Great Basin Naturalist Volume 53 Number 2 Article 15 6-4-1993 Full Issue, Vol. 53 No. 2 Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation (1993) "Full Issue, Vol. 53 No. 2," Great Basin Naturalist: Vol. 53 : No. 2 , Article 15. Available at: https://scholarsarchive.byu.edu/gbn/vol53/iss2/15 This Full Issue 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]. T H E GREATR EAT BASINbaab7a S I1 N MTURALISTNA afufta FISTlyom llemoe ak VOLUME 53 n2na 2 JUNE 1993 BRIGHAM YOUNG university GREAT BASIN naturalist editor JAMES 11 BARNES 290 MLBM brigham young university provo utah 84602 associate editors MICHAEL A BOWERS BRIAN A MAURER blandy experimental farm university of department ofzoology brigham YoungyounguniversityyoungiuniversityUniversity virginia box 175 boyce virginia 22620 provo utah 84602 J R CALLAHAN JIMMIE R PARRISH museum of southwestern biology university of BIOWESTBIO WEST inc 1063 west 1400 north logan new mexico albuquerque new mexico utah 84321 mailing address box 3140 hemet california 92546 PAUL T TUELLER department of range wildlife and forestry JEANNE C CHAMBERS university of nevada reno 1000 valley road USDA forest service research university of ne reno nevada 89512 vada reno 920 valley road reno nevada 89512 ROBERT C WHITMORE JEFFREY R JOHANSEN division of forestry box 6125 west virginia uni department of biology john carroll university versityhersityversity Morganmorgantowntown west virginia 26506 6125 university heights ohio 44118 PAUL C MARSH center for environmental studies arizona state university tempe arizona 85287 editorial board richard W baumann chairman zoology H duane smith zoology clayton M white zoology lerran T flinders botany and range science william hess botany andan rangedRange science all are at brigham young university ex officio editorial board members include clayton S huber deandeanideann college of biological and agricultural sciences norman A darais director university publications james R babesbamesbarnes editor great basin naturalist the great basin naturalist founded in 1939 is published quarterly by brigham young university unpublished manuscripts that further our biological understanding ofthe great basin and surrounding areas in western north america are accepted for publication subscriptions annual subscriptions to the great basin naturalist for 1993 are 25 for individual subscribers 15 for student and emeritus subscriptions and 40 for institutionsin outside the united states 30 20 and 45 respectively the price of single issues is 12 all back issues are in print and available for sale all matters pertaining to subscriptions back issues or other business should be directed to the editor great basin naturalist 290 MLBM brigham young university provo UT 84602 scholarly exchanges libraries or other organizations interested in obtaining the great basin natu- ralist through a continuing exchange ofscholarly publications should contact the exchange librarian harold B lee library brigham young university provo UT 84602 editorial production staff joanne abel technical editor jan spencer assistant to the editor natalie miles production assistant copyright 0 1993 by brigham young university ISSN 001736140017 3614 official publication date 4 june 1993 5935 93 750 4946 the great basin naturalist PUBLISHED AT PROVO UTAH BY BRIGHAM YOUNG university ISSN 001736140017 3614 VOLUME 53 30 JUNE 1993 NO 2 great basin naturalist 532 appp 97 106 DEPLETION OF SOIL MOISTURE BY TWO COLD DESERT bunchgrassesBUNCH GRASSES AND EFFECTS ON photosynthetic performance jay E andersonAnderandersoniandereonisoni and nancee L toftatoft2tofttoht ABSIRACI this study compared the abilities of two cool season bunchgrassesbunchbuncherbunchgrgrassesasses to extract moisture from a drying soil and compared photosynthetic and stomatal responses of the two species as soil moisture supplies were depleted when grown in 49491 L pots in a greenhouse laymusleymus cinereus extracted more water from the sodsoilsoli and maintained higher gas exchange rates to lower absolute amounts otof soil water than did agropyron desertorumdesertorum the soil water content at the lower limit of extraction was 10310 3 for L cinereus and 13313 3 for A desertonondesertorumdesertonontorum when soil moisture was expressed as estrextractableextr actable soil water there was little difference between the species in pattern of water use both species maintained high stomatal conductances gw and photosynthetic rates A until extractable soil moisture was reduced to about 15 for field grown plants undertinderlinder severe watelwater stress A was higher in L cinereus than in A