Germination Requirements of Key Southwestern Woody Riparian Species

Item Type Article

Authors Siegel, Richard S.; Brock, John H.

Publisher University of Arizona (Tucson, AZ)

Journal Desert Plants

Download date 29/09/2021 04:10:45

Link to Item http://hdl.handle.net/10150/609112 Siegel and Brock Germination Requirements 3

Introduction Germination Riparian habitats in the Southwestern United States are known not only for their diversity in both plant and animal life but also for the water that these areas provide. However Requirements of Key in recent years, riparian habitats have been degraded, or de- stroyed by flooding, channelization, phreatophyte control, Southwestern Woody agricultural practices, overgrazing, recreation, and off -road vehicle abuse. (Davis, 1977; Carothers, 1977). Flooding has Riparian Species been responsible for the destruction of many mature riparian forest stands in the Southwest, but flooding is also necessary for the establishment of many stands (Brady et al., 1985). Riparian forests play a major role in the mainte- S. nance of this unique ecosystem which provides shade and Richard Siegel cover for wildlife during hot summer months, and sanctu- Department of Water Resources, State of Arizona ary for numerous species of birds. Therefore, it is important that the damage to riparian zone be mitigated by the estab- and John H. Brock lishment or riparian vegetation. Revegetation research of Southwestern riparian habitats of Agribusiness and Environmental Resources, School within the past ten years has been centered on the woody Arizona State University, Tempe species of the ecosystem. Anderson et al., (1978), York (1985) and Swenson and Mullins (1985) have reported on revegetation techniques using poles or dormant stubs as vegetative propagules. Pope and Brock (1988) report on the potential of the propagation technique of hardwood stem cuttings to provide large numbers of transplants for use in riparian habitat reformation. Several authors (Brock, 1984; Brady et al., 1985; Larkin, 1987) have observed seedling establishment of riparian species in nature. The use of seeds for revegetating riparian habitats has not been reported probably because of two reasons; (1) lack of readily available seed sources and (2) lack of knowledge of environmental factors regulating germination of woody riparian species. Horton et al., (1960) described general germination responses of selected phreatophyte species, Fenner et al., (1984) reported on germination of Fremont cottonwood as influenced by moisture stress, and Stromberg- Wilkens and Patten (1985) have included germination observations in their report of greenhouse and field studies of Arizona walnut. The overall objective or this research was to develop information for the revegetation of degraded riparian zones by studying the environmental conditions required for the Abstract germination of selected riparian tree species. The specific Germination requirements of selected Southwestern objective was to investigate important germination condi- woody riparian species were studied in the laboratory. Four tions of four major Southwestern woody riparian species: common tree species selected for study were Fremont Cot- Fremont Cottonwood (Populus fremontii), Goodding Willow tonwood (Populus fremontii), Goodding Willow (Salix (Salix gooddingii), Arizona Sycamore (Platanus wrightii) gooddingii), Arizona Sycamore (Platanus wrightii) and Vel- and Velvet Mesquite (Prosopis velutina). vet Mesquite (Prosopis velutina). Seeds were collected from two major riparian habitats in the southwest. The Methods and Procedures species tested required a temperature range of 16° C to 27° Seeds for this study were collected from two major ripar- C for germination. Fremont Cottonwood, Goodding Wil- ian areas of the Southwest. One area was neár the Gila low and Velvet Mesquite showed good germination at River, located approximately 78 km northwest of Silver moisture stress levels of -4 bars or less, whereas Arizona City, New Mexico. The second area was on the San Fran- Sycamore only germinated well at 0 bars. For all species cisco River approximately 30 km north by northeast of tested, germination was better at salinity levels lower than Clifton in eastern Arizona. Seeds were collected in the 50 meq /liter NaCl. All species displayed successful germi- years of 1982 and 1983. Seeds from the Fremont cotton- nation responses between pH 5 to 7. Velvet Mesquite ger- wood trees were harvested in early May and from the minated at all pH levels (5 -10). Longevity of seeds of ripar- Goodding willow trees in late May and early June. Velvet ian species is reported to be of short duration. This was mesquite seeds were collected in August of each year. confirmed in these studies with southwestern woody ripar- Seeds of Arizona sycamore were collected in January of ian species. 1983 and 1984. All seeds were harvested during periods of 4 Desert Plants 10(1) 1990

