@article {KNZ00130,
	title = {Assessing grassland biophysical characteristics from spectral measurements},
	journal = {Remote Sensing of the Environment},
	volume = {20},
	year = {1986},
	pages = {141 -152},
	abstract = {<p>Remote sensing offers a potential alternative to tedious hand sampling as a means of monitoring vegetation condition and estimating productivity over large areas of grasslands. This sutdy was conducted to assess the use of spectral reflectance measurements in estimating grass canopy leaf area index (LAI) and total above ground green phytomass. Spectral reflectance measurements were made on a tallgrass prairie during 1983 and 1984 with two multiband radiometers. Green leaf-area index and dry matter accumulations (green above-ground phytomass) were measured on the area monitored by the radiometer. Three indices-near infrared to red ratio, greenness, and normalized difference-were computed from spectral reflectance data. The direct relationships between these special reflectance indices and grass biophysical parameters (LAI and phytomass) were site-dependent and year-specific. Indirect methods of estimating LAI and phytomass from estimates of absorbed, phytosynthetically active radiation, based on measurements of grass canopy spectral reflectance, were found to be more consistent across treatments for the two years of this study</p>},
	keywords = {LTER-KNZ, tallgrass prairie},
	doi = {10.1016/0034-4257(86)90019-2},
	author = {Weiser, R.L. and Asrar, G.A. and Miller, G.P. and Kanemasu, E.T.}
}
@article {KNZ00109,
	title = {Light interception and leaf area estimates from measurements of grass canopy reflectance},
	journal = {IEEE Transactions of Geoscience and Remote Sensing},
	volume = {GE-24},
	year = {1986},
	pages = {76 -82},
	abstract = {<p>Grassland is a major component of the Earth\&$\#$39;s available land. The vast area and remoteness of this ecosystem makes it difficult to assess its condition and monitor productivity by traditional methods. Remote sensing potentially offers a rapid nondestructive approach for monitoring such ecosystems. A study was carried out in a tallgrass prairie site near Manhattan, Kansas, during the 1983 and 1984 seasons to investigate the feasibility of estimating light interception and green leaf area index (LAI) from measurements of canopy multispectral reflectance. Greenness (Gn) index was found to be strongly correlated with intercepted photosynthetically active radiation (PAR). Two methods, a direct regression (RGR) and an indirect approach (IND), were used to estimate LAI form Gn index. The LAI values estimated by RGR method were consistently lower than the measured ones; however, good agreement was obtained between the LAI values estimated by IND method and the measured LAI. This suggests that Gn transformation of canopy spectral reflectance is more closely related to the fraction of intercepted PAR by green foliage than the quantity of green LAI</p>},
	keywords = {LTER-KNZ, tallgrass prairie},
	doi = {10.1109/TGRS.1986.289590},
	author = {Asrar, G.A. and Kanemasu, E.T. and Miller, G.P. and Weiser, R.L.}
}
