Terrestrial Palaeoecology and Global Change

166 Valentin A. Krassilov. Terrestrial Palaeoecology
Sedimentary basins involved in orogenic uplift and subsequent denudation, might leave
no traces other than redeposited palynomorphs (e.g., the reworked Carboniferous palynomorphs
in the areas devoid of Carboniferous deposists: Guy-Ohlson et al., 1987).
Likewise, redeposited palynomorphs provide a timing of orogenic uplift of the source
areas (e.g., of the Rocky Mountains exhumation from under the Palaeogene peneplain,
with the reworked palynomorphs reaching to the Gulf of Mexico).
A chronology of orogenic uplifts can also be deduced from the dynamics of altitudinal
vegetation belts (Axelrod, 1965, 1997) and a spread of xeromorphic vegetation in the
rain shadows, as over the piedmonts of incipient Rocky Mountains in the Late Eocene
(Axelrod & Raven, 1985).
Thus, both latitudinal and altitudinal differentiation of fossil plant assemblages provide
evidence of tectonic reconstructions. Globally, the vegetational zonation reflects a heat transfer
controlled by geography in turn controlled by tectonics. Mountain ranges form boundaries
of vegetation types, as in the case of the broadleaved/pine forest types divided by the Urals.
Similarly, the Angarian and Cathaysian taphofloras in Primorye and Japan were separated by
the Vladivostok – Abo system of volcanic ranges (Krassilov, 1972a). As the relationships of
the Laurasian and Gondwanic floras suggest, orographic barriers for floristic exchange over
the Tethys belt might have been more efficient than marine barriers.
Tectonic developments also indirectly affect phytogeography by their impact on climate.
Thus, a distinctness of zonal vegetation boundaries increases with a restriction of
the meridional heat transfer by latitudinal mountain ranges. Sea-floor uplifts might have
a similar effect by restricting deep-water circulation inflicting a monsoon depression and
xeromorphism of equatorial vegetation. Conversely, a spread of equatorial rainforests is
owing to summer monsoons that are sustained by the tropical upwellings of psychrospheric
oceanic circulation in turn related to a subsidence of land barriers and a free
passage of deep water through marine gateways.
V.9.1. Tectonics and vegetation of continental margins
A tectonic zonation of active continental margins with the coastal volcanic ranges,
their foredeeps, island arcs and forearc basins is reflected in the pattern of vegetation
zones and taphonomic environments. Changes of the latter are evidence of tectonic
restructuring. In the Sea of Japan example (Krassilov, 1975b), differentiation of plant
communities reflects both the scale and timing of tectonic events.
A vegetational zonation over Japan Islands (Kimura, 2000 and previous work) is traceable
to the maritime area of Primorye (Krassilov, 1967a). About one third of Neocomian
species are distinctive for the inner (Tetori) zone of Japan as compared with the roughly
contemporaneous outer (Rioseki) zone. On account of bennettite diversities, including several
Dictyozamites morphotypes, the Tetori flora appears more thermophilic of the two.
Since their dividing “median line” is a shear fault zone, the vegetational differences might