VELVET were phosphate buffered to reduce toxicity effects (Cooper, MESQUITE 1977). (NaC1) so- a a a a Sodium chloride was used to prepare salinity 100 ------lutions used as germination media. Six salt levels of 0, 25, e 50, 100, 200, and 300 meq were utilized. The upper limits 90 b'. of salinity are at levels where only a few very tolerant plants will yield satisfactorily (Richards 1969). 80 g GOODDING FREMONT Water stress was simulated using polyethylene glycol WILLOW 70 COTTONWOOD (PEG) 20,000 (atomic weight of the molecules) in the irriga- 60 tion water. Solutions of PEG with levels of -2, -4, -8, 12, r w ARIZONA -- -d. SYCAMORE and -16 bars of water potential were prepared following 50 . x procedures described by Thill et al., (1979). Distilled water X ` s 40 - . o, served as the 0 bar treatment. t' Longevity of seeds was determined by germinating seeds 30 over regular time intervals (weeks) following seed collec- 20 tion. Viability was confirmed by germination and tests . ceased when germination percentages were zero, or nearly IO . so, for two time intervals. z Seeds were considered germinated when the radicle had IO 16 2I 27 33 38 emerged more than 2 mm from the seed coat for velvet mesquite and Arizona sycamore. For Fremont cottonwood TEMPERATURE °C and Goodding willow, the seeds were considered germi- Figure 1. Average percent germination of seeds of selected nated when the cotyledons broke free of the seed coat or a woody riparian species as influenced by temperatures. ring of root hairs began fringing the hypocotyl. Germina- Means with the same letter are not significantly different tion data were transformed to arc -sine angles prior to at the P = 0.05 level using the Student -Newman -Kuel's analysis. Analysis of variance procedures in SAS (1982) test. were used to detect the differences among treatments. Where significant differences among treatments were indi- cated by F tests, the means were separated using the Student -Newman -Keuel's test (Steel and Torrie 1960). All natural dispersal. Because of the short period of viability of analyses and tests utilized a probability level of 0.05. Data Fremont Cottonwood seeds (Fenner et al., 1984) and reports from the two germination tests for each species were found of similar viability for willow, Goodding seeds of each to be similar, and were pooled in final statistical analyses. species was tested immediately after harvest. A sample of Regression analyses were performed on the response data all seeds lots were for viability using the tetrazolium treated to provide a measure of variability. These analyses in- technique (Grabe 1970). After viability was confirmed, cluded best fit equations of linear or quadratic formed to the remaining seeds were then subjected to experiments the observed data. Regression analysis using exponential to determine germination success as influenced by tern - (cubic) or logarithmic transformations did not appreciably perature, water stress, pH and salinity of the surrounding account for more variation compared to simpler relation- environment. All germination tests were placed into a ships. completely randomized design with four replicates per treatment. Each replicate of Goodding Willow and Fre- mont Cottonwood -consisted of fifty seeds. Replicates of Results and Discussion Velvet Mesquite and Arizona Sycamore contained twenty - Germination Response to Temperature. Arizona Syca- five seeds. The seeds were placed in a disposable 9 cm petri more and Goodding Willow both had significantly better dish on two number 1 qualitative filter papers. Each dish germination response at 27° C (92% and 55% respectively) was then irrigated with 5 ml of germination solution and (Fig. 1). The best germination response for Fremont Cot- placed on a thermogradient table (Copeland, 1976) or in an tonwood seeds was between 16° C and 21° C, and was sig- incubator. Data on germination rates and total germina- nificantly greater than other temperature levels. Velvet tion was recorded daily for 14 days following test initia- Mesquite showed excellent germination at all temperature tion. Each germination test was conducted 2 times. levels, especially at those above 16° C, a pattern also ob- The seeds for each species were germinated on a thermo- served in studies with honey mesquite (Prosopis gladulosa) gradient table, with temperatures ranging from 10° C to 38° in Texas (Scifres and Brock, 1969). These optimal germina- C. Specific temperatures used were 10° C, 16° C, 21° C, 27° tion temperatures were used in the other experiments on C, 33° C and 38° C. From this experiment the optimum ger- water stress, salinity and pH. For uniformity in procedures, mination temperature was established for the four tree velvet mesquite seeds were placed at 27° C for further test- species. The pH, water stress and salinity germination ing. tests were conducted at the optimum temperature for each Regression techniques were used to assess variability in species. the observed data to the environmental factor studied. Seven acid or alkaline solutions of germination media Eighty -one percent of the experimental variation observed were prepared using sulfuric acid or sodium hydroxide to for velvet mesquite germination response to varied tern - produce pH levels of 4, 5, 6, 7, 8, 9, and 10. The solutions peratures was explained by a regression equation of quad- Siegel and Brock Germination Requirements 5 lok

