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<br />002';93 <br /> <br />Linkages associated with riparian plant communities, insectivorous birds, perigrine <br />falcons have been established. Passerine birds increase in number and diversity when riparian <br />vegetation becomes more productive in March and into early Summer. <br /> <br />When does primary breeding season start for riparian avifauna? <br />When do young birds fledge? <br /> <br />Are terrestrial or aquatic insects primary food sources? <br />Are GC birds more seed eaters or insectivores? <br /> <br />What are the birds besides SWWF that should be of concern for months January to July? <br /> <br />Marsh and Riparian Vegetation. <br /> <br />Marsh and riparian vegetation has increased in abundance since the closure of Glen <br />Canyon Dam. The regulated flows have resulted in a more stable environment for marsh and <br />shoreline vegetation to become established and expand. The riparian communities are <br />represented by woody plants such as Tamarix chinensis, Pluchea sericea (arrowweed), Baccharis <br />spp., Prosopis glandulosa (mesquite), Salix, goodiingii (Goodings Willow), S. exigua (Coyote <br />Willow), Solidago sp. (Goldenrod) and annual and perennial grasses and forbes (e.g., Stanleya <br />pinnata- princess plume, Salsola iberica- tumbleweed, Schizachrium scoparium-little bluestem). <br />The marsh communities are represented by Equisetum (horestails), Carex aquatilis, Juncus spp, <br />Scirpus spp. (sedges and rushes), Phragrnites australis (reed), and Typha domingensis (cattails). <br />The location of these plants relative to the shoreline is dependent on each species water <br />requirement and ability to withstand innudation and dewatering. <br /> <br />Short-term changes in dam operations can affect long term responses to the riparian <br />community. Small fluctuations may enhance sediment accumulation in marsh areas. The build up <br />of sediment alters water relations/availability and may encourage expansion of drier adapted <br />plant species to damp-soil conditions vs wet conditions. Higher discharge events promote <br />scouring and may return an area to a marsh condition or bare sand. The 1996 high flow event had <br />the effect of burying vegetation, rather than scouring. Vegetation closest to the river and at low <br />elevation experience the greatest effects/damage. Most obvious damage is associated with areas <br />upstream of reattachment bars and near the banks of debris fans, both areas are associated with <br />eddy current patterns. <br /> <br />Total foliar cover was lost as a result of the flood, particularly in reaches below Marble <br />Canyon, but no sites showed a significant change in area covered by wetland vegetation (Ayers <br />and Kearsley 1996). Low growing (0.0-0.3 m), perhaps transitional plant species (e.g., broad <br />leafed herbs, and grasses) that occupy damp-soil environments may be most susceptible to short <br />duration high flows. These plants may sustain damage via burial (Ayers and Kearsley 1996). <br /> <br />Distribution of surface organic material occurs with high flows that may contribute to <br />downstream drift, or local redistribution of organics. The redistribution of organics and shifting <br />of sands associated with high flows may contribute to increased marsh plant densities. An <br />increase in the density of some marsh species (e.g., cattails) was noted in lower reaches of Grand <br />Canyon following the flood (Ayers and Kearsley 1996). However, this may be a result of the <br />