蒋高明指出，单一种植的杨树丛林容易加工成杨树板材，销售过程中利润丰厚。但这只是短期的经济效益，并且正如他所提到的，大面积地砍伐多样化的乡土树种并替代种植单一的人工杨树纯林的做法将带来一些长期的负面影响。这里我要补充一些负面影响：广泛地人工种植纯林不太可能提供可支持野外大量药用植物生长所需的多样栖息地。多数药用植物需要在天然的混林环境中才能茂盛生长，尤其才能产生传统药材中所需的化学物质。鸟类和其他野生生物在分布播种中扮演了关键的角色，因此在自然的森林、灌木丛及其他植被的生长中，以及在相关减缓土壤侵蚀过程中均十分重要。然而，单一种植的人工纯林使鸟类和其他物种的栖息地减小，因此也缩减了人们本能够从生物天然播种过程中的获取的好处。森林和野生生态学家可指出这类大量的单一种植可造成的更多的负面影响。另一方面，单一种植的操作人员可在造林设计过程中从这些科学家的提议中获益，进而避免单一种植的长期负面影响。W. Parham parham305@aol.com

Gaoming Jiang points out that poplar-based plywood can be readily manufactured from monoculture poplar plantations and sold profitably. This is a short-term economic gain but as he also notes the wholesale replacement of China’s native, mixed-species tree cover with monoculture poplar plantings can have some long-term undesirable ecological effects.

To add to his list of undesirable effects, here are a few others. Widespread, poplar monocultures are unlikely to provide the varied habitats needed to support growth of the wide range of medicinal plants collected in the wild. Many of these medicinal plants require a natural habitat of mixed species in order to thrive, and especially to produce the particular chemicals desired in traditional medicines.

Birds and other wildlife species play key roles in seed dispersal and thus in the natural spread of forest, shrub, and other vegetation and their associated beneficial effects of slowing soil erosion. Monoculture forests reduce the range of habitats for birds and other wildlife and thereby reduce the environmental and economic benefits people derive from wildlife seed-dispersal.

Forest and wildlife ecologists probably can point out additional adverse impacts that such extensive poplar monocultures can generate. On the other hand, monoculture-plantation operators probably could benefit from the advice of such scientists during the design phase to avoid long-term negative consequences.

W. Parham
parham305@aol.com

很好的文章。 抱歉我六个月以后才读到它。如果因为缺乏种在通往北京奥运会体育馆三个主要车道的杨树而使奥运会无法进行，那就可笑啦。
本评论由Meiyou Ye翻译

Great article. Sorry that I have been reading it 6 months later. It would be funny that the olympic games couldn't take place because of the lack of the last poplars going to be planted along the main three line avenue driving to the stadium.