Publication Date:
2014-06-05
Description:
ABSTRACT Aquatic plants (macrophytes) can have a large effect on river hydraulics and geomorphology. However, the extent to what plant morphological plasticity actively influences these feedbacks has received little scientific attention. The nymphaeid macrophyte species Nuphar lutea (L.) Smith is characterised by a distinct leaf duality. Floating leaves shade most of the submerged leaves thereby limiting light penetration. Despite their apparent negligible photosynthetic role, submerged leaves of N . lutea remain intact during summer and contribute a significant part to the total biomass. Our results indicate that the submerged leaves are crucial in plant-flow interactions and hence in the engineering potential of the plant, i.e. the capacity to locally reduce flow velocities and to promote sedimentation, including organic matter deposition. Plant individuals growing in running river water were compared to individuals from adjacent oxbow lake water. The number and size of submerged leaves were significantly higher for river standing individuals and the accumulated sediment contained significantly more organic matter, total nitrogen and total phosphorus, and was characterised by a lower C/N ratio and a finer grain size. We therefore argue that the submerged N . lutea canopy in rivers has the ability to create a high-nutrient, low hydrodynamic environment, resembling the conditions found in oxbow lakes. This article is protected by copyright. All rights reserved.
Print ISSN:
0197-9337
Electronic ISSN:
1096-9837
Topics:
Geography
,
Geosciences
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