FiveMileBell Planning Area Ownership

Transcription

1 Fivemile Bell Landscape Management Project Deadwood Assessment Part A: Snags and Coarse Woody Debris INTRODUCTION The Fivemile Bell project area is about 1 air miles southeast of Florence, Oregon. The public land survey description for the project area is Township 19 South, Range 11 West, sections 2 and 3: and Township 2 South, Range 11 West, sections 1-5, 8-12, and 21-23: Willamette Meridian: Douglas County, Oregon. The project area is about 5,792 acres in size and includes Fivemile and Bell Creeks in the Tahkenitch Creek watershed. Approximately 3,723 acres of the area is on National Forest System (NFS) land, of which 1,391 acres of NFS ownership are comprised of young forest plantations ranging from 15 to 6 years of age. About 1,756 acres of the project area are privately owned, 38 acres are managed by the Bureau of Land Management, and less than 5 acres are managed by Douglas County. Figure 1. FiveMileBell Planning Area Ownership ,723 1,756 BLM County Private Siuslaw Approximately 2,332 acres of the NFS land within the project area consists of natural stands greater than 8 years old and includes a minor amount in roads, streams and rivers, and meadows. Forested stands proposed for commercial thinning comprise about 484 acres of NFS land in the project area. Approximately 97 acres of the plantations on NFS lands within the planning area would be deferred (Figure 2). Page 1

2 Figure 2. Fivemile Bell Landscape Management EA Proposed Project for Upland Area ,332 Natural Stand Proposed Commercial Thin No Thinning MANAGEMENT DIRECTION Late-successional Reserve Assessment Guidance The Oregon Coast Province Southern Portion Late-Successional Reserve Assessment (LSRA) for this planning area (USDA Forest Service 1997), documents the stand structure and composition of mature natural stands (Table 1). In addition, Tables 11 and 12 (based on Spies et. al 1988) in the assessment discloses the range of snags or down wood volumes per acre found in natural stands of different age classes in the Oregon Coast Range and those results are summarized in Table 2. The objective of the late successional reserves is to protect and restore habitat related to late successional species. The assessment concluded that the loss of the large CWD component is long-term and there is very limited opportunity to create CWD >2" in diameter in the 25-5 year old plantations. The assessment recommended prescriptions that would set managed stands on a trajectory to meet the snag and downed wood levels found in mature and old-growth stands while still providing for an acceptable level of CWD in young stands. Northern Spotted Owl and Marble Murrelet Recovery Plan Guidance Deadwood in the form of snags and downed wood are important habitat components for a variety of species. The recovery plans for the northern spotted owl (USFWS 1992, USFWS 28) and the marbled murrelet (USFWS 1997) recommended changing the trajectory of managed stands from wood fiber production to a condition that more closely replicates natural stand conditions. Page 2

3 Table 1. From LSRA - Table 9. Structure and Composition of the Mature Condition of Late-Successional Stands by Sub-Series Environments. Information is expressed in number per acre Hemlock- Dry (12 plots) Hemlock- Moist (73 plots) Hemlock- Wet (95 plots) Species Small Med. Large Giant Total Small Med. Large Giant Total Small Med. Large Giant Total Bigleaf maple Red alder Sitka spruce Douglas-fir Western redcedar Western hemlock Total Live Trees (37) (38) (23) Hemlock -Dry (56 plots) Hemlock - Moist (59 plots) Hemlock - Wet (3plots) Snags Logs Spruce- Dry (13 plots) Spruce- Moist (45 plots) Spruce- Wet (32 plots) Red alder Sitka spruce Douglas-fir Western redcedar Western hemlock Total Live Trees (49) (44) (33) Spruce -Dry (4 plots) Spruce - Moist (5 plots) Spruce - Wet (7 plots) Snags Logs Live tree data from 1987 Vegetation Resource Survey 194 plots and 1984 Siuslaw Ecoplot Intensive Survey 184 plots. Snag and Log data from CVS and Ecology plots. Hard and soft snag and log condition were not separated out. This information was not included in the LSRA. Size classes: Small = inches dbh Medium = inches dbh Large = inches dbh Giant = 48.+ inches dbh (X) Total Medium, Large and Giant conifer trees Page 3

4 DESIRED CONDITION, BASED ON SUCCESSIONAL PATHWAYS Successional pathways are defined by the typical, dominant compositional and structural stages that can be expected as vegetative communities develop following disturbance. Conceptual models of succession were developed for each environment by using inventory information (Table 1) and field observation (LSRA, 1997). Research by Tappenier et al. (1997) has shown evidence that many of the Coast Range s oldgrowth forests appear to have developed from relatively widely spaced trees that were established in the wake of a series of infrequent disturbances. They quickly developed large, tapered stems, big crowns, and general vigor; all of which contributed to their longevity and stature in old-growth forests. In contrast, young stands today are developing from dense, singleaged, uniformly planted stands or naturally established conifers. Thinning is an opportunity to move plantations to densities closer to those developed naturally. Deadwood is only one element considered in restoration thinning. Other important components in restoration of late-successional habitat include development of individual tree structure to provide large diameter limbs and providing nesting habitat for northern spotted owls and marbled murrelets; and the opening of tree canopies to provide enough light to reach the forest floor which enhances understory development, diversity, and provides a multi-story canopy. Without thinning, understory tree development and large diameter limb development is substantially delayed. Large limb development may never occur within these overstocked stands. Page 4

