Presentation on theme: "Landscape Pattern I.Landscape Components (attributes of features or spatial elements) landscape are comprised of: - corridors - patches - matrix."— Presentation transcript:
Landscape Pattern I.Landscape Components (attributes of features or spatial elements) landscape are comprised of: - corridors - patches - matrix
Landscape Pattern I.Landscape Components (attributes of features or spatial elements) landscape are comprised of: - corridors - patches - matrix A.Composition B.Configuration C.Connectivity Relative to landscape spatial elements….
How much of the area is comprised of each type of spatial element? How are spatial elements arranged in space? How do these attributes change through time?
How does one quantify landscape pattern? How do biotic communities interact with pattern?
Patch – relatively homogeneous ecological unit; differentiated from landscape as a whole Corridor – linear element that differs from matrix on either side; form & context determines function (habitat, conduit, barrier, filter) Matrix – element encompassing greatest relative area; most connected; dominant role in landscape dynamics Landscape Pattern Patch-Corridor-Matrix Model
Landscape Pattern Patches Defining patches using vector data Digitizing = delineating polygon patches using remotely- sensed data (e.g., DOQ) based on visual interpretation of patch boundaries; subjective, but ground truthing needed DOQ Vector Coverage
Landscape Pattern Patches Defining patches using raster data Satellite sensor = delineating pixel-shaped patches based on spectral signatures; aggregating cells based on shared attributes DOQ Raster Coverage
Patch defined relative to phenomenon investigated (scale relevant) Patches are dynamic and occur at a multiple scales (space & time) Patch boundaries meaningful only when referenced to particular scale & phenomenon; resolution impt., gradients or discrete boundaries? Landscape Pattern Patches
Definition based on function….. Habitat – increase connectivity by providing breeding habitat…facilitate gene flow Facilitated Movement – increase connectivity by facilitating dispersal, migration, and/or range shifts Barrier or Filter – prohibit (barrier) or impede differentially (filter) movements Landscape Pattern Corridors
Facilitated Movement Corridors Roads/right-of- ways Woody strips, windbreaks, fencerows Riparian corridors Landscape Pattern Corridors Do corridors function to facilitate movement of organisms among patches, thereby mitigating against land use in the matrix?
Facilitated Movement Corridors Selectivity (s): degree of discrimination of possible pathways Resistance (k): survival cost per unit time spent in corridor Velocity (v): avg rate of movement through Final evaluation = immigration rate Landscape Pattern Corridors
Barriers & Filters Roads/right-of- ways Riparian corridors Landscape Pattern Corridors Do corridors function to prevent or impede movement of organisms among patches and across the landscape (i.e., decrease landscape connectivity)? Yes, but dependent on: –Corridor type & width –Frequency of human and other spp. activity in corridor –Mobility & behavior of species
Most abundant and highest connectivity Defined relative to phenomenon studied Dynamic and variable with scale Influences choice of landscape metrics for measuring pattern Landscape Pattern Matrix
Causes of Landscape Pattern Physical Template Inferences about physical gradients are confounded because: Each factor has specific spatial scale = behaves at its own scale: –Soil depth & texture cm and all other scales –Topography 10’s to 100’s m –Temperature 100’s m (elevation) or 100’s km (latitude) –Precipitation 100’s m (elevation)
Common N.A. trees – contractions & radiations in distribution
Modeling Changes in Landscape (vegetative) Patterns – Global Climate Change
Causes of Landscape Pattern Biotic Factors –Competition –Predation
Causes of Landscape Pattern Competition –Competitive exclusion could lead to homogenous spatial pattern at least at some spatial scale –Multiple stable states (stochastic disturbance patterns can mitigate influence of competition) (e.g., Allee Effect) –Influence of disturbance events (abiotic and human)
Causes of Landscape Pattern Competition –Species-mediated interactions (e.g., keystone sp.) Dominant organisms (typically impact processes and pattern over large spatial and temporal scales) – primarily herbivores? –e.g., beaver, bison, elephants, other megafauna? –Pleistocene megafauna and vegetation patterns
Causes of Landscape Pattern Predation –keystone sp –ecology of fear –Trophic cascades
Causes of Landscape Pattern Human Land Use –Prehistoric, Historic, Present Effects Shift from nomadic hunter-gatherer to farming systems
Human Land Use Practices 1)Agriculture 2)Suburban Development *Landuse / Landcover Data from USGS sources (typically resolution to 30 m)
Causes of Landscape Pattern Human Land Use –Present Effects Extraction of natural resources Patterns of development Transportation networks