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

Polar Bear

Tamarisk

Red Squirrel

Arctic Tern

Blue Whale

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 Parameters and Equations Results Statistical Model Distribution Map Environmental Layers Processing Model Validation Experiments And Observations

Correlations Correlations between environmental variables and species requirements

Tamarix – Invasive Species

Tamarix and Precipitation

Tamarix and Temperature

Box Model Temperature (degrees C) Precipitation (cm/year)

Tamarix Potential Habitat

Vegetation Layers Minimum temperatures at certain times of the year Amount of sun Precipitation Soil type Elevation Slope Aspect

Herbivore Layers Vegetation layers Proximity to cover Distance to water

Carnivore Layers Herbivore layers Proximity to cover Distance to water

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 Habitat-Population Density Relationships for White-Tailed Deer in Illinois, Wildlife Society Bulletin, Vol. 26, No. 2 (Summer, 1998), pp

Black Bears in Rocky Baldwin, R.A., L. C. Bender 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) Mask (0.0) 1.0

Gradients Mask1.0Gradient

Envelopes Mask 1.0Gradient

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