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NR 422- Habitat Suitability Models. Jim Graham Spring 2009. Habitat Suitability. Predict the potential distribution of a species based on finding suitable habitat Also known as: Niche modeling Predicting distributions. Terminology. Realized Niche – current distribution
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NR 422- Habitat Suitability Models Jim Graham Spring 2009
Habitat Suitability • Predict the potential distribution of a species based on finding suitable habitat • Also known as: • Niche modeling • Predicting distributions
Terminology • Realized Niche – current distribution • Established species • Late succession (minimal disturbance) • Potential Niche – future distribution? • Invasive species • Theatened and endangered species
Approaches • Mechanistic/Experimental • Based on understanding of a species requirements and experiments • Can miss the complexity of environmental conditions and genetic plasticity • Statistical • Based on the existing distribution of a species • Can miss the “realized niche” • Observational / Anecdotal • Hard to validate
Basic Idea • Basic idea is to find a correlation between a species and a variable we can measure • Temperature • Precipitation • Surface type: Water, Rock, Soil Type • Distance to human activity • Other species!
Process Occurrence Data Experiments And Observations Environmental Layers Statistical Model Parameters and Equations Results Processing Distribution Map Model Validation
Correlations • Correlations between environmental variables and species requirements
Box Model 50 Precipitation (cm/year) 30 5.6 Temperature (degrees C)
Vegetation Layers • Minimum temperatures at certain times of the year • Amount of sun • Precipitation • Soil type • Elevation • Slope • Aspect www.geography.hunter.cuny.edu
Herbivore Layers • Vegetation layers • Proximity to cover • Distance to water www.ministryofpropaganda.co.uk media-2.web.britannica.com
Carnivore Layers • Herbivore layers • Proximity to cover • Distance to water www.juneauempire.com
Proxy Layers • Remotely sensed: • MODIS • LandSat • Aerial • Human disturbance • DEMs: Elevation, slope, aspect
White Tailed Deer • Habitat Suitability Index (HSI) = Forage * Cover • Log(Deer Density) = a + b (HSI) Roseberry, J. L., Woolf, A. 1998. Habitat-Population Density Relationships for White-Tailed Deer in Illinois, Wildlife Society Bulletin, Vol. 26, No. 2 (Summer, 1998), pp. 252-258
Black Bears in Rocky Baldwin, R.A., L. C. Bender. 2007. Den-Site Characteristics of Black Bears in Rocky Mountain National Park, Colorado, JOURNAL OF WILDLIFE MANAGEMENT 72(8):1717–1724
Habitat Suitability Index • HIS = • 0 for least suitable • 1 for most suitable • HIS = V1 * V2 * V3 • Where each VX is a raster scaled from 0 to 1 • 0 = unsuitable factor • 1 = suitable factor • In between values for intermediate suitability
Categories • Assign each category a value from 0 to 1 based on how suitable it is.
Ranges • Create mask rasters for area below and above (0 for unsuitable, 1 for suitable) 1.0 0.0 Mask (0.0) 1.0 Mask (0.0)
Gradients 1.0 0.0 Mask Gradient 1.0
Envelopes 1.0 0.0 Mask Gradient 1.0 Gradient Mask
Statistical Approaches • Linear Regression (continuous variables) • Logistic Regression (presence data) • Genetic Algorithm for Rule-set Production : GARP • Classification and Regression Trees: CART • MaxEnt (presence)
Integrating Climate Change Japanese Honeysuckle
Where to go from here • Spatial modeling • Robin’s class • OpenModeler