Freckleton R P, Stephens P A, Sutherland W J, Watkinson A R
Department of Zoology, University of Oxford, UK.
Proc Biol Sci. 2004 Feb 7;271(1536):325-31. doi: 10.1098/rspb.2003.2603.
It has been suggested that genetically modified herbicide-tolerant crops may benefit biodiversity because spraying of crops may be delayed until later in the growing season, allowing weeds to grow during the early part of the year. This provides an enhanced resource for arthropods, and potentially benefits birds that feed on these. Thus, this technology could enhance biodiversity. Using a review of weed phenologies and a population model, we show that many weeds are unlikely to benefit because spraying is generally delayed insufficiently late in the season to allow most to set seed. The positive effects on biodiversity observed in trials lasting one or two seasons are thus likely to be transient. For one weed of particular significance (Chenopodium album, fat hen) we show that it is unlikely that the positive effects observed could be maintained by inputs of seed during other parts of the rotation. However, we find preliminary evidence that if spraying can be ceased earlier in the season, then a viable population of late-emerging weeds could be maintained. This strategy could benefit weeds in both genetically modified (GM) and non-GM crops, but would probably lead to reduced inputs in GM systems compared with conventional ones.
有人认为，转基因抗除草剂作物可能有益于生物多样性，因为作物喷洒除草剂的时间可能会推迟到生长季节后期，这样在年初时杂草就能生长。这为节肢动物提供了更多资源，并可能使以这些节肢动物为食的鸟类受益。因此，这项技术可以增强生物多样性。通过对杂草物候的综述和种群模型，我们表明许多杂草不太可能从中受益，因为喷洒除草剂的时间通常推迟得不够晚，以至于大多数杂草无法结籽。因此，在持续一两个季节的试验中观察到的对生物多样性的积极影响可能是短暂的。对于一种特别重要的杂草（藜，肥猪草），我们表明，在轮作的其他时期通过种子输入来维持观察到的积极影响不太可能。然而，我们发现初步证据表明，如果能在季节早期停止喷洒除草剂，那么晚出杂草的可行种群就可以维持。这一策略对转基因作物和非转基因作物中的杂草都有益，但与传统系统相比，转基因系统中的投入可能会减少。
