I THINNING HIGHLY PRODUCTIVE LOBLOLLY PINE PLANTATIONS IN

THINNING HIGHLY PRODUCTIVE LOBLOLLY PINE PLANTATIONS IN THE SOUTHEASTERN US

Theresa Lynn Galinski B.S., North Carolina State University, 1999

A Non-Thesis Submitted in partial fulfillment of the requirements of the degree MASTER OF SCIENCE IN NATURAL RESOURCES (FORESTRY)

College of Natural Resources UNIVERSITY OF WISCONSIN Stevens Point, Wisconsin

June 2012

THINNING HIGHLY PRODUCTIVE LOB LOLLY PINE PLANTA TIO NS IN THE SOUTHEASTERN US

Theresa Lynn Galinski

APPROVED BY THE GRADUATE COMMITTEE OF:

Associate Professor of Forestry

~ /!,/IfI 2..o12-

Dr. Kevin Russell Date Associate Professor of Wildlife Ecology

11 ABSTRACT

Plum Creek is the largest private forestland owner in the United States with approximately 3.5 million acres located in the southeastern region. The majority of the forest is intensively managed plantations, of which the main species planted is loblolly pine (Pinus taeda L.). The harvest profile of these plantations includes a large portion of young stands ages 8-15 that are biologically at or approaching the need to be first-thinned in order to maintain growth and productivity. Due to genetic improvement, better competition control practices, and fertilization treatments deployed since the 1990’s, these younger stands are expressing an average site index value of over 80 feet (base age 25), which is considerably higher than older, less intensively managed plantations. As a result, these highly productive stands are reaching the self-thinning density limit at younger ages compared to stands with lower site index values. Age was typically used as a first-thin trigger in the past; however these younger stands may potentially lose live crown length at an earlier age.

Three loblolly pine plantations located in Liberty County, Georgia, were chosen based on high productivity rates with expressed site index values of 98, 99, and 102 feet, as well as young ages of 8, 10, and 9 years, respectively. Three 0.15-acre thinned and three un- thinned control plots were established in the 8- and 10-year-old stands, while only three thinned plots were established in the 9-year-old stand. The sample size and intensity was a compromise between the desire for larger plots balanced with available man power. Stands were operationally thinned in the summer of 2006.

All thinned plots as well as the 8-year-old un-thinned control averaged 10-11.75 of BA growth per year over four years since thinning regardless of thinning intensity, whereas the 10-year-old un-thinned control grew only 5.25 BA per year. This may be due to 19% mortality over four years in the 10-year-old un-thinned plots. Stand density index (SDI) values ranged from 60-66% before thinning for the 8- and 10-year-old plots, and both were thinned to 31% SDI. The 8-year-old thinned plots recovered to 47% SDI after four years, and the 10-year-old plots recovered to 44%. The 8-year-old un-thinned plots grew

iii

from 60 to 74% SDI which is above the reduced thinning response limit of 70%, while the 10-year-old un-thinned plots grew only from 65 to 69% SDI over four years, again most likely due to higher mortality. The 9-year-old stand was thinned to 20% SDI and recovered to 33% after four years. The 8- and 10-year-old stands were first-thinned at the appropriate time, based on the fact that the un-thinned plots are approaching the density- induced mortality limit by stand ages 12 and 14, respectively. An F-test showed that mortality, diameter, and basal area were all significant between thinned and un-thinned treatments at a 0.05 level.

Using Plum Creek’s proprietary growth and yield models, a comparison between four years of measured data and data modeled from the first year of thinning revealed a notable difference in trees per acre (TPA) and BA mainly in the un-thinned plots. Modeled TPA was 6-16% over measured and modeled BA was 6-24% over measured. Adjustments to the mortality function as well as a delayed thinning response have been made in the models based on the similarity of these study results to larger cooperative university studies.

Measured and modeled data for the thinned plots were used to analyze the value of a second thin. The financial analysis included several assumptions as well as a sensitivity analysis around discount rate and stumpage pricing. In all scenarios, a second thin to 75 residual BA was financially justified. The 9-year-old stand was not as financially optimal compared to the 8- and 10-year-old stands because of the heavy volume removals in the first thin, but a second thin was still financially justified over the one thin scenario.

A first-thin trigger using SDI appears to be more effective than stand age in terms of maintaining growth and minimizing volume losses to density-induced mortality. The second-thin provided positive financial retuns at various discount rates as well as stumpage pricing ranges. Further thinning research is needed in order to fine tune growth and yield models to reflect thinning response more accurately in plantations with expressed site index values greater than 80 feet.

ACKNOWLEDGEMENTS

Many thanks to Bill O’Brion and the Plum Creek crew in Tomahawk, Wisconsin, for being part of the beginning of this journey, and to Marshall Jacobson in Athens, Georgia, for insisting that I see this through to completion. I am also much obliged to my graduate committee, Drs. Jan Harms, Michael Demchik and Kevin Russell, for allowing me this opportunity and for providing constructive guidance to help me achieve my goal. And to my husband, Patrick Jolley, for giving me the creative space I needed and setting the example of achievement in his own life.

TABLE OF CONTENTS Page

ABSTRACT…………………………………………………………………………. iii

ACKNOWLEDGEMENTS …………………………………………………………….. v

LIST OF TABLES…………………………………………………………………… vii

LIST OF FIGURES…………………………………………………………………... ix

INTRODUCTION……………………………………………………………………. 1

LITERATURE REVIEW……………………………………………………………… 6

DESCRIPTION OF PROJECT AREA…………………………………………………... 13 Study Location……………………………………………………………. 13 Methods…………………………………………………………………… 14

RESULTS…………………………………………………………………………... 17 Stocking and Mortality……………………………………………………. 17 Diameter Growth………………………………………………………….. 17 Total Tree Height…………………………………………………………. 19 Basal Area………………………………………………………………… 20 Total Volume……………………………………………………………... 22 Stand Density Index………………………………………………………. 22 Data Results and Discussion……………………………………………… 24

COMPARISON OF MEASURED GROWTH TO MODELED GROWTH…………………… 25

OPTIMAL REGIME DEVELOPMENT – FINANCIAL ANALYSIS………………………... 31

CONCLUSIONS……………………………………………………………………... 38

LITERATURE CITED………………………………………………………………... 40

APPENDICES……………………………………………………………………….. 46

LIST OF TABLES Page 1. Varying stand density index values associated with three main stages of stand development according to three independent sources…………………………. 10 2. Age (years) at which measured plots at varying site index values and planting densities reached 57% and 70% SDI (PMRC Research) ……………………... 12 3. Stand establishment and silviculture treatment information for each study location………………………………………………………………………… 14 4. Trees per acre and mortality by stand and treatment type at each measurement period………………………………………………………………………….. 17 5. Average diameter in inches by stand and treatment type at each measurement period………………………………………………………………………….. 18 6. Total tree height in feet by stand and treatment type at each measurement period………………………………………………………………………….. 19 7. Basal area (ft2/acre) by stand and treatment type at each measurement period.. 21 8. Total volume (ft3/acre) by stand and treatment type at each measurement period………………………………………………………………………….. 22 9. Calculated average percent stand density index by stand and treatment type at each measurement period……………………………………………………… 24 10. Measured and modeled data for the 8-year-old thinned plots before thinning, after thinning, 2 years and 4 years after thinning……………………………… 26 11. Measured and modeled data for the 8-year-old un-thinned plots at initial measurement, 2 years and 4 years later……………………………………….. 26 12. Measured and modeled data for the 10-year-old thinned plots before thinning, after thinning, 2 years and 4 years after thinning……………………………… 27 13. Measured and modeled data for the 10-year-old un-thinned plots at initial measurement, 2 years and 4 years later……………………………………….. 27 14. Measured and modeled data for the 9-year-old thinned plots after thinning, 2 years and 4 years after thinning……………………………………………….. 28 15. Percent difference between modeled and measured data for trees per acre (TPA), basal area (BA), quadratic mean diameter (QMD), and average height. 28

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16. Range of stumpage pricing used in the financial analysis…………………….. 32 17. Financial analysis of the 8-year-old thinned plots, with values expressed as BLV ($/acre) with the rotation age in years in parenthesis……………………. 34 18. Financial analysis of the 10-year-old thinned plots, with values expressed as BLV ($/acre) with the rotation age in years in parenthesis……………………. 35 19. Financial analysis of the 9-year-old thinned plots, with values expressed as BLV ($/acre) with the rotation age in years in parenthesis……………………. 36

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LIST OF FIGURES Page 1. The average measured site index (base age 25) of loblolly pine plantations managed by Plum Creek in the southern US by establishment year from 1981 to 2002………………………………………………………………………… 3 2. Acreage of Plum Creek plantations by age that received various silviculture treatments as of 2010………………………………………………………….. 4 3. The number of plantation acres that were first-thinned from 2002-2009, and the number of harvest scheduled acres to be first-thinned from 2010 through 2024 (based on scheduled ownership as of 2010)…………………………….. 5 4. Trajectories of QMD (Dq) and TPA for measured loblolly pine plantations in the western Gulf region of the US…………………………………………….. 11 5. Study plots located near Riceboro in Liberty County in southeastern Georgia.. 13 6. Average DBH by stand and thinning treatment before thinning, after thinning, then two and four years after thinning………………………………………… 18 7. Average total basal area by stand and thinning treatment for each measurement period…………………………………………………………… 21 8. Quadratic mean diameter (QMD) plotted with corresponding TPA by stand and by thinning treatment for each measurement period……………………… 23

INTRODUCTION

Objectives Loblolly plantations with expressed site index (SI) values above 80 feet (base age 25) are developing faster than traditional stands with lower site index values, and are reaching the self-thinning limit much sooner. Resource managers are not accustomed to conducting first-thins in stands less than 15 years of age, and so this new cohort of young, fast growing plantations are potentially losing productivity because of density-induced mortality. Also, some have argued that the traditional two-thin regime for intensively managed loblolly pine plantations in the southeastern US may not be financially optimal in high productivity stands. High growth rates coupled with the current low solid-wood stumpage pricing may yield better financial returns with a one-thin regime compared to a two-thin regime.

This study had two objectives: first, to show that timing a first-thin in highly productive loblolly plantations based on stand density index (SDI) and not stand age reduces tree mortality and captures more stand growth potential. Second, to evaluate whether a two- thin regime provides better financial returns compared to a one-thin regime.

Three stands in southeastern Georgia were selected based on expressed site index values, which ranged from 98 to 102 feet. A comparison between the measured and modeled data was performed in order to evaluate any major variances in future growth and yield projections. Then, based on four years of measured data plus modeled data for the rest of the rotation, a financial analysis was completed using a range of discount rates as well as a range of stumpage pricing to determine the rotation with the highest bare land value (BLV).

Background Plum Creek owns approximately 3.5 million acres of timberlands in the southeastern US, within the states of North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Arkansas, Louisiana, and Texas. Of that acreage, about 71% or 2.5 million

acres are intensively managed pine plantations of which loblolly pine (Pinus taeda L.) is the predominant species.

Pine plantation management in the southeastern US has transformed from a relatively extensive system of planting with minimal silviculture treatments in the 1950’s to the more intensive management regimes of today. Plantation management now includes advanced genetic tree improvement, site specific competition control and nutrition management which have greatly increased stand productivity and economic returns (Munsell and Fox 2010). As a result, the site index values of pine plantations have steadily risen from an average of 50 to 60 feet (base age 25) to 70-80 feet with some current plantations expressing site index values greater than 90 feet. The current typical rotation of planted loblolly pine includes: • Mechanical site preparation if needed to improve soil drainage or manage debris • Chemical site preparation to control woody vegetation (brush, hardwoods, vines) • Herbaceous weed control treatment(s) to control weeds and grasses • Strategic seedling deployment to maximize genetic gains from tree improvement • Age 2-8: Pre-commercial thin if natural pine has seeded into stand, and/or chemical release if woody competition was not adequately controlled during site preparation • Age 10-15: A first commercial thinning followed by a fertilization of nitrogen (N) and phosphorous (P) • Age 16-21: A second commercial thinning followed by a fertilization of N and P • Age 22-30: A final clear-cut harvest generally 5 to 7 years after the second thin

In terms of the contribution of each component of intensive management to productivity, competition control through chemical site preparation can increase overall yields by as much as 20-30 tons per acre with a height response of 2-4 feet. Herbaceous weed control also has a similar impact, adding 20-30 tons per acre over the rotation and 2-4 feet of height response (PMRC, Multiple Studies). Each mid-rotation fertilizer treatment generally results in 8-12 tons per acre of increased yield with a height response of approximately 2 feet (FPC, Multiple Studies). Plum Creek’s internal tree improvement

program has made significant progress over the past 15 years, and the genetic gain of the average deployed seedlots ranges from 3-5 feet of expressed site index for stands 10-15 years of age to 10-15 feet for stands planted within the past 2 years (Belonger 2012).

These advancements in southern pine plantation management have resulted in the younger generation of plantations growing at faster rates than older plantations. In an effort to understand these growth dynamics and how they may impact current management recommendations, Plum Creek quantified its current pine plantations by age and expressed site index values (Figure 1). Site index values were calculated from the most recent timber cruise data. As a result of more intensive silviculture treatments and more advanced genetic sources, 10 to 15 year old stands are growing on average at higher site index rates of 75 to 81 feet compared to their older counterparts.

85 81 80

70 65

Site Index Site Index (feet, base age 25) 65

Plantation Establishment Year Figure 1: The average measured site index (base age 25) of loblolly pine plantations managed by Plum Creek in the southern US by establishment year from 1981 to 2002.

This site index shift is a direct effect of conducting more targeted and intensive silviculture techniques as well as improved genetics. Plantations that are currently older than 15 years tended to receive only mechanical site preparation before planting and were minimally treated with herbicides to control competing vegetation. Most stands received some fertilization treatments, though stands greater than 25 years old generally did not. In contrast, stands less than 15 years of age have nearly all been treated with herbicides through chemical site preparation and early herbaceous weed control efforts in order to 3

control competing vegetation and have received fertilization treatments to mitigate nitrogen and phosphorous deficiencies (Figure 2). Fertilization treatments have increased in the last 15 to 20 years in terms of total acres treated, and applications are more effectively implemented with respect to target stand ages and soil types.

