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YQRES-02727; No. of pages: 15; 4C:

Quaternary Research xx (2006) xxx–xxx 1 www.elsevier.com/locate/yqres

2 Late holocene forest dynamics, volcanism, and climate change at whitewing 3 mountain and San Joaquin Ridge, Mono County, , CA, USA ⁎ 4 Constance I. Millar a, , John C. King b, Robert D. Westfall a, Harry A. Alden c, Diane L. Delany a

5 a USDA Forest Service, Sierra Nevada Research Center, Pacific Southwest Research Station, Berkeley, CAOF 94701, USA 6 b Lone Pine Research, Bozeman, MT 59715, USA 7 c Smithsonian Institution, Center for Materials Research and Education, Suitland, MD 20746, USA 8 Received 17 June 2005

9 Abstract

10 Deadwood tree stems scattered above treeline on tephra-covered slopes of Whitewing Mtn (3051 m) and San Joaquin Ridge (3122 m) show 11 evidence of being killed in an eruption from adjacent Glass Creek Vent, Inyo Craters. Using tree-ring methods, we dated deadwood to AD 815– 12 1350, and infer from death dates that the eruption occurred in late summer AD 1350. Based on wood anatomy, we identified deadwood species as 13 Pinus albicaulis, P. monticola, P. lambertiana, P. contorta, P. jeffreyi, and Tsuga mertensiana. Only P. albicaulis grows at these elevations 14 currently; P. lambertiana is not locally native. Using contemporary distributionsED of the species, PRO we modeled paleoclimate during the time of 15 sympatry to be significantly warmer (+3.2°C annual minimum temperature) and slightly drier (−24 mm annual precipitation) than present, 16 resembling values projected for in the next 70–100 yr. 17 © 2006 Published by University of Washington. 18 19 Keywords: Paleoecology; Medieval climate; Late Holocene; Climate change; Long Valley volcanism; Inyo Craters; Forest history; Paleoclimatic modeling; Tree-ring 20 dating

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22 Introduction bance remain poorly understood. Preserved vegetation in the 34 Mammoth Lakes– region provides a 35 23 The last millennium is an important reference period for detailed record of late Holocene climatic, vegetation, and 36 24 evaluating the significance of future climate change and impacts volcanic dynamics. Scattered across the otherwise barren 37 25 ORRECT– 38 on ecosystems. The Medieval period (ca. AD 900 1350) in summits of Whitewing Mtn and San Joaquin Ridge, adjacent 26 particular has been controversial as an analog for future con- to and along the Sierra Nevada crest (Fig. 1), are abundant well- 39 27 ditions (Mann et al., 1999; Esper et al., 2002). In the eastern preserved deadwood tree stems (Fig. 2). The stems are, for the 40 28 Sierra Nevada, late Holocene climate variability (Stine, 1994; elevation, unusually large in diameter and length. The wood is 41 29 Benson et al., 2002), glacial dynamics (Clark and Gillespie, well preserved and in cross-section displays large growth rings. 42 30 1997), volcanism (Sieh and Bursik, 1986), and ecological Many stems are stumpless, while others remain rooted but 43 31 response (Woolfenden,UNC 1996) are well documented. While the buried in tephra. The summits lie directly adjacent to vents of 44 32 outline of centennial scale variability has been drawn for this the Inyo Crater volcanic chain, which has a history of late 45 33 region, interactions of forcing factors and ecological distur- Holocene eruption episodes (Miller, 1984, 1985; Sieh and 46 Bursik, 1986). The presence of dead trees above current treeline 47 suggests that past climates were different from present, while 48 the proximity of the volcanic vents and condition of the dead- 49 ⁎ Corresponding author. USDA Forest Service, Sierra Nevada Research wood suggest that an eruption killed the trees. 50 Center, Pacific Southwest Research Station, P.O. Box 245 Berkeley, CA 94701, 51 USA (street address: West Annex Bldg., 800 Buchanan St., Albany, CA 94710). We undertook this study to evaluate the climatic, ecologic, Fax: +1 510 559 6499. and disturbance history of the deadwood forest on Whitewing 52 E-mail address: [email protected] (C.I. Millar). Mtn and San Joaquin Ridge, specifically, to identify species of 53

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Figure 1. A. Regional mapUNCO of Whitewing Mtn and San Joaquin Ridge, Mono Co., Eastern Sierra Nevada, CA, showing features mentioned in the text. 54 trees that grew there, determine tree ages, delimit timing of the San Joaquin Ridge (3122 m) forms the Sierra Nevada 62 55 Glass Creek eruption, model paleoclimates, and infer causes for hydrologic crest west of Whitewing Mtn, creating a low pass 63 56 the presence and death of the summit forests. at Minaret Summit, 2796 m. Thick deposits of Quaternary 64 tephras dominate all but a few surfaces (Bailey et al., 1976). 65 57 Study area These derive from eruptions of the adjacent Mono Craters and 66 Inyo Craters, a series of magmatic and phreatic eruptive centers 67 58 Location and surficial geology extending from near Mammoth Mtn to Mono Lake (Fig. 1; 68 Wood, 1977). Recent eruptive episodes of vents near White- 69 59 Whitewing Mtn (3051 m) is a distinct, flat-topped peak that wing Mtn occurred 6,000 yr ago, 1250–1400 yr ago, and 550– 70 60 projects eastward from the main crest of the central Sierra 820 yr ago (Miller, 1984, 1985; Sieh and Bursik, 1986). The 71 61 Nevada into the headwaters basin of the Owens River (Fig. 1). most recent eruption of Glass Creek Vent blasted directly onto 72 ARTICLE IN PRESS

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lodgepole pine/western white pine (Pinus monticola) forests 104 grow at 2450–2700 m, and form the lowest of the subalpine 105 types. The subalpine forests grade at lower elevations into 106 lodgepole pine/Jeffrey pine (Pinus jeffreyi) forests, which occur 107 from 2300 to 2600 m, and form extensive forests with 108 continuous canopies. Pinyon pine (P. monophylla) woodlands 109 form the lowest elevation forest, extending down to 1500 m in 110 the western Great Basin. 111 Current and paleo-climate F 112 The contemporary climate of the upper Owens River 113 watershed is montane Mediterranean with long dry summers 114 and cool wet winters. Precipitation occurs primarily in winter 115 from Pacific frontal storms that move eastward depositing snow 116 orographically over the western slope of the Sierra Nevada. 117 Gradients of precipitation and temperature are steep, and the 118 eastern slopes and western Great Basin lie in a rain-shadow. 119 Summer moisture occurs sporadically from Gulf-origin mon- 120 soon influence. SummerPROO temperatures range from warm/ 121 moderate at high elevations to hot east of the crest; atmospheric 122 Figure 2. Deadwood stems on Whitewing Mtn, showing flat summit plateau humidities are low throughout the region. 123 mantled with tephra and scattered large logs. Late Holocene climates have been described from diverse 124 records in the Sierra Nevada and Great Basin (Woolfenden, 125 73 Whitewing Mtn and San Joaquin Ridge, depositing 8 m of 1996; Stine, 1994). The last millennium began with a 450-yr 126 74 tephra on Whitewing Mtn and 1 m on San Joaquin Ridge phaseED that corresponds to the widespread Medieval Climate 127 75 (Miller, 1985). Ages for this eruption range from 530 ± 100 cal Anomaly (MCA), and extended from ca. AD 900–1350 in the 128 76 yr B.P. to 720 ± 60 cal yr B.P., with a minimum tree-ring date of Sierra Nevada. Proxy records indicate this to have been a dry 129 77 AD 1472 (Wood, 1977; Miller, 1984, 1985). Glass Creek tephra and warm period, where lake and river levels declined (Yuan 130 78 overlies deposits dated 659–737 cal yr B.P. from a nearby et al., 2004; Meko et al., 2001; Stine, 1990, 1994), treelines 131 79 phreatic crater on Mammoth Mtn (Sorey et al., 1998). increased (Graumlich, 1993; Graumlich and Lloyd, 1996), and 132 glaciers retreated (Konrad and Clark, 1998). The MCA was 133 80 Current forest types followed by a cool phase coinciding with the northern 134 hemispheric Little Ice Age (LIA), which extended in the Sierra 135 81 Plant communities represent typical eastern Sierra eleva- Nevada from AD 1400 to 1900 (Clark and Gillespie, 1997). 136 82 tional zonation, with local variations in extent. Alpine tundra Closed lake levels remained moderately low, suggesting 137 83 vegetation occurs above 2990 m on San JoaquinRRECT Ridge and decreases in effective precipitation and/or runoff relative to 138 84 Whitewing Mtn. Below this is the whitebark pine (Pinus present (Stine, 1990). Treeline elevations declined (Graumlich 139 85 albicaulis) forest type, which extends from 2700 m to local and Lloyd, 1996; Lloyd and Graumlich, 1997) and the largest 140 86 treeline at 2990 m. The upper limit of the whitebark type is glacial advances since the Pleistocene are recorded (Clark and 141 87 characterized by a zone of stunted krummholz (shrub-like) Gillespie, 1997). The LIA ended ∼ AD 1900; early 20th century 142 88 pines. This grades into a lower zone of upright pines that form proxies record rising temperatures, precipitation increases 143 89 dense clusters and occasionally continuous forest canopies. (Graumlich, 1993) and increasing lake and river levels (Stine, 144 90 Outliers occur above the general treeline in sheltered areas 1990, 1994). 145 91 around rocky outcrops. Locally, these occur near the summits of 92 Whitewing Mtn and SanUNCO Joaquin Ridge. Methods 146 93 Subalpine forest assemblages overlap the whitebark pine 94 type and extend below it. These vary with slope and aspect as a Stem mapping and stem measurements 147 95 consequence of ecological tolerances of the species. At the 96 upper elevations are mixed red fir (Abies magnifica)/lodgepole We mapped deadwood greater than 1 m length and 10 cm 148 97 pine (Pinus contorta ssp. murrayana)/mountain hemlock diameter above local treeline on Whitewing Mtn and San 149 98 (Tsuga mertensiana) forests (2600–2800 m). The extensive Joaquin Ridge between Minaret Summit and Deadman Pass. For 150 99 cover of red fir is unusual in that the primary species range is each deadwood sample, we measured acropetal orientation of 151 100 west of the Sierra Nevada crest at mid-elevations. This situation the main stem axis, largest stem diameter, stem length, and noted 152 101 appears to result from the low Sierran gap of the San Joaquin whether the stem had an attached base (stump). We mapped 153 102 Ridge, which provides access for wet Pacific storms to cross the deadwood by GPS at 17 topographically distinct locations on 154 103 divide, and also serves as a biogeographic corridor. Mixed Whitewing Mtn and 3 locations on San Joaquin Ridge. 155 ARTICLE IN PRESS

