Proceedings of the California Academy of Sciences
Terrestrial ecosystems of the late Paleozoic form a distinct global hierarchy of organizational levels, paralleling that seen in the modern world. At the highest level are at least three biotic provinces delimited by geographic and very broad scale climatic factors. Within each province are several biomes, reflecting substrate and climatic controls. Biomes are roughly equivalent to plant “species pools,” those plants capable of colonizing available resource spaces within the physical area of the biome, and within which many species are roughly ecologically equivalent. Biome boundaries tend to be rather sharp. Within biomes are recurrent species associations, or communities, among which there is significant overlap in composition but that differ in dominance-diversity patterns. These patterns are examined here primarily in ancient tropical systems. The patterns of spatial partitioning of Permo-Carboniferous landscapes conform broadly to those predicted by the unified neutral theory of Hubbell (2001). However, species ecological equivalence is not “global” but rather appears to be restricted to biomes/species pools. The complexity of this hierarchical organization appears to have increased and deepened from the time vascular plants appeared on the land surface in the Late Silurian through the late Paleozoic and beyond. This may be related, in part, to increased “energy” input into the system, driving spontaneous organization of complexity and progressively restricting the spatial scale of species equivalence.
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