Deforestación México

DEFORESTATION IN MEXICO

Definitions

It is very important to consider the definitions we use as each definition will be a different assessment. One of the definitions used on deforestation is agreed by the United Nations for Food and Agriculture Organization (FAO). Deforestation is "the conversion of forests to other land use or long-term reduction in forest cover below 10%." This definitionimplies that the loss must be permanent and that the site has changed to other use (agriculture, grazing, dams, or urban areas) (FRA 2005).

This definition explicitly excludes areas where trees are removed or the forest has been damaged but has declined to less than 10% of its original or has not been permanently replaced by another activity.

Therefore when we talk about deforestation, weare not talking about the deterioration of forests. Only those areas totally or almost totally lost their forest cover. If a forest loses 80% of its forest cover is not considered deforestation. So it is better to speak of deforestation and degradation or deterioration. The degradation includes changes within the forest that negatively affect the structure or function of the forest or site reducingtheir ability to provide products or services (FRA 2005).

The degradation involves the removal of trees without having to reach less than 10% of the original canopy cover and also includes changes that are not detected by remote sensing (aerial photographs or satellite images), as the removal of timber in ground clearance for firewood and other forest components such as mosses, epiphytes,palms, fungi and wildlife.

How much forest we lost annually?

This question really should be broader. How many natural ecosystems we lose annually? Since we have not only forests in our country but we have a great diversity of ecosystems such as grasslands, shrub lands, coral reefs, mangroves, etc. (Frame 1). For example, the Sonora Desert contains the famous known as giant saguaro cactus. Thiscactus up to 10 meters in height can live to 200 years. However, the transformation of these arid ecosystems is not covered by the measures of deforestation.

All countries have lost or are losing natural ecosystems. Some countries such as Madagascar and the Philippines currently contain less than 10% of their original ecosystems. The loss of these ecosystems means an impoverishment from manypoints of view. Lose economic alternatives (wood products, non-wood products, wildlife), we lose properties and environmental services (soil retention, oxygen production, carbon fixation, maintenance of the water cycle, etc.). With very costly consequences such as floods and landslides.

Although there is clearly a steady loss of our natural ecosystem, unfortunately not so easy to determine howmuch we are losing. Since the 1970's, when satellites began to send images of the earth, began the systematic evaluation of changes in the coverage of natural ecosystems.

How much have you lost Mexico?

Since late 1970, began to publish estimates of deforestation in Mexico. The range of estimates of deforestation is very broad and ranges from 75 000 to almost two million hectares per year (Lundet al. 2002). FAO estimates from the 80s have been quite consistent with a range between 350 and 650 thousand hectares per year.

Recent analysis estimated that Mexico lost 29.765 km2 of forest (an area the state of Guanajuato) from 1976 to 1993, while from 1993 to 2000 was lost 54.306 km2 (area equivalent to the state of Campeche). The deforestation rate increased from first to second period,from 175 000 hectares to 319 hectares annually (Velasquez et al. 2002).

FAO documented deforestation of 314 hectares annually from 2000 to 2005. While this is taken as good news, there are several problems with this estimate.

1. Conversion to agriculture and livestock. The progress of agricultural land and livestock replaces forests. The most obvious case in Mexico is the conversion of...