160,000

140,000 Thin #1 Thin #2 120,000

100,000 Clearcut 80,000

60,000

40,000 Plantation Acres 20,000

- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Current Age ...... PL Acres HWC Fert ChemSP MechSP

Figure 2: Acreage of Plum Creek- plantations by age that received herbaceous weed control

(HWC), fertilization (Fert), chemical site preparation (ChemSP), or mechanical site preparation

(MechSP). “PL Acres” refers to the number of acres planted in each year. Thin #1, Thin #2, and Clear-cut arrows indicate the current average age at which those activities generally occur (internal data from 2010).

The faster growth rates coupled with the influence of tree density affect the timing and possibly the intensity of the first thinning. Stands are scheduled for a first thinning based on merchantable volume and stand density index (SDI), which takes into account trees per acre and basal area. The timing of the first thin is not based on stand age. After reviewing the current inventory and projected harvest levels for the southern ownership, there is gradual increase of acres over the next two years scheduled to be first-thinned followed by a sharp rise of acres in 2013 (Figure 3). These increased acreages per year scheduled for first thinning will remain above current levels into the foreseeable future. Over the next 15 years, approximately 1.4 million acres of plantations will need to be 4 first-thinned which presents an opportunity to reset stand density levels to achieve expected productivity rates and maintain company harvest levels. This population of young stands is expressing site index values of 75-85 feet on average, which presents the questions of how does site index affect stand development and are the current assumed regimes maximizing financial returns.

120,000

100,000

80,000

60,000 Acres

40,000

20,000

Year

■ Actual ■ Scheduled

Figure 3: The number of plantation acres that were first-thinned from 2002-2009, and the number of harvest scheduled acres to be first-thinned from 2010 through 2024 (based on

scheduled ownership as of 2010).

Plum Creek foresters in the southeastern US are accustomed to working with the older plantations and make certain management assumptions that are not applicable to the younger generation of plantations. This has prompted the Operations Support Group of the company to take a closer look at how resource foresters should approach first thinning operations in the younger, faster growing plantations. Not only the timing of the thinning, but also a more thorough evaluation of the triggers used to determine the stages of stand development such as stand density index (SDI), basal area (BA), live crown ratio, and trees per acre (TPA). 5

LITERATURE REVIEW

Loblolly pine is a shade intolerant species that expresses dominance and begins to self- thin when a stand completely occupies its growing space (Schultz 1997). It is generally managed on an even-aged basis with thinning treatments to manage stand density and allocate growth to the crop trees, and to provide intermediate cash flows for higher economic returns. Thinning includes five fundamental methods – thinning from below, thinning from above or crown thinning, selection thinning, geometric/mechanical (row) thinning, diameter-limit thinning, and free thinning which can include a combination of thinning treatments (Smith et al 1997). For the most part, loblolly pine plantations in the southeastern US are thinned by using the low, selection, mechanical or row, and crown thinning methods to various degrees and combinations. Regardless of the method chosen or whether the treatment is conducted commercially or pre-commercially, the optimal result of a thinning treatment is to retain vigorously growing crop trees at a spacing that releases their live crowns to provide optimal stem growth throughout the rotation. Thinning a plantation too early will reduce overall stand yield and merchandize the future growing stock too soon in the rotation. Thinning too late suppresses or eliminates the tree response to thinning (Dean and Baldwin 1993).

Thinning research has mostly focused on individual tree response at various levels of thinning intensity. Zahner and Whitmore found that the fewer residual stems after thinning, the longer the effect of release from competition (1960). The thinned trees maintained a more vigorous growth rate for a longer period of time. Burton deduced that a heavier thinning allocated the highest growth to the best trees without sacrificing form class, whereas tree growth in the lightly thinned plots was hampered by competition and crown reduction (1977). Total volume growth was higher with the light thinning, but the growth was distributed over more trees with a smaller diameter. Although thinning generally does not increase the overall volume of the rotation, it does increase the total volume growth of the thinned trees (Amateis et al. 1996). Hartsell noted that the un- thinned plots exhibited 2.2% per year of average annual volume growth of all live trees, while plots in thinned stands grew 4.6% per year (2009). It has also been theorized by

several that thinning increases the health and vigor of a stand by removing smaller, slower growing, and diseased trees. Short and Burkhart discovered that thinning does slow the recession of crown height compared to an un-thinned counterpart, which would increase tree growth and vigor (1992). Brown studied the effect of thinning on resistance to bark beetle attacks, finding that thinned trees responded to thinning with greater diameter growth and oleoresin exudation pressure (1987). Resistance to southern pine beetle was greater in stands thinned to 100 BA or less compared to the no-thin control.

Economic advantages of thinning include early financial returns during the rotation, improvement of wood product quality, more diversified wood products, and risk reduction by increasing stand vigor and reducing volume loss to density-induced mortality (Smith et al. 1997). Thinning removes almost all pulpwood trees from the larger diameter classes, which helps to shift the product distribution towards higher valued product classes (Amateis and Burkhart 2005). Therefore, thinning can be scheduled based on financial return analysis. Schultz set forth that a first thin is best optimized when approximately 36% of the total loblolly pine growing stock is in the 6-10 in diameter classes (1997).

Though thinning in loblolly pine plantations has long been a topic of research, site index has rarely been taken into account. In terms of plantation thinning research, most major cooperative studies were established in stands with lower site index values ranging from less than 60 to no more than 75 feet (FPC and PMRC). Stands expressing site index values above 80 feet are therefore not well understood at this point in terms of published research. It has been assumed that the mechanics of individual tree response are the same regardless of site index, but that stand development occurs faster for a stand with a higher site index value. Harrington surmised that stands with a higher expressed site index undergo self-thinning more rapidly and track closely below the self-thinning line as quadratic mean diameter increases (2001).

Belanger and Brender evaluated 42 quarter-acre plots established in loblolly pine plantations on a range of sites located in central Georgia (1968). The plantations were 19

years of age when the measurements were taken, and at that point the stands had no cultural treatments applied beyond burning and planting in 1940. Site index values ranged from 66-112 feet, base age 50, which is approximately 40-75 feet at base age 25. The stands were thinned with various methods and the authors concluded that as site index increased, so did basal area, diameter, and merchantable volume in terms of growth responses to thinning. It is interesting to note that site index measurements were not directly discussed in the article, nor were height measurements before and after treatment. However, these site index values are below the current plantation average on Plum Creek land and the management regimes were far less intensive than what is operational today. Also, most of the stands had high densities compared to current management with trees per acre (TPA) well above 700 at age 19.

Huang and Kronrad noted that as site index increases, the timing of the first thinning decreases due to stands approaching the upper growing-stock limit sooner (2002). They found that a stand expressing a site index of 90 feet could be thinned as early as 11 years of age, while stand with a site index of 50 feet can be left until as late as 33 years of age in biological terms. This study was conducted by developing a dynamic programming approach that utilized growth and yield modeled scenarios instead of empirical field data.

Radtke and Burkhart experimented with basal area growth and crown closure timing in a loblolly pine spacing trial, and also examined the effects of site index on those variables (1999). Annual growth data through age 13 was used from four research installations in stands with expressed site index values of 60, 63, 66, and 72 feet (base age 25). They examined the inflection age of basal area development, which is defined as the point in time when the crowns close and inter-tree competition begins to slow basal area growth. This point of basal area inflection generally occurred sooner on study sites with higher site index values, though there were exceptions to this observation. This could be attributed to the fact that the range of total tree heights was narrow between sites. Crown competition also increased with site index, which may indicate more tree vigor on sites with higher index values.

In terms of specific thinning prescriptions, Schultz suggests that stands with a higher site index value should be thinned to 78 BA (ft2/acre) when density reaches 109-122 BA. Stands with greater than 148 BA will not achieve maximum growth potential. Stands on poor sites should be thinned back to 70 BA when density reaches 91 BA (Schultz 1997). This recommendation lends to the theory that more highly productive sites reach the upper growing-stock limit in less time than lower productivity sites if density is consistent.

First thinning research conducted recently on red pine plantations in northern Michigan on Plum Creek timberlands found that the diameter class distribution shift in the response to thinning was greatest in the younger high site index plantations (Wyckoff 2011).

Another measure used to quantify stand development in even-aged stands is stand density index, or SDI. The concept of SDI was originally put forth by Reineke as a tool to measure how density impacts the diameter growth of a stand (1933). This index is a better measure of stand density because it is does not have the short comings of BA or TPA alone, and it is independent of age and site quality (Harrington 2001). Site quality has not been found to influence the maximum SDI of a given species; though it may impact the time it takes a stand to reach a maximum SDI which does vary by species.

The premise of SDI is that there is an upper limit to stand density as a function of both the number and size of trees, expressed as 100% SDI. At that point in development, the stand cannot increase diameter growth without tree mortality which reallocates resources to the remaining trees (Dean and Baldwin 1993). Mortality is not directly caused by stand density, but rather high stand densities cause a decline in tree vigor (Drew and Flewelling 1979). SDI is calculated by using TPA and the quadratic mean diameter (QMD) of a stand at a given point in time: . = ---- 10 1 6 푄푀퐷 푆퐷퐼 푇푃퐴 ∗ � �

QMD is the diameter of the tree with the mean basal area of the stand, and can be calculated as follows: .

= 0 5 0.005454퐵퐴 � � 푄푀퐷 � 푇푃퐴 �

where BA is measured in ft2 per acre, TPA is number of trees per acre, and QMD is calculated in inches.

There are three main stages of stand development: crown closure or full site occupancy, the self-thinning or the density-induced mortality limit, and the maximum tree size- density limit. Decline in tree vigor begins near the self-thinning limit and continues to accelerate as the stand approaches the maximum tree size-density limit (Williams 1994). There is some variation among researchers as to what value of SDI corresponds with each of these phases of development for loblolly pine (Table 1).

Table 1: Varying stand density index values associated with three main stages of stand development according to three independent sources. Williams (1994) Dean and Baldwin (1993), Harrington (2001) Crown Closure 160 (40% Max SDI) 113 (25% Max SDI) Density-Induced Mortality 220 (55% Max SDI) 225-248 (50-55% Max SDI) Maximum SDI 400 450

Decline in tree vigor becomes evident as the stand develops beyond the self-thinning line and approaches the maximum size-density limit (Figure 4). A first thinning should be implemented at the point in time before stand growth begins to slow due to density- induced mortality and high competition between tree crowns, depicted by Line B in Figure 4. This point in stand development can be influenced by initial planting density, genetics, seedling survival, disease and pest issues, weather, soil type, and the rate of growth (Dean and Baldwin 1993).

When determining a thinning schedule for loblolly pine plantations, three factors are commonly considered: 1) the target average diameter of the stand at rotation age, 2) the upper growing-stock limit (or density-induced mortality limit), and 3) the lower growing- stock limit (Dean and Baldwin 1993). Thinning has both biological and financial implication in terms of timing, intensity, and frequency. 10 9 Volume growth expressed as periodic 8 ffi annual increment increases rapidly to r5 1 ~ 6 the density-induced mortality limit, C "' 5 peaks at about 70% of maximum SDI 4 and begins to decline as SDI 3 continues to increase (Dean and Baldwin 1996). Therefore, the timing of the first thin should maintain stand '100 1,000 TREES Pm ACRE density in between the lower Figure 4: Trajectories of QMD (Dq) and TPA for growing-stock limit or crown closure measured loblolly pine plantations in the western phase and the upper growing-stock Gulf region of the US. Line A is the tree size-tree limit with live crown ratio begins to number boundary or maximum SDI of 100%, and decline. While the first thin tends to Line B is the threshold of the density related mortality or 70% SDI (Dean and Baldwin 1993). be more of a biological decision to maintain forest productivity, subsequent thinning will tend to be driven more by economic value and cash flow opportunities.

For the purpose of this analysis, the following assumptions of SDI values for loblolly pine are used: • Lower growing-stock limit or crown closure: 34%, or 170 SDI • Upper growing-stock limit or first-thin trigger: 57%, or 285 SDI • Reduced thinning response or self-thinning limit: 70%, or 350 SDI • Maximum SDI: 500

The Plantation Management Research Cooperative (PMRC) of the University of Georgia installed a long-term, region-wide study to test the effects of stand density and intensive management on loblolly pine growth and yield, commonly referred to as the Culture x Density study. Planting densities ranged from 300 to 1800 TPA in increments of 300, while silviculture treatments included an operational and intensive level. At age 15, several of the installations expressed maximum SDI values for loblolly pine of 450 to 500 SDI at both silviculture intensity levels, which indicated that more effective competition control and more advanced genetics can increase the maximum tree size-density limit. Therefore, it was internally decided that with current intensive management coupled with advanced tree improvement, the maximum SDI value would be more applicable at 500 rather than 450. Also, the initial range of maximum SDI measured for loblolly pine was based primarily on natural stands (Taylor 2012).

Finally, the PMRC Culture x Density study as well as other spacing studies has demonstrated that higher productive stands reach the self-thinning density limit sooner than stands at lower site index values. For example, at 600 TPA the average plot data from sites expressing 72 feet of SI crossed 57% SDI at age 12 while sites growing at 85 SI reached that same point at age 8. Density-induced mortality begins to occur at or near 70% SDI, which plots expressing 72 SI approached by age 18 and plots at 85 SI crossed by age 12. Tree density also has an impact on the timing of stand development in terms of SDI, where the higher the density the sooner the stand advances through the stages of stand development (Table 2).

Table 2: Age (years) at which measured plots at varying site index values and planting densities reached 57% and 70% SDI (PMRC Research). Expressed Site Index (feet): 72 85 TPA: 450 600 750 400 600 800 Upper-Growing Stock Limit (57% SDI) 17 12 11 9 8 7 Self-Thinning Limit (70%) 22 18 15 15 12 10

DESCRIPTION OF PROJECT AREA

Study Location Research plots were installed in three loblolly pine plantations located in Liberty County in southeastern Georgia on Plum Creek timberlands near the town of Riceboro (Figure 5). The stands were chosen based on high productivity rates with expressed site index values ranging from 98, 99, and 102 feet (base age 25), as well as younger ages of 8, 10, and 9 years, respectively. These ages were younger than the locally accepted first thinning age by 3-5 years at the time this study was initiated.

