Black-tailed jackrabbit (Lepus cal~ornicus) use of 2 new rangeland seedings in northern and central Nevada was determined by fecal pellet counts for the first growing seasons following seeding establishment. Jackrabbit use was an inverse function of seeding size (as indicated by distance from seeding edges to midpoints). USC was uniformly high for a small (M-ha) seeding from its edge to its midpoint. A larger (4OtSha) seeding received significantly higher use at the edge than at 100-m intervals extending to the 400-m midpoint. Jackrabbit use of seedings was higher during late summer than during early summer. Jackrabbit abundance was significantly higher in sagebrush habitat adjacent to a new seeding than in similar habitat away from the seeding. Our results suggest that forage availability is a factor influencing use of seedings, and predation risk may also be involved.

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AIMhUtDaert sdtgra~~ [DWW sp&utu vu. stdctu (Ton.) Beetle] im the dotit bcrboceous for8ge on many mlb~e r8ngelurdr. Tbe 8bility to direct-seed tbb gr8s~ would permit reveget8ton of dbturbed luline #oils. Seedb~g guidclimr must be b8sed on 8n under-st8ndbq of germbution requirements in relrtion to seedbed conditions. Germbution responaea to 8ltenutbqtemper8turea in r&ion to sodium chloride (NaCl)-reduced osmotic potenti8la were studied in tbe laboratory 8nd ladbed Unity 8nd w8ter potenti8la were merclured ia 8 typial ultgr81111 st8nd in Nevada. Optbnum conditions for raltgr8a germin8tion were 8t -0.1 MP8 osmotic potenti8l8nd 8 200 C differential in cold 8nd w8rm period temper-8turea with w8rm period temper8turen 8bove 300 C. Decrwing oanotic potenti8la from 0 to -2 MP8 decre8sed tbe nte of gcrminrtion from 4.5 to 0.3 and tot81 germbution from 60 to !&across 8ll tempenture @ma. W8ter potenti8ls in tbe lower topogr8pblc81 positiona of 8 typic81 mltgmss st8nd 8fter 8n umcnully wet winter were bigb enough for germbution e-2MP8) in June when temperatures were optimum for genninrtion. In moIt ye8m 8nd on xeric sites, optimum temperature 8nd moisture conditiona would not overl8p to result in bigb germbutton. Some germbution occurs 8t cooler tbln optimum temperatures 8nd low osmotic potenttb. Some aeedn m8y eventtully germbute in mlineaeedbeds under tbeae conditions but bigbest genninltion would be expected when unusu8lly bigb precipit8tion or topogrmphic podtion reaulta in bigb seedbed w8ter poteatbh during l8te spring 8nd wly summer when temperrturea ue optimum. Consequently, irrig8tion during l8te spring 8nd summer sbould produce tbe best stmdda of s8ltgr8ss from direct seeding. Where irrigation b not possible, mltgr8sa sbould be seeded in tbe Id to permit ghtion during euly spring when temper8turea ue suboptbnum but tbe seedbed b still moist. Success of nonirrig8ted seeding~~ will be bigbly dependent on seedbed mlbdty rad moisture conditiona in tbe spring.

The control of greasewood [Sarcobatus vermiculatus(Hook.) Torr.] and salt rabbitbrush [Chrysothamnus nauseosusssp.consimilis(Greene) Hall and Clem.] was investigated with application of 2,4-D [(2,4-dichlorophenoxy)acetic acid] and a mixture of 2,4-D and picloram (4-amino-3,5,6-trichloropicolinic acid). The herbicides were applied at 2-week intervals from May 1 to August 1. Greasewood had accelerated shoot growth and was most susceptible to application of 2,4-D during June. Accelerated shoot growth and maximum susceptibility to 2,4-D of salt rabbitbrush began in June and extended into July. Mortality of greasewood and salt rabbitbrush from 2,4-D at 2.2 kg/ha applied at optimum dates averaged 72 and 87%, respectively. The picloram/2,4-D mixture was more effective for greasewood control than 2,4-D alone in 1 yr at very early and late application dates on a xeric site and only at the last date of application on a mesic site. Reapplication of 2,4-D at 2.2 and 3.3 kg/ha in June to partially controlled stands gave excellent control of both greasewood and rabbitbrush.

Desert saltgrass [Distichlis spicata var. strictu (Torr.) Beetle] is an important forage species of the saline-alkali basins of the western United States. Revegetation of disturbed sites using saltgrass currently involves the use of rhizomes, but seeding saltgrass with conventional equipment would be much more efftcient. The seed and seedbed ecology of desert saltgrass is important to land managers who wish to try new revegetation techniques. The germination of nine collections of saltgrass seed was determined at a wide range of constant and alternating temperatures. The effects of decreasing osmotic potentials on seed germination of one collection was determined using polyethylene glycol and sodium chloride solutions. Seedbed temperatures and moisture potentials were determined during the growing season in two saltgrassstands using thermocouple temperature probes and psychrometers. The temperature regime that produced the highest mean germination (58%) for all nine collections was 10°C for 16 hours alternating with 40°C for 8 hours (10/4oOC). Germination response varied significantly (eO.01) between collections. The best germination was 96% with one collection at the lO/SoOC regime, but most collections germinated best with the lo/400 C regime. For all collections, at least a 20°C diurnal fluctuation in temperature was needed for germination above 10%. Seeds did not germinate at temperatures as cold as-5O C or as hot as 60" C. Saltgrass germination was enhanced at osmotic potentials of-1 bar, but inhibited by potentials lower than-1 bar. No significant (eO.01) germination occurred at-15 bars. Field seedbed temperatures reached optimum levels for germination after moisture potentials were below that required for germination. This suggests that saltgrass seed germination is an episodic event in nature, occurring only when moisture events coincide with optimum seedbed temperatures and can leach sufficient salts to raise moisture potentials above-15 bars. Desert saltgrass [Distichlis spicurn var. stricta (Torr.) Beetle] is an important forage species that can grow vigorously on wet, saline soils where most others will not survive (Nielson 1956). In many of the salt marsh areas of the interior United States, saltgrass provides the sole forage for cattle during the summer portion of the grazing season. Saltgrass is relatively high in protein (Hansen et al. 1976) and highly resistant to excessive grazing. Desert saltgrass is a potential species for revegetating mine spoils and roadsides in the semiarid west (Pavlicek et al. 1977). Large, isolated areas of saltgrass occur in many places throughout the western United States, but seed is produced in very few of these areas. This may be because saltgrass is dioecious and mainly reproduces vegetatively through spreading rhizomes. Saltgrass produces seed only where the stands are most dense and vigorous. Consequently, revegetation using saltgrass has entailed the use of rhizomes (Pavlicek et al. 1977). However, seed sources do exist and The authors are C.J. Cluff, range agro...