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A cumulative watershed effect (CWE) is any response to multiple land-use activities that is caused by, or results in, altered watershed function. The CWE issue is politically defined, as is the significance of particular impacts. But the processes generating CWEs are the traditional focus of geomorphology and ecology, and have thus been studied for decades. The CWE issue is complicated by the variety of land-use activities which cause impacts, and by the multitude of philosophical and economic values impacted.

In 1984 – 1987 the recovery of riparian willows (Salix spp.) and sycamores (Platanus racemosa) was studied on two short, intermittent stream sections in a newly acquired portion of Henry W. Coe State Park in central California. Prior to removal of cattle in 1983, the plots contained mature sycamores, one young sycamore, and five willows. By 1985 over 320 willows, 16 sycamores and 1 cottonwood (Populus fremontii) had appeared, and basal sprouts had developed on the mature sycamores. Young willows and sycamores grew slowly, and establishment and growth generally ceased as surface flows...

Protecting riparian habitat from livestock grazing on private land is a complex task that requires paying attention to sociological and economic as well as physical and biological factors. Six livestock exclusion fencing projects on private property in northwestern California are described. The importance of long term maintenance and the need for landowner incentives are discussed. Significant gains may be made via a statewide, coordinated effort to encourage the protection of riparian habitat on private property.

Due primarily to alteration of riparian vegetation and nest parasitism by brown-headed cowbirds (Molothrus ater), the least Bell's vireo (Vireo bellii pusillus) has under-gone a tremendous decline in range and numbers since the 1920's. In 1987, we sampled vegetation at 32 nest sites to characterize nesting habitat of least Bell's vireos in the Santa Ynez River drainage. Most next (59.4%) were located in willows (Salix spp.) or mugwort (Artemisia douglasiana) at heights of less than 1 m. Vireos selected sites with relatively dense vegetative cover in the vicinity of the nests. Herbaceous...

Managing and restoring watersheds often involves recreation of riparian habitats. The natural functions of riparian forest natural to slow flood water, stabilize stream banks and trap sediments can be used in restoring disturbed creek systems. The State Coastal Conservancy's wetland enhancement program is preserving wetlands on the California coast through repair and management of watersheds. Examples from rural and urban areas illustrate how riparian restoration can be integrated into watershed projects.

After the Wheeler Fire in southern California in July 1985, we monitored sediment deposition and vegetation recovery in a section of the severely burned chaparral riparian zone of the North Fork of Matilija Creek, near Ojai, California. Increased runoff was accompanied by low magnitude debris flows and fluvial transport of gravel, most of which was added to the channel and nearby hillslopes by post-fire dry ravel. The preburn riparian forest was dominated by white alder, California sycamore, and coast live oak. Regeneration of these species was entirely by resprouting, due to the absence...

Incubating salmonid eggs in streambeds are often threatened by deposition of fine sediment within the gravel. To relate sedimentation of spawning gravel beds to sediment transport, infiltration of fine sediment (

Certain floodplain systems in southern California sustain a unique scrub vegetation rather than riparian woodlands due to a lack of perennial water. Alluvial scrub occurs on outwash fans and riverine deposits along the coastal side of major mountains of southern California. This vegetation type is adapted to severe floods and erosion, nutrient-poor substrates, and the presence of subsurface moisture. Ten major stands were sampled by line intercepts to determine their species composition, community structure, and successional status. Plant ecology and successional dynamics of these stands...

Constituent loads in small streams are often estimated poorly. This is especially true for discharge-related constituents like sediment, since their flux is highly variable and mainly occurs during infrequent high-flow events. One reason for low-quality estimates is that most prevailing data collection methods ignore sampling probabilities and only partly account for variations in constituent flow