Sprouting and Seedling Establishment in Plains Silver Sagebrush (Artemisia Cana Pursh

Volume 50 | Number 3 Article 3

10-31-1990 Sprouting and seedling establishment in plains silver sagebrush (Artemisia cana Pursh. ssp. cana) C. L. Wambolt Montana State University, Bozeman, Montana

T. P. Walton Montana State University, Bozeman, Montana

R. S. White USDA, Agricultural Research Service, Fort Keogh Livestock and Range Research Station, Miles City, Montana

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Recommended Citation Wambolt, C. L.; Walton, T. P.; and White, R. S. (1990) "Sprouting and seedling establishment in plains silver sagebrush (Artemisia cana Pursh. ssp. cana)," Great Basin Naturalist: Vol. 50 : No. 3 , Article 3. Available at: https://scholarsarchive.byu.edu/gbn/vol50/iss3/3

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]. The Great Basin Naturalist PUBLISHED AT PROYO. UTAH, BY BRJGHAM YOUNC U~IVERSITi

ISSN 0017-3614

VOLU 1£ 50 31 OcroBER 1990 NO.3

SPROUTING AND SEEDLING ESTABLISHMENT IN PLAINS SILVER SAGEBRUSH (ARTEMISIA CANA PURSH. SSP. CANA)

l C. L. Wambolt', T. P. Walton , and it S. White:!

ABSTRA<..T.-The importance and nature ofvep;ctative reproduction was (,'Ompal'cd with seedling establishmtc>nt in plains siJvec sagebrush (A rlemisia co.rw Pursh. ssp. ainu). Sixty-three pt:r<''eot of plants CX(.-:lvated origin,lted from rhizomes. Sites that experienc-ed habitat disturbance did not have a signifi<:antly different numbcTofplants ori~inating from vegetative reproduction than did undisturbed sites. Parent rruwmes were significantlyoJder than taproots, which were significantly older than aboveground stems. Rhiwme system.~ were spread 3.3 times that of plant hcj~ht. Seventy-nine percent of rhizomatous daughter plants were 100 em or less from parent plants. Up to 52 sprouts were found on one rhizome. Seedling estahlishment was greatest durinF; wet gTOwin~ seasons, and vegetative reproduction was greatest during dry years.

Sagebrush (Artemisia L.) taxa are among for each taxon individually. The most perni the most important plants on rangelands cious weeds generally grow from under of the western United States (Beetle 1977). ground roots, rhizomes, and buds (Cook Plains silver sagebrush (Artemisia cana 1983); thus, these are important traits to un Pursh. ssp. cana) is a major consideration in derstand in successful rangeland taxa. Para the management of rangelands in the north doxically, vegetative reproduction in sage ern Great Plains. This is due to the taxon's brush taxa has not been previously studied in competitive nature with livestock forages and detail despite the importance of these taxa its importance as a habitat component for (Beetle 1977, McArthor and Plummer 1978) several wildlife species. Together wilh the and their obvious reproductive success (Har· other two subspecies of silver sagebrush, vey 1981). Understanding sagebrush repro mountain silver sagebrush (A. cana ssp. vis ductive success would provide insight into cidula [Osterhout)) and Bolander silver sage plant population dynamics throughout west brush (A. cana ssp. bolanderi [Gray] Ward), ern North Ame,;ca (Molt 1979). Our objective this complex is encountered on millions of was to assess the importance and nature of hectares in 13 western states and 2 Canadian vegetative reproduction (sprouting) versus provinces (Harvey 1981). seedling establishment in plains silver sage The literature (Young and Evans 1972, brush. Bostock and Benton 1979, Went 1979) pro vides contradictory evidence as to whether STUDY SITES DESCRIPTION seed or vegetative reproduction is more im portant for survival of plants displaying both Six study sites were selected in drainages habits in arid and semiarid environments. of the Tongue and Yellowstone rivers near Accordingly, this will have to be determined Miles City in southeastern Montana. The sites

