957999809
  30. ^ http://ecotippingpoints.org/our-stories/indepth/thailand-mangrove-restoration-community-management.html
  31. ^ Millennium Ecosystem Assessment (2005) Ecosystems and Human Well-being: Synthesis (p.2) Island Press, Washington, DC. World Resources Institute ISBN 1-59726-040-1
  32. ^ Tree News, Spring/Summer 2005,Publisher Felix Press
  33. ^ Mangrove India website

See also

References

  • Saenger, Peter (2002). Mangrove Ecology, Silviculture, and Conservation. Kluwer Academic Publishers, Dordrecht. ISBN 1-4020-0686-1.
  • Hogarth, Peter J. (1999). The Biology of Mangroves. Oxford University Press, Oxford. ISBN 0-19-850222-2.
  • Thanikaimoni, Ganapathi (1986). Mangrove Palynology UNDP/UNESCO and the French Institute of Pondicherry, ISSN 0073-8336 (E).
  • Tomlinson, Philip B. (1986). The Botany of Mangroves. Cambridge University Press, Cambridge, ISBN 0-521-25567-8.
  • Teas, H. J. (1983). Biology and Ecology of Mangroves. W. Junk Publishers, The Hague. ISBN 90-6193-948-8.
  • Plaziat, J.C., et al. (2001). "History and biogeography of the mangrove ecosystem, based on a critical reassessment of the paleontological record". Wetlands Ecology and Management 9 (3): pp. 161–179.
  • Sato, Gordon; Riley, Robert; et al. Growing Mangroves With The Potential For Relieving Regional Poverty And Hunger WETLANDS, Vol. 25, No. 3 – September 2005
  • Jayatissa, L. P., Dahdouh-Guebas, F. & Koedam, N. (2002). "A review of the floral composition and distribution of mangroves in Sri Lanka". Botanical Journal of the Linnean Society 138: 29–43.
  • Warne, K. (February 2007). "Forests of the Tide". National Geographic pp. 132–151
  • Aaron M. Ellison (2000) "Mangrove Restoration: Do We Know Enough?" Restoration Ecology 8 (3), 219–229 doi: 10.1046/j.1526-100x.2000.80033.x
  • Agrawala, Shardul; Hagestad; Marca; Koshy, Kayathu; Ota, Tomoko; Prasad, Biman; Risbey, James; Smith, Joel; Van Aalst, Maarten. 2003. Development and Climate Change in Fiji: Focus on Coastal Mangroves. Organisation of Economic Co-operation and Development, Paris, Cedex 16, France.
  • Barbier, E.B., Sathirathai, S., 2001. Valuing Mangrove Conservation in Southern Thailand. Contemproary Economic Policy. 19 (2) 109–122.
  • Bosire, J.O., Dahdouh-Guebas, F., Jayatissa, L.P., Koedam, N., Lo Seen, D., Nitto, Di D. 2005. How Effective were Mangroves as a Defense Against the Recent Tsunami? Current Biology Vol. 15 R443-R447.
  • Bowen, Jennifer L., Valiela, Ivan, York, Joanna K. 2001. Mangrove Forests: One of the World's Threatened Major Tropical Environments. Bio Science 51:10, 807–815.
  • Jin-Eong, Ong. 2004. The Ecology of Mangrove Conservation and Management. Hydrobiologia. 295:1-3, 343–351.
  • Glenn, C. R. 2006. "Earth's Endangered Creatures" (Online). Accessed 4/28/2008 at http://earthsendangered.com.
  • Lewis, Roy R. III. 2004. Ecological Engineering for Successful Management and Restoration of Mangrove Forest. Ecological Engineering. 24:4, 403–418.
  • Lucien-Brun H. 1997. Evolution of world shrimp production: Fisheries and aquaculture. World Aquaculture. 28:21–33.
  • Twilley, R. R., V.H. Rivera-Monroy, E. Medina, A. Nyman, J. Foret, T. Mallach, and L. Botero. 2000. Patterns of forest development in mangroves along the San Juan River estuary, Venezuela. Forest Ecology and Management.





