Testing basic assumptions of species richness hypotheses using plant species distribution data

The earth's species richness is the result of biological evolution over the last billions of years. Manifold processes interact together and influence the spatial distribution of species richness. Trying to answer the question of "why are there so many kinds of species", researchers developed countless species richness hypotheses over the last two centuries. Different mechanisms influencing species richness patterns act on different spatial and temporal scales. As in natural systems space and diversity are correlated, it is diffcult to disentangle the manifold factors, which are correlated either as a consequence of mechanistic relationships, or as a matter of stochasticity. In the present thesis we tested the following aspects of plant species diversity:

1. Climate gradients and species richness of functional groups (Chapter 2)
2. Habitat diversity and area effect on species richness (Chapter 3)
3. Climate gradients and historical effects on species richness (Chapter 4)