1

Timber Growth and Yield in the Black Hills National Forest: 1

A Changing Forest 2 3 Authors ............................................................................................................................................ 2 4

Abstract ........................................................................................................................................... 3 5 KEY POINTS ................................................................................................................................. 4 6

DATA ........................................................................................................................................... 10 7

Data Acquisition ....................................................................................................................... 12 8

1962....................................................................................................................................... 12 9

1984....................................................................................................................................... 13 10 1999....................................................................................................................................... 14 11

2011....................................................................................................................................... 14 12

2017....................................................................................................................................... 16 13

2019....................................................................................................................................... 17 14 Data Compilation ...................................................................................................................... 17 15

Gross growth components..................................................................................................... 18 16

Annual Mortality Estimates and Trends ................................................................................... 18 17

Trends in Growth, Mortality, Harvests, and Standing Live Inventory ..................................... 19 18 Tree Selection by Mountain Pine Beetles and Timber Harvest ................................................ 20 19

Volume per Acre Changes in Growth and Mortality ................................................................ 21 20

Scenarios ................................................................................................................................... 21 21

Scenario 1.............................................................................................................................. 25 22 Scenario 2.............................................................................................................................. 25 23

Scenario 3.............................................................................................................................. 25 24

Scenario 4.............................................................................................................................. 26 25

Scenario 5: ............................................................................................................................ 26 26 Scenario 6: ............................................................................................................................ 27 27

CONCLUDING REMARKS ........................................................................................................ 27 28

29 30 31 32

2

Authors 33

34

Russell T. Graham is a Research Forester (Silviculturist) with the USDA Forest Service, Rocky 35

Mountain Research Station, Moscow, Idaho. He started his Forest Service career in 1966 as a 36

high school student working on the Bear Lodge Ranger District, Black Hills National Forest. His 37

research activities have included studying the role that coarse woody debris plays in forests, 38

addressing large-scale ecosystem assessment and planning, describing northern goshawk habitat, 39

and evaluating the impacts of major wildfires. 40

41

Mike A. Battaglia is a Research Forester with the USDA Forest Service, Rocky Mountain 42

Research Station, Fort Collins, Colorado. His research focuses on developing and implementing 43

innovative management strategies to enhance forest resiliency to disturbances and evaluating the 44

subsequent ecological impacts of these activities. 45

46

Theresa B. Jain is a Research Forester (Silviculturist) with the USDA Forest Service, Rocky 47

Mountain Research Station, Moscow, Idaho. Her research focuses on developing, implementing, 48

and evaluating alternative silvicultural systems and methods for addressing integrated fuel 49

treatments. 50

51

52

53

54

3

Abstract 55

56

Over the past several years, the Black Hills National Forest (BHNF) has experienced mountain 57

pine beetle epidemics, wildfires, and other natural disturbances that reduced live tree volume. At 58

the same time, timber harvests increased on the BHNF. To better understand the changed 59

landscape, BHNF Leadership and stakeholders agreed upon an intensified Forest Inventory and 60

Analysis (FIA) sampling grid to assess the current trends in ponderosa pine (Pinus ponderosa) 61

standing volume, growth, and mortality over the past several years. This report used these FIA 62

data to develop a series of harvesting scenarios that provide future estimates of timber harvests 63

for the BHNF. If the current (2019) annual sawtimber harvest of 153,534 CCF per year (CCF = 64

100 cubic feet) were to continue, the live sawtimber volume will be depleted in the next several 65

decades. To meet the current allowable sale quantity (ASQ) of 181,000 CCF as described in the 66

BHNF Plan, a standing live sawtimber volume of approximately 12 million CCF would be 67

required. However, current standing live sawtimber volume is approximately 5.9 million CCF. 68

Furthermore, the current forest conditions in 2019 and probable growth and mortality estimates 69

suggest a saw timber program on the BHNF with an annual harvest of 70,000 to 115,000 CCF 70

per year would be possible. Nevertheless, these harvest levels would allow the live sawtimber 71

inventory amounts to increase to 6 million CCF in approximately 60 years and return to the level 72

needed to support ASQ as identified in the current forest plan (181,000 CCF) within a century. 73

74

4

KEY POINTS 75

• These findings are dependent on estimates of standing live volume, tree growth rates, and 76

especially mortality rates disclosed by Forest Inventory and Analysis (FIA) data. Future 77

climate, weather, mountain pine beetle activity, and wildfire are unknown and potential 78

forest dynamics and growth can only be inferred from past conditions. 79

• All scenarios assume no harvest reduction for other resources (e.g., wildlife, botany, 80

aquatics, and so on) or for Forest Plan adjustments. However, Black Hills National Forest 81

(BHNF) may have restrictions that could alter the amount of area treated and the volumes 82

removed. 83

• The intensified 2019 FIA sampling scheme for the BHNF provided robust and high 84

quality data. 85

• Ponderosa pine forest growth rates of trees (5 inches plus in diameter at breast height; 86

d.b.h.) from 1962 through 2019 ranged from 2.3 to 2.7% while mortality rates varied 87

from 0.16 to 3.07% as wildfires and mountain pine beetles killed trees. 88

• The current conditions of the BHNF in 2019 do not support a Forest Plan allowable sale 89

quantity (ASQ) of 181,000 CCF (1 CCF = 100 cubic feet) of sawtimber (9 inches and 90

greater d.b.h.), nor do these forest conditions support an annual harvest of 153,534 CCF 91

that occurred in 2019. 92

• To sustain the Forest Plan ASQ of 181,000 CCF would require a standing live sawtimber 93

volume of more than 12,000,000 CCF. Current (2019) standing live sawtimber volume is 94

5,995,428 CCF. 95

• Using 2019 FIA data, several scenarios using an annual sawtimber growth rate of 2.5% 96

were evaluated, as well as varying harvest levels, mortality rates, and their timing and 97

5

longevity. A harvest scenario with 1.04% mortality rate (i.e., long-term conservative 98

estimate) indicated an annual sawtimber harvest of 70,000 CCF. Using 2019 FIA data as 99

a starting point and an annual mortality rate of 0.26% (i.e. optimistic), an annual 100

sawtimber harvest of 115,000 CCF could be realized. 101

• Both growth and mortality rates could be modified by stand management. In particular, 102

precommercial thinning of tree regeneration by age 30, both through mechanical means 103

or prescribed fire, could significantly increase residual tree growth rate and shorten the 104

time in which trees become merchantable. Such thinnings could be designed to make 105

forests resistant and resilient to mountain pine beetle attack and wildfire, reducing 106

mortality rates over time. 107

108

6

Introduction 109

110

The BHNF has supported a thriving forest industry for over 100 years (Freeman 2015). The 111

BHNF is approximately 1.2 million acres in size, of which the Forest Plan Amended in Phase II 112

(USDA FS 2005, Appendix G-3) identifies 865,890 acres as suitable and available for timber 113

harvest. In 2019 the USDA Forest Service, Forest Inventory and Analysis Program (USDA 114

2019) identified 765,733 acres of timberland: (suitable), as forestland that is producing or is 115

capable of producing 20 cubic feet per acre per year of industrial wood in natural stands and not 116

withdrawn from timber utilization by statute or administrative regulation. Lands inaccessible and 117

inoperable were included. The current Black Hills National Forest Plan Amended in Phase II 118

(USDA FS 2005) identifies an allowable sale quantity (ASQ) of 181,000 CCF (1 CCF = 100 119

cubic feet) of sawtimber and 21,000 CCF of roundwood. 120

121

Mountain pine beetle (MPB) (Dendroctonus ponderosae) epidemics and wildfires have impacted 122

forests of the BHNF for centuries. Both occur at different frequencies and intensities that 123

influence forest characteristics. The Black Hills have experienced MPB epidemics recurring 124

somewhere in the Forest about every 20 years (fig. 1), with notable events in the early 1900s and 125

one from 1998 through 2016, which killed tens of thousands of trees in portions of the South 126

Dakota Black Hills (see Graham et al. 2016 for a comprehensive description of MPB, their 127

history, life cycle, attempted control, impacts, and suggested forest management strategies to 128

ameliorate their impacts) (figs. 1, 2). 129

130

131

7

Wildfires are also a major determinant affecting the character of Black Hills’ forests. Before 132

European settlement of the Black Hills, wildfires burned on average every 10 to 31 years, 133

depending on elevation (Brown et al. 2008; Brown and Sieg 1996; Brown and Sieg 1999; Hunter 134

et al. 2007). However, since the 2000s, wildfire activity has increased and burned hundreds of 135

thousands of acres (fig. 2). 136

137

Mountain pine beetle epidemics and wildfires in conjunction with timber harvest changed forest 138

conditions in the last two decades. Recognizing this change, in June 2017 the BHNF Leadership 139

convened a working group to develop questions of interest. These questions centered on 140

developing a rigorous and statistically sound understanding of the commercial forest within the 141

suitable land base (timberland) as defined by FIA on the BHNF. This working group consisted of 142

BHNF staff, industry representatives, and representatives from the South Dakota and Wyoming 143

State Foresters’ offices. The working group agreed that an intensified FIA sampling be 144

conducted to assess the current trends in standing volume, growth, and mortality. From 2017 145

through 2019, the USDA Forest Service Northern Forest Inventory and Analysis Program 146

(Northern FIA) inventoried the forests of the BHNF. Rather than using their normal plot 147

intensity of one plot for every 6,000 acres, they intensified the number of plots to one for every 148

3,000 acres and measured them during a 3-year period. As a result, Northern FIA addressed the 149

following questions produced by the Working Group in 2017 and finalized by the BHNF 150

