Landscape Ecology. I.A Landscape Perspective A. Integrating Communities and Ecosystems forest field.

Landscape Ecology

Landscape Ecology

I.A Landscape PerspectiveA. Integrating Communities and Ecosystems

forest

field

Landscape Ecology

I.A Landscape PerspectiveA. Integrating Communities and Ecosystems

forest

field

How Do:Habitat typesPatch sizesPatch ArrangementConnectivity

Affect:Species DistributionsCommunity ParametersEcosystem Processes

Landscape Ecology

I.A Landscape PerspectiveA. Integrating Communities and EcosystemsB. Landscape Elements

1. Landscape: A landscape is any bounded area. It can be small (1m2) or large… up to a biome. However, for it to be an interesting level of organization to study, it must be heterogeneous… (the focus is on interactions between patches, so there must be > 1)

B. Landscape Elements

1.Landscape:2. Matrix: the element with the greatest area and connectivity. The primary ‘cover type’ in the landscape - the ‘background’ in which patches and corridors exist. Exerts the greatest degree of control over landscape dynamics, as a consequence of the ‘permeability’ of the matrix.

Forest as MatrixForest as Patch in Grassland Matrix


1.Landscape:2. Matrix:3. Patch: a ‘bounded area’ (that can be defined by coordinates and ‘mapped’) embedded in the matrix. Important characteristics are size, shape, origin (disturbance? Remnant?), number location; functions are habitat type, migratory stepping stones, and source/sink relationships.


1.Landscape:2. Matrix:3. Patch:4. Corridor: These are narrow ‘patches’ that differ from neighboring patches, matrix, or corridors. Corridors both divide and connect patches. Characteristics are width, length, and perhaps volume; they have an origin and may contain an internal entity (stream) that adds complexity. They function as habitat, conduit, barrier/filter, source/sink.

Landscape Ecology

I.A Landscape PerspectiveA. Integrating Communities and EcosystemsB. Landscape ElementsC. Scale

“For it to be an interesting level of organization to study, [a landscape] must be heterogeneous… (the focus is on interactions between patches, so there must be > 1)

Landscape Ecology

I.A Landscape PerspectiveA. Integrating Communities and EcosystemsB. Landscape ElementsC. Scale

“For it to be an interesting level of organization to study, [a landscape] must be heterogeneous… (the focus is on interactions between patches, so there must be > 1)”

How Do:Habitat typesPatch sizesPatch ArrangementConnectivity

Affect:Species DistributionsCommunity ParametersEcosystem Processes

Independent Variables Dependent Variables

Must be multiple levels of an independent variable to assess the effect of that variation on a dependent variable.

C. Scale

“viewer defined” –the scientist

C. Scale“viewer defined” –the scientist“user defined” – the organism

Coarse: purple

Fine:Heterogeneous

C. Scale“grain”

C. Scale

Coarse Grained = “field”

C. Scale

Fine Grained ‘patches’

C. Scale1. Species responses vary at different scales, so scalar analysis can reveal the scale of importanceAt which scale does amount of wetland habitat correlate best with local abundance?

II. Insights from Landscape EcologyA. Patch Size Matters

1. Species-area Effects:Smaller patches, fewer species


1. Species-area Effects: Smaller patches, fewer species2. Loss of Predators and Keystone Effects: Animals at the top of a trophic pyramid, which are already at low density, are more sensitive to patch size reduction. These are predators. When predators are lost, competition in lower levels increases.


1. Species-area Effects: Smaller patches, fewer species2. Loss of Predators and Keystone Effects: Animals at the top of a trophic pyramid, which are already at low density, are more sensitive to patch size reduction. These are predators. When predators are lost, competition in lower levels increases. 3. Increase in particular populations and their pathogens: The animals that remain reach higher densities (not necessarily larger populations on the smaller island, but higher density. At higher densities, transmission rates of pathogens increase.

Lyme Disease:

- fragmentation reduces patch size

- abundance of predators like fox declined

- white-footed mice (host of Borrela burgdorferi bacterium) increase.

- increase host density, increase infection rate of ticks.

West Nile Virus

Swaddle and Carlos, 2008. PLoS one 3:e2488

Low Diversity: High Relative Abundance of Hosts

High Diversity: Low Relative Abundance of Hosts

II. Insights from Landscape EcologyA. Patch Size MattersB. Connectance Matters

Increased connectivity among patches allows for the ‘rescue effect’ and increased species colonization and persistence on patches.


Underpasses in everglades restores animal movement and reduces mortality from cars.





Mesoamerican Biological Corridor


San Juan – La Selva Biological Corridor



II. Insights from Landscape EcologyA. Patch Size MattersB. Connectance MattersC. Scale Matters

1. different species respond at different scales

II. Insights from Landscape EcologyA. Patch Size MattersB. Connectance MattersC. Scale Matters

2. Measuring Diversity at a Landscape Scale

α – alpha diversity: this is the diversity within a habitat unit, or the mean diversity among units of the same habitat type.

β-beta diversity: typically, this refers to the ‘diversity’, or difference, among communities using different habitat types. (α = 6 for forest, α = 6 for field). We can calculate the Beta diversity as:(S1 – c) + (S2 – c),

γ-gamma diversity: This is the total diversity across the entire landscape, regardless of habitat. So, if the forest and field have no species in common, then gamma diversity = 12. If the forest and field share 2 species, then gamma = 10 (6 in the forest, and four additional NEW species in the field).

Landscape Ecology. I.A Landscape Perspective A. Integrating Communities and Ecosystems forest field.

Documents

landscape elements

landscape ecology slide

landscape perspective

landscape dynamics

scale grain slide

scientist slide

organism slide

grassland matrix slide