Der soziologische konnex der 47 häufigsten makrophyten der gewässer mitteleuropas

Summary

Phytosociological species groups within the classes Lemnetea and Potametea are investigated on the basis of 3000 relevés. The relations between species are calculated with the coefficient of Hamming and a % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeq4Xdm2aaW% baaSqabeaacaqGYaaaaaaa!3885!\[\chi ^{\text{2}} \]. The results are presented in the form of a table with the species ordered in a linear sequence as well as in a plexus diagram. The 47 most frequent species are grouped into 4 clusters and the significance of these phyto-sociological species groups for the syntaxonomy of aquatic communities is discussed. Cluster 1 shows many high contingency values. It comprises the pleustophytic species of the Lemnetea. The isolated position of Utricularia vulgaris, the almost identical contingency profiles of Lemna minor and Spirodela polyrrhiza, the contrast between Lemna gibba versus Lemna trisulca, Riccia fluitans and Ricciocarpus natans, and the strong relation between Hydrocharis and Stratiotes are emphasized.

The remaining species are characteristic for the Potametea complex. Cluster 2 represents the competitive species of the magnonymphaeid and magnopotamid growth form while clusters 3 and 4 are composed of parvopotamids and batrachids. As to cluster 2 the division of the ‘Nymphaeion’ group into a subset with Myriophyllum verticillatum, Nuphar luteum and Nymphaea alba and one with Trapa natans and Nymphoides peltata, the strong correlation of Potamogeton lucens, P. perfoliatus, Myriophyllum spicatum and Ranunculus circinatus, the connecting position of Ceratophyllum demersum and the isolated position of Polygonum amphibium are emphasized. Cluster 3 is subdivided into several overlapping subgroups. Remarkable is the contrast of stenotopic species groups (Najas marina, Potamogeton gramineus; Callitriche hamulata, Myriophyllum alterniflorum) and eurytopic species groups (Potamogeton pectinatus, P. pusillus; P. crispus, P. friesii; Callitriche platycarpa, Ranunculus peltatus). A clear division into ‘Parvopotamion’- and ‘Callitricho-Batrachion’-species cannot be found. Hydrophytic differential species of a ‘Ranunculion fluitantis’ are also absent. Hottonia palustris shows special relations to a group of mesotrophic species.

Cluster 4 is closely related to several subgroups of cluster 3. The high contingency coefficients are caused by the common occurrence of these species in calcium-rich running waters. Hippuris vulgaris shows a distribution which is very difficult to interpret. Potamogeton coloratus is another rather isolated species.

Finally, the ordination of species by phytosociological affinity is compared with the hydrochemical data for 31 species that are frequent in southern Lower Saxony (ef. Wiegleb 1976). It is estimated that the hydrochemistry accounts for only 20 to 25 percent of the observed phytosociological variance. Other factors, e.g. water depth, motion, and temperature may not be neglected.