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156 Deadwood species identification In addition to deadwood, we collected increment cores from 205 30 live krummholz whitebark pines growing in rocky outcrops 206 157 We cut transverse sections from deadwood on Whitewing below the Whitewing Mtn summit, and dated these with 207 158 Mtn and San Joaquin Ridge and subsampled these for ident- conventional tree-ring techniques. 208 159 ification by wood anatomy. Samples represented all major To compare relative growth conditions of the Whitewing 209 160 deadwood locations, and included a range of sizes and forms trees to other forests growing in the Sierra Nevada and White 210 161 present. Wood samples were prepared for analysis using minor Mtns, we extracted data from 40 long tree-ring chronologies 211 162 modifications of conventional methods (Kellogg et al., 1982). from the ITRDB (2005c), computed mean sensitivity values and 212 163 Samples were identified to generic level using diagnostic keys average ring-width for each, and compared these to Whitewing 213 164 (Kukachka, 1960) and by comparing unknowns with vouchered values. 214 165 material at the Smithsonian Institution's collection, as well as F 166 wood from live trees of candidate species collected locally. Dating the glass creek vent volcanic eruption 215 167 Identification to species level was critical to our assessment, but 168 difficult with the candidates involved. Thus, in addition to Previous efforts to date the most recent eruption from Glass 216 169 standard keys, we used a combination of specific diagnostic Creek Vent relied on radiocarbon assessments of charcoal and 217 170 traits to resolve taxonomy, including presence/absence of resin minimum tree-ring ages, which yielded a wide age range. 218 171 pockets, dimples, crystals in the resin canals, and shape of the ray Because the trees on Whitewing Mtn and San Joaquin Ridge 219 172 cross fields (Kellogg et al., 1982; Miller and Wiedenhoeft, 2003; appear to have been killed by the eruption, their death date 220 173 Wiedenhoeft et al., 2003a, 2003b; IAWA, 2004). Resolution of a should more accurately date the eruption. Scouring winds, 221 174 minimum of six species from Whitewing Mtn (see Results) however, have erodedPROO unknown numbers of outer growth rings 222 175 informed our subsequent methods for dating deadwood and from the samples. We used three independent methods to infer a 223 176 modeling paleoclimates. date for the eruption. First, we searched for deadwood on 224 Whitewing Mtn that was protected from erosion and retained 225 177 Tree-ring dating & analysis the final year's growth; the most recent death date would 226 estimate the eruption date. Second, we used number of sapwood 227 178 Tree-ring samples were prepared for analysis using standard rings toED correct for loss of outer rings from erosion. This 228 179 techniques (Stokes and Smiley, 1968). The Whitewing and San assumes that the number of sapwood rings is relatively constant 229 180 Joaquin Ridge deadwood collection presented challenges for within species at a particular environment. To check this 230 181 dating as it was characterized by multiple species, low mean assumption and obtain species-specific values, we surveyed 231 182 growth sensitivity (a measure of high-frequency variation, Fritts, number of sapwood rings in local live trees. For Pinus 232 183 1976), and relatively short mean ring-series lengths. We modi- albicaulis, we also had a previous sapwood survey from nearby 233 184 fied standard dendrochronological analysis methods (Holmes et Yosemite National Park for comparison (King, J.C., unpub- 234 185 al., 1986; Cook and Kairukstis, 1990) in three ways. First, to lished). We then crossdated sapwood boundaries in the 235 186 improve conventional cross-dating graphical methods, we con- deadwood and added the species-specific mean number of 236 187 verted measurement series into skeleton plot values using a sapwood rings derived from the live tree survey to estimate 237 188 model derived from an inverse curve relationship: death dates. As a third method, we searched for old trees and 238 RRECTdeadwood in locations that were topographically protected from 239 the direct volcanic blast, and that might have survived the 240 Y ¼ 11:0920 þ½ð−11:156Þ=ð0:239=X Þð0:20X − þ 0:70X − t t 3 t 2 eruption. In candidates, we inspected ring widths for evidence 241 of extremely suppressed growth during the Medieval period. 242 þ 1:70Xt − 1 þ 1:20Xt þ 1 þ 0:45Xt þ 2Þ Estimating paleo- and current climates at Whitewing Mtn and 243 189190 where Y represents the skeleton plot value for a given year, Xt is San Joaquin Ridge 244 191 the ring width for a given year, and Xt − 3, Xt − 2, Xt − 1, Xt +1, Xt +2 192 are the ring widths for the preceding 3 yr and following 2 yr. We modeled paleoclimates based on ecological niche theory. 245 193 Next, we obtained six regionalUNCO tree-ring chronologies represen- The six species that we identified from Whitewing Mtn do not 246 194 tative of the candidate species from the International Tree-Ring occur together at present. We reasoned that during the period of 247 195 Data Bank (ITRDB, 2005a). From these we determined optimal sympatry on Whitewing Mtn, the climate must have been 248 196 standardizations for the unknown set (Yamaguchi and Allen, compatible for all the species, i.e., fundamental niche spaces 249 197 1992; Yamaguchi, 1994). Finally, using program CRONOL overlapped (Jackson and Overpeck, 2000). Thus, conditions 250 198 (Cook and Holmes, 1992), we assembled a long reference represented by the intersection of individual climate spaces of 251 199 chronology by combining the tree-ring measurement series of the deadwood species would estimate a potential climate of 252 200 five 1000+ yr high-elevation tree-ring chronologies obtained Whitewing Mtn during the time of the summit assemblage. A 253 201 from ITRDB (ITRDB, 2005b). The unknown samples were similar rationale was used by Arundel (2005). 254 202 combined into a floating chronology that was absolutely cross- We obtained digitized high-resolution species range maps 255 203 dated by correlation and skeleton plot comparison to the from the California Gap Analysis Program (Davis et al., 1998)for 256 204 assembled reference chronology. five of the six deadwood species at Whitewing Mtn (excluding 257 ARTICLE IN PRESS

