Transcript Slide 1

Landscape ecology methods
An overview of a few of the
methods used in landscape
ecology studies
UBC Geography 471
Commonly used methods
• Some of the more commonly used
methods include:
– Markov analysis
– Simulation models
– Spatially-explicit population models
– New indices
Markov analysis
• Markov chain
A random process in which the probability
that a certain future state will occur
depends only on the present or
immediately preceding state of the system,
and not on the events leading up to the
present state.
Integrating landscape Models in Forest
landscape Analyses using GIS: An Example in
Taiwan
The transition matrix and transition probabilities of the observed landscape changes from 1988 to 1996
Transition from row to
column
Man-made
conifers
Man-made
hardwoods
Mixed
forests
Natural
hardwoods
Bare
lands
Cut
areas
1996
total
Man-made conifers
384.3
0.841
3.1
0.007
13.6
0.036
50.6
0.111
5.4
0.012
0
0
457.0
1
Man-made hardwoods
1.5
0.017
48.3
0.563
1.4
0.016
34.6
0.403
0
0
0
0
85.7
1
Mixed forest
2.5
0.121
0.4
0.019
13.4
0.008
4.3
0.208
0.02
0.001
0
0
20.6
1
Natural hardwoods
35.1
0.119
60.9
0.034
13.97
0.008
1688.0
0.936
4.1
0.002
1.58
0.001
1803.7
1
Bare lands
1.0
0.051
0
0
0
0
13.7
0.727
4.2
0.222
0
0
18.9
1
Cut areas
12.25
0.248
14.65
0.297
10.4
0.211
11.7
0.237
0.4
0.007
0
0
49.4
1
1988 total
436.6
127.4
52.7
1802.9
14.1
1.6
2435.3
http://www.gisdevelopment.net/aars/acrs/1999/ps1/ps1729.asp
Simulation models
• A computer simulation or a computer model is a
computer program that attempts to simulate an abstract
model of a particular system. Computer simulations have
become a useful part of mathematical modeling of many
natural systems in physics, chemistry and biology,
human systems in economics, psychology, and social
science, and in the process of engineering new
technology, to gain insight into the operation of those
systems.
• Traditionally, the formal modeling of systems has been
via a mathematical model, which attempts to find
analytical solutions to problems which enables the
prediction of the behaviour of the system from a set of
parameters and initial conditions.
Simulation models: Harvest
• HARVEST was designed as a strategic research
and planning tool, allowing assessment of the
spatial pattern consequences of broad timber
management strategies. The model is well
suited to evaluate alternative strategies,
providing comparable predictions about how the
alternatives affect the age (or successional
stage) distribution of the forest, the spatial
distribution of forest interior and edge habitats,
and the patch structure of the resulting forest
landscape.
Harvest
With HARVEST, the object is not to find a scheduling solution
(i.e., determining the order in which individual stands should
be harvested), but to assess the spatial pattern consequences
of general management strategies. HARVEST has been shown
to generate patterns similar to those produced by timber
management (Gustafson and Crow 1999).
http://www.ncrs.fs.fed.us/4153/Harvest/v60/v6_0.htm
SPATIALLY EXPLICIT
POPULATION MODELS
• Spatially explicit models have a structure that specifies the location
of each object of interest (organism, population, habitat patch) within
a heterogeneous landscape, and therefore the spatial relationships
between habitat patches and other features of the landscape (e.g.,
landscape boundaries, corridors, other patches) must be defined.
• Since the spatial layout of the landscape is explicitly incorporated,
the models can be used to indicate how populations or communities
might be affected by changes in landscape structure, including
changes in landscape composition (the relative or absolute amount
of habitat types or features in a landscape) or landscape
physiognomy (the exact placement of habitat patches and other
features within the landscape) (Dunning et al. 1992).
Northern Spotted Owl
• Perhaps the most common use of SEPMs to
date has been in the study of individual and
population response to landscape change.
• How do the risks to persistence of the owl
population vary among five alternative logging
schemes during the transitional period? Do
some alternatives have unacceptably high risks
of crossing a habitat threshold, beyond which
the population declines inescapably to
extinction?
Northern Spotted Owl
• Questions such as these can be addressed only by
considering the amount, geometry, and rate of change of
habitat in a spatially and temporally explicit fashion. The
transient behavior of the Spotted Owl population in
Oregon is being examined using OWL, a SEPM
integrated with a GIS database of the forested landscape
in Oregon (McKelvey et al. 1992, Turner et al. 1995).
• Preliminary studies indicate that whatever management
strategies are selected will significantly affect the
population trajectory during the transition until the final
reserve design is reached.
Northern Spotted Owl
•
Projected change in the amount of
Spotted Owl habitat on National
Forests for five alternative
strategies (numbered solid lines)
that establish a Spotted Owl
reserve design in the Pacific
Northwest (USDA 1992). The
dashed line indicates the current
amount of owl habitat. Note that
alternatives 3-5 project a
continuing loss of habitat during
part or all of the simulated time
span. This loss occurs even
though the owl is currently listed
as threatened due to past loss and
fragmentation of its habitat (USDI
1992).
http://www.szooek.slu.se/~EcoForest/Block3/dunn95.html
Landuse change in Dublin
This index (Green Edge)
shows how much
of a region’s urban fabric is
adjacent to (i.e. has an edge with)
vegetated areas. Areas with
a high value for the index will have
greater access to recreational
facilities (e.g. gardens, parks,
wooded areas, sports fields),
and will be less affected by noise
and air pollution from traffic.
Nature-deficit disorder
http://moland.jrc.it/technical_tools/frag/moland_fra.htm
Explore
• These are a few of the different methods
that are used in landscape ecology (and in
crime analysis and medical geography as
well).
• In the papers you review you are likely to
come across other methods—the ability to
map the results of analyses has added
considerably to the utility of many methods.