Leadership on November 26, 2019. 151

152

• What is the standing live volume estimate? 153

• What is the annual gross growth estimate? 154

8

• What is the annual net growth estimate? 155

• What is the net growth to removal ratio? 156

In addition to the Working Group questions addressed by the FIA the Working Group also 157

asked: 158

• What is the ability to produce an available sustained yield on the Forest 159

(timberlands/suitable base) for the next decade and what is the methodology for 160

producing this estimate? 161

The Leadership of the Black Hills National Forest on November 13, 2018 at 2:15 PM and 162

codified by the Leadership of the BHNF on November 26, 2019 at 7:44 AM, expanded and 163

modified the last question developed by the Stakeholder Group to have RMRS address the 164

following questions. 165

• What impact does the current 2019 forest condition (i.e., standing volume, mortality, and 166

growth) have on the out-year timber program of harvesting at current levels compared to 167

other harvest level scenarios using probable growth and mortality estimates? 168

• What is a sustainable timber harvest estimate for the BHNF using the 2019 Northern FIA 169

data assuming rationale tree mortality and growth rates informed by those of the past? 170

• What would be the standing inventory volume necessary using reasonable growth and 171

mortality estimates to sustain a sawtimber ASQ of 181,000 CCF? 172

173

In 2018, a preliminary analysis was performed using the 2017 Northern FIA data to answer the 174

above questions, resulting in a report titled November 26, 2018 Internal Report: Timber Growth 175

and Yield in a Changing Forest Black Hills. (Document on file, USDA Forest Service Rocky 176

Mountain Research Station, Fort Collins, CO). On November 26, 2019, the Leadership of the 177

9

the BHNF asked the Rocky Mountain Research Station (RMRS) to revise this internal report 178

including the completed 2019 data collected by Northern FIA. 179

180

10

DATA 181

182

The following description of the National Forest Inventory and Analysis (FIA) program was 183

adapted from https://www.fs.fed.us/rm/ogden/about/InteriorWestFIAbrochure.pdf (USDA FIA 184

n.d.), accessed on February 1, 2020: 185

186

The National Forest Inventory and Analysis (FIA) program of the USDA Forest Service 187

has been surveying lands since 1930. Their mission is to manage and update a 188

comprehensive inventory and analysis of the present and future conditions of the 189

renewable resources of the forest and rangelands of the United States. This nationwide 190

program consists of four regional FIA units. In cooperation with the USDA Rocky 191

Mountain Research Station and the Northern Research Station, the Interior West (IW-192

FIA) unit and the Northern FIA unit are responsible for creating and maintaining a 193

comprehensive forest inventory for the Black Hills National Forest. 194

195

The program consists of three types of data collection. Phase 1 utilizes remote sensing 196

imagery or aerial photography to classify land as forest or nonforest to create broad 197

scale maps of forest attributes and landscape patterns. Phase 2 uses randomly 198

established permanent field plots distributed across each State at a sample intensity of 199

about one plot per 6,000 acres. Each field plot contains a cluster of four subplots that 200

covers about 2.5 acres. Most phase 2 data are related to the tree and understory 201

vegetation components of the forest. Phase 3 is designed to further assess forest health by 202

sampling a subset of phase 2 plots with additional health indicator measures such as soil 203

11

attributes, down woody material, plant species occurrence, lichen diversity, and the 204

extent of ozone injury. Plots are visited only during the growing season. This sampling 205

design allows for the estimation of sampling errors for each of the forest attributes of 206

interest. 207

208

In the FY2000 Consolidated Appropriations Bill (PL106-113), Congress included 209

language that modified the Food Security Act of 1985 (7 U.S.C. 2276(d)) to add FIA data 210

collection to a list of items requiring confidential treatment. This law prevents FIA from 211

revealing plot locations in such a way that individual ownership can be determined, and 212

specifies criminal penalties for violations. Current FIA policy (Forest Service Handbook 213

Interim Directive number 4809.11-2003-1) does permit public release of FIA sample 214

coordinates rounded to the nearest 1/2 to 1 mile with a random set of locations swapped 215

within a State. Such inexact coordinates prevent association of individual sample 216

locations with individual owners, but will still meet the needs of users looking for 217

approximate geographical location of data. 218

219

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220

Data Acquisition 221

222

We obtained standing live inventory, growth, and mortality values from the 1960s through 2019 223

from a number of FIA sources. Below is a list of the reports and information we obtained from 224

them. 225

226

1962 227

228

Choate, Grover A.; Spencer, John S. Jr. 1968. Forests in South Dakota. Resource Bull. INT-8. 229

Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range 230

Experiment Station. 52 p. 231

232

This publication reported data collected as a cooperative effort between the USFS Rocky 233

Mountain Region (Region 2) and the Intermountain Forest and Range Experiment Station. Trees 234

were measured at 137 locations within the South Dakota portion of the Black Hills and on Custer 235

National Forest lands to estimate volume, growth, and mortality. About 99% of the commercial 236

forest lands, which are those lands capable of growing 20 cubic feet per acre per year and not 237

withdrawn from timber harvest by statue or administrative regulation, within the Black Hills 238

occur on the BHNF. Data were presented for ponderosa pine trees 5 inches d.b.h. and greater 239

growing on commercial lands. In later FIA reports, these lands were referred to as timberlands. 240

Data collection for this report began in 1960 and was completed in 1965. Thus, the summaries 241

and tabulations in this report are termed 1962 as this date represented the center of the collection 242

13

period. Merchantable trees were defined as those with a 5-inch d.b.h. or greater, with a 4-inch 243

top, and those having a 1-foot stump. 244

245

1984 246

247

Collins, Dennis C.; Green, Alan W. 1988. South Dakota’s timber resources. Resource Bull. INT-248

56. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 249

28 p. 250

251

Data in the report were collected by the Intermountain Research Station in 1983. The report does 252

not specify how many plots were sampled. Data reported were for the South Dakota portions of 253

the Black Hills and Custer National Forests. The report describes volume, growth, mortality, and 254

removals from forested lands capable of producing wood. However, the report doesn’t specify if 255

these data include values from lands withdrawn by statue or administrative regulation. Data 256

presented are for merchantable ponderosa pine trees defined as those having a d.b.h. of 5 inches 257

or greater, a 4-inch top, and a 1-foot stump. 258

259

14

1999 260

261

DeBlander, L.T. 2002. Forest resources of the Black Hills National Forest. Ogden, UT: U.S. 262

Department of Agriculture, Forest Service, Rocky Mountain Research Station. 13 p. 263

264

The Interior West Forest Inventory and Analysis (IW-FIA) Unit of the Rocky Mountain 265

Research Station conducted a periodic inventory on the BHNF using a nationally standardized 266

plot design. This survey included both the South Dakota and Wyoming portions of the BHNF. 267

There were 205 plots sampled on the BHNF; of these, 173 plots sampled only forest conditions, 268

22 sampled both forest and nonforest conditions, and 10 sampled only nonforest conditions. The 269

report describes volume, growth, mortality, and removals from all lands administered by the 270

BHNF, including reserved lands which made up 1% of the total. Data presented were for 271

ponderosa pine trees 5 inches d.b.h. and greater. These data do not incorporate changes in the 272

standing live inventory caused by the 130,000 acres that burned in the Black Hills between the 273

inventory and the publication date. 274

275

2011 276

277

Walters; Brian F.; Woodall, Christopher W.; Piva, Ronald J.; Hatfield; Mark A.; Domke, Grant 278

M.; Haugen, David E. 2013. Forests of the Black Hills National Forest 2011. Resource Bull. 279

NRS-83. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern 280

Research Station. 36 p. 281

282

15

Information on the condition and status of forests in the BHNF was obtained from the Northern 283

FIA Program. Sampling for this report covered both the South Dakota and Wyoming portions of 284

the BHNF. Data for this report included the most recent 5-year inventory period for the South 285

Dakota portion of the BHNF, 2007-2011, and the 2005 Wyoming data. Growth, removals, and 286

mortality estimates were made using the 2002-2006 South Dakota inventory and the 2000 287

Wyoming inventory. The 2000 periodic inventory for Wyoming was valid for growth 288

remeasurement estimation because the plot design was similar to the national annual inventory 289

plot design; however, because of regional differences in data compilation between Northern-FIA 290

and IW-FIA, unique data compilation procedures had to be developed (Walters et al. 2013). Data 291

were collected on 228 plots. Data we used from this report were for ponderosa pine 5 inches 292

d.b.h. and greater growing on timberlands. Merchantable volume was presented for trees 5 293

inches d.b.h. and greater to a 4-inch top and allowing for a 1-foot stump. 294

295

16

2017 296

297

Northern Forest Inventory Analysis (unpublished) 298

299

USDA Forest Service, Forest Inventory and Analysis Program, Nov 2018. Forest Inventory 300

EVALIDator Desktop Version 1.7.2.00. St. Paul, MN: U.S. Department of Agriculture, Forest 301

Service, Northern Research Station. 302

303

Approximately 225 plots were sampled by Northern FIA between the years 2011 and 2016 304

across South Dakota and Wyoming within the BHNF. During this time, MPB were killing 305

thousands of trees, but by 2012 the mortality epidemic was declining (fig. 1). In 2017, Northern 306

FIA added to their sampling intensity within the Black Hills and 130 additional plots were 307

completed. These 355 plots provided the data for the 2017 estimates. Growth, mortality, 308

removals, and standing live volume for merchantable ponderosa pine 5 inches d.b.h. and greater 309

and the sawtimber portion defined as trees with 9 inches d.b.h. and greater were tabulated that 310

occurred on timber lands. Merchantable volume for 5 inch and greater trees were to a 4-inch top 311

and sawtimber volumes were computed to a 7-inch top. Both merchantable volume classes used 312

a 1-foot stump. 313

314

315

316

317

17

2019 318

319

Northern Forest Inventory Analysis (unpublished) 320

321

USDA Forest Service, Forest Inventory and Analysis Program, Tue Nov 26 2019 10:32:35 AM. 322

Forest Inventory EVALIDator Desktop Version 1.7.2.00. St. Paul, MN: U.S. Department of 323

Agriculture, Forest Service, Northern Research Station. 324

325

The 2019 estimates utilized the 130 plots from 2017, an additional 147 plots were measured in 326

2018, and 161 plots were measured in 2019. As a result, 438 plots (one plot per 3,000 acres 327

compared to normal FIA densities of one plot per 6,000 acres) were available for the 2019 328

analysis (fig. 3) across South Dakota and Wyoming within the BHNF. Growth, mortality, 329

removals, and standing live volume of the merchantable 5 inch plus and 9 inch plus were 330

estimated the same for 2019 as estimated for the 2017 data. 331

332

Data Compilation 333

334

Using the above sources, data were compiled for the ponderosa pine forests of the BHNF from 335