10 Georgia

Plum Creek Ownership

Figure 5: Study plots located near Riceboro in Liberty County in southeastern Georgia. Numbers refer to the age of each stand and represent their locations. The soil series associated with the 8-year old stand are Bladen and Eulonia fine sandy loams that are somewhat poorly drained with a fine textured clay horizon greater than 20” from the soil surface. The 10-year old stand is located on a mixture of Bladen fine sandy loam and Mascotte fine sand, while the 9-year old stand is located on a combination of Riceboro fine loamy sand and Mascotte fine sand. All three locations are typified as somewhat poorly to poorly drained sandy loams.

Prior to seedling establishment, all three stands were sheared with a KG blade that removes stumps and logging debris which is then piled into long strips or windrows. The 8- and 9-year-old stands were disked in order to ameliorate compaction. Because the soil types are somewhat poorly to poorly drained, all three stands were double bedded in order to increase the available oxygen and reduce seedling mortality due to poor drainage (Smith et al. 1997). The 8- and 9-year-old stands were then treated with an imazapyr site prep herbicide to control hardwood and woody brush competition, while the 10-year-old stand was not treated. All stands were planted in January the year after site preparation, and all three stands were treated the following spring with pre-emergent herbicides to control broad-leaved weeds and grasses. After establishment, all three stands were fertilized with di-ammonium phosphate (DAP) within 4 years of planting. Finally, all stands received a pre-merchantable fertilization treatment of DAP and Urea between 5 and 10 years after establishment (Table 3).

Table 3: Stand establishment and silviculture treatment information for each study location. Age at Mechanical Site Chemical Site Prep + Planting Thinning Prep Herbaceous Weed Control Date Fertilization(s) Shear, Disk, Imazapyr Site Prep (‘97) DAP (‘98) 8 1/13/98 Double Bed (‘97) Hexazinone + Sulfometuron (‘98) DAP+Urea (‘03) Shear, Double No Chemical Site Prep DAP (‘00) 10 1/15/96 Bed (‘95) Sulfometuron (‘96) DAP+Urea (‘06) Shear, Disk, Imazapyr Site Prep (1996) DAP (‘97) 9 1/15/97 Double Bed (‘96) Hexazinone + Sulfometuron (‘97) DAP+Urea (‘04)

Methods Because resource foresters at the time were using stand age as a first-thinning trigger, the younger cohort of plantations with higher productivity rates were not being evaluated for potential thinning harvests. This was becoming a much larger issue given that there were a greater proportion of acres each year reaching self-thinning density limits and potentially losing productivity. The purpose of installing these study plots was two-fold: first, to bring awareness to the above issue among resource foresters and managers, and also to have an operational thinning research study in stands with higher than normal expressed site index values in order to evaluate long term growth and yield. From the 14

response data, a regime analysis can be conducted in order to determine what ranges of thinning intensity and timing will maximize financial returns.

The plots are 0.15 acres in size and were installed in July and August of 2006. Rectangular plot dimensions average 72 feet in width by 91 feet in length. Three replications of thinned and un-thinned treatments were installed in the 8- and 10-year old plantations, while only three thinned plots were established in the 9-year old plantation. This third stand was added after the fact, and had already been operationally thinned before un-thinned control plots could be established.

Within the 8- and 10-year-old stands, all trees were tallied and measured in all plots prior to thinning in 2006, immediately after thinning, after two growing seasons in February of 2009, and again after four growing seasons in September of 2010. In the 9-year-old stand, plots were established after thinning and so were measured post-thinning but then followed the same measurement schedule as the 8- and 10-year-old stands. Trees per acre (TPA), diameter at breast height in inches (DBH), and total height in feet were measured at each period. From this data, tree mortality, basal area in square feet per acre (BA), total volume, and stand density index (SDI) were also calculated. Statistical analysis included an F-test to compare thinned plots to un-thinned plots of the 8- and 10- year-old plots with significance at or below the 0.05 level.

The measured plot size was based on current research being conducted by the Plantation Management Research Cooperative (PMRC), where 0.10-0.15 acres plots were used in a long-term culture x density study for the 600 and 900 TPA plots which coincides closely with the before and after thinning stand conditions. The Forest Productivity Cooperative (FPC) also has an active thinning study in which the same size plot range is being used for plots with 300 TPA or more. Regrettably, the total sample size is small compared to the above region-wide studies. Only two of the three stands have un-thinned control plots from which comparisons of stand development can be made with and without thinning. The number of plots and replications were mainly based on available man- power and what could be accomplished in time before the stands were operationally

15 thinned. In addition, this study was established on only one type of soil group in one physiographical region which will limit any extrapolation of this data onto different soil groups as well as different regions.

All stands were operationally thinned from below with the contractor focused on removing trees with defects such as fusiform rust galls on the bole, forked tops, crooked form, and suppressed trees, while leaving the largest and most healthy crop trees. Thinning intensity for the 8- and 10-year-old stands was based on a target residual of 30- 35% SDI, and so both stands were thinned to 71 and 75 ft2/acre of BA respectively. The 9-year old stand was thinned to a lower basal area of 46 ft2/acre or 20% SDI, mainly to observe if stand growth and development were negatively impacted by reducing density below acceptable stocking levels by comparing to the 8- and 10-year-old thinned plots. The thinning method was chosen based on balancing harvest yields per acre with the target SDI, and so every third row was removed with selective thinning done within the leave rows to reach the residual targets.

RESULTS

Stocking and Mortality Thinning represents a basic silviculture tool used to salvage expected losses of merchantable volume due to decline of tree vigor and to increase value from improved diameter growth of the residual crop trees (Smith et al. 1997). In the 8-year old stand, there was no mortality in the thinned plots during the four years after thinning while the un-thinned plots experienced 12% mortality. The 10-year old stand exhibited 4% mortality four years after thinning, while the un-thinned plots suffered from 19% mortality. The 9-year old stand lost 2% of trees per acre over four years (Table 4).

Table 4: Trees per acre and mortality by stand and treatment type at each measurement period. Total and percent mortality indicates total loss since thinning. (*F-values less than 0.05 indicate significant difference between thinned and un-thinned.) Total % Stand Treatment Before Removals After 2 Yrs. 4 Yrs. Mortality Mortality 8-yr old Thinned 656 331 325 325 325 0 0% 8-yr old Un-thinned 644 0 644 593 569 76 12% F-test 0.115 0.005* 0.004* 0.004* 0.042* -- 10-yr old Thinned 613 355 258 251 249 9 3% 10-yr old Un-thinned 605 0 605 527 489 116 19% F-test 0.638 0.001* 0.001* 0.001* 0.001* -- 9-yr old Thinned -- -- 216 211 211 5 2%

In the 8-year old stand, 331 trees were removed leaving 325 TPA or 50% of the initial stocking. The 10-year old stand had 42% of the initial stems removed, dropping the stand density from 613 to 355 TPA. The pre-thin condition of the 9-year old stand was not measured, though there were 216 TPA after thinning.

Diameter Growth All stands were thinned from below which can slightly increase the average diameter, though only the thinned plots in the 10-year old stand were significantly greater than the

un-thinned plots. The thinned 9-year-old plots averaged 6.2 inches, similar to the average diameter of the 8-year-old thinned plots (Table 5).

Table 5: Average diameter in inches by stand and treatment type at each measurement period. (*F-values less than 0.05 indicate significant difference between thinned and un-thinned.)

~ I I Total Growth Diameter Response Stand Treatment Before After 2 Yrs. 4 Yrs. over 4 Yrs. (% over 4 yrs.) I I I I - 8-yr old Thinned 6.0 6.2 7.2 7.9 1.7 27% I I I l - 8-yr old Un-thinned 6.1 I 6.1 I 6.9 I 7.4 1.3 21% l - ' F-test 0.013* 0.256 0.075 0.049* 0.090 -- - 10-yr old Thinned 6.7 7.2 8.3 9.1 1.9 26% J l l J - 10-yr old Un-thinned 6.6 6.7 7.4 7.9 1.2 18% l - F-test 0.735 0.014* 0.042* 0.035* 0.063 -- J l l ' 9-yr old Thinned -- 6.2 7.6 8.4 2.2 35% I l l l J

Tree diameter is negatively correlated with stand density (Schultz 1997). When stand density is decreased as with a thinning treatment, the average diameter growth should increase over the un-thinned counterpart. Both the 8- and 10-year-old plots had significant diameter response over four years of growth in the thinned plots compared to the un-thinned plots (Figure 6).

9.5 9.0 8.5 Unthinned 8-yr-old

8.0 Thinned 8-yr-old

7.5 Unthinned 10-yr-old 7.0

DBH (inches) Thinned 10-yr-old 6.5 Thinned 9-yr-old 6.0 5.5 Before Thinning After Thinning 2 Years 4 Years

Figure 6: Average DBH by stand and thinning treatment before thinning, after thinning, then two and four years after thinning.

The 8-year old thinned plots added 1.7 inches of diameter growth in four growing seasons whereas the un-thinned plots only averaged 1.3 inches. The 10-year old thinned plots responded an average of 1.9 inches while the un-thinned plots added 1.2 inches of diameter growth. The 9-year old plots grew on average 2.2 inches.

Percent diameter growth over four years in the thinned plots was fairly similar for both the 8- and 10-year old stands which averaged 27% and 26%, respectively. However, the 9-year-old plots exhibited 35% diameter growth over four growing seasons. The 8- and 10-year-old un-thinned plots averaged 18% and 21% of diameter growth over four years, respectively.

Total Tree Height Stand density does not impact tree height to the same degree as tree diameter, so thinning has very little effect on average stand height for loblolly pine except in stands where overcrowding is severe (Brooks and Bailey 1992). If there is a detectable difference, the magnitude and duration of the thinning response on tree height growth is related to thinning intensity, site quality (site index) and tree vigor (Zhang, Burkhart, and Amateis 1997). Over four growing seasons, height growth variation between the thinned and un- thinned plots was not significantly different (Table 6).

Table 6: Total tree height in feet by stand and treatment type at each measurement period. (*F-values less than 0.05 indicate significant difference between thinned and un-thinned.) Before After Stand Treatment Thinning Thinning 2 Years 4 Years Total Growth over 4 Years 8-yr old Thinned 39.8 40.8 50.1 57.5 16.7 8-yr old Un-thinned 41.8 41.8 52.1 59.9 18.0 F-test 0.097 0.352 0.118 0.154 0.177 10-yr old Thinned 52.4 53.5 60.0 66.7 13.1 10-yr old Un-thinned 54.1 54.1 61.6 68.4 14.3 F-test 0.421 0.740 0.378 0.364 0.463 9-yr old Thinned -- 46.0 52.6 57.2 11.2

Basal Area Basal area growth after a thinning is dependent upon several factors, including residual tree density, site quality, tree health and vigor, and stand age. This fact alone makes comparing basal area growth from one study to another difficult. However, basal area remains a valuable tool when detecting tree growth response to thinning (Hasenauer et al. 1997). Guttenberg noted in his thinning study that basal area growth after thinning was not correlated to the percent basal area removed (1954). Hasenauer and others also showed this to be true as the lightly thinned and the heavily thinned plots both grew an average of 4.5 ft2/acre/year in 12 years after thinning (1997). A similar review of 121 study locations across the southeast showed the same trend with lightly thinned plots averaging 4.9 ft2/acre/year over 12 years and the heavily thinned plots averaging 4.8 ft2/acre/year. Another concept put forth by several researchers is that the basal area of the thinned stand will approach the basal area of the un-thinned stand (Hasenauer et al. 1997). Therefore, total basal area growth of thinned stands is greater than that of un- thinned stands with similar conditions over the same period of time (Brooks and Bailey 1992), though it is curious to note that was not the case in the 8-year-old study site (Table 7). Heavier thinning will take more time for BA of the thinned plots to approach the un- thinned control, and higher site index stands that are thinned lightly result in faster BA recovery in relation to their un-thinned counterparts (Amateis 2000). Stands that are released through thinning approach but do not actually converge with the BA of a stand planted at the same density as the residual thinned stand (Harrington 2000).

The basal area growth of the 8-year old stand was similar between the thinned and un- thinned plots, while the growth of the 10-year old thinned stand was twice as much as its un-thinned counterpart. This difference does not meet the statistical significance level of 0.05. However, the lower basal area response in the 10-year-old stand may be related to the higher mortality of 19% compared to 12% total mortality in the 8-year-old un-thinned plots. The 10-year-old stand initially had 153 BA while the 8-year-old stand started at 135 BA, which is mainly due to the two-year age difference (Table 7).

Table 7: Basal area (ft2/acre) by stand and treatment type at each measurement period. (*F-values less than 0.05 indicate significant difference between thinned and un-thinned.) Before After Total Stand Treatment Thinning Removals Thinning 2 Years 4 Years Growth 8-yr old Thinned 134 63 71 96 118 47 8-yr old Un-thinned 135 0 135 159 180 45 F-test 0.467 -- 0.002* 0.003* 0.005* 0.660 10-yr old Thinned 154 79 75 96 115 40 10-yr old Un-thinned 153 0 153 162 174 21 F-test 0.688 -- 0.001* 0.012* 0.021* 0.087 9-yr old Thinned -- -- 46 68 86 40

It is also interesting to note that all thinned plots grew on average 10.0-11.8 ft2/acre/year of basal area, regardless of age and thinning intensity (Figure 7). This is consistent with the findings from a study conducted on an old field site with an average site quality at age 25 of 80 feet. The average annual BA growth 10 years after thinning did not vary significantly by thinning intensity and were greater than the un-thinned control (Xydias et al. 1982). However, the annual BA growth of the thinned plots ranged from 4.9 to 5.4 ft2/acre/year which is well below the response recorded in this study.

180

160 Unthinned 8-yr-old

140 /ac)

2 Thinned 8-yr-old 120 ,, ...... Unthinned 10-yr-old 100 ' _ )I( ... Thinned 10-yr-old 80 Basal Area (ft Area Basal Thinned 9-yr-old 60 .,,,,,,, ~ 40 Before Thinning After Thinning 2 Years 4 Years

Figure 7: Average total basal area by stand and thinning treatment for each measurement period.