5 MODELING DEADWOOD SIZE AND FREQUENCY IN UNTHINNED PLANTATIONS The size and number of snags created in unthinned plantations through time is an important component for assessing the effects of proposed thinning prescriptions the in Late Successional Reserves (USDA Forest Service 1994). Growth models calibrated for this region are being used to project live tree growth and mortality. Forest Vegetation Simulator- Pacific Northwest Variant ( us/fmsc/fvs/index.shtml) and ORGANON ( are two models commonly used to predict tree growth and suppression mortality as stands approach expected maximum tree densities. The Forest Vegetation Simulator (FVS_PN) provides the ability to modify most growth and mortality functions to conform to local observations of stand development. The intent of this analysis is to compare suppression mortality projections from available growth model using default growth model parameters to observed growth data from the Siuslaw National Forest. Following the comparison, the model most accurately representing the observed mortality data will project potential suppression mortality within an unthinned stand at age 11 years. The Siuslaw National Forest participates in the Siuslaw Thinning and Underplanting Density Study (STUDS) with the USFS Pacific Northwest Research Station and Oregon State University Forest Science Department (Chan et. al, 26, Poage and Anderson, 27). The purpose of STUDS is to determine responses to density treatment ranges considered for LSR development. This analysis uses the year 14 and 15 measurements of the unthinned treatments to validate growth model projections and infer which models may be the appropriate to project mortality into the future in dense, uniform stands. This analysis uses three no-thin, unplanted one-acre STUDS plots on three sites distributed across the Siuslaw National Forest to assess mortality development patterns. Diameter distributions of live trees and accumulated mortality by diameter at death at the end of the growth period (age 46 years) are displayed in Figures 3, 4, and 5. Mortality is almost exclusively occurring in the smaller diameter classes. Virtually all mortality is suppression mortality with the exception of a broken top occurring in a larger tree within the first 8 years of the study at the Wildcat site. Page 5

6 Figure 3. Page 6

7 Figure 4. Page 7

8 Figure 5. The Cataract site plot was used to compare actual observed data with growth model projections. The initial data set from this plot at age 31 was entered into three models: FVS_PN, ORGANON_SMC and ORGANON_NWO. The FVS_PN variant was developed in 1995 from Forest Service and Bureau of Land Management data sets. The model is intended to represent the Siuslaw and Olympic national forests and adjacent forest lands (Keyser, 28). The ORGAON_SMC version was developed and continues to be updated with plot information from the Stand Management Cooperative (SMC) data set. This data set is composed of uniform planted stands with intense density control. Data from older uniform naturally stocked stands were used to supplement the younger SMC data set (Clappell, 1991, Hann et. al, 26). The Northwest Oregon version of ORGANON (ORGANON_NWO) was developed from from permanent plots in the predominantly natural stands in the Oregon State University school forest. Projections using the initial Cataract plot data at age 31 were projected for 15 years to age 46 to coincide with the end data set. Figures 6, 7 and 8 display the projected 15-year live tree distribution and accumulated mortality for each model. The two ORGANON models concentrate suppression mortality within the smaller diameter classes, while the FVS_PN distributes suppression mortality proportionally across diameter classes. This relationship is inconsistent with the STUDS data and other related studies (Dodson, 212). The two ORGANON models simulate mortality distributed in the smaller size classes. This is more consistent with the observed STUDS data and other related studies than the FVS_PN simulation. The suppression Page 8

9 mortality distribution in FVS_PN is a recognized inaccuracy and is under consideration for recalibration (Smith-Mateja, 212). This analysis indicates that plantation stands would be expected to create suppression mortality similar to the range of projections found with the SMC and NWO_ORGANON models. Figure 6. Page 9

10 Figure 7. Page 1

11 Figure 8. The two ORGANON models were used to project the Cataract plot data through time to determine a possible range of snag size development to age 11 years. The results are displayed in Figures 9 and 1. The majority of mortality in these simulations occurred in the smaller diameter classes of less than 2 inches. It is unlikely that much suppression-created deadwood greater than 2 inches in diameter will develop in the unthinned plantation stands prior to age 11 years. Page 11

12 Figure 9. Page 12

13 Figure 1. EFFECTS OF THINNING ON DEADWOOD CREATION Silvicultural Prescriptions and Unit Size Plantations are reviewed by the interdisciplinary team. The original clearcut boundary is used as a starting point evaluating stands for restoration thinning. These boundaries are adjusted by stream buffers, hardwood dominated areas, acceptable stocking levels, unstable areas and logging feasibility resulting in generally a smaller area than the original clearcut boundary proposed for treatment. Thinning removes smaller diameter trees that potentially would experience suppression mortality. Snags and coarse woody debris are created following thinning. The no-cut buffers would still experience suppression mortality. Following thinning the stands retain more live trees than the target natural stand as derived from Table 1 (Structure and Composition of the Mature Condition of Late-Successional Stands by Sub-Series Environment found in the LSRA). Thinning from below is generally practiced. This removes the smaller diameter trees and leaves the larger dominant and co-dominant trees. Trees harvested range from 6 inches diameter and larger. About three to five years following thinning the stand is evaluated to determine if mechanical or if natural forces wind, insects or disease have created snags or coarse wood. At Page 13

