Understanding determinants of plant invasiveness: a case study on tree mallow Lavatera arborea

我们发现媒体非常热衷于报道我们对苏格兰树锦葵的初步研究，部分原因是它对海雀的影响，海雀是一种受欢迎的保护标志。因此，我们选择从这个角度来展示我们的工作，将其作为一个有效的平台来接触人们，并随后告知他们关于植物入侵决定因素的拟议研究。换句话说，下面的文本可能是在开始研究时发出的典型新闻稿。海雀是英国最著名的海鸟之一，由于一种快速生长的外来植物入侵，它正被迫离开苏格兰的一些海鸟岛。科学家们发现，茂密的树葵高达3米，正在窒息海雀的繁殖地，并警告说，这种植物很快就会开始影响其他沿海繁殖鸟类，如鸬鹚、绒鸭、鲱鱼鸥和管鼻鹱。树锦葵，Lavatera arborea，一种大西洋-地中海沿岸的植物，原产于沿海地区，据信在苏格兰被种植在沿海花园后逃到了野外。虽然在封闭的地方存在了几百年，但这种植物突然变得具有侵略性，接管了岛屿生态系统，从而抑制了地面繁殖的鸟类和本地植被。这种快速扩张的原因是温暖的冬天，具有讽刺意味的是，繁殖海鸟数量的增加给土壤施肥，并通过挖洞和践踏来扰乱植被。海鸟栖息地中富含粪便的光秃秃的斑块现在是锦葵生长的地方，并逐渐入侵岛屿生态系统。这个问题不仅发生在苏格兰，澳大利亚和新西兰的岛屿上的海鸟也被锦葵挤占了。尽管在其非本地范围的部分地区是一个优越的竞争对手，但锦葵在英国西南部并没有入侵，它在最后一个冰河时期幸存下来，并与其他植物物种和谐相处。这种“杰基尔博士式”的行为变化似乎发生在许多植物身上，只有当它们被引入新环境时，才会表现出入侵性。了解为什么植物在一个地方具有侵略性，而在另一个地方却没有，变得至关重要。一旦确定，入侵植物对本地动植物的负面影响以及控制它们的相关操作成本就会急剧上升，因此更好的策略是识别高风险物种并采取措施防止这种情况发生。然而，我们需要知道问题可能在哪里以及如何出现，以便能够准确地针对这些预防措施。阿伯丁大学的科学家们建议研究侵入性和非侵入性范围，而不是坐在桌子后面讨论问题。类似的实验将在苏格兰和康沃尔进行，在这些实验中，似乎有利于锦葵生长的环境被模拟出来：加入鸟类的鸟粪，像海鸟在它们的繁殖地那样干扰植被。此外，一半的地点将受到保护，不受兔子和羊等食草动物的侵害，因为它们对不耐食草的树锦葵的胃口似乎也起着关键作用。在这两个地方，将比较来自苏格兰和康沃尔的锦葵植物的生长情况，以揭示苏格兰的植物是否有什么特殊之处，或者锦葵生长的条件是否决定了它是否真的会变成入侵性的，并导致生物多样性的丧失。入侵植物是全球生物多样性的主要威胁，据估计，全球每年因入侵植物造成的经济损失远远超过870亿美元。我们希望我们对这一单一植物物种的研究能给我们提供一些见解，帮助我们找到限制入侵物种进一步传播的最佳方法，从而造福于我们的自然环境。

We have found the media to be extremely keen to report on our initial studies on tree mallow in Scotland, partly because of its impact on puffins, a popular conservation icon. Hence, we have chosen to present the proposed work in this light, using it as an effective platform to reach people and subsequently inform them about the proposed study on determinants of plant invasiveness. In other words, the text below could be a typical press release send out upon initiating the study. One of Britain's best known seabirds, the puffin, is being forced out of a number of Scottish seabird island colonies by an invading fast-growing alien plant species. Scientists have discovered that dense stands of tree mallow, growing up to 3 metres tall, are choking puffin breeding sites and have warned that the plant could soon start affecting other coastal breeding birds such as cormorant, eider duck, herring gull and fulmar. Tree mallow, Lavatera arborea, an Atlantic-Mediterranean plant native to coasts, is believed to have escaped into the wild in Scotland after being planted in coastal gardens. Whilst present in confined places for several hundreds of years, the plant has suddenly become invasive, taking over island ecosystems and thereby suppressing ground breeding birds and native vegetation. The reasons for this rapid expansion are milder winters and, ironically, an increase in the number of breeding seabirds who fertilise the soil and disturb the vegetation through burrowing and trampling. Manure-rich, bare patches in seabird colonies are now the places where tree mallow establishes and from which they gradually invade island ecosystems. The problem occurs not only in Scotland, but islands in Australia and New Zealand are also having their seabirds squeezed out as tree mallow takes over. Despite being a superior competitor in parts of its non-native range, tree mallow is not invasive in the southwest of the UK, where it survided the last ice age and lives among other plant species in harmony. This 'Dr. Jekyl-style' change in behaviour seems to occur in many plants, with only their invasive character shown when introduced to new environments. Understanding why plants can be invasive in one place whilst not in another has become essential. Once established, the negative effects of invasive plants on native plants and animals, and the associated costs of operations to control them, rise steeply, so a better strategy is to identify high risk species and take measures to prevent this from happening. However, we need to know where and how the problems are likely to arise so that these preventative measures can be targeted precisely. Rather than discussing problems from behind a desk, scientists from the University of Aberdeen propose to study both invasive and non-invasive ranges. Parallel experiments will be set up in Scotland and Cornwall in which conditions that seem to favour tree mallow are being mimicked: guano from birds will be added, and the vegetation disturbed just like seabirds do in their breeding colonies. Moreover, half of the sites will be protected from grazers such as rabbits and sheep as their appetite for the grazing-intolerant tree mallow seems also to play a critical role. In both places, the growth of tree mallow plants from Scotland and Cornwall will be compared to reveal whether Scottish plants are something special, or whether the conditions under which tree mallow grows determines whether or not it will actually turn invasive and cause biodiversity loss. Invasive plants are a major threat to global biodiversity, and their economic costs are estimated to be far in excess of $87 billion U.S. per year worldwide. We hope that our research on this single plant species will give us insights that help finding ways how best to limit further spread of invasives, to the benefit of our natural environment.