WWETAC Projects

Project Title: Assessment review of remote sensing technologies for threat detection

Principal Investigator: Lee A. Vierling, Geospatial Laboratory for Environmental Dynamics, University of Idaho, Moscow, ID; Jan U.H. Eitel, McCall Outdoor Science School, University of Idaho, McCall, ID


Key Issues/Problems Addressed:

Multiple plant stresses affect the health, aesthetic condition, and timber harvest value of conifer forests. Remote sensing may provide timely, accurate, and cost-effective information that is needed to monitor spatial and temporal dynamic forest stress conditions. 

Setting and Approach:

Satellite imagery has recently become available via the RapidEye satellite constellation which provides spectral information in five broad bands, including the red-edge region (690-730 nm) of the electromagnetic spectrum. A field investigation assessment and a literature review of 60 peer-reviewed articles were conducted to investigate current advances in detecting plant stress using remote sensing techniques.

The field component tested the hypothesis that broadband, red-edge satellite information improves early detection of stress in a woodland ecosystem relative to the more commonly used band combinations of red, green, blue, and near infrared band reflectance spectra.  A piñon-juniper woodland in central New Mexico was evaluated using a temporally dense time-series of 22 RapidEye scenes acquired before and after stress was induced by girdling trees.

Key Findings:

In the field study, the Normalized Difference Red-Edge index (NDRE) allowed stress to be detected 13 days after girdling, which is between 12 to 16 days earlier than traditionally used broadband spectral indices such as the Normalized Difference Vegetation Index (NDVI) and the Green NDVI.  Based on the literature review, a conceptual framework was developed that could be used as a decision support tool for optimizing approaches to detect early onset of plant stress, after due consideration of the amount of signal (vs. noise) that can be captured via the different remote sensing approaches.    


The red-edge region (690-730 nm) of the electromagnetic spectrum has potential to improve forest stress monitoring from satellites.  Remote sensing data fusion approaches may be useful for detecting and mapping plant stress within a decision support framework.


Eitel, J.U.H., L.A.Vierling, M.E. Litvak, D.S. Long, U. Schulthess, A.A. Ager, D. Krofcheck, and L. Stocheck. 2011.  Broadband, red-edge information from satellites improves early stress detection in a New Mexico conifer woodland.  Remote Sensing of Environment 115: 3640-3646.  doi:10.1016/j.rse.2011.09.002. (PDF, 787 KB)

WWETAC Project ID: FY10AA78