Graphes paysagers- Xavier Girardet

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Transcript of Graphes paysagers- Xavier Girardet

  • Xavier Girardet

    Laboratoire ThMA UMR 6049

    UBFC / CNRS

    Besanon

    Modl i sat ion des rseaux

    cologiques en cologie

    du paysage :

    l es graphes paysagers

    Sminaire Atelier 8 /

    ISIG, Graphes et

    rseaux en gographie

  • De la mise sous cloche.. aux rseaux cologiques

    20001900 2010

  • De la mise sous cloche.. aux rseaux cologiques

    Lmergence dune discipline

    20001900 2010

    1970 1980 1990

  • De la mise sous cloche.. aux rseaux cologiques

    Lmergence dune discipline

    Les graphes paysagers

    20001900 2010

    1970 1980 1990

    2001 2006 2008 2012

  • From landscape structures to landscape networks

    Artistic movement: focus on the nature

    Protection of aesthetics landscape

    1. De la mise sous cloche.. aux rseaux cologiques

  • From landscape structures to landscape networks

    Protection of spectacular landscape

    1. De la mise sous cloche.. aux rseaux cologiques

  • From landscape structures to landscape networks

    Protection of flora and fauna

    In 1995, Germany had

    5,314 nature reserves

    1. De la mise sous cloche.. aux rseaux cologiques

  • From landscape structures to landscape networks

    Protection of flora and fauna

    1. De la mise sous cloche.. aux rseaux cologiques

  • From landscape structures to landscape networks

    Networks of ecosystems

    1. De la mise sous cloche.. aux rseaux cologiques

  • From landscape structures to landscape networks

    Ecological networks

    1. De la mise sous cloche.. aux rseaux cologiques

  • From landscape structures to landscape networks

    Ecological networks

    1. De la mise sous cloche.. aux rseaux cologiques

  • From landscape structures to landscape networks

    - Ecological networks- Landscape connectivity

    Structural connectivity Functional connectivity

    Landscape networks

    1. De la mise sous cloche.. aux rseaux cologiques

  • What is landscape ecology ?

    LandscapeEcology

    Broad Extents

    K. McGarigal

    2. Lmergence dune discipline

  • What is landscape ecology ?

    3 fundamental principles

    1. The effect of spatial heterogeneity on ecological processes

    2. The role of humans

    3. A broad spatial scale: the landscape

    2. Lmergence dune discipline

  • The effect of spatial heterogeneity on ecological processes

    MacArthur & Wilson (1967): The Theory of Island Biogeography

    2. Lmergence dune discipline

  • The effect of spatial heterogeneity on ecological processes

    Forman & Godron (1986) : Landscape mosaic model

    2. Lmergence dune discipline

  • The effect of spatial heterogeneity on ecological processes

    Metapopulation models: the first step to landscape connectivity

    2. Lmergence dune discipline

  • The role of humans

    Forman (1995): Landscape fragmentation

    2. Lmergence dune discipline

  • A broad spatial scale: the landscape

    Delcourt & Delcourt (1988) and Allen & Starr (1988):The hierarchical theory. Space and time are linked !

    2. Lmergence dune discipline

  • What is a landscape graph ?

    Function

    Reality

    Model

    3. Les graphes paysagers

  • 3. Landscape graphs : origins

  • 3. Landscape graphs : the sequel

  • 3. Landscape graphs : the prequel

  • 3. Intgration dans les scenarios de gestion et damnagement

  • Construction des graphes paysagers

    Construction

    des graphes

    paysagers

  • Graph construction: identification of habitat patches and links

    Landscape map

    Suitable elements Barrier elementsOptimal habitat

    Friction for speciesmovements

    Minimum patch area

    LANDSCAPE GRAPH

    Construction des graphes paysagers

  • Mapping landscape

    Input data

    Landscape map in raster format

    Categories defined accordingto a species/landscaperelation

    Usually: cost value (friction) for each landscape category

    Construction des graphes paysagers

  • Defining habitat patches

    Patches = graph nodes

    o Minimum patch area

    o Connexity

    o Capacity

    Construction des graphes paysagers

  • Defining habitat patches

    Patches = graph nodes

    o Minimum patch area

    o Connexity

    4-connexity 8-connexity

    Cell adjacent to the orange one

    Focal cell

    1

    3

    4-connexity=> 3 patches

    8-connexity=> 1 patch

    2 1

    1

    1

    Construction des graphes paysagers

  • Defining habitat patches

    Patches = graph nodes

    o Minimum patch area

    o Connexity

    o Capacity

    capacity = intrinsic quality of the patch as an indicator of its demographic potential

    Function of the isotropicneighbourhood

    Area of the habitat patch

    Suitable elements Unfavourable elementsHabitat patches

    Function of the anisotropicneighbourhood

    Construction des graphes paysagers

  • Defining links

    Voronoipolygon

    Construction des graphes paysagers

  • Defining links

    Topology- Complete- Planar

    Direction

    Distance- Euclidean distance- Least-cost distance

    Threshold

    Construction des graphes paysagers

  • Defining links

    Topology- Complete- Planar

    Direction

    Distance- Euclidean distance- Least-cost distance

    Threshold

    Construction des graphes paysagers

  • Defining links

    Topology- Complete- Planar

    Direction

    Distance- Euclidean distance- Least-cost distance

    Threshold

    Construction des graphes paysagers

  • Defining links

    Topology- Complete- Planar

    Direction

    Distance- Euclidean distance- Least-cost distance

    Threshold

    Construction des graphes paysagers

  • Defining links

    Topology- Planar- Complete

    Direction

    Distance- Euclidean distance- Least-cost distance

    Threshold

    Construction des graphes paysagers

  • Defining links

    Topology- Planar- Complete

    Direction

    Distance- Euclidean distance- Least-cost distance

    Threshold

    Construction des graphes paysagers

  • Defining links

    Topology- Planar- Complete

    Direction

    Distance- Euclidean distance- Least-cost distance

    Threshold

    Construction des graphes paysagers

  • Defining links

    Topology- Planar- Complete

    Direction

    Distance- Euclidean distance- Least-cost distance

    Threshold

    Construction des graphes paysagers

  • Defining links

    Land-use categories Function Cost

    1 Ponds Habitat 1

    2 Water Suitable 10

    3 Built-up areas and infrastructures Unfavourable 1000

    4 Forests Suitable 10

    5 Wetlands Suitable 10

    6 Croplands Unfavourable 1000

    7 Grasslands Suitable 10

    8 TGV line Unfavourable 2000

    Construction des graphes paysagers

  • Defining links

    Graph threshold

    only links shorter than the threshold distance are kept.

    (maximum dispersal distance of a given species)

    Construction des graphes paysagers

  • Computing connectivity metrics

    Several levels:

    localcomponentglobal

    Many metrics in graph theoryRayfield B, Fortin MJ, Fall A, 2011. Connectivity for conservation: a framework to classify network measures. Ecology 92: 847-858.

    Construction des graphes paysagers

  • Computing connectivity metrics

    Sum of capacity of patches connected to the patch i

    i

    weighted according to the minimum distance to the focal patch

    => indicator of the potential dispersion from/to the patch i

    Similar to the degree index

    i i

    Construction des graphes paysagers

  • Computing connectivity metrics

    Sum of the shortest paths through the focal patch i.

    i

    weighted both by the capacity of the twoend patches and by the distance betweenthem.

    => frequency of use of the patch i

    Construction des graphes paysagers