题目：The pie chart below shows the main reasons why agricultural land becomes less productive. The table shows how these causes affected three regions of the world during the 1990s.
The information given by the pie chart and the table is about the main reasons for worldwide land degradation and how three areas of the world were affected by the reasons over the 1990s.
The given causes affected different regions differently in the 1990s. Specifically, in Europe which had the largest proportion of land degradation (23%), 9.8% land degraded was due to deforestation. However, it only took up 0.2% in North America and 1.7% in Oceania. As for Oceania with 13% of total land degradation, the most serious cause was over-grazing (11.3%). Interestingly, there was no link between its land degradation and over-cultivation which made 3.3% land degraded in North America whose total land degraded accounted for 5%.
All in all, it is clear to see that over-grazing and deforestation are the most important reasons for land degradation, and the reasons mentioned above played different roles in different regions during the 1990s.