The pie chart illustrates the main reason why agricultural land become less productive in the three regions of the world during 1990's.
It was evaluated that there were four causes of land degration. 35% of land is degraded because of Over-grazing. Deforestation is another cause for land degration which effects 30%of the land. 28% of worldwide land is degraded because of the Over-cultivation of land. The rest 7% of the pie belongs to other reasons.
On the other hand, in the second part of the chart it shows the causes of land degration by region. Out of the three regions surveyed, Deforestation and Over-cultivation had more impact on the loss of land productivity in Europe. Whereas, in Oceania Over-grazing was suffered the most.
To sum up, Europe had degraded most of its land while the impact of this on Oceania and North America was minimal.
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3. Detailed paras - Now describe the trends with all details :)