Great Basin Naturalist

Volume 56 Number 4 Article 2

11-21-1996

Stem growth and longevity dynamics for Dorn

Vicki L. Taylor Brigham Young University

Kimball T. Harper Brigham Young University

Leroy L. Mead Brigham Young University

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Recommended Citation Taylor, Vicki L.; Harper, Kimball T.; and Mead, Leroy L. (1996) "Stem growth and longevity dynamics for Salix arizonica Dorn," Great Basin Naturalist: Vol. 56 : No. 4 , Article 2. Available at: https://scholarsarchive.byu.edu/gbn/vol56/iss4/2

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Great Basin Naturalist 56(4), © 1996, pp, 294-299

STEM GROWTH AND LONGEVITY DYNAMICS FOR SALIX ARIZONICA DORN

Vicki L. Taylorl , Kimball 1: Harperl , and Leroy L. Meadl

AllSTHAGI:-Diameter-age relationships of Salix arizonicu. ( ) stems were investigated for 5 populations on the Markagunt, Paunsaugunt, and Sevier plateaus in southern and central . Of the 430 stems studied, none exceeded 26 mm in diameter at ground level (estimated age of 19 yr). Equations developed for predicting age from stem diameters consistently accounted for over goo.,f, of the observed variation. Slopes of predictive equations were homoge­ neous across the 3 sites considered in detail. At 2 sites 46% and 38% of the stems exceeded 10 mm (-7 yr old) diameter at ground level. At a 3rd site, no stems survived to exceed that size. Stem-age profiles at specific sites may thus be useful f<)r assessing the relative fuvorability oflocal environments for the species.

Key words: Arizona willow, Salix, st.em. diameter, dendrod~ron()logy, southern Utah.

The purpose ofthis study was to assess stem 1987). studies have detailed the effects diameter-age relationships in Salix arizonica of variations in available moisture on (Arizona willow), a species so rarc that routine growth in specific habitats or provided infor­ severance of stems for aging cannot be justi­ mation for interpreting archaeological prob­ fied, Our objective was to develop a stem-age lems, Ring counts have also been used to pre­ prediction model based on stem basal diame­ dict stem diameter-age relationships in predic­ ters. Ultimately, we desfred to accurately esti­ tive models for interpreting site quality for var­ mate stem age at a broad range of ecological ious species or for clarification of successional situations without sacrificing stems, We also patterns in vegetation that includes many woody evaluate the possihility of using stem-age pro­ species (Brotherson et aI. 1984, 1987). files at an array of sites to determine their rela­ tive favorability for growth of S. arizonica, THE SPECIES AND ITS DISTRIBUTION

DENDROCHRONOLOGY AS A TOOL Salix arizonica is small. Rarely do stcms ex­ ceed 1,0 m in height. The species occurs in such Growth rings of trees and shruhs have been dense carpets of other species (both vascular used for m,my decades for aging stems and and nonvascular) that reproduction via its tiny, dating past climatic events (Douglas 1935, wind-dispersed seeds appears to be uncom­ Glock 1937). Growth rings are also used to mon, Accordingly, the species apparently per­ establish unique sequences of good and poor sists at occupied sites primarily by vegetative years that permit dating nonliving tree frag­ reproduction. In the process, what appear to ments used in prehistoric human structures he large clones (as much as 10 ill across) may (Schulman 1956, FrillS 1971, Stockton and develop. Meko 1975, Harper 1979). Ring-width varia­ Salix arizonica occurs in 2 disjunct locations tions are often used to assess differences in the in the Intermountain West. The species was favorahility of various environments for the first discovered on the White Mountains of growth of selected species (Ferguson and east central Arizona by Carl-Eric Granfelt in Humphrey 1959, Frills 1962, Stockton and 1969 (Galeano-Popp 1988). Robert Dorn (1975) Fritts 1973, Frills 1974). Although these stud­ used ho!otype specimens collected by Granfe!t ies have focused mainly on trees (Glock 1955, to describe the species in 1975. In November Argeter and Glock 1965), some have dealt with 1992, unaware that the species occurred in shrub species (Ferguson 1958, 1959, Ferguson Utah, the U.S. Fish and Wildlife Service pro­ and Humphrey 1959, Brotherson et a!. 1984, posed S, arizonica for listing as endangered with

ID"pltrtlm:nt of Botany 11Ild Ran~" S"ienee, Brigham Young UIliversIly, Provo, UT 84602.