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258 lodgepole pine because of its low habitat sensitivity), and selected quantile plots, and we concluded that the assumption of normality 284 259 each species present in polygons for the dominant and co- of residuals in DA was not seriously violated. Using DA, we 285 260 dominant, primary through tertiary, cover types in the Sierra identified the area of overlap among the five species (JMP, SAS 286 261 Nevada and eastern Sierra eco-regions. The median size of the Institute, 2004). We classified the analysis by species with the 287 262 polygons was 500 ha and minimum resolution 100 ha, which climatic measures as variables, maximizing multispecies differ- 288 263 allowed for sensitivity in identifying diverse habitat conditions. ences in multivariate climate space. The overlapping climate 289 264 We next downloaded 4 km2 (2.5 arcmin) gridded climate data space was defined by those polygons with a Bayesian 290 265 from PRISM (Daly et al., 1994), extracting layers for annual classification probability greater than 0.09 for all five species. 291 266 minimum and annual maximum temperatures; January and July We then computed mean climatic data from the 4 km2 PRISM 292 267 minimum temperatures; January and July maximum tempera- model for this classified subset, which we interpret as an estimate 293 268 tures; annual precipitation; and January and July precipitation, for of paleoclimate at Whitewing Mtn during theF time of sympatry. 294 269 the period of record, 1971–2000. We chose these variables for To test fit of PRISM data for Whitewing Mtn, we evaluated 295 270 their ecological significance to the species and because they span the root mean square deviation (RMSD) of inferred current 296 271 annual climatic extremes. The PRISM grids were converted to climate values from the 1971 to 2000 instrumental records of the 297 272 polygons and sequentially intersected with each of the species' Bishop, Lee Vining, Bridgeport, and Bodie, California weather 298 273 range polygons, with GIS analyses done in ARC/Info (ESRI, stations (WRCC, 2005). Because RMSDs were large using the 299 274 2002). 4km2 dataset, we sought to improve resolution. Spatial Climate 300 275 To determine the overlap among species, we first subjected the Analysis Service (SCAS, Chris Daly, July 2005) provided us 301 276 merged species-range/PRISM-climate data to discriminant anal- with a new high-resolution dataset (30 arcsec) for the Whitewing 302 277 ysis (DA). DAwas used because it maximizes differences among Mtn/San Joaquin areaPROO for January and July minimum and 303 278 groups (species) and discriminates overlap areas better than other maximum temperatures, respectively, which we used unadjusted 304 279 methods. A test for normality indicated excessive tailing in the in subsequent analysis. 305 280 residuals of the DA. Because the large degrees of freedom in our For the remaining variables, 30 arcsec data were not available 306 281 test (N17,000) make this result likely even if the deviation from from SCAS, so we followed the approach of Hamann and Wang 307 282 normality was small, we examined the distribution of our data (2005) to develop adjusted high-resolution spatial estimates. For 308 283 further. A preponderance of the data closely fit the normal this, weED used 30 m digital elevation model (DEM, from Davis 309 t1:1 Table 1 t1:2 Summary statistics of deadwood tree stems on Whitewing Mountain and San Joaquin Ridge t1:3 Aspect N Mean Basea SD Basea Mean Length SD Length Mean Dia SD Dia Stem Orientationb (m) (m) (cm) (cm) t1:4 Whitewing Mountain t1:5 SW ridgetop 69 1.68 0.47 4.5 2.1 23.4 12.7 N, NW t1:6 SW summit 23 1.57 0.5 3.1 2.2 30.2 12.2 N, NW t1:7 NW slope 28 1.82 0.39 3.3 1.7 23.9 10.4 NW, E t1:8 Summit plateau 188 1.97 0.16 3.2 1.5 22.1 9.9 E, NE t1:9 NW slope 263 1.93 0.26RRECT 5.0 2.4 28.7 15.5 SE, N t1:10 NW summit 129 1.93 0.26 3.7 1.9 23.6 10.7 N, SE t1:11 NW slope, low 64 1.98 0.13 5.4 3.2 31.0 18.0 N, S t1:12 NW slope, mid 226 1.99 0.09 4.0 2.3 23.1 10.9 N, E t1:13 NW slope, high 78 1.99 0.11 4.0 2.3 26.9 11.7 S, SE t1:14 SE slope, high 13 2.00 0.00 3.2 1.6 24.1 13.7 E, SE t1:15 SE slope, mid 15 2.00 0.00 4.2 1.8 25.9 6.4 E, NE t1:16 E slope, high 166 1.99 0.07 3.7 1.7 22.6 11.4 E, NE t1:17 E slope, high 6 2.00 0.00 7.4 2.9 51.3 25.4 E t1:18 E slope, high 80 2.00 0.00 3.4 1.6 23.1 10.9 NE, E t1:19 E slope, mid 120 1.99 0.09 4.1 2.1 26.7 14.7 E, NE t1:20 NE summit 55UNCO 1.93 0.20 4.4 2.5 34.0 13.7 NW, NE t1:21 N slope 152 1.55 0.50 4.4 2.7 26.7 22.9 S, SE t1:22 TOTAL 1675 1.91 0.28 4.1 2.3 26.9 15.0 t1:23 t1:24 San Joaquin Ridge t1:25 S ridgetop 22 1.27 0.46 4.1 1.6 23.1 12.2 SW, S t1:26 Central ridgetop 18 1.33 0.49 3.5 1.5 22.4 10.7 SW, W t1:27 N ridgetop 20 1.30 0.47 3.7 1.8 23.6 12.7 SW, W t1:28 TOTAL 60 1.31 0.46 3.7 1.6 22.9 11.2 Aspect, number of stems (N), condition of stem base (with or without stump attached), mean and standard deviation (SD) stem length and stem diameter (Dia), and primary and secondary orientations (from windrose analysis) are given for deadwood grouped by location on the mountain. The Glass Cr vent is NE-E of Whitewing t1:29 Mtn and NE of San Joaquin Ridge. t1:30 a Stem base: 1 = stump attached, 2 = stump absent. t1:31 b Measured as the direction in which the tree lies from base toward tip. ARTICLE IN PRESS

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310 et al., 1998) tiles for the eastern Sierra Nevada ecoregion, and elevation in each equation to estimate lapse rates for climatic 324 311 intersected these with climate data from the PRISM 4 km2 model data by elevation to adjust temperature and precipitation 325 312 (Daly et al., 1994), extracting the PRISM climate data with between the mean elevation of the 4 km2 PRISM tile for that 326 313 latitude, longitude, and elevation. We then regressed response- including Whitewing and the actual elevation for Whitewing. 327 314 surface equations of latitude, longitude, and elevation of the DEM Surface analysis regressions were done in SAS PROC GLM 328 315 tiles against the PRISM tiles. Rather than using regression (SAS, 2004) and first derivatives were computed in Mathema- 329 316 equations of Hamann and Wang (2005), which were based on tica (Wolfram Research, 2004). In nearly all cases, the adjusted 330 317 Canadian locations, we used modified multi-order surface data improved fit to the station data relative to the 4 km2 model. 331 318 equations of the form: (latitude + longitude)n + elevation + Similar adjustments to PRISM were made to estimate high- 332 319 elevation × (latitude + longitude)n − 1,whereN90% fit was ob- resolution current climate for San Joaquin Ridge. 333 320 tained when n equaled 5 for the temperature data and 9 for the To compare inferred paleoclimate at WhitewingF Mtn and San 334 321 precipitation data. While this is an overfit as our data are spatially Joaquin Ridge with other locations where the species grow at 335 322 correlated, the high degrees of freedom ensure high fit. As in present we modeled climate at two additional sites: Carson 336 323 Hamann and Wang (2005), we took the first derivative for Valley, NV (elev 1701 m), one of the few occurrences of sugar 337 PROO ED

RRECT

UNCO

Figure 3. Dated tree-ring series for 45 deadwood samples from Whitewing Mtn, 11 deadwood samples from San Joaquin Ridge, and 27 live stunted trees on Whitewing Mtn. Sample numbers listed next to each series correspond to Appendix 1. For Whitewing, these are WW samples, for San Joaquin Ridge, they are SJR samples in Appendix 1. Species identifications from wood anatomy are given after the sample number for the Whitewing series, where Pial is Pinus albicaulis, Pimo is P. monticola, Pila is P. lambertiana, Pico is P. contorta, Pije is P. jeffreyi, and Tsme is Tsuga mertensiana, wpg is white pine group and ypg is yellow pine group. A question mark indicates a wood sample whose taxonomic identity could not be determined. All live samples and San Joaquin deadwood samples were P. albicaulis. ARTICLE IN PRESS

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338 pine east of the Sierran crest, and Grizzly Peak, Klamath Mtns, 2 P. jeffreyi,and6Tsuga mertensiana samples. Seven additional 372 339 northwest California (2059 m), one of the few locations where samples were identified to a yellow-pine group, which includes 373 340 the six Whitewing deadwood species occur in relatively close P.jeffreyi, P.contorta,andP.ponderosa,and2additionalsamples 374 341 association. We estimated the current climate at these locations to a white pine group, which includes P.monticola, P.flexilis,and 375 342 with the unadjusted 4 km2 PRISM dataset. P. lambertiana. Twenty-nine samples were rooted buried stumps 376 343 To evaluate the possibility of climatic rather than volcanic and represented the taxonomic diversity of the total collection. All 377 344 cause for forest death on Whitewing Mtn, we extracted from the samples from San Joaquin Ridge were P. albicaulis. 378 345 ITRDB ten high-elevation regional tree rings chronologies 346 growing outside the volcanic influence zone (ITRDB, 2005d), Deadwood stem ages and dates 379 347 and conducted MANOVA (SAS, 2004) of ring-width between 348 the MCA, LIA, and modern time periods for 25-yr windows We processed 85 deadwood samples fromF Whitewing Mtn 380 349 throughout the last 1000 yr, and ring-width in the year AD1350 and 25 from San Joaquin Ridge for cross-dating. Of these we 381 350 compared to the prior 24 yr. We also computed mean determined explicit calendar dates for 45 samples from 382 351 sensitivities of these chronologies to compare against the Whitewing Mtn and 11 from San Joaquin Ridge (Fig. 3). 383 352 Whitewing deadwood value. Whitewing Mtn samples had an average series length of 165 yr, 384 mean sensitivity of 0.171, and average ring width of 0.85 mm. 385 353 Results Dates for the oldest (innermost) rings ranged AD 815–1211, and 386 youngest (outermost) rings ranged 1063–AD 1350. Samples of 387 354 Deadwood characteristics, stem orientation, and species all species were well represented throughout the period with no 388 355 identification temporal gaps in thePROO record. The San Joaquin Ridge samples had 389 an average series length of 121 yr and spanned the period AD 390 356 We mapped and measured 1675 deadwood stems from 17 925–1298, with a 31 yr gap, AD 989–1019. 391 357 locations on Whitewing Mtn and 60 deadwood stems from 3 Live krummholz whitebark pines sampled in rock outcrops 392 358 locations on San Joaquin Ridge (Table 1). Most stems on below the summit of Whitewing Mtn had an average series 393 359 Whitewing Mtn were unrooted and downed, with their basal length of 86 yr. The oldest sample dated to AD 1723. Three 394 360 stumps broken off, while more stems on San Joaquin Ridge trees wereED over 200 yr old; the remaining 24 samples were less 395 361 retained their stumps. Mean deadwood stem lengths and than 120 yr old (Fig. 3). 396 362 diameters respectively were 4.1 m and 26.9 cm on Whitewing 363 Mtn, and 3.7 m and 22.9 cm on San Joaquin Ridge. Based on Dating the glass creek vent eruption 397 364 windrose summaries, the predominant orientation of downed 365 stems was north to east on Whitewing Mtn, and southwest to We were successful in applying three independent methods 398 366 west on San Joaquin Ridge (Table 1). to corroborate a date for the Glass Creek Vent eruption. Al- 399 367 Taxonomic identifications from deadwood anatomy were though wind erosion removed rings from the outer circumfer- 400 368 made on 78 samples from Whitewing Mtn and 17 from San ences of most deadwood samples on Whitewing Mtn and San 401 369 Joaquin Ridge (Appendix 1). Diagnostic traits allowed explicit Joaquin Ridge, we found one sound stem that retained its outer 402 370 identification of six species on Whitewing, including 42 Pinus bark edge and had the youngest date of all samples. Sample 403 371 albicaulis,5P. lambertiana,11P. monticolaRRECT,3P. contorta, WW11, a rooted P. alb ic au li s stem, had a branch knot 404

