食草作用可能会促进非本地植物在低纬度地区而不是高纬度地区的入侵。
Herbivory may promote a non-native plant invasion at low but not high latitudes.
机构信息
College of Plant Sciences & Technology, Huazhong Agricultural University, Wuhan, Hubei, China.
Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei, China.
出版信息
Ann Bot. 2019 Nov 15;124(5):819-827. doi: 10.1093/aob/mcz121.
BACKGROUND AND AIMS
The strengths of biotic interactions such as herbivory are expected to decrease with increasing latitude for native species. To what extent this applies to invasive species and what the consequences of this variation are for competition among native and invasive species remain unexplored. Here, herbivore impacts on the invasive plant Alternanthera philoxeroides and its competition with the native congener A. sessilis were estimated across latitudes in China.
METHODS
An common garden experiment spanning ten latitudinal degrees was conducted to test how herbivore impacts on A. philoxeroides and A. sessilis, and competition between them change with latitude. In addition, a field survey was conducted from 21°N to 36.8°N to test whether A. philoxeroides invasiveness changes with latitude in nature as a result of variations in herbivory.
KEY RESULTS
In the experiment, A. sessilis cover was significantly higher than A. philoxeroides cover when they competed in the absence of herbivores, but otherwise their cover was comparable at low latitude. However, A. philoxeroides cover was always higher on average than A. sessilis cover at middle latitude. At high latitude, only A. sessilis emerged in the second year. Herbivore abundance decreased with latitude and A. philoxeroides emerged earlier than A. sessilis at middle latitude. In the field survey, the ratio of A. philoxeroides to A. sessilis cover was hump shaped with latitude.
CONCLUSION
These results indicate that herbivory may promote A. philoxeroides invasion only at low latitude by altering the outcome of competition in favour of the invader and point to the importance of other factors, such as earlier emergence, in A. philoxeroides invasion at higher latitudes. These results suggest that the key factors promoting plant invasions might change with latitude, highlighting the importance of teasing apart the roles of multiple factors in plant invasions within a biogeographic framework.
背景与目的
对于本地物种而言，生物相互作用（如食草作用）的强度预计会随着纬度的增加而减弱。这种情况在多大程度上适用于入侵物种，以及这种变化对本地种和入侵种之间的竞争有何影响，目前仍不清楚。本研究在跨越中国的 10 个纬度范围内，评估了食草动物对入侵植物空心莲子草及其与本地种伴生种节节菜之间竞争的影响。
方法
进行了一个跨越 10 个纬度的田间实验，以检验食草动物对空心莲子草和节节菜的影响，以及它们之间的竞争如何随纬度而变化。此外，还从 21°N 到 36.8°N 进行了实地调查，以检验空心莲子草在自然状态下的入侵性是否因食草动物的变化而随纬度而变化。
主要结果
在实验中，当不存在食草动物时，节节菜的盖度明显高于空心莲子草，但在低纬度时，它们的盖度相当。然而，空心莲子草的盖度平均总是高于节节菜的盖度。在高纬度，只有节节菜在第二年出现。食草动物的丰度随纬度而减少，空心莲子草在中纬度比节节菜更早出现。在实地调查中，空心莲子草与节节菜盖度的比值随纬度呈驼峰状。
结论
这些结果表明，食草动物可能仅通过改变有利于入侵种的竞争结果，在低纬度促进空心莲子草的入侵，而在高纬度，空心莲子草的更早出现等其他因素则更为重要。这些结果表明，促进植物入侵的关键因素可能随纬度而变化，这突出了在生物地理框架内分解植物入侵中多个因素的作用的重要性。
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