Societal and Environmental Benefits

Salmonid recovery planning provides important benefits to human society. Restoration of salmonid habitat and the recovery of salmonid populations provide economic returns through increased salmon harvests and recreational tourism and non-economic returns in the form of ecosystem services. For example, restoration of stream corridors benefits both people and salmonids through sediment reduction and bank stabilization. Such ecosystem services have real economic value – as in the reduced dredging costs in ports or the increased value of property located adjacent to a healthier stream corridor – but these values are challenging to measure directly. This section will review one aspect of salmonid recovery planning – the restoration of stream corridors – as an example of the valuation of recovery planning.

Environmental benefits provided by stream corridors are discussed in detail in the Riparian Habitat section. By acting as "kidneys" for the watershed, stream ecosystems act to purify and store water. Intact riparian habitat also supports greater biodiversity, higher species density, and is more productive than most other ecosystems (Askey-Doran 1999).

Stream corridors provide many goods and services. Examples of goods provided by healthy stream ecosystems include fish and other game animals. Services provided by stream ecosystems include – but are not limited to – water purification, increased water holding capacity of soils, fish production, flood mitigation, stream bank stabilization, agricultural pest reduction, pollination, and air purification. Costanza et al. (1987) estimated that marine coastal ecosystems contribute $10.6 trillion per year worth of services to the global economy. The total contribution of all ecosystem services was found to be $33 trillion, or 1.8 times the 1997 global gross national product (GNP).

Water purification occurs when water runs off the surface or moves laterally below the surface. Riparian forests can decrease nitrogen concentrations in runoff by 90 percent and decrease phosphorous concentrations by 50 percent (ESA 2003). Excess nutrients are taken up by plants, algae, bacteria, and fish, absorbed into the soil, or rendered harmless by the process of denitrification. When runoff contains pesticides, some of these chemicals can be degraded by some of the thousands of species of bacteria that specialize in breaking down specific organic chemicals. Chemical reactions either reduce or oxidize heavy metals, which are then further processed by precipitation, adsorption by plants or soil, or filtration and sedimentation. On a larger scale, trees, shrubs, and plants (both standing and down), organic litter, woody debris, and uneven ground reduce stream turbidity by trapping some of the sediment before it enters the stream channel (Ecological Society of America 2003; Eubanks 2002; Askey-Doran et al. 1999).

Soil water retention capacity is influenced by plant and animal activity. The large amounts of litter, large and small woody debris, and standing biomass in stream corridors provide the fodder for future soil. Bacteria and other organisms in riparian forests degrade organic matter into food for smaller creatures, plants, or aquatic life. The large amount of organic material in the soil allows the soil readily to absorb and retain moisture. Infiltration rates 10–15 times higher than grass turf and 40 times higher than a plowed field are common in forested areas (SAFCA 2003).

When floods occur, a naturally functioning riparian corridor slows water flow and provides for the storage of some excess water. Trees and plants provide an uneven surface – slowing the water through friction. Herbaceous plants with flexible stems lay flat against the ground during high flows, protecting the soil from erosion. By increasing the channel roughness of the stream banks, stream corridors reduce near bank velocity of water flow. Through these services, stream ecosystems reduce the impacts of high water flow on nearby natural and human ecosystems.

Root structures of trees, shrubs, and herbaceous plants make up an interwoven structure that holds soil together and stabilizes banks. During periods of standing water, trees adapted to stream ecosystems survive anoxic root conditions and maintain a stable structure for the soil. Non-riparian plants literally suffocate in standing water due to lack of oxygen and are often unstable when the soil is soggy.

When located near agricultural areas, riparian vegetation may play a role in integrated pest management. Cavity nesting riparian bird species such as kestrels and owls prey on rodents in vineyards. Other cavity nesting birds including wrens, tree swallows, oak titmice, and bluebirds can help reduce populations of pest insects. Bobcats, coyotes. and foxes also emerge from riparian areas to prey on rodents.

Fishermen enjoy coastal resources in February, 2004 on the Santa Cruz Wharf.

Other services provided by stream ecosystems include pollination, air purification, and the fixation of solar energy to produce food and raw materials. Like the services described above, these services provide specific benefits for human communities, are often costly to replicate, and are so ubiquitous that their value is often overlooked. There are still many unanswered questions about ecosystem services. For example, what are the tradeoffs between different services? What is the role of biodiversity? What are the effects of both long- and short-term perturbations to different ecosystems and the services they provide? These and other questions must be investigated better to define and integrate the relationships between the economic system that we use with the natural ecosystems upon which we depend.

In San Mateo and Santa Cruz Counties, the aesthetic and recreational benefits of stream ecosystems are obvious to even a casual observer. Stream ecosystems provide opportunities to fish, canoe or kayak, swim, hike, picnic, photograph, paint, or engage in other recreational activities. Additionally, stream corridors serve as inspiration and provide scenic beauty. The recreational tourism industry is dependent upon the recreational opportunities and aesthetic enjoyment provided by stream corridors. In Santa Cruz County and to a lesser extent, San Mateo County, nature-based tourism and recreation is an important industry that supports a host of other service industries such as the hospitality industry, recreational gear and supply providers, and gasoline service stations (see the Resource Use section for more information).

References

Askey-Doran, M., N. Pettit, L. Robins, and T. McDonald. 1999. The Role of Vegetation in Riparian Management. In Riparian Land Management Technical Guidelines, edited by S. Lovett and P. Price. Canberra: LWRRDC.

Costanza, R., R. d'Arge, R. de Groot, S. Farber, M. Grasso, B. Hannon, K. Limburg, S. Naeem, R.V. O'Neill, J. Paruelo, R.G. Raskin, P. Sutton, and M. van den Belt. 1987. The value of the world's ecosystem services and natural capital. Nature 387(6230):253-260. View on-line source.

Ecological Society of America. 2003. Communicating Ecosystem Services [Web site]. ESA [cited January 10, 2004]. View on-line source.

Eubanks, C.E. 2002. "A Soil Bioengineering Guide for Streambank and Lakeshore Stabilization." U.S. Department of Agriculture, Forest Service. FS-683. View on-line source.

Sacramento Area Flood Control Agency (SAFCA). 2003. Environmental Efforts [Web page] [cited January 8, 2004]. View on-line source.

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