Tongass National Forest

The Forest Plan Riparian Standards and Guidelines provide guidance for stream buffers when considering timber harvest. The buffers vary depending on the stream process group. All process groups include the concept of managing adjacent areas to provide for a reasonable assurance of windfirmness to the buffers. The High Gradient Contained process group, which includes v-notches, says to buffer 100 feet or to the top of the slope break, which ever is longer, and an additional distance if needed to provide a reasonable assurance of wind firmness. This process group standards and guidelines specifically remind us that the Riparian Management Area can be changed to better reflect on site situations following a watershed analysis as guided by Appendix J of the Plan. These Standards and Guidelines also notes that it was anticipated about 25% of the high gradient contained Class III streams Riparian Management Areas would be changed to better reflect on site conditions.

Blow down in steep V-notches can introduce sediment into the streams (by uprooting trees and displacing soil) which may be viewed as being worse than cutting the trees. However, maintaining the source for wood recruitment into these v-notches may be a more important concern than small sediment inputs associated with windthrow. Wood has a primary role in sediment retention in v-notches, and functions to create sediment traps. In cases where specialists determine that short term increases in sediment are a larger concern than long term sediment retention, they may take solace in the flexibility that is already built in to the Forest Plan Standards and Guidelines (i.e. adjustment to process group Standards and Guidelines can be made if the objectives for the process group can still be met). (See concern related to windfirmness of riparian buffers [04-18].)

Applying the reasonable assurance of windfirmness to all Class III buffers as currently included in the Plan may not be a good blanket approach. For example, if the intent is primarily to provide short and long term sources of large woody debris, trees that do not reach the stream may not be necessary to meet this intent. Given that these streams are generally quite small and that if buffers do blow down, the period of time before this wood deteriorates to the point of not being effective (several decades), trees of sufficient size will have grown and could provide suitable replacement sources of large woody debris. Consideration should be given to adjusting the Forest Plan Class III stream buffer Standards and Guidelines in relation to the reasonable assurance of windfirmness requirements. For example, it may be better to not require a reasonable assurance of windfirmness for Class III buffers except when other resource values or needs are part of the buffer considerations. If the Class III buffers are included as part of a harvest retention zone such as an area retained to meet goshawk or marten Standards and Guidelines, a reasonable assurance of wind firmness is a key consideration in the prescription for the retention.

There is a perception that some project decisions in heavily managed watersheds could have been stronger if they had incorporated a “harder” look at watershed issues through even a simple, low-intensity watershed analysis preceding or concurrent with NEPA. Public comments on draft NEPA documents frequently question why watershed analysis was not completed for heavily managed watersheds.

NEPA reviews have suggested planning record documentation of decisions NOT to conduct watershed analysis (for reasons according to Appendix J). Alternatively, planning records could document appropriate elements and findings of resource reports that address Appendix J criteria and provide “watershed analysis” products that support the NEPA decision. In some cases it may be appropriate to organize a watershed analysis from relevant sections of resource reports. In other words, in many cases the “watershed analysis” does not have to be a stand-alone process requiring intensive, time-consuming effort. But it can and should be considered a relevant process to focus NEPA analysis on key watershed issues.

There is sufficient existing guidance in Appendix J, combined with the draft R10 Watershed Analysis Handbook (July 1997).

Using information from ongoing studies and monitoring of riparian buffers and associated wind firmness assess how Class III buffers are being prescribed and applied in relation to the Class III standards and guidelines. Particular attention should be given to the use of the watershed analysis tools outlined in Appendix J of the Plan to better meet on-site objectives. Also assess the need to adjust the reasonable assurance of windfirmness requirements in the Class III Standards and Guidelines.

• Forest Hydrologist
• Forest Planner
• District Ranger

• Assessment report with recommendations