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Project ID: 13-3-01-28

Year: 2013

Date Started: 08/01/2013

Date Completed: 03/31/2015

Title: Quantifying Post-Fire Ponderosa Pine Snags Using GIS Techniques on Scanned Aerial Photographs

Project Proposal Abstract: Snags are an important component of forest ecosystems because of their utility in forest-nutrient cycling and provision of critical wildlife habitat, as well as associated fuel management concerns relating to coarse woody debris (CWD) loads. Knowledge of snag and CWD trajectories are needed for land managers to plan for long-term ecosystem change in the post fire regimes. This need will likely be exacerbated by increasingly warm and dry climatic conditions projected for the U.S. Southwest. One of the best prospects for studying fire-induced landscape change beyond the field-plot level, but still at a resolution sufficient to resolve individual snags, is to utilize the available aerial photograph record. Previous field-based studies of snag and CWD loads in the Southwest have relied on regional chronosequences to judge the recovery dynamic of Ponderosa Pine burns. This previous research has been spatially and temporally restricted because of ground survey extent limitations and uncertainty associated with the chronosequence approach (i.e. space-for-time substitution), which does not consider differences between specific site conditions and histories. The objective of this study is to develop automated tools for quantifying and characterizing the spatial and temporal distribution of large snags and CWD associated with severe forest fires from very high resolution (VHR) landscape imagery. The novel data that is generated will then be applied to test hypotheses that patterns of burn severity and topographic controls (e.g. slope, aspect, elevation, and other terrain characteristics) are a key controlling variable for snag and CWD dynamics on hillslopes, including the quantity, character, and spatial configuration and of snags and logs. We (Student Investigator Kevin Kent and Principle Investigator Erik Schiefer) will use our strong computing and Geographic Information Systems (GIS) backgrounds to develop transferable tools for classifying and spatially inventorying snags and CWD over several decades from VHR remote sensing imagery. Large snags and CWD are generally easy to resolve from VHR imagery and algorithms can be developed to rapidly identify and characterize (e.g. size, standing or downed, orientation) those features over time. These algorithms will utilize the sharp edges, shape, shadow, and contrast characteristics of snags and logs to enable feature recognition. This research will expand on the field-based projects of Passovoy and Fulé (2006) and Roccaforte et al. (2012) through the development of automated tools for identifying and classifying snags and CWD associated with severe wildfires in the Southwest. The availability of field survey data to calibrate these new tools for ponderosa pine forests allows this to be a streamlined and technology-focused project. We will use these tools to generate a dataset which will allow us to then extend the supported project to include a reassessment of previous research findings on snag and CWD trajectories following fire. An exciting application of these tools and associated geospatial data is the ability to then assess topographic controls on snag and CWD change over intra- to inter-decadal timescales and extend such findings to describe the trajectory of these important ecosystem components to a larger landscape scale. The research outlined in this proposal closely parallels Kevins MS thesis topic, which has been approved his graduate committee. JFSP support would allow this project to be expanded to a multi-temporal framework, instead of just working with a single snapshot of imagery. It would also support the development of Kevins algorithms into well-documented, stand-alone packages for use by other researchers and land use managers interested in being able to quickly quantify CWD features from high-resolution imagery.

Principal Investigator: Erik K. Schiefer

Agency/Organization: Northern Arizona University

Branch or Dept: Department of Geography, Planning & Recreation

Other Project Collaborators




Branch or Dept

Agreements Contact

Cindy L. Judge

Northern Arizona University

Office of Grant & Contract Service

Budget Contact

Cindy L. Judge

Northern Arizona University

Office of Grant & Contract Service

Student Investigator

Kevin M. Kent

Northern Arizona University

Department of Geography, Planning & Recreation

Project Locations

Fire Science Exchange Network







Interior West


Project Deliverables

Final Report view or print

("Results presented in JFSP Final Reports may not have been peer-reviewed and should be interpreted as tentative until published in a peer-reviewed source.")

  ID Type Title
view or print   7621 Computer Model/Software/Algorithm Quantifying Post-Fire Ponderosa Pine Snags Using GIS Techniques on Scanned Aerial Photographs

Supporting Documents

There are no supporting documents available for this project.

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