IDell:ut'ntmt ofAllimal ~,\d !\ani/.e s...io:-n~....s. MOIlI:lna Slale Uni\'"uil~. Bro...·IlIIIl. \fonlanl 5971 i. ll:SDA.. Aj:,rk"hurl.1 flese:u<·h S",n·;rt. Fort J(~h Li"~IOI'k"lid R"Jl~c Kt''

WI 202 C. L. WAMBOLTETAL. [Volume 50 were considered typical in climatic and each excavated plant. Aging ofsagebrush was edaphic rdationships of plains silver sage feasible despite the difficulty created by com brush habitats in the northern Great Plains mon stem splitting and layering (Ferguson (Harvey 1981). Soils at each study site are 1964). texturally heterogeneous but are largely a mo To determine whether differences existed saic of 10alns, with silty clay loams predomi in the number ofsprouts to seedlings over the nant. Three sites (Yellowstone River-frigid six study sites, we conducted a paired Stu Ustic Torrilluvents, Lower Black Springs dent's t test (P < .025). A chi-square analysis mixed [calcareous] frigid Ustic Torrifluvents, (P < .05) was performed to learn if fire or and Lower Flood-fine montmorillonitic Bor ice action on three ofthe sites was significant ollie Camborthids) had experienced fire or ice in dctermining the ratio of sprouts to seed scraping and shearing in the preceding five lings compared with three undisturbed sites. years. No evidence of such disturbance was Analysis of variance (AN OVA) was used for found at the remaining study locations (Lig comparison of age and growth means among nite Creek-CaJIlborthid Torrifluvents, Paddy plant parts. Duncan's multiple range test pro Faye-fine montmorillonitic Borollic Cam tected by a prior F -test was used for compar bortbids, and Moon Creek-fine montmoril ing treabnent means. lonitic Borollic Natriargids). All sites have Isolated Plant Excavations received periodic cattle grazing. The area has an average annual precipitation of 340 Two large, well-established plants at the Lower Flood site were the subject of a com mm, with peak precipitation received in May plete root excavation, Plants were subjec¥ and June. tively selected based upon two criteria: (1) the plant had to be relatively isolated from other METHODS large plains silver sagebrush plants to mini Transect Excavations mize major competitive influences, and (2) there had to be an abundance of small plains At each study site a plains silver sagebrush silver sagebrush plants surrounding the po plant 16 to 40 cm in height was located at each tential pal'ent plant. The two plants selected 5-m interval along 25-m transects (4). Estab for excavation were slightly more than 1 m lished plants of this size were selected be in height. A 5-m area around each of the cause rhizomatous connections to parent large plants was excavated so that all roots, plants, ifpresent, were still readily apparent. including rhizomes ofall smaller plants, were The 20 plants located at each site were exca exposed. The size of each plant and the vated to determine whether they had sexual root wsb;hution from the excavations were or asexual origins. mapped to differentiate seedlings and Roots were carefully excavated by band so sprouts. Although we did not analyze the that fragile rhizome connections remained in data statistically, our direct observation of tact to determine if plants were of indepen the root networks facilitated interpretation dent origin or connected to another plant. oftbe transect data. Rhiwmes were generally found in the top 10 em of soil, while taproots were excavated to a RESULTS depth of1 m or an impenetrable layer. Plants without connecting rhizomes were consid Transect Excavations ered to have originated from seed. Plant Plants arising from rhizomes were more height, length of rhizomes, and stem and rhi abundant than those that grew from seedlings wme diameters were measured on all origi (P < .025) (Table 1). Approximately 63% ofthe nally located plants and those plants to which excavated plants were connected by rhizomes they were directly conneeted. Root distribu to an established plant or rhiwme system. tion from each excavation was mapped within Counts of annual rings established that the a grid, and line sketches of e.ach plant were rhizomatous connections were one to four drawn. Samples for age determination (Fer years old. Usnally, a large, established parent guson 1964) were taken from stem, root, rhi plant was the source of rhizomes connect· zome, and connecting rhizome sections of ing either single plants or a series of sprouts 1990] SPROlrllNG AND SEEDLING ESTABLISHMENT IN SAGEBRUSH 203

Subsurface Connecting Rhizo"J" d

Fig. L Graphic example ofan excavated sprout connected to a parent plant and other ofi'spJing. Original or oldest materjal is on far right.