1962 through 2019. In addition, the 1962 and 1984 reports included a small quantity of white 336

spruce (Picea glauca) volume as the publications only reported softwoods. 337

338

339

18

Gross growth components 340

341

Forest growth is determined by climate and soil properties and is distributed over various 342

components (fig. 4). The FIA reports we tabulated did not include metrics for trees smaller than 343

5 inches d.b.h (table 1). See Concluding Remarks on how these small trees could be managed to 344

redistribute their growth to fewer stems and move them in to the merchantable class faster. 345

346

Nearly 160,000 CCF were accumulated on ponderosa pine trees 5 inches d.b.h. and greater each 347

year on timber lands within the Black Hills by 2019 (fig. 4). Of this volume, 100,000 CCF 348

accumulated on trees 9 inches d.b.h. and greater (growth on residual). Each year trees grow into 349

the merchantable class (ingrowth) and the annual growth on these trees also contribute to the 350

gross growth. Similarly, trees that died and were harvested during the measurement period also 351

contribute volume to the annual gross growth. As a result, the annual gross growth occurring on 352

ponderosa pine trees in 2019 on timberland on the BHNF was 185,049 CCF for trees 5 inches 353

d.b.h. and greater and 150,694 CCF for trees 9 inches and greater in d.b.h. (tables 1, 2; fig. 4). 354

355

Annual Mortality Estimates and Trends 356

357

Weather (e.g., wind, snow, ice), diseases (e.g., root, stem, foliage), insects (e.g., beetles, moths), 358

animals (e.g., mice, gophers, elk, cattle), and fire kill trees in the Black Hills. The low (0.16 to 359

0.26%) ponderosa pine mortality rates from 1962 to 1999 reflect the low (endemic) levels of 360

MPB activity (fig. 1) and minimal wildfire occurrence (fig. 2), leaving weather as the primary 361

mortality agent. In 2011 (Walters et al. 2013), mortality levels increased to 1.04%, which 362

19

represent the impacts of the Jasper, Ricco, Roger Shack, Battle Mountain, and other fires (figs. 2, 363

6) in combination with the commencing 2000 MPB epidemic (fig. 2). Mortality levels for trees 9 364

inches d.b.h. and greater increased from 2.48% in 2017 to 2.98% in 2019 showing the full impact 365

of the MPB epidemic (fig. 5). The high mortality rates observed in the 5 to 9 inch d.b.h. class in 366

2017 and 2019 suggest fewer trees will transition to the sawtimber size class in the future. As a 367

conservative estimate, the 1.04% mortality rate observed by Walters et al. (2013) is reasonable 368

and may reflect that the long-term mortality trend of trees killed in the Black Hills. In addition it 369

is a good estimate of what might occur in future decades. Similarly, van Mantgem et al. (2009) 370

indicated that recent trends in mortality in pines across the Western United States over the past 371

four decades have been increasing and ranged from 1 to 2%. 372

373

Trends in Growth, Mortality, Harvests, and Standing Live Inventory 374

375

The Black Hills forests have maintained a viable timber industry for over a century (Freeman 376

2015; Shepperd and Battaglia 2002). Until the 1970s, the majority of timber management in the 377

Hills utilized individual tree silvicultural systems centered on removing sawtimber sized trees 378

that provided openings for regeneration. Also during the 1960s, a pulp wood market allowed the 379

young pole sized (5 to 10 inch d.b.h.) trees to be thinned, realizing benefits from the Civilian 380

Conservation thinnings of the 1930s (Graham et. al. 2019). These forest conditions were 381

characterized in 1962 with net growth (200,830 CCF) nearly equaling gross growth (213,010 382

CCF) and a harvest (109,780 CCF) well below the amount of wood being accumulated (fig. 6). 383

In the 1970s timber management began to transition from individual tree silvicultural systems to 384

using one and two step shelterwood systems. 385

20

386

Volumes of gross growth and net growth continued to increase rather dramatically, peaking at 387

380,000 and 340,000 CCF respectively through 1999. Harvest was 204,000 CCF in 1999, and 388

40,000 CCF died (fig. 6). By 2011, the MPB began killing more trees (140,000 CCF) and net 389

growth (210,000 CCF) was far below gross growth (380,000 CCF). However, harvest continued 390

to increase to 240,000 CCF, exceeding net growth. As a result of both harvest and trees being 391

killed by MPB, live standing inventory decreased from 15,353,000 in 1999 to 13,477,960 CCF in 392

2011 (fig, 6). The downward trend in net growth continued with 1,646 CCF occurring in 2017 393

and net growth went negative to -59,654 CCF in 2019. At the same time, harvest peaked at 394

261,721 CCF in 2017, far exceeding net growth, and declined to 183,592 CCF in 2019 when the 395

net growth was negative (fig. 6), resulting in live standing inventory of 7,958,314 CCF (table 2, 396

fig. 6). 397

398

Tree Selection by Mountain Pine Beetles and Timber Harvest 399

400

From 1985 through 2012 MPB in the Black Hills, beetles preferentially selected trees from 9 to 401

16 inches d.b.h. to colonize and subsequently kill (fig. 7). Although there were exceptions, as 402

noted by the red arrow, there was good congruity among the d.b.h. of live trees available to MPB 403

to the ones they killed, as indicated by the clustering of points along the 45 degree diagonal line. 404

This similarity, is illustrated by trees being killed and living on the same plot having similar 405

means (11.2 inches; black arrow) (Graham et al. 2016). Also, trees within this diameter range 406

dominated the timber growing stock and were the preferred harvest trees. 407

408

21

Volume per Acre Changes in Growth and Mortality 409

410

In 2011, gross growth was 45.2 cubic feet per acre per year (fig. 8), indicating the forest was well 411

stocked and producing volume in excess of the 25 cubic feet per acre per year that Meyer’s 412

(1938) suggested for fully stocked ponderosa pine stands with a site index of 55 (base 100). Even 413

net productivity of 27.2 cubic feet per acre per year indicated a commercially productive forest. 414

However, by 2017 gross growth declined to 32.0 cubic feet per acre per year and mortality of 415

32.0 cubic feet per acre per year resulting in no net growth. Similar to the Forestwide values, by 416

2019 annual mortality per acre exceeded annual gross growth per acre. 417

418

Scenarios 419

420

The Leadership of the USFS Rocky Mountain Region and Black Hills National Forest (BHNF) 421

asked the Rocky Mountain Research Station to: 422

• Determine what impact does the current 2019 forest condition (i.e., standing volume, 423

mortality, and growth) have on the out-year timber program of harvesting at current levels 424

compared to other harvest level scenarios using probable growth and mortality estimates. 425

• What is a sustainable timber harvest estimate for the BHNF using the 2019 Northern FIA 426

data assuming rationale tree mortality and growth rates informed by those of the past? 427

• What would be the standing inventory volume necessary using reasonable growth and 428

mortality estimates to produce a sawtimber ASQ of 181,000 CCF? 429

430

22

To that end, we the authors, in consultation with the Leadership of the BHNF and Rocky 431

Mountain Region crafted six scenarios that directly and/or indirectly addressed the above 432

questions. All scenarios were for ponderosa pine sawtimber (trees 9 inches d.b.h. and greater) 433

growing on timberland (suitable land) defined by FIA as lands capable of producing 20 cubic 434

feet per acre per year and not withdrawn from timber management. Forest Plan constraints such 435

as slope steepness, wildlife, recreation, grazing, or other values were not considered in the 436

scenarios. All scenarios started with the 2019 ponderosa pine sawtimber average annual gross 437

growth, 150,694 CCF; average annual mortality, 178,409 CCF; average annual harvest, 153,534 438

CCF; and standing live volume of 5,995,428 CCF (table 2). Numerous combinations of annual 439

mortality rates and harvest levels could have been modeled. We choose ones we feel encompass 440

future possibilities of forest development in the Black Hills and would be applicable for 441

informing Forest planning. 442

443

The accuracy of estimating future climate, weather, wildfires, and MPB activity for the Black 444

Hills is far from perfect. The best estimate of what the future may bring, is to rely on the past to 445

make reasonable assumptions as to how future forests may develop. Our assumptions for future 446

tree growth and mortality rates were estimated using Forest Survey (precursor to FIA) and FIA 447

data from the 1960s through 2019 for timberlands in the Black Hills (table 1). 448

449

From 1962 through 2019 gross growth of ponderosa pine trees 5 inches d.b.h. and greater were 450

growing at a rate of 2.33 (2019) to 2.74% (2017) as percent of standing live volume (table 1). 451

However, in 2017 trees 9 inches d.b.h. and greater were growing at a rate of 3.12% and 2.5% in 452

2019. As a result we found no mathematically way to justify a gross growth rate to use in our 453

23

scenarios. Therefore we felt an annual growth rate of 2.5% would readily reflect what may occur 454

in the future and is well exemplified in the FIA data. 455

456

Compared to growth rates, mortality rates primarily driven by MPB and wildfires from 1962 457

through 2019 varied widely (tables 1, 2; fig. 5). For example, mortality rates occurring from 458

1962 through 1999 of 0.16 to 0.26% for ponderosa pine trees 5 inches and greater d.b.h. occurred 459

during limited amounts of MPB and wildfire activity (figs. 1, 2). By 2011, mortality rates for this 460

same tree class increased to 1.04% as a number of wildfires burned (fig. 2) and the MPB beetle 461

epidemic intensified (figs. 1, 2). As the MPB epidemic appeared to be peaking, the 2017 and 462

2019 mortality rates increased to 2.3 to 2.7% respectively for trees 5 inches d.b.h. and greater 463

(table 1, fig. 5). As MPB showed a preference for colonizing large trees (fig. 7) the mortality rate 464

for trees 9 inches and greater in d.b.h. (sawtimber) had a mortality rate of 2.5% in 2017 and a 465