Total Volume Volume growth does not provide a fair evaluation of thinning methods, because total yield over a rotation is generally less with a thinning regime versus a no-thin regime (Smith et al. 1997). Except on sites with high initial stem densities (>2000 TPA), maximum total volume growth occurs on un-thinned stands until natural mortality of the suppressed trees occurs (Brooks and Bailey 1992). If the goal is to maximize total volume growth, most research has found that it is best to conduct light, frequent thinnings which keep the crown competition at a moderate level to minimize mortality from suppression (Mann 1952). Heavier thinnings can produce a higher percentage of sawtimber volume later in the rotation while sacrificing volume growth. Both the 8- and 10-year-old plots had greater total volume growth in the un-thinned plots compared to the thinned plots (Table 8). The un-thinned 8-year-old plots grew a total of 837 ft3/ac or 19% more than the thinned plots, while the un-thinned 10-year-old plots grew only 221 ft3/ac or 4% more than the thinned counterpart. This trend is similar to basal area growth, which is intuitive as volume growth is driven mainly by diameter growth.

Table 8: Total volume (ft3/acre) by stand and treatment type at each measurement period. (*F-values less than 0.05 indicate significant difference between thinned and un-thinned.) Total Total Growth Stand Stand Treatment Before Removals After 2 Yrs. 4 Yrs. over 4 Yrs. Volume 8-yr old Thinned 2441 1121 1320 2230 3222 1902 4344 8-yr old Un-thinned 2589 0 2589 3895 5181 2593 5181 F-test -- -- 0.004* 0.004* 0.004* 0.029* 0.006* 10-yr old Thinned 3812 1958 1854 2670 3585 1731 5542 10-yr old Un-thinned 3937 0 3937 4786 5763 1826 5763 F-test 0.437 -- 0.006* 0.016* 0.027* 0.737 0.396 9-yr old Thinned -- -- 977 1645 2307 1329 --

Stand Density Index Diameter growth trajectory of this study was negatively impacted by stand density, as show in Figure 8. Note that the un-thinned plots seem to be tracking closely with the 70% SDI line as Dean and Baldwin indicated through their research (1996). The thinned

22 plots four years after thinning are still growing with very little diminution due to density. All three thinned sites were harvested to below the lower growing-stock limit of 34%, with the 9-year-old stand thinned well below that limit to 20% SDI. The 8- and 10-year old stands crossed over the lower growing stock-limit within two years after thinning, while the 9-year old stand was still less than 34% SDI after four years. This is mainly because the 9-year old stand was thinned to 46 residual basal area (RBA), which is 20% SDI while the 8- and 10-year old stands were both thinned to 31% SDI. Since SDI is a computation from BA and TPA, the statistical significance is assumed to be similar.

12.0 ...... Unthinned 8-yr-old \ Thinned 8-yr-old 11.0 \ --...... Unthinned 10-yr-old Thinned 10-yr-old 10.0 ...... Thinned 9-yr-old .. Maximum SDI (100%) 9.0 · - Reduced Response Limit (70%) Upper Growing-Stock Limit (57%) 8.0 Lower Growing-Stock Limit (34%)

7.0 Quadratic Quadratic Mean Diameter (inches) 6.0 ...... 5.0 . 0 200 400 600 800 1000 1200 1400 Trees Per Acre

Figure 8: Quadratic mean diameter (QMD) plotted with corresponding TPA by stand and by thinning treatment for each measurement period. Both the 8- and 10-year-old stands had surpassed the 57% upper growing-stock limit prior to thinning, and after four growing seasons both un-thinned stands are at or slightly below the 70% reduced thinning response limit (Table 9). It is interesting to note that the 8-year old un-thinned stand grew from 60 to 74% SDI while the 10-year old stand only developed from 65 to 69% SDI. This is most likely related to the higher mortality rate in the 10-year-old un-thinned plots. The 10-year old site had less trees per acre and was

expressing a greater site index at thinning compared to the 8-year old stand. The rate of SDI recovery over four growing seasons has been 16%, 13%, and 13% for the 8-, 10-, and 9-year-old thinned stands respectively.

Table 9: Calculated average percent stand density index by stand and treatment type at each measurement period. Before After Stand Treatment Thinning Thinning 2 Years 4 Years 8-year old Thinned 60% 31% 40% 47% 8-year old Un-thinned 60% 60% 67% 74% 10-year old Thinned 66% 31% 38% 44% 10-year old Un-thinned 65% 65% 67% 69% 9-year old Thinned -- 20% 28% 33%

Data Results and Discussion The 8- and 10-year-old plots were thinned at a biologically optimal time based on the increased mortality of the un-thinned plots over four years compared to the thinned plots. This is reflected in the SDI values as both stands were thinned at a point just slightly above the upper growing-stock limit and had not reached the reduced response limit or density-induced mortality limit. It is interesting to note that all three sets of thinned plots had similar BA development rates post-thinning. The 10-year-old un-thinned plots did exhibit greater mortality over four years compared to the 8-year-old un-thinned plots, which may explain the reduced BA growth of the 10-year-old plots since both stands had similar diameter growth over the same period.

COMPARISON OF MEASURED GROWTH TO MODELED GROWTH

Plum Creek’s proprietary growth and yield models are based on a combination of cooperative research data and internal operational studies. These models are incorporated into an internal computer program called the Stand Optimization System, or SOS. It has the capability to run individual plantation regimes from establishment or mid-rotation, as well as a range of scenarios with the regime analysis function.

Modeling the stand growth from the historical establishment records up to the age prior to thinning proved difficult because some of the reforestation records did not include a seedling survival estimate at the end of the first growing season. Also, operational estimates of planted trees per acre as well as seedling survival estimates tend to have a wide coefficient of variance due to small sample sizes. However, comparisons can be made between the actual measurements from this study to modeled data based on trees per acre and basal area as inputs. The model calculates average diameter as a quadratic mean diameter (QMD) and not mean diameter, so QMD was computed for each set of TPA and BA plot measurements. The before and after thinning measured TPA and BA were input into the model, with QMD and average height as outputs to compare to the measured data. In order to reflect site productivity, the base site index can be adjusted within the model in order to match the modeled height closely to the measured height. This provides a similar site index projection for the modeled stand compared to the measured data. Then, the measured data for all plots after thinning was used in the model as a baseline to project growth and yield for two and four years to compare against the measured data at those times. This was an operational comparison, and so no statistical analysis was performed. The objective was to show any large discrepancies between the modeled and measured data, and review those scenarios with Plum Creek’s biometricians.

8-Year-Old Stand – Measured versus Modeled Growth For the thinned plots, the model reduced the trees per acre through mortality though the basal area, diameter and heights were fairly comparable to the measured data (Table 10).

Quadratic mean diameter was similar between measured and modeled, and average height was slightly shorter for the modeled data.

Table 10: Measured and modeled data for the 8-year-old thinned plots before thinning, after thinning, 2 years and 4 years after thinning. Basal area (ft2/acre), QMD (inches), and height (feet). Before Thinning After Thinning 2 Years 4 Years (Age 8) (Age 8) (Age 10) (Age 12) Measured Modeled Measured Modeled Measured Modeled Measured Modeled TPA 656 656 325 325 325 322 325 318 BA 134 135 71 71 96 96 118 115 QMD 6.1 6.1 6.3 6.3 7.4 7.4 8.2 8.2 Height 39.8 39.8 40.8 39.8 50.1 48.5 57.5 55.9

For the un-thinned plots, the model tended to hold more TPA throughout the 4-year measurement period compared to the actual. This resulted in higher modeled BA values, though diameter was similar to the measured data and modeled heights were again slightly less than measured (Table 11).

Table 11: Measured and modeled data for the 8-year-old un-thinned plots at initial measurement, 2 years and 4 years later. Basal area (ft2/acre), QMD (inches), and height (feet). Age 8 2 Years (Age 10) 4 Years (Age 12) Measured Modeled Measured Modeled Measured Modeled TPA 644 644 593 629 569 612 BA 135 136 159 169 180 193 QMD 6.2 6.2 7.0 7.0 7.6 7.6 Height 41.8 41.4 52.1 50.4 59.9 58.1

10-Year-Old Stand – Measured versus Modeled The model tended to hold slightly more trees per acre on the thinned plots, as well as higher basal areas which increased the modeled QMD compared to the measured data. However, the model predicted taller average tree heights than the measured heights 2 and 4 years after thinning (Table 12).

Table 12: Measured and modeled data for the 10-year-old thinned plots before thinning, after thinning, 2 years and 4 years after thinning. Basal area (ft2/acre), QMD (inches), and height (feet). Before Thinning After Thinning 2 Years 4 Years (Age 10) (Age 10) (Age 12) (Age 14) Measured Modeled Measured Modeled Measured Modeled Measured Modeled TPA 613 613 258 258 251 256 249 254 BA 154 155 75 75 96 106 115 129 QMD 6.8 6.8 7.3 7.3 8.4 8.7 9.2 9.7 Height 52.4 52.4 53.5 52.4 60.0 63.1 66.7 71.6

As in the case of the un-thinned 8-year-old plots, the model held more trees per acre over the 2 and 4 year period (Table 13). In this case though, the model also predicted higher diameters compared to the measured diameters which may be reflected in the higher basal areas. As with the thinned plots, the model predicted average heights higher than the measured data which is in contrast to the 8-year-old modeled data.

Table 13: Measured and modeled data for the 10-year-old un-thinned plots at initial measurement, 2 years and 4 years later. Basal area (ft2/acre), QMD (inches), and height (feet). Age 10 2 Years (Age 12) 4 Years (Age 14) Measured Modeled Measured Modeled Measured Modeled TPA 605 605 527 588 489 569 BA 153 154 162 190 174 215 QMD 6.8 6.8 7.5 7.7 8.1 8.3 Height 54.1 53.8 61.6 64.7 68.4 73.3

9-Year-Old Stand – Measured versus Modeled As with the 10-year-old thinned plots, the model predicted larger diameters and higher basal areas versus the measured data (Table 14). Also, the model projected taller average tree heights that were similar over-estimations as the 10-year-old modeled scenarios.

Table 14: Measured and modeled data for the 9-year-old thinned plots after thinning, 2 years and 4 years after thinning. Basal area (ft2/acre), QMD (inches), and height (feet). After Thinning (Age 9) 2 Years (Age 11) 4 Years (Age 13) Measured Modeled Measured Modeled Measured Modeled TPA 216 216 211 215 211 213 BA 46 46 68 72 86 94 QMD 6.2 6.3 7.7 7.8 8.6 9.0 Height 46.0 46.1 52.6 55.6 57.2 63.4

Modeled versus Measured Comparison - Results and Discussion The observed variance between the measured and modeled attributes has a few visible patterns. One of the most notable variations occurred on both the 8- and 10-year-old un- thinned plots. The model overestimated trees per acre on the 8- and 10-year-old un- thinned plots by 6-12% at 2 years and 8-16% by 4 years, respectively. Modeled basal area for these plots was also substantially overestimated by 6-17% for the 8- and 10-year- old in 2 years and by 7-24% at the end of 4 years. The model predicted the same QMD for the 8-year-old un-thinned plots, while slightly overestimating the 10-year-old un- thinned plots by 2-3%. Average height was projected 3% less than measured average height in the 8-year-old plots and 5-7% overestimated in the 10-year-old plots (Table 15).

Table 15: Percent difference between modeled and measured data for trees per acre (TPA), basal area (BA), quadratic mean diameter (QMD), and average height. If percent is positive, model overestimated the value compared to measured data; if percent is negative, model underestimated the value compared to measured data. Un-Thinned Plots Thinned Plots 8-Yr-Old 10-Yr-Old 8-Yr-Old 10-Yr-Old 9-Yr-Old 2 Yrs 4 Yrs 2 Yrs 4 Yrs 2 Yrs 4 Yrs 2 Yrs 4 Yrs 2 Yrs 4 Yrs TPA 6% 8% 12% 16% -1% -2% 2% 2% 2% 1% BA 6% 7% 17% 24% 0% -3% 10% 12% 6% 9% QMD 0% 0% 3% 2% 0% 0% 4% 5% 1% 5% Height -3% -3% 5% 7% -3% -3% 5% 7% 6% 11%

Except for the 8-year-old plots, the model over-predicted on all values for the thinned plots. Modeled TPA was only 1-2% over measured for the 10- and 9-year-old thinned

plots, though BA was 6-12% above the measured values. Modeled QMD values ranged from 1-5% above measured, and average height was 5-11% taller than measured tree heights. Modeled tree height is based on the expressed site index, which is a point in time measurement.

One of the main discrepancies between the measured and the modeled data is the number of trees per acre and basal area. There are several reasons for this variance. First, it does appear as though the model carries more trees per acre, especially in the un-thinned scenarios, which is due to the mortality function that the model uses. The mortality function for the Lower Coastal Plain model is based on a set of data that suggests that mortality decreases as site index increases. Therefore, at 90-100 feet of expressed site index, the model may be extrapolating that decrease in mortality to an extent that is beyond the original data set. Another issue with the current model is that it does not penalize the thinning response if a stand has developed beyond the upper-density limit of 57% SDI. Long-term cooperative data sets of spacing trials show that thinning response is delayed by as much as two years after treatment if SDI gets above 60% (Hogg and Taylor, 2012). The 10-year-old stand was at 65-66% SDI at time of thinning, while the 8-year-old stand was at 60% SDI. Finally, the 8- and 9-year-old stands were fertilized with nitrogen and phosphorous 4 and 3 years prior to thinning, respectively. The 10- year-old stand was fertilized in 2006, six months prior to thinning. The model uses the same fertilizer response for all stands, which in the current model projects additional growth over six years after application. The modeled data for the 10-year-old stand is reflecting most of the fertilizer response, which may or may not be accounted for in the measured data due to nitrogen volatilization, suboptimal weather at time of application, or other factors (Hogg and Taylor, 2012).

It is important to note that the small sample size of this study as well as the relatively short timeframe is prohibitive to making any substantive changes to model functions. However, work has already been completed and is ongoing regarding the above observed variances. These trends have been noted in other internal studies, and an effort to analyze various sources of thinning research is being used to understand how to adjust model

29 functions that are used to predict response and stand development after thinning. A research project has recently been proposed to quantify the thinning response of high productivity stands at various levels of stand development by installing before and after thinning plots in stands with varying site index and SDI values.

