Comparison of Current and Historic Stand Structure in Two IDFdm2 Sites in the Rocky Mountain Trench

by

R.W. Gray, E. Riccius and C. Wong

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Acknowledgements The authors would like to acknowledge the support and encouragement of several people who made this project feasible. First and foremost is Don Gayton, Extension Specialist with the Southern Interior Forest Extension and Research Partnership. Don’s perseverance in not only promoting fire as a legitimate process on the landscape but also garnering the funds to study it’s effects is monumentally appreciated. From the Cranbrook Forest District Denis Petryshen and Steve Byford. Thanks goes to Denis once again for the opportunity to give a presentation to the area Registered Professional Forester’s in November, and for all of his assistance in study site location, logistics, and permitting. The few, but highly stimulating, discussions with Steve on the topic of historical stand structure and disturbance regime has provided a useful perspective that has stayed with me throughout the coarse of the study. Steve was also instrumental in helping us choose a study site in Isidore Canyon. The field crew was rounded out by Matt McGee whose proficiency with a chainsaw, and increasing proficiency with an increment bore, was invaluable. Sectioning a large old tree with a chainsaw – and leaving it standing - in order to gain valuable historic data is much more difficult than it looks. Matt also mounted a great many of the cores and input all of the stand data into the database. Thanks also goes to Rob Lihou and Steve Grimaldi for the use of their wood shops in order to make core trays, sand and polish cores, and mount and sand the fire scar specimens. Thanks also goes to Dr. Ken Lertzman and the Simon Fraser University forest ecology lab for their support.

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Table of Contents 1.0 Introduction.......................................................................................................................... 1 2.0 Methods ............................................................................................................................... 2

2.1 Field Sampling Methodology ................................................................................. 4 2.2 Laboratory Analysis................................................................................................ 5 2.2.1 Fire History ...................................................................................................... 5 2.2.2 Stand Structure ................................................................................................. 6

3.0 Results

3.1 Master Chronology ................................................................................................. 6 3.2 Fire History ............................................................................................................. 6 3.3 Stand Structure........................................................................................................ 9

4.0 Conclusions

4.1 The Effects of Historic Fire Regime on Stand Structure ...................................... 21 4.2 Management Implications..................................................................................... 24

Appendix 1: Isidore Canyon Plot Tree Locations and Descriptions ........................................ 26 Works Cited.............................................................................................................................. 37

List of Tables Table 1. Study site and individual plot characteristics. .............................................................. 2 Table 2. Summary of fire dates for Lewis Ridge. ...................................................................... 7 Table 3. Summary of fire dates for Isidore Canyon ................................................................... 9 Table 4. Current and historic stand density for all trees >5 cm dbh for Lewis Ridge and Isidore Canyon..................................................................................................... 12 Table 5. Current and historic mean dbh for all trees >5 cm for Lewis Ridge and Isidore Canyon......................................................................................................................... 20 Table 6. Current and historic basal area for all trees >5 cm dbh on Lewis Ridge and Isidore Canyon ............................................................................................................ 21

List of Figures Figure 1. The Lewis Ridge study site. ........................................................................................ 3 Figure 2. The Isidore Canyon study site..................................................................................... 3

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Figure 3. Master chronology – Lewis Ridge. ............................................................................. 7 Figure 4. Fire history graph for Lewis Ridge ............................................................................. 8 Figure 5. Fire history graph for Isidore Canyon......................................................................... 8 Figure 6. Regeneration frequency, expressed as a proportion of trees in each age class over age Class............................................................................................................ 10 Figure 7. Regeneration frequency on the Isidore Canyon plot................................................. 11 Figure 8. Stand density increases for all species between 1850 and 1998 ............................... 12 Figure 9. Change in ponderosa pine stem density between 1998 and 1850 ............................. 13 Figure 10. Change in Douglas-fir stem density between 1998 and 1850................................. 13 Figure 11. 1998 and 1850 stem plots for Lewis plot 1 ............................................................. 14 Figure 12. 1998 and 1850 stem plots for Lewis plot 2 ............................................................. 15 Figure 13. 1998 and 1850 stem plots for Lewis plot 3 ............................................................. 16 Figure 14. 1998 and 1850 stem plots for Lewis plot 4 ............................................................. 17 Figure 15. 1998 and 1850 stem plots for Isidore Canyon ........................................................ 18 Figure 16. Diameter distribution in 1998 for the 4 Lewis Ridge plots..................................... 19 Figure 17. Diameter distribution in 1998 in the Isidore Canyon plot....................................... 20 Figure 18. Current density of juniper species on Lewis Ridge could be due to fire exclusion ............................................................................................................ 22 Figure 19. Grass cover in the Isidore Canyon plot is limited to small openings around pre-settlement era trees................................................................................ 23

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1.0 Introduction There is an ever-increasing recognition that contemporary stand characteristics in the dry forest types of western North America are highly different today than in the era that pre-dates European settlement1. Two ecosystems in particular, ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and interior Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), are thought to be well outside the historical range of variability for stand structure, species composition, and disturbance process. In the ponderosa pine types, which have been fairly extensively studied throughout their range, historic stand structure consisted of well-spaced, large-diameter trees, sparse pockets of younger trees, and highly diverse understories (Arnold 1950; Cooper 1960; Agee 1993; Arno et al. 1995; Gayton 1996; Sackett et al. 1996; USDA 1997). The pattern of stand ages was a mosaic of even-aged clumps of trees spaced over an uneven-aged landscape. Naturally occurring fires, on the order of every 2 to 15 years (Agee 1994; Gray and Riccius 1998; Riccius 1998), created bare mineral soil seedbeds and reduced grass competition enough to permit the regeneration of individual trees and clumps (Cooper 1960). These frequent fires were the dominant disturbance process that maintained historic stand structures (Biswell 1973; Weaver 1974; Harrington and Kelsey 1979; Habeck 1990; Arno et al. 1995). Contemporary stands of ponderosa pine consist of dense thickets of sapling and pole-sized trees, occasional large-diameter overstory trees, and poorly developed to depauperate understories. Insect- and disease-caused mortality is occurring at a higher rate today than in the past several centuries (Wickman and Swetnam 1996; USDA 1997), and in the past decade large areas of these ecosystems have been detrimentally affected by wildfire (Camp 1995; Camp et al. 1995; Camp and Everett 1996; Gaines et al. 1997; Sheppard and Farnsworth 1997). The changes in stand structure have been due to a combination of intensive livestock grazing, followed by reduced livestock grazing, favorable climate for seed production, and fire suppression (Barrett 1988; Covington and Moore 1994; Touchan et al. 1995). The heavy livestock grazing that began throughout the west in the mid- to late-19th century limited fire spread due to the loss of the fine grass fuels that historically allowed fires to spread over large areas (Gruell 1983; Arno and Gruell 1986; Clark and Starkey 1990; Skovlin and Thomas 1995; Barrett et al. 1997). Subsequently, the reduced competition from grass for moisture and light, and favorable germination and establishment conditions enabled many thousands of tree seedlings to develop into dense dog-hair thickets (Touchan et al. 1995). Less intensive research has been conducted to determine historic stand structures in dry, interior Douglas-fir-dominated forest types (Agee 1994). However, under a similar fire regime, Douglas-fir stand structure is considered to follow closely with that of ponderosa pine (Keane et al. 1990; Agee 1993). Historically, stands were open and comprised of large-diameter mature stems with little or no understory conifers (Vyse et al. 1990). Contemporary forest structure in the interior Douglas-fir type closely mimics that of the ponderosa pine type. Dense stands of sapling and pole-sized trees with depauperate understories are the norm (Bonnor 1990). Insect and disease problems, such as the western spruce budworm (Choristoneura occidentalis Freeman), Douglas-fir tussock moth (Orgyia pseudotsugata McDunnough), Douglas-fir beetle (Dendroctonus

1 The term “pre-European settlement” is used to describe the forest conditions prior to settlement by non-endemic people (Skovlin and Thomas 1995). The datum for pre-European settlement in the Rocky Mountain Trench will be 1850. As of that date no appreciable European settlement activities, outside of Catholic missionary work in 1846, had taken place in the Trench (Scott and Hanic 1979).