TABLE 1. A comparison ofthe number ofrbiwmatous allording an advantage to taprooting plants in to nonrhizomatous plains silver sagebrush plants found at reaching deeper, more fuvorable conditions. each srudy site. The three sites disturbed by fire or ice action Study sitel were compared with the three undisturbed 1 2 3 4 5 6 Total sites to learn whether the ratio of sproul~ to Rhizomatous2 13 13 15 7 13 14 75a3 seedlings changed with disturbance. No sig Nonrhizomatous 7 7 5 13 7 6 45(, nificant dillereuces (P < .05) in numbers of ISite~ arc numbered a! follows: 1 Ycll()W~t(lne River, 2-l.owcr Bhu:k plants arising from rhiwmes due to dlstur Springs. 3-I..ower 1'1oooJ, 4-Lignita Creek. 5-Paddy l"flye. 6-Moon Creek. ban<..."e were found. lIPlnut5 with rhi%ome ootmections (alive or dead) (0 otherplants. :Jsigni6caot (P < .00..5) dilfcrCllC& between rhiMlUltous1IIl.d f)Qnrtlizom:J.touf Generally, an elaborate subsurface rhizome plant tlJIl;>!,s by Student's t f....t ::Ire 101klwed bydifferent lettcrli. system was found that was older than ahove ground stems. There were significant (P < (Fig. 1). However, some plants were frnID a .05) age differences among plant stems, tap series of sprouts along a rhizome presently roots, and parent rhizomes (Table 2) over all terminated with a dead or decadent stump. six study sites. Aboveground stems were One site, Lignite Greek, was different in that three to five years younger than taproots aud it had a majority of nonconnected individuals associated rhizomes. Parent rhizomes with di (Table 1). Reduction ofavailable soil moisture rectly conneeted sprouts were significantly due to clay pan soils overlying extensive older than taproots. Taproots and rhizomes gravel at Lignite Creek might explain the without direct connections to a parent plant difference. Plant water use would be less were not siguificantly different in age from fuvorable with this condition at the surface, each other. 204 C. L. WAMBOLT ET AL. [Volume 50

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N u m 20 ,., " ",'.-,.. ,.. , ,., .. , ,,,.•. ,,,,, ,, . ,.",,, "... ",.,.,-.,.,.".,..-",-.-"" .. ,., .•.. , ... "'".. ,,... , ""... ' ... ".'. b e r 10 ...... 9 .

0.1.-... 0-50 51-100 101-150 151-200 201 and over Centimeters

Fig. 2. Number of distances encountered between parents and traceable sprouts of rhizomatous plains silver sagebrush over six study sites.

TABLE 2. Age relatiollships ofabove- and belowground TABLE 3. Growth relationships of above· and below· parts ofplains silver sagebrush plants from the six study ground parts ofrhizomatous plainssilversagebrush plants sites. from the six study areas.

Mean age Standard Numberof Mean Range Number of Plant part (Years) deviation samples Plant part (em) (em) samples Stems 3.4') 2.0 204 Plant (sprout) height 32" 11-59 155 Taproots 6.9" 3.1 28 Lateral distance to Parent rhizome2 8.8'" 3.7 68 parent connectioni 78' 14·277 61 Rhizome system:,! 6.0b 2.5 128 Lateral spread of e 'SIW"ifocanl (P < .OS) mean di(f~lOeS by DW1ClUl'S mul~ t1lRge ICSI ..re rhizome system:,! 105 1l·J69 90 b11lJW\.od by diffi..,enl kt~. ISi{;Ilificent (P < .OS) mean diIkrell

•

1 1 1 NUMBERS IN ~1 HEICHT CATEGORY 2cr- ~ 5 45+ ern 14 • 35-"5 c:m 13 3 25-35 em 11 '\;. 1 15-~5cm 2. • 1 1 0-15 em •• 1 ----- rhizome aboveground .hoots 0 1 4@ ,,_nopy cova, or main plant I ; I 0 .5 ''''

