Shifting agriculture was greatest in Asia about 30 per cent but only about 15 per cent over the whole tropical world. It appears that the proportion of direct conversion of forest to agriculture is increasing and the proportion of shifting agriculture is decreasing with time.
The fact that plantations remove the timber pressure on natural forests does not translate eventually into less, but rather into more deforestation. Indeed, it is feared that agricultural expansion which is the main cause of deforestation in the tropics might replace forestry in the remaining natural forests Anon. The impact of timber plantations could thus turn out to be quite detrimental to tropical forest ecosystems Kartodihardjo and Supriono, Tree crops and rubber in particular plays a more important role in deforestation in Indonesia than subsistence-oriented shifting cultivation Chomitz and Griffiths, Unfortunately about one-half of the plantations in the tropics are established on native forest cleared for the purpose.
Moreover plantations can promote deforestation by constructing roads that improve access of the shifting cultivators and others to the forest frontier. However, logging can seriously degrade forests Putz et al. Logging in Southeast Asia is more intensive and can be quite destructive. However, logging provides access roads to follow-on settlers and log scales can help finance the cost of clearing remaining trees and preparing land for planting of crops or pasture.
Logging thus catalyzes deforestation Chomitz et al. Fuelwood gathering is often concentrated in tropical dry forests and degraded forest areas Repetto, ; ; Rowe et al. Fuelwood is not usually the major cause of deforestation in the humid tropics although it can be in some populated regions with reduced forest area such as in the Philippines, Thailand and parts of Central America.
Fuelwood gathering was considered to be the main cause of deforestation and forest degradation in El Salvador Repetto, In the drier areas of tropics, Fuelwood gathering can be a major cause of deforestation and degradation. Stripping trees to provide fodder for grazing animals can also be a problem in some dry areas of the tropics but is probably not a major cause of deforestation. Clear cutting and overgrazing have turned large areas of Qinghai province in China into a desert.
Overgrazing are causing large areas of grasslands north of Beijing and in Inner Mongolia and Qinghai province to turn into a desert. One man who lived in a village on the eastern edge of the Qinghai-Tibet plateau that was being swallowed up by sand told the New York Times, "The pasture here used to be so green and rich. But now the grass is disappearing and the sand is coming.
In Xillinggol Prefecture in Inner Mongolia, for example, the livestock population increased from 2 million in to 18 million in , turning one third of the grassland area to desert. Unless something is done the entire prefecture could be uninhabitable by Overgrazing is exacerbated by sociological phenomena called "the tragedy of the common.
This leads to more animals than the land can support. Grassland in Qinghai that can support 3. Animals remove the vegetation and winds finished the job by blowing away the top soil, transforming grasslands into desert. Fire is a good servant but has a poor master. Fire used responsibly can be a valuable tool in agricultural and forest management but if abused it can be a significant cause of deforestation Repetto, ; Rowe et al.
Based on the data available from countries representing 65 per cent of the global forest area, an average of Deforestation due to road pavements in Brazil had also lead to higher incidences of forest fires Carvalho et al. The area of land involved is quite small and it is not seen as a major cause of primary deforestation.
Mining is a lucrative activity promoting development booms which may attract population growth with consequent deforestation. The deforestation rate due to mining activities in Guyana from to increased 2. Massive and unchecked mining of coal, iron ore and bauxite in Jharkhand, India has caused large scale deforestation and created a huge water scarcity Anon.
Moreover, Roads constructed to support the mining operations will open up the area to shifting agriculturists, permanent farmers, ranchers, land speculators and infrastructure developers.
The construction of roads, railways, bridges, and airports opens up the land to development and brings increasing numbers of peoples to the forest frontier. If wood is used as fuel in mining operations and it is sources from plantations established for the purpose, it can cause serious deforestation in the region.
On the other hand, mining can be labour intensive and take labour away from clearing forest. Tropical forests are a major target of infra-structure developments for oil exploitation, logging concessions or hydropower dam construction which inevitably conveys the expansion of the road network and the construction of roads in pristine areas Kaimowitz and Angelsen, The construction of roads, railways, bridges, and airports opens up the land to development and brings increasing numbers of people to the forest frontier.
Wilkie et al. The development of these infra- structure projects are of worldwide concern, since tropical forest clearing accounts for roughly 20 per cent of anthropogenic carbon emissions destroying globally significant carbon sinks Anon.
In , eight per cent of all West German trees exhibited damage that rose to about 52 per cent by Raloff, and half of the trees reported dying of Waldsterben in the Alps Lean, High elevation forests show the earliest damage including forests in the north-east and central United States.
