Treesearch

Although the title of our plenary session speaks generally of ""development"", virtually all of our discussion (and that in the other two plenary sessions) dealt with the effect of forest practices. That emphasis is appropriate. Seventy percent of the State's utilizable streamflow comes from commercial forest lands. An additional 25 percent of the State's water comes from--often intermingled--brush, grass, and alpine lands. It is not surprising, therefore, that concerns about cumulative impacts concerns also focus on forested lands, and specifically upon activities relating to the harvestin...

Abstract - The hydraulic characteristics of flow through channels are an important component of fish habitat. Salmonids have evolved in stream systems in which water velocity and flow depth vary spatially within the watershed and temporally on a daily, seasonal, and annual basis. Flow requirements vary during different phases of the freshwater life cycle of salmonids: free passage is necessary during migration of adults; clean and stable gravel beds ensure successful incubation of eggs; and adequate velocity and depth of flow provide space for summer rearing and overwintering. The life...

Abstract - Pipeflow dynamics are being studied at Caspar Creek Experimental Watershed in north-coastal California near Ft. Bragg. Pipes have been observed at depths to 2 m within trenched swales and at the heads of gullied channels in small (0.8 to 2 ha) headwater drainages. Digital data loggers connected to pressure transducers monitor discharge using calibrated standpipes. During storms, pipeflow up to 8 l s-1 has been measured, while, within the same swales, no surface channel flow occurred. Pipeflow discharge has been correlated with antecedent precipitation

Abstract - Although experimental watershed studies have consistently shown that water yield can be increased by removing trees and shrubs, programs to increase water yield on an operational scale have consistently failed. Failure has been related to overstated goals and benefits, unrealistic assumptions, political naivete, and the emergence of new interest groups. There is every indication that management of vegetation for increased water yield will continue to be impractical

The fire program planner faces an increasingly complex task as diverse--and often contradictory--messages about objectives and constraints are received from political, administrative, budgetary, and social processes. Our principal challenge as we move into the 21st century is not one of looking for flashier technology to include in the planned fire program. Rather, we must give major attention to the development of a better, more effective understanding by politicians, administrators, and the general public of the fire program alternatives available, their risks, and their real social,...

Breeding bird communities were studied in 32 forest islands surrounded by urban development. These isolated woodlands in Springfield, Massachusetts, provided breeding habitats for a wider variety of birds (77 species) than previously described for other urban habitats (e.g. four times as many species as found in urban residential areas in the same city in a previous study). The size of the woodland was the primary influence on bird diversity in these wood-lands, explaining 79 and 75% of the variation in total species richness and the Shan- non-Weaver index of bird species diversity,...

Abstract - New understanding of how steepland channels formed is being pursued over a large range of scales, from entrainment of bed particles to the transfer of stored sediment down channel systems. Low submergence of bed particles during transport and wide heterogeneity in particle sizes strongly affect bedload transport. At the scale of a reach, scour-lobes are becoming widely recognized as common constructional units governing behavior of braided, meandering, and pool-riffle channels. Channel morphology and sediment transport can be radically altered by infrequent debris flows and...

Abstract - High-magnitude, low-frequency discharges are more responsible for transporting suspended sediment and forming channels in northwestern California than in previously studied areas. Bankfull discharge and the magnitude and frequency of suspended sediment discharge were determined at five gaging stations in northwestern California. Although discharges below which 50 percent of the suspended sediment was transported and discharges which transport the greatest suspended sediment (effective discharge) occurred relatively frequently, recurrence intervals for these discharges were...