C Figure 2. Goodding Willow germination response to temperature treatments after 72 hours. Photo A is 10°C with cotyledons expanding. Photo B is 16 °C with root hairs visi- ble on the hypocotyl margins. Photo C is 21 C° with dense roothairs and the initial development of the primary root. Photo D is the optimal, 27 °C, showing primary root development at 72 hours. By 96 hours at 33 °C, the seedlings were flaccid and did not persist. ratic from (Table 1). A quadratic equation for Goodding observed for seedlings of Velvet Mesquite at 38° C. The re- Willow, provided for 96% (from the coefficient of determi- sponse to temperature ranges as illustrated for Goodding nation (R squared) value) of the variation in the data. Willow was also observed for Fremont Cottonwood and Regression analysis of Fremont Cottonwood and Arizona Arizona Sycamore. Germination occurred at higher tem- Sycamore germination response data to temperature levels peratures, but by the end of the 7 day observation period showed that 85% and 71% respectively, of the variation seedlings in the 38° C treatments were dead. was explained with quadratic equations. Simulated Water Stress. Simulated water stress using The effect temperature has on germination of riparian PEG 20,000 had very apparent effects on germination re- species can be illustrated by photographs of Goodding Wil- sponse among seeds of the four riparian tree species low seeds taken during germination process (Fig. 2). While studied. At -2 bars, the average percent germination of all treatments resulted in seed germination, there were Arizona Sycamore decreased, significantly, by more than readily apparent seedling responses to various tempera- 50 %, with a similar significant loss observed at the -4 bars tures after 72 hours of exposure. At lower temperatures level (Fig. 3). Velvet Mesquite showed a similar response (Fig. 2, A and B), the cotyledons had expanded and root pattern with seeds at less water stress having significantly hairs were present at the base of the hypocotyl. Growth of better germination success. Seeds of Honey Mesquite the primary root was observed after 72 hours in replicates responded similarly to water stress levels induced by man - where temperatures were 21° C or higher (Fig. 2, C, D). nitol solutions (Scifres and Brock 1969). Germination of After 96 hours, the Goodding Willow seedlings in the 33° C Fremont Cottonwood decreased by almost 100% (Fig. 3) treatment had experienced thermal death. This was also among seeds at the -8 bars level, a pattern also observed by 6 Desert Plants 10(1) 1990

