New Delhi, Nov 6 (UNI) Land degradation, driven by unsustainable use is one of the major challenges facing the world, especially poor countries, says the fourth Global Environment Outlook(GEO) Report.
Recent analyses using satellite data since 1981 indicate that the greatest areas of concern include tropical Africa, southeast Asia, south China, southeast Brazil and the Pampas, and the boreal forests in Alaska, Canada and eastern Siberia.
Demands on land resources and the risk to sustainability are likely to intensify, as population growth, economic development and urbanisation will drive demand for food, water, energy and raw material.
Land degradation, due to chemical contamination, is also widespread. A legacy of contaminated sites is common in old industrial heartlands in Europe. For example it is estimated that there many be more than 2 million such sites, of which 100 000 require remedy.
Soil erosion and depletion of soil nutrient are also posing major risk to agricultural land.
Soil erosion reduces on-site production where soil has been removed, and also results in off-site costs where deposited soil causes infrastructure damage and sedimentation in water bodies.
Moreover, depletion of soil nutrient is the most significant bio-physical factor limiting crop production over large areas in the tropics, particularly in sub-Saharan Africa.
The simple addition of manure or fertiliser may raise crop yield by as much as 16 times.
On the other hand, the high-level of nutrient application in industrialised countries cause eutrophication.
The intensity of land use for agricultural production has increased dramatically since 1987.
Regionally, cereal yields have increased by 2.5 per cent in Asia and Pacific, 37 per cent in West Asia, and 40 per cent in Latin America and the Caribbean.
Food produced per hectare has increased from a global average of 1.8 times in the 1980s to 2.5 tonnes today.
The main changes in land use at the global level since 1987 have been a loss of forest(On an average 73000 sq km annually), with concomitant increases in farmland, while lands formerly used as farmlands have been converted into urban areas.
Since 2006 and for the first time in history, more than half of the human population lives in cities.
The main causes of change in land use and use intensity have been increasing human population, changing consumption pattern, changes in technologies, policies and climate.
The area covered by forests in Europe and North America increased during the period under review, reversing the historical trend of temperate forest loss, but tropical deforestation, which began later than temperate deforestation, continues today.
The global average annual loss of primary forest was 50,000 km, while planted and semi-natural forest increased annually by 30 000 sq km on an average. Continued forest degradation remains a serious concern.
The GEO Report brought out by the UN has been prepared by about 390 experts.