Geoscience Reference
In-Depth Information
(
a
)
(
b
)
Fig. 1. (a) Simplified phylogenetic tree of the Palaeozoic vascular land plants modified from Kenrick & Crane
(1996). Derived traits in relation to the tree habit in italics. Stratigraphic extent of trees in black. Ages in millions of
years, after the Internal Commission on Stratigraphy (http://www.stratigraphy.org/cheu.pdf ). (b) Evolution of
maximum axis diameter in the Devonian, modified from Chaloner & Sheerin (1979). Small black circles:
non-arborescent plants; light grey circles: Lycopsida; grey squares: Cladoxylopsida; star: Equisetopsida; dark grey
triangles: Archaeopteridales.
it is uncertain whether lignolytic organisms had
evolved before the end of the Devonian (Stubble-
field et al. 1985; Robinson 1996). The Beerling-
Berner model also identifies processes linking
the extension of the root system to plant size and
canopy size to leaf size that are pivotal for their
effects on CO
2
and on climate parameters such as
rainfall and temperature.