Coral bleaching

Bleached corals
Healthy corals

Coral bleaching is the whitening of corals, due to stress-induced expulsion or death of symbiotic, algae-like protozoa, or due to the loss of pigmentation within the protozoa.[1] The corals that form the structure of the great reef ecosystems of tropical seas depend upon a symbiotic relationship with unicellular flagellate protozoa, called zooxanthellae, that are photosynthetic and live within their tissues. Zooxanthellae give coral its coloration, with the specific color depending on the particular clade. Under stress, corals may expel their zooxanthellae, which leads to a lighter or completely white appearance, hence the term "bleached".[2]

Once bleaching begins, it tends to continue even without continuing stress. If the coral colony survives the stress period, zooxanthellae often require weeks to months to return to normal density.[3] The new residents may be of a different species. Some species of zooxanthellae and corals are more resistant to stress than other species.

Contents

Causes of coral bleaching

Coral bleaching is a vivid sign of corals responding to stress, which can be induced by any of:

Temperature change

Unbleached (left) and bleached (right) coral

Temperature change is the most common cause of coral bleaching.[4]

Large coral colonies such as Porites are able to withstand extreme temperature shocks, while fragile branching corals such as table coral are far more susceptible to stress following a temperature change.[10] Corals consistently exposed to low stress levels may be more resistant to bleaching.

Factors that influence the outcome of a bleaching event include stress-resistance which reduces bleaching, tolerance to the absence of zooxanthellae, and how quickly new coral grows to replace the dead. Due to the patchy nature of bleaching, local climatic conditions such as shade or a stream of cooler water can reduce bleaching incidence. Coral and zooxanthellae health and genetics also influence bleaching.[11]

Monitoring reef sea surface temperature

The US National Oceanic and Atmospheric Administration (NOAA) monitors for bleaching "hot spots", areas where sea surface temperature rises 1 degree Celsius or more above the long-term monthly average. This system detected the worldwide 1998 bleaching event,[12][13] that corresponded to an El Niño. NOAA also uses a satellite with 50k resolution at night, which some argue covers too large a spatial area and does not detect the maximum sea surface temperatures occurring usually around noon.[citation needed]

Changes in ocean chemistry

Increasing ocean acidification likely exacerbates the bleaching effects of thermal stress.[14]

Infectious disease

Bioerosion (coral damage) such as this may be caused by coral bleaching.[15]

It was discovered in 1996 that the bleaching agent of Oculina patagonica in the Mediterranean Sea was infectious bacteria attacking the zooxanthellae.[16] The bacteria were later identified as Vibrio shiloi.[14] V. shiloi is infectious only during warm periods. Elevated temperature increases the virulence of V. shiloi, which then become able to adhere to a beta-galactoside-containing receptor in the surface mucus of the host coral.[14][17] V. shiloi then penetrates the coral's epidermis, multiplies, and produces both heat-stable and heat-sensitive toxins, which affect zooxanthellae by inhibiting photosynthesis and causing lysis.

During the summer of 2003, coral reefs in the Mediterranean Sea appeared to gain resistance to the pathogen, and further infection was not observed.[18] The main hypothesis for the emerged resistance is the presence of symbiotic communities of protective bacteria living in the corals. The bacterial species capable of lysing V. shiloi has not been identified.

Impact

In the 2010-2040 period, coral reefs are expected to become highly susceptible to more frequent bleaching events. The IPCC sees this as the greatest threat to the world's reef systems.[19][20][21][22]

Great Barrier Reef

Two images of the Great Barrier Reef showing that the warmest water (top picture) coincides with the coral reefs (lower picture), setting up conditions that can cause coral bleaching.

The Great Barrier Reef along the coast of Australia experienced bleaching events in 1980, 1982, 1992, 1994, 1998, 2002, and 2006.[22] While most areas recovered with relatively low levels of coral death, some locations suffered severe damage, with up to 90% of corals killed.[7] The most widespread and intense events occurred in the summers of 1998 and 2002, affecting about 42% and 54% of reefs, respectively.[23][24]

The IPCC's moderate warming scenarios (B1 to A1T, 2°C by 2100, IPCC, 2007, Table SPM.3, p. 13[25]) forecast that corals on the Great Barrier Reef are very likely to regularly experience summer temperatures high enough to induce bleaching.[23]

Other areas

Other coral reef provinces have been permanently damaged by warm sea temperatures, most severely in the Indian Ocean. Up to 90% of coral cover has been lost in the Maldives, Sri Lanka, Kenya and Tanzania and in the Seychelles.[citation needed]