294 1996] ARIZONA WILLOW STEM GROWTH 295 designation of critical habitat (Atwood 1995). tally intermediate (Lowder Creek) as well as In June 1993 a previously misidentified herb­ extreme environmental conditions for S. ari­ arium specimen ofS. arizonica was discovered; zonica in Utah. The Rainbow Meadows sHe it bad been c-ollected on the "Sevier Forest" occurs on acid soils at near maximal elevations (now Dixie National Forest) in 1913. During for the species, while the East Fork of the June 1994, 5. arizonica was discovered on the Sevier River population occurs on aUuvium Markagunt Plateau near Brianhead resort area. derived from C'ellcareous substr.1tes at the low­ Subscquent searching revealed a small popula­ est elevation known for the species. tion on the Paunsaugunt Plateau and 2 more Depth of peat layer was determined at each farther nurth on the Se,~er Plateau (Mead site hy digging pit, to expose soil profile. (Mead 1996). Following this "rediseovery" of S. ari­ 1996). At Lowder Creek, Sheepherder Camp, zonica in Utah, USDA Forest Service, USDr and Sevenmile Creek, depth to water table w,," Fish and Wildlife Service, and USDI National dete'mined by opening a hole approximately 1 Park Service officials cooperated in developing m deep with a 1.27-em-diameter pointed rod, a conservation agreement and strategy that then inserting a O.64-cm-diameter wooden outlines the "actions, costs and skiUs needed to dowel into the hole to me""ure depth to water. implement protective measures and research This measurement was taken at each plant sam­ studies needed lor the species" (Atwood 1995). pled and an average value was computed f()r As a result of the conservation agreement and each site. Dcpth to water table at Rainhow stmtegy, which documents loog-term plans for Meadows was determined by measuring dis­ conservation of S. arizonica, the Fish and \i\'ild­ tance from soil surface to Welter table surface in life Service withdrew their proposed rule to a soil pit (Mead 1996). Depth to water table list the species a., endangered (Arizona Willow was determined at the East Fork site by mea­ Interageney Technical Team 1995). suring distance {'Tom the soil surhlce to the sur­ Although the species is locally ahundant ncar face of water running in the creek. This mea­ Brianhead, its total range is small in both Ari­ surement was taken at each S, arizonica clone; zona and Utah, and populations rarely include the mean distance is reported in Table 1. Depth more than a few score . This rarity seems ofpeat layer and depth to water table are vari­ related to the plant's preference for an uncom­ able among the study sites, with the Rainbow mon habitat: it grows preferentially on igneous Meadows site having the highest water table soils in cold, wet sites. In addition, in the White and greatest peat depth (Table 1). Y!ountains, management has favored conifers Two other populations of S. arizonica are con­ that reduce flow in riparian systems, leading sidered in this report. Populations at Sheep­ to poor drainage as watenvays become peat­ herder Camp, Sevenmile Creek, and Lowder choked. Such tmvironments become poorly aer­ Creek have been sampled to establish stem­ ated and less suitable habitat for S. arizonica. diameter prome. based on samples nf many Heavy use by elk has also adversely affected randomly chosen stems (154, 104, and 130 the species in Arizona (Arizona Willow Iotenl­ stems, respectively, sampled at the 3 forcgoing geney Technical Team 1995). This study has sites). No stems were severed for aging at the been confined to the Utab populations of Salix Sheepherder or Sevenmile sites. arizonica (Fig. 1), hut we have attempted to The Rainbow :Meadows site is approximately sample the full range of conditions associated 1.6 k-m south and slightly cast ofBrianhead Peak with the species in our study area, at approximately 3155 m elevation (37'40' , 112·56'W). Suils are derived from tertiary vol­ METHODS AND STUDY AREAS canics with a histosol surface horizon (Mead 1996). The Lowder Creek population is approx­ Ibe diameter-age data for S. arizonica were imately 4 km east and slightly soutb of llJ"ian­ collected from 3 populations: 2 on the Cedar head Peak (37'41'N, 112·48'W). Soil at this City Ranger District and anotller on the Powell site is developed from tertiary volcanic mater­ Ranger District, Dixie National Forest (Fig. 1). ial below an alluvium surface layer (Mead The Rainhow Meadmvs, Lowder Creek, and 1996). The East Fl'rk population, approximately East Fork oftbe Sevier River populations were 48 km from the Lowder populatioo (37'26'N, chosen because they represent cnvironmen~ 112'21'W), is at the lowest elevation knowo for 296 GREAT BASIN NATURALIST [Volume 56

&0" Eld•• Cache '-,r'- lich UTAH

Too,l, ""'mil

Solt to!<.