More recently, linkages have been documented between the civil war in Myanmar and the timber trade between Myanmar and Thailand. Myanmar regime sells timber to the Thais to finance its civil war against the Karen hill tribe. Forest destruction in El Salvador has resulted from war. Apart from military involvements in wars, the role of military in deforestation has been documented in Southeast Asia and South America Mather, ; Sands, The authors also observed that role of powerful military in Brazilian politics are a major cause of Amazonian forest destruction.
Unfortunately, the national governments of tropical and sub-tropical countries adopt tourism for easy way of making money sacrificing the stringent management strategies. Further, many companies and resorts who advertise themselves as eco-tourist establishments are in fact exploiting the forests for profit.
In Cape Tribulation, Australia, for example, the rain forest is being threatened by excessive tourism Colchester and Lohmann, Similarly, in the Terai Duars of eastern India foothill Himalaya, eco-tourism is encouraged and we fear this is being done without developing adequate management plans.
For instance, the Chilapatta Reserve Forest in this area is opened for eco-tourism for its ancient ruins deep in the forest and a tree species Myristica longifolia that exudes a blood like sap when injured. The site has become a popular eco-tourist destination because of the ruins and for this blood exuding tree. In the whole forest only eight individuals were found but two of the trees in the near vicinity of the ruins completely dried away due to repeated injuries caused to the plants by the curious tourists Shukla, In fact, in the name of eco-tourism, infra-structure development is taking place mostly be the private players in these wilderness areas which are further detrimental in terms of attracting peoples other than tourists also, causing deforestation especially deep in the forest.
Deforestation: Causes, Effects and Control Strategies 11 3. It is in the name of development that irrational and unscrupulous logging, cash crops, cattle ranching, large dams, colonisation schemes, the dispossession of peasants and indigenous peoples and promotion of tourism is carried out. It is the throw away culture of the industrialized countries now advertised in and forced on to the Third World countries that is leading to the throwing away of the world.
Such a development leads to overconsumption which is the basic underlying cause of deforestation. Colonialism turned previously self-sufficient economies into zones of agriculture export production.
This process continues even today in different form of exploitation and the situation is worsening Colchester and Lohmann, Unfortunately also the governments of these poor resource rich countries had generally adopted the same growth-syndrome as their western neighbours or their erstwhile colonial master giving emphasis on maximizing exports, revenues and exploiting their rich natural resources unsustainably for short-term gains. Moreover, corruption in government, the military and economic powers is well known.
The problem is further worsened by the low price of the most Third World exports being realized in the international market Colchester and Lohmann, For instance, construction of roads for logging operations in some South-east Asian countries was funded by Japanese aid which allowed the Japanese timber companies to exploit the forests of these countries.
Understandably, these timber companies profitably exploited the forests while the South-east Asian countries were left owing Japan money for construction of their roads Colchester and Lohmann, The impact of population density on deforestation has been a subject of controversy.
Poverty and overpopulation are believed to be the main causes of forest loss according to the international agencies such as FAO and intergovernmental bodies. It is generally believed by these organizations that they can solve the problem by encouraging development and trying to reduce population growth.
Conversely, the World Rainforest Movement and many other NGOs hold unrestrained development and the excessive consumption habits of rich industrialized countries directly responsible for most forest loss.
However there is good evidence that rapid population growth is a major indirect and over-arching cause of deforestation. More people require more food and space which requires more land for agriculture and habitation. This in turn results in more clearing of forests.
Arguably increasing population is the biggest challenge of all to achieve sustainable management of human life support systems and controlling population growth is perhaps the best single thing that can be done to promote sustainability. Overpopulation is not a problem exclusive to Third World countries.
The growing population in rich industrialized nations are therefore responsible for much of the exploitation of the earth and there is a clear link between the overconsumption in rich countries and deforestation in the tropics Colchester and Lohmann, Poverty and overpopulation are inextricably linked.
Poverty, while undeniably responsible for much of the damage to rainforests, has to a large extent been brought about by the greed of the rich industrialized nations and the Third World elites who seek to emulate them. Development is often regarded as the solution to world poverty, seldom helps those whose need is greatest.
Thus, it is often the cause rather than the cure for poverty. The claim that overpopulation is the cause of deforestation is used by many governments and aid agencies as an excuse for inaction. In tropical countries, pressure from human settlement comes about more from inequitable land distribution than from population pressure. Generally, most of the land is owned by small but powerful elite which displaces poor farmers into rainforest areas.
