OAR 629-642-0600
Alternative Vegetation Retention Prescriptions
(1)
Alternative prescriptions are intended to apply to situations where the existing streamside stand is too sparse or contains too few live conifers to maintain fish, wildlife, and water quality resources over time. Future desired streamside stand conditions are achieved through immediate manipulation of vegetation, including reforesting the riparian management area with conifers.(2)
Sections (3) and (4) of this rule are alternative vegetation retention prescriptions that operators may apply if the conifer basal area in the riparian management area is no more than one-half of the standard target indicated in either Table 2 of OAR 629-642-0100 (General Vegetation Retention Prescription for Type F Streams) or Table 8 of OAR 629-642-0400 (General Vegetation Retention Prescription for Type D and Type N Streams), as may be applicable, and conditions described in the alternative prescription are applicable.(3)
Alternative Vegetation Retention Prescription 1 (Catastrophic Events). This alternative prescription applies to streamside stands that have been damaged by wildfire or by catastrophic windthrow, insect or disease mortality. Such mortality must occur at the stand level and shall not include normal endemic mortality. The prescription is intended to provide adequate stream shade, woody debris, and bank stability for the future while creating conditions in the streamside area that will result in quick establishment of a new and healthy stand. Operators shall:(a)
Retain trees that have fallen in the stream. Only portions of these trees that are outside the high water levels and do not contribute to the ability of the downed tree to withstand movement during high flows may be harvested.(b)
Retain all live and dead trees within 20 feet of the high water level of large and medium streams and 10 feet of the high water level of small streams.(c)
For Type F streams, retain live trees, dying or recently dead trees, and downed logs sufficient to satisfy the active management target shown in Table 2.(d)
For Type D and N streams, retain live trees, dying or recently dead trees, or downed logs sufficient to satisfy the standard target shown in Table 8.(e)
Live conifers shall be retained first to meet the target. If live conifers are too few to satisfy the target, then the target shall be met as much as possible by including windthrown trees within the channel and dying or recently dead trees.(f)
For purposes of this prescription the basal area of a windthrown tree in the channel or a retained dying or recently dead tree contributes two times its basal area toward meeting the target.(4)
Alternative Vegetation Retention Prescription 2 (Hardwood Dominated Sites). This alternative prescription applies to streamside sites that are capable of growing conifers, and where conifer stocking is currently low and unlikely to improve in a “timely manner” because of competition from hardwoods and brush. If portions of such riparian management areas currently contain abundant conifer basal area, it is intended that these areas of good conifer basal area be segregated and managed using the general vegetation retention prescription while the remainder is managed according to this alternative prescription. The alternative prescription is intended to provide adequate stream shade, some woody debris, and bank stability for the future while creating conditions in the streamside area that will result in quick establishment of a conifer stand. The operator shall:(a)
Evaluate the stand within the riparian management area and, where they exist, segregate segments (200 feet or more in length) that are well-stocked with conifer, as identified from an aerial photograph, from the ground or through other appropriate means. The general vegetation retention prescription for vegetation retention shall be applied to these segments.(b)
For the remaining portion of the riparian management area that has lower conifer basal area, the riparian management area shall be divided into conversion blocks and retention blocks.(c)
No more than half of the total stream length in the harvest unit can be included within conversion blocks. Conversion blocks can be no more than 500 feet long and must be separated from each other by at least 200 feet of retention block or by at least a 200-foot segment where the general vegetation retention prescription is applied.(d)
Within conversion blocks the operator shall retain:(A)
All trees growing in the stream or within 10 feet of the high water level of the stream.(B)
All trees leaning over the channel within 20 feet of the high water level of large streams.(e)
Within retention blocks the operator shall retain:(A)
For large streams, all conifer trees within 50 feet of the high water level of the stream and all hardwood trees within 30 feet of the high water level of the stream.(B)
For medium streams, all conifer trees within 30 feet of the high water level of the stream and all hardwood trees within 20 feet of the high water level of the stream.(C)
For small streams, all trees within 20 feet of the high water level of the stream.
Source:
Rule 629-642-0600 — Alternative Vegetation Retention Prescriptions, https://secure.sos.state.or.us/oard/view.action?ruleNumber=629-642-0600.