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ForestERA Metadata - Tassel-eared Squirrel Density and Recruitment

Abstract

These are 90m resolution raster datasets describing predicted Tassel-eared Squirrel density (Squirrels / Ha) and recruitment (Juveniles / Ha) across the western Mogollon Plateau in Arizona. It was created as part of the Forest Ecosystem Restoration Analysis (ForestERA) project to support landscape-scale forest restoration planning efforts by a broad group of stakeholders including federal and state agencies, academic institutions, and non-governmental entities.

Purpose

This layer was developed by the ForestERA project for use in landscape-level planning and prioritization of forest management on the western Mogollon Plateau. It was designed for multiple purposes, including prioritization of management actions and assessment of management effects on squirrel populations.

Supplementary Information

This layer was developed from field data collected by Norris Dodd of the Arizona Game and Fish Department on nine 280 ha study sites spread across the Western Mogollon Rim between 2000 and 2003. In our modeling approach, we used Norris Dodd's estimates of squirrel density and recruitment from 2 sampling plots, each 24 ha in size, from each of his study areas (n = 18 sampling plots). Using linear regression, we linked these to layers representing forest structural attributes developed from remotely sensed imagery by the ForestERA project.

We developed a-priori hypotheses about the influence of forest structure on squirrel density and used the relationships between the remotely-sensed data layers and squirrel density to develop a set of candidate models for analysis. We used Akaike's Information Criterion (AIC) and an information-theoretic approach to assess the strength of these models and choose the most strongly supported model from the set of candidate models. Our most strongly supported model for Tassel-eared Squirrel density and recruitment were;

Squirrel Density = -0.1815 + (0.0206 * basal area).

Squirrel Recruitment = -0.1710 + (0.0076 * basal area) + (0.0007 * canopy cover variant) + (0.0001 * interaction effect)

In the squirrel recruitment model, the canopy cover variant was created by determining the number of cells with cover greater than 50% over a 160 ha extent. In ArcGIS this involved converting the canopy cover layer to a binary layer (cells with cover > 50% reclassified as 1, other cells reclassified as 0). Then, a neighborhood focalsum operation was used on this layer (focalsum of a circle with a radius of 8 pixels).

Adjusted r-squared values indicated that these models were doing a good job of explaining variance in squirrel density (r² = 0.84) and recruitment (r² = 0.72). To do a rigorous accuracy assessment for these layers would require the collection of a great deal of ground data on squirrel density and recruitment. However, we were able to do a limited assessment using data collected by Norris Dodd on seven independent study plots in the mid 1990's. We obtained the boundaries for these study plots and estimated squirrel density for each of those plots using our models. Using linear regression, we compared these estimates with estimates of squirrel density and recruitment obtained on each plot during the field study. This analysis indicated that there were statistically significant relationships between the two estimates for squirrel density (F = 7.6, P = 0.04, r² = 0.60, m = 0.84, d.f. = 6), and squirrel recruitment (F = 9.3, P = 0.03, r² = 0.65, m = 0.47, d.f. = 6).

These data are intended for regional analyses over spatial extents on the order of tens to hundreds of thousands of acres, and were not developed for use at finer spatial scales, although they may be useful for some applications at those finer scales.

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Status of the data

Complete
Data update frequency: None planned

Time period for which the data is relevant

Date and time: 2000
Description:
publication date

Publication Information

Who created the data: Forest Ecosystem Restoration Analysis Project

Date and time: December 1, 2004
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Data storage and access information

File name: firerisk90m
Type of data: raster digital data

Location of the data:
\\ENVSCI41\Shared\metadata_layers\grids\tesdens90m

\\ENVSCI41\Shared\metadata_layers\grids\tesrecruit90m
Data processing environment: Microsoft Windows 2000 Version 5.0 (Build 2195)
Service Pack 4; ESRI ArcCatalog 8.1.2.671

Accessing the data

Size of the data: 22.340 MB
Data transfer size: 22.340 MB

Constraints on accessing and using the data

Access constraints: This layer may be accessed by any interested party. It is
provided by the Forest Ecosystem Restoration Analysis project, the Ecological
Restoration Institute (ERI), and Northern Arizona University (NAU).

Use constraints:
This layer is provided for public use by the ForestERA project, ERI, and NAU.
Reports, presentations, and publications in which this layer is presented or
used for analytical purposes should acknowledge the ForestERA project.

Details about this document

Contents last updated: 20040421 at time 14425800

Who completed this document

Forest Ecosystem Restoration Analysis Project
Center For Environmental Sciences and Education:
Northern Arizona University
Flagstaff, Arizona 86011-5694
United States
928-523-0068 (voice)
928-523-7423 (fax)

Contact Instructions:

Contact Dr. Thomas D. Sisk or the Forest Ecosystem Restoraton Analysis Project.

Standards used to create this document

Standard name: FGDC Content Standards for Digital Geospatial Metadata
Standard version: FGDC-STD-001-1998
Time convention used in this document: local time
Metadata profiles defining additonal information
ESRI Metadata Profile: http://www.esri.com/metadata/esriprof80.html

Horizontal coordinate system

Projected coordinate system name: NAD_1983_UTM_Zone_12N
Geographic coordinate system name: GCS_North_American_1983
Details
Grid Coordinate System Name: Universal Transverse Mercator
UTM Zone Number: 12
Transverse Mercator Projection
Scale Factor at Central Meridian: 0.999600
Longitude of Central Meridian: -111.000000
Latitude of Projection Origin: 0.000000
False Easting: 500000.000000
False Northing: 0.000000

Planar Coordinate Information

Planar Distance Units: meters
Coordinate Encoding Method: row and column
Coordinate Representation
Abscissa Resolution: 90.000000
Ordinate Resolution: 90.000000

Geodetic Model

Horizontal Datum Name: North American Datum of 1983
Ellipsoid Name: Geodetic Reference System 80
Semi-major Axis: 6378137.000000
Denominator of Flattening Ratio: 298.257222
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Bounding coordinates

Horizontal
In decimal degrees
West: -113.044931
East: -109.878536
North: 35.587479
South: 34.107751
In projected or local coordinates
Left: 314687.387285
Right: 601607.387285
Top: 3938195.572581
Bottom: 3775925.572581
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Spatial data description

Raster dataset information
Raster format: ESRI GRID
SDTS raster type: Grid Cell
Number of raster bands: 1
Raster properties
Origin location: Upper Left
Has pyramids: FALSE
Has colormap: FALSE
Data compression type: Default
Display type: matrix values
Cell information
Number of cells on x-axis: 3188
Number of cells on y-axis: 1803
Number of cells on z-axis: 1
Number of bits per cell: 32
Cell Size
X distance: 90.000000
Y distance: 90.000000

No detailed attribute information is available.

Page last updated February 11, 2005