3.0% rate in 2019 (table 2, fig. 5). As a result, these mortality rates reflect the impact of MPB, 466

wildfires, weather, and other disturbances and provide different rates we used in our scenarios. 467

Depending on the scenario the mortality rates varied in amount and longevity showing potential 468

futures for the timber program of the BHNF. 469

470

However, as we disused before, a conservative mortality estimate of 1.04% rate observed by 471

Walters et al. (2013) is reasonable and may reflect that the long-term mortality trend of trees 472

killed in the Black Hills. In addition, we feel this rate is a good estimate of what might occur in 473

future decades. Similarly, van Mantgem et al. (2009) indicated that recent trends in mortality in 474

pines across the Western United States over the past 4 decades have been increasing and ranged 475

from 1 to 2%. 476

24

477

All scenarios started with the 2019 sawtimber (ponderosa pine trees 9 inches d.b.h. and greater) 478

standing live volume of 5,995,428 CCF and used an annual growth rate of 2.5% (tables 1, 2, fig. 479

9). A tabulation of the values for each scenario are shown in the Appendix. 480

481

• Scenario 1: continuation of the 2019 harvest level (153,534 CCF) and mortality rate of 482

2.98% (2019) and a growth rate of 2.5% (pessimistic). 483

• Scenario 2: amount of standing volume required to sustain an ASQ of 181,000 CCF (i.e., 484

Forest Plan) using a growth rate of 2.5% and a long-term mortality rate of 1.04%. 485

• Scenario 3: reduction of harvest from 153,534 CCF (2019) to 85,000 CCF with differing 486

mortality rates (0.26 to 2.98%). 487

• Scenario 4: reduction of harvest from 153,534 CCF (2019) to 75,000 CCF with differing 488

mortality rates (1.04 to 2.98%). 489

• Scenario 5: reduction of harvest from 153,534 CCF (2019) to 70,000 CCF with differing 490

mortality rates (1.04 to 2.98%). 491

• Scenario 6: the potential harvest if mortality decreases and remains at the historical low 492

of 0.26%. However, the history of MPB activity shown in figure 1 precludes this scenario 493

from reflecting reality. 494

495

25

496

Scenario 1: This scenario illustrates the continued annual harvest of 153,534 CCF per year of 497

sawtimber from timberlands (suitable land base) that occurred in 2019 into the future. The 498

annual mortality rate of 2.98% from 2019 was used, and as in all scenarios, the sawtimber 499

growth rate of 2.5% was used (table 2, fig. 5). Under these assumptions (pessimistic), including 500

all of the components of gross growth (e.g., ingrowth, growth on mortality) sawtimber in the 501

Hills would be depleted by 2054 (fig. 9). This scenario, by far represents the worst and most 502

extreme possible future for forests of the Black Hills and its likelihood of occurring is minimal. 503

Nevertheless, provides context for evaluating and planning future timber management options 504

for the BHNF. 505

506

Scenario 2: This scenario illustrates the amount of standing live volume required to sustain a 507

harvest level of 181,000 CCF per year (Forest Plan ASQ) from timberland. The scenario assumes 508

a mortality rate of 1.04% and a 2.5% growth rate which are very possible in the future.. See the 509

earlier discussion of annual mortality estimates and trends. Using these assumptions, this 510

scenario illustrates a forest containing a standing live sawtimber volume of ≈ 12 million CCF 511

would be required to support the Forest Plan ASQ (fig. 9). 512

513

Scenario 3: This scenario illustrates reducing harvest volume from 153,534 CCF that occurred in 514

2019 to 125,000 CCF in 2020 and continuing in a linear fashion to decrease the harvest volume 515

to 85,000 CCF per year over the next 10 years (2030) (fig 10). The growth rate remained 516

constant at 2.5%, however the mortality rate decrease linearly from 2.98% to 1.04% by 2028, 517

reflecting what might occur as the MPB epidemic subsides (fig. 11). Also reflecting what 518

occurred historically between MPB epidemics (fig. 1), the scenario decreased the mortality rate 519

26

to 0.26% by 2034 and increasing the mortality rate to 1.04% in 2048. Once again showing how 520

variable mortality rates may affect future forest volumes (fig. 11). This scenario illustrates when 521

the mortality rate was at its historical low (2034) standing volume would accumulate with an 522

annual harvest of 85,000 CCF. However, when the mortality rate returned to 1.04%, reflecting 523

the 2011 value (Walters et al. 2013) standing volume decreased (fig. 12). 524

525

Scenario 4: This scenario illustrates reducing the harvest from 153,534 CCF (2019) to 125,000 526

CCF per year in 2020 and to 75,000 CCF in a linear fashion to year 2030 when it remains 527

constant (fig. 10). Growth rates remained constant at 2.5%, but mortality rates decreased linearly 528

from 2.98% to 1.04% by 2030 and remained at that level (fig. 11). These changes in mortality 529

rates would reflect the long-term trends observed in the Black Hills as discussed earlier when 530

MPB were endemic and weather and wildfire were determinants of mortality. Standing live 531

volume would gradually decrease under this scenario but remain near 5.1 million CCF through 532

the end of the century (fig. 12). 533

534

Scenario 5: This scenario illustrates reducing the harvest from 153,534 CCF (2019) to 125,000 535

CCF per year in 2020. From 2020 through 2025 the harvest was linearly reduced to 70,000 CCF 536

per year (fig. 10). Growth rates remained at 2.5%, but mortality rates decreased from 2.98% in 537

2020 to 1.04% by 2030 (fig. 11), reflecting the historical norm. This scenario illustrates when 538

harvest volume is less than net volume growth, growing stock will accumulate (fig. 12) and a 539

sustainable harvest level can be achieved. Also, depending on precommercial thinning 540

operations, growing stock amounts could likely be increased. 541

542

27

Scenario 6: This scenario illustrates the potential harvest if mortality decreases from 2.98 to 543

2.43% in 2020 and to 0.26% by 2028 (fig. 11). This historically low mortality rate did occur 544

when few wildfires burned and MPB activity was minimal (figs. 1, 2). Growth rates were 545

maintained at 2.5% and, after 2029, standing live volume increased and a potential annual 546

harvest of 115,000 CCF could be realized (fig. 10). However, with return intervals of MPB and 547

wildfires approximately 20 years such continued low mortality rates are highly unlikely. 548

549

CONCLUDING REMARKS 550

551

The intensive 2017-2019 FIA data demonstrated that the BHNF has undergone a substantial 552

decline in the ponderosa pine standing live volume. The impacts of the MPB, wildfires, and other 553

natural disturbances combined with timber harvest during the past decade contributed to this 554

decline (fig. 6). Based on these data, current live ponderosa pine sawtimber volume of 5,995,428 555

CCF will not support an ASQ of 181,000 CCF as identified in the BHNF Plan. In order to 556

produce this ASQ, a standing live ponderosa pine sawtimber inventory of approximately 557

12,000,000 CCF would be required (scenario 2). Furthermore, the current forest conditions 558

(2019) and probable growth and mortality estimates suggest an annual harvest for the timber 559

program on the BHNF in the range of 70,000 to 115,000 CCF, depending on mortality 560

assumptions (scenarios 3 to 6). Nevertheless, these harvest levels would allow the live sawtimber 561

inventory amounts to increase to 6 million CCF in approximately 60 years and return to the level 562

needed to support ASQ as identified in the current forest plan (181,000 CCF) within a century 563

(fig. 6). The bottom line is that net growth (gross growth minus mortality) needs exceed harvest 564

to accumulate wood volume in the Black Hills. 565

28

566

Precommercial thinning the small sized ponderosa pine trees can help accelerate the production 567

of sawtimber. Across the Black Hills, ponderosa pine seedling densities exceeding 10,000 per 568

acre after a disturbance (e.g., natural or mechanical) are not extraordinary (Battaglia et al. 2008; 569

Shepperd and Battaglia 2002). Even though tree mortality from wind, snow, and suppression in 570

such stands is substantial, it is inadequate to allow for tree crown differentiation into dominants 571

and intermediates because the growth of such stands often stagnates. In the past, frequent fire 572

was the thinning agent that reduced small tree density and reduced stagnation (Battaglia et al. 573

2008; Brown and Sieg 1996; Brown and Sieg 1999; Brown et al. 2008; Hunter et al. 2007). Both 574

mechanical thinning and prescribed fire are warranted to produce large trees of both commercial 575

and ecological value at a faster rate. Tree thinning does not increase the productivity of a site, 576

which is controlled by climate and soils, but rather distributes the growth to fewer stems. As a 577

result, depending on the frequency of thinnings and the number and juxtaposition of trees left 578

after a thinning, a wide variety of stand structures, tree sizes, and timber volumes can be 579

produced (Graham et al. 2019). 580

581

The importance of tending stands early in their development has been demonstrated by several 582

studies on the Black Hills (Graham et al. 2019; Myers 1958). In 1931, Myers (1958) initiated a 583

thinning study in stagnated stands that were 28, 40, and 55 years old with d.b.h.’s of 1.0 to 5.1 584

inches. In these stands, a substantial increase in diameter and volume growth was reported 585

compared to the unthinned areas (Myers 1958). In 1961, a study was installed on the Black Hills 586

Experimental Forest in 65-year old stands that were stagnated with initial diameters of 2 to 8 587

inches d.b.h. to examine tree growth response under a variety of thinning regimes (Graham et al. 588

29

2019). This long-term study demonstrated that thinning treatments substantially increased 589

diameter sizes and merchantable volumes compared to unthinned forests over the 48 years of the 590

study (Graham et al. 2019). Depending on the density reduction and initial diameters, tree 591

diameters ranged from 9 to 18 inches d.b.h., compared to 8 inches d.b.h. in the unthinned stands. 592

Both studies demonstrate that thinning to the desired stand density early in stand development 593

would yield larger diameter trees and volume outputs much sooner. Furthermore, Graham et al. 594