2

pseudotsugae Hopkins), and mistletoe (Arceuthobium spp.), are thought to be exasperated by contemporary stand structures (USDA 1997). Causal agents in getting these stands to their contemporary conditions also mimic those affecting ponderosa pine types, namely, early century selective harvesting, livestock grazing, and organized fire suppression (USDA 1997). The restoration and management of these ecosystems, consistent with conditions present during their evolutionary history, is now considered to be the most effective strategy for preserving diversity, maintaining endangered species, and avoiding the catastrophic disruption of ecosystem functions (Covington 1995). In order to begin the process of ecosystem restoration the reference conditions for these ecosystems need to be determined (Fule et al. 1997). Several approaches have been taken to determine reference conditions in similar ecosystems throughout the western United States (Arno et al. 1995; Camp 1995; Fule et al. 1997; Harrod et al. 1999). In each case the researchers were attempting to determine the historical range of variability (HRV) (Morgan et al. 1994) for both the ecosystem structure and composition and the dominant disturbance regime. Comparisons of historical stand structure and composition, and the disturbance regime that maintained it, can then be made with contemporary conditions. Uses of the data include estimates of departure of current vegetation conditions from those during the pre-settlement era, aids used to predict potential changes in forest composition and structure, and tools to develop objectives or targets for restoring forest composition, structure, and spatial pattern (Harrod et al. 1999). The draft Implementation Plan for the Kootenay/Boundary Land Use Plan (KBLUP) outlines the management guidelines for the restoration of these fire-maintained ecosystems. The 4 broad ecosystem categories outlined in the plan, shrublands, open range, open forest, and managed forest, are, at this time, lacking any substantive evidence concerning historic extent and composition. This study is intended to provide some quantitative assessment of what the HRV for conditions was so that objectives can be written for restoration activities. It must be remembered, however, that the study results can not be overly extrapolated as they only apply to a fairly small area of the Trench. 2.0 Methods This study was conducted in the Cranbrook Forest District of the Nelson Forest Region (Figure 1). Plots were established on two study sites, Lewis Ridge and Isidore Canyon (Figure 2). The Lewis Creek site is located at 50°45’30” latitude and 115°37’30” longitude while the Isidore Canyon site is located at 49°28’00” latitude and 115°44’00” longitude. Table 1. Study site and individual plot characteristics.

Study Site Elevation Aspect Slope BGC* Lewis Ridge

Plot 1 1030 m 180° 45% IDFdm2 02 Plot 2 1050 m 110° 50% IDFdm2 02 Plot 3 1100 m 140° 48% IDFdm2 02 Plot 4 1050 m 155° 54% IDFdm2 02

Isidore Canyon Plot 1 1158 m 57° 12% IDFdm2 01

* Biogeoclimatic zone classification system (Braumandl and Curran 1992).

3

Figure 1. The Lewis Ridge study site.

Figure 2. The Isidore Canyon study site. The four Lewis Ridge plots are situated over a range of elevations, aspects and slopes, but are all categorized as IDFdm2 02 sites (Table 1). All plots were located on moderately steep slopes (>45%) with Douglas-fir and ponderosa pine making up the overstory, and Rocky mountain (Juniperus scopulorum Sarge.) and common (J. communis) juniper and arrowleaf balsamroot (Balsamorhiza sagittata) and antelope bitterbrush (Purshia tridentata) in the understory. The

4

combination of xeric soil moisture and medium to poor soil nutrient characteristics signifies a designation of 02 as the site series. The Isidore Canyon plot is markedly different from the Lewis Ridge plots in both topographic characteristics and site series. The plot is located higher in elevation, on a northeast aspect versus the southeast to south aspects at Lewis, and on a very shallow slope gradient. One similarity shared by both sites is the general landscape location of a ridge line. Overstory species on the site include Douglas-fir, ponderosa pine, and western larch (Larix occidentalis Nutt.). The understory is comprised primarily of pinegrass (Calamagrostis rubescens) although scattered individuals of antelope bitterbrush and bluebunch wheatgrass (Agropyron spicatum) can be found in openings. The effects of topography and plant species composition are reflected in the IDFdm2 01 designation, which indicates a more mesic soil moisture regime as well as a more nutrient rich regime. Plots were randomly located on the Lewis Ridge site by creating a 100 m by 100 m grid over the entire study area and numbering the resulting squares. We identified potential study plots by picking random numbers and locating them on the grid. A set of criteria were established ahead of time as minimum acceptable conditions for plot placement. Because the objective behind the study was to established pre-settlement era stand structure the strictest criteria is the need for no historic timber harvesting evidence. Other criteria included no significant topographic or aspect changes. Due to the size of the plot, 50 m², or ¼ ha, and the long history of resource management activities in this portion of the Trench it was difficult finding intact areas to place the entire plot. The plot in the Isidore Canyon site was intentionally placed in it’s location because: 1) this area of Isidore Canyon is part of the Cranbrook Forest District’s Demonstration Forest; 2) the area is accessible by 4-wheel drive vehicle, making it useful as a demonstration site; and, 3) the high degree of disturbance in the area made locating a plot randomly extremely time consuming.

2.1. Field Sampling Methodology Field sampling methodology for determining the fire regime of the two sites follows Arno and Sneck (1977). The collection of fire-scar samples from a small area (<40 ha) in order to determine the historical fire regime (Martin and Sapsis 1991) in short-interval fire-return ecosystems is a widely accepted methodology (Madany et al. 1982; Covington and Moore 1994; Arno et al. 1995; Grissino-Mayer 1995; Agee 1996; Swetnam and Baisan 1996; Wright 1996; Arno et al. 1997; Gray and Riccius 1998). Fire-scarred trees were sampled throughout the study area on both Lewis Ridge and Isidore Canyon but not in any of the plots. We obtained 9 samples each from Lewis Ridge and Isidore Canyon. Where possible dead-downed material was used, however, the quality of this material is generally poor owing to advanced decay. Large-diameter live trees were sectioned, a large piece of wood or rock was placed in the wound, and flagging was placed on the tree to identify it as a potential threat. Small-diameter live trees were felled, sectioned to determine the best sample, and bucked up and scattered to reduce the wildfire build-up potential. Once the plots were randomly located 3 x 50 m plastic tapes were laid out to mark the sides and bottom boundaries of the plot. All plots were oriented perpendicular to the slope with side measurements corrected to horizontal distance. A 4th tape was used to mark off a 10 m strip

5

parallel to the bottom tape. Each tree >5 cm dbh and all snags and downed logs were recorded by coordinates between the 4 tapes. As each strip was completed the tape was moved an additional 10 m up slope to mark the next strip. All trees >20 cm dbh were cored at the base until the pith was extracted or until a near-complete core (in the case of heart-rot) was collected. Diameter at breast height, as well as height and species were also recorded for these trees. Trees in the 5-10 cm dbh, and 10-20 cm dbh size classes were dealt with differently because of their potentially high proportion as post-settlement era trees. Under this assumption every third tree in each size class was cored but every tree was located by coordinates, and dbh, height and species noted. In addition to the increment cores from the plots, we collected 10 increment cores from Douglas-fir, ponderosa pine and larch trees which are likely to express the climate signal for the region. Of these 10 cores, only 2 expressed a strong climate signal and were used in the master chronology. These 2 cores along with 8 increment cores exhibiting the climate signal from the plots were combined to create the master chronology, an essential tool for dendroecological work (Stokes and Smiley 1968; Fritts 1976; Fritts and Swetnam 1989). Using the common pattern of ‘marker’ years (either extremely narrow or wide rings) from the master chronology, we crossdated both the increment cores and fire scar samples to ensure accurate dates for tree ages and past fires (Madany et al. 1982; Dietrich and Swetnam 1984; Brown and Swetnam 1994; Grissino-Mayer 1995).

