全球农业土地退化Global agricultural land degradation

The pie chart illustrates the main causes of the deterioration of global farmland and the table gives data regarding the influence of these causes on three areas during the 1990s. Overall, overgrazing was the leading cause of global land degradation and Europe had the highest proportion of degraded land. With regard to global land degradation, the leading cause was overgrazing at 35%. This was closely followed by cutting down forests and growing too many crops, which accounted for 30% and 28%, respectively. Other reasons were only responsible for 7% of the damage. Turning to the individual areas, Europe had the highest proportion of land that was less fertile at 23%. The main cause was deforestation at 9.8% and the least was overgrazing at 5.5%. Oceania had 13% of its land that was degraded and this was caused by overgrazing at 11.3% and deforestation at a much lower 1.7%. There was no damage due to over-cultivation in Oceania. North America had the lowest proportion of arable land damaged at 5%. The biggest cause was over-cultivation at 3.3% and the least was the removal of forests at 0.2%.