Plant Biodiversity in Urbanized Areas (PDF)

Chapter V – Challenging Urban Species Diversity: Contrasting Phylogenetic Patterns across Plant Functional Groups in Germany (S. 89-90)

1. Introduction

The high vascular plant species richness of urbanized areas in Germany is biased towards species with specific functional traits or trait states, and towards common species, as shown in the preceding chapters. The last aspect of species diversity to be analyzed here is phylogenetic diversity: In terms of species richness, an assemblage of three Poaceae species seems as diverse as an assemblage of one Poaceae, one Asteraceae and one Fagaceae species, but the former assemblage appears much less diverse when considering their phylogenetic background: The three Poaceae species belong to one family and are thus closer related to each other than the species from the three families of Poaceae, Asteraceae and Fagaceae.

Phylogenetic diversity, which measures the diversity of evolutionary relationships between species, reveals these underlying patterns, and so provides valuable information for species conservation and about mechanisms of species assembly (Vane-Wright et al. 1991). Phylogenetically closely related species often share specific traits or trait states through their common origin and evolutionary history (evolutionary niche conservatism, Harvey & Pagel 1991, Prinzing et al. 2001).

Hence, phylogenetic diversity is usually interrelated with the frequency of species per functional trait. However, phylogenetically closely related species can also develop different trait states due to adaptive radiation (e.g. Schluter 2000, Ackerly & Nyffeler 2004, Prinzing et al. 2008). In both cases, the environment influences the functional and phylogenetic structure of a species assemblage. We therefore expect differences not only in the functional but also in the phylogenetic structure of floras from urbanized and non-urbanized areas. While influences of urbanization on functional

Dr. Sonja Knapp completed her doctoral thesis at the Department of Community Ecology at the Helmholtz-Centre for Environmental Research - UFZ in Halle and at the Department of Ecology, Evolution & Diversity at Frankfurt University, Germany.