In some cases, cleared areas have been abandoned so that forests can naturally regenerate or they have been converted to plantations, and forests are returning to these areas. In Europe, for example, forest area has been increasing since 1950. Management practices such as fire suppression have helped create a more uniform forest cover in many temperate countries, with wooded landscapes dominated by single-age stands. The regenerated forests of temperate regions are often quite different from the original forests. Studies of the reforested areas of the northeastern United States show changes in tree species composition and smaller tree sizes compared with those of the historical forest cover.
Forest health is also an issue in Europe.
A 1994 assessment of forests in 29 countries found that 26.4 percent of the trees surveyed suffered from moderate to severe defoliation. This continues a trend that has been observed through annual assessments since 1986. The FAO Synthesis report includes new estimates on how forest cover is changing within the tropics. The latter represent the most common degradation pattern, accounting for about one quarter of all forest cover changes. The FAO imagery study also sheds some light on the underlying causes of forest conversion and degradation in different tropical regions of the world.