OAR 629-642-0105
General Vegetation Retention Prescriptions for Type SSBT Streams
(1)
The purpose for the vegetation retention prescriptions in this section is to ensure that, to the maximum extent practicable, forest operations will not impair the achievement and maintenance of the protecting cold water criterion described in OAR 340-041-0028 (Temperature)(11).(2)
The vegetation retention requirements for Type SSBT streams apply to harvest type 2 or harvest type 3 units in the following Geographic Regions as described in OAR 629-635-0220 (Geographic Regions): Coast Range, South Coast, Interior, Western Cascades, and Siskiyou. Use rules in OAR 629-642-0100 (General Vegetation Retention Prescription for Type F Streams) for Type 1 harvests along SSBT streams.(3)
Operators shall apply the vegetation retention requirements described in this rule to the riparian management area of the following streams:(a)
Type SSBT streams.(b)
The main stem of any Type F stream upstream of the mapped end of SSBT use to the higher of:(A)
The upstream boundary of the harvest unit containing SSBT, or(B)
The upstream boundary of any adjacent upstream harvest unit commenced within a year of completing harvest of the unit containing SSBT.(c)
For the purpose of this rule, “main stem” means the stream with the largest annual average flow at a confluence of two or more streams. The State Forester shall determine average annual flow by indexing average annual flow to the upstream drainage area and average annual precipitation as described in Forest Practices Technical Note 1 dated April 11, 1994. The State Forester may substitute field evaluations of average annual flow for the calculated flows described in the technical note.(4)
Segments of Type SSBT streams that are different sizes within an operation shall not be combined or averaged together when applying the vegetation retention requirements.(5)
Trees left to meet the vegetation retention requirements for one stream type shall not count towards the requirements of another stream type.(6)
Operators shall retain:(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.(7)
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.(8)
Notwithstanding the requirements of section (6) of this rule, vegetation, snags and trees within the riparian management area of the stream may be felled, moved or harvested as allowed in other rules for road construction, yarding corridors, temporary stream crossings, or for stream improvement while maintaining required basal area and live conifer tree count.(9)
When harvesting in the riparian management area of a Type SSBT stream, an operator shall apply one of the following prescriptions, except as noted for Type SSBT Prescription 3 in section (12).(a)
Operators may apply Type SSBT Prescription 1 on any Type SSBT riparian management area as described in section (10) of this rule.(b)
If the basal area of trees six inches or greater DBH within the riparian management area but more than 20 feet from the high water level of the Type SSBT stream exceeds the total basal area target shown in Table 5, the operator may apply Type SSBT Prescription 2, described in section (11) of this rule.(c)
If a Type SSBT stream segment at least 200 feet in length meets the standards in Type SSBT Prescription 3, the operator may apply that prescription on the north side of the stream segment, as described in section (12) of this rule.(d)
If live conifer basal area within the riparian management area of a Type SSBT stream is less than half the standard target for a small or medium Type F stream in Table 2, the operator may apply the appropriate Alternative Prescription described in OAR 629-642-0600 (Alternative Vegetation Retention Prescriptions).(e)
For the riparian management area of any Type SSBT stream, the operator may propose a site-specific prescription in a plan for an alternate practice. Plans for alternate practices are subject to the review and approval of the State Forester. Site-specific prescriptions are described in OAR 629-642-0700 (Site Specific Vegetation Retention Prescriptions for Streams and Riparian Management Areas).(10)
Type SSBT Prescription 1:(a)
Retain all trees within 60 feet of the high water level of a small stream.(b)
Retain all trees within 80 feet of the high water level of a medium stream.(c)
Where SSBT Prescription 1 is applied, operators may count as wildlife leave trees all trees that meet wildlife leave tree requirements:(A)
Within 20 feet of the high water level.(B)
In the remainder of the riparian management area, up to 50 percent of the basal area trees used to meet the basal area target in Table 5.(C)
Any trees within the area described in (B) in excess of the basal area target in Table 5.(11)
Type SSBT Prescription 2:(a)