Fig. 3. Diagram of an isolated plant excavation. All aboveground shoots are shown individually and numbered according to height. systems (Fig, 3). This was most apparent with management. Benefits of vegetative repro older, well-established plants from which the duction include (1) an enhanced ability to uti network originated (Fig. 3). lize unevenly distributed resonrces and (2) an Characteristic of the horizontal rhiwme increased competitive ability to occupy adja expansion were sizeclasses decreasing in con cent areas (Harper 1977, Cook 1983). In addi centric circles away from the parent plant. tion) sprouts are better able to resist invasions There was considerable variation in rhizome ofseedlings from otherspecies while reducing complexity within these individual systems. the probability of extinction. This is accom Excavations established that rhizomes can plished by spreading the risk among many sprout at least 3 m from the parent plant. genetically identical individuals (Cook 1983). Therefore, a large number .of progeny may arise asexually from one individual. Individ An evolutionary strategy that employs asexual ual rhizomes had from 1 to 52 sprouts. mechanisms is consistent with the findings of o evidence indicated that all individual Abrahamson (1980), who reported that in systems were of the same origin. That is, no creased environmental severity generally common root connections could be traced. shifted emphasis to vegetative reproduction. However, some might have been connected Generally, vegetative reproduction is most and later separated after mortality ofconnec important where fire, weather phenomena, tive rhizomes. and other disturbances are common (Bostock and Benton 1979, Went 1979, Abrahamson DISGUSSION 1980, Legere and Payette 1981). The sprout Vegetative reproduction is prevalent in ing nature of plains silver sagebrush is likely plains silver sagebrush, and the causal agents an adaptation to its northern Great Plains are of interest and importance to rangeland habitat. Flooding with associated deposition, 206 C. L. W AMBOl.T ET AL. [Volume 50 along with ice scraping dUring winter events, of plains silver sagebrush reproduction is is common. Plant prodnction and subse strongly related to available moisture as in quently fuel loads for fires are relatively dicated by Salisbwy (1942) for wild garlic high in bottomlands inhabited by the taxon. (AUium ca,;natum L.). Perbaps this influence Consequently, fires are common in plains ofclimate on reproduction might mask differ silver sagebrush habitats. It is logical tllat ences of sprout-to-seedling ratios expected plains silver sagebrush is a vigorous sprouter between disturbed and undisturbed sites. In in response to the evolutionary influences our study, these ratios did not vary signifi of recurring disturbances. This taxon is re cantly (Table 1). The reproductive strategies ported to produce only 18% as many achenes ofplains silver sagebrush partially explain the as big sagebrush (Artemisia tridentata Nutt.) taxon's success and require consideration in (Harvey 1981, Tisdale and Hironaka 1981), managing its habitats for optimum balance which likely reflects a reliance on asexual re between livestock forage production and suit production. able wildlife habitat. Abundant herbaceous vegetation in mesic flood plains produces substantial competition CONCLUSIONS for seedlings. Vegetative sprouts may com pensate through more rapid morphological We conclude that vegetative reproduc development. Because sprouts have the ad tion in plains silver sagebrush is the pri vantage ofa nutrient reserve from established mary means ofplant establishment. Although plants. the sprouting strategy increases sur sprouting in this taxon has likely evolved with vival (Abrahamson 1980). babitat disturbances, tbis study did not estab Although not rare in the communities stud lish that a greater percentage ofplants arising ied, seedling establishment was found in only from sprouts should be expected on disturbed one-third of the plants excavated (Table 1). than on undisturbed sites. However, annual This may be attributable to the inconsistency precipitation does appear to be related to the ofspecific environmental conditions required relative success in initiation and survival of for germination and seedling establishment. seedlings and sprouts. Seedlings apparently Environmental factors, especially drought, require more moisture for both germination might best explain differences in ratios of and survival than do sprouts. sprouts and seedlings found in 1983. For ex ample, a three-year drought at the study area ACKNOWLEDGMENTS occurred between 1979 and 1981 when the mean annual precipitation was 23.0 em and This paper was published with the approval preceded the wet year o£1982 with 41.6 em of ofthe Montana Agricultural Experiment Sta precipitation. The long-term average precipi tion as Journal Article J-2431. tation is 34.8 em. This drought coincided with the ages ofmost plants examined in this study. LITERATURE CITED The relatively moist years preceding (1978 with 44.7 em) and following (1982 with 41.6 ABRAR-\MSON', W. G. 1980. Demography and vegetative em) this drought provided the periods of es reproduction. Pages 89-106 in O. T. Solbrig., ed.. tablishment for seedlings at the study sites. Demography and evolution in plant populations. Blackwell Scientific Publications, Oxford. However, just as seedlings appear favored BEETLE, A. A. 1977. Recognition of Artemisia 5ubspe during wet years, sprouts were found to have cies-a necessity. Pages 35-42 in K. L. Johnson, the advantage in establishing during rela ed., Proceedings, 6th Annual Wyoming Shrub tively dry periods. The cool, wet growing sea Ecology Workshop. son of1982 was followed by a warm, dry (22.3 BOSTOCK. S. J....\1\:0 R A. BENTON. 1979. The reproductive strategies of five perennial Compositae. Journal of em) growing season in 1983. Subsequently, Ecology 67, 91-107. numerous seedlings and few sprouts were COOK, R E. 1983. Clonal plant populations. American produced during 1982, and few seedlingswith Scientist 71: 244-253. an abundance of sprouts were produced in FERCUSON, C. W. 1964. Annual rings in big sagebrush. 1983. Few seedlings from 1982 survived Universit}'of Arizona Press, Tucson. 95 pp. HARPER, J. L. 1977. Population biology of plants. Aca· beyond the dry second season. Therefore, it demic Press, London, New York, San FranciSCQ. appears that both the mode and the success 892 pp. 1990] SPROUTING AND SEEDLING ESTAllLlSHMENT IN SAGEBRUSH 207