Juob ... Corbon Millo,d Em.ry Grond

Pillt. Woyn.

I,on

.E Kone

Fig. L A, Rainbow Meadows; B, Lowder Creek; C, Sheepherder Camp; D, Sevenmile Creek; E, East Fork of the Sevier River.

this species in Utah. This population grows on stem closest to the random point in each of 5 alluvium from the Claron Limestone Forma­ size-classes was collected in each of 3 quad­ tion with an organic surface horizon (Mead rants (the right rear quadrant was not sampled). 1996). Stems were severed at ground level using wire Commonly associated plants at the sites sam­ cutters or a small hand saw. The diameter­ pled include , Polygonum histor­ classes sampled were 0-5 mm, 5.1-10 mm, taides, Aconitum columbianum, micro­ 10.1-15 mm, 15.1-20 mm, and >20 mm at ptera, Geranium richardsonii, Geum macro­ ground level. Thus, 3 stems per size-class were phyllum, and (Mead sampled at each site. Due to the low density of 1996). As Mead (1996) has shown, the relative S, arizonica at the East Fork site, quadrants abundance of these species varies from site to were not used. Stems were collected from all site depending on such variables as soil temper­ S. arizonica clones inside a livestock-grazing ature, depth to water tahle, and soil reaction. exclosure in the study area. No stems could he Fifteen randomly chosen stems were sam­ fonnd at this site for the>20 mm size-class, so pled at each site at the Rainhow and Lowder only 12 stems were sampled. locations. At each site 4 quadrants were estab­ Stem samples were laheled, placed in indi­ lished around randomly chosen points. The vidual hags, and taken to the lab. Stem hases 1996] ARIZONA WILLOW STEM GROWTH 297

TABLE 1. Environmental conditions at 5 Salix oriumica sites. Water table was taken at aU plants sampled wherever soil stoniness pennitted insertion of the doweL to water depth. At East Fork water deplh. was based on only 16 points because only 16 plants exist at that site. The measure ofvariance around W-d.teT table mean depth is standard error.

Site Elevation Soil pH Soil temp. @ 1·Jean depth to Peat depth (m) SO-em dep.h (0C) water table (em) (em)

Rainbow 3155 5.15 8.30 (Septembe,) 5.1 ± NA 32 Lowder 3139 5.79 W (August) 45.5 ± 1.81 o Sheepherder 3130 5.72 6° (Augu,') 44.4 ± 1.60 44 Sevenmile 2789 6.38 10° (August) 10.5 ± 1.12 o East Fork 2536 7.61 16° Ouly) 46.5± 6.89 o

T.>\BLE 2. Regression equations relating stem diameter to age of Salix arizcmica stems taken from 3 different sites. The regression equation for all sites combined is also shown. In the equation the independent variable, X, represents stem diameter (in mm). The symbol Y represents estimated age of any given stem. Site No. of Equation R' Significance stems level

Lowder 15 y ~ -0.42 + 0.82X .953 0.01 Rainoow 15 y ~ -0.28 + 0.78X .950 0.01 East Fork 12 Y ~ -1.40 + 0.71X .910 0.01 All 3 sites combined 42 Y ~ -0.99 + 0.81X .926 0.01