14 that point it is determined how many snags and coarse wood pieces need to be created to meet the silvicultural prescription. Snags and coarse woody debris are created from the remnant trees generally 14 to 18 inches in diameter. Deadwood Development The snags and coarse woody debris less than 21 inches in diameter develop from the understory trees that regenerate following thinning as space and light are increased (Table 2). These snags may develop from the effects of suppression, insects, disease, or wind. The snags in the medium, large and giant would generally develop from trees that remain following thinning. These snags develop from the effects of insects, disease or wind with the effect of suppression mortality playing no or an insignificant role. Table 2. Summary of LSR Assessment Tables 11 and 12 Stand Age Tot al # of Sn ags/ Acr e> or = 2 dbh (all heights)* Young (<8 year s) 7 (4 t o 1) Mat ure 7 (8-199 years) (2 t o 12) Old Growth 7 (>199 years) (5 t o 9) *Includes all heights greater than 4.5 **Includes snags > or = 3.9 Spies and Franklin (1988) Tot al # of Tot al # of Sn ags/ Acr e> Sn ags/ Acr e or = 2 dbh < 2 dbh** AND > 16 (all heights) feet tall 2 41 ( t o 4) (24 t o 58) 3 47 (1 t o 5) (11 t o 83) 4 (2 t o 6) 9 (7 t o 11) Cu b ic Feet/ Acre of All Snags 1229 (697 t o 1761) 1486 (649 t o 2326) 2115 (1247 t o 2983) Down Wood Cu b ic Feet/ Acre 11 ( ) 1729 ( ) 3258 ( ) Thinning removes potential suppression mortality trees from stands. However, mortality from insects, disease and wind can and will continue following thinning. Early results from the Siuslaw Thinning and Understory Development Study (Yachats) indicate that mortality does occur, not just from suppression (Table 3). The Siuslaw Thinning and Under-planting for Diversity Study is designed to characterize the effects of thinning to increase structural heterogeneity on stand composition, structure vegetative diversity and productivity in young even-age managed stands. At one of the replication sites (Yachats) the number of snags >1 diameter at breast height (DBH) 16 years after the initial thinning and one year after a second thinning is disclosed in Table 3. The other sites have not been analyzed yet but appear to have similar number of snags per acre. Table 3. Snags/Acre in Yachats Site Treatment Snags/Acre >15" DBH Unthinned 7 1 TPA TPA TPA TPA = Trees Per Acre Page 14

15 Two studies from the Oregon Coast Range were designed to focus on snag and coarse woody debris development. Spies, (1988) showed that about 41 snags per acre less than 2 inches were in stands less than 8 years old. Carey, (27) showed that about 33 snags per acres less than 2 inches were in stands less than 8 years old. Carey broke the diameter classes a little further showing that about 26 of those 33 snags per acre were between 4 and 7 inches DBH leaving about 7 trees per acre in between 8 and 19 inches in diameter. Influence of Stand Density on Tree and Stand Characteristics Several studies have evaluated the effects of thinning on young Coast Range conifer stands. The effects of stand density and competition on individual trees and stands have been widely documented (Assmann 197; Curtis and Marshall 1986; Marshall et al. 1992; Smith et al. 1996). They include: Stem size - At low density, trees develop thick tapered stems. Crown characteristics - At low density, trees have large branches and wide, long crowns, and much of the stem is covered with foliage and branches. Tree vigor and stability - At low density, individual trees are vigorous and better able to resist windthrow, insects, and diseases, and they may produce more seed. Total stand growth and yield - Growth and yield are often low in very low-density stands. There is a tradeoff between tree size and the total volume of wood production. In addition, trees growing at low density develop large branches low on the stem, resulting in knots that might reduce wood quality. However, management objectives may include leaving some tress with large branches for wildlife habitat. Mortality from inter-tree competition - Mortality is less in low-density stands, and the trees that do die are generally considerably larger than dead trees in high-density stands. Understory vegetation. The less dense the stand, the more developed the understory vegetation. Regeneration of herbs, understory shrubs, hardwoods, and conifers is much higher under less dense stands because there are fewer overstory trees to compete for light and water. Regeneration of Understory Species Reducing overstory density and shrub cover frequently enables conifers, hardwoods, and shrubs to become established in the understory (Bailey and Tappenier 1998). In a comparison of paired thinned and unthinned stands on BLM land, seedling frequency ranged from.3 to 1. in thinned stands and. to.2 in unthinned stands. Douglas-fir occurred in 91 percent of the thinned stands but only 22 percent of the unthinned stands. Western hemlock and western redcedar, shade-tolerant species, were the most common conifers in the understory in all stands; their densities and frequencies were highest in thinned stands. Individual Stand Analysis For each stand in the proposed action, stand analysis of the original clearcut size, the proposed unit size, the residual stand trees per acre, the target structure and composition of mature condition of late-successional stands by Plant Association Group (PAG), and the number of created snags and downed wood prescribed following harvest was performed. It was found that stocking levels of live remnant trees per acre still exceeded the target for live and snag levels at the medium, large and giant size when the stand reached maturity. Size and levels of snags and coarse wood that are prescribed following thinning (created or natural) are within the tolerance Page 15

16 levels for this stand age. Additionally, the no-cut buffers provide the opportunity for the effects of suppression mortality to continue. Stand This stand was modeled showing growth and mortality with no thinning, thinning to 3 trees per acre (TPA) and thinning to 6 trees per acre at ages 55 and 125 years with thinning occurring at age 35. The model was run for mortality rate at ages 55 and 125 for the 3 and 6 trees per acre scenarios and the unthinned stand. Suppression mortality for the unthinned stand occurred, but even at 125 years of age no snags were greater than 19 inches DBH. Suppression mortality essentially is non-existent following thinning in the 3 and 6 trees per acre scenarios. Mortality at lower stand densities is a result of other causes such as disease, insects, or wind effects. Increase diameter growth through thinning provides the opportunity of this mortality in the 2 inch and greater diameter. The model was not run to include understory tree development which we assert is the place that smaller diameter snags and down wood will develop as the trees remaining following thinning will produce the snags in the large and giant size classes. CONCLUSION Review of the snag and coarse wood strategies outlined in the Late-Successional Reserve Assessment finds that the commercial thinning prescriptions generally fall between Strategy 2 Balance long-term and short-term needs by supplying a steady input of CWD over time and Strategy 3 Develop large trees for future CWD. Some snags and coarse wood are created following thinning (Strategy 2) and commercial thinning accelerates diameter growth compared to leaving a stand unthinned (Strategy 3). Strategy 4 - Allow natural successional processes to dominate by maintaining some untreated areas is prescribed within the no-cut buffers and also in the natural stands which was estimated to be 63 percent of the Fivemile Bell project area. Strategy 1 - Immediately improve nutrient cycling, fungal and soil invertebrate health, and habitat dependent species is prescribed within the pre-commercial thinning units within the watershed where the cut material is left on site. Page 16