Evidence from extensive research in the 1970’s of thermal tolerance in Hawaiian corals and of oceanic warming led researchers in 1990 to predict mass occurrences of coral bleaching throughout Hawaii. Major bleaching occurred in 1996 and in 2002.[26]

Coral in the south Red Sea does not bleach despite summer water temperatures up to 34°C.[citation needed]

Significant bleaching occurred in the Mediterranean Sea in 1996.[citation needed]

See also

Notes

  1. ^ Dove SG, Hoegh-Guldberg O (2006). "Coral bleaching can be caused by stress. The cell physiology of coral bleaching". in Ove Hoegh-Guldberg; Jonathan T. Phinney; William Skirving; Joanie Kleypas. Coral Reefs and Climate Change: Science and Management. [Washington]: American Geophysical Union. pp. 1–18. ISBN 0-87590-359-2.
  2. ^ Hoegh-Guldberg O (1999). "Climate change, coral bleaching and the future of the world’s coral reefs". Mar. Freshwater Res. 50: 839–66. doi:10.1071/MF99078. http://www.publish.csiro.au/?act=view_file&file_id=MF99078.pdf.
  3. ^ Jokiel 1978
  4. ^ a b "REEF ‘AT RISK IN CLIMATE CHANGE’". http://www.coralcoe.org.au/news_stories/climatechange.html. Retrieved 2007-07-12.
  5. ^ a b c Anthony, K. 2007; Berkelmans
  6. ^ Fitts 2001
  7. ^ a b Johnson, Johanna E; Marshall, Paul A (2007). Climate change and the Great Barrier Reef : a vulnerability assessment. Townsville, Qld.: Great Barrier Reef Marine Park Authority. ISBN 9781876945619. http://www.gbrmpa.gov.au/corp_site/info_services/publications/misc_pub/climate_change_vulnerability_assessment/climate_change_vulnerability_assessment.
  8. ^ Hoegh-Guldberg O, Mumby PJ, Hooten AJ, et al. (December 2007). "Coral reefs under rapid climate change and ocean acidification". Science 318 (5857): 1737–42. doi:10.1126/science.1152509. PMID 18079392. http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=18079392.
  9. ^ The Starving Ocean: Mass Coral Bleaching
  10. ^ Baird and Marshall 2002
  11. ^ Marshall, Paul; Schuttenberg, Heidi (2006). A Reef Manager’s Guide to Coral Bleaching. Townsville, Australia: Great Barrier Reef Marine Park Authority,. ISBN 1-876945-40-0. http://www.gbrmpa.gov.au/corp_site/info_services/publications/misc_pub/a_reef_managers_guide_to_coral_bleaching.
  12. ^ "NOAA Hotspots". http://coral.aoml.noaa.gov/pipermail/coral-list/2006-October/003757.html.
  13. ^ "Pro-opinion of NOAA Hotspots". http://www.osdpd.noaa.gov.
  14. ^ a b c Rosenberg E, Ben Haim Y (2002). "Microbial Diseases of Corals and Global Warming". Environ. Microbiol. 4 (6): 318–26. doi:10.1046/j.1462-2920.2002.00302.x. PMID 12071977.
  15. ^ Ryan Holl (17 April 2003). papers/Bioerosion.htm "Bioerosion: an essential, and often overlooked, aspect of reef ecology". Iowa State University. http://www.biology.iastate.edu/intop/1Australia/Australia papers/Bioerosion.htm. Retrieved 2006-11-02.
  16. ^ Kushmaro, A. (1996). "Bacterial infection and coral bleaching". Nature 380: 396. doi:10.1038/380396a0.
  17. ^ Sutherland KP, Porter J, Torres C (2004). "Disease and Immunity in Caribbean and Indo-pacific Zooxanthellate Corals". Marine Ecology Progress Series 266: 273–302. doi:10.3354/meps266273.
  18. ^ Reshef L, Koren O, Loya Y, Zilber-Rosenberg I, Rosenberg E (December 2006). "The coral probiotic hypothesis". Environ. Microbiol. 8 (12): 2068–73. doi:10.1111/j.1462-2920.2006.01148.x. PMID 17107548. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=1462-2912&date=2006&volume=8&issue=12&spage=2068.
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