OPTIMAL REGIME DEVELOPMENT – FINANCIAL ANALYSIS

With the results of the model comparison in mind, finding an accurate optimal regime in terms of thinning intensity and timing using the current growth and yield models is limited. Because the un-thinned plots resulted in the greatest of variances from modeled to measured data with these study plots, especially the trees per acre estimation, the future stand projections of the un-thinned data are not reliable. Therefore, a financial analysis of the un-thinned data was not performed. However, a general financial analysis with the thinned data is still useful in terms of evaluating the overall value of thinning high productivity stands. In order to minimize model variances, all the measured data will be used and future projections will be modeled from the 4-year data.

Using SOS for growth and yield projections, a regime analysis was conducted to evaluate the financial impacts of thinning these three highly productive stands at various times as well as final harvest ages. The following assumptions and model inputs were used: • Real discount rates (no inflation) of 5%, 10%, and 15%. • No annual taxes or fees. • Reforestation cost of $380 per acre (includes shear, rake, bed, chemical site preparation, herbaceous weed control, seedlings, planting, and phosphorous fertilization). • The N+P fertilization treatments done before thinning cost $100 per acre. • Since all three stands received a fertilization treatment of N+P within 2 years before thinning, no additional fertilizer was applied in order to focus the analysis on thinning response only. • Residual basal area for the second thinning was set at 75 ft2 per acre. Since the model is based on data from lower productivity stands compared to the study sites, varying the basal area target will most likely confound any meaningful results from this analysis. Plum Creek’s first and second thinning target is presently 75 BA based on research conducted by the PMRC. • If a thinning generated less than 20 tons per acre, it was considered not practical.

• Volume from early thinning (less than 12 years of age) was applied as 100% pulpwood in terms of product allocation. • Stumpage pricing was applied in three ranges, with “Low” reflecting the current pricing in the southeastern US for southern yellow pine. Moving from “Low” to “High”, pulpwood increases by $5 per ton, chip-n-saw (CNS) increased by $10 per ton, and saw timber increases by $15 per ton (Table 16). This way, the differential between fiber and solid wood increases as the pricing increases. For each financial analysis, the assigned stumpage pricing was held constant throughout the rotation. In other words, no price appreciation or inflation was employed.

Table 16: Range of stumpage pricing used in the financial analysis. Values are in $/ton. Low Moderate High Pulpwood, 5”+ DBH $10 $15 $20 Chip-n-Saw (CNS), 8-13” DBH $15 $25 $35 Saw timber, 14”+ DBH $25 $40 $55

For the financial analysis, Net Present Value (NPV) was calculated for each scenario using the following formula:

= (1 + ) (1 + ) 푅푒푣푒푛푢푒푠 퐶표푠푡푠 푁푃푉 � � 푛 � − � � 푛� 푖 푖 Revenues = Sum of positive cash flows generated through harvests, individually discounted to year 0. Costs = Sum of negative cash flows or investments, individually discounted to year 0. i = Discount or interest rate n = Year in which cash flow occurs

Bare Land Value (BLV) was calculated using the following formula: (1 + ) = (1 + ) 1푡 푁푃푉 푖 퐵퐿푉 � 푡 � 푖 − NPV = Net Present Value i = Discount or interest rate t = Rotation length

The financial analysis was conducted by first generating growth and yield data for each of the averaged plots by using the measured data and then modeling the stand from the 4- year data without any additional thinning. The rotation age is an output of the analysis and was selected based on the maximum BLV for each scenario.

In order to analyze a two-thin regime, a thinning trigger for the second thin must be selected. In the case of a the first thin, using SDI as a trigger provides better results from a biological, stand development point. However, if the objective of the second thinning is more financially driven then a trigger of diameter or basal area growth is more appropriate. In Plum Creek’s current harvest scheduling process, the residual basal area of the second thin is set to 75 ft2/acre and then the model runs several timing scenarios on an existing stand inventory to select the one with the highest financial return. Using this approach to determine the timing of the second thin, several timing scenarios were run using SOS by assuming a 75 residual BA. A financial analysis was then conducted for each set of growth and yield tables by calculating NPV and BLV, with the rotation age decided by the maximum BLV.

8-Year-Old Stand – Financial Analysis Using the measured data through age 12, the 8-year-old thinned plots were modeled to age 30 with no second thin as well as second thin at ages 12, 14, 16, and 18. At 5% discount rate and regardless of stumpage pricing, the most financially optimal regime includes a second thinning at age 16 with a final harvest at age 24. A second thin at age 14 with a final harvest age of 20 is the best solution at a 10% discount rate. When the

33 discount rate is set at 15%, the best financial regime included a thin at age 12 and a final harvest at age 16 (Table 17).

Table 17: Financial analysis of the 8-year-old thinned plots, with values expressed as BLV ($/acre) with the rotation age in years in parenthesis. Stumpage pricing refers to price per ton ranges set forth in the assumptions. 5% Discount Rate 10% Discount Rate 15% Discount Rate Stumpage Low Mod High Low Mod High Low Mod High Pricing No Second $962 $1921 $2881 $124 $513 $901 -$136 $66 $267 Thin (20) (20) (20) (16) (16) (16) (14) (14) (14) Second $1185 $2254 $3322 $189 $604 $1018 -$110 $98 $306 Thin at 12 (22) (22) (22) (18) (18) (18) (16) (16) (16) Second $1245 $2340 $3436 $199 $612 $1024 -$116 $82 $284 Thin at 14 (24) (24) (24) (20) (20) (20) (18) (18) (16) Second $1266 $2376 $3487 $186 $590 $995 -$132 $56 $244 Thin at 16 (24) (24) (24) (22) (20) (20) (20) (18) (18) Second $1260 $2360 $3461 $157 $539 $921 -$156 $14 $185 Thin at 18 (26) (26) (26) (22) (22) (22) (20) (20) (20)

Rotation age is an output decided by financial returns. It is interesting to note that stumpage pricing did not impact rotation age nearly as much as the discount rate. Also note that at 15% with moderate and high stumpage pricing, the second thin at ages 16 and 18 resulted in lower revenues compared to not conducting the second thin at all. The time value of money at this rate tended to trump the additional solid wood volume generated by a later second thinning.

10-Year-Old Stand – Financial Analysis Using the measured data through age 14, the 10-year-old thinned plots were modeled through age 30 with no second thin as well as a second thin at ages 14, 16, 18, 20, and 22. At a 5% discount rate, the most optimal second thin timing was age 18 with a final harvest at 26 for the low stumpage pricing and 24 for the moderate and high pricing. Increasing the discount rate to 10% shifted the optimal second thin timing to age 14 with a final harvest at age 20 for the low and moderation pricing and 18 with the high

34 stumpage rates. The second thin timing stayed at age 14 when the discount was raised to 15%, but the final harvest age decreased to 18 at the low stumpage rates and age 16 for the moderate and high rates (Table 18).

Table 18: Financial analysis of the 10-year-old thinned plots, with values expressed as BLV ($/acre) with the rotation age in years in parenthesis. Stumpage pricing refers to price per ton ranges set forth in the assumptions. 5% Discount Rate 10% Discount Rate 15% Discount Rate Stumpage Low Mod High Low Mod High Low Mod High Pricing No Second $1320 $2457 $3594 $243 $675 $1107 -$87 $121 $329 Thin (22) (22) (22) (18) (18) (18) (16) (16) (16) Second $1488 $2703 $3923 $314 $775 $1241 -$54 $167 $392 Thin at 14 (24) (24) (22) (20) (20) (18) (18) (16) (16) Second $1500 $2726 $3951 $294 $746 $1198 -$73 $137 $346 Thin at 16 (24) (24) (24) (20) (20) (20) (18) (18) (18) Second $1531 $2775 $4020 $287 $727 $1167 -$85 $112 $310 Thin at 18 (26) (24) (24) (22) (22) (22) (20) (20) (20) Second $1529 $2766 $4004 $255 $674 $1094 -$108 $72 $252 Thin at 20 (26) (26) (26) (24) (22) (22) (22) (22) (22) Second $1492 $2699 $3906 $217 $609 $1001 -$132 $30 $191 Thin at 22 (28) (28) (28) (24) (24) (24) (24) (24) (24)

As with the 8-year-old financial analysis, rotation age was impacted more directly by the discount rate rather than the stumpage rate. Also note that at 15%, a second thin at age 18, 20, or 22 resulted in a BLV less than the BLV of no second thin regardless of stumpage pricing.

9-Year-Old Stand – Financial Analysis Using the measured data through age 13, the 9-year-old thinned plots were modeled through age 33 with no second thin as well as a second thin at ages 13, 15, 17, 19, 21, and 23. The second thin conducted at age 13 only yielded 14 tons per acre, which is not operational as set forth in the assumptions. Since the 9-year-old plots were more heavily thinned in terms of residual BA and SDI, the financial analysis at 5% tended to favor

waiting a longer period of time before conducting the second thin at age 21 with a final harvest at age 27. With the discount rate at 10%, there were no scenarios that resulted in a positive BLV at the low stumpage rates. The optimal second thin age became 17 with a final harvest at age 21 at the moderate and high stumpage pricing. At a 15% discount rate, there were no scenarios at any stumpage range that yielded positive financial results (Table 19).

Table 19: Financial analysis of the 9-year-old thinned plots, with values expressed as BLV ($/acre) with the rotation age in years in parenthesis. Stumpage pricing refers to price per ton ranges set forth in the assumptions. 5% Discount Rate 10% Discount Rate 15% Discount Rate Stumpage Low Mod High Low Mod High Low Mod High Pricing No Second $547 $1255 $1963 -$125 $107 $339 -$291 -$191 -$91 Thin (23) (23) (23) (19) (19) (19) (17) (17) (17) Second $646 $1397 $2147 -$88 $156 $401 -$277 -$175 -$70 Thin at 15 (25) (25) (25) (21) (21) (21) (19) (19) (17) Second $678 $1444 $2212 -$86 $159 $405 -$281 -$183 -$84 Thin at 17 (27) (25) (25) (21) (21) (21) (21) (19) (19) Second $703 $1480 $2260 -$92 $144 $379 -$289 -$199 -$110 Thin at 19 (27) (27) (25) (23) (23) (23) (21) (21) (21) Second $704 $1482 $2261 -$110 $111 $334 -$303 -$225 -$147 Thin at 21 (27) (27) (27) (25) (23) (23) (23) (23) (23) Second $686 $1445 $2205 -$133 $71 $276 -$318 -$252 -$186 Thin at 23 (29) (29) (29) (25) (25) (25) (25) (25) (25)

As with the 8- and 10-year-old financial analyses, rotation age was impacted more directly by the discount rate rather than the stumpage rate. The 9-year-old plots were first-thinned to 26 tons of residual volume (20% SDI), while the 8- and 10-year-old thinned plots were thinned to 35 and 51 tons respectively. The lack of tons to grow throughout the rest of the rotation limited the financial performance of the 9-year-old plots, especially at the 10% and 15% discount rates. However, at 15% interest it is still better financially in terms of losing the least dollars to second-thin at age 15.

Financial Analysis - Results and Discussion The discount rate affected the timing of the second thin and rotation age more than the stumpage pricing. It also appeared as though the impact to BLV from 5% to 10% discount rate was greater proportionally compared to the change in BLV from 10% to 15%. For example, the BLV of the 9-year-old stand with a second thin at age 21 ranged from $2261 to $704 at the high and low stumpage pricing which is a 69% decrease. At the high stumpage pricing, the BLV decreased by 82% when the discount rate increased from 5% to 10%, or $2261 to $405. Then at the 15% discount rate, the BLV decreased to -$70.

The variance in BLV across the stumpage pricing ranges was in general the widest at 5% interest rate compared to 10 and 15%. Using the same example scenario as above, the BLV ranged from $704 to $2261 at the 5% interest rate which is a difference of $1557. At 10%, the BLV ranged from -$110 to $334 which is a difference of $444. The difference between the low and high stumpage pricing at 15% interest is $156. This is due to time value of money, which is especially notable in forestry because time periods are measured in years and decades.

In all three sets of thinned plots, it was better financially to conduct the second thinning compared to the one-thin regime regardless of low stumpage pricing or a high discount rate. Even given the modeled difference compared to the measured data outlined in the previous discussion, the financial analysis performed here is representative of typical two-thin scenarios currently being scheduled. Further study is needed though in order to fine tune how the thinning response is applied in the model across ranges of site productivity and stand development.

CONCLUSIONS

The first-thin is most effective at increasing the production of higher value solid wood products and minimizing tree mortality when it is conducted soon after crown closure when tree crowns are still vigorous, and crown ratios are 40% or more on average (Harrington 2000). The timing of the first-thin relies more on biological stand development, and so using stand density index as a trigger for the timing of the first-thin appears to be effective in terms of managing density to minimize volume losses to mortality. In order to maintain productivity, the stand should be thinned at the upper- growing stock limit of 57% SDI to the lower growing stock-limit of 34% SDI. This corresponds generally to 70 to 80 BA as a residual target.

Even though the study sites were thinned at earlier ages than traditionally practiced in the southeastern US, the 8- and 10-year old stands were slightly above the 57% SDI at the time of thinning. Within 4 years, both un-thinned sites were at or above 70% SDI and experiencied higher mortality rates which indicates that the first thin timing was appropriate for these stands. With respect to thinning intensity, 70-75 residual BA provided better financial returns as shown in the 8- and 10-year-old sites compared to thinning the 9-year old stand to 46 residual BA. This study along with the modeled data supports using SDI as a first-thin trigger, although the results do suggest that further research needs to be done in order to more accurately model stands with high site index values at various stages of stand development.

High growth rates coupled with the current low solid-wood stumpage pricing did not preclude the second-thin in terms of financial returns for any of the three stands. Even at the low stumpage pricing, which has the least differential between fiber and solid wood products, it was financially superior to conduct the second thinning. The discount rate appeared to affect the timing of the second-thin as well as the final harvest age more so than the stumpage pricing.