HARVEY, S. J. 198L Life history and reproductive strate tional Biological Program. VoL I. Cambridr;e Uni· gies in Arlemi.~ia. Unpublished master's thesis, versity Press. Camhridge. London, New York. Montana State University, Bozeman. Melbourne. LECEIlF.:, A., AND S. PAVt.lTE. 1981. Ecology of black SAI.ISBURY. E. J. 1942. nereproductivecapacity ofplants: spruce (Picea mariana) clonal populations in the studies in quantitative biology. G. Bell and Sons, hemial'ctic zone, northern Quebec: population Ltd.. London. 224 pp. dynamics ao.d spatial development. Arctic and TlSDALB, E. W .• AND M. IIlRONAKA. 1981. The sagebrush· Alpine Research 13: 261-276. grass region: a review of the ecologicallitcmture. MC.~RTHUR, E, D.. AND A. P. PLUMMER. 1978. Biogeogra University of Idaho, Forest, Wildlife and Range phy and management of native western shrubs. A Experiment Station Bulletin 209. 31 pp. case study, section Tridentatae of Artemisia. WENT, F. W. 1979. Gennination and seedling behavior of Pages 229-243 in K. T. Harper and J. L. ReveaL desert plants. Pages 477-479 in Aridland ecosys eds., Proceedings, Intermountain Biogco!:-'Taphy tems: strudure. functioning, and management. Symposium. Great Basin Naturalist Memoirs International Biological Program. Vol. 1. Cam No.2, Brigham Young University Press, Provo, bridge University Press. Cambridge. London, Utah. 268 pp. New York. Melbourne. MOTI, J. J. 1979. Flowering, seed formation, and dis YOUNG, J, A.. AND R. A. EVANS. 1972. Population dynamics persaL Pa~es 627-645 in Aridland ecosystems: ofgreen rabbitbrush. Proceedings Western Soci strut:ture. functioning and management. Intcrna- ety Weed Science 24: 13.