Principle – CCFM 3.0 Conservation of Soil and Water Resources

Criterion- CCFM 3.1 Physical environmental factors.

Indicator - CCFM 3.1.4 Trends and timing of events in stream flows from forest catchments.

Box B: Definition:

"Increased streamflow after harvesting can be attributed to less biological demand and reduced evapotranspiration, due to a smaller foliage surface area. Return of the streamflow to near background levels usually takes at least 20 years, depending on the height and complexity of the forest canopy. Site conditions vary considerably within and between forest ecosystems and across ecoregions. …

Care must be exercised in separating the impacts of forest practices from those of other industrial, recreational, agricultural and urban activities. This may be achieved by stratifying the data to include only those streams in which changes can be attributed directly to such forestry activities as harvesting or road building." (CCFM pp.51-52)

Box D: Applicability to Different Landowners. Explain any differences:

Scale and availability of measurements may preclude some small landowners from using. Measurements may not be available for the watershed they are in.

Box E: Overlap:

CIFOR 2.2.3 Canopy opening is minimized (Opening effects trends and timing of snowmelt)

CCFM 3.1.2 Area of forest converted to non-forest land use

Notes:

Timing and trends are both predictive and diagnostic as changes indicate a deviation from historical patterns (diagnostic) and suggest a new pattern (predictive) for future events. However they must be considered in the context of climate and other land use changes depending on the scale of the watershed in question. It is more easily applied in relatively small watersheds because larger watersheds have more chance of factors effecting the water timing and trends than just forestry practices.

Notes:

It falls into two categories as it is part of the basic hydrologic cycle and processes of an area but changes from the historical record may indicate perturbation(s) or an ecosystem response to perturbation(s).

Box I: Underlying Concepts:

"The sustainability of aquatic and riparian ecological systems is strongly tied to the dynamics of the streamflow regime. Timber harvest can influence the flow regime by increasing total flow, altering peak discharge rate, and changing the duration of flows of differing frequency of occurrence. These changes in the energy and sediment transporting capability of the fluvial system can cause an alteration in both channel morphology and aquatic habitat. Depending on the practices used, timber harvest can increase the rate of sediment introduction to the channel system, thus further confounding the energy/transport relationship." Troendle and Olsen, 1993.

"Implications of altered streamflow regimes are important for assessing the future ecological integrity of stream ecosystems subject to large-scale timber harvest and other disturbances that remove a substantial proportion of the forest cover." Burton, 1997.

The indicator requires long-term trends and deviation from those trends to have the best indicator value. In many instances streambank stability and stream structure is used in some areas as a surrogate estimate of differences in streamflow timing and flood events. However, these estimates are not universally applied.

To document changes in trends and timing of stream flows from forest catchements requires "… special guaging, statistical controls and many years of data collection are necessary before any downstream increases can be verified." Burton, 1997.

Factors such as wildfire have similar or even more drastic changes in timing of events and trends for watersheds than do most harvest practices. Local experience in this vein is both recent and drastic in the study area. Flood damage is common after intense fire events because the timing and trends of flows are altered.

The indicator is intuitively strongly appealing but current limitations in available data and methodologies make it difficult to apply.

Box J: Relevance to Sustainable/Unsustainable Management:

It is highly relevant but not really an operational indicator as indicated by the CCFM report.

Box K: Measurement Methods:

"Methodologies for collecting national data on the trends and timing of events in stream flows from forest catchments are at the early stages of development." CCFM p. 51.

Paired watersheds are the best method to determine changes in streamflows and timing from forest management practices. One is maintained and monitored as a control and the other is the treatment area. Such studies are few and tend to be limited to small, experimental watersheds. There is potential merit in modeling the results from the few, and widely scattered studies of paired watersheds to estimate the effects of various treatments to watersheds.

Locally, the models are more rule-of-thumb based on local studies. Reduction of existing tree canopy by 20-23% results in measurable differences in peak flows and timing. Changes in canopy cover of 30% show measurable changes in base flows. Locally the concept of "Equivalent Clearcut Area is applied to watersheds using the local Silver Creek/Horse Creek studies.

Box L: Data Required:

Long-term streamflow measurements are required. This includes a sufficiently long period of time of measurements before the treatments take place, then the long-term monitoring afterwards. Burton, 1997, used 10 years prior to treatment and then traced results for 20 years after treatment. Such long-term studies are rare; so modeling seems the best approach. The existing studies provide the base information for the study. The model uses more widely available vegetation cover changes (perhaps as gathered by remote sensing) to estimate changes in timing and amounts.

Streamflow measurements are not available for all streams and watersheds. In some instances there are less measurements taking place now than in previous years. For example the 1988 Payette N.F. Plan listed 14 stream gage sites. In 1996, only 7 of the 14 were still in operation.

Box M: Data Used for the North American Test:

Burton, 1997, was used as the example of test data.

Payette National Forest Eight-Year Monitoring Report, July 1996

Box N: Example Results:

Use Fig. 5 from Burton, 1997.

Box O: Assessing the Practicality :

If suitable models can be produced; then it may be a practical indicator. It is not currently practical as noted in the CCFM publication. If paired watershed studies are required; then it would be impractical for most areas.

Box P: Assessing the Information Value;

The information value is high as it directly relates to watershed events (amounts, timing, etc.) with good predictive value for downstream areas.

Box Q: Overall assessment:

Reject.

Reject the indicator because of the current limitations in data and methods.

Box R: Did you rewrite or revise to a new indicator. If so what?

No, the indicator is clear as written.

Box S: References:

• Burton, Timothy A. 1998. Fisheries Program Leader, Boise National Forest. Personal communication. June 29, 1998 and July 8, 1998.
• Burton, T.A. 1997. Effects of Basin-Scale Timber Harvest on Water Yield and Peak Streamflow. Journal of the American Water Resources Association. Vol. 33, No. 6, pp. 1187-1196.
• Canadian Council of Forest Ministers. 1996. Criteria and Indicators of Sustainable Forest Management in Canada, Technical Report. Natural Resources Canada. Canadian Forest Service, Cat. Fo75-3/6-1997E. Ottawa ON. 138 p.
• Hardy, T. Hydrologist, Boise National Forest. Personal communication. July 8, 1998.
• Idaho Department of Lands. 1996. Best Management Practices; Forest Stewardship Guidelines for Water Quality. Idaho Department of Lands, Coeur d’Alene, Id. 33 p.
• King, J.C. 1998. Scientist, Snake River Adjudication, Boise Adjudication Team. Boise, Idaho. Personal communication. June 29, 1998.
• King, J.C. 1994. Streamflow and Sediment Yield Responses to Forest Practices in North Idaho. In: Proceedings of Interior Cedar-hemlock-white Pine Forests: Ecology and Management, Washington State University, Pullman, Wa.
• Payette National Forest – Eight-year Monitoring Report. 1996. United States Department of Agriculture. Forest Service, Intermountain Region, 213 p.
• Troendle, C.A. and W.K. Olsen. 1993. Potential Effects of Timber Harvest and Water Management on Streamflow Dynamics and Sediment Transport. In: Covington, W.W. and Debano, L.F., Technical Coordinators. 1994. Sustainable Ecological Systems: Implementing an Ecological Approach to Land Management. Gen. Tech. Rep. RM-247. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station.

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