modeling potential distribution of common plant species in

Modeling Potential Distribution Modeling Potential Distribution of Common Plant Species in of Common Plant Species in

Northern UtahNorthern Utah

R. Douglas Ramsey

Department of Wildland Resources

College of Natural Resources

Utah State University

ObjectiveObjective

Model the potential spatial distribution of individual plant species to better quantify and understand current conditions.

Model the potential spatial distribution of individual plant species to better quantify and understand current conditions.

Ecological Site DescriptionsEcological Site Descriptions

“A distinctive kind of land, with specific physical characteristics, which differs from other kinds of land in its ability to produce a distinctive kind and amount of vegetation, and in its response to management”

“A distinctive kind of land, with specific physical characteristics, which differs from other kinds of land in its ability to produce a distinctive kind and amount of vegetation, and in its response to management”

Common framework for communication of resource information among disciplines, agencies, and organizations

Common framework for communication of resource information among disciplines, agencies, and organizations

Ecological Sites form a “Reference State”

for

State and Transition Models.

Ecological Sites form a “Reference State”

for

State and Transition Models.

State and Transition theory outlines landscape change scenarios by which land managers can use to determine management prescriptions

State and Transition theory outlines landscape change scenarios by which land managers can use to determine management prescriptions

Reference State Reference State

ThresholdThresholdThreshold

State 1State 1State 1



ThresholdThresholdThreshold

Reversible transitionReversible transitionReversible transition

Community pathway(within states)Community pathwayCommunity pathway(within states)(within states)

Irreversible transitionIrreversible transitionIrreversible transition

Plant community phasePlant community phasePlant community phase

Spatial Location of ESDs within Soil Map UnitsSpatial Location of ESDs within Soil Map Units

•

Soil Map Units can consist of 1-4 components represented as a percentage of each soil map unit. Components refer to a soil with specific characteristics that are different from other components in that map unit. Including

the ESD.

•

Therefore, a soil map unit can consist of 4 different ESD’s who’s % composition within a map unit is known, but has unknown location

within that map unit.

•

Soil Map Units can consist of 1-4 components represented as a percentage of each soil map unit. Components refer to a soil with specific characteristics that are different from other components in that map unit. Including

the ESD.

•

Therefore, a soil map unit can consist of 4 different ESD’s who’s % composition within a map unit is known, but has unknown location

within that map unit.

SSURGO, SMU W/ 4 Component Soils

SSURGO, SMU W/ 4 Component Soils

SWGap Land cover distribution within one SMU

SWGap Land cover distribution within one SMU

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Fre

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How do we model potential plant species?How do we model potential plant species?

Step 1: Identify which plant species occur in the area, which are common, and which would be useful to differentiate ecological sites.

Step 1: Identify which plant species occur in the area, which are common, and which would be useful to differentiate ecological sites.

Step 2: Acquire or collect geo-referenced field data pertaining to species of interest.

Step 2: Acquire or collect geo-referenced field data pertaining to species of interest.

Step 3: Decide which biophysical variables are important for determining potential plant distributions.

Step 3: Decide which biophysical variables are important for determining potential plant distributions.

Step 4: Using a GIS, extract biophysical information and/or indices from available or modeled data layers.

Step 4: Using a GIS, extract biophysical information and/or indices from available or modeled data layers.

Step 5: Correlate plant species occurrence with biophysical attributes and/or indices.

Step 5: Correlate plant species occurrence with biophysical attributes and/or indices.

Distribution BLM and USU evaluation sample locations.

Distribution BLM and USU evaluation sample locations.

Utilizing Logistic Regression to map probability of plant

distribution

Utilizing Logistic Regression to map probability of plant

distribution

Potential Plant Community

soil water availability

temperature intra-

& inter-

species

competition

herbivory

soil depth

soil texture

parent materialsolar radiation

time

pedogenic processes

water gains water losses

precipitation

water run-on water run-off

elevation

relative humidity

upslope contributions

concavity

convexity

slope

evapotranspiration

evapotranspiration

water availability

stochastic events

plants/animals

wind

soil nutrient availability

water infiltration

soil water holding capacity

Once we understand how biophysical attributes relate to plant species distributions…

We can make potential species distribution maps.

In our case, we use a logistic regression approach

Modeled potential distributionWyoming big sagebrush

mountain big sagebrushbasin big sagebrush

black sagebrushjuniper

We can then use our maps to help correlate ecological sites to soil map units.

Examples of logistic regression model outputs. Probabilities are shown as percent values rather than decimal values.

Examples of logistic regression model outputs. Probabilities arExamples of logistic regression model outputs. Probabilities are shown as e shown as percent values rather than decimal values.percent values rather than decimal values.

Questions?Questions?

modeling potential distribution of common plant species in

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