Great Basin Naturalist Volume 57 Number 1 Article 7 3-7-1997 Ecophysiology of the temperate desert halophytes: Allenrolfea occidentalis and Sarcobatus vermiculatus James D. Trent U.S. Department of Agriculture, Agricultural Research Service, Conservation Biology Rangelands Unit, Reno, Nevada Robert R. Blank U.S. Department of Agriculture, Agricultural Research Service, Conservation Biology Rangelands Unit, Reno, Nevada James A. Young U.S. Department of Agriculture, Agricultural Research Service, Conservation Biology Rangelands Unit, Reno, Nevada Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation Trent, James D.; Blank, Robert R.; and Young, James A. (1997) "Ecophysiology of the temperate desert halophytes: Allenrolfea occidentalis and Sarcobatus vermiculatus," Great Basin Naturalist: Vol. 57 : No. 1 , Article 7. Available at: https://scholarsarchive.byu.edu/gbn/vol57/iss1/7 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 57(1), © 1997, pp. 57--65 ECOPHYSIOLOGY OF THE TEMPERATE DESERT HALOPHYTES: ALLENROLFEA OCCLDENTALIS AND SARCOBATUS VERMICULATUS James D. morl , Robert R. Blank 1,2, and James A. Young l ABSTRACI:-NuOierous basins of the intermountain area often have extensive playa surfaccs that arc nearly (lt~void of vegetation. Margins of these playas support sparse communities dominated by the chcnopod shrubs Allem'Vlfea ncciden­ talis (iodine bush) and Sarcobr;.tu.s veoniculatus (black gt'e.asewuud). These plants estahlish and persist in an environment where halomorphic soils induce extreme osmotic stress and atmospheric precipitation is very low and erratic and occurs largely during the winter when temperatures are too low for growth. We measured net CO2 assimilation rates, leaf con­ ductances, transpiration rates, water-use efficiencies, and stem xylem JXltentials for these two C3 species. Data were col­ lected in above-average (lOOl) and bclow-avemge (1992) precipitation years. Net CO2 assimilation rates for AUenrolfea were statistically simi.lar in 1991 and 1992 but in general declined for Sarcobatus in 1992. For both species, leaf conduc­ tances and leaf lranspin\tion nltes declined signilicantly from 1991 to 1992. with the decline significantly greater for Snr· cobatus. Water-usc efficicncie.<; doubled from 19m to 1992 for hath plant species. Prcdawn xylem waler potentials were -2.2 and -3.3 MPa for Alle7lrol/ea and -1.8 and -2.6 MPa Jor SarcobaLus beginning in May 1991 and 1992, re.<;pectively. and dropped to --3.8 and -4.2 MPa for Allenrolfea and -1.8 and -2.8 MPa for Sarcobatus by September 1991 and 1992, 1"eSpt'.ctively. Afternoon xylem water potentials were --3,1 and -2.0 MPa for Allenrolfea and -2.6 and -2.2 MPa for Sarco­ 1x~ beginning in May 1991 and 1.992, respectively. Xylem water IXltentials dropped to -5.0 MPa for Allewulfca and-3.4 Mfa for Sarcobatus by September of both 1991 and 1992. }obr AIlenmlfea, in general, the total soil water potential within tbtl :r.one of maximum root activity is more negative than the plant's predawn xylem potential, which suAAesls that the plant is partially phr~toplJyticand/or has a large capacitalU.:e due to its extensive woody root syslcm. Key words: iodine bush, hku:k grea.~ewoQd, rhotmynthesis. conductance, transpiratuJt1., water potential, t()(lter~u.sc e!JU;iency, salt desl:f1. lne vast pluvial lakes that occupied the basin Sarcobatus, found in numerous plant commu­ of the intermountain area during the Pleisto­ nities in temperate deserts (e.g., Billings 1945), cene (Russell 1885) exposed extensive lake is moderately salt tolerant and can survive at plains to colonization by plants as the waters the low end of the moisture gradient in salt evaporated during the late Pleistocene. lIalo­ desert communities (Skougard and Brotherson morphic soils, wind erosion, and atmospheric 1979). Sarcobab..., which employs the C3 photo­ aridity hindered colonization of these environ­ synthetic carbon reduction pathway, can be ments (Billings 1945, 1949, West 1983). Lower phreatophytic if the groundwater table is high portions of these basins remain nearly free of enough (Robinson 1958, Rickard 1965, Groen­ vegetation as barren playa surfaces. Margins of eveld 1990). Allenrolfea, also a C3 (scanning tbese playas currently limit plant colonization. electron microscopy ofleafsection did not sbow Communities of shrubs dominated by Cheno­ sbuctures indicative of C4 pathways), is much podiaceae characterize mucb ofthe pluvial lake more restricted in ecological amplitude, being plain environment (Billings 1949). Apparently, limited to a few communities directly at the these shrubs am! half-shrubs bave undergone margin of playas where soils are often poorly explosive evolution in successfully exploiting drained, have high surface soil salinity, but are ti,e lake plain environments (Stutz 1978). The non-sodic (Shantz 1940, Skougard and Broth­ North American endemic chenopods S"rcoba­ ersou 1979). tus vermiculatu. (Hook.) Torr. (black grcase­ The purpose of this study was to determine wood) and the monospecific Allenrolfea occi­ plant strategies that allow Allenrolfea and dentalis (S. Wats) Kuntz (iodine bush) have Sarcobatu.s to sUlVive, indeed flourish, in this colonized extremely saline habitats of these harsh, extremely saline playa margin environ­ temperate desert basins (Young et al. 1995). ment. Our working hypothesis postulated that Ius. Dqurtmcnt"rAgriculture, AgrictJtur.l1 Research s.