The timing of the second thin is currently calculated using financial return as a trigger. However, what to use as a second-thin trigger is still of debate. Basal area does incorporate diameter, which is directly correlated to the percent solid wood that can be merchandized as well as financial returns. Some biometricians have speculated about using QMD as a thinning trigger which accounts for BA and TPA. In terms of SDI, thinned stands generally do not return to the upper-growing stock limit for ten years or more. This is function of having to make up the value mainly in BA growth considering that the TPA was reduced in the first thinning. This is also the reason that live crown ratio is not generally considered at this point in the rotation, mainly because the trees have ample room for crown development if the first thin was conducted properly. There currently is very little in terms of second thinning research results available, and residual stand goals of the existing research generally vary from TPA to BA. Further research is needed to understand the response to a second thin on plantations of varying densities, diameters, and ages, in order to quantify the magnitude of the thinning response.

It is difficult to recommend specific changes to Plum Creek’s growth and yield models based solely on this set of study data because of the low sample size as well as the relatively short timeframe of measured stand development. However some of the trends evident in this data set have been noted in other research studies, particularly the mortality of un-thinned plantations with high site index values. There is definitely a need for more research focused on thinning responses in relation to site index and stand development, for both first and second thins. Currently, the FPC and thePMRC have ongoing studies that are designed to evaluate thinning responses of more intensively managed plantations though the data is still relatively short termed. This data coupled with internal research will provide the next link to improving the validity of growth and yield modeling in regard to thinning response. In the meantime, SDI has been added to the harvest schedule as a first-thin trigger to help foresters target these operations more effectively. Finally, the financial returns of a second thin in plantations with higher than traditional site index values are still viable even at the current low stumpage pricing. The traditional two-thin regime continues to be a viable approach to loblolly pine plantation management in the southeastern US.

LITERATURE CITED

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APPENDICES

Appendix A. Summary of the thinning study in the 8-year-old stand over four growing seasons after thinning. Merchantable volume is volume of trees 4” DBH or larger to a 3” top diameter. Probability of a greater F-Value (Prob. >F) tests that there is no significant difference (Diff) between thinned and unthinned stands.

Aug 2006 Feb Sept Total Total Total + Initial Removal Remaining 2009 2010 Mortality Growth Removals Trees per acre Thinned 656 331 325 325 325 0 Unthinned 644 0 644 593 569 76 Diff 16 -319 -268 -244 -76 Prob.>F 0.115 0.005 0.004 0.004 0.042 Basal Area (ft2 ac-1) Thinned 134 63 71 96 118 47 181 Unthinned 135 0 135 159 180 45 180 Diff -1 -64 -63 -62 2 1 Prob.>F 0.467 0.002 0.003 0.005 0.660 0.720 Total Volume (ft3 ac-1) Thinned 2441 1121 1320 2230 3222 1902 4344 Unthinned 2589 0 2589 3895 5181 2593 5181 Diff -148 -1269 -1665 -1959 -691 -837 Prob.>F 0.004 0.004 0.004 0.029 0.006

Merchantable Volume (ft3 ac-1)

Thinned 2234 1008 1226 2144 3139 1912 4146 Unthinned 2399 0 2399 3719 5014 2615 5014 Diff -165 -1173 -1575 -1875 -703 -868 Prob.>F 0.086 0.005 0.004 0.005 0.030 0.008 DBH (in) Thinned 6.0 6.2 7.2 7.9 1.74 Unthinned 6.1 6.1 6.9 7.4 1.37 Diff -0.1 0.1 0.3 0.5 0.37 Prob.>F 0.013 0.256 0.075 0.049 0.090 Total Height (ft) Thinned 39.8 40.8 50.1 57.5 16.7 Unthinned 41.8 41.8 52.1 59.9 18.0 Diff -2.0 -1.0 -2.0 -2.0 -1.3 Prob.>F 0.097 0.352 0.118 0.154 0.177

Appendix B. Summary of the thinning study in the 10-year-old stand over four growing seasons after thinning. Merchantable volume is volume of trees 4” DBH or larger to a 3” top diameter. Probability of a greater F-Value (Prob. >F) tests that there is no significant difference (Diff) between thinned and unthinned stands.

Jul 2006 Feb Sept Total Total Total + Initial Removal Remaining 2009 2010 Mortality Growth Removals Trees per acre Thinned 613 355 258 251 249 9 Unthinned 605 0 605 527 489 116 Diff 8 -347 -276 -240 -107 Prob.>F 0.638 0.001 0.001 0.001 0.001 Basal Area (ft2 ac-1) Thinned 154 79 75 96 115 40 194 Unthinned 153 0 153 162 174 21 174 Diff 1 -78 -66 -59 19 20 Prob.>F 0.688 0.001 0.012 0.021 0.087 0.079 Total Volume (ft3 ac-1) Thinned 3812 1958 1854 2670 3585 1731 5542 Unthinned 3937 0 3937 4786 5763 1826 5763 Diff -125 -2083 -2116 -2178 -95 -221 Prob.>F 0.437 0.006 0.016 0.027 0.737 0.396 Merchantable Volume (ft3 ac-1) Thinned 3620 1832 1788 2612 3530 1742 5362 Unthinned 3747 0 3747 4630 5619 1872 5619 Diff -127 -1959 -2018 -2089 -130 -257 Prob.>F 0.459 0.006 0.017 0.029 0.658 0.325 DBH (in) Thinned 6.7 7.2 8.3 9.1 1.85 Unthinned 6.6 6.7 7.4 7.9 1.23 Diff 0.1 0.5 0.9 1.2 0.62 Prob.>F 0.735 0.014 0.042 0.035 0.063 Total Height (ft) Thinned 52.4 53.5 60.0 66.7 13.1 Unthinned 54.1 54.1 61.6 68.4 14.3 Diff -1.7 -0.6 -1.6 -1.7 -1.2 Prob.>F 0.421 0.740 0.378 0.364 0.463

Appendix C. Summary of the thinning study in the 9-year-old stand over four growing seasons after thinning (only thinned stand data was available). Merchantable volume is volume of trees 4” DBH or larger to a 3” top diameter. Probability of a greater F-Value (Prob. >F) tests that there is no significant difference (Diff) between thinned and unthinned stands.

Aug 2006 Feb Sept Total Total Total + Initial Removal Remaining 2009 2010 Mortality Growth Removals Trees per acre Thinned 216 211 211 5

Basal Area (ft2 ac-1) Thinned 46 68 86 40

Total Volume (ft3 ac-1) Thinned 977 1645 2307 1329

Merchantable Volume (ft3 ac-1) Thinned 915 1597 2262 1347

DBH (in) Thinned 6.2 7.6 8.4 2.2

Total Height (ft) Thinned 46.0 52.6 57.2 11.2

V L 1,506 3,028 3,282 3,436 3,468 2,429 3,487 2,024 2,693 B $ $ $2,693 $ $ $ $ $ $ S 1 933 ,300 ,614 ,847 ,847 1 1 1 1 2,384 2,56 2,706 2,662 2J39 NPV $ $ $ $ $ $ $ $ $ $ ) ) High l 5 (7 00 380 387 860 , ( esent 1,368 1,915 1,055 1,769 1,870 1,915 1,682 1 r Value P $ $ $ $ $ $ $ $ $ $ $ $ $1,347 $1,592 ) ) h 00 705 631 571 876 380 224 ,277 ,179 , ow (1 ( l 1, 1, 1 2,303 3,330 3,242 6,031 6,808 5,175 4 2,457 Cas F $ $ $ $ $ $ $ $ $ $ $ $ $ $ $4 $ 6 914 1,292 1,585 1,778 1)78 2,217 2)67 2,026 2,334 2,37 BLV $ $ $ $ $ $ $ $ $ S 0 9 9 4 0 1 1 1 1 4 566 830 U e 1,6 1,8 1,053 1,847 1,432 1} t NPV $ $ $ $ $ $ $1,2 $ $ $ ) 1 1 1 5 (7 Modera 73 76 623 994 973 380) 290 ( esent l,152 1,28 1,218 1,384 1,356 r Value P $ $ $ $ $ $ $ $ $ $ $ $ $1,389 $ ) 00) 1 380 958 938 529 429 , ow ( ( l 1)90 1,661 3,021 3,056 3,748 2,411 2,342 Cash F $ $ $ $ $ $1,786 $1,360 $4,372 $4 $ $ $ $ $ $ $ 1 66 V 741 32 559 863 863 ) L ,233 ,266 1 1 1 B $ $ $ $ $ $1,151 $1,025 $ $ $ 199 724 359 919 988 592 592 836 966 492 NPV $ $ $ $ $ $ $ $ $ $ ) ) t Low 1 5 (7 193 754 711 794 386 620 599 84 853 863 380 460 467 ( esen old thinned plots with a second thin at age 16 and final harvest at age 24 for the age at 24 for final low, old 16 and harvest thin age thinned plotsat second with a r - Value $ $ $ $ $ $ $ $ $ $ $ $ $ $ P ) ) year h 00 - 749 843 888 020 380 353 638 442 286 ow ,863 ,492 (1 ( l 1, 1, 1, 1 1 Cas F $ $ $ $2,322 $2,713 $3,068 $ $ $ $ $ $ $ $Ul4 $ $ al 67 t 1. To 28.57 71.38 63.84 35.27 64.21 6 88.91 88.52 113.16 107.26 139.42 153.23 124.11 135.59 ) 7 00 00 00 00 00 4 . . . . . ons t 1. 1.03 0 0 0 0 0 5.33 Saw 4.30 ( 19.55 71.32 36.57 86.39 1 1 5.78 8.3 0.00 0.00 0.00 CNS 67.7 37.08 51.98 53.27 51.28 54.96 85.39 49.74 47.99 4 26.50 Volume 7 0 4 4 1 77 87 87 85 27 .1 ...... Financial analysis of the 8 7.38 7.42 7 8.36 8 8 Pulp

1 1 1 1 1 1 26 35 35 63.84 42.7 43.98 44 28.57 0 6 6 6 8 4 0 6 8 8 8 12 1 1 1 1 1 1 22 26 20 24 Year Appendix D. high stumpage and 5% at pricing interest.moderate, After After Fert Before Before Estab. Thin2 Thinl 50

V 808 893 893 856 976 987 928 636 ,024 ,022 L 1 1 B $ $ $ $ $ $ $ $ $ S 59 707 707 789 613 801 866 879 892 842 4 NPV $ $ $ $ $ $ $ $ $ $ ) High 0) 4 nt e 56 ( 783 709 353 629 618 683 696 659 607 52 877 267 (38 alu ese r V P $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) h 705 380 571 800 , ow (100) ( l 1,631 1,991 1,277 7,229 6,496 5,665 3,330 4,769 Cas F $ S $ $ $ $ $ $ $ $ $2,457 $1,340 $2,842 $3 $ $ 2 1 98 48 308 606 503 503 568 588 5 6 438 4 BLV $ $ $ $ $ $ $ $ $ S - 4 4 98 66 60 2-2-2 398 398 332 51 533 52 4 4 4 e :N"PV at $ $ $ $ $ $ $ $ $ $ er d ) 6 4 4 nt e 56 59 9 ( Mo 256 379 635 569 513 50 44 478 440 4 4 200 (380) alu ese r V P $ $ $ $ $ $ S $ $ $ $ $ $ $ cond thin at age 14 and final harvest at age 20 for the age at 20 for final 14 and harvest thin age cond at ) ) 0 h 50 29 958 973 529 4 ow ,4 (380 (10 l 1,190 1,438 2,745 3 2,051 Cas F $ $2,411 $4,102 $4)07 S $ $ $ $ $ $ $ $1,786 $5,241 $ $ 68 99 (20) 141 113 113 159 190 189 169 1 BLV $ $ $ $ $ $ $ $ $ S ) 1 1 0 4 1 90 90 73 69 6 53 52 ( 13 13 1 1 1 1 NPV $ $ S $ $ $ $ $ $ $ ) ) 4 Low nt e 56 ( 133 160 355 393 30 317 312 289 233 274 296 273 old thinned plots se with a alu ese (380 - r V $ $ $ $ $ $ $ $ $ $ $ $ $ $ P ) 9 year 4 - 1 1 h 00 60 131 1 749 885 353 691 638 607 286 ,2 ,492 , , ow (380) ( l 1,1 1 1 1 2,9 2 3,254 2,539 Cas F $ $ $ $ S $ $ $ $ $ $ $ $ $ $ $ 4 66 92 . tal .27 .24 . To 35 65 63.8 61.67 88.52 83.86 47 28.57 165 121.31 113.16 103.29 152.47 137.72 ) 1 0 s n 00 00 00 00 00 .4 24 ...... o t 1.47 1.23 0 0 0 0 0 0 Saw ( 10.0 73.53 57 87.53 41.08 23.90 e 6 00 00 .83 hn:n . . 5.78 4.27 0.00 0 0 CNS 67.71 60.31 60.08 56 59.83 58.18 5 42.8 4 26.50 24.85 Vo 4 76 98 . 9.58 9.56 9.92 Pulp 1 1 1 20 22.83 63.8 35.27 35.17 42.74 43. 28.57 21.15 20.24 21.30 ar 4 4 4 0 6 8 8 8 18 10 16 12 1 1 1 20 22 24 26 Ye e e . r l b er a for t Appendix E. Financial analysis of the 8 the of analysis Appendix Financial E. pricing high and 10% at interest. stumpage low, moderate, ert Thin2 Thin Aft After Befo Be Es F 51

