The charts illustrate the main causes of decreased agricultural land productivity and show how these factors affected three following regions: North America, Europe, Oceania in the 1990s.
Overall, the primary reason for worldwide land degradation was over-grazing, followed by deforestation and over-cultivation. In term of regional impact, Europe experienced the highest land degradation, whereas North America had the last.
Agricultural land less-productivity caused by three main reasons that were approximately equal. They were over-grazing (35%), deforestation (30%), over-cultivation (28%). Other causes were only 7%. In Europe, deforestation was the leading cause of land degradation, accounting for 9.8%, which was the largest amount among three regions. With regard to over-cultivation, the data show that this reason of less-productivity also spread in Europe, while European agriculture declining was in second place by over-grazing with 5.5%. Totally 23% of European land degraded because of these causes.
The loss of forested areas also affected North American agriculture; however, it accounted for the lowest proportion among all causes of degradation in this region. Over-cultivation was the major factor contributing to decreased land productivity, being 3.3%, which was more than twice the level of over-grazing (1.5%). Total quantity was 5%. The total amount of agricultural land degradation in North America was lower than in Oceania, where over-cultivation was not a contributing factor. Oceanian agriculture’s degradation by deforestation was 1.7% and over-grazing 11.3%.