Soil Degradation in Relation to Deforestation, Overgrazing and Arable Agriculture

Soil degradation in relation to deforestation, overgrazing and arable agriculture

1. Recent situation

As an essential component of ecosystems, soil plays a vital role in crucial life-supporting composition and process. Human welfare depends heavily on the soil resource to produce the bulk of our food, and provide the cornerstone of human civilization. Yet we continue to damage soil in many different ways.

Soil degradation can be defined as a natural or human-induced process which impairs current or future capacity of the land to produce goods or services. There is replacement of primary plant communities by secondary communities, which favours the population growth of human being but alters the soil formation. In other point of view, Johnson (1997) regards soil degradation is change or disturbance to the soil perceived to be deleterious or undesirable. In many places, soil has been damaged at a rate faster than its natural regenerate capacity, denoting an unsustainable use of the renewable resource. On average, it takes the nature 10 to 40 thousand years to form a soil layer of one meter thick. Ironically, humans only need to take a short while to destroy it.

2.1 World situation on deforestation

Up to 2011, about half of the world’s original jungles had been destroyed and most of them are ruined within the recent half century. From 1990, nearly half of the tropical forests have been damaged all over the world. More than half of soils that have been degraded by deforestation are located in Asia while 15% are in South America. It is indicated that deforestation is the main cause of soil degradation in South America (41%), in Asia (40%) and also in Europe (38%), particularly in Central and Oriental European countries (The Nature conservancy, 2011).

2.2 Cause of deforestation

Due to the alarming population growth, there is a huge demand on the resources and land. Hence, people fall short on logging to squeeze more timber and space. Forests are then cut down to be consumed or sold to developed countries as fuel or timber. Meanwhile, the natural vegetation is removed for a non-forest use, for example, land is cleared for cultivation, road construction, livestock pasture, large-scale commercial forestry and urbanization. One of the most severely damaged rainforest is Amazon. Many developed countries are highly depends on the export of the coffee bean, rubbers, beef and many other food products. The total area of forest lost in the Amazon rose from 415,000 to 587,000 square kilometres in the nineties, with most of the lost forest becoming pasture for cattle. The mean annual deforestation rate from 2000 to 2005 was 18% higher than in the previous five years from 22,392 km2 to 19,018 km2 (Barreto et al. 2006). Moreover, deforestation was quite often to be used in