riparian a Table 1. Regression analysis for response of woody 100 tree species to germination tests including temperature, é e simulated water stress, salinity and pH levels. 90 Test /Species Response Form R2 S.E. 80 Temperature GOODD ING Velvet Mesquite Quadratic 0.81 3.05 Goodding Willow Quadratic 0.96 7.03 70 WILLOW Fremont Cottonwood Quadratic 0.85 7.05 Arizona Sycamore Quadratic 0.71 12.64 Water stress 60 Velvet Mesquite Linear 0.85 14.20 Goodding Willow Linear 0.83 17.28 VELVET Fremont Cottonwood Linear 0.73 8.89 50 MESQUITE Arizona Sycamore Quadratic 0.82 8.85 Salinity 40 Velvet Mesquite Quadratic 0.57 12.09 FREMONT Goodding Willow Linear 0.91 11.53 r Fremont Cottonwood Quadratic 0.68 9.14 30 .6 COTTONWOOD Arizona Sycamore Linear 0.83 7.03 pH b b Velvet Mesquite Linear 0.02 6.98 20 Goodding Willow Quadratic 0.43 26.87 Fremont Cottonwood Linear 0.09 10.98 IZONA ` ., b Arizona Sycamore Linear 0.42 6.20 10 gh SYCAMOR ~ h z Table 2. Optimal germination responses for seeds of selected O -2 -4 -6 -8 -IO -12 -14 -16 Southwest woody riparian species. WATER POTENTIAL ( bars ) Species Optimal Germination Response Figure 3. Average percent germination of seeds of selected Velvet Mesquite 10° through 38° C 0 to -4 bars water stress Southwestern riparian species as influenced by simulated 0 to > 100 meq /1 salinity water stress in the germination media. Means with the pH 4 through 10 Goodding Willow 21° C to 27° C temperatures same letter are not significantly different at the P = 0.05 0 to -2 bars water stress level using Student -Newman -Kuel's test. 0 to > 100 meq /1 salinity pH 6 to 7 Fremont Cottonwood 16° to 21° C temperatures 0 to -4 bars water stress for Gooding Willow and Arizona Sycamore, there were sig- 0 to >50 meq /1 salinity nificant reductions in germination success at the 50 meq /1 pH 5 to 7 Arizona Sycamore 27° C temperatures concentration. The germination response of velvet mes- 0 water stress quite showed no significant difference among the salinity 0 salinity pH 5 to 7 treatment levels, although average germination was lower at the 200 and 300 meq /l levels (Fig. 4). High salt levels influenced the apparent vigor of the seedlings, especially Fenner et al., (1984) using mannitol solutions. Goodding those of Fremont Cottonwood, Goodding Willow and Ari- Willow showed a response similar to Fremont Cotton- zona Sycamore. The germinated seedlings were a chlorotic wood, with significantly lower germination success as green and the root apices were commonly necrotic. When osmotic potentials increased. rinsed and transferred to deionized water after conclusion Variation in average seed germination response to simu- of the tests, these seedlings did not display normal growth, lated water stress levels for Velvet Mesquite, Goodding however, some did survive. Willow and Fremont Cottonwood were explained by linear Velvet Mesquite and Fremont Cottonwood seed germi- relationships (Table 1). The variation in average seed ger- nation response data to salinity levels provided wide varia- mination response to simulated water stress levels for Velvet tion in the replicates. This is reflected in the coeffecient of Mesquite, Goodding Willow and Fremont Cottonwood were determination values (R- squared) of 0.57 for velvet mesquite explained by linear relationships. The variation explained and 0.68 for Fremont Cottonwood (Table 1). In both cases in the germination response to water stress for these the best fit equation was of the quadratic form. Goodding species was 85% for velvet mesquite, 83% for Goodding Willow and Arizona Sycamore regression analyses to the Willow and 73% for Fremont Cottonwood. Arizona Syca- observed germination responses of varying salinity levels more germination response to water stress provided a were linear. These regression analyses provided R- squared quadratic equation which accounted for 82% of the varia- values of 0.91 and 0.83 for Goodding Willow and Arizona tion observed in the data set. Sycamore respectively. Variation in the experiments not At the end of the study periods, seedlings or seeds, were accounted for by the salinity treatments for these 2 species rinsed with deionized water and transferred to deionized was 9 and 17 percent. water media. Germinated seedlings or seeds subjected to pH Levels. More variation in the response of seeds to pH water stress conditions (> -8 bars) exhibited what ap- treatments was observed than for the other environmental peared to be normal growth once the water stress condition factors in this paper. However, examination of the central was removed. tendency of the data does allow some observations to be Salinity. Goodding Willow, Fremont Cottonwood, and made. The effect of pH on average germination response of Arizona Sycamore had the best germination response in the four species showed that Velvet Mesquite had the saline solutions between 0 and 50 meq /1 NaCl. Although, widest range of tolerance. There was no significant differ- Siegel and Brock Germination Requirements 7

a ai- VELVET 100 i-- a MESQUITE 90 . VELVET a a a MESQUITE 100 a a 80 --- ,_ . . .` a 90 e . a . 70 GOODDING a 80 WILLOW --.., GOODDING 60 70 WILLOW g 50 60 FREMONT 40 r 50 ARIZONA x COTTOWOOD SYCAMORE 30 40 `\s. WX 30 rs wx xy 20 g fs----o--- b rs, yz ARIZONA 20 i IO SYCAMORE t h FREMONT rs IO - COTTONWOOD g z O 25 50 I00 200 300 4 5 6 7 8 9 IO