17 Part B: Wildlife Tolerance Levels Analysis for Dead and Downed Wood Deadwood in the form of snags and down wood is important habitat components for a variety of species. The recovery plans for the northern spotted owl (USFWS 1992, USFWS 28) and the marbled murrelet (USFWS 1997) recommended changing the trajectory of managed stands from wood fiber production to a condition that more closely replicates natural stand conditions. The late-successional reserve assessment (LSRA) for this planning area (USDA Forest Service 1997), documents in Table 9 of the assessment, the stand structure and composition of mature natural stands. Tables 11 and 12 in the LSR assessment disclose the range of snags or down wood volumes per acre found in natural stands of different age classes in the Oregon Coast Range (Part A, Table 1). The objective of the late-successional reserves is to protect and restore habitat related to late-successional species. The assessment concluded the loss of the large CWD component is long-term and there is very limited opportunity to create CWD >2" in diameter in the 3-6 year old plantations. The assessment recommended prescriptions that would set managed stands on a trajectory to meet the snag and downed wood levels found in mature and old-growth stands while still providing for an acceptable level of CWD in young stands. Wildlife use and distribution of deadwood in Oregon coastal conifer and hardwood landscapes are documented by Mellen et. al (29) through the decayed wood advisor and management aid (DecAID). DecAID is an advisory tool to help managers evaluate effects of forest conditions and existing or proposed management activities on organisms that use snags and down wood. The guidelines associated with the use of DecAID indicate the fifth-field watershed is the appropriate scale to conduct the analysis of snags and downed wood. A full description on DecAID as well as a tutorial, cautions, glossary and references can be found at In addition, details on deadwood descriptions, assessment methods and current conditions on are found in Deadwood Analysis section of this report. National Forest System lands in the Coastal Lakes watershed, including the majority of the Project area, are all part of the Western Lowland Conifer-Hardwood NW Oregon Coast wildlife habitat type (WHT), (Mellen 29). Natural stands administered by the Siuslaw National Forest represent about 62% of the total lands administered in the Forest watersheds encompassed by the Project. Managed stands administered by the Siuslaw National Forest represent about 38% of the total lands administered by the Forest in the watersheds. In using DecAID for this analysis, the natural mature conifer stands are classified as being in the Large ( 2 dbh) structural class. In using DecAID for this analysis, the managed stands are classified as being in the Small/Medium ( 1-2< dbh) structural class. The following is a summary of the DecAID and current stand condition data information associated with the Western Lowland Conifer-Hardwood NW Oregon Coast wildlife habitat type, in the Small/medium Page 17

18 structural class (>1-2< dbh) and the Larger structural class ( 2 dbh). Landscape distribution conditions described for the watershed are limited to those acres administered by the Siuslaw National Forest and not the entire watershed. Snag Size Summarizing the available literature on species use of snags by diameter class, DecAID s cumulative species curves (Figures 1-5) identifies seven species (northern pygmy owl, Northern flying squirrel, brown creeper, red breasted nut hatch, long eared myotis, pileated woodpecker, and hairy woodpecker) that use snags smaller than 2 dbh for nesting, denning, resting, roosting or foraging, in both the small/medium as well as the larger tree structural classes. None of these species are closely associated with young stands containing snags 2 dbh. All either require or prefer large ( 2 ) snags in the managed stands or stands of mature to late-successional forest that are in close proximity to the young stands (Johnson, et.al, 21). Stands containing snags up to 2 could provide habitat for these seven species with a low level of assurance (3% tolerance level) of potential use. None of the other species plotted on the 3% curve would be provided for and no species plotted on the 5% (moderate level of assurance) and 8% (high level of assurance) curves would be provided for when a stand only contains snags 2 dbh. There are no species known to be associated only with snags < 2 dbh. Based on the deadwood assessment the natural stands in the Siltcoos River Frontal Pacific Ocean Watershed provide about 87% of the small size snags and about 89% of the large size snags in the watershed. The report documented unthinned 125 year-old managed stands would not develop trees 2 dbh; while trees in thinned stands would be 2 dbh, with over half reaching this size by age 8. By age 125 the majority of trees would be in the 2-3 size range, with some in the 3-38 size range. Page 18

19 Figures 1-5 are similar to the cumulative species curves in DecAID. Measurements are in inches and acres rather than centimeters and hect ares. Figure 1. Cumulative species curves for snag/tree dbh (in) used for nesting or denning in relation to snag size for 3%, 5% and 8% tolerance levels in the Westside Lowland Conifer-Hardwood Forest (Oregon Coast), Small/medium Trees Structural Condition Class. 14 Cumulative species or groups CNB NOFL PCE HAWO RBNU BRCR NFSQ NPOW RBSA CBCH PIWO SCNB NFSQ NPOW RBSA PCE CNB PIWO RBNU NOFL BRCR HAWO CBCH SCNB NOFL NFSQ HAWO NPOW PCE BRCR RBSA RBNU CNB PIWO SCNB CBCH 3% tolerance level 5% tolerance level 8% tolerance level Snag dbh (in) Figure 2. Cumulative species curves for snag/tree dbh (in) used for nesting or denning in relation to snag size for 3%, 5% and 8% tolerance levels in the Westside Lowland Conifer-Hardwood Forest (Oregon Coast), Larger Trees Structural Condition Class. 14 Cumulative species or groups NPOW CBCH RBSA PIWO SCNB CNB NOFL PCE NFSQ HAWO RBNU BRCR NPOW RBSA PCE CNB PIWO RBNU BRCR NOFL NFSQ HAWO CBCH SCNB NOFL HAWO NPOW PCE BRCR RBSA RBNU CNB NFSQ PIWO SCNB CBCH 3% tolerance level 5% tolerance level 8% tolerance level Snag dbh (in) Page 19

