Changes in rangeland species composition can effect forage quality, ecosystem function, and biological diversity. Unfortunately, documenting species compositional change is difficult due to a lack of accurate historic records. We took advantage of herbarium records dating from the early 1950's to reconstruct the past flora of a 2,168 ha hardwood rangeland in Mendocino County, California, and then compared this to the current flora of the site. An inventory of vascular plants conducted from 1996 to 2001 added 44 native and 15 non-native species bringing the total number of species and infraspecific taxa at the study site to 671. Of the original 612 species recorded prior to this study, 34 native and 1 non-native species could not be relocated. The percentage of non-native species increased from 19% in 1952 to 23% in 2001. Based on estimates from the early 1950's, mid 1980's, and 1996 to 2001, at least 13 non-native species have increased in abundance, while some native species have decreased. Livestock grazing, competition with invasive species, conversions to different vegetation types, and transportation of propagules into the site by vehicles and livestock, combined with the difficulty of relocating rare species, are posed as the most likely causes for the documented changes.

Rangeland ecological condition was monitored over a 48 year period on 41 sites on Bureau of Land Management rangelands scattered across 6 counties in southwestern New Mexico. All sites were grazed by livestock during the study period. Sampling occurred in 1952, 1962, 1982, 1992, 1997, 1998, and 1999. A modified Parker 3 step method in conjunction with Dyksterhuis quantitative climax procedures were used to determine rangeland ecological condition. At the end of the 48 year study period (1952-1999), the average rangeland ecological condition score across study sites was the same (P > 0.05) as the beginning of the study (39% versus 41% remaining climax vegetation, respectively). Major changes (P > 0.05) in rangeland condition occurred within the study period due to annual fluctuations in precipitation. Ecological condition scores increased in the 1980s and early 1990s due to above average precipitation. However, drought in the early to mid 1950's and again in the mid to late 1990's caused rangeland condition scores to decline. At the end of the study (1997-1999), 38% of the sites were in late seral ecological condition, compared to an average of 25% in the 1952 to 1982 period. The amount of rangeland in late seral ecological condition increased while the amount of rangeland in mid seral and early seral condition decreased in the 1990s compared to the 1952-1962 period. The average percent cover of black grama (Bouteloua eriopoda Torr.) and tobosa (Hilaria mutica Buckley), the primary forage grasses in the Chihuahuan Desert, were the same (P > 0.05) in 1952 and 1999. Over the 48 year study period, the average cover of shrubs including honey mesquite (Prosopis glandulosa Torr.) showed no change (P > 0.05). However major increases in honey mesquite basal cover occurred on 1 site and creosote-bush (Larria tridentata [Pursh] Nutt.) increased on another. Grazing intensity was evaluated during the last 3 years of study (1997, 1998, 1999). Overall grazing use of forage across sites and years averaged 34% or conservative. Our research shows controlled livestock grazing is sustainable on Chihuahuan Desert rangelands receiving from 26-35 cm annual precipitation.

Anecdotal evidence suggests that cattle fed alfalfa hay during the winter are inclined to graze locoweed on spring range. Two studies were conducted to compare the influence of feeding alfalfa hay vs grass hay during the winter on subsequent consumption of white locoweed (Oxytropis sericea Nutt. ex TG) in the spring. Eight cows were daily fed alfalfa hay (15.2% CP in 1998, 17.1% CP in 2000) and 8 cows were daily fed grass hay (10.7% CP in 1998, 12.1% CP in 2000) plus 20% protein molasses block during the January-April winter feeding period. Treatment groups grazed in separate pastures (8 ha) on white locoweed-infested range in May and June in northern Colorado in 1998 and in northeast New Mexico in 2000. Diets were estimated by bite count. There was no difference in locoweed consumption between the 2 groups (P > 0.22). Cattle grazed locoweed for 5% of diets in Colorado and 10% of diets in New Mexico. Feeding alfalfa hay over winter did not predispose cattle to graze locoweed in the spring. Previous research showed other feeding practices or supplements do not affect locoweed consumption or poisoning. Prevention of locoweed poisoning requires denying access to locoweed when it is relatively more palatable than associated forages.

The objectives of this study were to investigate the use of near infrared spectroscopy (NIRS) of fecal samples for predicting the percentage of mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana (Rydb) Beetle) in sheep diets and to quantify the limitations of using NIRS of fecal samples to predict diet composition. Fecal material from a sheep feeding trial with known levels of sagebrush and several background forages was used to develop fecal NIRS calibration equations validated with fecal material from 2 other sheep feeding trials with known levels of sagebrush in the diets. The 1996 calibration trial varied the level of sagebrush, alfalfa, and grass hay in the diets. The 1998 trial compared frozen to air-dried sagebrush. The Wyoming trial was a metabolism study using frozen sagebrush. Trials used different levels of sagebrush varying from 0 to 30% of the diet in increments of 4 to 10 percentage points. Internal validation of the 1996 trial with a subset of the samples not used for calibration showed that when predicted samples are from the same population as the calibration samples, this procedure can accurately predict percent sagebrush (R2 = 0.96, SEP = 1.6). However, when predicted samples were from a different population than calibration samples, accuracy was much less, but precision was not affected greatly. Low accuracy was caused by a compression of the range of data in the predicted values compared to the reference values, and the predicted sagebrush levels in the diet should be considered to represent an interval scale of measurement. Modified partial least squares regression resulted in better calibration than stepwise regression, and calibration data sets with only high, low, and no sagebrush resulted in calibrations almost as good as data sets with several intermediate levels of sagebrush. High values of the H statistic were related to low precision but did not affect the accuracy of predictions. We believe the interval scale of measurement will contain sufficient information for the purpose of addressing many questions on rangelands.