So long as these elites maintain their grip on power, lasting land reform will be difficult to achieve Colchester and Lohmann, and deforestation continues unabated. Therefore poverty is well considered to be an important underlying cause of forest conversion by small-scale farmers and naturally forest-dense areas are frequently associated with high levels of poverty Chomitz et al.
The population also often lacks the finance necessary for investments to maintain the quality of soil or increase yields on the existing cleared land Purnamasari, Deforestation is affected mainly by the uneven distribution of wealth.
Shifting cultivators at the forest frontier are among the poorest and most marginalized sections of the population. Consequently they have no option but to clear the virgin forest. Deforestation including clearing for agricultural activities is often the only option available for the livelihoods of farmers living in forested areas Angelsen, Moreover, governments and international aid agencies earlier believed that by encouraging colonisation and transmigration schemes into rainforest areas could alleviate poverty of the areas in the financially poorer countries.
Such schemes have miserably failed but hurted the indigenous people and the environment. In Indonesia, the Transmigrasi Program of had caused annual deforestation of two lakh hectares Colchester and Lohmann, Dispossessed and landless people bring increased population pressure to the forest frontier.
Further, new migrants in the area increase demand for food and other agricultural products which can induce the farmers at the forest frontier to increase their agricultural production by expanding agricultural land by clearing the forests Levang, Moreover, the new migrants may not care for conservation of the forests in their new home which further accelerates deforestation of the area. This means they have to clear more forest to survive. Poorly defined tenure is generally bad for people and forests Chomitz et al.
In many countries government have nominal control of forests but are too weak to effectively regulate their use. This can lead to a tragedy of the commons where forest resources are degraded. In frontier areas deforestation is a common practice and legalized way of declaring claim to land and securing tenure Schneider, One point of view is that development will increase land productivity and thereby reduce the need to clear forests to meet food requirements. Another is that development will produce further capital and incentive to expand and clear more forest.
The former may be the case when constrained by a fixed food demand. The latter may be the case when food demand may not be satisfied owing to a continuing export market and rising internal population with rising levels of consumption. Profits from deforestation vary from less than a dollar to thousand dollars per hectare depending on location, technologies and land use systems Chomitz et al.
Conversely, through transfers, stronger credit markets and better opportunities for off-season employment can increase income as well as deforestation by small land holders.
Higher prices for crops and lower prices for farm inputs also spur faster deforestation Chomitz et al. Wage increase can also stimulate deforestation Barbier and Cox, Technological innovations make farming more profitable either prompting the expansion of farms into forest or attract new farmers to forest frontiers Angelsen and Kaimowitz, ; Angelsen, Even when the increase in commodity price is only temporary, it tends to raise expectation about future prices, increasing the expected probability from land clearance and conversion to agriculture Angelsen, ; Sunderlin et al.
Many development policies have failed because they have supported either wittingly or unwittingly the development of those who already have land, power, influence and political clout. This further alienates the rural poor and puts the pressure back on the forests. Poor farm households or commercial loggers have little incentive to care about the environmental effects of their actions.
Such unaccounted costs give rise to economic failures such as local market failures, policy failures and global appropriation failures Panayotou, Market fails due to unregulated market economy which does not produce an optimal outcome.
Prices generated by such market does not reflect the true social costs and benefits from resource use and convey misleading information about resource scarcity, providing inadequate incentives for management, efficient utilization and enhancement of natural resources.
Policy failures or market distortions are result of misguided intervention or unsuccessful attempts to mitigate failures resulting in worse outcomes Panayotou, For instance, lack of respect of traditional land rights make property rights to forest land uncertain and could encourage short-term exploitation of forests rather than long-term sustainable use.
Further, global appropriation failures occur as in the case of tropical forests- the benefits of biodiversity conservation and the value of the genetic pool in developing new medicines, crops and pest control agents are poorly reflected in market allocations.
For instance, it was argued that improved terms of trade for agricultural and forest product exports and higher real exchange rates make it more profitable to convert forests to other uses Capistrano, ; Southgate, ; Kant and Redantz, The initial empirical analysis done by Scrieciu appears to confirm that tropical deforestation is caused by the drive for maximizing profits within the agricultural sector.
Rampant consumerism by the developed countries frequently has been claimed as a major reason for tropical deforestation. The opening of tropical countries to the world commodity markets accelerated deforestation. The products include coffee, sugar, bananas, cotton and beef in Central America and oil palm, rubber and timber in Southeast Asia. The extraction of non-wood forest products has been suggested as a way to add value to the forest but it is not economical when compared to clearing options.