2.2. Laboratory Analysis The methods set out below have previously been reported in Gray and Riccius (1998).

2.2.1. Fire History The fire scarred samples were left to dry for approximately 3 weeks. Once dry, we cut the samples into manageable cross-sections (usually about 3 to 5 cm) with a band saw and mounted the sections exhibiting the greatest number of fire scars on 1/4 inch ranger board. We sanded each section with progressively finer sand paper, beginning with 50 grit and ending with 320 or 400. We were able to use all of the 9 samples from Lewis Ridge, but only 7 of the 9 samples from Isidore Canyon as two of the samples were too rotten to crossdate. For samples from live trees we crossdated the fire scars with the aid of a binocular dissecting microscope using methods outlined in Yamaguchi (1991) from the bark year to the pith. For samples obtained from dead material (logs and snags), we measured the ring widths using a Velmex - Acurite measuring stage and MEDIR software (Grissino-Mayer et al. 1996). The undated ring width series from the sample was compared with the ring width series of the master chronology using COFECHA (Grissino-Mayer et al. 1996) to determine the pith or inside date of the sample. We then visually crossdated the sample to confirm the inside date and to obtain the fire dates. Only distinct fire scars were dated leading to a potentially conservative population of fire dates for each site. We used the software package for fire history, FHX2, (Grissino-Mayer 1995) for graphical and statistical analyses of the fire history data. Statistics include a computation of mean, minimum and maximum fire intervals over a specified time period for each of the sites. This time period or

6

period of reliability (POR) ensures consistency in the fire history data. The POR is defined by the researcher (Grissino-Mayer 1995). For both sites, we defined the beginning and end of the POR by the earliest and latest fires when a minimum number of trees had the ability to record fire. For Lewis Ridge we used the criterion that at least 3 trees had the ability to record fire, while we only required 2 trees to have the ability to record fire at Isidore Canyon because there were fewer samples. This corresponds to a time period from 1694 to 1883 for Lewis Ridge and 1683 to 1894 for Isidore Canyon. For a more detailed discussion of the period of reliability see Grissino-Mayer (1995) and Riccius (1998).

2.2.2 Stand Structure The increment cores were left to dry and then mounted on wooden core mounts with wood glue. We sanded the cores with progressively finer sand paper beginning with 80 grit and ending with 320 or 400 grit. We crossdated the increment cores using methods outlined in Yamaguchi (1991) to ensure accuracy in the inside or pith date. In cases where the increment cores lacked a pith, we estimated the number of rings to the pith using sets of concentric circles with various widths which were copied onto transparencies. We chose the set of circles that most approximated the ring widths near the pith on the increment core and counted the number of circles to the estimated pith. While this method does provide an estimation of age at the pith, it is important to acknowledge the potential associated error. The error is related to our lack of knowledge of the actual ring widths (which can vary greatly) of the missing portion of the increment core. The final age of each increment core was entered into an Excel spreadsheet for graphical and statistical analyses. It should also be noted that even though trees were cored at the base and the pith may have been obtained, the true germination age of trees can still be off by as much as 20 years (Savage et al. 1996). 3.0 Results

3.1 Master Chronology The master chronology for Lewis Ridge spanned from 1700 to 1998. It contained a large number of marker years, either very narrow or very wide rings, as seen in Figure 3. The sensitivity of ring widths in the master chronology made crossdating relatively easy.

3.2 Fire History Lewis Ridge The fire history from our samples for Lewis Ridge spans a period of 430 years with the earliest recorded fire occurring in 1586 and the most recent recorded fire occurring in 1883 (Figure 4). This corresponds to 14 years with fires recorded on samples from this site. Thirty-two fire scars occurred on the 9 samples with an average number of about 4 scars per sample. Table 2 shows a summary of fire dates, the samples they occurred on and the number of recording trees for that year. A recording tree is simply a tree which has been previously scarred, since scarred trees are more susceptible to further scarring (Grissino-Mayer 1995, Fall 1998).

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Table 2. Summary of fire dates for Lewis Ridge.

Fire Date Samples Number of Recording Trees 1586 LR01 1 1619 LR01 1 1629 LR09 2 1694 LR02, LR05 4 1697 LR09 4 1708 LR05 4 1719 LR01, LR02, LR04, LR06, LR07,

LR08 8

1725 LR08 8 1751 LR02, LR04, LR06, LR07, LR09 8 1794 LR01, LR03, LR08 9 1815 LR05 9 1821 LR07 9 1831 LR01, LR03, LR04, LR09 9 1883 LR01, LR02, LR04, LR07 8

Using the POR from 1694 to 1883, we found a mean fire interval of 18.9 years. The minimum fire interval was 3 years and the maximum was 52 years. Of course, there has been a fire free interval of much longer, 115 years, from the last fire to the present. Isidore Canyon The fire history from the Isidore Canyon samples spans a period of 403 years with the earliest fire occurring in 1595 and the last fire occurring in 1894 (Figure 5). During this time period we identified 19 years with fire. A total of 38 fire scars occurred on the 7 samples which corresponds

Figure 3. Master Chronology - Lewis Ridge

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1700 1750 1800 1850 1900 1950

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Wide Rings

8

Figure 4. Fire history graph for Lewis Ridge.

Figure 5. Fire history graph for Isidore Canyon. to an average of about 5 scars per sample. Table 3 shows a summary of fire dates, the samples they occurred on and the number of recording trees for that year. For the POR from 1683 to 1894 the mean fire interval was 14.1 years. The minimum interval between fires was 1 year, while the maximum interval was 29 years. A fire was not recorded on any of our samples in the last 104 years.

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Table 3. Summary of fire dates for Isidore Canyon.

Fire Date Samples Number of Recording Trees

1595 IC07 1 1639 IC07 1 1664 IC07 1 1683 IC04, IC07 2 1705 IC04, IC06, IC07 3 1718 IC04, IC06 3 1729 IC04 3 1739 IC04, IC09 4 1751 IC01, IC04, IC06, IC07, IC09 5 1780 IC01, IC04 5 1802 IC01, IC04, IC06, IC07, IC09 5 1812 IC09 5 1826 IC03 6 1827 IC04, IC07 6 1849 IC09 6 1864 IC02, IC04, IC07 7 1873 IC03 6 1892 IC02 4 1894 IC01, IC03, IC09 4

3.3. Stand Structure Due to the high stand density in the lower diameter classes (5-10 cm and 10-20 cm) only a third of each of these trees was cored to determine an accurate age. Subsequent analysis has shown that a great deal of variability exists within the 5 plots when it comes to correlating diameter with age. To estimate the ages of trees < 20 cm dbh that we did not core, we examined the relationship between age and dbh for Douglas-fir and ponderosa pine in each plot. The data from each plot was fit with linear and loglinear least squares regressions (SPSS 8.0). Loglinear models were chosen over linear models if they produced more uniform distribution of residuals. The ages of trees that we did not core was estimated from their measured dbh and the respective equation. We analyzed the sensitivity of the estimated ages of trees < 20 cm dbh to the uncertainty in the parameters of the regressions; ages were re-estimated using the 95% upper and lower confidence limits of the regressions’ parameters and determined how this affects the percentage of trees estimated to be of pre-settlement establishment (>150 years old). Since we did not core every tree < 20 cm dbh, age should be estimated from regressions created from age - dbh relationships from trees < 20 cm dbh, not from the larger data set. Regressions using solely this data however, were very weak (r2 < 0.1). This suggests past radial growth of trees < 20 cm dbh in these plots was quite variable and thus any estimate of age incorporates a large amount of uncertainty. Indeed, using all data, dbh at best explains 62% of the variation in age in Douglas-fir (Lewis Plot 1). The strength of the relationship between age and dbh varies from plot to plot and species to species. In Isidore and Lewis Plot 1 estimates of Douglas-fir ages were not sensitive to uncertainty in our regressions. In both plots we can confidently say very few trees < 20 cm dbh are of pre-settlement origin. Uncertainty in our regressions has the greatest influence in Plots 2 and 3 where 25% and 8.5% of trees < 20 cm dbh were estimated to

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be > 150 years. However, because of the wide 95% confidence intervals around the parameters of these two regressions, it is possible for 6-67% and 0-100% of trees < 20 cm dbh (Plots 2 and 3 respectively) to be of pre-settlement origin. In Plot 4 all Douglas-fir < 20 cm dbh were estimated to be greater than 150 years. Very few ponderosa pine trees < 20 cm dbh were estimated to be of pre-settlement origin. Even with a conservative statistical analysis of the data the trend in stand structure change over time is readily apparent. Regeneration frequency, stand density, diameter distribution, mean dbh, and basal area/ha all show significant changes in the 148 year interval. Regeneration Frequency Regeneration frequency (Figure 6), is highly variable between the four Lewis Ridge plots and

Figure 6. Regeneration frequency, expressed as a proportion of trees in each age class over age class.