(2019) noted that several thinnings over the course of the 48-year study to maintain the density 595

treatments did not produce commercial material, indicating that one thinning close to the desired 596

density at rotation is warranted. 597

598

The use of prescribed fire to reduce tree density is also warranted in this fire-adapted ponderosa 599

pine ecosystem. Using prescribed fire would reduce tree densities, reduce surface fuels, and 600

increase nutrient cycling. The reduction of surface fuels would result in less intense wildfires and 601

help keep future tree mortality low. This is especially important due to the MPB epidemic and 602

past high severity wildfires that were not harvested, which created complexes of heavy fuel loads 603

(Keyser et al. 2009; Sieg et al. 2016). 604

605

References Battaglia, M.A.; Smith, F.W.; [et al.]. 2008. Can prescribed fire be used to maintain fuel treatment effectiveness over time in Black Hills ponderosa pine forests? Forest Ecology and Management. 256(12): 2029–2038. Brown, P.M.; Sieg, C.H. 1996. Fire history in interior ponderosa pine communities of the Black Hills, South Dakota, USA. International Journal of Wildland Fire. 6(3): 97–105. Brown, P.M.; Sieg, C.H. 1999. Historical variability in fire at the ponderosa pine—Northern Great Plains prairie ecotone, southeastern Black Hills, South Dakota. Ecoscience. 6(4): 539–547. Brown, P.M.; Wienk, C.L.; [et al.]. 2008. Fire and forest history at Mount Rushmore. Ecological Applications. 18(8): 1984–1999. Choate, G.A.; Spencer, J.S. 1968. Forests in South Dakota. Resource Bull. INT-8. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station. 40 p. Collins, D.C.; Green A.W. 1988. South Dakota’s timber resources. Resource Bull. INT-56. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 28 p. DeBlander, L.T. 2002. Forest resources of the Black Hills National Forest. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 13 p. Freeman, J.F. 2015. Black Hills forestry: a history. Boulder, CO: University Press of Colorado. Graham, Russell T.; Asherin, Lance A.; [et al.]. 2016. Mountain pine beetles: a century of knowledge, control attempts, and impacts central to the Black Hills. Gen. Tech. Rep. RMRS-GTR-353. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 193 p. Graham, Russell T.; Asherin, Lance A.; [et al.]. 2019. Differing ponderosa pine forest structures, their growth and yield, and mountain pine beetle impacts: growing stock levels in the Black Hills. RMRS- GTR-393. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 102 p. Hunter, M.E.; Shepperd, W.D.; [et al]. 2007. A comprehensive guide to fuels treatment practices for ponderosa pine in the Black Hills, Colorado Front Range, and Southwest. Gen. Tech. Rep.

RMRS-GTR-198. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 93 p. Keyser, T.L.; Smith, F.W.; [et al.]. 2009. Short-term impact of post-fire salvage logging on regeneration, hazardous fuel accumulation, and understory development in ponderosa pine forests of the Black Hills, SD, USA. International Journal of Wildland Fire. 18(4): 451–458. Meyer, Walter H. 1938. Yield of even-aged stands of ponderosa pine. Tech. Bull. 630. Washington, DC: U.S. Department of Agriculture. 60 p. Myers, C.A. 1958. Thinning improves development of young stands of ponderosa pine in the Black Hills. Journal of Forestry. 56: 656–659. Shepperd, Wayne D.; Battaglia, Michael A. 2002. Ecology, silviculture, and management of Black Hills ponderosa pine. Gen. Tech. Rep. RMRS-GTR-97. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 112 p. Sieg, Carolyn; Allen, Kurt; [et al.]. 2016. Forest fuels and predicted fire behavior in the first 5 years after a bark beetle outbreak with and without timber harvest (Project INT-EM-F-11-04). Chapter 12. Gen. Tech. Rep. SRS-213. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 7 p. USDA Forest Service, Forest Inventory and Analysis Program, Nov 2018. Forest Inventory EVALIDator Desktop Version 1.7.2.00. St. Paul, MN: U.S. Department of Agriculture, Forest Service, Northern Research Station. USDA Forest Service, Forest Inventory and Analysis Program, Tue Nov 26 2019 10:32:35 AM. Forest Inventory EVALIDator Desktop Version 1.7.2.00. St. Paul, MN: U.S. Department of Agriculture, Forest Service, Northern Research Station. U.S. Department of Agriculture, Forest Service [USDA FS]. 2005. Black Hills National Forest: phase II amendment. Custer, SD: Black Hills National Forest. 19 p. van Mantgem, P.J.; Stephenson, N.L.; [et al.]. 2009. Widespread increase of tree mortality rates in the western United States. Science. 323(5913): 521-524. Walters, B.F.; Woodall, C.W.; [et al.]. 2013. Forests of the Black Hills National Forest 2011. Resource Bull. NRS-83. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 36 p.

Tables Table 1.—Merchantable volume of ponderosa pine trees (5 inches d.b.h. and greater), in CCF, on suitable timberland of the Black Hills National Forest. See figure 5 for a description of gross growth as described by FIA.

Date Average annual volume (CCF) Standing

live inventory

(CCF)

Average annual as a % of inventory

Gross growth Mortality

Net growth Harvest

Net change

Gross growth Mortality

Net growth Harvest

Net change

a1962 213,010 12,180 200,830 109,780 91,050 7,810,000 2.73% 0.16% 2.57% 1.41% 1.17% b1984 339,540 34,910 301,660 199,540 102,120 13,449,000 2.52% 0.26% 2.24% 1.48% 0.78% c1999 380,000 40,000 340,000 204,628 135,372 15,353,000 2.48% 0.26% 2.21% 1.33% 0.88% d2011 358,170 140,460 217,710 246,630 -28,920 13,477,960 2.66% 1.04% 1.62% 1.83% -0.21% d2017 247,768 246,122 1,646 261,721 -260,075 9,050,031 2.74% 2.72% 0.02% 2.89% -2.87% d2019 185,049 244,703 -59,654 183,592 -244,804 7,958,314 2.33% 3.07% -0.75% 2.31% -3.08%

aEstimates are for softwoods on timberlands within the Black Hills and Custer National Forest portions of South Dakota only. Softwoods include ponderosa pine and white spruce (Choate and Spencer1968). bEstimates are for softwoods on timberlands within the Black Hills and Custer National Forest portions of South Dakota only. Softwoods include ponderosa pine and white spruce. It was not clear if timberlands included lands withdrawn by statute or administrative regulation (Collins and Green 1998). cEstimates are for ponderosa pine on forest land within the Black Hills National Forest including South Dakota and Wyoming. These estimates included values from all forestlands administered by the Black Hills National Forest, including reserved lands, which make up 1% of the total land base. In addition, the report does not indicate if all lands are timber lands (DeBlander 2002). dEstimates are for ponderosa pine on timberlands within the Black Hills National Forest including South Dakota and Wyoming. The 2017 values are from the 130 plots sampled. The 2019 values are from 438 plots, which include the 2017 plots. (USDA 2018, 2019) Table 2.—Merchantable sawtimber volume (9 inches d.b.h. and greater, 7-inch top, and 1-foot stump) in CCF on timberland in the Black Hills National Foresta.

Date Average annual volume (CCF) Standing

live inventory

(CCF)

Average annual as a % of inventory

Gross growth Mortality

Net growth Harvest

Net change

Gross growth Mortality

Net growth Harvest

Net change

2017 215,371 171,156 44,215 206,411 -162,196 6,893,367 3.12% 2.48% 0.64% 2.99% -2.35% 2019 150,694 178,409 -27,715 153,534 -182,558 5,995,428 2.51% 2.98% -0.46% 2.56% -3.04%

aStandard errors for the 2019 sawtimber means:

• Average annual growth: 150,694 CCF ± 8.0% • Average annual mortality: 178,409 CCF ± 22.4% • Inventory volume: 5,995,428 CCF ± 5.5%

APPENDIX Scenario 1: This scenario illustrates the continued annual harvest of 153,534 CCF per acre per year of sawtimber from timberlands (suitable land base) that occurred in 2019 into the future. The annual mortality rate of 2.98% from 2019 was used, and as in all scenarios, the sawtimber growth rate of 2.5% was used (table 2, fig. 6).

Year Date Net

volume Gross

growth Annual

mortality Net

growth Harvest Mortality Growth CCF CCF CCF CCF CCF Percent Percent

1 2019 5,995,428 150,694 178,409 -27,715 153,534 2.975751 2.513482 2 2020 5,814,179 146,138 173,015 -26,877 153,534 2.975751 2.513482 3 2021 5,633,768 141,604 167,647 -26,043 153,534 2.975751 2.513482 4 2022 5,454,191 137,090 162,303 -25,213 153,534 2.975751 2.513482 5 2023 5,275,444 132,597 156,984 -24,387 153,534 2.975751 2.513482 6 2024 5,097,523 128,125 151,690 -23,564 153,534 2.975751 2.513482 7 2025 4,920,425 123,674 146,420 -22,746 153,534 2.975751 2.513482 8 2026 4,744,145 119,243 141,174 -21,931 153,534 2.975751 2.513482 9 2027 4,568,681 114,833 135,953 -21,120 153,534 2.975751 2.513482

10 2028 4,394,027 110,443 130,755 -20,312 153,534 2.975751 2.513482 11 2029 4,220,181 106,073 125,582 -19,509 153,534 2.975751 2.513482 12 2030 4,047,138 101,724 120,433 -18,709 153,534 2.975751 2.513482 13 2031 3,874,896 97,395 115,307 -17,912 153,534 2.975751 2.513482 14 2032 3,703,449 93,086 110,205 -17,120 153,534 2.975751 2.513482 15 2033 3,532,795 88,796 105,127 -16,331 153,534 2.975751 2.513482 16 2034 3,362,930 84,527 100,072 -15,546 153,534 2.975751 2.513482 17 2035 3,193,850 80,277 95,041 -14,764 153,534 2.975751 2.513482 18 2036 3,025,552 76,047 90,033 -13,986 153,534 2.975751 2.513482 19 2037 2,858,032 71,836 85,048 -13,212 153,534 2.975751 2.513482 20 2038 2,691,286 67,645 80,086 -12,441 153,534 2.975751 2.513482 21 2039 2,525,311 63,473 75,147 -11,674 153,534 2.975751 2.513482 22 2040 2,360,104 59,321 70,231 -10,910 153,534 2.975751 2.513482 23 2041 2,195,660 55,188 65,337 -10,150 153,534 2.975751 2.513482 24 2042 2,031,976 51,073 60,467 -9,393 153,534 2.975751 2.513482 25 2043 1,869,049 46,978 55,618 -8,640 153,534 2.975751 2.513482 26 2044 1,706,875 42,902 50,792 -7,890 153,534 2.975751 2.513482 27 2045 1,545,450 38,845 45,989 -7,144 153,534 2.975751 2.513482 28 2046 1,384,772 34,806 41,207 -6,401 153,534 2.975751 2.513482 29 2047 1,224,837 30,786 36,448 -5,662 153,534 2.975751 2.513482 30 2048 1,065,641 26,785 31,711 -4,926 153,534 2.975751 2.513482

