Dialytrichia undetermined

Philippe, Marc, Bittebiere, Anne-Kristel & Hugonnot, Vincent, 2019, Do Dialytrichia mucronata and D. saxicola share the same ecological preferences? A case study in the Rhône Valley (France) and possible application for river incision biomonitoring, Cryptogamie, Bryologie 20 (13), pp. 141-152 : 146-148

DIALYTRICHIA SPECIES GROUPING WITH OTHER BRYOPHYTES

Dialytrichia species were found to grow in association with 83 bryophyte species (See Appendix 1 and Supplementary material). Some were ecologically very different, as Fontinalis antipyretica Hedw. and Grimmia dissimulata E. Maier. The average species richness of the relevés with Dialytrichia was 5.43, despite the large number of species with which both were associated. In our research the assemblages with D. mucronata only were not significantly more species rich (average 5.14) than those with D. saxicola only (average 4.83). Assemblages with both species were more species rich than those with only one of the species (average 5.43).

The cumulative projected inertia for the first three axes of the multivariate analysis (correspondence analysis) was 23.26%. For the first two axes (Fig. 3) the inertia was only 16.82%. It is thus clear that the set of relevés was not strongly structured by a dominant factor.The two Dialytrichia species were mainly separated on the first axis and much less on the second axis.

Along axis 1, D. saxicola is close to Syntrichia laevipila Brid. , a mesophytic to slightly xerophytic species ( Dierssen 2001). At the opposite end of the same axis, D. mucronata is associated, though less strongly, with Cirriphyllum crassinervium (Taylor) Loeske & M. Fleisch. , Rhynchostegium riparioides (Hedw.) Cardot and Schistidium crassipilum H.H. Blom. While the last species has a large ecological spectrum, the two other species are hygroclinous ( Dierssen 2001). Hygrophytic species, such as Cinclidotus fontinaloides (Hedw.) P. Beauv. , had a median position along axis 1.

A set of three species ( Orthotrichum anomalum Hedw. , O. diaphanum Schrad. ex Brid. and Syntrichia latifolia (Bruch ex Hartm.) Huebener ) can be found at the extreme positions along axis 2. Orthotrichum anomalum is a saxicolous species, while O. diaphanum is nitrophilous, and S. latifolia develops on heavily silted substrates of flooded zones; the three species are related to mineral-rich conditions ( Dierssen 2001). At the negative end, although both hygrophilous, Anomodon attenuatus (Hedw.) Huebener and Cryphaea heteromalla (Hedw.) D. Mohr are typical for unsilted substrates outside of the flood zone. However, a species typical of frequently flooded and silted substrates, Didymodon sinuosus (Mitt.) Delogne ( Dierssen 2001; Hugonnot & Celle 2013) is found at the median position along axis 2.

Analyses of various sub-sets of the database were not performed. Based on field evidence, no clearer partitioning of the relevés was noted.