Assessment of vegetation stress using reflectance or fluorescence measurements.
Current methods for large-scale vegetation monitoring rely on multispectral remote sensing, which has serious limitation for the detection of vegetation stress. To contribute to the establishment of a generalized spectral approach for vegetation stress detection, this study compares the ability of high-spectral-resolution reflectance (R) and fluorescence (F) foliar measurements to detect vegetation changes associated with common environmental factors affecting plant growth and productivity. To obtain a spectral dataset from a broad range of species and stress conditions, plant material from three experiments was examined, including (i) corn, nitrogen (N) deficiency/excess; (ii) soybean, elevated carbon dioxide, and ozone levels; and (iii) red maple, augmented ultraviolet irradiation. Fluorescence and R spectra (400-800 nm) were measured on the same foliar samples in conjunction with photosynthetic pigments, carbon, and N content. For separation of a wide range of treatment levels, hyperspectral (5-10 nm) R indices were superior compared with F or broadband R indices, with the derivative parameters providing optimal results. For the detection of changes in vegetation physiology, hyperspectral indices can provide a significant improvement over broadband indices. The relationship of treatment levels to R was linear, whereas that to F was curvilinear. Using reflectance measurements, it was not possible to identify the unstressed vegetation condition, which was accomplished in all three experiments using F indices. Large-scale monitoring of vegetation condition and the detection of vegetation stress could be improved by using hyperspectral R and F information, a possible strategy for future remote sensing missions.
Campbell
P K E
PK
Joint Center for Earth Systems Technology, Univ. of Maryland, Baltimore County (UMBC), Baltimore, MD 20771, USA. pcampbel@pop900.gsfc.nasa.gov
Middleton
E M
EM
McMurtrey
J E
JE
Corp
L A
LA
Chappelle
E W
EW
D031002:Acer / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D002245:Carbon Dioxide / Q000378:metabolism / Q000494:pharmacology; D004784:Environmental Monitoring / Q000379:methods; D009584:Nitrogen / Q000378:metabolism / Q000494:pharmacology; D010126:Ozone; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D013025:Glycine max / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014466:Ultraviolet Rays / Q000009:adverse effects; D003313:Zea mays / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects
D002245:Carbon Dioxide; D010126:Ozone; D009584:Nitrogen