Lewis Plot 2

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then again between the Lewis Ridge study site and Isidore Canyon (Figure 7). Plot 1 indicates a pulse of regeneration occurring in the late 1800’s and early 1900’s with scattered, low frequency regeneration (survival) occurring as far back as the early 1600’s. Ponderosa pine begins to show up in the late 1800’s and continues to increase in frequency with Douglas-fir. Plot 2 is perhaps the most interesting in that it exhibits a very obvious bimodal regeneration pattern. The first occurs in the early 1700’s followed by a gradual slowing of regeneration, then an increase up to the late 1800’s when it abruptly slows. The pattern in plot 3 is similar to plot 1 except the pulse peaks earlier than in plot 1. Plot 3 also contains a fairly low but consistent rate of ponderosa pine regeneration which is dissimilar from all other plots. Plot 4 is different in that it indicates a single pulse in the early 1700’s. This pulse correlates well with the early pulse in plot 2 but unlike plot 2 a second, later pulse doesn’t materialize.

Figure 7. Regeneration frequency on the Isidore Canyon plot. The regeneration frequency exhibited on the Isidore Canyon site is similar to Lewis plot 1 except that the pulse builds up to the turn of the century then drastically ends whereas on the Lewis Ridge site it spills over into this century. The greatest similarity between all sites is the noticeable lack of significant regeneration since the 1920’s. For whatever reason none of the five plots contained large numbers of < 5 cm dbh trees which are cited as a common structural element in contemporary stands throughout the west (Bonnor 1990; Covington and Moore 1994; USDA 1997). Stand Density In all cases stand density has increased (Table 4); on some plots by as little as 7% (plot 4 on Lewis Ridge), and others by as much as 1640% (plot 1 on Lewis Ridge) (Figure 8). The average condition for the 5 plots is a 540% increase in stand density.

Isidore Canyon

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Table 4. Current and historic stand density for all trees >5 cm dbh for Lewis Ridge and Isidore Canyon. Plot No. 1998 Trees/ha

(all species) 1998 Trees/ha

(Fd) 1998 Trees/ha

(Py) 1850 Trees/ha (all species)

1850 Trees/ha (Fd)

1850 Trees/ha (Py)

Lewis 1 720 536 184 44 44 0 Lewis 2 516 500 16 308 292 16 Lewis 3 652 572 80 252 228 24 Lewis 4 492 472 20 460 440 20 Plot No. 1998 Trees/ha

(all species) 1998 Trees/ha

(Fd) 1998 Trees/ha

(Lw) 1850 Trees/ha (all species)

1850 Trees/ha (Fd)

1850 Trees/ha (Lw)

Isidore 1 1368 1360 8 180 180 0

Figure 8. Stand density increases for all species between 1850 and 1998. Ponderosa pine shows the higher level of variability in density over time. The species exhibits a dramatic increase in density in plots 1 and 3 on Lewis Ridge but no change over time on plots 2 and 4 (Figure 9). No ponderosa pine were recorded on the Isidore Canyon plot. Density of Douglas-fir shows a significant increase on all plots except Lewis plot 4 where the increase was only 32 trees/ha (Figure 10). Density increases per plot are shown in Figures 11 to 15. Diameter Distribution Diameter distribution comparisons also show a high degree of variability between and within plots (Table 5). Most of the plots in 1998 show a large proportion of trees in lower diameter classes with a gradual decrease in numbers of trees as diameter class increases (Figure 16 and 17). The only exception to the rule is Lewis Plot 4 which has a significant bulge in number of trees/ha in the intermediate diameter classes.

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Percentage Stand Density Increase in all Species

1640%

68%

259%

7%

760%

13

Figure 9. Change in ponderosa pine stem density between 1998 and 1850.

Figure 10. Change in Douglas-fir stem density between 1998 and 1850.

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Figure 16. Diameter distribution in 1998 on the Isidore Canyon plot. Reconstructing the 1850 mean DBH and basal area is difficult and the data is fairly rough. Several factors affect the accuracy of the data: 1) not all pre-settlement era trees were cored; 2) heart-rot prevents the accurate measure of the distance from the pith to the 1850 ring; 3) cores were collected at the base of the tree not at breast height; and, 4) cores have shrunk in length from the time they were extracted to the time they were analyzed. Accurate measures of contemporary mean DBH and basal area are presented with the estimates of conditions in 1850 (Table 5 and 6) to provide a relative comparison of change in stand structure between the two time periods. Table 5. Current and historic mean dbh for all trees >5 cm for Lewis Ridge and Isidore Canyon. Plot No. 1998 Mean dbh

(all species) (cm)

1998 Mean dbh (Fd) (cm)

1998 Mean dbh (Py) (cm)

1850 Mean dbh (all species)

(cm)

1850 Mean dbh (Fd) (cm)

1850 Mean dbh (Py) (cm)

Lewis 1 16.5 16.9 15.3 15.4 15.4 0 Lewis 2 21.5 21.4 23.8 17.0 17.2 7.5 Lewis 3 17.3 17.0 19.0 10.7 13.8 7.3 Lewis 4 25.5 25.5 24.5 16.8 16.8 0 Plot No. 1998 Mean dbh

(all species) (cm)

1998 Mean dbh (Fd) (cm)

1998 Mean dbh (Lw) (cm)

1850 Mean dbh (all species)

(cm)

1850 Mean dbh (Fd) (cm)

1850 Mean dbh (Lw) (cm)

Isidore 1 14.0 14.0 15.3 10.3 10.3 0 The accuracy of reconstructed basal area follows the same qualifications as those used in computing mean dbh. The data however, is useful in drawing relative comparisons between current basal area measurements and the variables used to compute them and historical conditions (Table 6). The contemporary basal area measurements, excluding Lewis plot 4, include a high proportion of small-diameter trees whereas, historically, on two of the plots, Lewis 1 and 4, the basal area was computed from a higher proportion of larger diameter trees.

0

1 00

200

300

400

500

600

700

5. 0-1 0. 0 1 0. 1 -1 5. 0

1 5. 1 -20. 0 20. 1 -25. 0 25. 1 -30. 0 30. 1 -35. 0 35. 1 -40. 0 40. 1 -45. 0 45. 1 -50. 0 50. 1 -55. 0 55. 1 -60. 0

D i a m e t e r ( c m )

Is id o r e P lo t 1

A ll

Fd

L w

21

Table 6. Current and historic basal area for all trees >5 cm dbh on Lewis Ridge and Isidore Canyon. Plot No. 1998 BA

(all species) (m²)

1998 BA (Fd) (m²)

1998 BA (Py) (m²)

1850 BA (all species)

(m²)

1850 BA (Fd) (m²)

1850 BA (Py) (m²)

Lewis 1 20.2 16.4 3.9 1.3 1.3 0 Lewis 2 24.8 23.8 1.0 8.2 8.0 0.2 Lewis 3 21.1 18.1 2.9 3.4 3.0 0.4 Lewis 4 29.0 27.6 1.4 10.4 10.4 0 Plot No. 1998 BA

(all species) (m²)

1998 BA (Fd) (m²)

1998 BA (Lw) (m²)

1850 BA (all species)

(m²)