SALT (NaCI; meq /I) P H Figure 4. Average percent germination of seeds of selected Figure 5. Average percent germination of seeds of selected Southwestern riparian species as influenced by salinity of Southwestern woody riparian species as influenced by pH the germination solution. Means with the same letter are of the germination media. Means with the same letter are not significantly different at the P = 0.05 level using not significantly different at the P = 0.05 level using Student -Newman -Kuel's test. Student -Newman -Kuel's test. ences among the pH levels for Velvet Mesquite seed germi- LONGEVITY OF GOODDING WILLOW SEEDS nation (Fig. 5). Fremont Cottonwood and Arizona Syca- 100 - more had a narrower range of germination response to pH, although germination percentages were not as high as in 90 the temperature tests. Mean germination success of Fre- 80 mont Cottonwood and Arizona Sycamore was significantly lower in alkaline pH solutions. Goodding Willow 70 had the narrowest response range, with better germination 60 occurring in pH 6 or 7 solutions (Fig. 5). Best germination for Fremont Cottonwood, Goodding Willow, and Arizona 50 Sycamore was between pH 5 and 7. At more acid or alka- 40 line pH levels, seedlings germinated but the color of the cotyledons became either chlorotic (acid) or a drab olive 30 green (alkaline), indicating unfavorable conditions. Devel- opment of seedlings of these riparian species was best near 20 levels. neutral or slightly acid pH 10 Wide variation in the response data for pH is reflected in the coeffecient of determination calculated in regression O I l I I O I 2 3 4 5 6 7 8 9 10 II 12 analyses. The data points were widely scattered and as a result, the R- squared values associated with pH levels were WEEKS all below 0.50, with Velvet Mesquite having the lowest Figure 6. Longevity of Goodding Willow seeds as evi- value (Table 1). denced by germination success. Seeds were collected in Optimal Germination Regimes. Environmental condi- late May 1982. Seeds were stored in the laboratory at tions favoring successful germination of the four South- approximately 24 °C in air -tight containers. western woody riparian species tested in the studies reported in this paper are summarized in Table 2. Velvet mesquite 1960) and seeds of the Mesquite genus have been reported had the widest germination response to the varying tem- to retain viability for years (Simpson, 1977). For this reason, peratures, water stress, salinity and pH levels. In contrast, longevity of Velvet Mesquite seed viability was not at- Arizona Sycamore had narrow successful responses. Fre- tempted in this study. Mesquite seed longevity is attributed mont Cottonwood and Goodding Willow had germination to its having a hard seed coat. On the other hand, Fremont responses that were intermediate to Velvet Mesquite and Cottonwood has been reported to have fairly brief seed via- Arizona Sycamore. Research with these two members of bility for seeds under field and greenhouse conditions (Horton the Salicaceae family supports results reported by Horton et al., 1984). Germination to Fremont Cottonwood was re- et al., (1960) and Fenner et al ., (1984). ported by Fenner et al., (1984) to be approximately 20 weeks for laboratory stored seeds. Because longevity of Longevity of Seeds viability in Fremont Cottonwood has been established, we In general, Velvet Mesquite seeds (Tschirley and Martin, did not include this species in our seed longevity studies. 8 Desert Plants 10(1) 1990

in restoration and management of riparian habitats can be 60 LONGEVITY OF ARIZONA SYCAMORE SEEDS enhanced.

Acknowledgments 50 This research was conducted with funding supplied by the Bureau of Reclamation. During the study period, John H. Brock carried an Interagency Personnel Agreement with the U.S. Forest 40 Service, Rocky Mountain Forest and Range Experiment Station, Arizona State University, Tempe, Arizona.

30 Literature Cited Anderson, B. W., R. D. Ohmart and J. Disano. 1978. Revegetating 20 the riparian floodplain for wildlife. In: Strategies for Protection and Management of Floodplain Wetlands and Other Riparian Ecosystems. USDA, Forest Service, GTR- WO -12. p. 318 -331. Brady, W., D. R. Patton and J. Paxson, 1985. The development of 10 riparian gallery forests. In: Riparian Ecosystems and Their Man- agement: Reconciling Conflicting Uses. First North American Riparian Conference. USDA, Forest Service, Rocky Mtn. Forest