UNCO

Figure 4. Cross-sections of Whitewing sample WW11, Pinus albicaulis, whose outer growth ring was protected from erosion by a dead knot. The outermost ring dates to AD 1350 and lacks the final cells of the growing season, suggesting that the tree died near the end of the growing season (late summer) AD 1350 in the Glass Creek eruption. (A) Stem cross-section showing the protected outer rings growing in the dead knot cavity and the outer stem (waney) edge. (B) Magnification of the outermost growth rings showing the incomplete final ring lacking the typical terminal small cells. ARTICLE IN PRESS

8 C.I. Millar et al. / Quaternary Research xx (2006) xxx–xxx t2:1 Table 2A t2:2 Sapwood surveys in live trees and sapwood dating in deadwood samples t2:3 Survey of Sapwood Rings in Live Trees t2:4 Species N Mean number Standard Sapwood Rings deviation t2:5 Pinus albicaulis (YNP) 181 63.5 15.7 t2:6 Pinus albicaulis (GC) 42 61.2 18.0 t2:7 Pinus albicaulis (alla) 223 63.0 16.2 t2:8 Pinus flexilis 96 70.2 17.5 t2:9 Pinus monticola 24 45.3 15.9 t2:10 Pinus contorta 30 88.2 22.5 t2:11 white pine groupb 120 65.2 19.8 F Results from a survey of number of sapwood rings in live trees from Yosemite National Park (YNP) for Pinus albicaulis) and the Glass Creek Watershed (GC) t2:12 for all species. Figure 5. Ring-width trace from deadwood stump sample GC 7/13/98-1, t2:13 a Combined dataset from YNP and GC samples. putatively identified as Pinus contorta, growing at 2081 m elevation in Glass t2:14 b Dataset derived by merging values from P. flexilis and P. monticola samples. Creek watershed. This tree survived the AD 1350 eruption, presumably due to its protected location, but shows severely depressed growth during the following 405 embedded in the main stem. The branch died before the main growing season and in the subsequent year (AD 1351 and 1352 , respectively), 406 stem, creating a knot cavity that protected the bark and outer corroborating the estimated date for the eruption. 407 rings of the main stem (Fig. 4A). The ring series of the lower PROO 408 main stem dated AD 1052–1187; the protected stem series in tephra. The sample was located at 2801 m in a narrow col 426 409 the knot cavity overlapped this by 10 rings and had an inner date 1.5 km west of the Whitewing summit; wood anatomy indicates 427 410 of AD 1177. The terminal (outer) ring dated to AD 1350 and it is lodgepole pine. The stem date range was AD 1201–1467. 428 411 appeared incomplete (Fig. 4B). This ring appeared to lack the The AD1350 growth ring (1.068 mm) is near-average width 429 412 narrow latewood cells that typically signify the end of the (1.310 mm), but ring AD1351 is highly suppressed (0.030 mm) 430 413 growing year. We estimated the death date of this sample as late and comprisesED only 1–2 cells (Fig. 5). Ring AD1352 is also 431 414 summer AD 1350, and propose this as the eruption date. very narrow (0.162 mm). 432 415 Thirteen deadwood samples from Whitewing Mtn had dateable 416 heartwood/sapwood boundaries, including six whose boundaries Current and paleo-climate at Whitewing Mtn and San Joaquin 433 417 dated to the late 13th century. Using species-specific values from Ridge 434 418 our survey of 343 live local trees (Table 2A), we estimated death 419 dates for the six deadwood series. The range of mean dates using The first two canonical vectors of the discriminant analysis 435 420 this method was AD 1322–1370 with 95% confidence intervals accounted for 97% of the differences in current climate space of 436 421 extending the range to AD 1290–1414 (Table 2B). the five deadwood species on Whitewing Mtn as estimated from 437 422 During an extensive study of forest dynamics in Glass Creek 423 watershed, we found only one deadwood sample whose ring Table 3 t4:1 424 series extended through AD 1350. Sample GC 7/13/98-1RRECT was an Canonical discriminant analysis of the differences in contemporary climate 425 upright, rooted stump, 107 cm in diameter, buried in coarse space for distributions of P. albicaulis, P. monticola, P. lambertiana, P. jeffreyi, and P. contorta in the Sierra Nevada and western Great Basin t4:2 t3:1 Table 2B (A) Summary t4:3 t3:2 Sapwood surveys in live trees and sapwood dating in deadwood samples Canonical vector 1 Canonical vector 2 t4:4 t3:3 Estimates of death dates in Whitewing Mtn deadwood samples Correlation 0.76 0.45 t4:5 t3:4 Whitewing Species Pith yr Outer Sapwood Estimated Death a Percent 81 16 t4:6 Sample ID ID AD Ring Boundary Mean and CI, t4:7 yr AD yr AD yr AD (B) Individual correlations t4:8 t3:5 WW505 Pial 1067 1308 1259 1322 (1290–1354) UNCO Correlations t4:9 t3:6 WW17 wpg 1178 1332 1282 1347 (1308–1386) t3:7 WW105 wpg 1211 1328 1283 1348 (1309–1387) Annual max temp 0.95 −0.17 t4:10 t3:8 WW113 wpg 1190 1324 1289 1354 (1315–1393) Annual min temp 0.95 −0.05 t4:11 t3:9 WW 109 wpg 1187 1334 1292 1357 (1318–1396) Annual precipitation 0.18 0.92 t4:12 t3:10 WW2 Pico 1157 1326 1282 1370 (1326–1414) January max temp 0.92 −0.29 t4:13 July max temp 0.89 0.13 t4:14 Sapwood boundary dates and estimates of death dates for six deadwood Jan min temp 0.90 0.24 t4:15 Whitewing Mtn samples. Death dates are calculated by adding the species or July min temp 0.80 0.06 t4:16 group mean number of sapwood years from the surveys of local live trees to the Jan precipitation 0.22 0.92 t4:17 date of deadwood sapwood–heartwood boundaries. Pith dates are dates of tree July precipitation −0.58 0.07 t4:18 birth; death dates are given by mean year with 95% confidence-interval ranges. The resulting range of death dates corroborates the eruption date inferred from (A) Overall correlation of climate variables to first two canonical vectors and t3:11 other methods (AD 1350). percent of variation explained by first two canonical vectors. (B) Correlations of t3:12 a Pial is Pinus albicaulis; Pico is Pinus contorta; wpg is white pine group. individual climate variables to first two canonical vectors. t4:19 ARTICLE IN PRESS

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438 their current Sierra Nevada distribution and PRISM climate The paleoclimate modeled for Whitewing during the Medieval 456 439 model (Table 3). The first vector showed the greatest difference period was significantly warmer and slightly drier than present 457 440 among species, accounting for 81% of the differences. (Table 4). Medieval mean annual minimum temperature was 458 441 Temperature variables were strongly correlated with scores on warmer than current by 3.2°C, with large differences in winter 459 442 this vector, and precipitation, excepting July precipitation, was (+3.5°C, January) and summer (+4.0°C, July). Mean annual 460 443 strongly correlated with the second vector. July precipitation maximum temperature was also greater in the Medieval period 461 444 was negatively correlated with the first vector. Scatter diagrams (+2.3°C), with greater differences in winter (+3.2°C, January) 462 445 from discriminant analysis for the individual species indicate than summer (+2.6°C, July). Annual precipitation was less by 463 446 differences in climate space among the species (Figs. 6A–E); 24 mm. The modeled Medieval climate for Whitewing Mtn 464 447 the greatest difference was between whitebark pine and sugar compared closely with current conditions estimated from PRISM 465 448 pine. From the values for the mean overlap among the five for the Carson Range extant sugar pine location,F 200 km distant 466 449 species (Fig. 6F), we estimated mean values for six temperature from Whitewing Mtn and 1350 m lower, and for the Grizzly Peak 467 450 and three precipitation variables (Table 4), which we propose mixed conifer stand, 580 km distant and 992 m lower. 468 451 reflect a potential paleoclimate on Whitewing Mtn during the Our analyses of mean ring-widths and mean sensitivities 469 452 time the species co-occurred. With the exception of minimum from the Whitewing Mtn series relative to other regional 470 453 temperatures, RMSDs were less than 15% of the station means, chronologies indicated little evidence for climatic rather than 471 454 and all RMSDs were equal to or less than those reported in volcanic cause of death. Compared to 40 long regional tree-ring 472 455 Hamann and Wang (2005). chronologies, meanPROO sensitivity of the Whitewing set ranked 473 ED

