SU0013248 - Laserfiche WebLink

Home Browse Search

Vegetation The project area has been disturbed by agricultural development south of the Mokelumne River and past quarry operations north of the river; however, the area still contains a variety of plant communities and species assemblages composed of native and naturalized/introduced plants. The proposed quarry site is cultivated in asparagus and walnut crops. Because of the intensive agricultural use in the proposed quarry area, other vegetation is primarily limited to weeds, grasses and herbs. The Mokelumne River is flanked on both sides by a corridor of riparian vegetation. The riparian zone ends abruptly at the existing quarry site to the north and agricultural land to the south. The river channel has been straightened for flood control and what remains is a linear corridor of mature riparian woodland. The proposed bridge relocation site supports a diversity of ruderal grassland and riparian vegetation. Prior to agricultural and quarry development, the region's natural riparian vegetation likely consisted of a mix of riparian communities including Great Valley Cottonwood Riparian Forest, Great Valley Mixed Riparian Forest, and Great Valley- Valley Oak Riparian Forest (Holland, 1986). In presettlement times, the riparian zone was likely flanked by Valley Needlegrass Grassland. Currently, remnants of the natural riparian forest remains along the banks of the Mokelumne River. Dominant woody riparian species include valley oak, cottonwood, willow, alder, walnut and interior live oak. There are no areas of completely pristine native vegetation in the project area. There are, however, isolated areas dominated by native species.. Existing vegetation within the project area has a patchy distribution, with some recently disturbed areas remaining unvegetated and other, less disturbed areas supporting dense thickets of shrubs and herbaceous plants. Plant Assemblages Five basic plant assemblages were identified within the study area. These can be described as: 1) ruderal herbaceous vegetation with no overstory; 2) Oak dominated savannas; 3) riparian woodland-dominated overstory; 4) disturbed scrub; 5) and emergent freshwater marsh. These plant assemblages are mapped in Figure 3.3-1 and brief 39