If some means could be devised where those who benefit from the environmental values could pay the forest owners or agents of deforestation for them, then the option to not clear would become more competitive. Alternatively, if the national governments value the environmental benefits, it could apply a tax or disincentives to clear.
However, even though maintenance of the environmental services is essential for sustained economic development, deforesting nations usually have more immediate goals and are unprepared to take this step. Deforestation: Causes, Effects and Control Strategies 15 3. Illegal forest practices may include the approval of illegal contracts with private enterprises by forestry officers, illegal sale of harvesting permits, under-declaring volumes cut in public forest, under- pricing of wood in concessions, harvesting of protected trees by commercial corporations, smuggling of forest products across borders and allowing illegal logging, processing forest raw materials without a license Contreras-Hermosilla, ; Effects of deforestation 4.
Deforestation can change the global change of energy not only through the micrometeorological processes but also by increasing the concentration of carbon dioxide in the atmosphere Pinker, because carbon dioxide absorbs thermal infrared radiation in the atmosphere. Moreover deforestation can lead to increase in the albedo of the land surface and hence affects the radiation budget of the region Charney, ; Rowntree, ; Gupta et al.
Deforestation affects wind flows, water vapour flows and absorption of solar energy thus clearly influencing local and global climate Chomitz et al. Deforestation on lowland plains moves cloud formation and rainfall to higher elevations Lawton et al.
Deforestation disrupts normal weather patterns creating hotter and drier weather thus increasing drought and desertification, crop failures, melting of the polar ice caps, coastal flooding and displacement of major vegetation regimes. In the dry forest zones, land degradation has become an increasingly serious problem resulting in extreme cases in desertification Dregne, Desertification is the consequence of extremes in climatic variation and unsustainable land use practices including overcutting of forest cover Anon.
Global warming or global change includes anthropogenically produced climatic and ecological problems such as recent apparent climatic temperature shifts and precipitation regimes in some areas, sea level rise, stratospheric ozone depletion, atmospheric pollution and forest decline.
Tropical forests are shrinking at a rate of about five per cent per decade as forests are logged and cleared to supply local, regional, national and global markets for wood products, cattle, agricultural produce and biofuels Anon. One of the most important ramifications of deforestation is its effect on the global atmosphere. Deforestation contributes to global warming which occurs from increased atmospheric concentrations of greenhouse gases GHG leading to net increase in the global mean temperature as the forests are primary terrestrial sink of carbon.
Thus deforestation disrupts the global carbon cycle increasing the concentration of atmospheric carbon dioxide. Tropical deforestation is responsible for the emission of roughly two billion tonnes of carbon as CO2 to the atmosphere per year Houghton, Release of the carbon dioxide due to global deforestation is equivalent to an estimated 25 per cent of emissions from combustion of fossil fuels Asdrasko, With removal of part of the forest, the area cannot hold as much water creating a drier climate.
Urban water protection is potentially one of the most important services that forest provides Chomitz et al. Filtering and treating water is expensive. Forests can reduce the costs of doing so either actively by filtering runoff or passively by substituting for housing or farms that generate runoff Dudley and Stolton, Deforestation can also result into watersheds that are no longer able to sustain and regulate water flows from rivers and streams.
Once they are gone, too much water can result into downstream flooding, many of which have caused disasters in many parts of the world. This downstream flow causes soil erosion thus also silting of water courses, lakes and dams. Deforestation increases flooding mainly for two reasons. Second, deforestation often results in soil compaction unable to absorb rain. Locally, this causes a faster response of stream flows to rainfall and thus potential flash flooding Chomitz et al.
Moreover deforestation also decrease dry season flows. The long term effect of deforestation on the soil resource can be severe. Clearing the vegetative cover for slash and burn farming exposes the soil to the intensity of the tropical sun and torrential rains. Forest floors with their leaf litter and porous soils easily accommodate intense rainfall.
The effects of deforestation on water availability, flash floods and dry season flows depend on what happens to these countervailing influences of infiltration and evapotranspiration- the sponge versus the fountain Bruijnzeel, Deforestation and other land use changes have increased the proportion of the basin subject to erosion and so over the long run have contributed to siltation. Heavy siltation has raised the river bed increasing the risk of flooding especially in Yangtze river basin in China, the major river basins of humid tropics in East Asia and the Amazonian basin Yin and Li, ; Bruijnzeel, ; Aylward, , Bruijnzeel et al.
