Soil and Water Conservation College, Beijing Forestry University, Haidian District, People's Republic of China.
Ambio. 2010 Jun;39(4):279-83. doi: 10.1007/s13280-010-0038-z.
Traditional approaches to ecosystem restoration have considered afforestation to be an important tool. To alleviate land degradation in China, the Chinese government has therefore invested huge amounts of money in planting trees. However, the results of more than half a century of large-scale afforestation in arid and semi-arid China have shown that when the trees are not adapted to the local environment, the policy does not improve the environment, and may instead increase environmental degradation. When precipitation is lower than potential evaporation, surface soil moisture typically cannot sustain forest vegetation, and shrubs or steppe species replace the forest to form a sustainable natural ecosystem that exists in a stable equilibrium with the available water supply. The climate of much of northwestern China appears to be unsuitable for afforestation owing to the extremely low rainfall. Although some small-scale or short-term afforestation efforts have succeeded in this region, many of the resulting forests have died or degraded over longer periods, so policymakers must understand that these small-scale or short-term results do not support an inflexible policy of large-scale afforestation throughout arid and semi-arid northwestern China. Rather than focusing solely on afforestation, it would be more effective to attempt to recreate natural ecosystems that are better adapted to local environments and that thus provide a better chance of sustainable, long-term rehabilitation.
传统的生态系统恢复方法认为造林是一种重要的手段。为了缓解中国的土地退化问题，中国政府因此投入了大量资金进行植树造林。然而，半个多世纪以来在中国干旱和半干旱地区进行的大规模造林的结果表明，当树木不适应当地环境时，该政策并不会改善环境，反而可能会加剧环境恶化。当降雨量低于潜在蒸发量时，地表土壤水分通常无法维持森林植被，而灌木或草原物种会取代森林，形成一个与可用水资源稳定平衡的可持续自然生态系统。由于降雨量极低，中国西北部大部分地区的气候似乎不适合造林。尽管该地区的一些小规模或短期的造林工作取得了成功，但许多造林后的森林在较长时间内已经死亡或退化，因此政策制定者必须认识到，这些小规模或短期的结果并不能支持在干旱和半干旱的中国西北地区大规模进行造林的僵化政策。与其单纯地关注造林，尝试重建更能适应当地环境的自然生态系统，从而为可持续的长期恢复提供更好的机会，可能会更为有效。