20 Figure 3. Cumulative species curves for snag/tree dbh (in) used for resting and roosting in relation to snag size for 3%, 5%, and 8% tolerance levels in the Westside Lowland Conifer-Hardwood Forest Wildlife Habitat Type (Oregon Coast), Small/Medium Tree and Larger Trees Structural Condition Classes. Cumulative species or groups % tolerance level 5% tolerance level 8% tolerance level LEMY LLMY LEMY BBBA LLMY PIWO BBBA LEMY LLMY PIWO PIWO BBBA Snag dbh (in) Figure 4. Cumulative species curves for snag/tree dbh (in) used for foraging in relation to snag size for 3%, 5%, and 8% tolerance levels in the Westside Lowland Conifer- Hardwood Forest Wildlife Habitat Type (Oregon Coast), Small/Medium Tree Structural Condition Class. 3 Cumulative species or groups 2 1 PIWO HAWO HAWO 3% tolerance level HAWO PIWO PIWO 5% tolerance level 8% tolerance level Snag dbh (in) Page 2

21 Figure 5. Cumulative species curves for snag/tree dbh (in) used for foraging in relation to snag size for 3%, 5%, and 8% tolerance levels in the Westside Lowland Conifer-Hardwood Forest Wildlife Habitat Type (Oregon Coast), Larger Tree Structural Condition Class. 4 Cumulative species or groups PIWO HAWO PIWO PIWO NOFL 3% tolerance level 5% tolerance level 8% tolerance level Snag dbh (in) Snag Density Based on the available information on species use of snags relative to snag density, DecAID s cumulative species curves documents four species use of snags 1 dbh for nesting, roosting or occurrence, and five species use of snags 2 dbh at the 3%, 5% and 8% tolerance levels (Figures 2 and 4). Figure 6. Cumulative species curves for density (#/ac) of snags 1 in dbh: species use of areas for nesting, roosting and occurrence with documented snag densities for 3%, 5%, and 8% tolerance levels in the Westside Lowland Conifer-Hardwood Forest Wildlife Habitat Type for the Small/medium and Larger Structural condition Classes. 5 Cumulative species or groups CNB BTWR NFSQ DOSQ NFSQ DOSQ BTWR CNB NFSQ DOSQ BTWR CNB 3% tolerance level 5% tolerance level 8% tolerance level Snag Density (#/ac); snags 1 in dbh Page 21

22 Figure 7. Cumulative species curves for density (#/ac) of snags 2 in dbh: species use of areas for nesting, roosting and occurrence with documented snag densities for 3%, 5%, and 8% tolerance levels in the Westside Lowland Conifer-Hardwood Forest Wildlife Habitat Type for the Small/medium and Larger Structural condition Class. 7 Cumulative species or groups LLMY LEMY BBBA CNB LEMY PIWO LLMY BBBA PIWO* CNB PIWO PIWO PIWO* PIWO* LLMY CNB * PIWO from foragingsites BBBA LEMY 3% tolerance level 5% tolerance level 8% tolerance level Snag Density (#/ac); 2 in dbh In the Small/medium structural class for snags 1 dbh (Figure 8), the percentage of the Siltcoos River Frontal Pacific Ocean Watershed watershed that has no measurable snag density is 25% or 4% more than reference conditions (21%). Similar differences are reflected in the 3 to 5% tolerance interval (DecAID Reference 2%- Current 29%). The percentage of the watershed that has zero to two snags per acre is 18% or 9% more than reference conditions (9%). The percentage of the landscape that provides for the 5-8% tolerance interval is less than reference conditions (DecAID Reference 3%-Current 2%). The percentage of the Siltcoos River Frontal Pacific Ocean Watershed watershed that provides for the species at the 8% tolerance level is less than reference (DecAID Reference 2%-Current 8%), reflecting a lack of large snags due to past timber harvest of mature stands. Integrating wildlife utilization data with the availability of snags relative to density in the Small/medium structural class, about 18% of the Siltcoos River Frontal Pacific Ocean watershed has snags ( 1 dbh) with a density that could provide for all four species at the 3% tolerance interval (Figures 2, 4). Three of the four species are provided for at the 5% tolerance interval on about 29% of the landscape. About 8% of the landscape could provide for the four species at the 8% tolerance intervals. Reminder: For comparison between the watershed and DecAID, managed stands in the Siltcoos River Frontal Pacific Ocean are classified as being in the Small/medium st ruct ur al class. Page 22

23 Figure 8. Distribution of snag density in the Westside Lowland Conifer-Hardwood Forest Wildlife Habitat Type; Small/medium Structural Condition Class for the Siltcoos River Frontal Pacific Ocean Watershed within tolerance intervals for snags 1 in. 6 Siuslaw NF Snag Density by Tolerance Level 5 DecAID Reference 49 Siltcoos River - Frontal Pacific 43 Percent of Area Alt 1 No Action Alt Snags/Acre -3% -2 Snags/Acre 3-5% Snags/Acre 5-8% Snags/Acre >8% >16.7 Snags/Acre Siltcoos Frontal Tolerance Interval; snagdensity 1 in dbh in Small Vegetation Condition In the Small/medium structural class for snags 2 dbh (Figure 9), the percentage of the Siltcoos River Frontal Pacific Ocean watershed that has no measurable snag density was 33% of the landscape and higher than the reference conditions (29%). The percentage of the watershed that has -1.1 snags per acre (-3% tolerance interval) is 27%; the DecAID Reference is 1%. The percentage of the landscape that currently provides for the 3-5% tolerance interval differs by 7% less from the reference conditions (DecAID Reference 2%-Current 13%). Current conditions in the 5-8% tolerance interval are 8% less than reference conditions (DecAID Reference 3%-Current 22%). The percentage of the Siltcoos River Frontal Pacific Ocean watershed that provides for the species at 8% tolerance intervals is less than the reference conditions (DecAID Reference 2%-Current 5%), reflecting a lack of large snags in managed stands. Page 23

