They may contain more than a single plant formation (dominant vegetation of similar structure) and hence more than one biome (animals plus plants determined by vegetation structure), so it is important to utilize these smaller landscape units when discussing transitional biogeography.
These were a) percentages of eastern and western species among the reptiles, birds, and mammals, six variables per county; b) percentages of each plant formation plus the eastern and western range-limited species, five variables per county; and c) percentages of each plant formation and vertebrates per plant association, six variables per county.
2) Which plant formation is most influential in limiting species?
The analysis employing plant formation and range limits data reveals a more complex landscape pattern (Fig.
1990) and not whole landscapes, I shall provide a broader quantitative study of distributional patterns, employing plant formations and all classes of terrestrial vertebrates.
This region was chosen, because it is a representative cross-section of the three major plant formations in central Texas--deciduous forest, tallgrass prairie, and evergreen woodland from east to west (Fig.
Extent of the three plant formations in each county was calculated with a plainmeter, using maps by Beaty and Gehlbach (1975) and McMahan et al.
1) and contain the most similar proportions of all three plant formations (Table 2).
A limited concordance of vertebrate assemblages and plant formations is shown in the third analysis (Fig.