Influence of light and nutrient conditions on seedling growth of native and invasive trees in the Seychelles
Influence of light and nutrient conditions on seedling growth of native and invasive trees in the Seychelles
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DOI：
10.1007/s10530-008-9371-6
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发表时间：
2009-10
影响因子：
2.9
通讯作者：
E. Schumacher;C. Kueffer;P. Edwards;H. Dietz
中科院分区：
文献类型：
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作者：
E. Schumacher;C. Kueffer;P. Edwards;H. Dietz
最近的几项研究表明，植物入侵可能发生在资源贫乏和相对未受干扰的栖息地。因此，重要的是要调查是否以及如何在这样的栖息地入侵物种的生活史特征不同的物种，只有在干扰和资源丰富的栖息地入侵。我们比较了在热带塞舌尔营养不良的次生林的本地和入侵树种的幼苗的生长。我们假设，这两组的相对性能将改变可预见的沿着资源梯度，本地物种表现更好，在低水平的资源可用性和入侵物种表现更好，在更高的水平。为了验证这一假设，我们进行了一个共同的花园实验，使用幼苗的六个入侵和七个本地树种生长在三个级别的光（65，11和3.5%的环境光）和两个营养物质（低和高）。由于物种之间的差异很大，生长速率（RGR）的差异不显着之间的本地和入侵物种的幼苗。然而，入侵物种的幼苗表现出较高的比叶面积（SLA）和较高的叶片养分含量比本地物种的幼苗。它们在生物量和养分分配方面也表现出更大的可塑性（即，在LAR，RSR和叶片养分含量更大的可塑性）响应不同的资源可用性。然而，与组内变异相比，这些参数平均值之间的差异通常较小。我们的结论是，成功的入侵者在塞舌尔营养不良的土壤是耐应力，具有类似的本地物种的生长特性，或快速增长，但适应营养不良的土壤。相比之下，更典型的，快速增长的外来物种，没有特别的适应养分贫瘠的土壤似乎仅限于在低地相对养分丰富的网站。一些引进的物种在资源贫乏的栖息地茁壮成长，这一发现表明，资源可利用性低的未受干扰的栖息地对植物入侵的抵抗力可能比以前想象的要低。
Several recent studies have shown that plant invasions can occur in resource-poor and relatively undisturbed habitats. It is, therefore, important to investigate whether and how life-history traits of species invasive in such habitats differ from those of species that are only invasive in disturbed and resource rich habitats. We compared the growth of seedlings of native and invasive tree species from nutrient-poor secondary forests in the tropical Seychelles. We hypothesised that the relative performance of the two groups would change predictably along resource gradients, with native species performing better at low levels of resource availability and invasive species performing better at higher levels. To test this hypothesis, we performed a common garden experiment using seedlings of six invasive and seven native tree species grown under three levels of light (65, 11 and 3.5% of ambient light) and two of nutrients (low and high). Due to large variation among species, differences in growth rates (RGR) were not significant among seedlings of the native and the invasive species. However, seedlings of the invasive species showed higher specific leaf areas (SLA) and higher leaf nutrient contents than seedlings of the native species. They also exhibited greater plasticity in biomass and nutrient allocation (i.e., greater plasticity in LAR, RSR and leaf nutrient contents) in response to varying resource availability. However, differences between the mean values of these parameters were generally small compared with variation within groups. We conclude that successful invaders on nutrient-poor soils in the Seychelles are either stress-tolerant, possessing growth traits similar to those of the native species, or fast-growing but adapted to nutrient-poor soils. In contrast, the more typical, fast-growing alien species with no particular adaptations to nutrient-poor soils seem to be restricted to relative nutrient-rich sites in the lowlands. The finding—that some introduced species thrive in resource-poor habitats—suggests that undisturbed habitats with low resource availability may be less resistant to plant invasions than was previously supposed.