A factor analysis approach to modelling the early diversification of terrestrial vegetation
Abstract Data from a new comprehensive macrofossil-based compilation of early plant genera are analyzed via a Q-mode factor analysis. This compilation ranges from the Silurian to the earliest Carboniferous and illustrates the key vegetation changes that took place during the configuration of early terrestrial ecosystems. Results reveal that four factors can be used to explain more than 90% of the variance in the data. These factors are interpreted as the major phases of the early land plant evolution: a first Eotracheophytic flora (Silurian-Lochkovian) dominated by basal eutracheophytes and rhyniophytoids, an early Eophytic Flora (Early Devonian) dominated by zosterophylls, a transitional late Eophytic Flora (Middle Devonian-earliest Carboniferous) dominated by lycopsids and cladoxylopsids, and finally, the earliest phase of the Palaeophytic Flora (Late Devonian-earliest Carboniferous) dominated by the first seed plants. These floras present different but complementary diversity patterns, which help us to understand the overall trajectory of changes in plant diversity. Results further show how the maximum peaks of diversity appear linked to the rise of each new flora but, interestingly, these diversifications are not associated with any exponential declines of the previously dominant one. This new four-phase diversification model reflects the early steps of Earth's greening.