I have read the ecology of landscapes and regions written by
Dr Forman a decade ago when I was an assistant teacher to one of the world
experts in ecological landscape design, Dr. Jala Makhzoumi. The book opened for
me my horizons on what landscape ecology has to do with urban design .Although
it has never coined the terms of “Landscape Urbanism”, it definitely touches on
the founding principles of what will grow to be a mainstream urban design
paradigm.I have just gathered below the reflections gathered from the book
comparing its holistic view to the tools I have been applying in urban design
and seeing the big synergies with regional and local planning also in terms of
scale analysis and sustainability tools.
Land Mosaic change in their gradient and may be spatially
heterogeneous due to the mosaic they form. This heterogeneity is due to natural
disturbance, human activities and in some cases to substrate (below ground)
natural conditions.
FORM is The Diagram Of Force and STRUCTURE is the Function
of change _ one of the main principles on which the changes in
landscapes and regional landscapes might be explained.An interesting analysis explains further the intersections
between Urban Design and Landscape Ecology although both uses the same spatial
language, the different terminology affect the gap in communication .
Landscape Ecology – for the definition and to introduce the
subject, I will bring forward the definition that I have read in Carl Troll
book -1968)- “it is the study of the entire cause effect network between the
living communities and their environmental conditions which prevails in a
specific section of the landscape and become apparent in a specific landscape
pattern or in a natural space classification of different orders”’ .
Another
interesting definition for landscape ecology stems from the research conducted
in 1984 by Paul Risser .He speaks of Landscape Ecology in terms of its focus
rather its activities . Landscape Ecology considers the development and
dynamics of spatial heterogeneity wether it is the spatial and temporal
interactions and exchanges across heterogeneous landscapes, the impact of the
spatial heterogeneity on biotic and abiotic processes as well as the management
of spatial heterogeneity.
Landscape Ecology uses the Patch ,Corridor, Matrix to
differentiate between the different landscape types and regional territories.
Urban Design uses District, Edge, Path to study the different urban and rural
fabrics. The variations of the different territories (whether it is a natural
landscape or urban fabric) are attributed to the same factors – Movements
(transport or fauna), Patterns(Organic versus Manmade),Scale( regional versus
local). The granularity is affected by Time - the responses of the landscape or the fabric
through TIME might lead to Fine or Coarse fabric or landscape pattern.
Miller(1978) has set the different domains in scale when it
comes to define the landscapes in which intervention is needed:
Continents /They are characterized by distinct boundaries usually surrounded
by water surfaces .Culture, Economics and Transportation connectivity make up
for their uniqueness.
Regions/Broad geographical area with a common microclimate and
unified sphere of human activity and interest – physical factors such as the
macroclimate, soil groups and bioms and human factors such as politics, social
groupings, structure, culture contribute to their emergence.
Landscape /Mosaic formed by the mix of local ecosystems – it is an
ecological unit that may be formed by a repeated cluster of spatial elements –
the essential elements of landscapes can be analysed through :
1-
Geological land forms
2-
Soil types
3-
Vegetation types
4-
Local fauna
5-
Natural disturbance regimes
such as fire
6-
Land uses
7-
Human aggregation patterns
which is the domain in which regional urban planning engages at
The ecology of regions – regions are usually the scale at
which one single macroclimate prevails providing a region wide control over
soils, ecosystems and natural processes. A region is the scale at which
sustainability can be better pursued for its larger area that may cover many
landscape types, its greater adequacy for ensuring resources complementarity
and slower rate of change.
Patches are synonyms to boundaries –Patches affect the rates
of flows and movements between ecosystems – flows and movements are defined
through the array of objects they transfer be it wind carrying air, rivers with
water streams ,animals , birds, airplanes carrying passengers or just a couple
of neighbors walking a marathon. These six vectors can be flowing in locomotion
– slow motion or in mass flow- rapid motion. Usually, mass flow crosses over
external boundaries such as TGV crossing over and locomotion are for internal
movements such as local breeze. Permeability – same term used in urban design-
is linked to how diverse the flows are and how the density of these flows is
building up.The flows crossing over the boundaries of the different
patches relate to four main ecological processes Supply to Patch, Resistance of
Patch, Retention by Patch, Disposal from Patch.
Corridors have been analyzed extensively especially relating
to Rivers and Streams _ the analysis will be summarized later in another Blog
Post.What I would like to focus on is some of the tools that were presented and
which might be useful to reflect on in thinking about our cities as man-made
ecosystems. The first spatial tools which are used to approach the territory
under study is land use optimization focusing on agricultural
production,natural ressources areas as
well as corridors and greenways.
A generic plan might take into consideration some of the
priniciples highlighted below:
1-
Context – placing the
landscape/corridor/fabric in its regional/continental scale
2-
Flows- evaluating the flows
and movements of ground /surface water ,species dispersal, transportation, recreation
3-
Change- looking for changes
in the natural environment such as spreading desertification, housing growth, new
infrastructure ,water barriers such as damns
4-
Disturbance regimes-
Hurricanes, flood, cyclones are repetitive natural phenomena that might affect
the future projections and proposed interventions
Another interesting concept that is linked to Landscape
Ecology work in the 1990’s is the concept of Whole /Holisitic landscapes. Dr
Makhzoumi has written a reference book on landscape ecological design and how
its approach can be applied on place making and other urban design spatial
interventions.
The concept of whole landscapes apply more to regional
scale.it sets again a number of principles if followed can contribute to a more
holistic approach to framework planning – the holistic approach comes from
integrating the human made environment’s and the natural environment’s in a way
that does take into consideration high sensitivity topics for human activity
but does not jeopardize the livability of other flora ,fauna species . it calls
on identifying and maintaining natural expansion corridors, assigning biodiversity
areas , taking into consideration
natural disturbances phenomena and respecting connectivity, permeability and
the granular scale of the landscape mosaic focusing on landscape linkages
I would like to end this post with an interesting statement
by Carra made in 1990 .His answer to the ways in which we can integrate human and natural habitat was:’Only
if we view the world differently , we would be able to act differently. So, we
need a change of perception, a shift of paradigm in our thinking and in our values.
We need a shift from fragmentation to wholeness, from a mechanistic view of the
world to an ecological view, from domination to partnership, from expansion to
conservation, from efficiency to sustainability”. His answer encapsulated most
of the different dimensions that planners, designers, policy makers and
citizens deal with in their own way and the direction we all need to take in
order to make sure that the aspirations of our cities and towns do not lead to
their own destruction.