31 2049 907,181 22,802 26,995 -4,194 153,534 2.975751 2.513482 32 2050 749,453 18,837 22,302 -3,464 153,534 2.975751 2.513482 33 2051 592,454 14,891 17,630 -2,739 153,534 2.975751 2.513482 34 2052 436,182 10,963 12,980 -2,016 153,534 2.975751 2.513482 35 2053 280,631 7,054 8,351 -1,297 153,534 2.975751 2.513482 36 2054 125,800 3,162 3,743 -582 153,534 2.975751 2.513482

Scenario 2: This scenario illustrates the amount of standing live volume required to sustain a harvest level of 181,000 CCF per year (Forest Plan ASQ) from timberland. The scenario assumes a mortality rate of 1.04% and a 2.5% growth rate.

Year Date Net

volume Gross

growth Annual

mortality Net

growth Harvest Mortality Growth CCF CCF CCF CCF CCF Percent Percent

1 2019 12,300,000 309,158 127,764 181,394 181,000 1.038733 2.513482 2 2020 12,300,394 309,168 127,768 181,400 181,000 1.038733 2.513482 3 2021 12,300,794 309,178 127,772 181,406 181,000 1.038733 2.513482 4 2022 12,301,200 309,188 127,777 181,412 181,000 1.038733 2.513482 5 2023 12,301,612 309,199 127,781 181,418 181,000 1.038733 2.513482 6 2024 12,302,030 309,209 127,785 181,424 181,000 1.038733 2.513482 7 2025 12,302,454 309,220 127,790 181,430 181,000 1.038733 2.513482 8 2026 12,302,884 309,231 127,794 181,437 181,000 1.038733 2.513482 9 2027 12,303,321 309,242 127,799 181,443 181,000 1.038733 2.513482

10 2028 12,303,764 309,253 127,803 181,450 181,000 1.038733 2.513482 11 2029 12,304,213 309,264 127,808 181,456 181,000 1.038733 2.513482 12 2030 12,304,670 309,276 127,813 181,463 181,000 1.038733 2.513482 13 2031 12,305,133 309,287 127,817 181,470 181,000 1.038733 2.513482 14 2032 12,305,602 309,299 127,822 181,477 181,000 1.038733 2.513482 15 2033 12,306,079 309,311 127,827 181,484 181,000 1.038733 2.513482 16 2034 12,306,563 309,323 127,832 181,491 181,000 1.038733 2.513482 17 2035 12,307,054 309,336 127,837 181,498 181,000 1.038733 2.513482 18 2036 12,307,552 309,348 127,843 181,505 181,000 1.038733 2.513482 19 2037 12,308,057 309,361 127,848 181,513 181,000 1.038733 2.513482 20 2038 12,308,570 309,374 127,853 181,521 181,000 1.038733 2.513482 21 2039 12,309,091 309,387 127,859 181,528 181,000 1.038733 2.513482 22 2040 12,309,619 309,400 127,864 181,536 181,000 1.038733 2.513482 23 2041 12,310,155 309,414 127,870 181,544 181,000 1.038733 2.513482 24 2042 12,310,699 309,427 127,875 181,552 181,000 1.038733 2.513482 25 2043 12,311,251 309,441 127,881 181,560 181,000 1.038733 2.513482 26 2044 12,311,811 309,455 127,887 181,568 181,000 1.038733 2.513482 27 2045 12,312,379 309,469 127,893 181,577 181,000 1.038733 2.513482 28 2046 12,312,956 309,484 127,899 181,585 181,000 1.038733 2.513482 29 2047 12,313,541 309,499 127,905 181,594 181,000 1.038733 2.513482 30 2048 12,314,135 309,514 127,911 181,603 181,000 1.038733 2.513482 31 2049 12,314,737 309,529 127,917 181,611 181,000 1.038733 2.513482 32 2050 12,315,349 309,544 127,924 181,620 181,000 1.038733 2.513482 33 2051 12,315,969 309,560 127,930 181,630 181,000 1.038733 2.513482 34 2052 12,316,599 309,575 127,937 181,639 181,000 1.038733 2.513482 35 2053 12,317,238 309,592 127,943 181,648 181,000 1.038733 2.513482

36 2054 12,317,886 309,608 127,950 181,658 181,000 1.038733 2.513482 37 2055 12,318,544 309,624 127,957 181,668 181,000 1.038733 2.513482 38 2056 12,319,212 309,641 127,964 181,677 181,000 1.038733 2.513482 39 2057 12,319,889 309,658 127,971 181,687 181,000 1.038733 2.513482 40 2058 12,320,577 309,675 127,978 181,698 181,000 1.038733 2.513482 41 2059 12,321,274 309,693 127,985 181,708 181,000 1.038733 2.513482 42 2060 12,321,982 309,711 127,992 181,718 181,000 1.038733 2.513482 43 2061 12,322,700 309,729 128,000 181,729 181,000 1.038733 2.513482 44 2062 12,323,429 309,747 128,008 181,740 181,000 1.038733 2.513482 45 2063 12,324,169 309,766 128,015 181,751 181,000 1.038733 2.513482 46 2064 12,324,919 309,785 128,023 181,762 181,000 1.038733 2.513482

Scenario 3: This scenario illustrates reducing harvest volume from 153,534 CCF that occurred in 2019 to 125,000 CCF in 2020 and continuing in a linear fashion to decrease the harvest volume to 85,000 CCF per year over the next 10 years (2030) (fig. 13). Growth rates remained constant at 2.5%, but mortality rates varied. Mortality rates were predicted to decrease linearly from 2.98% to 1.04% by 2028, reflecting what might occur as the MPB epidemic subsides (fig. 14). Also reflecting what occurred historically between MPB epidemics (fig. 1), the scenario decreased the mortality rate to 0.26% by 2034 and increased the mortality rate to 1.04% in 2048.

Year Date Net

Volume Gross

Growth Annual

mortality Net

Growth Harvest Mortality Growth CCF CCF CCF CCF CCF Percent Percent

1 2019 5,995,428 150,694 178,409 -27,715 153,534 2.975751 2.513482 2 2020 5,814,179 146,138 161,753 -15,615 125,000 2.782049 2.513482 3 2021 5,673,564 142,604 146,852 -4,248 120,000 2.588347 2.513482 4 2022 5,549,317 139,481 132,886 6,595 115,000 2.394645 2.513482 5 2023 5,440,911 136,756 119,751 17,005 110,000 2.200943 2.513482 6 2024 5,347,916 134,419 107,346 27,073 105,000 2.007241 2.513482 7 2025 5,269,990 132,460 95,573 36,887 100,000 1.813539 2.513482 8 2026 5,206,877 130,874 84,343 46,531 95,000 1.619837 2.513482 9 2027 5,158,408 129,656 73,566 56,090 90,000 1.426135 2.513482

10 2028 5,124,498 128,803 63,156 65,647 85,000 1.232433 2.513482 11 2029 5,105,145 128,317 53,029 75,288 85,000 1.038731 2.513482 12 2030 5,095,433 128,073 52,928 75,145 85,000 1.038733 2.513482 13 2031 5,085,578 127,825 49,623 78,203 85,000 0.975751 2.513482 14 2032 5,078,781 127,654 49,556 78,098 85,000 0.975751 2.513482 15 2033 5,071,879 127,481 49,489 77,992 85,000 0.975751 2.513482 16 2034 5,064,870 127,305 13,194 114,111 85,000 0.260501 2.513482 17 2035 5,093,981 128,036 13,270 114,766 85,000 0.260501 2.513482 18 2036 5,123,747 128,784 13,347 115,437 85,000 0.260501 2.513482 19 2037 5,154,184 129,549 13,427 116,123 85,000 0.260501 2.513482 20 2038 5,185,307 130,332 13,508 116,824 85,000 0.260501 2.513482 21 2039 5,217,131 131,132 13,591 117,541 85,000 0.260501 2.513482 22 2040 5,249,672 131,950 13,675 118,274 85,000 0.260501 2.513482 23 2041 5,282,946 132,786 13,762 119,024 85,000 0.260501 2.513482 24 2042 5,316,970 133,641 13,851 119,790 85,000 0.260501 2.513482 25 2043 5,351,760 134,516 13,941 120,574 85,000 0.260501 2.513482 26 2044 5,387,335 135,410 14,034 121,376 85,000 0.260501 2.513482 27 2045 5,423,710 136,324 14,129 122,195 85,000 0.260501 2.513482 28 2046 5,460,905 137,259 14,226 123,033 85,000 0.260501 2.513482 29 2047 5,498,939 138,215 14,325 123,890 85,000 0.260501 2.513482 30 2048 5,537,829 139,192 57,523 81,669 85,000 1.038733 2.513482 31 2049 5,534,498 139,109 57,489 81,620 85,000 1.038733 2.513482

32 2050 5,531,118 139,024 57,454 81,570 85,000 1.038733 2.513482 33 2051 5,527,688 138,937 57,418 81,520 85,000 1.038733 2.513482 34 2052 5,524,207 138,850 57,382 81,468 85,000 1.038733 2.513482 35 2053 5,520,675 138,761 57,345 81,416 85,000 1.038733 2.513482 36 2054 5,517,092 138,671 57,308 81,363 85,000 1.038733 2.513482 37 2055 5,513,455 138,580 57,270 81,310 85,000 1.038733 2.513482 38 2056 5,509,764 138,487 57,232 81,255 85,000 1.038733 2.513482 39 2057 5,506,020 138,393 57,193 81,200 85,000 1.038733 2.513482 40 2058 5,502,220 138,297 57,153 81,144 85,000 1.038733 2.513482 41 2059 5,498,363 138,200 57,113 81,087 85,000 1.038733 2.513482 42 2060 5,494,451 138,102 57,073 81,029 85,000 1.038733 2.513482 43 2061 5,490,480 138,002 57,031 80,971 85,000 1.038733 2.513482 44 2062 5,486,451 137,901 56,990 80,911 85,000 1.038733 2.513482 45 2063 5,482,362 137,798 56,947 80,851 85,000 1.038733 2.513482 46 2064 5,478,213 137,694 56,904 80,790 85,000 1.038733 2.513482

Scenario 4: This scenario illustrates reducing the harvest from 153,534 CCF (2019) to 125,000 CCF per year in 2020 and to 75,000 CCF in a linear fashion to year 2030 when it remains constant (fig. 13.). Growth rates remained constant at 2.5%, however mortality rates decreased linearly from 2.98% to 1.04% by 2030 and remained at that level (fig. 14). These changes in mortality rates would reflect the long-term trends observed in the Black Hills as discussed earlier when MPB were endemic and weather and wildfire were determinants of mortality.

