Title: TREES
1TREES IN HABITAT AS HABITAT
- Issues, considerations, suggestions
2Contents
- Tree habitats
- Trees as habitat
- Management considerations and options
Marble Hill Park, London
3Aims
- To examine the factors which should inform any
prescription for tree management - To suggest outline guidance for determining
management objectives and implementation
Marble Hill Park, London
4Tree habitats
- Trees grow in different habitats. It is
important to recognise this as the place where a
tree is growing will have a major influence on
its future management. Tree habitats divide into
two main groupings - Urban i.e. built-up, developed areas
- Rural areas
5Urban areas - towns and cities
- Highways and transport infrastructure areas
- Housing areas
- Parks and gardens
- Commercial and industrial areas
- Schools
- Settings for historic buildings
Champs Elysee, Arc de Triomphe, Paris, 1944
6Urban areas bring man and tree into closest
conflict (1)
- Safety
- Need for management increases with intensity and
sensitivity of site use (e.g. childrens
playgrounds) - Will increase with age of tree
- Will increase according to past tree management
(e.g. pollarding) - Interference with services
- Overhead
- Underground
- Highways - sight-lines, sign clearance, street
lights
Champs Elysee, Arc de Triomphe, Paris, 2005
7Failed Aesculus hippocastanum
High Wycombe, Buckinghamshire, England
8Failed Aesculus hippocastanum
- Tree growing adjacent to a public car park
- Inspected a few weeks earlier by contractor who
failed to realise urgency of need for work - Embedded branch junction failed, damaging car and
injuring driver - Tree owner completely at fault
High Wycombe
9Urban areas - conflicts (2)
- Inhospitable growing conditions
- Soils
- Pollution air, water
- Mechanical damage
- Poor management/lack of management
- Management costs
- Difficulties of managing a large and changing
resource, some of which is not in public control
La Defence, Paris
10Urban areas - conflicts (3)
- Pressure for more space development
- Above and below ground pressures
- One tree may be a habitat in itself, rather than
forming part of a grouping
Notting Hill, London
11The urban situation
- Managed trees
- High maintenance input
- Multiple problems
- Historic considerations
12Trees in urban areas are often the most highly
prized
- They soften the built environment
- They add relevance to development
- They provide visual links between differing
landscape types and uses - They provide a scale to which humans can relate
- They contribute to a sense of place
- They influence local micro-climate
Nottingham, England
13Urban areas - clear conflict
- Highly prized trees
- In areas where they are under pressure
- HOLD THIS THOUGHT!!!!!
14Rural areas tree habitats
- Forests (economic)
- Woodlands (amenity and multi-use)
- Farmland
- Hedgerows
- Transport systems
- Roads
- Rail
- Waterways
Suffolk, England
15Rural areas
- Pressures on trees generally less severe
- Land use for people less intensive
- Environmental conditions usually less degraded
- Trees can form part of a habitat grouping, rather
than being the sole habitat - THE INDIVIDUAL TREE MAY BECOME LESS IMPORTANT
16Tree habitats - summary
- Urban areas
- fewer trees, each individually prized for its
landscape, social and wildlife conservation
values - need to maintain trees in a safer condition
- greater potential for conflict
- Rural areas-
- more trees, each less valuable individually
- safety parameters expanded
- value as part of a grouping rather than as
individuals
17Trees as habitat
- A tree may be regarded as a large volume of
greenspace held conveniently above head level.
It has the potential to contain a number of
varied (and in some cases, rare, habitat types). - Leaves
- Fruit
- Buds
- Flowers
- New growth
- Bark
- Conducting tissue
- Rooting zone
- Cast detritus
- DEAD WOOD
18Trees as habitat
- Trees have a number of features which make them
particularly valuable as habitat
- They live to considerable age
- They achieve very large sizes
- They have a large surface area to volume ratio
- They offer a range of differing shelter and food
sites - These change
19Trees change..as they age, they provide
different, specialised habitat sites
- Holes in branches
- Cavities,
- Dead wood
- Crevices in bark
- Fungal fruiting bodies
- Water pools
- Sites for ephiphytic plants
- Loose bark
- Cast dead wood
- Sap runs
Photo Roy Finch
20Burnham Beeches, Buckinghamshire, England. Photo
Roy Finch
21Old, apparently dilapidated trees are very
valuable in wildlife terms
- An important feature is the presence of dead or
dying wood this provides the habitat for some
very specialised invertbrates which cannot
survive elsewhere they are called saproxylic
organisms. Some species of beetle are
particularly important and are threatened because
of the absence of dead wood.
22We are now faced with a dilemma (1)
- Man requires that trees are kept
- Safe
- In pleasing aesthetic condition
- That landscape features such as avenues are
maintained - That infrastructures work
- That risk of disease insect colonisation is
minimised - That everything is TIDY!!!!!
23We are now faced with a dilemma (2)
- Wildlife conservation (biodiversity) and the
conservation of many threatened species requires - That we allow things to decay and become
potentially dangerous - That we leave untidy detritus
- POSSIBLY, that we CREATE conditions for
colonisation by organisms - WE HAVE CONFLICT !!!!!!
24Dangerous branches over house
SE, 2006, photo De Gouret
25Suspect, dead pollard close to railway line (DG)
SE, 2006, photo De Gouret
26Stumps in conifer plantation SE responsible for
infestation of bark beetle in standing crop (DG)
SE, 2006, photo De Gouret
27Creating old trees (1)
- There is a current trend towards creating
habitat niches in healthy trees which would
otherwise not be there until they aged. This can
be done by deliberate injury - Spiking live trunks
- Deliberate tearing of branches when pruning
- Creating pollards from established trees
28Creating old trees (2)
- This may be justified BUT we must consider the
situation - Aesthetics
- Landscape
- Historical implications
- Safety
- Position
- Liability
29Photo DG, 2006
30Creating old trees (3)
- Will the process be effective?
- Will the protected organisms colonise the tree?
- Use of native species
- Is the protected species sufficiently threatened?
- Will the wrong species colonise the tree
- Is there a risk that diseases or pests will
proliferate? - Ethics
- is it right to damage a healthy organism?
- Is it right to shorten the life of a tree which
might give pleasure to future generations?
31Need for an assessment methodology
- Unconsidered retention or creation of dangerous
trees is irresponsible - There is a clear need for specialised habitats
for the protection of endangered species - A methodology for assessment should consider
- The tree
- The landscape
- The people
- The wildlife
32THE END
- Thanks for your attention