Centre for Biodiversity and Biosecurity, School of Biological Sciences, The University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
Glob Chang Biol. 2014 Sep;20(9):2800-14. doi: 10.1111/gcb.12531. Epub 2014 Apr 26.
Climate change may facilitate alien species invasion into new areas, particularly for species from warm native ranges introduced into areas currently marginal for temperature. Although conclusions from modelling approaches and experimental studies are generally similar, combining the two approaches has rarely occurred. The aim of this study was to validate species distribution models by conducting field trials in sites of differing suitability as predicted by the models, thus increasing confidence in their ability to assess invasion risk. Three recently naturalized alien plants in New Zealand were used as study species (Archontophoenix cunninghamiana, Psidium guajava and Schefflera actinophylla): they originate from warm native ranges, are woody bird-dispersed species and of concern as potential weeds. Seedlings were grown in six sites across the country, differing both in climate and suitability (as predicted by the species distribution models). Seedling growth and survival were recorded over two summers and one or two winter seasons, and temperature and precipitation were monitored hourly at each site. Additionally, alien seedling performances were compared to those of closely related native species (Rhopalostylis sapida, Lophomyrtus bullata and Schefflera digitata). Furthermore, half of the seedlings were sprayed with pesticide, to investigate whether enemy release may influence performance. The results showed large differences in growth and survival of the alien species among the six sites. In the more suitable sites, performance was frequently higher compared to the native species. Leaf damage from invertebrate herbivory was low for both alien and native seedlings, with little evidence that the alien species should have an advantage over the native species because of enemy release. Correlations between performance in the field and predicted suitability of species distribution models were generally high. The projected increase in minimum temperature and reduced frosts with climate change may provide more suitable habitats and enable the spread of these species.
气候变化可能会促进外来物种入侵到新的地区，特别是对于那些来自温暖原生范围的物种，它们被引入到目前温度条件边缘的地区。虽然模型方法和实验研究的结论通常相似，但将这两种方法结合起来的情况很少发生。本研究的目的是通过在模型预测的不同适宜性的地点进行实地试验来验证物种分布模型，从而提高对其评估入侵风险能力的信心。本研究选择了新西兰的三种最近归化的外来植物作为研究物种（Archontophoenix cunninghamiana、Psidium guajava 和 Schefflera actinophylla）：它们来自温暖的原生范围，是木质的鸟类传播物种，被认为是潜在的杂草。在全国六个地点种植幼苗，这些地点在气候和适宜性方面存在差异（根据物种分布模型预测）。在两个夏季和一个或两个冬季季节中记录了幼苗的生长和存活情况，并在每个地点每小时监测温度和降水。此外，还比较了外来幼苗与亲缘关系密切的本地物种（Rhopalostylis sapida、Lophomyrtus bullata 和 Schefflera digitata）的表现。此外，还对一半的幼苗进行了喷洒农药处理，以调查是否会因天敌释放而影响其表现。结果表明，在六个地点中，外来物种的生长和存活存在很大差异。在更适宜的地点，其表现通常比本地物种更高。无脊椎动物食草动物对叶片的损害在本地和外来幼苗中都较低，几乎没有证据表明由于天敌释放，外来物种会比本地物种具有优势。在野外表现与物种分布模型预测的适宜性之间的相关性通常较高。气候变化导致最低温度增加和霜期减少，可能会提供更适宜的栖息地，并促进这些物种的传播。
