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Show 43 The texture of the sandy‘mounéslthe elevationffbozegthegplzy}2;» soils and seasonal flooding of the flats along withflpickleweed appeared to be the major regulatory factors éégnagtingfthéseitwgspeciestjf/a Twé rodentStewénhabfi$1this community. Vegetated pgng Community. This community figures Very prominently in the economy of the biota of the study area. Here are found the greatest variety of plants and the largest populations" and the greatest kinds of animals of any of the valley floor communities. typical appearance of this community is shown in Fig. 6. The In the backs _ground, the higher portions of the dune has taller shrubs and conspicuous barren sandy areas between these plants. This area of the dunes has a 'nasg'dkstinctive plant and rodent population. In the foreground is a hummocky area bagdénaégafhe duée which is composed mostly of grasses and smaller shrubs which also has a dinstinctive plant and rodent population. The soils of the former are sands, while the soils of the latter are sandy loams and sandyclay loams formed from a combination of dune sands and \soil particles of adjacent clay flats. The irregular shape, sharp‘ changes in relief, and the varied flora of the dunes form a ébnspicuous contrast to the plain-like relief of the other communities of the valley floors, forming sharp boundaries and narrow ecotones. There are several stages of succession in the stabilization of the active dunes by vegetation. late ioneer plant§1first appear in the swales and ridges of the dudaare scurf pea, Psoralea lanceolata Pursh. , and buckwheat, Eriogonm dgpigm Stokes, respectively. Between the dunes the former appears in almost solid green masse53inmthe-ereee. This plant has ‘ extensive underground stems that are well adapted to the shifting 'W‘MW sands: ofteéggzggths may ggfexposed.h The‘buckwheat may become three fett tall on the ridges and is |