~. Omsctv:LllolllJi<Jlugy ofIbngc1aJlds Unit. 9'l() \Wley 1\uoId, Reno. NV 89512­ ~g.uU-. 57 58 GREAT BASIN NATURALIST [Volume 57 roots of Sarcobatus tap shallow, lower osmotic plant-water relations and carbon exchange potential groundwater, while roots of Allen­ were measured in above-average and helow­ rolfea primarily seek moisture from the eolian average precipitation years. In the 1st study mounds on which they are found, This hypothe­ diurnal measurements (6--8 measurements from sis was tested by studying plant-soil relation­ sunrise to sunset) of net photosynthesis, leaf ships.and measuring plant ecophysiological conductance, transpiration, relative humidity, attributes for Allenrolfea and Sarcobatus over leaftemperature, and photosynthetically active 2 yr, Fortuitously, the years differed markedly radiation (PAR) were taken with an Ll-6200 in precipitation, which provided insight into portable photosynthesis system (LI-COR, Inc" water acquisition. Lincoln, NE) equipped with a 0.25-L leafcham­ ber. Plots (4 blocks) were randomly selected that METHODS contained both Allenrolfea and Sarcobatus, and ecophysiology measurements were taken The study site is in Eagle Valley, an embay­ by block on 10 July, 2 August, and 25 Septem­ ment of pluvial Lake Lahontan, near the Hot ber 1991 and on 10 July, 8 August, and 23 Sep­ Springs Mountain Range about 80 km north­ tember 1992. To facilitate measurements, stems east of Reno, Nevada (119° 15'W, 39°45'N, containing several leaves were inserted into the 1234 m), Tbe landscape consists ofa lake plain chamber. Mter measurement stems were har­ rising in a series of small (>1 m) escarpments vested and returned on ice to the laboratory bordering a large playa. A band oflarge (>10 where leaf areas were measured. Allenrolfea ill ) sand dunes forms a disjunct arc across the eeophysiologieal measurements were based on lake plain. Allenrolfea forms a very sparse com­ cylindrical leaf area, as stomata appeared to munity, with plants located on low mounds cover the entire leaf Sarcobatus measurements (0.1-0,5 m high) on a former playa surface. were based on a I-sided flat leaf because in Occasional Sarcobatus and/or Atriplex lenti­ formis ssp. tOrt'eyi (Torrey saltbush) share the samples we examined stomata occurred mounds with the smaller Allenrolfea, Discontin­ only on the hairy and flattened leafsurface. uous colonies of Distichlis spicata (desert salt­ In the 2nd study more intensive afternoon grass) are the only herbaceous vegetation found ecophysiology measurements were taken. Mea­ in the communities. Mounds and intermound surements were taken as mentioned above in soils are extremely saline (Tables 1,2) and con­ the diumal study; however, we measured pre­ sist of coarse-textured eolian material overly­ dawn and afternoon stem xylem potentials 'with ing clay- and silt-rich lacustrine sediments a Scholander-type pressure chamber. Measure­ remnant of pluvial periods of Lake Lahontan ments were taken on 30 April, 10 June, 8 July, (Blank et aJ. 1992), The high osmotic potential 30 July, and 23 September 1991 and 20 April, of the soil seedbed limits new plant recruit­ 27 May, 26 June, 16 July, 7 August, and 23 ment (Blank et al, 1994), September 1992, Prior to the studies, 8 perforated PVC In August 1991 we determined rooting tubes were installed throughout the study area depth and root length density for Allenrolfea to monitor the water table, The tubes extended by digging into 4 mounds occupied exclusively to a depth of 3 m. Measurements were taken by Allenrolfea. Roots were collected at depths monthly throughout 1991 and 1992. A sample of 0-30, 30-60, 60-90, 90-120, and 120-150 of the groundwater was returned to the labo­ em, The volume of soil taken was 3780 cm3, ratory and electrical couductivity (EC) deter­ Soil was washed from roots in tubs and organic mined using a salinity drop tester; total water debris was picked from the roots, Root length potential was measured on selected samples was determined using a Comair root length using a Decagon DC-lO thermocouple psy­ scanner (Hawker de Havilland, Salisbury, South chrometer (mention of trade names does not Australia). A subsample of roots were stained imply endorsement by the USDA), with a congo red solution (congo red stains Separate studies were conducted in 1991 dead roots) and examined with a light micro­ and 1992, The 30-yr average annual precipita­ scope to determine the proportion of dead tion for this region is 11.5 em (Reed 1941).