Department of Animal Ecology and Physiology, Research Institute for Biological and Environmental Sciences (RIBES), Radboud University, Nijmegen, Netherlands.
Department of Particle Physics, Institute for Mathematics, Astrophysics and Particle Physics, Radboud University, Nijmegen, Netherlands.
PeerJ. 2022 Sep 1;10:e13976. doi: 10.7717/peerj.13976. eCollection 2022.
Nymphaeid macrophytes, rooting in the sediment of water bodies and characterized by floating leaves, play an important role in wetland ecosystems. The present research deals with the effects of limited space, limited nutrient availability, water temperature and an unexpected inundation on the production, turnover and plasticity of floating leaves of the globally widespread species (Fringed waterlily).
The effects of these environmental conditions were studied in two plots in outdoor concrete tanks (CT1, CT2, mesocosms simulating occurrence in small ponds) and in two plots in the floodplain oxbow lake Bemmelse Strang (BS1, BS2). Plot CT1 was situated in a stand coexisting with helophytes, plot CT2 in a monospecific stand, plot BS1 in the center and plot BS2 at the open water border of a monospecific stand. All floating leaf blades within the plots were marked at appearance at the water surface and subsequently length, width and damage of each leaf and maximum and minimum water temperatures were measured bi-weekly. Area and biomass of leaf blades were calculated based on leaf length and width and were used to calculate turnover rates and production.
The growth period started in May and ended mid-October with continuous production of floating leaves during nearly the whole vegetation period. In the tanks the water level was very stable, but the lake underwent an inundation by river water, causing a sudden loss of existing leaves. Considering environmental conditions and based on the assumed ranking from low to high nutrient availability, the ranking of the plots was CT1, CT2, BS1, BS2. This order was found for maximum leaf life span and maximum leaf length, and the reverse order was found for number of leaves, new leaves per day and duration of the vegetation period. Turnover rates appeared to be relatively similar for plots CT1, CT2 and BS1, but for the deeper border plot BS2 lower ratios were found. These results indicate that increased enclosure with expected nutrient limitation causes (1) the production of high numbers of small leaves with larger totals for leaf area and biomass, (2) a shift towards increased sexual reproduction by the production of more flowering stem leaves.
沼生大型植物，扎根于水体沉积物中，具有浮叶特征，在湿地生态系统中发挥着重要作用。本研究探讨了有限空间、有限养分可用性、水温和意外洪泛对全球广泛分布的物种（尖瓣野菱）浮叶的生产、周转率和可塑性的影响。
在两个户外混凝土水箱（CT1、CT2，模拟小池塘中发生情况的中观模型）和两个贝姆塞尔斯特朗河漫滩湖（BS1、BS2）的plots 中研究了这些环境条件的影响。plot CT1 位于与水生植物共存的林分中，plot CT2 位于单一种群林分中，plot BS1 位于中心，plot BS2 位于单一种群林分的开阔水面边界。每个plots 内所有浮出水面的叶片在出现时都被标记，并随后测量每个叶片的长度、宽度和损伤以及最大和最小水温。根据叶片长度和宽度计算叶片面积和生物量，并用于计算周转率和生产力。
生长期从 5 月开始，10 月中旬结束，几乎在整个植被期内持续产生浮叶。在水箱中，水位非常稳定，但湖泊受到河水泛滥的影响，导致现有叶片突然损失。考虑到环境条件，并根据假定的从低到高养分可用性的等级，plots 的等级为 CT1、CT2、BS1、BS2。这个等级与最大叶片寿命和最大叶片长度有关，而叶片数量、每天新叶片和植被期的逆序。周转率似乎对 plots CT1、CT2 和 BS1 相对相似，但对于较深的边界 plot BS2 则发现较低的比值。这些结果表明，增加围封并预期养分限制会导致（1）产生大量小叶片，总叶面积和生物量较大，（2）通过产生更多开花茎叶，转向增加有性繁殖。