1850 BA (Fd) (m²)

1850 BA (Lw) (m²)

Isidore 1 31.3 31.2 0.2 2.2 2.2 0 4.0 Conclusions

4.1. The Effects of the Historic Fire Regime on Stand Structure Stand structure has changed appreciably on several of the five sites studied between the baseline date of 1850 and 1998. Causal factors are likely numerous, however, the most critical factor, and the only one that can be reasonably measured, is fire. The frequency of fire activity on the two sites, 19 years at Lewis Ridge and 14 years in Isidore Canyon, lie well within the range of MFI for similar ecosystems in the western US and Canada (Arno 1976, 1980; Agee 1993, 1994; Arno et al. 1995; Gray and Riccius 1998). Site characteristics being what they are at Lewis Ridge, steep southeast to south aspects with an understory dominated by grasses, the MFI is likely to be fairly conservative. Not only were fire-scarred trees rare, but scarring episodes appear to be highly random. In one location two large >350 year old ponderosa pine stand no more than 20 m apart yet one is scarred and the other isn’t. With a historical stand structure consisting of well spaced trees and an understory of fine grass fuels and litter even head fires coming up the slope would result in little direct heat damage to trees boles. There are many subtle indicators of a historic high-frequency, low-intensity fire regime in Isidore Canyon that are not overly obvious in the current landscape. The presence of numerous fire-scarred trees, especially on the slope directly below the plot, and scattered plants such as antelope bitterbrush and bluebunch wheatgrass in small niches, indicate a historical stand structure that is highly different from the contemporary one. Fire scarred trees were not only more numerous in Isidore Canyon but also consisted mostly of western larch and ponderosa pine; neither of which occur significantly in the contemporary stand structure. The minimum and maximum fire intervals for both sites indicate a high level of historic species diversity but concerns over some current site occupants. Most identifiable understory species on Lewis Ridge exhibit a high level of adaptability to a short-interval fire regime. Arrowleaf balsamroot is reported to be either undamaged or slightly damaged by fire, but rarely killed. The species regenerates from a thick caudex located below the soil surface making it safe from all but the most intense fires (Holifield 1987). Antelope bitterbrush responds similarly but resprouts from the root-crown. In areas of high fuel build-up the plant can be killed (Bradley 1986), however historic fuel accumulations on Lewis Ridge were not likely to be very high. Both species could be in decline on the site do to overstory stem density and high crown closure.

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The two species of juniper growing on Lewis Ridge, the prostrate common juniper, and the more erect Rocky Mountain juniper, may be increasing in density on the site because of the interruption of the historic fire regime. Common juniper is considered to be susceptible to fire damage and slow to reestablish on a site postfire. The species can germinate from on-site soil-stored seed or carried on-site by birds or rodents, but germination periods are often long and germination rates are frequently poor (Tirmenstein 1988). Reasons for the high level of damage to individual plants include volatile foliage, high accumulations of litter around the plant, and its’ prostrate growth form. The historic fire regime on the site would not favor the establishment and expansion of common juniper. Rocky Mountain juniper does not resprout after fire like many other tree-form junipers in western North America. Young trees have compact crown shapes, highly volatile foliage, crowns close to the ground, and thin, flammable bark. Older trees, however, with thicker bark, can survive low-intensity surface fires (Tirmenstein 1986). The historic fire regime would likely prevent the establishment and expansion of this species as well. The interruption of the historic fire regime at the turn of the century has favored the ingrowth of both of these species (Figure 18) on Lewis Ridge as it has throughout large areas of the west (Gruell 1983; Skovlin and Thomas 1995). The current understory species composition in Isidore Canyon may not have changed much since the pre-settlement era, however, the proportions of individual species may have. Bluebunch

Figure 18. Current density of juniper species on Lewis Ridge could be due to fire exclusion. wheatgrass, which is currently found only in small openings, is considered to be well adapted to fire. The relatively few, coarse leaves, large stems, and a well-protected root crown limit the amount of heat damage the plant receives. Following fire the species regenerates vegetatively

23

(Bradley 1986). Both bluebunch wheatgrass and antelope bitterbrush, which occupy small canopy gaps, may have had a higher site occupancy in the pre-settlement era when stand density was significantly less and irradiance was significantly higher. The highest proportion of understory composition today is pinegrass, which is also highly adapted to fire (Snyder 1991). Determining the historical density of pinegrass in relation to bluebunch wheatgrass is difficult without specific data on local species dynamics. Even pinegrass however, is not in great abundance in parts of Isidore Canyon. The understory in much of the Canyon, especially in and around the plot, is either depauperate or moss covered (Figure 19). The effects of the interrupted fire regime on current overstory structure are highly variable over the five plots. Stand density has increased significantly on two plots since the last recorded fire with Lewis plot 1 and the Isidore Canyon plot showing a large bulge of regeneration occurring at the turn of the century. The Lewis Ridge plot 3 shows an older bulge centered around the 1860’s, plot 4’s bulge occurs in the early 1700’s, and plot 2 indicates a bimodal regeneration pattern with a bulge occurring in the early 1700’s and again in the 1860’s. The interruption of the fire regime in the late 1800’s may explain the pulse of regeneration on Lewis plot 1 and Isidore Canyon. The pulses observed in the period 1740 to 1770 and 1850 to 1890 may coincide with lengthy fire intervals and favorable germination conditions. Both time periods show up in the fire history record as long fire-free intervals on Lewis Ridge. The earlier of the two only yielded one fire over a 70 year period stretching from 1725 to 1795. The fire that did occur in 1751 however scarred >50% of the samples. Either the 1751 fire didn’t pass through plots 2 and 4 or the fire thinned the plots.

Figure 19. Grass cover in the Isidore Canyon plot is limited to small openings around pre-settlement era trees.

24

The later interval, 1850 to 1890, shows a similar pattern of a long fire-free interval from 1831 to 1883. This period comes to an abrupt end in 1883 with a fire that scars almost half of the samples. This fire is also the last recorded fire in the area. One conclusion that can be drawn from the data is the episodic nature of regeneration on the two study sites. Figures on regeneration pulses are fairly rare in the literature with most research focusing on the “epoch-making” ponderosa pine regeneration pulse in 1919 in the southwest (Arnold 1950; Savage et al. 1996; Mast et al. 1999). Regeneration associated with that particular event became established in a single year when an excellent seed year in 1918 was followed by high summer precipitation in 1919 (Savage et al. 1996). The other factor that may have contributed to the survival rate of this pulse was the interruption of fire. The pulses observed on Lewis Ridge in particular are episodic over decades not single years. Clues to understanding the processes involved in these regeneration episodes likely lie in the climate record. Dendrochronological studies in high elevation sites in the southern Canadian Rockies indicate general trends of narrow ring-widths in both the early 1700’s and mid 1800’s (Luckman 1997). Narrow ring-widths are correlated with periods of below-normal precipitation. The environment immediately following these drought-stress periods may be conducive to regeneration events. Additional studies to determine climate history are underway in parts of the Trench (E. Watson pers. comm.). This data will need to be augmented by additional stand reconstructions in order to correlate regeneration pulses with climate.

