Bryophytes, lichens and phanerogams in an alvar grassland: relationships at different scales and contributions to plant community pattern



The relationship between bryophytes and lichens versus phanerogams has been investigated in three stands of a limestone grassland community, along three transects of 500 10 X 10 cm plots. Ordination axes resulting from Detrended Correspondence Analysis for bryophytes and lichens versus phanerogams were correlated using Spearman rank correlation coefficient. The effect of grain (sample plot) size on relationships between species along the gradient and on the correlation between the layers formed by bryophytes and lichens (cryptogams) and phanerogams, and with environmental variables has been as well examined. Values for light, moisture, pH and nitrogen have been derived from the vegetation itself with the help of Ellenberg indicator values. The relative position of species in the ordination space is more or less the same until grain size 3 (10 x 40 cm) for cryptogams and phanerogams and until grain size 2 (10 × 20 cm) for all-species together. Therefore, it is suggested that sample plot sizes of 10 × 10 cm to 10×20 cm are appropriate as units for field experiments testing interactions between cryptogams and phanerogams. The respective layers were weakly correlated and the correlation between them increased with increase in grain size. The correlation of DCA axis 1 from the ordination of cryptogams, phanerogams and all-species with the environmental factors was weak and similar in order of magnitude. Only the environmental variables which were strongly correlated with the DCA axis 1 increased in correlation at larger grain sizes. The ordinations of cryptogams, phanerogams and all-species were correlated along DCA axis 1 with pH in all investigated stands and at almost all grain sizes. Multi-species patches have been detected by pattern analysis (PASFRAN) on DCA sample scores from ordinations of cryptogams, phanerogams and combined matrices. Multi-species patterns with sizes between 20-240 cm. composed by bryophytes and lichens and by phanerogams have been found. Complex patterns formed by cryptogams and phanerogams together, which are different in size than those in the separate layers, suggest that bryophytes + lichens and phanerogams may interact with each other.