Land Cover Change and Deforestation
The conversion of natural lands to croplands, pastures, urban areas and other anthropogenic landscapes represents the most visible form of human impact on the environment.
Today, roughly 40% of Earth’s land surface is under agriculture, and 85% has some level of anthropogenic influence. Although the world’s population is now 50% urban, urban areas occupy less than three percent of Earth’s surface.
We can conclude from this that large-scale land-cover change is largely a rural phenomenon (Berkes and Folkes, 1998).
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As regards the demographic and development transitions, the world remains divided in various stages of the land-use transition.
The developed nations are urbanized and have economies dominated by service and technology industries while the developing nations continue to experience rapid population growth, remain largely rural, and have labour forces concentrated in the primary sector (agriculture and mining industries).
Today, most land conversion from natural states to human uses is occurring in the developing world, particularly in the tropics through forest conversion to agricultural lands.
One exception is the Russian Far East, which is one of the few developed world regions with high rates of primary forest deforestation mostly for logging and not for agricultural lands.
Demographic variables are linked at different scales to this phenomenon. However, there is disagreement on the impact of population versus other factors, with some studies suggesting that demographic dynamics contribute more than any other process to deforestation while others suggesting the superiority of economic factors.
Geist & Lambin (2003), meta-analysis of 152 case studies of tropical deforestation suggests that, although most cases of deforestation are driven at least partially by population growth, population factors almost always operate in connection with political, economic, and ecological processes and the relative impact of each factor varies.
In much of the developing world fertility rates are at the increase especially in the villages but declined so rapidly as in urban areas.
The regions of highest fertility also coincide with the most remotely settled lands where the agricultural frontier continues to advance, areas that are both biodiverse and ecologically fragile.
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This high fertility and associated rapid population growth directly contributes to land conversion in these forested areas. In such regions, children constitute an asset to farm families that are often short of labour. Positive correlations between fertility and deforestation have been found in studies in Central and South America.
The settlement life cycle of farm homesteads also helps to explain when and where forest clearing will occur. Immediately following settlement, deforestation is high as land is cleared for subsistence crops.
An increase scale in deforestation may occur as farms move from subsistence to market-oriented crops or expand into livestock rearing.