4.2. Management Implications The high degree of stand structure variability exhibited between the five plots makes it difficult to prescribe restoration treatments with specific density, species composition and inter-tree spacing targets. The study results have a limited geographical range and the data should not be overly extrapolated. Additional plots should be established in the Trench in order to gain a more comprehensive picture of the HRV for stand structure. For most plots the current stand structure is the product of random disturbance events spaced out over several centuries. On other plots the current stand structure developed within this century in the absence of disturbance. Despite these differences there are several general observations that can be made. With the exception of Lewis plot 4 all plots indicate the need to reduce stand density. On Lewis Ridge historic stand density appears to be related to aspect with the highest density occurring on the east aspect and the lowest on the south aspect. The single plot in Isidore Canyon, being situated on a northeast aspect, appears to contradict this; however, with only one plot in that study area few conclusions can be made regarding the HRV for local conditions. Species composition is variable with ponderosa pine occurring on the more southerly aspects as opposed to the more northeasterly aspects. Historic inter-tree spacing is highly variable with some clumps of trees and others being well-spaced. The historic fire regime is similar on both study sites. These general study findings indicate that restoration prescriptions using timber harvest can be written to include the following parameters: diameter limits, leave-tree species preferences, and minimum inter-tree spacing guidelines, and post-harvest residual stem density ranges by aspect. Silviculture prescriptions such as these are being written and implemented in similar dry forest types in B.C. and the western US. The use of prescribed fire in conjunction with timber

25

harvesting to meet restoration objectives should be investigated early in the planning phase and burn operation considerations incorporated in the harvest prescription (Harrington 1995; Arno and Harrington 1998). Difficulties arise from issues such as economies of scale, tree marking costs, product markets, and the limited number of experienced marking and harvesting crews (see Barbour and Skog 1997). Operational research should be conducted to determine the extent of these problems. Restoration efforts that rely solely on the use of prescribed fire are being researched in some jurisdictions (Peterson et al. 1994; Sackett et al. 1996), while in others it has become policy (BC Parks Conservation Policy). Using prescribed fire alone means collecting a great deal of information with which to formulate project objectives and provide inputs to operational burn plans. Even after all that it may come down to accepting the stochastic nature of fire effects. Project area conditions to be considered before embarking on this course include: fuel loading of large material, continuity of fine, surface fuels, ladder fuels, duff and litter accumulations at the base of old trees to be preserved, and, the target size class of the trees to be removed. These are all structural elements of the contemporary NDT-4 landscape that were regulated historically by fire.

26

Appendix 1: Isidore Canyon Plot Tree Locations and Descriptions

Tree Tag Number

Species Diameter (cm)

Height (m)

Final Date (from increment core)

Estimated Date (from age-diameter regression)

All Ages All Dates

001 Fd 14.2 11.5 118 118 1880 002 Fd 6.5 6.9 96 96 1902 003 Fd 7.9 6.8 100 100 1898 004 Fd 10.5 12.3 107 107 1891 005 Fd 11.3 12.3 1903 95 1903 006 Fd 7.1 6.0 1901 97 1901 007 Fd 8.8 10.0 102 102 1896 008 Fd 7.3 6.5 98 98 1900 Log Fd 7.0 97 97 1901

Snag Fd 6.2 95 95 1903 Snag Fd 10.6 108 108 1890 Snag Fd 9.0 103 103 1895 009 Fd 9.5 11.0 1902 96 1902 010 Fd 12.6 11.3 113 113 1885

Stem Location Map(Isadore Canyon)

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0

Meters

Met

ers

FdLwFd logFd snagLw logLw snag

Tree number 342

Tree number 001

27

011 Fd 13.9 11.5 117 117 1881 012 Fd 6.5 9.0 96 96 1902 013 Fd 8.6 10.1 102 102 1896 014 Fd 10.2 12.0 1907 91 1907 015 Fd 9.5 9.2 1900 98 1900 016 Fd 18.8 13.8 131 131 1867 017 Fd 16.5 13.8 125 125 1873

Snag Fd 7.2 98 98 1900 Snag Fd 8.0 100 100 1898 Log Fd 5.8 94 94 1904 Log Fd 6.0 94 94 1904

Snag Fd 11.0 109 109 1889 018 Fd 5.8 5.5 94 94 1904

Snag Fd 7.4 98 98 1900 019 Fd 17.6 13.2 1895 103 1895 020 Fd 8.8 11.0 1917 81 1917 021 Fd 6.6 7.0 1924 74 1924 022 Fd 8.9 11.0 103 103 1895 023 Fd 9.4 11.5 104 104 1894 024 Fd 9.6 11.6 1899 99 1899 025 Fd 12.5 12.0 113 113 1885 026 Fd 11.1 10.0 109 109 1889 027 Fd 10.1 9.8 1901 97 1901 028 Fd 20.4 14.0 1900 98 1900

Snag Fd 6.0 94 94 1904 Log Fd 6.0 94 94 1904 029 Fd 10.8 12.5 108 108 1890 Log Fd 6.5 96 96 1902 030 Fd 16.6 13.0 125 125 1873 031 Fd 21.4 13.0 1891 107 1891

Snag Fd 7.1 97 97 1901 032 Fd 11.5 12.7 1904 94 1904 033 Fd 11.7 11.5 111 111 1887 034 Fd 12.6 11.5 113 113 1885 Log Fd 10.0 106 106 1892 035 Fd 7.7 7.5 99 99 1899 036 Fd 17.4 13.2 1898 100 1898 037 Fd 10.2 10.5 106 106 1892 038 Fd 24.0 14.3 1865 133 1865 Log Fd 13.0 115 115 1883 039 Fd 6.3 6.5 95 95 1903 040 Fd 10.6 4.5 108 108 1890 041 Fd 6.9 5.0 1900 98 1900 Log Fd 9.0 103 103 1895 Log Fd 5.0 91 91 1907 Log Fd 25.0 149 149 1849 042 Fd 19.5 12.7 1906 92 1906

28

043 Fd 52.8 19.5 1693 305 1693 044 Fd 7.5 7.0 99 99 1899

Snag Fd 6.5 96 96 1902 045 Fd 13.8 12.5 117 117 1881 046 Fd 16.2 13.5 124 124 1874 047 Fd 8.2 11.5 101 101 1897 048 Fd 6.0 5.5 1915 83 1915 049 Fd 13.1 12.0 1895 103 1895

Snag Fd 6.1 95 95 1903 050 Fd 10.5 11.5 107 107 1891 051 Fd 7.7 6.5 99 99 1899 052 Fd 11.4 12.5 110 110 1888 053 Fd 7.2 10.5 98 98 1900 054 Fd 43.3 20.5 1728 270 1728 055 Fd 9.3 11.0 1895 103 1895 056 Fd 11.0 12.7 1904 94 1904 057 Fd 16.8 13.5 126 126 1872 058 Fd 12.8 13.0 114 114 1884

Snag Fd 27.3 156 156 1842 059 Fd 8.7 9.5 102 102 1896

Snag Fd 11.9 111 111 1887 Log Fd 6.5 96 96 1902 Log Fd 6.0 94 94 1904 060 Fd 7.7 9.0 99 99 1899 061 Fd 8.0 9.0 1904 94 1904 062 Fd 17.0 13.3 1902 96 1902 063 Fd 12.4 12.4 113 113 1885 Log Fd 36.0 181 181 1817 064 Fd 8.6 7.5 102 102 1896 065 Fd 15.1 12.4 121 121 1877 066 Fd 10.9 11.4 1906 92 1906 067 Fd 8.7 9.5 102 102 1896

Snag Fd 5.2 92 92 1906 068 Fd 19.5 13.0 133 133 1865 069 Fd 14.6 12.2 119 119 1879 070 Fd 11.2 11.8 1911 87 1911 071 Fd 7.4 10.1 1907 91 1907

Snag Fd 5.2 92 92 1906 Snag Fd 9.2 103 103 1895 072 Fd 12.9 12.5 114 114 1884 073 Fd 13.8 12.5 117 117 1881

Snag Fd 6.4 95 95 1903 Snag Fd 5.2 92 92 1906 Snag Fd 5.8 94 94 1904 Log Fd 5.0 91 91 1907 Log Fd 5.0 91 91 1907 Log Fd 5.0 91 91 1907

29

075 Lw 15.9 074 Fd 7.2 7.0 98 98 1900 076 Fd 8.3 9.5 101 101 1897 077 Fd 7.4 9.4 98 98 1900 078 Fd 9.5 10.0 104 104 1894 079 Fd 16.3 13.1 124 124 1874 080 Fd 6.6 4.5 96 96 1902

Snag Fd 5.0 91 91 1907 081 Fd 13.0 11.0 115 115 1883 082 Fd 8.6 6.5 1899 99 1899 Log Fd 5.0 91 91 1907 083 Fd 6.0 5.0 94 94 1904 084 Fd 5.2 4.5 91 1907 085 Fd 10.5 7.2 1904 94 1904 086 Fd 45.1 21.5 1758 240 1758 087 Fd 50.8 23.8 1877 121 1877