The Walker Basin Allotment grazing system in central Arizona is designed to allocate resource use under elk (Cervus elaphus L.) and cattle (Bos taurus L.) grazing. The grazing system was designed to promote biologically acceptable levels of forage use on the half of the allotment scheduled for cattle grazing and to rest the other half by attracting elk to pastures recently grazed by cattle. The objectives of our 2-year study were to determine whether the grazing system facilitated proper forage use as defined by recent forage use and residual stubble height guidelines (i.e., 30 to 40% use and an 8- to 10-cm stubble height) and whether the system rested one half of the allotment from elk and cattle grazing. Mean (+/- SEM) total elk and cattle forage use for western wheatgrass (Pascopyrum smithii Rydb.), the key forage species, was 32 and 61% +/- 7 in 1997 and 1998, respectively; corresponding mean (+/- SEM) stubble heights were 11 and 10 cm +/- 0.6. Mean total cattle and elk forage use in 1998 (61%) exceeded the 30 to 40% use guidelines. However, mean end-of-year stubble height was never below 10 cm. The grazing system did not provide half the allotment with complete rest; elk used all study pastures. Elk use was higher in pastures with heavier tree cover and steeper terrain in both years, regardless of where cattle grazing occurred. Elk grazing patterns were apparently more dependent on tree cover and topography than any changes in forage caused by the grazing system.

Both large ungulates and wildlife tourists tend to concentrate along the Chobe River in Chobe National Park, Botswana, during the dry season causing concern for wildlife habitat and the recreational experience for wildlife viewers. Therefore, ground reconnaissance inventory data of 5 most common large ungulates were collected during the early morning and late afternoon hours along tourist routes in 5 different habitat types every second month for a period of 24 months in Chobe National Park to determine their relative, seasonal habitat preference and availability for viewing by vehicular tourists. A total of 909 herds: greater kudu (Tragelaphus strepsiceros), 285; impala (Aepyceros melampus), 209; elephant (Loxodonta africana), 200; giraffe (Giraffa camelopardalis), 138; and buffalo (Syncerus caffra), 77 were observed during the 760 observation periods. The average frequency of observation of a herd of 1 or more of these 5 ungulates per habitat type was alkali flats, 3.42; floodplain grassland, 2.67; shrub savanna, 2.29; tree savanna, 1.04; and woodland, 0.30. This order of frequency of observation is highly correlated with nearness to the Chobe River, the major water source during the dry season. Elephant and giraffe were more wide-ranging than buffalo, impala, and kudu. During the dry season, all animals were seen more often on the floodplain grassland in the afternoon than in the morning. Giraffe were never seen in any habitat type in December, and impala were never seen in the woodland in any month. Our data confirm that tour operators interested primarily in providing their guests with a view of the greatest numbers of animals in a limited period of time are justified in congregating along the Chobe River during the dry season. However, as in most public wildlife reserves, Chobe National Park management is faced with the decision of how best to optimize the biological needs of Park animals and their habitat with the economic and recreational desires of Park users.

Early weaning of calves can improve reproduction of beef cows, and would be of no detriment to calf growth if the diet is adequate. Digestible energy intake could be limiting, however, when calves are weaned on forage. Performance of calves weaned at 70 days (early weaning) and 172 days (normally weaning) of age were compared. Calves from 2 locations in Argentina, Anguil, and Chacharramendi, were distributed in 14 groups and half were weaned. Early-weaned calves were pen fed a 50% concentrate-50% alfalfa hay diet for 12 days, followed by grazing on alfalfa for 150 days. During the first 90 days on pasture, early-weaned calves were group supplemented (1.2 % body weight (BW, DM basis). Calves from Anguil did not differ (P = 0.068) in average daily gain (ADG). In contrast, early-weaned calves from Chacharramendi gained faster than normally-weaned calves (P 0.01). In a second experiment, 108 calves were classified into 3 age groups on day 0 of trial (AGE1 = 109 +/- 2.2 days of age, AGE2 = 91 +/- 1.6 days of age and AGE3 = 75 +/- 3.8 days of age). Two thirds of the calves were weaned (early-weaned calves) the same day and the remaining third was returned to their dams (normally-weaned calves). Two feeding treatments were imposed on the early-weaned calves: S15 = supplement during the first 15 days on pasture (1% body weight, DM basis), and S45 = supplement during the first 45 days. Early-weaned calves grazed on an alfalfa pasture for 136 days. Calves from the normally-weaned group remained with their mothers until weaning onto pasture on day 87 of the study. Normally-weaned calves were the heaviest (P < 0.05) at the end of trial. Differences in body weight between early weaning ages increased as the supplementation period decreased. Calves that were weaned at 75 days of age and fed supplement for only 15 days had the lowest (P < 0.05) overall ADG and final body weight. Overall results suggested that early weaning favors reproduction of thin cows, and early-weaned calves can be placed on good-quality pasture with no detriment of growth if energy supplement is provided.