Dry grasslands of the Lesser Polish Upland: syntaxonomy, biodiversity and conservation

Dry (xerothermic) grasslands are biodiversity hotspots, but at the same time threatened throughout Europe by abandonment, land-use intensification or eutrophication. Dry grasslands in temperate Europe belong to the phytosociological classes Festuco-Brometea (on loamy soils) and Koelerio- Corynephoretea (on sandy soils). While the Festuco-Brometea have generally received much more attention in both conservation and syntaxonomy, the Koelerio-Corynephoretea are often largely neglected. We thus conducted a regional survey of all dry grassland types of the Lesser Polish Upland. We sampled 70 10-m2 vegetation plots with careful treatment of vascular plants, bryophytes and lichens and extensive soil analyses. Given the relatively low number of plots, we assigned them to well- established syntaxa of neighbouring regions and countries by expert assessment. For the resulting units we determined diagnostic species numerically based on standardized phi-values at all main syn- taxonomic ranks. We found that all the stands fit very well into modern classification systems of the two classes, as they have been established based on large datasets in neighbouring countries. We distinguished two classes, four orders, six alliances and nine association-rank units, of which eight matched existing associations. The Koelerio-Corynephoretea were represented by the orders Cory- nephoretalia canescentis (xeric acidic) with the alliance Corynephorion canescentis (Cetrario aculeatae-Corynephoretum canescentis), the Festuco-Sedetalia acris (xeric more base-rich) with the alliances Sileno conicae-Cerastion semidecandri (Sileno conicae-Cerastietum semidecandri) and Koelerion glaucae (Helichryso arenarii-Jasionetum montanae and Festuco psammophilae-Koelerietum glaucae) and the Trifolio arvensis-Festucetalia ovinae (meso-xeric) with the alliance Armerion elongatae (Diantho deltoidis-Armerietum elongatae and Sileno otitae-Festucetum trachyphyllae). The Festuco-Brometea were only represented by the meso-xeric order Brachypodietalia pinnati, but with two alliances, the floristically impoverished Nordic-Baltic Filipendulo vulgaris-Helictochloion pratensis (Peucedanum oreoselinum-Briza media community) and the subcontinental Cirsio- Brachypodion pinnati (Scabioso ochroleucae-Brachypodietum pinnati and Inuletum ensifoliae). The syntaxa on all four ranks were floristically well characterised, with most of the regional diagnostic species matching those established in neighbouring countries. The mean species richness of all taxonomic groups was lower in the Koelerio-Corynephoretea (29.4) than in the Festuco-Brometea (44.8), while the lichen richness was higher in the former. The stands in the study region were on average more diverse than those in NE Germany, which could be attributed to more southern location combined with the latitudinal diversity gradient. The Koelerio-Corynephoretea inhabited the sandy deposits along the rivers, the Festuco-Brometea mostly occurred on limestone bedrock on the hills of the region, except for the Filipendulo vulgaris-Helictochloion pratensis in the Nida valley. This study is an important step toward a data-driven modern syntaxonomic overview of all dry grasslands in Poland and helps to bring some “neglected” types into focus.