OAR 629-642-0400
General Vegetation Retention Prescription for Type D and Type N Streams
(1)
Intentionally left blank —Ed.(a)
Operators shall apply the vegetation retention requirements described in this rule to the riparian management areas of Type D and Type N streams.(b)
Segments of Type D or Type N streams that may be of a different size within an operation shall not be combined or averaged together when applying the vegetation retention requirements.(c)
Trees left to meet the vegetation retention requirements for one stream type shall not count toward the requirements of another stream type.(2)
Operators shall retain along all Type D, and large and medium Type N streams:(a)
All understory vegetation within 10 feet of the high water level;(b)
All trees within 20 feet of the high water level; and(c)
All trees leaning over the channel.(3)
Operators shall retain all downed wood and snags that are not safety or fire hazards within riparian management areas and streams. Snags felled for safety or fire hazard reasons shall be retained where they are felled unless used for stream improvement projects.(4)
Notwithstanding the requirements of section (2), vegetation, snags and trees within 20 feet of the high water level of the stream may be felled, moved or harvested as allowed in the rules for road construction, yarding corridors, temporary stream crossings, or for stream improvement.(5)
Operators shall retain at least 30 live conifer trees per 1000 feet along large Type D and Type N streams and 10 live conifer trees per 1000 feet along medium Type D and Type N streams. This includes any trees left to meet the requirements described in section (2) of this rule. Conifers must be at least 11 inches DBH for large streams and eight inches DBH for medium streams to count toward these requirements.(6)
Operators shall retain all understory vegetation and non-merchantable conifer trees (conifer trees less than six inches DBH) within 10 feet of the high water level on each side of small perennial Type N streams indicated in Table 7.(a)
The determination that a stream is perennial shall be made by the State Forester based on a reasonable expectation that the stream will have summer surface flow after July 15.(b)
The determination in subsection (6)(a) of this rule can be made based on a site inspection, data from other sources such as landowner information, or by applying judgment based upon stream flow patterns experienced in the general area.(c)
Operators are encouraged whenever possible to retain understory vegetation, non-merchantable trees, and leave trees required within harvest type 2 or harvest type 3 units (pursuant to ORS 527.676 (Leaving snags and downed logs in harvest type 2 or 3 units)) along all other small Type N streams within harvest units.(7)
Operators shall retain trees six inches or greater DBH to meet the following requirements (this includes trees left to meet the requirements of sections (2) and (5) of this rule):(a)
If the live conifer tree basal area in the riparian management area is greater than the standard target shown in Table 8 where the harvest will be a harvest type 2 or type 3 unit or in Table 9 where the harvest unit is a harvest type 1, partial harvest, or thinning, operators shall retain along all Type D, and medium and large Type N streams live conifer trees of sufficient basal area to meet the standard target.(b)
If the live conifer tree basal area in the riparian management area is less than the standard target (as shown in Table 8 where the harvest will be a harvest type 2 or type 3 unit or Table 9 where the harvest unit is a harvest type 1, partial harvest, or thinning), but greater than one-half the standard target shown in Table 8, operators shall retain along all Type D, and medium and large Type N streams all conifers 6 inches DBH or larger in the riparian management area (up to a maximum of 100 conifers per 1000 feet along large streams, and 70 conifers per 1000 feet along medium streams).(c)
If the live conifer tree basal area in the riparian management area is less than one-half the standard target shown in Table 8:(A)
Operators may apply an alternative vegetation retention prescription as described in OAR 629-642-0600 (Alternative Vegetation Retention Prescriptions), where applicable, or develop a site specific vegetation retention prescription as described in OAR 629-642-0700 (Site Specific Vegetation Retention Prescriptions for Streams and Riparian Management Areas); or(B)
Operators shall retain along all Type D, and medium and large Type N streams all conifers in the riparian management area and all hardwoods within 30 feet of the high water level for large streams and within 20 feet of the high water level for medium streams.(8)
In the Coast Range, South Coast, Interior, Western Cascade, and Siskiyou geographic regions, hardwood trees and snags six inches or greater DBH may count toward the basal area requirements in subsection (7)(a) of this rule as follows:(a)
All cottonwood and Oregon ash trees within riparian management areas that are beyond 20 feet of the high water level of large Type D and N streams, may count toward the basal area requirements.(b)
For large Type D and N streams, up to 10 percent of the basal area requirement may be comprised of sound conifer snags at least 30 feet tall and other large live hardwood trees, except red alder, growing in the riparian management area more than 20 feet from the high water level and at least 24 inches DBH.(c)
For medium Type D and N streams:(A)
Up to 30 square feet of basal area per 1000 feet of stream may be comprised of hardwood trees.(B)
Up to five percent of the basal area retained may be comprised of sound conifer snags that are at least 30 feet tall.(9)
In the Eastern Cascade and Blue Mountain geographic regions:(a)
The basal area of all retained live hardwood trees may count toward meeting the basal area requirements.(b)
For large Type D and N streams, up to 10 percent of the basal area requirement may be comprised of sound conifer snags at least 30 feet tall.(c)
For medium Type D and N streams, up to five percent of the basal area retained may be comprised of sound conifer snags that are at least 30 feet tall.(10)
Notwithstanding the requirements indicated in this rule, operators may conduct precommercial thinning and other release activities to maintain the growth and survival of conifer reforestation within riparian management areas. Such activities shall contribute to and be consistent with enhancing the stand’s ability to meet the desired future condition.(11)
When determining the basal area of trees along streams in a harvest unit, operators may use the average basal area for a tree’s diameter class, as shown in Table 4 in OAR 629-642-0100 (General Vegetation Retention Prescription for Type F Streams), or determine an actual basal area for each tree. The method for determining basal area must be consistent throughout the riparian management area.(12)
All live trees retained along Type D and N streams that otherwise meet the requirements for leave trees may count toward requirements for leave trees within harvest type 2 or harvest type 3 units (pursuant to ORS 527.676 (Leaving snags and downed logs in harvest type 2 or 3 units)).(13)
Trees on islands with ground higher than the high water level may be harvested as follows:(a)
If the harvest unit is solely on an island, operators shall apply all the vegetation retention requirements for a large Type F stream described in this rule to a riparian management area along the high water level of the channels forming the island.(b)
Otherwise, operators shall retain all trees on islands within 20 feet of the high water level of the channels forming the island and all trees leaning over the channels. In this case, conifer trees retained on islands may count toward the basal area requirement for adjacent riparian management areas so long as the trees are at least 11 inches DBH for large streams and 8 inches DBH for medium streams.(c)
All merchantable trees may be harvested from islands within small Type N streams.(14)
When applying the vegetation retention requirements described in this rule to the riparian management areas, if an operator cannot achieve the required retention without leaving live trees on the upland side of a road that may be within the riparian management area and those trees pose a safety hazard to the road and will provide limited functional benefit to the stream, the operator may submit a plan for an alternate practice to the State Forester to modify the retention requirements on a site specific basis.
Source:
Rule 629-642-0400 — General Vegetation Retention Prescription for Type D and Type N Streams, https://secure.sos.state.or.us/oard/view.action?ruleNumber=629-642-0400.