Does disturbance, competition or resource limitation underlie Hieracium lepidulum invasion in New Zealand? Mechanisms of establishment and persistence, and functional differentiation among invasive and native species.
Does disturbance, competition or resource limitation underlie Hieracium lepidulum invasion in New Zealand? Mechanisms of establishment and persistence, and functional differentiation among invasive and native species.
复制标题
干扰、竞争或资源限制是否是鳞叶螟入侵新西兰的原因？
DOI：
--
复制
发表时间：
2010
期刊：
影响因子：
--
通讯作者：
J. Lord
中科院分区：
文献类型：
--
作者：
I. Radford;K. Dickinson;J. Lord
植物入侵背后的过程一直是许多生态学研究的主题。了解植物入侵的机制很难从观测中阐明，但对入侵的生态管理至关重要。新西兰的星属入侵植物鳞片（Hieracium lepidulum）是一个可以提出几种解释机制的物种。本文提出了竞争优势、干扰常住植被导致竞争释放或养分资源限制减少与入侵者竞争的替代机制来解释入侵。我们通过对入侵前和入侵后植被的竞争环境、干扰环境和营养环境进行了实验，验证了这些假设。测量了鳞翅目和驻地对环境处理的反应，以解释其建立和持续存在的潜在机制。研究发现，鳞草在功能响应谱上与本地种存在差异。研究还发现，其他外来入侵植物的反应在功能上也与鳞草不同。这些数据支持了一种假设，即不同的入侵者使用不同的入侵机制。这些数据还表明，入侵植物和本地植被之间的功能差异可能是导致入侵的重要因素。鳞草对入侵后的植被几乎没有直接的竞争作用，这表明竞争不是维持其持久性的主要机制。在入侵前的植被中，有微弱的证据支持干扰能使鳞草初步建立，但干扰并没有导致入侵者的优势。尽管存在鳞草，但对添加的营养物质的快速竞争反应为驻地种的营养限制提供了强有力的支持。一旦营养限制得到缓解，鳞草的快速竞争性抑制表明营养限制可能是使入侵者占优势的重要过程。讨论了历史遗址退化和/或入侵引起的土壤化学/微生物变化在养分有效性中的可能作用。
The processes underlying plant invasions have been the subject of much ecological research. Understanding mechanisms of plant invasions are difficult to elucidate from observations, yet are crucial for ecological management of invasions. Hieracium lepidulum, an asteraceous invader in New Zealand, is a species for which several explanatory mechanisms can be raised. Alternative mechanisms, including competitive dominance, disturbance of resident vegetation allowing competitive release or nutrient resource limitation reducing competition with the invader are raised to explain invasion. We tested these hypotheses in two field experiments which manipulated competitive, disturbance and nutrient environments in pre-invasion and post-invasion vegetation. H. lepidulum and resident responses to environmental treatments were measured to allow interpretation of underlying mechanisms of establishment and persistence. We found that H. lepidulum differed in functional response profile from native species. We also found that other exotic invaders at the sites were functionally different to H. lepidulum in their responses. These data support the hypothesis that different invaders use different invasion mechanisms from one another. These data also suggest that functional differentiation between invaders and native resident vegetation may be an important contributing factor allowing invasion. H. lepidulum appeared to have little direct competitive effect on post-invasion vegetation, suggesting that competition was not a dominant mechanism maintaining its persistence. There was weak support for disturbance allowing initial establishment of H. lepidulum in pre-invasion vegetation, but disturbance did not lead to invader dominance. Strong support for nutrient limitation of resident species was provided by the rapid competitive responses with added nutrients despite presence of H. lepidulum. Rapid competitive suppression of H. lepidulum once nutrient limitation was alleviated suggests that nutrient limitation may be an important process allowing the invader to dominate. Possible roles of historical site degradation and/or invader-induced soil chemical/microbial changes in nutrient availability are discussed.