According to Kovar-Eder & Kvaček (2007), a system of vegetation types for Cenozoic forests and aquatic communities introduced by Mai (1981, 1985, 1995) is extremely detailed, but hardly applicable in a more general scale across Europe. Moreover, it is based on the nearest extant analogues, but the vegetation types are not objectively defined. Kovar-Eder & Kvaček (2007) characterized these basic terms as follows. NATURAL VEGETATION is in equilibrium with climatic and edaphic factors. It includes zonal (= climax), extrazonal, and azonal (= intrazonal) vegetation formations. Due to human impact, natural vegetation does not exist over large areas today. ZONAL VEGETATION: Large-scale vegetation developing under mesic soil conditions (no extremes). It is more distinctly influenced by climatic than by edaphic factors. EXTRAZONAL VEGETATION: Due to more extreme climatic or edaphic conditions at the geographic limits of their natural distribution area, vegetation formations may change their composition (e.g. from low to higher elevation). AZONAL VEGETATION: The development of plant communities is more strongly influenced by ground water surface than by climate (e.g., wetland, alluvial vegetation, mangroves).
The following six vegetation units were defined for zonal vegetation formations (Kovar-Eder et al. 2008, table 4):
1) Zonal temperate to warm-temperate broad-leaved deciduous forest (= Broad-leaved Deciduous Forest “BLDF”) is defined by BLD component attaining ≥ 80% of the zonal woody angiosperms and ZONAL HERB ≤ 30%;
2) Zonal warm-temperate to subtropical mixed mesophytic forest (= Mixed Mesophytic Forest “MMF”) is characterized as BLD < 80%, BLE < 30%, SCL + LEG < 20% and ZONAL HERB < 30%;
3) Zonal subtropical broad-leaved evergreen forest (= Broad-leaved Evergreen Forest “BLEF”) is defined by these proportions of the components BLE ≥ 30%, SCL + LEG < BLE and ZONAL HERB < 25%;
4) Zonal subtropical, subhumid sclerophyllous or microphyllous forest (= Subhumid Sclerophyllous Forest “ShSF”) is typified by a mutual combination of the components SCL + LEG ≥ 20% and ZONAL HERB < 30%;
5) Zonal xeric open woodland (= Open woodland) is defined by SCL + LEG ≥ 20%, ZONAL HERB = 30-40% and M-HERB > D-HERB up to a maximum of 10% of zonal herbs.
6) Zonal xeric grassland or steppe (= Xeric grassland) is defined by the proportion of ZONAL HERB ≥ 40% of all zonal taxa.
Recent studies in modern vegetation of SE China (Mt. Emei, Longqi Mt., Meili Snow Mt.) and Japan (Shirakami Sanchi, Mt. Fuji, Nara, Yokohama, Yakushima Island) that evaluated thirty-five different units of different vegetation formations generally defined as BLEF, MMF, BLDF, and ShSF, have tested and slightly corrected originally defined proportions of the important zonal woody angiosperm components, i.e., BLD, BLE, SCL+LEG components, in the defined main vegetation types (Teodoridis et al. 2011). Nonetheless, it appears appropriate to define a new vegetation formation, covering transitional vegetation (ecotone) between BLEF and MMF, and to adapt the threshold value of the BLE component for the definition of BLEF. The results obtained so far reflect also a distinct underrepresentation of zonal herbs in the fossil record regardless whether in leaf, pollen, or fruit assemblages. The vegetation scheme based on the IPR-vegetation analysis is therefore extended in order to properly reflect zonal herb diversity in modern vegetation. The results also confirm a higher diversity of zonal herbs in BLDF versus BLEF, as observed in the Neogene European record.
The modified thresholds for BLDF, MMF, BLEF and ShSF including the newly defined transitional (ecotone) vegetation types of BLDF/MMF and MMF/BLEF, and new abundance reflection of zonal herbs in modern record, are shown in table 1 presented below (Teodoridis et al. 2011, table 8). These thresholds are used for the determination of “vegetation types” for fossil and recent records in the database.
Table 1. Adapted scheme of vegetation formations including different % values of zonal herbaceous components in fossil and modern records. Modifications are based on the results of Teodoridis et al. (2011).