RRECT

UNCO

Figure 6. Scatter diagrams of discriminant analysis scores for Sierra Nevada/western Great Basin species distribution ranges. Each point is an individual polygon from the Sierra Nevada GAP range dataset. (A) Pinus albicaulis (Pial), (B) P. lambertiana (Pila), (C) P. monticola (Pimo), (D) P. jeffreyi (Pije) and (E) Tsuga mertensiana (Tsme). (F) All species. Circles representing 90% of the discriminant values for each species show overlap among species (shaded), the mean of which was modeled to estimate climate at time of species sympatry (paleoclimate of Whitewing, PW); centroids for each species are indicated. Current climate points for Whitewing Mtn (WW) and San Joaquin Ridge (SJR) are indicated. ARTICLE IN PRESS

10 C.I. Millar et al. / Quaternary Research xx (2006) xxx–xxx t5:1 Table 4 Current and paleohistoric climate estimates for Eastern Sierra Nevada as modeled and adjusted from PRISM climate model (Daly et al., 1994) and discriminant t5:2 analysis t5:3 Location Ann ppt July ppt Jan ppt Ann min Jan min July min Ann max Jan max July max (mm) (mm) (mm) temp (°C) temp (°C) temp (°C) temp (°C) temp (°C) temp (°C) t5:4 (A) Current climate: 1971–20AD 00 t5:5 Carson Range, NV (e Sierra sugar 972 16 153 −0.5 −7.2 8.0 13.1 4.0 24.3 pine stand) t5:6 Grizzly Peak, NW CA (6 species 959 15 178 0.4 −5.1 7.5 15.6 4.4 27.9 growing in near-sympatry) t5:7 San Joaquin Ridge 945a 5a 195a −4.5a −9.8b 3.4b 10.9a 0.7b 21.2b t5:8 Whitewing Mtn 1064a 14a 184a −3.7a −10.0b 3.6b 11.0a 1.4Fb 21.5b t5:9 t5:10 (B) Paleoclimate: AD 800–1350 t5:11 Whitewing Mtn 1040 13 186 −0.5 −6.5 7.6 13.3 4.6 24.1 t5:12 t5:13 (C) Difference in Whitewing Mtn Climate Values t5:14 Paleo-Current −24 −1 +2 +3.2 +3.5 +4.0 +2.3 +3.2 +2.6 t5:15 t5:16 (D) Deviations of PRISM estimates from instrumental station records t5:17 RMSD/Mean 0.04a 0.13a 0.05a 0.44a 0.52b 0.56b b0.01a 0.03b 0.01b (A) Current climate estimates for four locations: Carson Range, NV location of extant eastern Sierra sugar pine (1350 m below Whitewing Mtn summit); Grizzly Peak, northwest CA location of near-sympatric extant occurrence of six Whitewing deadwood species (992 m below WhitewingPROO Mtn summit); Whitewing Mtn,; and San Joaquin Ridge. Estimates based on period-of-record 1971–2000 and 4 km2 PRISM model except January and July minimum and maximum temperatures, respectively, which are based on 30 arcsec PRISM model; for Whitewing and San Joaquin Ridge, PRISM estimates of precipitation, annual minimum and annual maximum temperatures are adjusted for elevation at 30 m intervals. (B) Paleoclimate values estimated from 4 km2 PRISM model based on the mean jointly classified observations derived from discriminant analysis of multi-species climate space using five deadwood species present on Whitewing Mtn and dating to AD 800–1350. (C) Differences in climate values for Whitewing Mtn between time periods (Paleoclimate-Current Climate). (D) Root mean squared deviations (RMSD)of adjusted PRISM estimates from the instrumental records for four weather stations (Bishop, Lee Vining, Bridgeport, and Bodie CA, WRCC, 2005), based on equivalent periods- t5:18 of-record (1971–2000). ED t5:19 a Estimates adjusted from the 4 km2 PRISM model for elevation at 30 m intervals. t5:20 b Estimates based on unadjusted 30 arcsec PRISM estimates.

474 fourth from the lowest, similar to values from mid-elevation assume the yellow pine group to be represented by Jeffrey pine 499 475 (1800–2200 m) mesic, westslope chronologies, and signifi- and not Ponderosa pine (Pinus ponderosa) because the latter 500 476 cantly lower than means from subalpine forests growing at grows at distant, low, westslope, elevations in the Sierra. It 501 477 elevations comparable to Whitewing Mtn. Relative to ten high- remains, however, a candidate. Within subgenus Haploxylon, 502 478 elevation regional chronologies, mean sensitivities of the species-specific diagnostics distinguished whitebark pine and 503 479 Whitewing set were not significantly greater during the mid- sugar pine, while western white pine and limber pine were 504 480 1300s relative to a reference of AD 1300–1500 (P b 0.001). difficult to separate and identification depended on sample quality. 505 481 Similarly, although mean ring-width for the periodRRECT AD1325– The identification of six conifer species growing together in 506 482 1350 was less than during AD 1300–1325, it was significantly forest stand conditions at elevations above 3000 m on Whitewing 507 483 greater than means for all 25-yr periods during four centuries of Mtn was an unexpected finding from our study. The possibility 508 484 AD1450–1850 (P b 0.001). Ring-width during the year that the stems did not originate from trees growing on the 509 485 AD1350 for the ten high-elevation chronologies (from outside summit, rather were transported upslope by a volcanic blast from 510 486 the volcanic influence zone) was greater, though not signifi- lower elevation forests, is counter-indicated by the presence of 511 487 cantly (P N 0.07) than the mean during the previous 24 yr. rooted stumps representing the range of species on the summit 512 plateau. Only whitebark pine currently occurs at similar 513 488 Discussion and conclusions elevations elsewhere in the Sierra Nevada, although usually in 514 UNCO krummholz form and a few clusters of krummholz whitebark 515 489 Deadwood forest composition and age pine currently occur in protected rock outcrops on the slopes of 516 Whitewing Mtn and San Joaquin Ridge. The deadwood stems, 517 490 The abundant deadwood on Whitewing Mtn and San Joaquin by comparison, are scattered widely on the summit plateau and 518 491 Ridge was extremely well preserved, enabling taxonomic slopes, have long, straight stems and relatively large diameters, 519 492 identification to species level with high confidence. Diagnostic indicating a tall forest structure. 520 493 traits readily distinguished the samples to two genera, Tsuga and Lodgepole pine and mountain hemlock are currently at the 521 494 Pinus. Only one hemlock species (Tsuga mertensiana) is currently elevation of Whitewing Mtn elsewhere in the Sierra where 522 495 native to the Sierra Nevada, and we assume this to be the conditions are protected. In windy, exposed locations mountain 523 496 Whitewing taxon. Diagnostics readily separate the subgenera hemlock rarely occurs at this elevation, and lodgepole pine is 524 497 within Pinus. Within subgenus Diploxylon, P. contorta is usually stunted. These species currently grow in straight-stem 525 498 distinguishable from taxa within subsection Ponderosae.We condition more than 200 m below the summit of Whitewing 526 ARTICLE IN PRESS