6 154 110 264 200 303 30 208 264 282 246 BLV $ $ $ $ $ $ $ $ $ S 1 1 192- 167 149 107 223 277 223 265 26 23 NPV $ $ $ $ $ $ $ $ $ $ gh ) t Hi 1 1 3 8 2 e 1 0 87 4 (4 1 1 287 244 36 372 356 327 3 403 459 2 (380) alu esen r V P $ $ $ $ $ $ $ $ $ S $ $ $ $ 1 1 h 71 00) 1 705 754 5 ,993 ow , {380) { l 1,63 1,703 7,666 6).14 6 5,35 Cas F $ $ $ $ $ $ $ $ $1,277 $2,457 $2554 $3,485 $4,407 $ $ $ 3) 4 ( 1 92 60 60 60 83 98 29 (34) BLV $ $ $ $ $ $ $ $ $ s 1 3) ( 11 77 51 56 5 80 89 28 (34) e t NPV $ $ $ $ $ $ $ s $ $ era d t e 43) ( Mo 103 177 147 140 231 257 334 294 261 269 237 208 {380) alu esen r V P $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) 4 h 86 90 958 380) 529 550 845 429 ,235 ,065 , ow (100 ( l 1,1 1 1 1} 3,871 2,517 Cas F $ $ $ $ $ $ $ $ $ $ $3,18 $4,498 $5 $5,555 $ $ 0) 61) 44) 1 1 11 ( (180) (144) (119) (115) (126) (143) (179) ( { BLV $ $ $ $ $ $ $ $ $ S ) ) ) ) 6 2 19) 06 05) 74) 55) 45) V (99) 13 12 1 1 1 1 1 1 P (122 ( ( ( ( ( ( ( { N : $ $ $ $ $ $ S $ $ $ ) t e Low 10 93 91 65 {43 185 143 166 159 146 129 160 1 208 alu (380) esen r V $ $ $ $ $ $ $ $ $ $ $ $ $ $ old thinned plots with a second thin at age 12 and final harvest at age 16 for the age at 16 for final low, old 12 and harvest thin age thinned plotsat second with a P - 8 4 1 3 h 749 767 6 286 353 347 year (380) (100) ow - 1,1 l 1,136 1,549 1,962 3,138 3,444 2,391 2,783 Cas F $ $ $ $ $ $ $ $ S $ $ $ $ $ $ $ 8 4 66 .1 .1 . tal .55 9.40 To 28.57 79.30 35.27 61.67 63.84 59.97 88.52 28 11 168 137 180 100.10 153.42 1 1 s) n o 0.06 t 0.00 0.00 0.00 0.00 0.06 5.96 Saw ( - 16.17 73.8 60.1 86.04 44.97 28.58 e 79 50 88 88 05 62 00 ...... hnn . 0.00 0.00 0 0.00 CNS 12 26 33.73 67 68 69 69.41 61.14 69.42 50 Vo 4 .5 Pulp 16.44 63.84 28.57 26.30 23.89 35.27 35.17 42.74 45.78 22.72 22.79 22.94 23.33 25.21 24 0 6 8 8 8 10 18 14 12 12 12 16 20 22 24 26 Year . e e derate, and high stumpage and 15% at pricing interest. derate, r r l b a t Appendix F. Financial 8 the of analysis Appendix Financial F. mo After After Fert Befo Befo Es Thin2 Thin 52

1 9 6 5 0 17 1 08 0 7 5 44 2 V 1 742 0 9 ,6 ,4 ,0 ,408 , , L 2, 2 3, 3,9 3 3 3 3 4,0 4 B $ $ $ $ $ $ $ $ $ S 8 09 0 82 40 V 717 939 1,3 1,7 2,1 2, 3,121 3,069 3,127 2,4 2,408 2, NP $ $ $ $ $ $ $ $ $ $ gh ) Hi 1) 0 7 9 6 5 5 8 4 nt e 1 6 5 8 48 44 e ( 63 990 9 93 9 s (3 alu e U35 U8 1, 1, 1, 1,5 1,7 1,886 1,22 2,21 r V P $ $ $ $ $ $ $ $ $ $ S S $ $ ) ) 0 3 3 9 6 8 4 h 12 00 72 65 6 8 8 4 w 13 13 1 033 0 9 3 ,0 ,599 o ( ( l 1, 1,032 7 5,332 2, 2,3 3, 6,9 5, Cas F $4,18 $4 $6,082 $ $ $ $ $ $ $ $ $2,0 $2, $ $ $ 7 5 8 2 2 15 35 69 0 9 V 31 31 ,066 ,561 ,77 1,7 2 2, 2,7 2 2 2} BL $ $ $ $ $2, $ $2,7 $1,3 $ S

1 7 7 3 18 60 9 53 6 5 2 V 0 8 8 ,1 ,633 ,633 , e 1,1 1,417 1 1 1 2, t NP $ $ $2 $2,1 $ $ $ $ $ $2,1 era d ) ) t 1 5 5 9 4 lo n e 12 1 74 61 08 v e ( I 11 11 7 2 380 88 863 47 ,4 ,4 ,369 , , , ( alu es 1,383 1,599 1 1 1 1 1 1 r V P $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) 0) 0 9 9 9 9 0 6 5 5 h 14 1 48 4 4 28 2 w 77 774 721 5 01 38 0 9 ,5 ,55 , , o ,72 , (100 ( .,1 l 1 1 1 3,8 5, 3 3 5 4,4 Cas F $ $ $ $ $ $2, $ $ $ $ $ $2,21 $2 $ $ $ 2 9 6 6 5 8 1 50 9 3 2 4 058 5 6 8 LV , ,5 l B $1 $1, $1,381 $1,4 $ $ $1,21 $1,21 $1,48 S 7 6 4 06 6 95 V 19 1 72 565 859 859 412 ,003 , , P 1,1 1,1 1 1 1 N $ $ $ $ $ $ $ $ $ $ w ) ) 1 1 7 7 7 8 3 4 0 nt Lo 1 7 61 9 4 e ( 98 380 68 690 7 3 53 5 85 850 879 8 44 s ( alue old thinned plots with a second thin at age 18 and final harvest at at 26 for final old the 18 and harvest age thin age thinned plotsat second with a r e - V $ $ $ $ $ $ $ $ $ $ $ $ $ $ P ) ) 1 0 7 6 6 4 6 year 13 1 1 00 08 65 8 - h 033 96 059 36 3 3 5 5 855 824 w ,44 , (1 ( o 1, 1, 1, 1,3 1,3 1 3,126 3 2, 2, 2}4 l Cas F $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ 9 6 6 7 3 2 4 66 8 2 66 6 6 .4 .99 .53 . . tal .5 7.30 8 1. 1. 5.53 8 0. 53 59.35 00 03. 4 To 72.8 7 5 5 132 12 116 1 1 1 1 1 0 5 8 5 9 s) 0 0 6 .12 68 w 4 n 00 77 65 0 0 .8 .41 .41 . 00 ...... o 1. 3.5 6 t 13 Sa 0 0 0 6 9 2.1 ( 1 63 99 82 4 2 1 e 0 0 7 9 5 S 09 68 7 2 hnn 00 00 00 .1 .4 .59 . . . . N . . o 1 3.33 9 6 4 0. 0 C 95.95 39 32 30 35.42 6 84.72 4 4 4 4 V 6 0 2 3 9 6 4 2 13 91 64 0 6 .1 .7 .04 .76 .44 .04 . . . 1. 1. 4.24 4 4 4 4 4 03. Pulp 19 13 15 16 1 1 33.8 3 1 2 0 0 0 5 0 5 6 3 8 8 3 8 8 1 4 0 14 1 1 1 1 1 1 1 1 1 20 22 26 2 2 Year e e . r r ab t Appendix G. Financial analysis of the 10 the of analysis Appendix Financial G. interest. 5% at the pricing pricing high stumpage 24 for and andmoderate low stumpage age Fert Thin2 Thinl After After Befo Befo Es 53

1 0 1 4 2 36 0 9 24 V 01 993 993 9 87 ,24 U 1, 1,178 1)- 1 BL $ $ $ $ $ $ $ $ $1,1 S 1 9 6 6 6 4 78 7 6 4 V 78 78 660 8 935 9 ,0 ,0 ,052 ,00 1 1 1 1 NP $ $ $ $ $ $ $ $ $ $ gh ) ) Hi 1 1 t 7 0 9 3 3 6 8 4 n e 1 1 98 0 7 3 86 24 (3 789 68 60 7 7 7 3 6 5 8 8 28 (38 ah:i ese r V P $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) 5 5 3 0 9 4 1 71 7 36 00 32 3 80) 0 w I 06 065 989 0 0 0 0 669 3 ,4 ,288 ,47 ,389 , , o ( ( l 1, 1, 1, 1, 7,2 3 3 6 5 8, 8 2) 2-, 4 Cash F $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ 5 5 5 8 93 33 36 84 8 8 22 774 77 7 7 55 6 6 5 5 4 LV B $ $ $ $ $ $ $ $ $ S 3 2 74 7 21 22 63 63 V 5 5 60 656 675 655 3 6 4 4 e NP at $ $ $ $ $ $ $ S $ $ er ) ) d 1 t o 0 0 3 5 8 4 n e 17 99 39 36 7 7 7 9 88 8 8 ( M 2 3 3 536 590 5 5 5 5 4 4 4 20 ( alu ese r V P $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) ) 0 0 9 9 5 5 5 5 5 4 h 00 36 7 8 4 4 w 77 77 774 3 820 966 27 ,3 ,6 , (1 o ( l U 1,550 1,4 6,2-9 5, 5, 2 3 2-,21 Cas F $ $ $ $ $ $ $ $ $4 $3,17 $ $ $ $ $ $ 7 5 5 2 4 9 4 V 77 77 1 65 9 9 2 11 1 1 1 2 2 2 30 3 L 27 B $ $ $ $ $ $ $ $ $ S 1 1 1 1 0 9 6 1 6 6 88 V 14 17 140 22 273 24 2 2 2 NP $ $ $ $ $ $ $ $ $ $ w ) ) o t 0 7 4 4 e L 18 99 39 32 ( 127 1 30 360 353 365 35 333 30 3 2 272- old thinned plots with a second thin at age 14 and final harvest at at 20 for final old the 14 and harvest age thin age thinned plotsat second with a (38 alu esen - r V $ $ $ $ $ $ $ $ $ $ P $ $ $ $ ) ) year 0 3 6 6 4 2 - 18 1 1 00 57 8 33 65 63 h 20 w I 5 5 880 96 0 3 9 882 48 ,4 )-78 ,4 ,96 , , , ( ( o l 1,3 1 1 1 2 3,6 3 3 2 Cas F $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ 1 7 9 6 6 1 2 4 99 62 6 25 2 7 53 6 6 .7 . . . . 28 tal .84 . . . 6 5 2.2 1. 1. 9 5 4 10 00 03. 6 To 36 6 5 8 I 17 130 14 187.4 1 1 1 1 ) 1 s 0 7 0 5 0 55 0 6 00 . n w 0 0 .13 . .00 .74 . . 0.13 to 4 1.42 0.0 0 0 0 Sa 2.1 ( 77.1 9 39 2 108 121. e 1 0 0 5 8 0 S 08 0 5 hnn 00 .72- .59 . N o 1.01 5 4. 2.4 0.0 0.00 0 C 52.62 59.45 5 5 21. 64 41.7 43. 48.74 47.08 4 V 6 7 3 8 8 6 5 4 4 4 2 2 96 6 6 6 .1 .28 .04 . 1. 1. 7.5 7.2 8.6 8 9.39 0 0 9 4.2 4. 03. Pulp 1 1 1 1 1 1 1 2 33.8 3 2 1 8 0 0 0 5 0 5 6 4 4 4 0 12 1 1 1 1 1 1 1 1 1 26 28 22 20 24 Year . e e r r ! b a Appendix H. Financial analysis of the 10 the of analysis Appendix Financial H. stumpage 18 and stumpage pricing 10%age at moderate for pricing high low and interest. the st Fert Thin Thin2 After After Befo Befo E

0 9 6 8 12- 65 8 24 24 V 17 35 3 3 3 3 392 296 22 2 BL $ $ $ $ $ $ $ $ $ S 7 7 6 8 4 4 4 50 56 8 8 V 17 35 33 2 35 29 214 2 2 2 NP $ $ $ $ $ $ $ $ $ $ gh ) ) Hi 1 1 t 0 3 5 4 e 25 96 33 3 55 55 52 5 ( 17 1 399 3 3 35 4 28 212 2 2 2 (38 alu esen r V P $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) 9 5 5 2 4 1 h 7 00 89 80) w 136 1 03 065 989 3 271 ,06 ,0 ,0 ,033 ,47 ,400 ,669 , o ( ( l 1,. 1, 1 1 7 6 5 8 8 3,288 4,,3 2, Cas F $ $ $ $ $ $ $ $ $3 $ $ $ $ $ $ $2, 1 6 3 4 4 2 1 1 2 66 9 5 8 67 V 148 114 1 1 1 1 BL $ $ $ $ $ $ $ $ $ S 1 1 1 1 0 6 9 3 3 1 2 00 7 0 5 5 8 V 15 13 1 1 1 1 NP $ $ $ $ $ $ $ $ $ $ erate d ) 1 t 7 5 o 0) 0 6 4 4 4 e 13 1 03 9 5 5 (2 M 12- 11 184 1 1 2 38 3 25 2-42 290 2 2 ( alu esen r V P $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) 5 0 9 9 5 5 5 4 h 00 36 80) 4 40 w 774 77 77 3 82 21 27 ,5 ,6 ,550 , , , o ( (1 l 1,4 1 1 2 3,17 3,966 6,29 5 5 2,375 Cas F $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $4 ) ) ) ) ) ) ) 9 3 6 5 8) 4) 2-) 1 V 96 5 96 9 58 6 ( (7 ( ( ( ( ( (1 (11 (13 BL $ $ $ $ $ $ $ $ $ S ) ) ) ) ) ) ) ) 1) 7) 6 4 4 4 13 9 9 53 59 8 8 V (7 (50 ( ( ( ( ( ( 13 (1 ( NP $ $ $ $ $ $ $ $ $ $ w ) ) t 0 3 5 5 5 8 e Lo 1 78 93 56 59 50 6 80 8 96 (2 13 128 12 1 1 1 1 1 1 alu (3 old thinned plots with a second thin at age 14 and final harvest at age 18 for the age at 18 for final low old 14 and harvest thin age thinned plotsat second with a - V $ $ $ $ $ $ $ $ $ $ Presen $ $ $ $ ) ) 0 0 7 3 6 6 8 2 4 year 1 1 1 00 65 5 8 8 h 2-0 63 - w 1 033 96 9 3 6 5 5 88 8 48 962 ,278 , , o ( ( l 1, 1, 1,3 1,4 3 3 3 2-, 2-,4 Cas F $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ 7 9 6 6 5 2 4 4 99 7 6 62 2 .2 . . . 6 6 tal .71 3. 6. 0 0 5 2.2 1. 1. 6 5.53 4.28 00 6 To 7 3 6 5 5 89.8 11 13 17 10 14 187.41 1 1 1 ) 1 5 s 0 0 55 6 13 n w 00 00 00 74 0 .4 . 8. . . . . o t 4.13 1.42 2.1 0. 0 0 0 0 Sa ( 77.1 39.00 59 9 20 121. 1 e 1 0 0 5 S 62 59 58 08 0 hnn .4 .72 . 00 00 00 . . . N o 1. 1.01 5 4. 4. 0 0 C 52 6 52 5 5 41.7 43. 48.74 47.08 4 2 V 6 0 7 8 3 4 4 2 96 0 62 6 6 8 26 .5 .28 . . . . 3. 1. 1.64 9.39 7 7 0 9 4.24 Pulp 18 14 18.18 1 1 1 1 2 33. 3 5 5 20. 10 8 8 6 6 4 4 0 14 10 10 10 10 12 1 1 1 1 22 2 2- 2-0 24 Year e . e r r ! b a Appendix I. Financial analysis of the 10 the of analysis Financial Appendix I. moderate the pricing pricing ageinterest. stumpage 16 for and 15% and at high stumpage t After After Fert Befo Befo Es Thin2- Thin 55