, I I o i and Range Esp. Sta. GTR -RM -120. p. 39 -43. 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Bock, J. H. and C. E. Bock, 1985. Patterns of reproduction in WEEKS Wright's sycamore. In: Riparian Ecosystems and Their Manage- Figure 7. Longevity of Arizona Sycamore seeds as evi- ment: Reconciling Conflicting Uses. First North American denced by germination success. Seeds were collected in Riparian Conference. USDA, Forest Service, Rocky Mtn. Forest and Range Exp. Sta. GTR -RM -120. p. 493 -494. February 1983. Seeds were stored in the laboratory at Brock, J. H. 1984. Some Autecological Studies on Regeneration °C -tight containers. approximately 24 in air and Maintenance of Selected Riparian Plant Species. Final Re- port to U.S. Bureau of Reclamation. 166 p. Carothers, S. W. 1977. Importance, perservation, and management Reports on longevity of Goodding Willow and Arizona of riparian habitats: an overview. In: Importance, Preservation Sycamore seeds were not found in the literature. From our and Management of Riparian Habitats: A Symposium. USDA tests, the longevity of Goodding Willow seeds, stored Forest Service Gen. Tech. Report RM -43. p. 2 -4. under laboratory conditions, was found to be approxi- Cooper, T C. 1977. The Tools of Biochemistry. John Wiley and mately 10 weeks (Fig. 6). Good germination (> 50 %) was Sons Publishing, New York, NY 423 p. observed until seeds reached about 6 weeks from time of Copeland, L. O. 1976. Principles of Seed Science and Technology. dispersal. Percentage germination decreased rapidly after Burgess Publishing Co. Minneapolis, MN. 369 p. Davis, G. K. 1977. Management alternatives for riparian habitats that time and after 10 weeks, seed germination was near in the southwest. In: Importance, Preservation, and Manage- zero. After 12 weeks no seeds of Goodding Willow germi- ment of Riparian Habitats: A Symposium. USDA Forest Ser- nated. vice Gen. Tech. Report RM -43. p. 59 -67. Arizona Sycamore seeds showed greater longevity than Fenner, P. R., W. W. Brady, and D. R. Patton. 1984. Observations Goodding Willow, although the general trend was a reduc- on seeds and seedlings of Fremont cottonwood. Desert Plants tion of about 5% germination for each 2 weeks of addi- 6:55 -58. tional seed age (Fig. 7). Germination of Arizona Sycamore Grabe, D. F. 1970. Tetrazolium Testing Handbook for Agricultural approached zero when laboratory stores seeds had been in Seeds. Association of Official Seed Analysts. collection about one -half of a year (26 weeks). Horton, J. S., F. C. Mounts, and J. M. Kraft. 1960. Seed Germina- tion Seedling Brief longevity (weeks), appears to be a common charac- and Establishment for Phreatophyte Species. USDA Forest Service, Rocky Mtn. For, and Range Esp. Sta. teristic among seeds of many riparian species. This charac- Research Paper No. 48.26 p. teristic plus the sporadic soil -water relationships found in Larkin, G. J. 1987. Factors Influencing Distribution and Regenera- the Southwest adds to the limited success of seed regeneration of Riparian Species along Mountain Streams in Central tion by woody species in riparian habitats. However, when Arizona. Unpublished M.S. Thesis. Department of Botany and there is a juxtaposition of favorable environmental condi- Microbiology. Arizona State University. Tempe, AZ. 84 p. tions and seed dispersal, very dense stands of seedlings of Pope, D. P., J. H. Brock and Ralph A. Backhaus. 1990. Vegetative riparian species have been observed by many field personnel. propagation of key southwestern woody riparian species. Desert Plants 10(2:91 -95. Richards, L. A. ed. 1969. Diagnosis and Improvement of Saline and Conclusions Alakali Soils. USDA, Ag. Res. Serv., Ag. Handbook 60. 160 p. SAS Institute. 1982. SAS User's Guide: Statistics. SAS Institute, The environmental parameters examined in this paper Inc. Gary, NC 584 p. describe some of the important requirements influencing Scifres, C. J. and J. H. Brock. 1969. Moisture -temperature interrela- germination of key Southwestern woody riparian species. tions in germination and early seedling development of mes- When dealing with seed germination many factors need quite. J. of Range Manage. 24: 334 -337. evaluation. With better knowledge of the environmental factors influencing seed germination and early seedling Continued growth coupled with seed longevity information, success on page 34 34 Desert Plants 10(1) 1990 laboratory mill. The percentage of ether extract (lipid) was U.S. Dept. Agric. Handbook No. 379.20 pp. determined by the procedure described by the Association Horejsi, R. G. 1982. Mule Deer Fawn Survival on Cattle -Grazed and of Offical Agricultural Chemists (1980). Fiber, lignin, and Ungrazed Desert Ranges. Arizona Game and Fish Dept., Fed cellulose were determined according to Goering and Van Aid Fish and Wildl. Restor. 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Results of chemical analyses are presented in Table 1. A Natl. Climatic Cent. Asheville, N. C. 29 pp. knowledge of nutritional values of key forage species has Payton, T. W., and G. W. Garner. 1980. Nutritional values for practical application in ungulate management and re- selected forages of desert mule deer in southwest Texas. Proc. search. Our purpose was to present the nutritional quality Ann. Cont. West. Assoc. Fish and Wildl. Agencies 60: 601 -619. of key forage plants as an easily accessed reference. Forage Rautenstrauch, K. R., P. R. Krausman, Frank M. Whiting, and W. quality can be used as a criterion for assessing the quality H. Brown. 1988. Nutritional quality of Desert Mule Deer forage in King Valley, Arizona. Desert Plants 8: 172 -174. of habitats. Monitoring seasonal nutritional levels of key Reynolds, H. G. 1967. Chemical constituents and deer use of some forage species can help wildlife managers determine when crown sprouts in Arizona chaparral. J. Forest. 65: 905 -908. the habitat is most productive and may provide clues as to Sellers, W. D., and R. H. Hill. 1974. (eds.) Arizona Climate: 1931- when and if diet supplements are called for. This is espe- 1972. Univ. Ariz. Press. Tucson. 616 pp. cially important on ranges shared by native ungulates and Short, H. L. 1977. Food habits of mule deer in a semidesert grass - livestock. shrub habitat. J. Range Manage. 30: 206-209. Swank, W. G. 1956. Protein and phosphorous content of browse Literature Cited plants as an influence on southwestern deer herd levels. Trans. Association of Official Agricultural Chemists. 1980. Official North Amer. Wildl. Conf. 21: 141 -158. Methods of Analysis. 12th ed. Association of Official Agricul- Urness, P. J., W. Green, and R. K. Watkins. 1971. Nutrient intake of tural Chemists. Washington. D.C. 1015 pp. deer in Arizona chaparral and desert habitats. J. Wildl. Manage. Goering, C. G., and P. J. Van Soest. 1970. Forage Fiber Analyses. 35: 469-475.

