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4.7 BIOLOGICAL RESOURCES a jungle-like appearance to this classic remnant of valley riparian woodland. Only a few other preserved mature riparian woodland segments, such as Caswell State Park in southern San Joaquin County,equal that present along the Mokelumne River in Brovelli Woods. Valley Grassland The non-wooded areas of the project site originally supported a complex of bunch grass species. After a century of heavy grazing, these have been replaced by a wide variety of introduced grass and forb species such as wild oat (Avenafatua),Italian rye (Lolium multiflorum), ripgut brome (Bromus mollis), filaree (Erodium malacoides),wild mustard (Brassica sp.), and wild radish (Raphanussp). Presently, grazing pressure appears only moderate,and in some areas a relatively thick grass mat has formed which in turn promotes many grassland rodent species. Invertebrates, Fish and Wildlife Invertebrates Among the thousands of invertebrate species that occupy the project site, two species whose geographic ranges include this area are becoming very scarce. One is the federal-listed threatened valley elderberry longhorn beetle (Desmocerus californicus dimorphus). This is one of the numerous host plant specific insects whose larva, a large grub, feeds only on elderberry bushes. These larva eat the soft pulp of the elderberry cane and after metamorphosing emerge as adults through relatively large holes in the bush stems. Although the winged adults or burrowing larva may occasionally be located, it is the presence of the adult emergence holes which is the most reliable indicator of this species' presence in an elderberry stand. An examination of randomly selected branches of each large elderberry bush encountered in the late spring survey of the riparian portion of Brovelli Woods did not reveal any of these holes. The vernal pool fairy shrimp(Branchinecta lynchi)is presently under consideration for federal protective listing. They are larger than most zooplankton species and easy to differentiate from common freshwater species such as daphnia or cyclops because of their miniature shrimp-like appearance and their characteristic of swimming on their backs with appendages extended towards the water surface. Weekly hauls between March 15 and May 15, 1992, with a ##20 mesh plankton net through the deeper portions of the project site's vernal pools produced no invertebrates exhibiting these characteristics. Another invertebrate species presently under consideration for protection,the curved-footHygrotus diving beetle (Hygortus curvipes), also prefers natural pond and spring pool conditions. However, the only aquatic beetle species collected in the plankton net and fine mesh seine samples was the water boatman, a very distinct beetle with enormous swimming appendages. 4.7-11