The ecology of urban areas and their functions for species diversity

Abstract

Despite the appearance of an enormous number of publications about urban ecology and species diversity, many issues are simply opened up rather than explained. The ecological complexity of urban areas, i.e., the variety of determinants and the spatial and temporal dynamic of cities, preclude simple starting points and lines of explanation. Therefore, we lack sufficient comparisons between various cities, especially comparisons on a global level. If cities are to be compared by appropriate indicators, and if they are to be evaluated with respect to urban biodiversity, then models are necessary that help us understand and mirror the causal relationships between urban areas and biological diversity. Three approaches, also representing a multiscaled view of urban areas, are presented that are suitable for developing applicable models and indicators for monitoring ecological systems: the embedded city, the urban matrix, and urban patches. The embedded city represents a globally useful concept, because the relationship between cities and their regions can be applied as an indicator to all regions. The lack of sufficient description of the urban matrix makes comparisons between cities difficult and causes scientists to underestimate the importance and function of the matrix for urban biodiversity. Urban patches are often investigated in urban studies about plants and animals. Therefore, much existing data can be used, and several criteria describing the functions of patches for biodiversity are available. In particular, the first two approaches should be researched more intensively.

Urban biodiversity hotspots wait to get discovered: The example of the city of Ioannina, NW Greece

“…This is not a generalized scheme among urban ecosystems (see Ricotta, Godefroid, & Rocchini, 2010), but applies to the Mediterranean ones. In any case, urban florae are primarily part of the regional pools of species (Kühn, Brandl, & Klotz, 2004;Werner, 2011;Williams et al, 2009). In Germany, Kühn et al (2004) showed that cities established in areas of high geological diversity and in preexisting biodiversity hotspots show high plant diversity as well.…”

“…In Mediterranean cities (Table 5), aliens' representation is generally much lower than in Central and Northern Europe because of the highly competitive native stock, which has adapted to the intense and long-standing anthropogenic disturbance (Pignatti, 1983;Werner, 2011). Aliens in Greece account only for ca.…”

Ecological Characteristics of Two Closely Related Rodent Species in Urban Environment—Permanent Inhabitant vs Newcomer

“…Urban habitats differ from natural, non-urban habitats in numerous ways [3]. Cities are characterized by transformed abiotic conditions, high levels of light and noise, pollution of the soil, water and air, a milder climate, later arrival of winter and earlier arrival of spring, elevated temperatures due to a high heat capacity of anthropogenic surfaces, a lower diurnal and seasonal variation in temperature, etc.…”

“…Cities are characterized by transformed abiotic conditions, high levels of light and noise, pollution of the soil, water and air, a milder climate, later arrival of winter and earlier arrival of spring, elevated temperatures due to a high heat capacity of anthropogenic surfaces, a lower diurnal and seasonal variation in temperature, etc. [3]. Cities also offer a high availability of anthropogenic food, which-in combination with the milder climate-allows many species to extend their breeding season [4].…”

“…Green areas within cities are highly heterogeneous [3], comprising numerous patches of varying size and quality, interspersed by regions with a high density of buildings and busy transport routes. This leads to the formation of numerous highly isolated microenvironments [5].…”