Year Date Net

volume Gross

growth Annual

mortality Net

growth Harvest Mortality Growth CCF CCF CCF CCF CCF Percent Percent

1 2019 5,995,428 150,694 178,409 -27,715 153,534 2.975751 2.513482 2 2020 5,814,179 146,138 161,753 -15,615 125,000 2.782049 2.513482 3 2021 5,673,564 142,604 146,852 -4,248 120,000 2.588347 2.513482 4 2022 5,549,317 139,481 132,886 6,595 115,000 2.394645 2.513482 5 2023 5,440,911 136,756 119,751 17,005 110,000 2.200943 2.513482 6 2024 5,347,916 134,419 107,346 27,073 105,000 2.007241 2.513482 7 2025 5,269,990 132,460 95,573 36,887 100,000 1.813539 2.513482 8 2026 5,206,877 130,874 84,343 46,531 95,000 1.619837 2.513482 9 2027 5,158,408 129,656 73,566 56,090 90,000 1.426135 2.513482

10 2028 5,124,498 128,803 63,156 65,647 85,000 1.232433 2.513482 11 2029 5,105,145 128,317 53,029 75,288 80,000 1.038733 2.513482 12 2030 5,100,433 128,198 52,980 75,219 75,000 1.038733 2.513482 13 2031 5,100,652 128,204 52,982 75,222 75,000 1.038733 2.513482 14 2032 5,100,873 128,210 52,984 75,225 75,000 1.038733 2.513482 15 2033 5,101,098 128,215 52,987 75,228 75,000 1.038733 2.513482 16 2034 5,101,327 128,221 52,989 75,232 75,000 1.038733 2.513482 17 2035 5,101,559 128,227 52,992 75,235 75,000 1.038733 2.513482 18 2036 5,101,794 128,233 52,994 75,239 75,000 1.038733 2.513482 19 2037 5,102,032 128,239 52,996 75,242 75,000 1.038733 2.513482 20 2038 5,102,275 128,245 52,999 75,246 75,000 1.038733 2.513482 21 2039 5,102,520 128,251 53,002 75,249 75,000 1.038733 2.513482 22 2040 5,102,770 128,257 53,004 75,253 75,000 1.038733 2.513482 23 2041 5,103,023 128,264 53,007 75,257 75,000 1.038733 2.513482 24 2042 5,103,279 128,270 53,009 75,261 75,000 1.038733 2.513482 25 2043 5,103,540 128,277 53,012 75,264 75,000 1.038733 2.513482 26 2044 5,103,804 128,283 53,015 75,268 75,000 1.038733 2.513482 27 2045 5,104,073 128,290 53,018 75,272 75,000 1.038733 2.513482 28 2046 5,104,345 128,297 53,021 75,276 75,000 1.038733 2.513482 29 2047 5,104,621 128,304 53,023 75,280 75,000 1.038733 2.513482 30 2048 5,104,902 128,311 53,026 75,284 75,000 1.038733 2.513482 31 2049 5,105,186 128,318 53,029 75,289 75,000 1.038733 2.513482 32 2050 5,105,475 128,325 53,032 75,293 75,000 1.038733 2.513482

33 2051 5,105,768 128,333 53,035 75,297 75,000 1.038733 2.513482 34 2052 5,106,065 128,340 53,038 75,302 75,000 1.038733 2.513482 35 2053 5,106,367 128,348 53,042 75,306 75,000 1.038733 2.513482 36 2054 5,106,673 128,355 53,045 75,311 75,000 1.038733 2.513482 37 2055 5,106,983 128,363 53,048 75,315 75,000 1.038733 2.513482 38 2056 5,107,298 128,371 53,051 75,320 75,000 1.038733 2.513482 39 2057 5,107,618 128,379 53,055 75,325 75,000 1.038733 2.513482 40 2058 5,107,943 128,387 53,058 75,329 75,000 1.038733 2.513482 41 2059 5,108,272 128,395 53,061 75,334 75,000 1.038733 2.513482 42 2060 5,108,606 128,404 53,065 75,339 75,000 1.038733 2.513482 43 2061 5,108,946 128,412 53,068 75,344 75,000 1.038733 2.513482 44 2062 5,109,290 128,421 53,072 75,349 75,000 1.038733 2.513482 45 2063 5,109,639 128,430 53,075 75,354 75,000 1.038733 2.513482 46 2064 5,109,993 128,439 53,079 75,360 75,000 1.038733 2.513482

Scenario 5: This scenario illustrates reducing the harvest from 153,534 CCF (2019) to 125,000 CCF per year in 2020. From 2020 through 2025 the harvest was linearly reduced to 70,000 CCF per year (fig. 12). Growth rates remained at 2.5%, however mortality rates decreased from 2.98% in 2020 to 1.04% by 2030 (fig. 14), reflecting the historical norm.

Year Date Net

volume Gross

growth Annual

mortality Net

growth Harvest Mortality Growth CCF CCF CCF CCF CCF Percent Percent

1 2019 5,995,428 150,694 178,409 -27,715 153,534 2.975751 2.513482 2 2020 5,814,179 146,138 161,753 -15,615 120,000 2.782049 2.513482 3 2021 5,678,564 142,730 146,981 -4,251 90,000 2.588347 2.513482 4 2022 5,584,313 140,361 133,724 6,636 85,000 2.394645 2.513482 5 2023 5,505,949 138,391 121,183 17,208 80,000 2.200943 2.513482 6 2024 5,443,158 136,813 109,257 27,556 75,000 2.007241 2.513482 7 2025 5,395,713 135,620 97,853 37,767 70,000 1.813539 2.513482 8 2026 5,363,480 134,810 86,880 47,930 70,000 1.619837 2.513482 9 2027 5,341,410 134,255 76,176 58,080 70,000 1.426135 2.513482

10 2028 5,329,490 133,956 65,682 68,273 70,000 1.232433 2.513482 11 2029 5,327,764 133,912 55,341 78,571 70,000 1.038733 2.513482 12 2030 5,336,335 134,128 55,430 78,698 70,000 1.038733 2.513482 13 2031 5,345,032 134,346 55,521 78,826 70,000 1.038733 2.513482 14 2032 5,353,858 134,568 55,612 78,956 70,000 1.038733 2.513482 15 2033 5,362,814 134,793 55,705 79,088 70,000 1.038733 2.513482 16 2034 5,371,902 135,022 55,800 79,222 70,000 1.038733 2.513482 17 2035 5,381,124 135,254 55,896 79,358 70,000 1.038733 2.513482 18 2036 5,390,482 135,489 55,993 79,496 70,000 1.038733 2.513482 19 2037 5,399,978 135,727 56,091 79,636 70,000 1.038733 2.513482 20 2038 5,409,614 135,970 56,191 79,778 70,000 1.038733 2.513482 21 2039 5,419,393 136,215 56,293 79,922 70,000 1.038733 2.513482 22 2040 5,429,315 136,465 56,396 80,069 70,000 1.038733 2.513482 23 2041 5,439,384 136,718 56,501 80,217 70,000 1.038733 2.513482 24 2042 5,449,601 136,975 56,607 80,368 70,000 1.038733 2.513482 25 2043 5,459,969 137,235 56,714 80,521 70,000 1.038733 2.513482 26 2044 5,470,490 137,500 56,824 80,676 70,000 1.038733 2.513482 27 2045 5,481,166 137,768 56,935 80,833 70,000 1.038733 2.513482 28 2046 5,491,999 138,040 57,047 80,993 70,000 1.038733 2.513482 29 2047 5,502,992 138,317 57,161 81,155 70,000 1.038733 2.513482 30 2048 5,514,148 138,597 57,277 81,320 70,000 1.038733 2.513482 31 2049 5,525,468 138,882 57,395 81,487 70,000 1.038733 2.513482 32 2050 5,536,954 139,170 57,514 81,656 70,000 1.038733 2.513482 33 2051 5,548,611 139,463 57,635 81,828 70,000 1.038733 2.513482

34 2052 5,560,439 139,761 57,758 82,003 70,000 1.038733 2.513482 35 2053 5,572,441 140,062 57,883 82,180 70,000 1.038733 2.513482 36 2054 5,584,621 140,368 58,009 82,359 70,000 1.038733 2.513482 37 2055 5,596,980 140,679 58,138 82,541 70,000 1.038733 2.513482 38 2056 5,609,521 140,994 58,268 82,726 70,000 1.038733 2.513482 39 2057 5,622,248 141,314 58,400 82,914 70,000 1.038733 2.513482 40 2058 5,635,162 141,639 58,534 83,104 70,000 1.038733 2.513482 41 2059 5,648,266 141,968 58,670 83,298 70,000 1.038733 2.513482 42 2060 5,661,564 142,302 58,809 83,494 70,000 1.038733 2.513482 43 2061 5,675,058 142,642 58,949 83,693 70,000 1.038733 2.513482 44 2062 5,688,751 142,986 59,091 83,895 70,000 1.038733 2.513482 45 2063 5,702,645 143,335 59,235 84,100 70,000 1.038733 2.513482 46 2064 5,716,745 143,689 59,382 84,308 70,000 1.038733 2.513482

