Chinese Arboriculture

Conservation efforts have increased China's tree cover.

Top: Tree cover across China in 2000, ranging from zero percent (light pink) to 90 percent (dark green). Bottom: Areas exhibiting a significant gain (blue) or loss (red) in tree cover between 2000 and 2010.

Vina et al., Science Advances 2016

Forests in China were diminishing in the late twentieth century, due to a combination of logging, floods, and conversion to farmland. In particular, devastating floods in 1998 contributed to massive soil erosion and prompted the government to devise a Natural Forest Conservation Program (NFCP), which banned logging in many natural forests and provided for improved monitoring to prevent illegal harvesting of trees. How effective was this intervention? 

Natural resource scientist Andrés Viña and colleagues at Michigan State University sought to assess the NFCP’s impact from 2000, when it was implemented, through 2010. They analyzed data primarily from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA’s Terra and Aqua spacecraft. MODIS scans the entire Earth every two days from poleto- pole orbits, detecting tree cover with a resolution of 250 meters per pixel. They supplemented those data with high resolution images of China from Google Earth. 

The researchers first determined that China’s tree cover increased significantly in 1.6% of its territory (157,315 square kilometers), though it also decreased in 0.38% of the country (37,268 square kilometers), during the first decade of the twenty-first century. They next created a mathematical model accounting for forest growth or decline due to a variety of factors, such as changes in industry and labor supply in various regions. Their statistical analyses credited NFCP with most of the forest expansion they observed.

However, Viña and his team note that China’s achievement must be evaluated in the context of forest health globally. Although logging has been reduced in China, it is expanding rapidly, both legally and illegally, in such places as Russia, Madagascar, Burma, Vietnam, and Indonesia. Much of that harvest is exported to China, where it replaces local production and is converted to products sold locally and exported worldwide.

The source of increased atmospheric greenhouse gases like carbon dioxide, as well as loss of biodiversity, may therefore simply have shifted from China to other countries. In order to address these challenges, the researchers call for an approach that considers tradeoffs among conservation, production, and consumption in importing and exporting countries alike. (Science Advances)