BASIC TRENDS IN ECOGEOGRAPHIC DIFFERENTIATION

     Like numerous species represented by their local populations, regional flora forms on a given territory in definite natural and historical conditions to present a system of species that have adapted as a result of lengthy interdependent development to combined growth to maximally correspond to the natural and climatic conditions of the given area.
At the same time, the heterogeneity of the physical geographic conditions of the area on which the flora develops would determine its ecogeographical differentiation into sets of species corresponding to a combination of major environmental and landscape factors typical of the given territory.
 Seven basic floristic complexes of indigenous flora (Kozhevnikov, 2995; Kozhevnikov, 1997) are represented in the Russian Far East. They combine species that in respect to ecocenotic features and distribution nature tend to natural territorial complexes (landscapes) with homogeneous botanical and geographical properties.
 The principal natural territorial complexes (landscapes) in Primorye involve forests, steppes, meadow-flood plains (valleys and meadows) arcto montane and meadow-littoral  floristic (landscape-geographical) complexes.
 Species of the forest floristic complex are widespread in Primorye, but are most abundantly and diversely developed in the foothills and central belt of the Sikhote Alin mountain range. They form two ecogeographical groups, namely the dark conifer forest group preferentially associated with alpine spruce-fur and fur forests comprising Abies nephrolepis (Trautv.) Maxim and Picea ajanensis (Lindll et Gord.) Fisch ex Carr, with cedar-broadleaved species (P. koraiensis, Abies holophylla Maxim., Fraxinus mandshurica Rupr., Ulmus laciniata (Trautv.) Mayr, Carpinus cordata Blume, Acer tegmentosum Maxim., Actinidia arguta (Siebold et Zucc.) Planch., A. kolomicta Maxim., Plagiorhegma dubia Maxim.) and with broadleaved species  (Fraxinus  rhynchophylla Hance, Juglans mandshurica Maxim., Phellodendron amurense Rupr., Quercus mongolica Fisch. ex Ledeb., Tilia amurensis Rupr., Ulmus japonica (Rehd.) Sarg., Maackia amurensis Rupr. et Maxim., Schisandra chinensis (Turcz.) Baill., Asarum sieboldii Miq., Chloranthus japonicus Siebold from deciduous forests.
    The steppe floristic complex is represented in Primorye preferentially by the forest-steppe ecogeographical group, whose species are chiefly widespread within the bounds of Suifun-Hanka Plain. The following species are characteristic representatives of this complex here: Carex ulobasis V. Krecz., Clematis hexapetala Pall., Cleistogenes kitagawae Honda, Dioscorea nipponica Makino, Lilium cernuum Kom., L.pumilum Delile, Platycodon grandiflorus (Jacq.) A.DC., Scutellaria baicalensis Georgi and others.
    Species from the meadow-flood plain floristic complex are assigned to water reservoirs, flood plains and river valleys, where they form the water, water-bog, river-bed and meadow (flood plain-meadow) ecogeographical groups. In Primorye, this complex is represented quite abundantly and diversely to include a number of families, all of whose representatives are associated exclusively with water and coastal-water habitats. Representatives of the families Isotaceae, Cabombaceae, Nymphaeceae (Numpheae tetragona Georgi), Ceratophyllaceae, Nelumbonaceae, Elatinaceae, Trapaceae, Haloragaceae, Callitrichaceae, Hippuridaceae, Lentibulariaceae, Butomaceae, Lemnaceaea; many representatives of the families Cyperaceae, Juncacaceae, Sparganiaceae, Ranunculaceae, Poacae and others are also quite typical of this complex. Most of them grow in association with Ussuri River basin, chiefly with its valley and the bogged areas of Hanka Depression.
 The meadow-littoral complex includes species, whose distribution and development is associated with specific conditions of seacoasts, and is represented by littoral-water, littoral-meadow, supralittoral-meadow, seacoast-meadow and seacoast rock-loving ecogrographic groups. The minimal concentration of species from this floristic complex is observed on the southern and southeastern coasts of Primorye. A number of specific families, whose representatives grow exclusively along seacoasts (Ruppiacae, Zanniichelliaceae, Zosteraceae, and Najadaceae) also belong to this complex. Besides, it is also typified by numerous species from the families Asteraceae, Poaceae, Cyperaceae, Rosaceae, Fabaceae, etc.
 Species from the arctomontane floristic complex are developed preferentially on Sikhote Alin highlands, specifically the Alpine, Arctic-Alpine, and Hyparctomontane ecogeographical groups, and partly in the forest belt the montane group represented by Rhododendron aureum Georgi.

  A. KOZHEVNIKOV, Cand. Sci. (Biology), Head, Department of Botany, Institute of Biology and Soil Science, Russian Academy of Sciences.

Illustrations by Z. Kozhevnikova.

E-mail: botany@ibss.marine.su
  
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