7 7 8 8 8 1 5 2- 1 1 77 30 6 6 2 2 V - 9 8 2- 2-4 4 ,5 ,9 ,801 , 1,2- 1, 1 1 1 2- 2-, BL $ $ $ $ $ $ $ $ $ $ $2,11 $2,2 1 9 2- 2 11 1 69 4 V 5 85 2 ,411 1,4 1,7 1,098 1,29 1,598 1,783 1,806 1 NP $ $ $ $ $ $ $ $ $ $ $ gh ) Hi 1 7 5 8) 8 nt e 1 06 93 59 6 6 85 4 { 380 990 7 7 8 2 . ,4 ( alu ese 1, 1, 1,5 1,4 1,73 1,300 1,099 1,470 1 r V P $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) ) 1 0 7 9 6 2- 2 2 h 19 00 0 6 89 8 14 46 4 4 w 17 5 3 2-27 o ,1 ,86 ,4 ,392 , {1 { l 1 1 3,9 3,5 3,06 5, 6 4,7 Cas F $ $ $2,7 $4 $5 $ $ $ $ $ $2-,1 $ $ $ $ 2 9 53 28 V - 11 727 959 41 2-17 2-17 ,369 , ,482 , 1,4 1,474 1 1 1 BL $ $ $ $ $ $ $ $1,1 $1 $ $ S 5 2 91 96 69 7 V 668 808 896 8 4 2 1P 1,033 1,186 1,12 1,169 l\ $ $ $ $ $ $ $ $ $ $ $ erate d 1 7 8) 0) o 3 3 4 4 e nt 9 56 6 2- 4 20 ( M 71 93 38 939 7 550 5 2- ( alu ese 1, 1,3 1,0 1,116 1,067 1,08 r V P $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) ) 1 1 7 3 3 4 4 2 h 12 63 7 60 9 5 w 100 380 393 8 8 }4 ,4 ,2 , o ( ( l 1,35 1,95 1,53 2,55 2 3,1 3 3 Cas F $ $4,4 $3,985 $ $ $ $ $ $ $ $ $ $2 $ $ ) 7 5 8) 4 4 2 ( V 21 93 0 5 8 4 - 1 704 51 680 7 3 517 6 4 (1 BL $ $ $ $ $ $ $ $ $ $ $ S ) ) 0 7 3 5 8 ( 3 8 V 2- 68 119 130 325 380 3 555 56 5 4 2 ( NP $ $ $ $ $ $ $ $ $ $ $ w 6 8) 8 8 0) 9 3 9 4 nt e Lo 77 7 7 6 2- 2- ( 77 38 339 63 686 664 3 6 5 5 8 444 48 alu ( ese r $ $ $ $ $ $ $ $ $ $ $ $ $ $ P old thinned plots with a second thin at age 21 and final harvest at age 27 for the age at 27 for final low, old 21 and harvest thin age thinned plotsat second with a - ) ) 1 1 1 3 2 00 72 62 8 44 h 77 380 56 9 838 w V 2 (1 ( -,147 o year 1, 1,5 1,20 1,953 1,363 l 2-,306 2-,7 2,48 2 - Cas F $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ 7 9 4 7 0 2 0 82- 2 05 03 63 .1 . . 2-2 tal . . 3.8 9.95 0 6. 6 8.9 4. 6 18.36 06 05 To 91.9 61. 7 6 8 2- 4 14 12 12 1 1 1 is of the 9 is the of ) 6 5 6 s 7 5 16 77 80 8 n w 00 00 00 9 .4 . . . . o 3. 5 t 2. 0 0 9 Sa 4.1 { 11.2 33. 76.90 89. 2- 4 22.85 e 0 6 6 6 8 0 2 0 S 72 7 68 2 lum 0 .47 .39 . . . . . N o 1.3 9.58 3.2 6 4.4 C 74 55 7 28 2 38 68 36.36 3 4 20.37 V 0 0 6 6 3 00 95 68 84 .2- .1 .3 .89 .33 . . 6. 6.35 6.60 6 6 5 2- Pulp 14 13 12- 11. 12.78 1 2- 26.35 2 2 2 2 1 1 2 1 7 9 5 3 0 9 8 11 13 15 19 1 27 2 2 2 2 2- Year e 2 . r b er a t Appendix J. Financial analys J.Appendix Financial high stumpage and 5% at pricing interest.moderate, After Aft Fert Befo Es Thin2 56

5 6 5 5 8 4 9 87 8 47 2-8 4 1 273 24 2 328 3 3 3 3 40 LV B $ $ $ $ $ $ $ $ $ $ S 0 0 3 6 4 1 31 3 48 V 11 22- 274 277 2 357 3 3 3 274 P N : $ $ $ $ $ $ $ $ $ $ $ gh ) Hi 1 2 0 4 nt e 20 30 0 3 8 41 47 e (47) 7 535 5 5 561 55 3 6 478 481 4 4 223 s ( alu e r V P $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) 0 3 7 5 5 h 8 2-4 90 6 42 2 4 w 3 5 8 8 2-7 9 ,5 ,151 ,311 ,227 o (100) ( l 1, 1,1 1 3, 6, 5,636 6 4 Cas F $ $ $ $ $ $ $ $4, $ $2)02 $3 $2,417 $ $ $ ) 3) 5 95 90 50 53 95 41 2-2- {4 15 150 1 1 159 LV ( B nd final harvest at age 21 for the age at 21 for nd final low, harvest $ $ $ $ $ $ $ $ $ $ $ ) 0 0 9 9 4 12- 13) 35 7 7 50 84 2-1 4 4 V ( 13 1 1 1 1 ( P e t N : $ $ $ $ $ $ $ $ $ $ $ era d ) 0 7 9 5 5 2 nt e 13 00 77 9 87 8 06 4 4 6 e (47) Mo 161 31 3 3 3 506 3 3 3 3 4 4 4 s ( alu e r V P $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) ) 2- 2 0 0 7 7 3 3 3 4 h 9 6 5 88 8 8 8 w 100 00 39 0 3 814 8 951 o ,5 ,55 , ( ( l 1, 1,3 1,74 5 3,5 Cas F $ $3,005 $ $ $ $ $ $ $ $4, $2 $2,3 $4 $ $ ) ) ) ) ) ) 7) 0 6) 1 V 72) 3 8 (88) ( 101 139 139 103 139 1 3 (2 (118) ( ( ( ( ( ( ( BL $ $ $ $ S $ $ $ $ $ $ ) ) ) ) ) ) ) ) ) ) ) 0 9 9 9 6 6 4 76 93 30 8 V (7 ( ( ( 131 (11 (11 (11 (2 (18 (13 ( NP $ $ $ $ $ $ $ $ $ $ $ w ) 1 7 0 4 nt Lo 99 39 3 8 e (47) 19 196 s 2- 2-43 288 248 217 2 31 3 251 212 aine e ( r V $ $ $ $ $ $ $ $ $ $ $ $ $ $ old 17 a thin age thinned plotsat second with a P - ) ) 1 0 0 0 8 8 2- 2 13 00 72 0 60 3 6 6 8 4 4 h w 56 503 3 8 8 8 2 2 year ,1 ,5 ,5 ,069 , , (1 ( o - l 1, 1,4 1 1 1 3 2- 2- 2,2-2-2 Cas F $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ 1 9 7 8 1 1 0 3 5 3 0 7 0 .3 . . 96 6 tal .2- .1 .0 . . 6.3 6 6 6 6 4. 06 To 69 3 6 84.8 8 4 2 12 138 148 100.19 114.17 1 ) 7 8 s 0 3 5 24 0 2-5 w n 00 0 . . . a .1 .12- . o 1.9 1 5.66 5 8.20 t 0. 0.00 0 9 S 4 2.1 ( 1 96 5 2- 42.68 e 7 7 7 9 6 8 8 2- 72 90 6 28 hnn 00 .3 .3 . . . . NS o 1.5 6.5 3.53 6 5 8.47 0 C 21. 38 37 39.3 55 3 6 4 4 4 20.37 V 7 4 7 5 5 8 8 6 6 2- 79 0 9 6 6 2 .1 .1 .3 .4 .20 . . . 6.35 6 6 6 6 5 4 4 Pulp 12. 13. 14. 13.98 1 1 1 1 2-5 2 2 2 1 9 7 2 9 5 5 0 9 8 1 13 17 17 1 1 1 2-3 21 2- 27 2 Year e r ab. t Appendix K. Financial analysis of the 9 the of analysis Appendix Financial K. high stumpage and 10% at pricing interest.moderate, After After Fert Befo Es Thin2 57

) ) ) ) ) ) ) ) ) 1 1 1 0 3 9 2 7 5 9 9 (70 (92) ( ( ( 181 (1 (18 (20 (127) (12 ( BLV $ $ $ $ $ $ $ $ $ $ s ) ) ) ) ) ) ) ) ) 1 1 9 9 6 5 8 4) 6 6 48 V (8 (8 (87) ( ( 14 177 (1 (10 (11 (20 ( ( P N $ $ $ $ $ $ $ $ $ $ $ gh ) t Hi 1 1 0 3 6 6 8 4 4 n e 5 5 8 8 32 6 6 6 (33) 184 12 1 303 3 3 21 244 2 2 2 2 se ( alu V Pre $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) 1 1 7 0 9 8 3 9 h 0 6 6 80) 24 5 w 66 3 5 87 8 0 227 2 o ,71 ,59 ,747 ,370 , , , , (1 ( l 1, 1 3 6 6 5 2 4 Cas F $ $ $ $ $ $ $7 $ $2,702 $2,040 $ $ $ $ $ ) ) ) ) ) ) ) ) ) ) 7 7 6 6 5 8 4 4 4 7 9 9 6 6 V 2 2- 2-27 20 L (175) (1 (1 (1 (22 (18 (24 ( ( ( ( B $ $ $ $ $ $ $ $ $ $ S ) ) ) ) ) ) ) ) ) 1 3 8 3 2 93 63 9 6 6 17 17 177 1 1 1 242 (1 (2-21) (220) (2 ( ( ( ( ( ( ( e t NPV $ $ $ $ $ $ $ $ $ $ $ era ) ) d t 0 0 3 o 2- n e 93 90 92 59 56 9 8 4 e (3 M 181 177 133 112 1 1 1 1 3 220 2 ( alu es V Pr $ $ $ $ $ $ $ $ $ $ $ $ $ $ ) ) 1 1 0 0 9 9 9 4 2 h 09 72 0 9 9 80 87 w 95 393 32 7 3 8 8 47 27 ,3 ,35 , o , (1 ( l 1, 1,4 1 3 5, 4,873 4 2, Cas F $ $ $ $ $2,07 $ $3 $ $ $ $ $ $ $ $ ) ) ) ) ) ) 5 8 8 2 14 9 9 355 30 3 LV (2-81) (2-91) (321) (2 (2 (281) (277) (32 ( ( ( B $ $ $ $ $ $ $ $ $ $ S ) ) ) ) ) ) ) ) ) 7) 7 7 9 9 2- 1 93 65 65 0 9 6 5 V 259 P (2- (2- (3 (3 (2-77) (27 (2 (2 (2 (2 ( N : $ $ $ $ $ $ $ $ $ $ $ w ) ) o 7 7 0 3 9 3 6 6 nt e L 09 70 3 9 5 8 8 (3 se 11 121 13 111 148 117 1 3 alu ( V old thinned plots with a second thin at age 15 and final harvest at age 19 for the age at 19 for final low old 15 and harvest thin age thinned plotsat second with a $ $ $ $ $ $ $ $ $ $ $ $ $ $ Pre - ) ) 1 0 7 0 9 4 2 2 1 71 0 9 6 h 59 w 90 028 56 838 277 6 year 2 2 , , , as (1 o (38 - l 1,2.Ql 1,27 1 3 3 2,0 2-,722- 2,4 C F $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ 9 3 5 .42 03 66 69 0 6 20 tal .7 . . . . 1.24 1.42 9 7. 3. 6 0 6 6 13.12 5 6 27.13 To 64 6 9 8 4 22.37 2 13 1 1 1 1 ) 1 2 8 s 0 0 0 5 0 9 w 44 56 .30 .03 . . . 0 0 0 a on .59 . . . 5 5 8 t 3. 0 0 0 S 4.1 ( 1 72.18 59 8 95 44.83 2 e 0 6 8 4 4 0 0 72 09 0 6 84 hnn 0 .1 .88 . . . . . o 1.1 9 8.28 0J2 6.5 9 0. CNS 12 55 52 5 42 47 4 4 20.37 4 V 1 0 9 5 6 6 6 5 3 5 5 8 6 6 .1 .3 .7 .20 .2 . . 90 . 6 9 6 6 6 6 5 8 Pulp 17.1 18.1 17.71 18.7 17.2 1 1 1 2 2 2 2 9 5 5 5 5 ear 0 8 9 11 13 17 1 1 1 1 2 2-9 21 23 27 Y e . r tab Appendix L. Financial analysis of the 9 the of analysis Financial Appendix L. stumpage 17 pricing thestumpage age moderate for and high and interest.pricing 15% at E.s Fert Befo Thin2- After After 58