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ForestERA Metadata - Quadratic Mean Diameter

Description

Abstract

This is a 90m resolution raster dataset describing quadratic mean diameter (QMD) 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 wildlife habitat modeling, fire behavior modeling, modeling forest management, and forest management planning.

Supplementary Information

This layer was created using the basal area (BA) and tree density (TD) layers created by the ForestERA team. To produce the QMD layer from those two layers, use the following equation: QMD = 2 * SQRRT((BA * 10,000) / TD) / 3.14157).

An external accuracy assessment was performed on the QMD layer using linear regression and 567 points of ground data collected by our field crew at 63 locations scattered across the study area. We used linear regression to compare actual QMD values measured at the ground locations with QMD values predicted using the procedure above. The results of this analysis indicated that a significant relationship exists between the two measures (Fig. 1; r² = 0.158, P < 0.001). The slope of the line from this relationship is 1.00 indicating that the ETM derived QMD estimate is unbiased in relation to the ground estimate. However, the relatively low r² value indicates that there is not a particularly strong relationship between the predicted QMD and the actual QMD, even though strong relationships existed between the predicted basal area and tree density layers and actual basal area and tree densities on the ground. Because this layer has generally low accuracy and many assumptions must be taken into consideration when it is used, we do not recommend its use for most modeling purposes, especially predicting tree sizes across the landscape in anything other than very general terms.

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: As needed

Time period for which the data is relevant

Date and time: 1997
Description:
publication date

Publication Information

Who created the data: Forest Ecosystem Restoration Analysis Project

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

File name: qmd90m
Type of data: raster digital data

Location of the data:

\\ENVSCI41\Shared\metadata_layers\grids\qmd90m
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: 22.969 MB
Data transfer size: 22.969 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 14350500

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