Baruch Z, Goldstein G
Departamento de Estudios Ambientales, Universidad Simón Bolívar, Aptdo 89000, Caracas 1080, Venezuela e-mail:
Department of Botany, University of Hawaii, 3190 Maile Way, Honolulu, HI 96822, USA, , , , , , US.
Oecologia. 1999 Nov;121(2):183-192. doi: 10.1007/s004420050920.
The effects of biological invasions are most evident in isolated oceanic islands such as the Hawaiian Archipelago, where invasive plant species are rapidly changing the composition and function of plant communities. In this study, we compared the specific leaf area (SLA), leaf tissue construction cost (CC), leaf nutrient concentration, and net CO assimilation (A) of 83 populations of 34 native and 30 invasive species spanning elevation and substrate age gradients on Mauna Loa volcano in the island of Hawaii. In this complex environmental matrix, where annual precipitation is higher than 1500 mm, we predicted that invasive species, as a group, will have leaf traits, such as higher SLA and A and lower leaf CC, which may result in more efficient capture of limiting resources (use more resources at a lower carbon cost) than native species. Overall, invasive species had higher SLA and A, and lower CC than native species, consistent with our prediction. SLA and foliar N and P were 22.5%, 30.5%, and 37.5% higher, respectively, in invasive species compared to native ones. Light-saturated photosynthesis was higher for invasive species (9.59 μmol m s) than for native species (7.31 μmol m s), and the difference was larger when A was expressed on a mass basis. Leaf construction costs, on the other hand, were lower for the invasive species (1.33 equivalents of glucose g) than for native species (1.37). This difference was larger when CC was expressed on an area basis. The trends in the above traits were maintained when groups of ecologically equivalent native and invasive species (i.e., sharing similar life history traits and growing in the same habitat) were compared. Foliar N and P were significantly higher in invasive species across all growth forms. Higher N may partially explain the higher A of invasive species. Despite relatively high N, the photosynthetic nitrogen use efficiency of invasive species was 15% higher than that of native species. These results suggest that invasive species may not only use resources more efficiently than native species, but may potentially demonstrate higher growth rates, consistent with their rapid spread in isolated oceanic islands.
生物入侵的影响在诸如夏威夷群岛等孤立的海洋岛屿上最为明显，在这些岛屿上，入侵植物物种正在迅速改变植物群落的组成和功能。在本研究中，我们比较了夏威夷岛莫纳罗亚火山上跨越海拔和基质年龄梯度的34种本地物种和30种入侵物种的83个种群的比叶面积（SLA）、叶组织构建成本（CC）、叶养分浓度和净CO₂同化率（A）。在这个年降水量高于1500毫米的复杂环境矩阵中，我们预测，作为一个群体，入侵物种将具有一些叶性状，如较高的SLA和A以及较低的叶CC，这可能导致它们比本地物种更有效地获取有限资源（以较低的碳成本利用更多资源）。总体而言，入侵物种的SLA和A高于本地物种，CC低于本地物种，这与我们的预测一致。与本地物种相比，入侵物种的SLA以及叶片中的氮和磷分别高出22.5%、30.5%和37.5%。入侵物种的光饱和光合作用（9.59 μmol m⁻² s⁻¹）高于本地物种（7.31 μmol m⁻² s⁻¹），当以质量为基础表示A时，差异更大。另一方面，入侵物种的叶构建成本（1.33克葡萄糖当量）低于本地物种（1.37克葡萄糖当量）。当以面积为基础表示CC时，这种差异更大。当比较生态等效的本地和入侵物种组（即具有相似生活史特征并生长在相同栖息地）时，上述性状的趋势得以维持。在所有生长形式中，入侵物种的叶片氮和磷含量均显著更高。较高的氮含量可能部分解释了入侵物种较高的A。尽管氮含量相对较高，但入侵物种的光合氮利用效率仍比本地物种高15%。这些结果表明，入侵物种不仅可能比本地物种更有效地利用资源，而且可能具有更高的生长速率，这与其在孤立海洋岛屿上的快速扩散相一致。