Snag Fd 52.8 230 230 1768 Log Fd 8.0 100 100 1898 088 Fd 6.8 7.8 1877 121 1877 089 Fd 14.1 11.1 118 118 1880 090 Fd 24.7 15.8 1812 186 1812 Log Fd 7.7 99 99 1899 091 Fd 14.1 9.9 118 118 1880 092 Fd 6.4 6.5 95 95 1903 Log Fd 7.5 99 99 1899 093 Fd 7.9 8.3 100 100 1898

Snag Fd 15.4 121 121 1877 094 Fd 22.0 17.6 1843 155 1843 095 Fd 12.2 11.5 1835 163 1835 096 Fd 18.6 13.1 131 131 1867 Log Fd 5.0 91 91 1907 Log Fd 5.3 92 92 1906 097 Fd 9.1 11.0 1836 162 1836 098 Fd 22.5 13.0 1834 164 1834

Snag Fd 8.3 101 101 1897 099 Fd 6.0 6.5 94 94 1904 Log Fd 7.1 97 97 1901 100 Fd 11.9 12.0 111 111 1887

Snag Fd 9.8 105 105 1893 101 Fd 20.1 13.8 1838 160 1838 102 Fd 6.5 6.2 96 96 1902 103 Fd 8.3 8.9 1900 98 1900

Snag Fd 8.5 101 101 1897 104 Fd 20.6 14.0 1847 151 1847 105 Fd 5.3 4.5 94 1904 106 Fd 51.2 19.3 1704 294 1704 107 Fd 8.2 7.0 101 101 1897

30

108 Fd 8.5 6.8 1898 100 1898 109 Fd 9.6 9.5 105 105 1893 110 Fd 10.2 10.5 1906 92 1906 111 Fd 6.8 6.5 97 97 1901 112 Fd 5.9 6.8 1921 77 1921 113 Fd 12.3 13.0 112 112 1886 114 Fd 12.3 13.3 112 112 1886 115 Fd 10.7 12.7 1908 90 1908 116 Fd 7.0 8.0 97 97 1901 117 Fd 10.9 12.0 1764 234 1764 Log Fd 50.0 222 222 1776 118 Fd 7.4 11.5 98 98 1900 119 Fd 11.4 10.5 110 110 1888 120 Fd 6.1 9.5 1888 110 1888 121 Fd 14.3 13.5 1902 96 1902

Snag Fd 5.7 93 93 1905 122 Fd 6.8 8.1 97 97 1901 123 Fd 9.3 11.5 104 104 1894 124 Fd 11.7 13.0 111 111 1887 125 Fd 12.0 12.3 112 112 1886 126 Fd 17.0 14.0 1899 99 1899 127 Fd 9.1 9.0 1902 96 1902 128 Fd 8.2 8.7 101 101 1897 129 Fd 9.2 10.2 103 103 1895 Log Fd 9.8 105 105 1893 130 Fd 10.9 11.5 108 108 1890 131 Fd 9.4 9.0 1898 100 1898 132 Fd 14.0 13.5 117 117 1881 133 Fd 18.5 14.5 1898 100 1898 134 Fd 5.8 9.0 94 94 1904 135 Lw 14.7 15.0

Snag Fd 6.0 94 94 1904 136 Fd 11.0 12.0 109 109 1889 137 Fd 11.4 12.5 1898 100 1898 138 Fd 8.9 10.7 103 103 1895 139 Fd 12.3 12.5 112 112 1886

Snag Fd 7.8 99 99 1899 Snag Fd 5.2 92 92 1906 Snag Fd 13.8 117 117 1881 140 Fd 14.7 12.8 119 119 1879 141 Fd 16.5 12.7 1903 95 1903 Log Fd 8.5 101 101 1897 142 Fd 7.5 7.0 1898 100 1898 143 Fd 11.5 12.1 110 110 1888 144 Fd 5.6 9.5 93 93 1905 145 Fd 9.9 9.3 106 106 1892 146 Fd 8.2 8.9 1902 96 1902

31

147 Fd 6.6 7.2 96 96 1902 148 Fd 34.0 18.8 1893 105 1893 149 Fd 7.0 7.5 97 97 1901 150 Fd 6.8 11.0 1900 98 1900 151 Fd 7.7 10.1 99 99 1899

Snag Fd 8.4 101 101 1897 152 Fd 6.9 7.4 97 97 1901 153 Fd 36.6 17.8 1874 124 1874 154 Fd 10.8 11.2 108 108 1890

Snag Fd 25.9 152 152 1846 155 Fd 46.8 20.2 1764 234 1764 Log Fd 22.0 141 141 1857 156 Fd 33.9 18.7 1761 237 1761 157 Fd 25.6 18.8 1756 242 1756 158 Fd 29.6 18.7 1757 241 1757 159 Fd 28.1 18.8 1762 236 1762 160 Fd 16.7 15.0 1839 159 1839 161 Fd 43.3 19.2 202 202 1796 162 Fd 15.8 15.3 123 123 1875 163 Fd 11.2 11.6 109 109 1889 164 Fd 28.0 14.1 1806 192 1806 165 Fd 14.8 14.0 1852 146 1852 166 Fd 5.8 6.4 1865 133 1865 Log Fd 23.2 144 144 1854 167 Fd 9.7 12.5 105 105 1893 168 Fd 8.7 6.0 102 102 1896 169 Fd 24.0 18.0 1854 144 1854

Snag Fd 6.6 96 96 1902 Snag Fd 7.3 98 98 1900 170 Fd 8.0 10.1 1864 134 1864 171 Fd 6.0 6.5 94 94 1904 Log Fd 11.0 109 109 1889 172 Fd 14.1 13.5 118 118 1880 173 Fd 8.6 10.5 102 102 1896

Snag Fd 5.2 92 92 1906 Snag Fd 13.3 115 115 1883 174 Fd 19.9 15.2 135 135 1863 175 Fd 5.8 7.3 1875 123 1875 176 Fd 13.6 13.6 1850 148 1850 Log Fd 6.5 96 96 1902 177 Fd 22.6 17.0 1848 150 1848 178 Fd 9.5 10.3 104 104 1894 179 Fd 14.5 13.7 119 119 1879 180 Fd 22.6 14.5 1851 147 1851 Log Fd 6.0 94 94 1904 Log Fd 5.0 91 91 1907 181 Fd 9.2 11.8 103 103 1895

32

182 Fd 13.0 12.7 115 115 1883 183 Fd 11.4 13.0 1856 142 1856 184 Fd 10.2 10.3 106 106 1892 185 Fd 10.5 12.5 107 107 1891

Snag Fd 9.2 103 103 1895 Log Fd 10.0 106 106 1892

Snag Fd 10.3 107 107 1891 Snag Fd 13.8 117 117 1881 186 Fd 26.2 14.1 1829 169 1829

Snag Fd 9.8 105 105 1893 187 Fd 10.5 9.6 1842 156 1842

Snag Fd 8.9 103 103 1895 188 Fd 8.2 7.2 101 101 1897 189 Fd 17.5 13.5 128 128 1870 190 Fd 19.8 15.0 1860 138 1860 191 Fd 7.2 9.5 98 98 1900

Snag Fd 8.5 101 101 1897 192 Fd 26.2 17.5 1865 133 1865 193 Fd 24.4 17.0 1862 136 1862 194 Fd 10.6 9.2 1851 147 1851 195 Fd 21.2 15.4 1842 156 1842 196 Fd 7.2 4.5 98 98 1900 197 Fd 6.2 7.0 95 95 1903 198 Fd 9.6 7.5 1918 80 1918 199 Fd 14.5 11.7 119 119 1879 200 Fd 6.4 4.2 95 95 1903

Snag Fd 7.5 99 99 1899 201 Fd 7.7 7.5 99 99 1899 202 Fd 6.5 6.0 1895 103 1895 203 Fd 6.4 5.5 95 95 1903 204 Fd 10.0 9.2 106 106 1892 205 Fd 15.8 12.1 1901 97 1901 206 Fd 5.5 4.5 93 93 1905 207 Fd 7.1 7.3 1902 96 1902 208 Fd 9.8 7.6 105 105 1893

