Biomass allocation to anchoring structures in the aquatic macrophytes from the subcontinental and Atlantic climates in Europe

Abstract

Biomass allocation to anchoring structures in 10 species of aquatic macrophytes in two types of the cool and humid temperate climate in Europe, subcontionental (NW Poland) and Atlantic (W France), was examined. The study focused on the weight of anchoring organs in Chara delicatula Ag., Ch. fragilis Desv., Juncus bulbosus L., Littorella uniflora (L.) Asch., Luronium natans (L.) Raf., Potamogeton pectinatus L., P. perfoliatus L., P. natans L. and Ranunculus fluitans (Lam.) Wimm., as well as submerged structures in Hydrocharis morsus-ranae L. The plants were collected from 10 geographically distant lakes and 2 rivers with a current velocity of 0.3-0.5 m s^-1. It was assumed that biomass allocation to anchoring structures in rooting macrophytes depends on the time that mechanical forces, which can remove the plants from the occupied area, exert their effect. It was found that, in the Atlantic and subcontinental climates, the ratio between the biomass of underground (or submerged) and above-ground structures (U/A index), calculated for the ramets of Chara fragilis, Hydrocharis morsus-ranae and Ranunculus fluitans, has similar values (p>0.05). Nevertheless, among seven species of Cormophyta, which were anchored in the lake or pond littoral, six (Juncus bulbosus, Littorella uniflora, Luronium natans, Potamogeton pectinatus, P. perfoliatus and P. natans) had higher values of the U/A index in the Atlantic climate than in the subcontinental type (p < 0.05). This can be explained by the lack of ice cover and, consequently, a longer time of wave action than in the subcontinental climate.