Heather Kharouba
Associate Professor of Ecology, L’Université d’Ottawa/University of Ottawa
Invasive species are often looked upon with suspicion. From non-native “weeds” to insects and aquatic invaders, introduced (or non-native) species continue to be misunderstood — and consequently often mismanaged. Stated plainly, the vast majority of intentionally or unintentionally introduced species are not a threat to native ecosystems. Governments and conservation organizations spend an enormous amount of their time and funding targeting the control of invasive species. Yet, most introduced species removal efforts are ineffective, time-consuming and usually unsuccessful in the long term.
入侵物种常常受到怀疑。从非本地“杂草”到昆虫和水生入侵者，引进（或非本地）物种仍然被误解，因此经常管理不善。坦率地说，绝大多数有意或无意引入的物种不会对本地生态系统构成威胁。各国政府和保护组织花费了大量的时间和资金来控制入侵物种。然而，大多数引进物种清除工作都是无效的、耗时的，而且从长远来看通常不会成功。
Certainly, some invasive species — such as the zebra mussel or the emerald ash borer — can pose a threat to native habitats and efforts to control their spread are worthwhile. However, the vast majority of introduced species pose no danger at all to native ecosystems and in some cases can even provide new benefits. Simply put, an over-fixation on demonizing “invasive” species, and controlling their spread, is ultimately futile and limits our understanding.
当然，一些入侵物种——例如斑马贻贝或白蜡螟——可能对本地栖息地构成威胁，控制其蔓延的努力是值得的。然而，绝大多数引进物种对本地生态系统没有任何威胁，在某些情况下甚至可以提供新的好处。简而言之，过度关注妖魔化“入侵”物种并控制其扩散，最终是徒劳的，并且限制了我们的理解。
Contemporary conservation practice is complex and biased against introduced species with a focus on maintaining ecosystems as they were. This policy and practice, while well-meaning, is leading us to underestimate the positive roles that introduced species can play in maintaining ecosystem resiliency. At worst, these policies can even have unintended negative consequences for our ecosystems. For example, herbicide treatments designed to cull invasive plants have affected butterfly populations by unintentionally killing off native plants. What’s more, some invasive species can aid local ecosystems by helping to filter the air and water of contaminants, and some introduced species can be more drought-tolerant than native species in a world of increasingly human-modified climate extremes. More fundamentally, “fortress” conservation policies are likely ultimately futile. Introduced plants are here to stay and are already highly adapted to local habitats, making their eradication challenging and perhaps even counter-productive to overall ecosystem health.
当代的保护实践非常复杂，并且对引进物种存在偏见，重点是维持生态系统原样。这种政策和做法虽然是善意的，但却导致我们低估了引进物种在维持生态系统弹性方面可以发挥的积极作用。在最坏的情况下，这些政策甚至可能对我们的生态系统产生意想不到的负面影响。例如，旨在消灭入侵植物的除草剂治疗无意中杀死了本地植物，从而影响了蝴蝶种群。更重要的是，一些入侵物种可以通过帮助过滤空气和水中的污染物来帮助当地生态系统，并且在人类日益改变的极端气候世界中，一些引进物种可以比本地物种更耐旱。更根本的是，“堡垒”保护政策最终可能是徒劳的。引进的植物将继续存在，并且已经高度适应当地的栖息地，这使得根除它们具有挑战性，甚至可能对整体生态系统的健康产生反作用。
Increasing evidence suggests that some introduced species may even be more likely to adapt to certain climate extremes than native plants in that area. Finally, introduced plants often differ in their characteristics from native plants, meaning they can provide new roles or replace the roles formerly served by native plants. For example, the introduced Siberian elm has adapted well to river areas that are now too dry for native elms. The introduced elm has been found to contribute similar roles in the community, like photosynthesis and providing wildlife habitats. All this means that introduced plants could be well-placed to support, or even buffer, current ecosystems as they undergo transitions due to climate change.
越来越多的证据表明，一些引进物种甚至可能比该地区的本土植物更有可能适应某些极端气候。最后，引入的植物通常在特性上与本地植物不同，这意味着它们可以提供新的角色或取代本地植物以前所扮演的角色。例如，引进的西伯利亚榆树已经很好地适应了河流地区，而这些地区现在对于本土榆树来说太干燥了。人们发现引入的榆树在社区中发挥着类似的作用，例如光合作用和提供野生动物栖息地。所有这一切都意味着，引进的植物可以很好地支持甚至缓冲当前生态系统因气候变化而发生的转变。
To move the needle on this challenge, scientists need to better understand cases where introduced plants have the potential to contribute to our ecosystems. Through regular study, monitoring and a holistic ecosystem-wide viewpoint, we can prioritize which introduced plants we need to try to remove and which we may be able to leave. Or, indeed, whether supplemental additions of native (or introduced) species may be needed in a particular case. Subjectively, we as a society need to decide how to weigh the relative importance of competing aspects of ecosystem functions over others. In the deciduous forests of the eastern United States, introduced shrub and liana species have increased carbon sequestration, although they’ve also reduced the abundance of flowering plants. In another example, the introduced humulus japonicus vine in river habitats in southern France reduced vine diversity but increased height of the plants, resulting in more photosynthesis. How we weigh the various pros and cons is as much a cultural and philosophical question as it is purely scientific.
为了应对这一挑战，科学家需要更好地了解引进植物有可能为我们的生态系统做出贡献的案例。通过定期研究、监测和整体生态系统的观点，我们可以优先考虑哪些引入的植物需要尝试去除，哪些可以保留。或者，实际上，在特定情况下是否需要补充添加本地（或引进）物种。主观上，我们作为一个社会需要决定如何权衡生态系统功能的竞争方面相对于其他方面的相对重要性。在美国东部的落叶林中，引入的灌木和藤本植物增加了碳固存，尽管它们也减少了开花植物的丰度。在另一个例子中，在法国南部的河流栖息地引入葎草藤减少了藤蔓的多样性，但增加了植物的高度，从而导致更多的光合作用。我们如何权衡各种利弊既是一个文化和哲学问题，也是一个纯粹的科学问题。
I am not suggesting that introduced plants do not have negative impacts on our ecosystems. Nor that we should abandon our efforts to mitigate serious problems caused by some introduced species or that governments should stop trying to prevent potentially harmful species from entering their jurisdictions. Rather, I urge conservation practitioners and policymakers to organize and prioritize the management and restoration of habitats based on the net benefit (or harm) of a species to an ecological community, instead of on the origin of the species. Restoration plans could also better consider the potential ramifications of introduced species removal on the community. For example, legumes which are a source of high quality pollen for bees and nitrogen for the plant community, are often removed in tallgrass prairies.
我并不是说引进的植物不会对我们的生态系统产生负面影响。我们也不应该放弃减轻某些引进物种造成的严重问题的努力，或者政府应该停止阻止潜在有害物种进入其管辖范围的努力。相反，我敦促保护从业者和政策制定者根据物种对生态群落的净效益（或危害）而不是物种的起源来组织和优先考虑栖息地的管理和恢复。恢复计划还可以更好地考虑引进物种清除对社区的潜在影响。例如，豆科植物是蜜蜂优质花粉和植物群落氮的来源，但在高草草原上经常被清除。
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