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527 Mtn. Western white pine is a common but sparsely distributed Whitewing samples over time nor evidence in other regional 582 528 species of the upper montane zone in the eastern Sierra. In the high-elevation forests for stress in this period. To the contrary, 583 529 region of Whitewing Mtn, it occurs mixed with other pines on evidence points to favorable growth conditions during the early– 584 530 the slopes of Whitewing Mtn and San Joaquin Ridge more than mid 1300s. Similarly, no evidence indicates that, prior to late 585 531 250 m below the summits. Jeffrey pine is locally abundant in summer, the year AD1350 was anomalously stressful. Only in 586 532 this region more than 400 m below the Whitewing summit. AD1351 at Whitewing Mtn was an unprecedented growth 587 533 An especially surprising identification from Whitewing Mtn depression obvious. Considered together, the evidence points to 588 534 was sugar pine. This species is typical of low- to mid-montane, volcanic eruption as the cause of forest death on Whitewing Mtn, 589 535 mesic habitats of southern Oregon to northern Baja California not other environmental or climatic stress. Based on stem 590 536 (Critchfield and Little, 1966). In the Sierra Nevada, sugar pine is orientations, it appears more likely that the eruption killed the 591 537 a component of the west-slope mixed-conifer forest, and trees, which later blew down in winds or fellF along slope gravity, 592 538 extends 610–2285 m (Kinloch and Scheuner, 1990). Occasional rather than were broken directly by the volcanic blast. 593 539 outliers occur higher, and the nearest native sugar pine to Our three independent methods corroborate an eruption date 594 540 Whitewing Mtn occurs west of the Sierra crest in the upper of Glass Creek Vent as late summer AD 1350. This estimate 595 541 watershed of the Middle Fork , 25 km distant falls in the range previously indicated by radiocarbon and 596 542 and ∼700 m below Whitewing Mtn (Griffin and Critchfield, minimum tree-ring methods (Miller, 1984, 1985; Sieh and 597 543 1976). The closest occurrence east of the Sierra crest is in Bursik, 1986; Sorey et al., 1998). A fourth line of evidence for 598 544 Alpine County, 100 km northwest and 1150 m lower than this date comes from tree-ring series dates of dead and live 599 545 Whitewing (Griffin and Critchfield, 1976). limber pine 0.5 km north of the Whitewing summit (Millar, C.I., 600 546 The identification of sugar pine in the Whitewing area is manuscript in preparation),PROO which we dated as continuous from 601 547 supported by independent evidence: (1) several wood samples from 1362 BC to AD 1339, a gap for 52 yr, then a continuous record 602 548 Whitewing Mtn, first discovered in the late 1970s, were sent to two from AD 1392 to the present. 603 549 wood identification laboratories, both of which reported the 550 samples as sugar pine (1980, letters on file from Forest Products Paleoclimate, current and future climates 604 551 Lab, Madison, WI and University of California Forest Products 552 Lab, Richmond CA); (2) wood from Inyo Craters tephra soil TheED range of dates for the deadwood samples, AD 815– 605 553 horizon, extracted from a roadcut near Deadman Creek, was noted 1350, coincides with the period identified from multiple proxies 606 554 without documentation as sugar pine (Stine et al., 1984); (3) in the Sierra Nevada and western Great Basin as the Medieval 607 555 anecdotal reports from a Bishop, CA woodsworker detail the “last Climate Anomaly. This period overlaps nearly exactly two 608 556 old-growth sugar pine” having been sawn from the upper Dry regional centennial-scale droughts, dated AD 900–1112 and 609 557 Creek watershed, adjacent to San Joaquin Ridge in the mid 1940s AD1200–1350, identified from lowered lake and river levels 610 558 (1995 unpublished oral history report on file, USFS, Bishop, CA). (Stine, 1990, 1994). Extensive drought during the Medieval 611 559 No live native sugar pine is known from this region at present, period has been further interpreted from lake sediments (Yuan 612 560 despite extensive field surveys. et al., 2004; Benson et al., 2002; Li et al., 2000; Kleepe, in 613 561 The species diversity, short ring-series length, and compla- press), tree-ring reconstructions (Meko et al., 2001), and glacial 614 562 cent nature of growth in the Whitewing Mtn samples initially records (Konrad and Clark, 1998). Tree-ring reconstructions 615 563 made cross-dating difficult. Our approach,RRECT using multiple indicate increased temperature relative to present (Graumlich, 616 564 methods and cross-checking each preliminary date, provided a 1993; Scuderi, 1993) and higher treelines (Graumlich and 617 565 final set of dates for Whitewing and San Joaquin samples whose Lloyd, 1996; Lloyd and Graumlich, 1997), and pollen 618 566 accuracy has high confidence. The diversity and number of reconstructions show greater abundance of fir in high-elevation 619 567 samples spanned the Medieval period and dated AD 815–1350 communities than at present (Anderson, 1990). 620 568 with no indication of older samples. This suggests the forest The ecologic patterns and climatic estimates at Whitewing 621 569 established rapidly, and possibly the earliest trees colonized the and San Joaquin Ridge corroborate studies showing significant 622 570 summit after a previous eruption of the Inyo Craters. Medieval warmth in the California region but provide evidence 623 for differences between high and low elevations in moisture 624 571 Age of the glass creekUNCO vent eruption availability. Whereas mid-low elevations in the Sierra Nevada 625 experienced extreme Medieval drought, precipitation at White- 626 572 The end of the Medieval forest on Whitewing Mtn appears to wing appears to have been adequate to support mesic-adapted 627 573 have resulted from a volcanic eruption at Glass Creek Vent, as species. Excessive temperatures at low-mid elevations would 628 574 indicated in several ways. First, the slope of the outer ring dates force montane conifers uphill where temperatures were 629 575 in the Whitewing series is steep (Fig. 3) and, allowing for moderate. In contrast to lower elevations, however, high plateaus 630 576 variable wood erosion, suggests that that the trees died and summits of the eastern Sierra appear to have retained rela- 631 577 synchronously. If the trees had been experiencing increased tively more precipitation due to mountain meteorological pro- 632 578 environmental (fire or insect) or climatic (drought) stress, the cesses that favor orographic precipitation in winter and summer 633 579 ring widths in the early–mid 1300s would be expected to convective moisture. Further, the locations of the study sites 634 580 decrease and mean sensitivities increase. We found, to the relative to the low Sierran divide along San Joaquin Ridge 635 581 contrary, no significant differences in mean sensitivities in the positioned them to capture more precipitation from Pacific storms 636 ARTICLE IN PRESS

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637 than other eastside locations. Thus, even while severe drought the manuscript; Chris Daly for offering new high-resolution 692 638 was experienced at lower elevations, the high elevation and PRISM data; Veronique Greenwood and Karolyn Wyneken for 693 639 position of Whitewing received adequate precipitation capable of field assistance; Jim Jensen, Tom Higley, and Wally Woolfen- 694 640 supporting mesic and warm adapted species. den for early reconnaissance work, and the NOAA World Data 695 641 That the Medieval forest on Whitewing was growing under Center for Paleoclimatology, International Tree-Ring Data 696 642 mild, favorable conditions (warm with adequate moisture) is Bank, for providing tree-ring chronologies. 697 643 further indicated by extremely low mean sensitivities and large 644 average ring widths. These variables reflect relative tree health Appendix A. Locations and descriptions of deadwood trees 698 645 and growth in that larger ring width and lower mean sensitivity stems sampled for species identification from wood 699 646 values occur when trees grow under less limiting environmen- anatomy on Whitewing Mountain and San Joaquin Ridge 700 647 tal conditions. As indicated by our comparison of the F 648 Whitewing dataset with 40 regional chronologies, mean Samples indicated as dated are graphed in Figure 3 701 649 sensitivities as low as the Whitewing deadwood set rarely 702704 b 650 occur in trees growing in subalpine conditions, where physical Sample Stem Length and Condition Stump Dated? Species ID 708710711712706 a 707709 651 stress dominates interannual ring variability, and mean ID Diameter 652 sensitivities typically range above 0.3. The similarity of Whitewing Mountain-North Slope: 714 653 WW1–97 9 m, 20 cm upright rooted yes Pinus 716718 climates at the extant eastside sugar pine stand in the Carson 717719 654 stem albicaulis Range, NV and the mixed conifer stand at Grizzly Peak, WW2–97 12 m, 91 cm downed absent no Tsuga 721723 655 northwest CA to the modeled paleoclimate for Whitewing Mtn log mertensiana 722724 656 is additional support for an interpretation that the conditions at WW3–97 1 m, 35 cm upright rooted no P. albicaulis 726728 PROO 727 657 Whitewing were warm but not excessively dry. stem 658 WW4–97 12 m, 81 cm downed absent yes yellow pine 730 A projection of warm Medieval temperatures with only small 731732 659 log grp decreases in precipitation at high elevations is not inconsistent WW158 5 m, 55 cm downed absent yes T. mertensiana 734736 660 with extreme drought at lower elevations indicated by other log 735 661 studies. Warm winter temperatures would result in significantly WW159 3 m, 20 cm downed absent yes T. mertensiana 738740 662 reduced winter snowpack, early run-off, lengthening of the ED log 739 663 WW160 7 m, 40 cm downed absent yes T. mertensiana 742744 Mediterranean summer drought, and reduced available mois- 743 664 – log ture. This situation resembles 20th 21st century trends in the WW161 8 m, 40 cm upright rooted no P. albicaulis 746748 665 Sierra Nevada, where increasing minimum temperatures, stem 747 666 especially in winter, are reducing snowpack accumulation, WW510–98 3 m, 23 cm upright rooted no P. albicaulis 750752 667 accelerating early run-off, and leading to effective drought stem 751 668 WW511–98 1 m, 20 cm upright rooted yes P. albicaulis 754756 during the spring-fall growing season despite lack of annual 755 669 stem average decrease in precipitation (Dettinger et al., 2004). The WW512–98 2 m, 25 cm downed absent yes P. albicaulis 758760 670 modeled Whitewing Medieval climate closely compares to log 759 671 climate projections for California in AD 2070–2099 (Hayhoe WW513–98 4 m, 31 cm upright rooted yes P. albicaulis 762764 672 et al., 2004). In that study, average temperature increases of stem 763 – 766768 673 2.3–5.8°C were projected and slight increases orRRECT decreases in WW514 98 3 m, 40 cm upright rooted yes P. albicaulis 767 674 − – stem precipitation (+38 mm to 157 mm). Coupled vegetation WW515–98 3 m, 35 cm downed absent no P. albicaulis 770772 675 climate projections for 2070–2099 inferred significantly log 771 676 reduced spring snowpacks and earlier runoff. Based on those WW516–98 1 m, 33 cm upright rooted yes P. albicaulis 774776 677 conditions, Hayhoe et al. (2004) estimate 75–90% reduction in stem 775 678 – WW517–98 3 m, 40 cm upright rooted yes P. albicaulis 778780 California subalpine forest by AD 2070 2099. Recognizing 779 679 stem significant CO2 differences between future projected and 782 680 Medieval climates, our empirical findings of significant Whitewing Mountain–Northwest Slopes and NW Summit: 784 681 increase in subalpine forest extent and diversity during similar WW 200 1 m, 28 cm rooted present no P. albicaulis 786788 682 climate conditions nonethelessUNCO raise questions about modeled stump 787 683 WW201 0.5 m, 28 cm rooted present no P. monticola 790792 results of future forest reductions in the subalpine zone. As we 791 684 stump have observed for the 20th century, subalpine forests in the WW202 0.3 m, 27 cm rooted present no yellow pine 794 685 Sierra Nevada often respond non-linearly with increasing stump grp 795796 686 temperature, showing abrupt changes and reversals (Millar WW203 0.6 m, 20 cm rooted present no P. albicaulis 798800 687 et al., 2004). Such trends may well ensue under future warming. stump 799 WW204 0.6 m, 15 cm rooted present no P. albicaulis 802804 803 688 stump Acknowledgments WW206 0.7 m, 28 cm rooted present no P. monticola 806808 stump 807 689 We thank Chris Daly, William Evans, Andreas Hamann, WW207 0.1 m, 22 cm rooted present no P. lambertiana 810812 690 Dave Hill, Stephen Gray, Robin Tausch, Alex Wiedenhoft, and stump 811 691 an anonymous reviewer for critical discussion and reviews of (continued on next page) ARTICLE IN PRESS

