Browsing Journal of Range Management, Volume 38, Number 3 (May 1985) by Submit Date
Now showing items 21-24 of 24
Effects of Moisture and Temperature on Germination of Idaho FescueGermination response to varying temperatures and water stress levels during a 30-day incubation period was observed in 4 eastern Oregon collections of Festuca idahoensis Elmer. Seeds were selected from the following habitat types: Artemisia tridentata ssp. wyomingensis/Festuca idahoensis (ARTRV/FEID), Pinus ponderosa Dougl./Festuca idahoensis (PIPO/FEID). One stand of each habitat type was sampled, except for the ARTRV/FEID habitat type where seed was selected from both a high and low elevation plant community. The low elevation stand will be designated ARTRV"L"/FEID. Incubation temperature treatments were held constant (+/- 2 degrees C) and ranged in 5 degrees C increments from 5 degrees C to 35 degrees C. At 15, 20, and 25 degrees C, water stresses of 0.0 MPa, -0.6 MPa, and -0.9 MPa were depressed using polyethylene glycol 6000. Collectively, maximum total germination for all collections occurred at and above 10 degrees C and below 30 degrees C. Germination percentages for seeds from ARTRW/FEID, ARTRV/FEID and PIPO/FEID habitat types at 10 degrees C were 93.0, 97.0, 91.9, and 88.8%, respectively. Maximum germination rates for all collections occurred between 20-25 degrees C. As water stress decreased and temperature increased, both germination amount and rate for the 4 collections declined. Seeds of Idaho fescue collected from sagebrush habitat types maintained higher germination amounts and faster germination rates over wider temperature and moisture stress regime than did seeds selected from the PIPO/FEID site.
Effects of Hunger Satiation on Diet Quality by Grazing SheepThe effect of hunger satiation on selectivity for diet quality by sheep grazing a smooth bromegrass (Bromus inermis) pasture was studied with esophageal fistulated sheep. Fifteen wethers (45.8 +/- .7 kg) were allotted to 5 treatments: nonfasted, fasted for 16 h and then fed 0, 135, 271, or 407 g of pelleted feed. Nonfasted animals were confined at 0800 h and sheep receiving pellets were fed at 0700 h. One animal from each treatment was included in groups released for grazing at 0900, 0930, and 1000 h. Sheep grazed the smooth bromegrass pasture for 30 min. The experiment was conducted on 4 consecutive days. Nonfasted sheep had a lower rate of intake than fasted animals (0 g pelleted feed) (47 vs. 124 mg/min/kg BW^0.75, P<.05), but the quality of the diet selected did not differ (P>.05). All treatment groups selected diets of higher quality than the green fraction of the pasture collected by handclipping. Consumption of increasing quantities of pelleted feed by fasted animals resulted in linear (P<.05) increases in in vitro dry matter disappearance and crude protein content of diet samples. Rate of forage intake and cell wall content of the ingested forage declined linearly (P<.05) with increasing consumption of pelleted feed by previously fasted sheep. Composition of forage cell wall material in the diet samples also changed with pellet feeding, cellulose content increased while lignin content decreased. Overnight fasting of esophageal fistulated sheep did not influence selectivity for forage quality relative to nonfasted animals, but satiation of hunger, as a result of ingestion of a highly digestible feed after a fast, resulted in increased diet quality selected by the animals.
Economic Returns from Burning Tobosagrass in the Texas Rolling PlainsBased on 7 prescribed burning trials on tobosagrass (Hilaria mutica) in the Rolling Plains of Texas from 1968 to 1976, burned tobosagrass ranges yielded an additional present value of $36.16/ha ($14.64/ac) over 5 years with calf prices at $1.62/kg ($.731 lb). Additional costs are $10-12.50/ha ($4-5/ac). These results are based on average precipitation on ranges which had prior chemical treatment on mesquite. The prescribed burns were conducted according to recommended practices.
Automated Rainout Shelter for Controlled Water ResearchAn automated rainout shelter was constructed at the Northern Great Plains Research Laboratory, Mandan, N. Dak., for use in conducting controlled water research to gain a better understanding of soil-plant-water relationships. The design and construction criteria were developed to accommodate many components that were commercially available. The primary components are: (1) foundation, (2) steel I-beam rail, (3) roller mechanism, (4) rainout shelter structure, (5) drive mechanism, (6) electrical control system, and (7) irrigation system. Wind, temperature, and precipitation sensors activate movement of the shelter to cover a plot area 11.5 × 30.3 m (38 × 100 ft), resulting in a modification of the selected environmental conditions. After inactivation of the sensors and a time delay, the rainout shelter automatically returns to its rest position, ready to repeat its cycle when the sensors are reactivated.