J. Pinol et al., GROUND-BASED SPECTRORADIOMETRIC ESTIMATION OF LIVE FINE FUEL MOISTUREOF MEDITERRANEAN PLANTS, Agricultural and forest meteorology, 90(3), 1998, pp. 173-186
We developed a method to estimate live fine fuel moisture (LFFM) by gr
ound-based, high-resolution plant reflectance measurements in the visi
ble and near infrared regions. NDVI and WT (R-970/R-900) were the refl
ectance indices used because they provided the best estimation of LFFM
. The performance of the method was evaluated (1) by measuring monthly
plant reflectance and LFFM in adult plants growing in the field, and
(2) in a desiccation experiment carried out with potted seedlings in a
plastic tunnel. The species studied in the field site consisted of tw
o deep-rooted shrubs (Arbutus unedo and Quercus coccifera), two shallo
w-rooted shrubs (Cistus albidus and C. monspeliensis), and one grass (
Brachypodium retusum). The species studied in experimental conditions'
were two trees (Pinus halepensis and e. ilex), and six shrubs (Arbutu
s unedo, e. coccifera, C. albidus, C. monspeliensis, Phillyrea angusti
folia, and Pistacia. lentiscus). During desiccation, the 970 nm trough
tended to disappear (consequently, the WI increased), and the reflect
ance in the red increased (consequently, the NDVI decreased). The two
reflectance indices NDVI and WI were significantly correlated with LFF
M when all the species were considered together and within most of the
individual species, both in the field and in potted seedlings. We pro
pose a method consisting of a simple radiometer measuring plant reflec
tance at 680, 900, and 970 nm, that could speed up the measurement of
LFFM, and that could be useful in wildfire risk evaluation. (C) 1998 E
lsevier Science B.V.