Approaches to urban ecosystems

Question 1

Why are there more native AND introduced species in urban areas than in rural areas?

Answer 1

• city effects (city/non-city) especially important for alien species
• location of many cities in geologically diverse situations important for native species
• high heterogeneity of urban habitats, important for alien and native species

Question 2

With increasing number of inhabitants in a city, the number of species increases too. Why?

Answer 2

species - area relationship: larger areas tend to harbor more species (increasing diversity of ecological niches, human agency.. )

Question 3

Where do you find rare species in cities?

Answer 3

hotspots at the urban fringe

Question 4

Where do you find nonnative species in cities?

Answer 4

hotspots in urban core

Question 5

definition of biotope

Answer 5

• a place with similar environmental conditions, where assemblages of plants or / and animals exist
• a biotope may but must not have a conservation value

Question 6

Patch attributes

Answer 6

• minimum area for individuals / populations
• compactness (relation of edge versus core areas), important as buffer against disturbances
• isolation of patches, may decrease colonization processes
• habitat heterogeneity of connected patches, important for species with different habitat requirements

Question 7

Why does the urban matrix matter?

Answer 7

• ecologically relevant impacts from surroundings (e.g. nutrient influx, urban heat island effects, recreation pressure, escape of species from gardens, …)
• potential barriers or corridors for dispersal of plants and animals

Information about matrix effects support green networks

Question 8

Urban biotopes as spatial units -> patches,

short definition?

Answer 8

A patch is a relatively homogeneous area that differs from its surroundings

Question 9

Why does the historical dimension (e.g. habitat age) matter for species occurrence / richness?

Answer 9

• habitat age: time-dependent development of ecosystem characteristics (species immigration, soil development, vegetation development (succession))
• land use-legacies: remnant species assemblages, history of connection/fragmentation

Question 10

Why are there differences between ancient and recent habitats?

Answer 10

• traditional species pool in ancient habitats
• missing species in recent habitats (isolation due to dispersal limitation)

-> important issue for urban development

Question 11

Why are species numbers in cities increasing while these numbers are decreasing in surrounding areas?

Answer 11

• intensified agriculture increases habitat function of agricultural fields
• increasing development of biodiv. in cities
  (high number of ornamental species planted; can become component of wild flora)

Question 12

One introduced specie from Asia (eastern) in Central Europe

Answer 12

Empress tree (Paulownia tomentosa)