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 <em>Chara delicatula</em> Ag., <em>Ch. fragilis</em> Desv., <em>Juncus bulbosus</em> L., <em>Littorella uniflora</em> (L.) Asch., <em>Luronium natans</em> (L.) Raf., <em>Potamogeton pectinatus</em> L., <em>P. perfoliatus </em>L., <em>P. natans</em> L. and <em>Ranunculus fluitans</em> (Lam.) Wimm., as well as submerged structures in <em>Hydrocharis morsus-ranae</em> L. The plants were collected from 10 geographically distant lakes and 2 rivers with a current velocity of 0.3-0.5 m s<sup>-1</sup>. 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 <em>Chara fragilis</em>, <em>Hydrocharis morsus-ranae</em> and <em>Ranunculus fluitans</em>, has similar values (p&gt;0.05). Nevertheless, among seven species of <em>Cormophyta</em>, which were anchored in the lake or pond littoral, six (<em>Juncus bulbosus</em>, <em>Littorella uniflora</em>, <em>Luronium natans</em>, <em>Potamogeton pectinatus</em>, <em>P. perfoliatus</em> and <em>P. natans</em>) had higher values of the U/A index in the Atlantic climate than in the subcontinental type (p &lt; 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.
Highlights
Populations of inland macrophytes, as well as water bodies in which they occur, have a scattered, island-like distribution in each dimension of geographical space
We studied biomass allocation to anchoring structures in 10 species of aquatic macrophytes, including 9 which have contact with the substrate (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.) and one pleustophyte (Hydrocharis morsus-ranae L.)
Out of seven aquatic species of Cormophyta which anchor themselves in the littoral zone of lakes or ponds, six (Juncus bulbosus, Littorella uniflora, Luronium natans, Potamogeton pectinatus, P. perfoliatus and P. natans) have higher biomass ratios between underground and above-ground structures (U/A index) in the Atlantic climate than in the subcontinental type (Fig. 2)
Summary
Populations of inland macrophytes, as well as water bodies in which they occur, have a scattered, island-like (discontinuous) distribution in each dimension of geographical space (local, regional or continental). Geographical ranges of most aquatic plants are broad and generally cover a few climatic zones (Sculthorpe 1967; Walter and Straka 1970; Hutchinson 1975; Walter et al 1975; Hultén and Fries 1986). Without doubt there are many causes of such distribution. According to Santamaría (2002), a limited effect of the climate itself can be one of them. This is an interesting viewpoint, but it has not been definitively proven yet. The fact that the results of the climate effect are visible mainly in the disjunctions at the junction of major climate types, that is tropical, temperate and subarctic The fact that the results of the climate effect are visible mainly in the disjunctions at the junction of major climate types, that is tropical, temperate and subarctic (op. cit.), is not a persuasive evidence for the legitimacy of this claim
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