Geography AQA A2 Ecosystems listening notes part 2

Ecosystems at the rural urban fringe

 In these areas there are little ecological niches with its own micro climate so own types of plants which can grow.

On the rural side of the fringe there are activities such as farming and nature reserves etc. Whereas on the urban side there are a few gardens, fields derelict land etc located.

These areas can be protected as in the UK the greenbelt around major urban areas is protected from development to help reduce the amount of urban sprawl.

 

Urban ecosystems:

Introduction

Contrary to popular belief, urban

environments are not devoid of

wildlife; in fact many towns and cities

contain a greater variety of species per

unit area than equivalent areas in the

countryside. The reasons for this are:

• Urban areas contain lots of small scale,

human-made habitats, and

animals and plants have learnt to

adapt to these environments: birds

for example treat vertical walls

as cliffs and feed on discarded

human food.

• Species have been introduced both

intentionally and accidentally.

Canals, railways and roads act as

corridors for seed dispersal, and

people also transport seed on the

soles of their shoes. Seed may also

escape from warehouses, or be

brought in within topsoil.

• Unlike rural areas, urban

environments are unaffected

by agricultural sprays, and

consequently provide a refuge for

flora and fauna.

Factors influencing urban

ecosystems

Plants and animals living in urban

areas are influenced by a range of

factors:

• Soils tend to be shallow, low in

organic matter and sometimes

polluted, although those in

allotments and gardens are deeper

and more fertile.

• Large cities produce a ‘heat

island effect’ which reduces the

incidence of frost and therefore

benefits sensitive plant species.

• Air pollution in cities adversely

affects species such as lichen.

• Green spaces may be too small to

support viable plant and animal

populations.

• Proximity to seed sources and

the length and degree of human

disturbance also influence the

nature of plant and animal

compositions.

Types of urban habitats

Urban areas contain a variety of

different habitats, ranging from

relatively undisturbed patches of

woodland which have been enclosed

by development, to highly artificial

environments such as pavements and

walls .

The characteristics of some of the

more common types of urban habitat

are outlined below.

1. Derelict land

In summer, waste ground is often

covered with colourful, fast-growing,

highly productive plants such as

the butterfly bush and rosebay

willowherb. The butterfly bush

(Buddleia davidii), is a woody,

deciduous, perennial shrub which

produces lots of winged seed, easily

dispersed by the wind .

Its nectar attracts a variety of insects

and butterflies, including the red

admiral and small tortoiseshell. Its

leaves are eaten by caterpillars which

in turn are consumed by spiders

and ladybirds. The butterfly bush is

common in southern Britain, while

wetter wasteland sites in the west of

the country support giant hogweed

and Japanese knotweed. Rosebay

willowherb favours burnt sites, which

explains why it was widely seen

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