24 Integrating wildlife utilization data with the availability of snags 2 dbh relative to density in the Small/medium structural class, about 27% of the Siltcoos River Frontal Pacific Ocean watershed has snags with a density that could provide for two of the five species at the 3% tolerance interval (Figures 3, 5). All five species are provided for at the 5% tolerance interval on about 13% of the Siltcoos River Frontal Pacific Ocean watershed. Less than 5% of the Siltcoos River Frontal Pacific Ocean watershed could provide for the five species at the 8% tolerance intervals. Page 24

25 Figure 9. Distribution of snag density in the Westside Lowland Conifer-Hardwood Forest Wildlife Habitat Type; Small/medium Structural Condition Class for the Siltcoos River-Frontal Pacific Ocean Watershed within tolerance intervals for snags 2 inches in managed stands. In the Large structural class (natural stands) for snags 1 dbh (Figure 1), the percentage of the Siltcoos River Frontal Pacific Ocean watershed that has no measurable snag density is 38% of the landscape and % more than reference conditions. The percentage of the Siltcoos River Frontal Pacific Ocean watershed that provides -8 snags per acre is similar to the reference conditions (DecAID Reference 3%- Current 29%). Currently there is a smaller percentage of the Siltcoos River Frontal Pacific Ocean watershed that provides snag densities at the 3 to 5% tolerance interval than found in the reference conditions (DecAID Reference 2%- Current 13%). The percentage of the watershed that provides for the 5-8% tolerance interval currently is also less than the reference conditions (DecAID Reference 3%- Current 16%). The percentage of the Siltcoos River Frontal Pacific Ocean watershed that provides for the species at the 8% tolerance level is lower than reference conditions (DecAID Reference 2%-Current 4%). Integrating wildlife utilization data with the availability of snags relative to density in the Large structural class, about 29% of the Siltcoos River Frontal Pacific Ocean watershed has snags ( 1 dbh) with a density that could provide for all four species at the 3% tolerance level and two of the four species at the 5% tolerance level (Figures 2, 6). All four species are provided for at the 5% tolerance level on about 13% and three of the four species at the 8% tolerance level on about 16% of the Siltcoos River Frontal Pacific Ocean watershed. About 4% of the Siltcoos River Frontal Pacific Ocean watershed could provide for all four species at the >8% tolerance level. Page 25

26 Figure1. Distribution of snag density in the Westside Lowland Conifer-Hardwood Forest Wildlife Habitat Type; Larger Structural Condition Class for the Siltcoos River-Frontal Pacific Ocean Watershed within tolerance intervals for snags 1 in DecAID Reference Siltcoos River-Frontal Pacific Ocean Percent of Area Snags/Acre -3% -8 Snags/Acre 3-5% Snags/Acre 5-8% Snags/Acre 4 >8% >29 Snags/Acre Tolerance Interval In the Large structural class, the percentage of the Siltcoos River Frontal Pacific Ocean watershed that has no measurable snag density for snags 2 dbh, is greater than the reference conditions (Figure 11, DecAID Reference 4%-Current 47%), as is the percentage of the watershed that provides less than 4 snags per acre (DecAID Reference 26%-Current 27%). The percentage of the watershed that provides for the 3-5% tolerance interval is 9% less than the reference conditions (DecAID Reference 2%-Current 11%). The percentage of the landscape that provides for the species at the 5-8% tolerance interval is also less than reference conditions (DecAID Reference 3%-Current 11%). The percentage of the watershed that provides for the 8% tolerance level is 16% less than the reference conditions (DecAID Reference 2%-Current 4%). Integrating wildlife utilization data with the availability of snags relative to density in the Large structural class, about 27% of the Siltcoos River Frontal Pacific Ocean watershed has snags ( 2 dbh) with a density that could provide for all five species at the 3% tolerance interval and three of the five species at the 5% tolerance interval (Figures 3, 7). All five species are provided for at the 5% tolerance interval and three of the five species at the 8% tolerance interval on about 11% of the Siltcoos River Frontal Pacific Ocean watershed. About 4% of the Siltcoos River Frontal Pacific Ocean watershed could provide for the five species at >8% tolerance intervals. Page 26

27 Figure 11. Distribution of snag density in the Westside Lowland Conifer-Hardwood Forest Wildlife Habitat Type; Larger Structural Condition Class for the Siltcoos River-Frontal Pacific Ocean Watershed within tolerance intervals for snags 2 in DecAID Reference Siltcoos River-Frontal Pacific Ocean Percent of Area Snags/Acre -3% -4 Snags/Acre 3-5% Snags/Acre 5-8% Snags/Acre >8% >11.9 Snags/Acre Tolerance Interval Assessment of Snags Alternative 1 No Action Considering the information discussed in the Deadwood Analysis (), except for snags considered danger trees along key forest roads, there would be no change in the current amount or recruitment rate (about 1 every 2 years at 2 trees per acre) of snags greater than 1 dbh in managed stands. Thus, the average number of snags per acre greater than 1 dbh would be about 7 per acre in 16 years, with no snags greater than 2 dbh expected. At the expected snag size in managed stands this would provide for 7 of the 12 species identified at the 3% tolerance level for snag size (Figures 7, 9, 1) in the short term or at age 125. None of the other species plotted on the 3% curve would be provided for and no species plotted on the 5% (moderate level of assurance) and 8% (high level of assurance) curves would be provided for when a stand only contains snags 2 dbh (Figures 7, 9, 1). There would be no change in the current amount or recruitment rate of snags, 1 dbh or 2 dbh in natural stands, except for snags considered danger trees along key forest roads. Based on the current natural stand condition data (Deadwood Analysis Section), the natural stands contain a range of snag sizes 2 dbh to provide for all the species at the 3%, 5% and 8% tolerance levels (Figures 7, 8, 1). Thus, natural stands would continue to be the primary source for small and large size snags in the watershed and provide for all the species evaluated across all tolerance intervals. Page 27