Swenson, E. and C. L. Mullins. 1985. Revegetating riparian trees in Germination Requirements Southwestern floodplains. In: Riparian Ecosystems and Their - Continued from page 8 Management: Reconciling Conflicting Uses. First North American Riparian Conference. USDA, Forest Service, Rocky Mtn. Forest and Range Exp. Sta. GTR -RM -120. p. 135-138. Thill, D. C., R. D. Schriman, and A. P. Appleby. 1979. Osmotic sta- Simpson, B. B. ed. 1977. Mesquite: Its Biology in Two Desert Scrub bility of mannitol and polyethylene glycol 20,000 solutions Ecosystems. Dowden, Hutchinson and Ross, Inc. Stroudsburg, used as seed germination media. Agron. J. 71:105 -108. PA 250 p. Tschirley, F. H. and S. C. Martin. 1960. Germination and longevity Steel, R. G. D. and J. H. Torrie. 1960. Principles and Procedures of of velvet mesquite in the soil. J. of Range Manage. 13: 94 -97. Statistics. McGraw -Hill Book Co., Inc., New York, NY 481 p. York, J. C. 1985. Dormant stub planting technique. In: Riparian Stromberg- Wilkens, J. and D. T. Patten. 1985. Silvics of Arizona Ecosystems and Their Management: Reconciling Conflicting Walnut. Final Report to Rocky Mtn. Forest and Range Exp. Sta. Uses, First North American Riparian Conference. USDA, Forest Arizona State University, Center for Environmental Resources, Service, Rocky Mtn. Forest and Range Exp. Sta. GTR -RM -120. Tempe, AZ. 62 p. p. 513 -514.