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Appendix A (continued ) Appendix A (continued ) 814816818819820 Sample Stem Length and Condition Stump Dated? Species ID b ID Diameter a 949951 815817 ID Diameter a Whitewing Mountain–Central Summit Plateau: 956 822 Whitewing Mountain–Northwest Slopes and NW Summit: WW19–95 5 m, 48 cm downed absent yes P. albicaulis 958960 824826 WW208 0.2 m, 31 cm rooted present no P. monticola log 959 825 stump WW20–95 6 m, 35 cm downed absent yes yellow pine 962 828830 WW209 0.2 m, 31 cm rooted present no P. albicaulis log grp 963964 829 stump WW21–95 3 m, 22 cm downed absent yes P. albicaulis 966968 832834 WW210 0.2 m, 31 cm rooted present no P. albicaulis log 967 833 stump WW106–95 4 m, 35 cm downed absent no P. monticola 970972 836838 WW211 0.4 m, 21 cm rooted present no P. albicaulis log 971 837 stump WW107–95 5 m, 42 cm downed absentF no P. albicaulis 974976 840842 WW212 0.1 m, 27 cm rooted present no P. albicaulis log 975 841 stump WW108–95 2 m, 24 cm downed absent no P. albicaulis 978980 844846 WW213 1.2 m, 30 cm rooted present no P. albicaulis log 979 845 stump WW109–95 3 m, 35 cm downed absent yes P. albicaulis 982984 848850 WW214 0.4 m, 25 cm rooted present no P. albicaulis log 983 849 stump WW110–95 7 m, 80 cm downed absent no P. monticola 986988 852854 WW215 1.3 m, 27 cm downed present no P. lambertiana log 987 853 log WW111–95 6 m, 65 cm downed absent yes P. albicaulis 990992 856858 WW216 0.2 m, 31 cm downed absent no T. mertensiana log 991 857 log WW112–95 4 m, 45 cm downed absent no white pine 994 860862 WW217 7.2 m, 100 cm downed present no T. mertensiana log grp 995996 861 log WW113–95 7 m, 75 cmPROO downed absent no P. albicaulis 9981000 864 WW218 8.2 m, 121 cm downed present no yellow pine log 999 865866 log grp WW114–95 4 m, 45 cm downed absent yes P. albicaulis 10021004 868870 WW219 1.3 m, 37 cm rooted present no P. lambertiana log 1003 869 stump WW115–95 7 m, 75 cm downed absent yes P. albicaulis 10061008 872874 WW220 0.2 m, 31 cm rooted present no P. monticola log 1007 873 stump WW116ED–95 6 m, 72 cm downed absent no yellow pine 1010 876 log group 10111012 878 Whitewing Mountain–North Summit Plateau: WW509–98 1 m, 40 cm upright rooted no P. albicaulis 10141016 880882 WW1–94 6 m, 43 cm downed absent yes P. contorta stem 1015 881 log 1018 884886 WW2–94 9 m, 41 cm downed absent yes P. contorta Whitewing Mountain–South Summit Plateau: 1020 885 log WW6–94 5 m, 25 cm downed absent yes P. lambertiana 10221024 888890 WW13–94 8 m, 41 cm downed absent yes P. contorta log 1023 889 log WW7–94 1 m, 38 cm upright rooted no P. albicaulis 10261028 892 WW14–95 7 m, 39 cm downed absent yes yellow pine stem 1027 893894 log grp WW9–94 9 m, 43 cm downed absent yes P. monticola 10301032 896898 WW15–95 5 m, 32 cm downed absent yes P. lambertiana log 1031 897 log WW10–94 4 m, 28 cm downed absent yes P. albicaulis 10341036 900 WW16–95 9 m, 78 cm downed absent yesRRECT yellow pine log 1035 901902 log grp WW501–98 2 m, 35 cm upright rooted yes P. albicaulis 10381040 904906 WW17–95 8 m, 55 cm downed absent yes P. albicaulis stem 1039 905 log WW508–98 1 m, 37 cm upright rooted no P. albicaulis 10421044 908910 WW101–95 7 m, 58 cm downed absent yes P. monticola stem 1043 909 log 1046 912 WW103–95 4 m, 45 cm downed absent yes white pine Whitewing Mountain–West Summit Ridge: 1048 913914 log grp WW8–94 5 m, 32 cm downed present no P. albicaulis 10501052 916918 WW105–95 6 m, 45 cm downed absent yes P. monticola log 1051 917 log WW502–98 1 m, 36 cm wood absent no P. albicaulis 10541056 920 segment 1055 922 Whitewing Mountain–Central Summit Plateau: WW503–98 2 m, 27 cm upright rooted yes P. albicaulis 10581060 924926 – UNCO 1059 WW3 94 9 m, 43 cm downed absent yes P. jeffreyi stem 925 log WW504–98 3 m, 36 cm upright rooted yes P. albicaulis 10621064 928930 WW4–94 6 m, 20 cm downed absent yes P. monticola stem 1063 929 log WW505–98 8 m, 42 cm downed absent yes P. albicaulis 10661068 932934 WW5–94 3 m, 45 cm downed absent yes P. monticola stem 1067 933 log 1070 936938 WW11–94 0.3 m, 30 cm upright rooted yes P. albicaulis San Joaquin Ridge: 1072 937 stem SJ1–98 9 m, 45 cm downed present no P. albicaulis 10741076 940942 WW12–94 7 m, 78 cm downed absent no P. jeffreyi log 1075 941 log SJ2–98 8 m, 43 cm downed present yes P. albicaulis 10781080 944946 WW18–95 8 m, 65 cm downed absent no P. albicaulis log 1079 945 log (continued on next page) 948950952953954 Sample Stem Length and Condition Stump Dated? Species ID b ARTICLE IN PRESS

