The Proceedings of the National Academy of Sciences has published a look at changes in area and density of forests around the world. The figure above shows that quite a few nations have seen rising forest volume. Volume would be area times density, and the red line marks the line of no change in volume. You can see that quite a few nations, including some developing nations, lie above that line, indicating that the forests are increasing in since.
The other interesting finding is the relationship between gross domestic product (a measure of national economic activity) and change in forest size. When GDP per capita was above $4,600/person, the forest size grew (except for Canada, which reported no change in area or density). Below $4,600/person, some nations experienced large losses, others experienced increases as large as those of wealthier nations.
The nations with increasing volume or area of forests had generally gone through a societal transition. The authors describe this transition by saying that:
combinations of factors were responsible, including agricultural and wider socioeconomic factors as well as increasingly effective enforcement of forest laws. Growth in off-land employment and migration to urban areas reduced pressures on the forest by rural populations. Rising crop yield has spared and may well continue to spare land for forests (29). Rising timber yield, for example, in plantations helps meet timber demand with fewer disturbances to natural forests
This meshes nicely with the basic scenario I put forward at Seedmagazine.com last month: that development is the best defense of forests. Countries with solid governments that can protect forests and with educated populations that can take advantage of new technologies are more likely to wind up protecting existing forests and increasing the forested land.
Author Jesse Ausubel of Rockefeller University in New York told the Times that when he began studying global forests, “he personally had expected to live in a ‘skinhead’ earth by 2050.” He doesn’t any more.
The details obviously matter, and an increase in area of plantations wouldn’t balance a decline in native old-growth forests in terms of preserving biodiversity and other ecosystem services. There’s no measure here of forest quality in any meaningful sense, though rising forest area is unquestionably a positive sign.
While we’re on the tree theme, check out Science Creative Quarterly’s article on paintings made by trees.