Thünen (1783 - 1850), proposed a model to describe the change deforestation or crop wild areas, depending on the yield of the land, costs of production, market prices, freight costs and distance to market. Almost two centuries later, the market still has a considerable influence on the dynamics of land use. But the nineteenth century, when von Thunen proposed his model for the XXI century, "the market" has changed profoundly. It is much less near the town square and much more all international business transactions. Deforestation in the Amazon (see the case of Rondonia ) is explained more by linking producers to international markets for soybeans, which supply the need of the settlers. The replacement of forests for biofuel plantations in Mexico (see the case of Chiapas ), has more to do with the international market with the subsistence needs of communities in Chiapas. The market relations are much stronger than in the nineteenth century and can be more perverse.
however, may also have commercial relations virtuous. Such is the case of those who managed cork oak forests in the Mediterranean, as the providers of raw material for cork in the wine industry. International demand for cork stoppers, has kept alive the foresters of cork oak forests and the forests themselves, thus maintaining an important ecosystem in the Mediterranean.
The integration of forest landowners to markets, can have perverse effects, if there are no social or political mechanisms to avoid such effects and instead promote virtuous effects.
On 7 Last February, the journal Nature published the results of a very interesting study of Ruth S. DeFries, Thomas Rudel, Maria Uriarte and Matthew Hansen ( Deforestation Population Growth driven by urban and agricultural trade in the twenty-first century, Nature Geoscience 3, 178 to 181 (2010)) on the dynamics of deforestation in the world.
The authors used satellite images from 2000 to 2005 to estimate the loss of forests and jungles and made the correlation of these estimates with economic, agricultural and population in 41 countries in the humid tropics. Other similar studies in the past have tried to explain deforestation as a process driven by the growth of rural population that demands the opening of land for cultivation and promotes deforestation. Usually such studies, have low correlations.
Researchers in this new study found that between 2000 and 2005, forest loss is correlated significantly and positively associated with population growth urban and the increase in exports of agricultural products. In contrast, they found no correlation between rural population growth and loss of forest cover.
Results indicate that deforestation in the beginning of this century, is largely driven by demand for agricultural products by the urban domestic or foreign, through international trade.
There is a strong tendency of the population in the tropics to migrate to the cities. However, the data show that migration from rural to urban areas has not decreased but increased loss of forest cover. This unexpected result could be explained if we consider for example that the urban population consumes more meat, which requires more grass and more plantings of soybeans to feed livestock. It seems that, as far as satellite images show, the fact that a family migrated the countryside to the city, does not inhibit the expansion of ranching and the expansion of crops and agroforestry. The authors conclude
/ predict that policies to reduce deforestation in rural areas will not face the main cause of deforestation in the future. They recommend that efforts be concentrated on (1) reduce deforestation associated with agricultural production on an industrial scale, export-oriented and (2) increase yields in non-forest land to meet the demands of agricultural products without pressuring forest areas. -----------------
References
release about the study DeFries y colaboradores:
AFP: Urban growth, farm exports drive tropical deforestation
MongaBay: Forest conservation via REDD may be ineffective without addressing commodity consumption, trade
NASA Earth Observatory, World of Change: http://earthobservatory.nasa.gov/Features/WorldOfChange/deforestation.php
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