28 The managed stands evaluated for commercial thinning in Fivemile Bell planning area represent less than 1% of the small/medium structure class administered by the Siuslaw National Forest in the Siltcoos River Frontal Pacific Ocean. Adding, through mortality, seven snags per acre to the existing distribution of snag densities changes the distribution of snag density on the landscape across the tolerance levels. Thus, in the Small/medium structural class for snags 1 dbh (Figure 8), the percentage of the landscape that would have no measurable snag density in the Siltcoos River Frontal Pacific Ocean watershed would be 23% of the landscape, or 2% above the reference conditions. The percentage of the landscape in the -3% tolerance interval would remain greater than reference conditions (DecAID Reference 9%-No Action 2%). The percentage of the landscape in the 3-5% tolerance interval would be less than reference conditions (DecAID Reference 2%-No Action 32%). The percentage of the landscape that provides for the 5-8% tolerance interval would greater than reference conditions (DecAID Reference 3%-No Action 16%). The percentage of the landscape that provides for the species at the 8% tolerance level would remain less than reference conditions (DecAID Reference 2%-No Action 9%), and would continue to reflect a lack of large snags in managed stands. Considering that few, if any trees, 2 dbh were retained in regeneration units; that trees 2 dbh from the current cohort of trees would be the most dominant in the stand and therefore least likely to succumb from suppression mortality, the recruitment of snags 2 dbh is not likely to occur at a level that would change the current distribution of snags 2 dbh in the small/medium structural class until the structural class has grown to an average size that would classify it in the large structural class. Until a larger scale event such as a major wind storm, insect outbreak or large scale fire occurs; snag densities in natural stands across the Siltcoos River Frontal Pacific Ocean watershed are not expected to change from the existing conditions. Thus, the distributions of snag densities across the landscape by tolerance levels are not expected to change the Large structural class (Figures 1, 11). Proposed Alternative Considering the information discussed in the Deadwood Analysis (Appendix A), along with the above information and the current size of trees in managed stands, there would be no change in the number of snags in managed stands greater than 2 dbh in the short term (16 years). The majority of the residual trees are expected be 2 dbh by age 8. Thus, snags created in managed stands as part of this project would provide for 7 of the 15 species identified at the 3% tolerance level for snag size (Figures 5, 7, 8). The remaining 8 species would not be provided for at the 3% tolerance level and none of the species would be provided for at the 5% or 8% tolerance levels in managed stands. In the longer term (8-125 years), suppression mortality would not provide snags in thinned stands; however, non-suppression mortality (i.e. insects, disease, wind events snapping tree tops) would develop snags. Thus, thinned stands would develop snags of a size that provides for all the species evaluated at the 3% tolerance level and three of the species at the 5% tolerance level. Page 28

29 Since there is no planned change in the amount of natural stands, they would continue to be the primary source for small and large size snags in the watershed and provide for all the species evaluated across all tolerance intervals. Based on the design criteria to select trees in natural stands that are 3-5 dbh to mitigate for the loss of large snags in plantations, creating about 5 snags would provide for all species nesting, denning and foraging at the 3% and 5% tolerance levels (Figures 2, 5). This size range will provide snags for potential resting and roosting for all four species at the 3% tolerance level and three of four species at the 5% tolerance level (Figure 3). These sizes will provide potential nesting for 8 of 12 species at the 8% tolerance level; potential resting and roosting for 1 of 4 species at the 8% tolerance level; and potential foraging for the one species reported at the 8% tolerance level (Figures 2, 3, 5). The creation of about 4 snags per acre would add to the 7 snags expected to develop naturally in thinned stands over the next 16 years. This changes the distribution of snag density in the Siltcoos River Frontal Pacific Ocean watershed across the tolerance intervals. Thus, in the Small/medium structural class for snags 1 dbh (Figure 8), the percentage Siltcoos River Frontal Pacific Ocean watershed that would have no measurable snag density would be 13% of the watershed, or 8% below the reference conditions. The percentage of the landscape in the -3% tolerance interval would remain greater than reference conditions (DecAID Reference 9%-Proposed Alternative 14%). The percentage of the landscape in the 3-5% tolerance interval would be less than reference conditions (DecAID Reference 2%-Alt 2 12%). The percentage of the landscape that provides for the 5-8% tolerance interval would greater than reference conditions (DecAID Reference - 3%, Alternative 2-43%). The percentage of the landscape that provides for the species at the 8% tolerance level would be similar to reference conditions (DecAID Reference 2%-Alternative 2-17%). Like the No Action Alternative, the managed stands would continue to reflect a lack of large snags ( 2 dbh). At the 5 and 8% tolerance levels, Alternative 2 would be above the DecAID reference conditions. Though large snags would be created (about 5), the scale is too small to influence snag density in the Large structural class in the Siltcoos River Frontal Pacific Ocean watershed. Thus, measurable changes in the distributions of snag densities across the landscape by tolerance levels are not expected to change (Figures 1, 11) in Large structural classes until a larger scale event such as a major wind storm, insect outbreak or large scale fire occurs Down Wood Summarizing the available literature on species use of downed wood by size, DecAID s cumulative species curves (Figures 12-13) identifies 17 species that use downed wood 4 for foraging and occupancy at the 3%, 5% and 8% tolerance levels. The cumulative species curves for the Small/medium and Large structural condition class are the same. Table 1 displays the average or individual piece size required to provide for all 17 species at each tolerance level. Page 29

