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• • VEGETATION <br />This irrigated pasture can only be maintained by irrigation. The water table is from four to six feet <br />below the surface and therefore not close enough to maintain the pasture without irrigation. Most of the <br />land in the eastern part of the operation area is occupied by a grass dominated pasture. Portions of the <br />western part of the operation area seem to be more strongly dominated by alfalfa. Historically, these <br />pastures are cut for hay a couple of times a year, perhaps three times in good years. <br />Farmyard: The Farmyard unit is heavily disturbed, containing vegetation mainly composed of weeds, <br />escaped individuals from adjacent lands, vegetable and flower gardens, or no vegetation at all. This unit is <br />of very little importance to the overall vegetation of the site. But in the revegetation could become a <br />significant source of weeds that could affect the quality of the revegetation products. <br />Natural Vegetation <br />Riparian Forests: The riparian forests of this area fall into two primary categories. Their distinction <br />is mainly based on the density of the vegetation. The density of the vegetation, in turn, appears to be <br />dependent mainly upon two factors -the historical origin of the specific vegetation and the relationship of <br />the unit to the groundwater hydrology. However, the maturity of the arboreal portion also con[ributes to <br />the character of the vegetation. <br />Dense: The dense forest areas exhibit high density for two primary reasons. First is the <br />relationship of the vegetation to the groundwater. The closer the surface is to the groundwater the higher <br />the density of forest vegetation supported. However, there also appears to be a limit in that if the <br />groundwater is too close to the surface the land cannot support much tree growth. In those situations, the <br />forest is replaced by a shrub dominance and heavy growths of hydrophytes. <br />The density of these units is great enough that the canopy achieves nearly 100% closure. Few areas <br />exhibit significant openings in the canopy and the uniform topography and light distribution on the forest <br />floor tends to create a very uniform understory composed of mainly grasses and shade-loving shrubs. At <br />ground level the woody vegetation, primarily the trees, have a somewhat open appearance presenting what <br />is often referred to as a cathedral forest. <br />In genera], these dense canopied forests with a fairly open forest floor are occupied by older trees, <br />probably in the 50 to 70 year range. The uniform distribution and relatively large diameter of the trunks <br />indicates a mature growth at near peak development. Characteristically, however, cottonwood forests at <br />this stage tend to also be on the verge of the normal rapid decline in vitality. This pattern is due to the trees <br />being nearly all of the same age. Furthermore, replacement of adults does not readily occur in such forests <br />as cottonwood usually regenerates by seed and often requires scouring floods to do so. <br />Another form of dense riparian forest found on the site, but not commonly, is the thick, young <br />cottonwood forest. Such a forest growth was a major part of the Great Blue Heron site. On this site, such <br />young growths are rare, small, and highly localized to low elevation ground near the river. These forests <br />are characterized by virtually no understory and a very high density growth of even aged cottonwood trees <br />with trunk diameters up to about 8 inches. This forest type appears to be the early stages in the <br />development of the more mature forest described above. However, continued disturbance from flooding <br />can potentially maintain this growth form for very long times. <br />Grisenti Farms Gravel Pit Original Application Exhibit J Page J-2 <br />