desertorumdesertortondesertorumtorton at comparable leaf watelwater potentials the relationship between A and gw was similar for the two species the higher A in L cinereus was a consequence of higher ggw thus higher A in L cinereus is achieved through some sacrifice of water use efficiency keykegkeywordswords extractableeftievti actable soil water leafwaterleafleak water potential stomatal conductance water use efficiency leymuslaymus cinereuscinereouscinereus agropyron desertorumdesertorurndesertorum plant species vary widely in their tolerance comstock and ehleringer 1984 ehleringer and of seasonal drought and in the mechanisms they cook 1984 delucia and heckathorn 1989 use to cope with declining supplies of soil mois- chaves 1991 as well as changes in the diurnal ture some species tolerate seasonal drought by patterns of gas exchange schulzeSchuize and hall maintaining high leaf water potentials through 1982 tenhunen et al 1987 it clearly would be stotstorstomatalnatal closure turner 1979 although they advantageous for such species to maintain pho- may maintain a high photosynthetic capacity totosynthetic rates as high as possible as soil and low stomatal conductance asliadliwill severely restrict plant water potentials decline carbon gain under prolonged drought in con- As plants extract water from a drying soil the trast other species allow their leaf water poten- amount ofplant available water decreases expo- tials to drop as soil water potentials decline nentially with decreasing water potential eg turner 1979 this enables the plant to con slatherslatyer 1967 fig 333.3 consequently the vol tinuedinue to extract water from a drying soil but ume of water gained by a plant in drying a given decreases in leaf water potential typically are volume of soil to 202.0 mpa over that gained in accompanied by decreases in photosynthetic ca- drying a soil to 151.5isls mpa for example is so pacity and stomatal conductance jones 1973 small that it would seem rather negligible in I1 departnientdepirtrnentofof biologicbiological il sciences idahoidabo state university patelloP atello 1daho83209idahoidabo 83209 012011O 11 fifth street apt 2cac davis californiailifoi 95616 97 98 GREAT BASIN naturalist volume 53 terms of total carbon gain jordan and miller preliminary gas exchange data from field grown 1980 and jordan et al 1983 estimated that plants J anderson unpublished data sug- the additional water made available to a crop as gested that L cinereuscicinereousnereus plants maintained higher a consequence of lowering leaf water potential photosynthetic activity and had higher stomatal 11 a few bars would support transpiration only for conductance at low leaf water potentials than 3 or 4 days in the absence of additional root did A desertorumdesertorum plants to test those pospossibilisibili growth thus there would seem to be little ties we conducted a greenhouse experiment 1 advantage in making the necessary osmotic ad to compare photosynthetic and stomatal re- justment andor other leaf modifications to tol- sponses of these two species to drying soil and erate very low water potentials and we might 2 to compare the lower limit of extraction of expect little difference among drought toleranttoletoierant the two species in addition we compared pho- species in their lower limit of extraction of soil tosyntheticto capacity and conductance of the two moisture we use ritchieritchiesritchiesrRitchieschless 1981 definition of species under water stress imposed naturally in the lower limit of extraction the amount of the field both laboratory and field data support water remaining in the soil when plant growth the hypothesis that in comparison to A deser and activity completely stop I1 toriumcorium L cinereuscicinereousnereus plants deplete soil moisture on the other hand tolerance of very low reserves more completely and maintain higher plant water potentials may offer advantages photosynthetic rates as water supplies are di- other than gaining more water from a particular miniminishedshed but this is achieved through some volume of soil osmotic adjustment may enable sacrifice in water use efficiency by L cinereuscicinereousnereus a plant to maintain turgor in growing roots which in turn would enable the plant to explore METHODS the soil for additional water reserves sharpe and davies 1979 jordan et al 1983 westgate plant materials and boyer 1985 turner 1986 drought toler laymusleymus cinereuscicinereousnereus is a robust tussock grass ant sagebrush antemannemAftemartemisiaaftemisiaisia tritrldentatatmentata plants of native to cold deserts and lower mountain slopes the great basin of north