were sectioned diagonally and sanded with fine mator equation developed for each site to pre­ sandpaper; growth rings were counted twice dict age of collected from the other 2 (once by each of 2 observers) with the aid of a sites (i.e., Rainbow equation used to test Low­ stereoscopic microscope (Brotherson et aI. 1987). der and East Fork samples, Lowder equation Diagonally cut surfaces permitted growth rings used to test Rainbow and East Fork samples, to be identified with greater confidence. Sanded etc.). These analyses demonstrated that esti­ sunaces sometimes had to be polished with mated ages for any equation-test site combina­ immersion lens oil to enhance ling visibility. tion were always strongly correlated with actual Each growth ring was assumed to represent I age (R2 always > .90). In these analyses no yr's growth. Linear regression was used to stems were found to differ from predicted age quantifY stem diameter-age relationships. based on diameter by more than 3 yr, and most stems (>90%) differed by less lhan 2 yr (Fig. I). RESULTS An application of the age-estimator equa­ tion is shown in Figure 3. As part of the yearly S. arizoni(;Q, stems from the 3 sites at which monitoring program, basal diameters of S. ari­ stems were cut and aged ranged in basal diam­ zonica were taken for a large sample of stems eter from 2 to 26 rom and in age from I to 19 at each of 3 sites: Sheepherder Camp, located yr. Stem diameters (rom) were plotted against approximately 8 km south ofBrianhead Peak at stem age (yr), and regression equations were 3130 m elevation (37 0 37' ,1l2'56'W); Sev­ generated (Table 2). Slopes for regression enmile Creek, II km north of Fish Lake in the equations from the 3 sites were tested for simi­ Fishlake National Forest, Loa Ranger District larity using methods described in Snedecor at 2789 km elevation (38°39'N, III °40'W); and Cochran (1967) and were found not to dif­ and Lowder Creek (described above). At each fer significantly (P > 0.50). Thus, data from all ofthese sites, ti,e numbers ofstems within each sites were pooled to produce a single equation diameter-class were tabulated and are reported (Y = -D.99 + 0.8IX) for subsequent use in as percent oftotal stems in each size-class. The estimating age (Y) from diameter (X) (Fig 2). results (Fig. 3) demonstrate large differences in As a further test of the validity of pooling stem-diameter profiles among the 3 sites. At data from all sites, we used the individual esti- Sheepherder Camp over 4% of the stems are 298 GREAT BASIN NATURALIST [Volume 56

20,------,----, or Sevenmile Creek. Alternatively, the results y", -0.99 + O.81X may indicate that willows are less severely R2 = 0.926 • browsed by ungulate grazers at Sheepherder Camp than at the other 2 sites. Since ungulate exclosures were not erected at these sites until fall 1994, data are currently too limited to dis­ :s 10 tinguish between these alternatives. ~ • DISCUSSION

• The regression equation created from the pooled data of all 3 sites should be useful for o+-"'----~-~---~-----< predicting ages of S. ari.zonica from any knO\ivn o 10 20 30 Utab location using only basal stem diameters. Basal Diameter (mm) The equation should be useful for many pro­ jects in which stem age is desired but stems Fig. 2. Stem basal diameter-age relationships of S. ari­ cannot be sacrificed. For example, the ability to zonica on the Markagunt and Paunsaugunt plateaus of estimate age of stems accurately from basal southern Utah. diameter may permit scientists studying the species to correlate stem ages and stem~age larger than 20 mm diameter at ground level. profiles witb site conditions without destroying However, less than 1% of the stems at Lowder individual stems. Creek exceed that diameter, and at Sevenmile The results of this study demonstrate little Creek no stems have survived to become 10 variation in stem growth rates for S. arizonica mm in diameter. These results suggest that over a wide range of elevations and parent Sheepherder Camp is a more favorable site for materials (Table 1). That result suggests that the growth ofthe willow than either Lowder Creek species occupies but a narrow range of habitat

100.,.------,

80 Stem Diameter Class • 0-5mm 60 III 5.1-10 mm % of All IIiI 10.1-15 mm Stems ~ 15.1-20 mm 40 D 20.1-25mm III >25mm

20

o-l- Lowder Sheepherder Sevemnile

Site

Fig. 3. Comparative stem diameter distributions for sites for which a large, random inventory of stem diameters was available. 1996] ARIZONA WILLOW STEM GROWTH 299

