优势花卉资源的入侵：对本地植物的花卉群落和授粉的影响
Ecology
Pub Date : 2017-01-01
DOI : 10.1002/ecy.1639
Karen Goodell 1 , Ingrid M Parker 2
通过对传粉者的竞争，入侵植物可能会抑制本地植物群。社区层面的研究提供了对入侵影响的综合评估，并深入了解了影响不同本地物种脆弱性的因素。我们调查了美国东部 14 分野中非本地草本植物 Lythrum salicaria 对本地物种授粉的影响。我们比较了入侵和未入侵沼泽中 122 种本地植物物种的每朵花的访客，并结合了景观规模的实验，从三个入侵的沼泽中去除了 L. salicaria 花。当 L. salicaria 开花时，侵入地点的总花密度是未侵入地点或清除地点的三倍以上。尽管每个地区的鲜花数量增加了游客数量，随着鲜花数量的增加，每朵本地花的访客量下降。因此，L. salicaria 入侵抑制了对本地花卉的访问。在移除地点，对原生花卉的访问与未受入侵的地点相似，证实了观察结果，也表明入侵并未导致访客数量持续增加。为了研究物种水平的影响，我们研究了入侵对在入侵和未入侵的沼泽中开花的 36 种植物物种每朵花的访客的影响。平均而言，入侵的影响意味着每朵花的访问量减少了约 20%。我们使用荟萃分析测量了植物性状对 L. salicaria 入侵脆弱性的影响。双侧对称的花朵对访问量的影响更大，并且花色与 L 相似。Salicaria 微弱地加强了与入侵者争夺游客的竞争。最后，我们评估了在优势开花灌木 Dasiphora fruticosa 中与入侵者竞争的生殖后果。尽管入侵对该物种的传粉媒介访问有负面影响，但种子生产的花粉限制在入侵地点并不比未入侵地点强，这表明对传粉媒介的竞争对其种群人口统计的影响很小。这种大量开花的入侵者对本地植物授粉的负面影响似乎是由总花密度的增加介导的，而传粉媒介密度的增加与这种增加不匹配。本地物种的花卉特征和生殖生态对影响的强度进行了调节。我们评估了在占优势的开花灌木 Dasiphora fruticosa 中与入侵者竞争的繁殖后果。尽管入侵对该物种的传粉媒介访问有负面影响，但种子生产的花粉限制在入侵地点并不比未入侵地点强，这表明对传粉媒介的竞争对其种群人口统计的影响很小。这种大量开花的入侵者对本地植物授粉的负面影响似乎是由总花密度的增加介导的，而传粉媒介密度的增加与这种增加不匹配。本地物种的花卉特征和生殖生态对影响的强度进行了调节。我们评估了在占优势的开花灌木 Dasiphora fruticosa 中与入侵者竞争的繁殖后果。尽管入侵对该物种的传粉媒介访问有负面影响，但种子生产的花粉限制在入侵地点并不比未入侵地点强，这表明对传粉媒介的竞争对其种群人口统计的影响很小。这种大量开花的入侵者对本地植物授粉的负面影响似乎是由总花密度的增加介导的，而传粉媒介密度的增加与这种增加不匹配。本地物种的花卉特征和生殖生态对影响的强度进行了调节。尽管入侵对该物种的传粉媒介访问有负面影响，但种子生产的花粉限制在入侵地点并不比未入侵地点强，这表明对传粉媒介的竞争对其种群人口统计的影响很小。这种大量开花的入侵者对本地植物授粉的负面影响似乎是由总花密度的增加介导的，而传粉媒介密度的增加与这种增加不匹配。本地物种的花卉特征和生殖生态对影响的强度进行了调节。尽管入侵对该物种的传粉媒介访问有负面影响，但种子生产的花粉限制在入侵地点并不比未入侵地点强，这表明对传粉媒介的竞争对其种群人口统计的影响很小。这种大量开花的入侵者对本地植物授粉的负面影响似乎是由总花密度的增加介导的，而传粉媒介密度的增加与这种增加不匹配。本地物种的花卉特征和生殖生态对影响的强度进行了调节。这种大量开花的入侵者对本地植物授粉的负面影响似乎是由总花密度的增加介导的，而传粉媒介密度的增加与这种增加不匹配。本地物种的花卉特征和生殖生态对影响的强度进行了调节。这种大量开花的入侵者对本地植物授粉的负面影响似乎是由总花密度的增加介导的，而传粉媒介密度的增加与这种增加不匹配。本地物种的花卉特征和生殖生态对影响的强度进行了调节。
Invasion of a dominant floral resource: effects on the floral community and pollination of native plants
Through competition for pollinators, invasive plants may suppress native flora. Community-level studies provide an integrative assessment of invasion impacts and insights into factors that influence the vulnerability of different native species. We investigated effects of the nonnative herb Lythrum salicaria on pollination of native species in 14 fens of the eastern United States. We compared visitors per flower for 122 native plant species in invaded and uninvaded fens and incorporated a landscape-scale experiment, removing L. salicaria flowers from three of the invaded fens. Total flower densities were more than three times higher in invaded than uninvaded or removal sites when L. salicaria was blooming. Despite an increase in number of visitors with number of flowers per area, visitors per native flower declined with increasing numbers of flowers. Therefore, L. salicaria invasion depressed visitation to native flowers. In removal sites, visitation to native flowers was similar to uninvaded sites, confirming the observational results and also suggesting that invasion had not generated a persistent build-up of visitor populations. To study species-level impacts, we examined effects of invasion on visitors per flower for the 36 plant species flowering in both invaded and uninvaded fens. On average, the effect of invasion represented about a 20% reduction in visits per flower. We measured the influence of plant traits on vulnerability to L. salicaria invasion using meta-analysis. Bilaterally symmetrical flowers experienced stronger impacts on visitation, and similarity in flower color to L. salicaria weakly intensified competition with the invader for visitors. Finally, we assessed the reproductive consequences of competition with the invader in a dominant flowering shrub, Dasiphora fruticosa. Despite the negative effect of invasion on pollinator visitation in this species, pollen limitation of seed production was not stronger in invaded than in uninvaded sites, suggesting little impact of competition for pollinators on its population demography. Negative effects on pollination of native plants by this copiously flowering invader appeared to be mediated by increases in total flower density that were not matched by increases in pollinator density. The strength of impact was modulated across native species by their floral traits and reproductive ecology.
