Influence of small climatic variations on the species composition of roadside grasslands
Godefroid, Sandrine; Tanghe, Martin
Relations between the distribution of Arrhenatheretalia species from roadside grasslands of southern Belgium and variations in climatic parameters are described on the basis of a statistical sampling procedure integrating multivariate techniques (cluster analysis and DCA-ordination). The authors examine the influence of small macroclimate features, such as mean annual rainfall (1100-1400 mm), mean annual temperature (7.0- 8.2 °C), mean annual number of frost days (90-120) and mean annual number of snow days (28-35), on the floristic composition of roadside grasslands from High Ardennes (525-570 m a.s.l.) (19 samplings) and Middle Ardennes ecological sectors (330-500 m a.s.l.) (26 samplings). Cluster analysis revealed two distinct clusters of vegetation samples which are likely to be arranged along a climatic gradient. Sample scores on the first DCA-axis were significantly correlated with climatic parameters. Mean annual number of frost days was the factor which best explained the differences between plots, when analysed with a linear regression. These results indicate that very small macroclimate variations in general and in the number of frost days in particular, are determinant of compositional variation in roadside plant communities.