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Appendix A (continued ) Davis, F.W., Stoms, D.M., Hollander, A.D., Thomas, K.A., Stine, P.A.,Odion, D., 1182 Borchert, M.I., Thorne, J.H., Gray, M.V., Walker, R.E., Warner, K., 1183 10821084108610871088 b Sample Stem Length and Condition Stump Dated? Species ID Graae, J., 1998. The California Gap Analysis Project-Final Report. 1184 10831085 ID Diameter a University of California, Santa Barbara, CA. http://www.biogeog.ucsb. 1185 1090 San Joaquin Ridge: edu/projects/gap/gap_rep.html. 1186 10921094 SJ3–98 7 m, 30 cm downed present yes P. albicaulis Dettinger, M.D., Cayan, D.R., Meyer, M.K., Jeton, A.E., 2004. Simulated 1187 1093 log hydrologic responses to climate variation and change in the Merced, Carson, 1188 10961098 SJ4–98 9 m, 38 cm downed present yes P. albicaulis and American River basins, Sierra Nevada, California, 1900–2099. Climatic 1189 1097 log Change 62, 283–317. 1190 11001102 SJ5–98 8 m, 40 cm downed present yes P. albicaulis Esper, J., Cook, E.R., Schweingruber, F.H., 2002. Low-frequency signals in 1191 1101 log long tree-ring chronologies for reconstructing past temperature variability. 1192 11041106 SJ6–98 6 m, 35 cm downed present yes P. albicaulis Science 295, 2250–2253. 1193 1105 log ESRI (Environmental Systems Research Institute), 2002. ArcINFO:F Release 8.3. 1194 11081110 SJ7–98 3 m, 22 cm downed present yes P. albicaulis Environmental Systems Research Institute, Redlands, California. 1195 1109 log Fritts, H.C., 1976. Tree Rings and Climate. Academic Press, New York. 1196 11121114 SJ2–1–99 6 m, 50 cm downed present no P. albicaulis Graumlich, L.G., 1993. A 1000-yr record of temperature and precipitation in the 1197 1113 log Sierra Nevada. Quaternary Research 39, 249–255. 1198 11161118 SJ2–2–99 1 m, 25 cm downed present no P. albicaulis Graumlich, L.J., Lloyd, A.H., 1996. Dendroclimatic, ecological, and geo- 1199 1117 log morphological evidence for long-term climatic change in the Sierra Nevada, 1200 11201122 SJ2–3–99 4 m, 30 cm downed present no P. albicaulis USA. Radiocarbon 51–59. 1201 1121 log Griffin, J.R., Critchfield, W.B., 1976. The distribution of forest trees in 1202 11241126 SJ2–4–99 2 m, 32 cm downed present yes P. albicaulis California. USDA Forest Service. Pacific Southwest Research Station 1203 1125 log Research Paper, vol. PSW-82. 114 pp. 1204 11281130 SJ2–5–99 3 m, 35 cm downed present no P. albicaulis Hamann, A., Wang, T.L., 2005. Models of climatic normals for genecology and 1205 PROO 1206 1129 log climate change studies in British Columbia. Agricultural & Forest 11321134 SJ2–6–99 7 m, 45 cm downed present yes P. albicaulis Meteorology 128, 211–221. 1207 1133 log Hayhoe, K., Cayan, D., Field, C.B., 2004. Emissions pathways, climate change, 1208 11361138 SJ2–7–99 6 m, 38 cm downed present yes P. albicaulis and impacts on California. Proceedings of the National Academy of Science 1209 1137 log 101, 12422–12427. 1210 11401142 SJ2–8–99 9 m, 43 cm downed present yes P. albicaulis Holmes, R.L., Adams, R.K., Fritts, H.C., 1986. Tree-ring chronologies of western 1211 1141 log NorthED America: California, Eastern Oregon, and Northern Great Basin with 1212 11441146 SJ2–9–99 5 m, 39 cm downed present no P. albicaulis procedures used in the chronology development work including user's manuals 1213 1145 log for computer programs COFECHA and ARSTAN. Laboratory of Tree-Ring 1214 11481150 SJ2–10–99 8 m, 41 cm downed present yes P. albicaulis Research, University of Arizona, Chronology Series VI. 1215 1149 log IAWA, 2004. List of microscopic features for softwood identification. 1216 1151 a International Association of Wood Anatomists Journal 25, 1–70. 1217 Diameters of basal-most part of stem. 1218 1153 b White pine group includes Pinus lambertiana, P. monticola and P. flexilis, ITRDB (International Tree-Ring Data Bank), 2005a. IGBP PAGES/World Data 1154 Center for Paleoclimatology, NOAA/NCDC Paleoclimatology Program, 1219 yellow pine group includes P. jeffreyi, P. contorta, and P. ponderosa. 1220 1156 Boulder, Colorado, USA. Chronology numbers Ca505 (C.W. Ferguson and M.C. Parker); Ca 567, Ca579, Ca 580, Ca606, Ca633, (J.C. King). 1221 ITRDB (International Tree-Ring Data Bank), 2005b. IGBP PAGES/World Data 1222 1157 References Center for Paleoclimatology, NOAA/NCDC Paleoclimatology Program, 1223 Boulder, Colorado, USA. Chronology numbers Ca533 (D.A. Graybill and 1224 1225 1158 Anderson, R.S., 1990. Holocene forest development and paleoclimatesRRECT within V.C. LaMarche); NV519, Ca605, Ca606, Ca633 (J.C. King). 1226 1159 the central Sierra Nevada, California. Journal of Ecology 78, 470–489. ITRDB (International Tree-Ring Data Bank), 2005c. IGBP PAGES/World Data 1227 1160 Arundel, S.T., 2005. Using spatial models to establish climatic limiters of plant Center for Paleoclimatology, NOAA/NCDC Paleoclimatology Program, Boul- 1228 1161 species' distributions. Ecological Modeling 182, 159–181. der, Colorado, USA. Chronology numbers Ca561, Ca562, Ca563, Ca564, Ca566, 1229 1162 Bailey, R.A., Dalrymple, G.B., Lanphere, M.A., 1976. Volcanism, structure, and Ca 567, Ca 568, Ca 569, Ca 570, Ca 571, Ca 572, Ca 573, Ca 574, Ca 575, Ca 1230 1163 geochronology of Long Valley Calder, Mono County, California. Journal of 576, Ca 578, Ca 579, Ca 580, Ca 581, Ca 582, Ca583, Ca 584, Ca 585, Ca 586, 1231 1164 Geophysical Research 81, 725–744. Ca 587, Ca 588, Ca 589, Ca 590, Ca 591, Ca 592, Ca 593, Ca 595, Ca 596, Ca 1232 1165 Benson, L., Kashgarian, M., Rye, R., Lund, S., Paillet, F., Smoot, J., Kester, C., 597, Ca 602, Ca 603, Ca 604, Ca 605, Ca 606, Ca 607 (J.C. King). 1166 Mensing, S., Meko, D., Lindstrom, S., 2002. Holocene multidecadal and ITRDB (International Tree-Ring Data Bank), 2005d. IGBP PAGES/World Data 1233 1167 multicentennial droughts affecting northern California and Nevada. Center for Paleoclimatology, NOAA/NCDC Paleoclimatology Program, 1234 1168 Quaternary Science Reviews 21, 659–682. Boulder, Colorado, USA. Chronology numbers Ca 528, Ca530, Ca535 (D.A. 1235 1169 Clark, D.H., Gillespie, A.R., 1997.UNCO Timing and significance of late-glacial and Graybill); Ca 533, (D.A. Graybill and V.C. LaMarche); Nv 519, Ca 605, 1236 1170 Holocene cirque glaciation in the Sierra Nevada, California. Quaternary Ca606, Ca633 (J.C. King); Ca630, Ca631 (D. Meko et al.). 1237 1171 Research 19, 117–129. Jackson, S.T., Overpeck, J.T., 2000. Responses of plant populations and communities 1238 1172 Cook, E.R., Holmes, R.L., 1992. Program CRONOL. In: Grissino-Mayer, H.D., to environmental changes of the late Quaternary. Paleobiology 25, 194–220. 1239 1173 Holmes, R.L., Fritts, H.C. (Eds.), International Tree-Ring Data Bank Program Kellogg, R.M., Rowe, S., Koeppen, R.C., Miller, R.B., 1982. Identification of 1240 1174 Library, User's Manual. Laboratory of Tree-Ring Research, Tucson (AZ). the wood of the soft pines of western North America. International 1241 1175 Cook, E.R., Kairukstis, L.A. (Eds.), 1990. Methods of Dendrochronology. Association of Wood Anatomists Bulletin 3, 95–101. 1242 1176 Kluwer, Dordrecht, Netherlands, 394 pp. Kinloch, B.B., Scheuner, W.H., 1990. Sugar pine. In, Burns, Russell M., 1243 1177 Critchfield, W.B., Little, E.L., 1966. Geographic distribution of pines of the and Barbara H. Honkala, (eds.), Silvics of North America: 1. Conifers; 2. 1244 1178 world. USDA Forest Service. Miscellaneous Publication, vol. 991. 97 pp. Hardwoods. Agriculture Handbook 654. U.S. Department of Agriculture, 1245 1179 Daly, C., Neilson, R.P., Phillips, D.L., 1994. A statistical-topographic model for Forest Service, Washington, DC, vol.2. 1246 1180 mapping climatological precipitation over mountainous terrain. Journal of Kleepe, J.A., in press. A study of ancient trees rooted 36.5 m (120′) below the surface 1247 1181 Applied Meteorology 33, 140–158 (http://www.orst.edu/prism/). level of Fallen Leaf Lake. Journal of Nevada Water Resources Association. 1248 ARTICLE IN PRESS

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1249 Konrad, S., Clark, D.H., 1998. Evidence for an early Neoglacial advance from of magmatic gas beneath , California. Journal of Geo- 1288 1250 rock glaciers and lake sediments in the Sierra Nevada, California, U.S.A. physical Research 103, 15303–15323. 1289 1251 Arctic and Alpine Research 30, 272–284. Stine, S., 1990. Late Holocene fluctuations of Mono Lake, Eastern California. 1290 1252 Kukachka, B.F., 1960. Identification of coniferous woods. Tappi 43, 887–896. Palaeogeography, Palaeoclimatology, and Palaeoecology 78, 333–382. 1291 1253 Li, H.C., Bischoff, J.L., Ku, T.L., Lund, S.P., Stott, L.D., 2000. Climate Stine, S., 1994. Extreme and persistent drought in California and Patagonia 1292 1254 variability in East- Central California during the past 1000 years reflected by during Medieval time. Nature 369, 546–549. 1293 1255 high-resolution geochemical and isotopic records from Owens Lake sedi- Stine, S., Wood, S., Sieh, K., Miller, C.D., Oct 12–14, 1984. 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UNCO