Snag Fd 50.3 223 223 1775 209 Fd 8.6 7.5 102 102 1896 210 Fd 6.7 7.3 1908 90 1908 211 Fd 9.7 9.1 105 105 1893

Snag Fd 33.8 175 175 1823 212 Fd 43.8 19.5 1789 209 1789 213 Fd 46.3 21.2 1760 238 1760 214 Fd 48.9 22.0 1805 193 1805 215 Fd 12.4 9.2 113 113 1885 216 Fd 6.8 7.5 97 97 1901 217 Fd 9.4 6.3 1908 90 1908 218 Fd 9.6 7.1 105 105 1893

33

219 Fd 9.5 9.1 104 104 1894 220 Fd 7.7 7.5 1919 79 1919 221 Fd 11.5 10.5 1902 96 1902 222 Fd 10.0 9.2 106 106 1892 Log Fd 7.5 99 99 1899 Log Fd 8.9 103 103 1895 223 Fd 11.8 10.8 111 111 1887 224 Fd 12.0 10.1 1911 87 1911 225 Fd 10.1 10.2 106 106 1892 226 Fd 24.3 16.5 1898 100 1898 227 Fd 8.0 8.3 100 100 1898 228 Fd 12.0 11.3 1898 100 1898 229 Fd 10.5 10.8 1900 98 1900 230 Fd 17.9 13.6 129 129 1869 231 Fd 21.7 14.3 1899 99 1899 232 Fd 31.0 16.2 1812 186 1812 Log Fd 28.0 158 158 1840 233 Fd 7.1 6.5 97 97 1901 234 Fd 45.0 20.5 207 207 1791 235 Fd 37.2 20.3 1785 213 1785 236 Fd 23.8 16.8 1877 121 1877 237 Fd 24.0 16.6 1874 124 1874 238 Fd 16.2 14.5 124 124 1874 239 Fd 22.7 15.6 1854 144 1854 240 Fd 25.7 16.8 151 151 1847 241 Fd 22.5 15.2 1837 161 1837 242 Fd 14.9 13.1 1846 152 1846 243 Fd 20.4 15.0 1840 158 1840 244 Fd 23.0 16.1 1890 108 1890 245 Fd 7.6 7.5 99 99 1899

Snag Fd 8.1 100 100 1898 246 Fd 23.6 14.2 1858 140 1858 247 Fd 22.5 14.6 1885 113 1885 248 Fd 16.4 11.6 124 124 1874 249 Fd 15.8 11.3 123 123 1875 250 Fd 31.2 16.8 1844 154 1844 251 Fd 30.8 16.7 1862 136 1862 252 Fd 9.2 7.1 103 103 1895

Snag Fd 27.1 155 155 1843 253 Fd 5.9 5.7 94 94 1904 254 Fd 18.5 15.9 1845 153 1845 255 Fd 5.9 5.5 94 94 1904 256 Fd 12.3 12.5 112 112 1886 257 Fd 5.1 6.0 92 92 1906 258 Fd 8.4 8.5 101 101 1897 259 Fd 11.3 12.5 110 110 1888 260 Fd 6.3 5.5 1901 97 1901

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261 Fd 5.8 5.0 94 94 1904 262 Fd 5.1 4.7 92 92 1906 263 Fd 10.1 12.2 1906 92 1906 264 Fd 6.6 5.2 96 96 1902 Log Fd 40.0 193 193 1805 265 Fd 8.3 7.2 101 101 1897 266 Fd 6.4 6.1 95 95 1903 267 Fd 22.8 15.7 1888 110 1888 268 Fd 6.9 7.1 1905 93 1905 269 Fd 6.6 5.8 96 96 1902 270 Fd 14.9 12.2 120 120 1878 271 Fd 5.6 4.8 93 93 1905 272 Fd 7.8 9.5 1901 97 1901

Snag Fd 5.3 92 92 1906 273 Fd 9.4 7.7 104 104 1894 274 Fd 8.0 7.0 100 100 1898 275 Fd 7.7 8.5 1905 93 1905 276 Fd 11.0 10.5 109 109 1889 Log Fd 5.0 91 91 1907 277 Fd 12.1 10.5 1902 96 1902 278 Fd 8.5 8.6 101 101 1897 279 Fd 20.1 15.8 135 135 1863 280 Fd 21.1 16.0 1898 100 1898 281 Fd 8.9 10.0 103 103 1895 282 Fd 13.4 14.5 116 116 1882 283 Fd 34.7 16.0 1800 198 1800 284 Fd 6.0 6.0 1909 89 1909 285 Fd 6.3 6.3 95 95 1903 286 Fd 5.2 5.0 92 92 1906 287 Fd 5.4 7.1 1902 96 1902 288 Fd 5.4 6.3 92 92 1906 289 Fd 6.6 7.5 96 96 1902 290 Fd 7.6 8.2 1901 97 1901 291 Fd 7.0 7.2 97 97 1901 292 Fd 6.0 6.6 94 94 1904 293 Fd 9.0 11.2 1929 69 1929 294 Fd 7.7 9.0 99 99 1899 295 Fd 11.0 9.2 109 109 1889 296 Fd 55.4 19.5 1753 245 1753 297 Fd 5.0 4.5 1898 100 1898 298 Fd 7.0 7.8 1924 74 1924 299 Fd 9.5 8.5 104 104 1894 300 Fd 7.4 7.2 98 98 1900 301 Fd 10.0 9.5 1914 84 1914 302 Fd 5.8 5.1 1903 95 1903 303 Fd 15.5 13.5 122 122 1876 304 Fd 26.5 16.2 1869 129 1869

35

305 Fd 7.8 6.8 99 99 1899 Snag Fd 6.5 96 96 1902 306 Fd 25.1 17.3 1867 131 1867 307 Fd 11.7 7.8 111 111 1887 Log Fd 20.0 135 135 1863 308 Fd 5.5 6.7 93 93 1905 309 Fd 7.7 8.8 1899 99 1899 310 Fd 20.2 15.5 1878 120 1878 311 Fd 22.3 17.8 1878 120 1878 312 Fd 9.9 8.5 106 106 1892 313 Fd 24.7 18.5 1866 132 1866 314 Fd 10.9 8.0 1886 112 1886 315 Fd 27.1 16.5 1897 101 1897 316 Fd 32.3 17.3 1854 144 1854 317 Fd 17.3 12.3 127 127 1871 318 Fd 26.2 14.7 1853 145 1853 319 Fd 34.1 16.8 1869 129 1869

Snag Fd 7.4 98 98 1900 320 Fd 24.4 14.5 1867 131 1867 321 Fd 17.5 12.5 128 128 1870 322 Fd 23.9 14.3 1841 157 1841 323 Fd 19.7 13.8 1845 153 1845 324 Fd 49.9 21.2 1813 185 1813

Snag Fd 5.2 92 92 1906 Snag Fd 13.8 117 117 1881 325 Fd 30.8 18.0 1841 157 1841 326 Fd 5.7 5.7 93 93 1905 327 Fd 9.8 8.8 1910 88 1910

Snag Fd 5.4 92 92 1906 Snag Fd 5.3 92 92 1906 Snag Fd 5.1 92 92 1906 Snag Fd 8.3 101 101 1897 328 Fd 18.5 15.6 130 130 1868 329 Fd 8.5 8.5 101 101 1897 330 Fd 6.5 7.8 96 96 1902 331 Fd 10.3 11.5 107 107 1891 332 Fd 13.2 15.3 1902 96 1902 333 Fd 7.3 8.0 1899 99 1899 334 Fd 5.5 6.0 93 93 1905

Snag Fd 5.6 93 93 1905 335 Fd 9.7 12.2 105 105 1893 336 Fd 17.6 13.9 128 128 1870 337 Fd 13.1 13.8 115 115 1883

Snag Fd 7.5 99 99 1899 338 Fd 8.6 8.6 1901 97 1901 339 Fd 10.4 12.8 1900 98 1900 340 Fd 7.8 9.0 99 99 1899

36

341 Fd 10.2 10.1 106 106 1892 Snag Fd 8.0 100 100 1898 342 Fd 13.0 13.1 115 115 1883

37

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