Standen Katherine M, Chambers Patricia A, Culp Joseph M
1Biology Department and Canadian Rivers Institute, University of New Brunswick, PO Box 4400, Fredericton, NB E3B 5A3 Canada.
2Environment and Climate Change Canada, 867 Lakeshore Rd, PO Box 5050, Burlington, ON L7R 4A6 Canada.
Wetl Ecol Manag. 2018;26(3):331-343. doi: 10.1007/s11273-017-9576-5. Epub 2017 Sep 27.
The emergent aquatic plant, is an easily-identified and commonly-found species in the Great Plains region of North America and has the potential to be a bioindicator of nitrogen (N) and phosphorus (P) because of its previously-identified leaf plasticity in response to nutrient conditions. To identify associations between leaf morphology and soil and water nutrients, we conducted: (1) a 10-week controlled experiment in which plants were grown in nutrient-enriched sediment, nutrient-enriched water, or unamended control trials, and (2) a field study where emergent leaves were collected from 15 streams of varying nutrient concentrations. Plants grown in experimentally enriched sediment were more productive than those grown in enriched water or control conditions: they produced more emergent leaves and tubers, had a larger final biomass and height, and developed emergent leaves that showed a consistent increase in size and unique change in shape over time. Emergent leaves collected from field plants also showed significant variability of leaf traits; however, this variability occurred at all scales of replication (leaf, plant, quadrat, and site), with linear mixed effects modelling indicating that random chance was likely driving this variability. Although sediment nutrients were crucial to successful growth of under controlled conditions, the high variability in leaf morphology under field conditions (likely due to large natural variability at the species, population, and individual scale) make leaf plasticity of unsuitable as a bioindicator. Our results emphasize the need to quantify within and among plant variation in leaf morphology (and to clarify sampling methods) for the many taxa of aquatic macrophytes that are phenotypically plastic and notoriously difficult to classify.
这种挺水植物是北美大平原地区一种易于识别且常见的物种，由于其先前已被确认的叶片对养分条件的可塑性，它有可能成为氮（N）和磷（P）的生物指示物。为了确定叶片形态与土壤和水体养分之间的关联，我们进行了：（1）一项为期10周的对照实验，其中植物分别种植在营养丰富的沉积物、营养丰富的水中或未改良的对照试验中；（2）一项实地研究，从15条养分浓度各异的溪流中采集挺水叶片。在实验性富营养沉积物中生长的植物比在富营养水中或对照条件下生长的植物更具生产力：它们长出了更多的挺水叶片和块茎，最终生物量和高度更大，并且长出的挺水叶片随着时间推移尺寸持续增加且形状发生独特变化。从野外植物采集的挺水叶片也显示出叶片性状的显著变异性；然而，这种变异性在所有复制尺度（叶片、植株、样方和地点）上都存在，线性混合效应模型表明随机因素可能导致了这种变异性。尽管在对照条件下沉积物养分对该植物的成功生长至关重要，但野外条件下叶片形态的高变异性（可能是由于物种、种群和个体尺度上的巨大自然变异性所致）使得该植物的叶片可塑性不适于作为生物指示物。我们的结果强调，对于许多表型具有可塑性且 notoriously difficult to classify（此处疑有误，可能是“ notoriously difficult to classify准确翻译为‘极难分类’”）的水生大型植物分类群，需要量化叶片形态在植物内部和之间的变异（并阐明采样方法）。
