Descriptive vegetation science has witnessed a rapid progress in the last
decades
due to the improvement of broad-scale electronic databases. Most synthetic
works aimed
at delimiting vegetation types on the basis of numerical analysis of
species composition
of sample plots. Such classifications are often supposed to serve as a
multi-purpose reference
of habitat types, since the diversity and composition of natural
communities are known
to determine general ecosystem properties. However, it has been recognised
that focusing
on species composition may fail to reveal certain patterns of vegetation
that are strongly
linked with the functioning of ecosystems. Instead of the taxonomic
identities of species,
their functional traits could offer more relevant information. Functional
classifications
are expected to have more general validity than species-based
classifications because
often the same traits respond to the same environmental gradients in very
different places
of the world due to convergent evolution. In contrast, species are
dispersal-limited,
thus their local abundances are informative only within their respective
distributional limits.
Our aim was to classify managed herbaceous vegetation on deep soils and
temperate climate
of Molinio-Arrhenatheretea syntaxonomical class in Poland on the basis of
phytosociological
relevés, plant trait data, and using numerical methods.
19995 vegetation plots representing all major grassland types of Poland
were
retrieved from the Polish Vegetation Database, from which a narrower
subset
of cca. 6000 Molinio-Arrhenatheretea relevés were resampled. Records of
specific leaf
area, canopy height, seed mass, clonality and bud bank were obtained from
the LEDA
and CLO-PLA databases. Between-plot dissimilarities were expressed by Rao
functional
dissimilarity index. The dissimilarity matrix was passed to principal
coordinates ordination,
and its most important axes were classified by Ward’s method.
Although, this classification did not reproduce the hierarchy of the
syntaxonomical
categories at a coarse scale, at finer resolutions the main subtypes of
MolinioArrhenatheretea
were differentiated: mesic and wet hay meadows and pastures,
marshes and wet grasslands rich in sedges, tall-forb vegetation, and
trampled grasslands.
After the first promising results, more subtle differences between types
in individual traits
are subject to further research.