Operators shall retain trees that are well-distributed by length and width of the riparian management area beyond 20 feet of the high water level of the stream, minimize the creation of large gaps, favor small openings in the canopy, and leave residual trees in a manner that promotes understory as well as diameter and crown growth. Operators shall satisfy these requirements by meeting the following minimum standards:(A)
For small Type SSBT streams, the riparian management area length will be measured in 500-foot segments. Within each 500-foot segment at least 25 percent of the required basal area target, rounded up to the nearest whole number, and 50 percent of the required live conifer trees, rounded up to the nearest whole tree, shall be located between:(i)
20 feet and 40 feet of the high water level, see Table 5; and(ii)
40 feet and 60 feet of the high water level, see Table 5.(B)
For medium Type SSBT streams, the riparian management area length will be measured in 500-foot segments. Within each 500-foot segment at least 25 percent of the required basal area target, rounded up to the nearest whole number, and 50 percent of the required live conifer trees, rounded up to the nearest whole tree, shall be located between:(i)
20 feet and 50 feet of the high water level, see Table 5; and(ii)
50 feet and 80 feet of the high water level, see Table 5.(b)
For stream segments that are less than 500 feet, the required basal area and live conifer trees are reduced proportionally.(c)
The operator shall provide a description in the written plan and map where the measurement for the 500-foot stream segments begin and end.(d)
Operators shall retain live conifer trees:(A)
For small Type SSBT streams, at least 8 live conifer trees per 500 feet along the stream, located between 20 feet and 60 feet from the high water level. Live conifer trees must be at least 8 inches DBH to count toward these requirements, see Table 5.(B)
For medium Type SSBT streams, at least 15 live conifer trees per 500 feet along the stream, located between 20 feet and 80 feet from the high water level. Live conifer trees must be at least 8 inches DBH to count toward these requirements, see Table 5.(e)
Operators shall retain hardwood and conifer trees and snags six inches or greater DBH to meet the following basal area requirements:(A)
For small Type SSBT streams, conifer and hardwood basal area target is shown in Table 5.(B)
For medium Type SSBT streams, conifer and hardwood basal area target is shown in Table 5.(C)
Up to 10 percent of the basal area requirements may be comprised of sound conifer snags at least 30 feet tall.(f)
Where Type SSBT Prescription 2 is applied, operators may count as wildlife leave trees all trees that meet wildlife leave tree requirements:(A)
Within 20 feet of the high water level.(B)
In the remainder of the riparian management area, up to 50 percent of the basal area trees retained to meet the basal area target in Table 5.(C)
Any trees within the area described in (B) in excess of the basal area target in Table 5.(12)
Type SSBT Prescription 3:(a)
This prescription applies to Type SSBT streams where the stream valley direction is between 60 and 120 degrees east and 240 and 300 degrees west on a compass bearing of 0 and 360 degrees as north. Operators shall:(A)
Retain all trees within 40 feet of the high water level on the north side of a Type SSBT stream where the stream valley direction criteria are met.(B)
The operator shall describe in a written plan and map where the alternative prescription is intended to be implemented.(b)
Where Type SSBT Prescription 3 is not applied, the operator shall apply either Type SSBT Prescription 1 or 2.(c)
The State Forester shall maintain a map showing stream valley direction for applying Type SSBT Prescription 3.(d)
The State Forester may substitute field evaluations of stream valley direction instead of the map.(A)
The field-based evaluation shall measure the stream valley direction with a minimum of 200-foot stream segments.(B)
The stream segment must meet the stream valley direction criteria listed above to apply SSBT Prescription 3.(e)
Where Type SSBT Prescription 3 is applied, operators may count all trees that meet the wildlife leave tree requirements retained within 40 feet of the high water level as wildlife leave trees.(13)
Notwithstanding the requirements indicated in this rule, operators may conduct pre-commercial 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.(14)
When determining the basal area of trees, the operator may use the average basal area for a tree’s diameter class, as shown in Table 4, or determine an actual basal area for each tree. The method for determining basal area must be consistent throughout the riparian management area.(15)
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 State Forester may approve a plan for an alternate practice to modify the retention requirements on a site specific basis.
Source:
Rule 629-642-0105 — General Vegetation Retention Prescriptions for Type SSBT Streams, https://secure.sos.state.or.us/oard/view.action?ruleNumber=629-642-0105.