30 Figure 12. Cumulative species curves for down wood diameter (in) used at foraging sites and occupied sites in relation to average down wood size for 3%, 5%, 8% tolerance levels in the Westside Lowland Conifer-hardwood Forest Wildlife Habitat Type; Small/medium and Large tree Structural Condition Class. Cumulative species or groups % tolerance level 5% tolerance level 8% tolerance level DOSQ ERMI PWSH PGSA BTWR CLSA TOVO WSSK NFSQ WRSA SHMO NWSA VASH EMSA PJMO WWSK PJMO WRSA FDSQ SHMO ENSA NWSA VASH ERMI DOSQ PGSA BTWR PWSH TOVO CLSA ENSA VASH NWSA WSSK WRSA DOSQ PJMO TOVO CLSA PWSH NFSQ SHMO PGSA BTWR ERMI Average down wood diameter (in) Figure 13. Cumulative species curves for down wood diameter (in) used at foraging sites and occupied sites in relation to individual down wood size for 3%, 5%, 8%, tolerance levels in the Westside Lowland Conifer-hardwood Forest Wildlife Habitat Type; Small/medium and Large trees Structural Condition Class. 8 Cumulative species or groups % tolerance level 5% tolerance level 8% tolerance level HAWO PIWO PIWO CLSA WRSA ENSA ENSA WIWR CLSA WRSA ENSA HAWO WRSA PIWO CLSA WIWR HAWO WIWR Average down wood diameter (in) Page 3

31 Table 14. Down wood diameter required to provide for all species evaluated by tolerance level 3% Tolerance Level 5% Tolerance Level 8% Tolerance Level Average Size Single Piece Based on the available silvicultural information, the majority of the stands evaluated for commercial thinning have average tree sizes that potentially could meet the documented down wood sizes used by species at the 3 and 5% tolerance levels. The majority of these stands could potentially meet the sizes documented for 8 of the 15 species at the 8% tolerance level. The stands likely contain individual trees of a size that meet the needs for 4 of the 6 species at the 3% and 3 of the 6 at the 5%. None are likely to meet the documented sizes at the 8% tolerance level. Recruitment of downed wood through suppression mortality is most likely going to result in the smaller trees ( 1 ) in the stand, which would only provide for species at the 3% tolerance level. Recruitment of down wood through windthrow or disease (i.e. laminated root rot) may occur at any size class in the stand. The natural stands provide the full range of down wood sizes used by wildlife. Primary recruitment is the result either of snag decay, windthrow or disease (i.e. laminated root rot) causing root failure. Summarizing the available literature on species use of down wood by percent cover, DecAID s cumulative species curves (Figures 14 and 15) identifies 23 species that use down wood 4 for foraging and occupancy at the 3%, 5% and 8% tolerance levels. Page 31

32 Figure14. Cumulative species curves for percent cover of down wood ( 4 in diameter) in areas used for foraging or at occupied sites for 3%, 5%, and 8% tolerance levels in the Westside Lowland Conifer-hardwood forest wildlife Habitat Type and Small/Medium trees Structural Condition Class. Cumulative species 24 CLSA NFSQ NFSQ 22 ENSA WRSA WRSA PWSH PGSA PGSA 2 NFSQ TOCH TOCH WSSK PWSH PJMO 18 WRSA PJMO BTWR PJMO WSSK PWSH 16 NWSA BTWR WSSK TOCH ENSA SEMI 14 DOSQ ENSA * Class 4 and 5 CLSA SHMO CLSA down wood only ERMI 12 PGSA ** minimum size WRBV SHMO SHMO WRBV VASH measured = 7 in 1 TRSH PIWO** VASH WRBV vs 4 in for other PASH 8 PASH TRSH species FOSH PASH FOSH DEMO FOSH 6 DEMO VASH TRSH NWSA DOSQ DEMO 3% tolerance level 4 TOVO SPOW* DOSQ NSWA 5% tolerance level ERMI TOVO TOVO 2 PIWO** 8% tolerance level BTWR PIWO** SPOW* SPOW* Down wood percent cover Page 32

33 Figure 15. Cumulative species curve for percent cover of down wood ( 4 in diameter) in areas used for foraging or at occupied sites for 3%, 5%, and 8% tolerance levels in the Westside Lowland conifer-hardwood Forest Wildlife Habitat Type and Larger Trees Structural Condition Class. Cumulative species 24 WRBV*** WRBV*** WRSA 22 CLSA WRSA PGSA PWSH PGSA WRBV*** 2 NFSQ PWSH PJMO WSSK PJMO BTWR 18 WRSA WSSK PWSH PJMO BTWR WSSK 16 NWSA CLSA ERMI DOSQ ERMI NFSQ * Class 4 and 5 14 SHMO CLSA NFSQ wood only PGSA SHMO SHMO ** minimum size 12 PGSA ENSA VASH measured = 7 in WRBV WRBV ENSA 1 TRSH vs 4 in for other PIWO* VASH WRBV species PASH 8 PASH TRSH *** Class 3-5 FOSH PASH FOSH DEMO FOSH 6 DEMO VASH TRSH NWSA DOSQ DEMO 3% tolerance level 4 TOVO SPOW* ERMI PIWO** NSWA 5% tolerance level TOVO 2 8% tolerance level BTWR PIWO** SPOW* SPOW* Down wood percent cover In the Small/medium structural class for down wood 5 (Figure 16), the percentage of the Siltcoos River-Frontal Pacific Ocean watershed that has no measurable down wood is similar to reference conditions (DecAid Reference 5%- Siltcoos River-Frontal Pacific Ocean 5%). Current conditions reflect a greater percentage of the watershed in the -3% (DecAID Reference 25 Siltcoos River-Frontal Pacific Ocean 55%) and similar levels at the 3-5% tolerance intervals (DecAID Reference 2% - Siltcoos River-Frontal Pacific Ocean 21%) than the DecAID Reference. The percentage of the Siltcoos River- Frontal Pacific Ocean watershed that provided for species at the 5-8% tolerance level is less than the reference conditions (DecAID Reference 3% Siltcoos River-Frontal Pacific Ocean 15%). There is a similar difference at the 8% tolerance level (DecAID Reference 2%- Siltcoos River-Frontal Pacific Ocean 4%). The largest amount of down wood measured in the watershed is 15% ground cover. Page 33