| Abstract: | Empirical evidence from a semiarid watershed of the southwestern United States (Verde River basin, Arizona) indicated that abundance and species richness of mixed deciduous riparian forests varied in a curvilinear and quantifiable fashion as a function of stream flow parameters. Three indicators of riparian abundance—foliage area, stem basal area and stand width—increased most significantly with growing season flow volume, a surrogate indicator of riparian water availability. Tree species richness varied in a bell curve fashion with flood size, with the greatest richness occurring at streams with intermediate flood magnitudes. These instream flow models have management implications for riparian habitats. They suggest that flow volume (and the related attributes of water-table recharge and floodplain soil wetting) is the primary factor regulating riparian vegetation abundance in the Verde River watershed, and provide a first approximation of the extent of riparian loss expected from flow diversion or other types of flow reduction. |
