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<br />Parameters monitored in the terrestrial environment are those deemed important for bank <br />stabilization. aquatic and terrestrial faunal habitats. tribal botanical resource, and recreation. Prior <br />to 2002. vegetation type, area, and height were mapped annually at 11 sites (river miles. 6. 43.5. <br />50.5,55.68.5.71.5.93. 123. 194.209. and 243) using aerial photographs and field studies. In <br />addition. downslope growth rates of equisetum. juncus. and phragmites were measured along <br />selected transects on a monthly basis over a four-month period. The monthly field studies also <br />monitored growth or removal of exotic plants. such as tamarix ramosissima and alhagi <br />camelorum (camelthorn). and sample low-elevation areas for changes in seed abundance and <br />type. Surveys now consist mostly of random samples throughout the CRE and of culturally <br />significant plants (exotic/invasive species and ethnobotanical species) during April. May, and <br />September. Vegetation of interest includes acacia, equisetum/sedge, redbud (Cercis occidentalis). <br />tamarix (tamarix ramosissima). arrowweed (tessaria sericea), bermuda and red brome monotypic <br />grasses, hackberry (celtis reticulata). cliffrose, desert brome. mesquite. coyote willow (salix <br />exigua), baccharis seepwillow (baccharis emoryi and salicifolia). Before 2000, photographic <br />prints were used to manually trace the distribution of vegetation species. based on a visual <br />interpretation ofCIR color and texture. All derived polygons were then field checked. The <br />collection of orthorectified imagery now makes this process more efficient and accurate. More <br />advanced remote-sensing data and analysis methods should be able to increase the area covered <br />and reduce the time required for field surveys, but this will depend on the capahility of the <br />remote-sensing data that can be acquired for the CRE within GCMRC's remote-sensing budget. <br /> <br />Several factors control the spectral retlectance ofvegelalion; lhese include water, <br />chlorophyll a (absorbs at 0.430 I'm and 0.662 "m) and b (absorbs at 0.453 "m and 0.642 "m), <br />assessory pigments (e.g., Beta carotene and Iycopene that absorb between 0.460 "m and 0.550 <br />Itm), nitrogen. lignin (cell wall polymer), cellulose (40-60% of cell walls), and open pore space. <br />Numerous studies have been performed over the past three decades to determine the most <br />appropriate data and analysis methods to accurately detect and map these vegetation <br />characteristics using remotely sensed data. Recent research has determined the following <br />relations. <br /> <br />I. There is a strong linear correlation between chlorophyll (a+b) and (I) the ratios 0.750 <br />"m/0.700 "m and 0.750 Itm/0.550 "m and the green vegetation index (Gitelson and <br />Merzlyak, 1997); (2) the 0.700 11m and 0.735 "m retlectance and their band ratio <br />(Gitelson et aI., 1999); (3) the first derivative of the green vegetation index (Elvidge and <br />Chen, 1995); (4) the perpendicular vegetation index (Richardson and Wiegand, 1997); (5) <br />the first derivative of the 0.721 1,m band (Blackburn, 1999); and (6) the band ratios 0.836 <br />"m/0.817 "m and 0.969 "m/0.93I "m, the first derivative of the 0.750 "m band, and the <br />second derivative of the 0.753 "m band (Blackburn and Steele, 1999). Blackburn and <br />Steele (1999) also found good correlations between their wavelength band ratios and <br />derivatives and the carotenoid content and that the derivative of 0.72 I "m band correlated <br />well with lolal chlorophyll, chlorophyll a. and chlorophyll b, but not so well with <br />carotenoid content. <br /> <br />2. Penuelas et al. (1997) found some correlation between the 0.900 "m/0.970 1,m band <br />ratio and plant water content. but it was very weak. but Hardy and Burgan (1999) found a <br />good correlation between NDVI alld plant moisture. <br /> <br />3. Kokaly and Clark (1999) found good correlations between spectral rellectance <br />centered at 1.730 "m, 2.100 "m, and 2.300 "m with nitrogen and cellulose. but not withlignin. <br /> <br />14 <br />