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Monitoring grass swards using imaging spectroscopy
Author(s) -
Schut A. G. T.,
Ketelaars J. J. M. H.
Publication year - 2003
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1046/j.1365-2494.2003.00379.x
Subject(s) - interception , lolium perenne , dry matter , leaf area index , biomass (ecology) , yield (engineering) , environmental science , zoology , agronomy , chemistry , poaceae , biology , physics , ecology , thermodynamics
The potential of an imaging spectroscopy system with high spatial (0·16–1·45 mm 2 ) and spectral resolution (5–13 nm) was explored for monitoring light interception and biomass of grass swards. Thirty‐six Lolium perenne L. mini‐swards were studied for a total of eleven consecutive growth periods. Hyperspectral images and light interception (LI) were recorded twice weekly. On two dates ground cover was scored visually ( GC v ). At harvest, leaf area index (LAI), fresh‐matter yield and dry‐matter yield (DMY) were determined. Classification of images yielded several estimates of the image ground cover ( GC i ) and the index of reflection intensity (IRI). The GC i was highly correlated with GC v ( = 0·94), LAI ( = 0·88) and LI ( = 0·95, for dense swards under cloudy skies). However, the relationship between GC i and LI depended on sky conditions and sward structure. Under cloudy skies, LI was linearly related to GC i , whereas under clear skies, this relation was logistic. Regression analysis of GC i and yields showed correlations with of between 0·75 and 0·82. The mean error of DMY estimates was 340 kg. In conclusion, estimates of GC i and IRI can be used to predict DMY, even for high yield levels (up to 3500 kg DM ha −1 ), allowing accurate, non‐destructive monitoring of biomass and light interception of grass swards.