Scenario 6: This scenario illustrates the potential harvest if mortality decreases from 2.98 to 2.43% in 2020 and to 0.26% by 2028 (fig. 14). This historically low mortality rate did occur when few wildfires burned and MPB activity was minimal (figs. 1, 2). Growth rates were maintained at 2.5%

Year Date Net

volume Gross

growth Annual

mortality Net

growth Harvest Mortality Growth CCF CCF CCF CCF CCF Percent Percent

1 2019 5,995,428 150,694 178,409 -27,715 153,534 2.975751 2.513482 2 2020 5,814,179 146,138 141,436 4,703 125,000 2.432601 2.513482 3 2021 5,693,882 143,115 123,046 20,068 120,000 2.161025 2.513482 4 2022 5,593,950 140,603 105,695 34,908 115,000 1.889450 2.513482 5 2023 5,513,858 138,590 89,207 49,382 115,000 1.617875 2.513482 6 2024 5,448,241 136,941 73,350 63,591 115,000 1.346300 2.513482 7 2025 5,396,832 135,648 58,001 77,647 115,000 1.074725 2.513482 8 2026 5,359,479 134,710 43,045 91,665 115,000 0.803150 2.513482 9 2027 5,336,144 134,123 28,366 105,757 115,000 0.531575 2.513482

10 2028 5,326,901 133,891 13,877 120,014 115,000 0.260501 2.513482 11 2029 5,331,915 134,017 13,890 120,127 115,000 0.260501 2.513482 12 2030 5,337,042 134,146 13,903 120,243 115,000 0.260501 2.513482 13 2031 5,342,285 134,277 13,917 120,361 115,000 0.260501 2.513482 14 2032 5,347,646 134,412 13,931 120,481 115,000 0.260501 2.513482 15 2033 5,353,127 134,550 13,945 120,605 115,000 0.260501 2.513482 16 2034 5,358,732 134,691 13,960 120,731 115,000 0.260501 2.513482 17 2035 5,364,463 134,835 13,974 120,860 115,000 0.260501 2.513482 18 2036 5,370,324 134,982 13,990 120,992 115,000 0.260501 2.513482 19 2037 5,376,316 135,133 14,005 121,127 115,000 0.260501 2.513482 20 2038 5,382,443 135,287 14,021 121,265 115,000 0.260501 2.513482 21 2039 5,388,709 135,444 14,038 121,407 115,000 0.260501 2.513482 22 2040 5,395,115 135,605 14,054 121,551 115,000 0.260501 2.513482 23 2041 5,401,666 135,770 14,071 121,699 115,000 0.260501 2.513482 24 2042 5,408,365 135,938 14,089 121,849 115,000 0.260501 2.513482 25 2043 5,415,214 136,110 14,107 122,004 115,000 0.260501 2.513482 26 2044 5,422,218 136,286 14,125 122,162 115,000 0.260501 2.513482 27 2045 5,429,380 136,466 14,144 122,323 115,000 0.260501 2.513482 28 2046 5,436,702 136,651 14,163 122,488 115,000 0.260501 2.513482 29 2047 5,444,190 136,839 14,182 122,657 115,000 0.260501 2.513482 30 2048 5,451,847 137,031 14,202 122,829 115,000 0.260501 2.513482 31 2049 5,459,676 137,228 14,222 123,005 115,000 0.260501 2.513482 32 2050 5,467,681 137,429 14,243 123,186 115,000 0.260501 2.513482 33 2051 5,475,867 137,635 14,265 123,370 115,000 0.260501 2.513482

34 2052 5,484,238 137,845 14,286 123,559 115,000 0.260501 2.513482 35 2053 5,492,796 138,060 14,309 123,752 115,000 0.260501 2.513482 36 2054 5,501,548 138,280 14,332 123,949 115,000 0.260501 2.513482 37 2055 5,510,497 138,505 14,355 124,150 115,000 0.260501 2.513482 38 2056 5,519,647 138,735 14,379 124,357 115,000 0.260501 2.513482 39 2057 5,529,004 138,971 14,403 124,567 115,000 0.260501 2.513482 40 2058 5,538,571 139,211 14,428 124,783 115,000 0.260501 2.513482 41 2059 5,548,354 139,457 14,454 125,003 115,000 0.260501 2.513482 42 2060 5,558,358 139,708 14,480 125,229 115,000 0.260501 2.513482 43 2061 5,568,586 139,965 14,506 125,459 115,000 0.260501 2.513482 44 2062 5,579,046 140,228 14,533 125,695 115,000 0.260501 2.513482 45 2063 5,589,740 140,497 14,561 125,936 115,000 0.260501 2.513482 46 2064 5,600,676 140,772 14,590 126,182 115,000 0.260501 2.513482

Figure captions Figure 1. Within the forests of the Black Hills, there has been a continuous endemic and several epidemics of mountain pine beetles (MPB) over the last 129 years. There is an uncertainty about the exact number of trees killed but the above graph provides estimates from descriptions and values provided by a variety of sources (see Graham et al. 2016, fig. 31). From 1985 through 2012, 7,578,000 trees were estimated to have been killed (see fig. 2). Figure 2. The most recent (e.g., 1998) MPB epidemic started with some isolated trees being killed near the BHNF northeastern border (e.g., Sturgis, SD). From there the epidemic spread through the central portion of the Black Hills and from 2010 through 2016, an additional 130,700 acres were infested. Infestation does not connote 100% mortality. As a result from 1985 thriugh 2016 over 410,000 acres were impacted by MPB. Notably, the MPB infestation was less in Wyoming than in South Dakota (see Graham et al. 2016, figs. 65–69, for details on the extent and impact of MPB in the Black Hills). In addition to MPB wildfires burned large portions of the Black Hills from 1988 through 2016. Figure 3. The 438 Northern FIA plots (one plot ≈ 3,000 acres) were randomly distributed throughout the Black Hills National Forest in South Dakota and Wyoming. Data were collected in 2017, 2018, and 2019. These data and inferences derived from them are applicable for Forestwide estimates. Figure 4. Components of gross growth from the previous measurement to the 2019 FIA data categorized by trees 5 inches and greater in d.b.h. and 9 inches and greater in d.b.h.. Gross growth includes trees growing into the size class, the growth on these trees, the growth on trees that died, and growth on trees that were harvested. Total gross growth also includes the growth on trees removed from the suitable land base because of land use changes and trees that returned to the suitable land base through land use changes. These values are not shown on the graph since the amounts were negligible. Gross growth components were not described for the 1962, 1984, 1999, and 2011 inventories. Figure 5. Historical annual mortality rates based on standing inventory for the BHNF. Mortality rates for 1962 (Choate 1968) and 1984 (Collins and Green 1988) are for trees greater than 5 inches d.b.h. and only for the South Dakota portion of the BHNF. Mortality rates for 1999 (DeBlander 2002), 2011 (Walters et al. 2013), 2017 (USDA FIA 2017), and 2019 (USDA FIA 2019) include both Wyoming and South Dakota portions of the BHNF. Figure 6. Trends from 1962 through 2019 for gross growth (tables 1, 2; fig. 5), mortality (tables 1, 2; fig. 6), net growth, harvest, and standing inventory (tables 1, 2) for ponderosa pine trees greater than 5 inches d.b.h. Note, estimates from 1962 are for softwoods on timberlands within the Black Hills and Custer National Forest portions of South Dakota only. Softwoods include ponderosa pine and white spruce. Estimates from 1984 are for softwoods on timberlands within the Black Hills and Custer National Forest portions of South Dakota only. Softwoods include ponderosa pine and white spruce. It wasn’t clear if timberlands included lands withdrawn by statute or administrative regulation. Estimates from 1999 are for ponderosa pine on forest land within the Black Hills National Forest, including South Dakota and Wyoming. These estimates included values from all forestlands administered by the Black Hills National Forest, including

reserved lands, which make up 1% of the total land base. In addition, the report does not indicate if all lands are timberlands. Estimates from 2011, 2017, and 2019 are for ponderosa pine on timberlands within the Black Hills National Forest, including South Dakota and Wyoming. Figure 7. Mean d.b.h. comparison of trees killed by MPB to the mean d.b.h. of live of ponderosa pine trees within 39 plots followed in the South Dakota portion of the BHNF. The plots were monitored from 1985 through 2012. For example, in one sample, the mean d.b.h. of trees killed by MPB was 20.0 inches (red arrow-Y axis) while the mean d.b.h. of the live trees on the plot was 11.8 inches (X axis). In another plot, the mean d.b.h. of trees being killed by MPB and the d.b.h. mean of live trees on the plot were the same (11.2 inches-black arrow) (in Graham et al. 2016; fig. 74). Figure 8. Per acre gross growth and mortality for ponderosa pine trees 5 inches d.b.h. and greater growing on timberlands on the BHNF. Figure 9. All six sawtimber scenarios are shown. Scenarios 3–6, which are grouped in the center of the graph, are described in figures 11–13, as to differentiate among the curves. Figure 10. Potential harvest volumes for scenarios 3, 4, 5, and 6. Figure 11. Mortality rates used in scenarios 3, 4, 5, and 6. Figure 12. Changes in standing live volume of ponderosa pine sawtimber resource in the Black Hills National Forest under different harvest and mortality rate scenarios.

Figure 1

Figure 1

Figure 3

N

10 miles

South DakotaWyoming

South DakotaWyoming

.12.12

2019 FIA plot locations

Figure 4

Figure 5

Figure 6

Figure 7

5

7

9

11

13

15

17

19

21

5 7 9 11 13 15 17 19

MPB

kill

ed tr

ee d

.b.h

. (in

ches

)

Live tree d.b.h. (inches)

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12