Syntaxonomy of the xero-mesophytic oak forests in the Republic of Tatarstan (Eastern Europe)

Aims: To develop a syntaxonomic classification of the xero-mesophytic broad-leaved oak forests of the Republic of Tatarstan with a preliminary analysis of their unique ecological features. Study area: The Republic of Tatarstan (European part of the Russian Federation). Methods: A total of 91 relevés were processed. Most of them (73.6%) were sampled in Tatarstan during 2016 and 2017, the remaining ones (26.4%) were historical published data. They were classified by means of a modified TWINSPAN algorithm using total inertia as a heterogeneity measure. Diagnostic, constant, and dominant species were identified using analytical tools in the JUICE 7.0 program. Results: The xero-mesophytic forests of the study area were assigned to four clusters. We describe two of them as new associations: Astragalo ciceri-Quercetum roboris ass. nova and Sanguisorbo officinalis-Quercetum roboris ass. nova. We classify them within the class Quercetea pubescentis. Conclusions: Our study is the first attempt to classify thermophilous and xero-mesophytic oak forests of the Republic of Tatarstan using the Braun-Blanquet system.

Taxonomic reference: Czerepanov (1995).

Syntaxonomic reference: Mucina et al. (2016) unless stated otherwise in the text.

Abbreviations: GIVD = Global Index of Vegetation-Plot Databases; NMDS = Non-metric multidimensional scaling.