Retaining the biodiversity of the forested areas is like retaining a form of capital, until more research can establish the relative importance of various plants and animal species Anon. The biodiversity loss and associated large changes in forest cover could trigger abrupt, irreversible and harmful changes. These include regional climate change including feedback effects that could theoretically shift rainforests to savannas and the emergence of new pathogens as the growing trade in bushmeat increases contact between humans and animals Anon.
Elephant habitat located at northern West Bengal in India is part of the Eastern Himalaya Biodiversity Hotspot which is characterized by a high degree of fragmentation. The heavy fragmentation of this habitat has resulted into an intense human-elephant conflict causing not only in loss of agricultural crops but also human and elephant lives.
Mortality of about 50 persons and 20 elephants was reported due to these severe human-elephant conflicts from this hotspot area annually Sukumar et al.
By destroying the forests, all potential future revenues and future employment that could be derived from their sustainable management for timber and non- timber products disappear.
The social consequences of deforestation are many, often with devastating long-term impacts. The intrusion of outsiders destroys traditional life styles, customs and religious beliefs which intensifies with infra-structure development like construction of roads which results into frontier expansion often with social and land conflicts Schmink and Wood, The most immediate social impact of deforestation occurs at the local level with the loss of ecological services provided by the forests.
By destroying the forests we risk our own quality of life, gamble with the stability of climate and local weather, threaten the existence of other species and undermine the valuable services provided by biological diversity. Stretegies to reduce deforestation Ways to reducing deforestation must go hand in hand with improving the welfare of cultivators at the forest frontier. Any policy that does without the other is unacceptable. There are no general solutions and strategies since these will vary with region and will change over time.
All strategies require cooperation and goodwill. Effective implementation is essential including stakeholder participation, development of management plans, monitoring and enforcement. The strategies should be such that on one hand they should recognize the critical roles of national, state and municipal governments and on other hand empower the civil society and the private sector to take a pro-active role in reducing deforestation, often working in conjunction with government.
Consequent of reduced population, increase in per capita income will occur as a consequence of increased incomes and literacy rates which will reduce pressure on the remaining forests for new human settlement and land use change. Significant work is underway on tools for use in monitoring developing country adherence to their agreed REDDS targets Chomitz et al.
Protected areas alone, however, are not sufficient to conserve biodiversity. They should be considered alongside, and as part of, a wider strategy to conserve biodiversity. The minimum area of forest to be protected is generally considered to be 10 per cent of total forest area. It is reported that Tropical and temperate forests have the highest proportions of their forests in protected areas and boreal forests have the least. The Americas have the greatest proportion while Europe the least proportion of protected areas Anon.
If the forest does not have a dedicated long-term tenure for timber production then there is no incentive to care for the long-term interests of the forest. FAO found that 89 per cent of forests in industrialized countries were under some form of management but only about six per cent were in developing countries. If 20 per cent could be set aside, not only could timber demand be sustainably met but buffer zones could be established to consolidate the protected areas.
This would form a conservation estate that would be one of the largest and most important in the world Anon. Governments can impose realistic prices on stumpage and forest rent and can invest in improving the sustainable productivity of the forest. National and international beneficiaries of the environmental services of forests have to pay for such services Chomitz et al.
This success can further be more realized by integrating participatory mode of management with these collection schemes to ensure rights and tenure with equity in resource and benefit sharing for improving the livelihood of the rural poors who actually are the primary stakeholders of conservation and management.
Achieving ecological sustainability means that the ecological values of the forest must not be degraded and if possible they should be improved. This means that silviculture and management should not reduce biodiversity, soil erosion should be controlled, soil fertility should not be lost, water quality on and off site should be maintained and that forest health and vitality should be safeguarded. Rice Annotation Project. Nucleic Acids Res.
Sato, Y. Field transcriptome revealed critical developmental and physiological transitions involved in the expression of growth potential in japonica rice.
BMC Plant Biol. Hirano, K. Miyashita, Y. Identification and expression analysis of PIN genes in rice. Plant Sci. Takai, T. Canopy temperature on clear and cloudy days can be used to estimate varietal differences in stomatal conductance in rice. Hirayama, M. Drought resistance. Cabuslay, G. Physiological evaluation of responses of rice Oryza sativa L.
Kato, Y. Identification of QTLs controlling rice drought tolerance at seedling stage in hydroponic culture. Euphytica , — Download references. We thank K. We thank N. Hattori, T. Tanaka, M. Yamanouchi, K. Matsubara, S. Mochizuki, N. Yokotani, T. Mizubayashi, T. Ando, N.
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