situations within its overall geographic range. BHOTHERSO:N, J. D., J. G. CAI\\1AN, AND L. A. SZYSKA. 1984. Occupied sites almost always appear to have Stem-diameter age relationships of 7i1marix ramosis­ sima in central Utah. Journal of Range Mlmagement been modified by biological processes that 37,362-364. result in peat deposition and development of a BHOTHF.RSON, J. D., K. l~ PRICE, AND L. O'ROUHKE. 1987. rooting zone that is somewhat isolated from Age in relationship to stcm circumfcrence and stem the unaltered geologic substrata at the site. diameter in diITrose (Cowania mexicana var. stans­ Stem-age profiles should permit managers buriarw) in central Utah. Great Basin Naturalist 47: 334--.138. to identify sites where performance (stem sur­ DORN, H. D. 1975. A systematic study of Salix section Cor­ vival and/or reproduction by seed or rhizome) dalae in Nmth America. Canadian Journal of BobillY of the willow is above or below regional aver­ 53,1491-1522. ages. Such data would help managers deter­ DOUGLAS, A. E. 1.935. Climatic cycles and tree growth L a study of the annual rings of trees in relation to cli­ mine whether growth and reproduction of the mate and solar activity. Carnegie Institute of Wash­ species could be enhanced by reduction ofuse ington, Publication 289. Volume 1. Washington, DC. by browsers. To assist managers with such deci­ FERGUSON, C. W W58. Growth rings in big sagehrush as a sions, fenced areas that exclude domestic and possible aid in dating archaeological sites. Pages 210­ wild ungulate browsers have been erected at 211 in A. E. Dittert, Jr., editor, Hecent developments in Navajo Project salvage archaeology. EI Palacio 65: Lowder Creek, Sheepherder Camp. and on the 201-211. East Fork of the Sevier. An additional exclo­ __~ .. 1959. Growth rings in woody as potential sure will be built at Scvenmilc Creek in 1996. aids in archaeological interpretation. Kiva 25: 24-30. The U.S. Forest Service intends to continue FEHGl;SON, C. w., AND H. R. IIU\1PHREY. 1959. Growth rings on big sagebrush reveal rainfall records. Progressive monitoring Salix arizonica populations through­ Agriculture in Arb:ona 11: 3. out its range to learn about factors that influ­ FHITIS, H. C. 1962. The relation of growth ring widths in ence growth, reproduction, and stem survival. American beech and white oak to variations in cli­ Data from grazing exclosures will reveal the mate. Tree-Ring Bulletin 25: 2-10. extent to which browsing controls stem size __~. 1971. Dendroclimatology and dendroecology. Quaternary Research L 419-449. and longevity. The extent to which the abiotic __~.. 1974. Relationships ofring widths in arid-site coni­ environment limits stem growth and seed pro­ fers to variations in monthly temperature and precip­ duction can be more readily separated from itation. Ecological Monographs 44: 411--440. the effects of browsing now that animal exclo­ GALEANO-POPY, R. 1988. SaUx arizonica Dom on the Apache­ Sitgreaves National Forest: inventory and habitat sures have been constructed. study. USDA Forest Service, Apache-Sitgreaves National Forest, Contract 43-8173-8-687. 46 pp. ACKNOWI.EDGMENTS CLOCK, W S. 1937. Principles and methods of tree-ring analysis. Carnegie Institute of\Vashingtull, Publication We thank Ron Rodriguez for financial and 486. Washington, DC. 100 pp. __-,c' 1955. Tree growth II. Growth rings and climate. moral support for this project. Julie 'TI,lman Botanical Review 21: 73-188. provided invaluable assistance in the field and IIARPElI, K. T. 1979. Dendrochronology-dating with tree lab. This work was completed in part with rings. In ''\Z M. Hess and R. T. Matheny editors, Sci­ funds provided by the U.S. Forest Service. ence and religion: toward a more useful dialogue. Volume 1. Paladin House Publishers, Geneva, IL. MEAD, L. L. 1996. Habitat characteristics ofArizona willow LITERATURE CITED in southwestern Utah. Unpublished master's thesis, Brigham Young University, Provo, UT. ARGETER, S. R, AND W. S. GLOCK. 1965. An annotated bib­ SCHULMA::-I, E. 1956. Dendroclimatic changes in semi-arid liography oftree growth and growth rings, 1950-1962. America. University of Arizona Press, '11.1cson. 142 pp. University ofArizona Press, Tucson. 180 pp. SNEDECOR, C. '''I., AND W. G. COCHRAN. 1967. Statistical ARIZO::-lA WiLLOW INTERACENCY TECHNICAL TEA ....!. 19915. methods. Iowa State University Press, Ames. 593 pp. Arizona willow conservation agreement ffild strategy. STOCKTON, C. W, AND II. C. Fl\rrrs. 1973. Long-term recon­ U.S. l'orest Service, Intermountain Region, Ogden, struction of water level changes for Lake Athabaska UT; US. Forest Service, Southwest Region, Albu­ by analysis oftree rings. Water Resources Bulletin 9: querque, N:\1; National P,rrk Service, Rocky Moun­ 1006-27. tain Region, Denver, CO; US. Fish and Wildlife Ser­ STOCKTON, C. W, AND D. M. MEKO. 1975. A long-term his­ vice, Mountain-Prairie Region, Salt Lake City, UT; tOIY of drought occurrence in we.~tern United States US. Fish and Wildlife Service, Southwest Region, as inferred from tree rings. Weatherwise 28: 245-249. Albuquerque, NM. ATWOOD, D. 1995. Where have all the Arizona willows Receieed 15 March 1,9,96 gone? Sego Lily (Newsletter ofthe Utah Native Plant Accepted ,') July 1996 Society) 18: 3.