Because most of Texas consists of privately owned land and the amount of brush cover on rangelands may affect off-site water yields, there has been increasing interest in publicly funded brush clearing programs aimed at increasing water yield. The Pedernales River was selected as 1 of 8 watersheds to determine the feasibility of implementing such a program. A survey questionnaire was mailed to 720 landowners in Blanco and Gillespie County (containing most of the Pedernales watershed) in June 2000 to identify factors that influence their interest in participating in a brush reduction program. The sample consisted of equal numbers of landowners with 4–20, 21–202, and > 202 ha of land. Fifty eight percent of the survey participants responded, 82% of whom answered questions about their willingness to enroll at least part of their land in a brush reduction program. Property size and income from wildlife were found to be significant positive determinants and level of satisfaction with brush a significant negative determinant of respondents' willingness to enroll. To optimize public investments, it may be preferable to maximize the area enrolled in a brush removal program by targeting larger landowners who appear to be willing to enroll larger portions of their land without requiring compensation that exceeds their net cost of enrollment. Because land in the Edwards Plateau is being subdivided and purchased by people who do not depend on land-based income and who may be more tolerant of brush, public funds required to encourage landowner participation may increase over time.

Many North American grassland bird populations appear to be declining, which may be due to changes in grazing regimes on their breeding areas. Establishment of water developments and confining cattle (Bos taurus L.) to small pastures often minimizes spatial heterogeneity of cattle forage consumption, which may lead to uniformity in vegetative structure. This increased uniformity may provide suitable habitat for some bird species but not others. We assessed how cattle use, vegetative structure, and bird population densities varied with increasing distance from water developments (0–800 m) on the Little Missouri National Grassland (LMNG) in North Dakota. Lark buntings (Calamospiza melancorys Stejneger), which are typically associated with low vegetative cover, decreased with increasing distance from water developments. Horned larks (Eremophila alpestris L.), also a low-cover associate, followed a similar but weaker trend. Densities of another low-cover associate as well as moderate- and high-cover associates were not related to distance from water. Vegetative height-density and litter depth increased by 50 and 112%, respectively, while cowpie cover and structural variability decreased by 51 and 24%, respectively, with distance from water. Confidence interval overlap was common among all measures, showing substantial variability among study sites. Our results indicate cattle use is higher closer to water developments, and this pattern may positively affect the densities of lark buntings and horned larks. The absence of density gradients in the other bird species may be due to the paucity of locations > 800 m from water on the LMNG.

Mourning dove (Zenaida macroura L.) densities were determined using strip census techniques over a 2-year period (spring 1996 to winter 1998) on pastures in early-, mid-, and late-seral ecological condition. This study was conducted on the Chihuahuan Desert Rangeland Research Center and adjacent Bureau of Land Management rangelands in south-central New Mexico on 6 adjoining pastures that were similar in terrain and shape. Mourning dove densities pooled across sampling periods (8) were different (P < 0.10) on pastures in mid- and early-seral condition. They averaged 10.3, 33.9, and 7.2 birds km⁻² on pastures in late-, mid- and early-seral condition, respectively. Leatherleaf croton (Croton pottsii Lam.), the primary mourning dove food on all study pastures, was more abundant (P < 0.10) on late- and mid-seral pastures than on early-seral pastures. Therefore, heavy livestock grazing may adversely affect mourning dove populations in the Chihuahuan Desert by depleting leatherleaf croton. Autumn perennial grass cover and standing biomass differed (P < 0.10) among seral stages. More optimal interspersion of bare ground and perennial grasses may further explain why mid-seral rangelands tend to favor mourning doves. Our study shows mourning doves in the Chihuahuan Desert prefer moderately grazed, mid-seral rangelands over heavily grazed, early-seral rangelands.

Post-fire forage growth is known to be a strong attractant for large herbivores. However, fire has generally been avoided as a grazing distribution tool for fear of localized over utilization of forage resources. Our objectives were to examine whether forage utilization was affected by season of burn, determine cattle grazing preference for burned sites relative to non-burned sites, determine forb response to patch burning, and describe the relationship between end-of-season standing crop and distance from burned sites. Sixteen, 4-ha plots were burned in mid-November or mid-April and left exposed to cattle grazing for the duration of the growing season. Burn treatments were blocked within pastures to allow individual herds access to fall-burned, spring-burned, and non-burned sites. Standing crop estimates for grasses, forbs, and total herbage were made in September by clipping on burned sites and at 50, 100, 200, 400, and 800 m distant from the plot's edge. Standing crop was also sampled in exclosures on burned and non-burned sites. Cattle showed no preference for one burn season over the other. Cattle were strongly attracted to burned sites, reducing grass standing crop 78% within burns compared to 19% outside the influence of burns. Grass standing crop decreased in a predictable manner with proximity to burned plots. Forbs increased 60% to 1,095 kg ha⁻¹ on grazed burned plots, but were unaffected by distance from burns. Patch burning can be employed as an effective, inexpensive grazing distribution tool.

Management of feral horses grazing on Atlantic and Gulf coast barrier islands requires information on seasonal habitat preferences and distribution of important forage species to maintain stable populations and prevent destruction of fragile island ecosystems, particularly as coastal development further restricts free range. Counts from seasonal aerial surveys of Currituck Banks, N.C. were used to determine whether particular habitats were used more or less than would be expected by chance. On-ground observations were used to determine the relative intensity of grazing on vegetation by habitat and season. Feral horses showed seasonal preferences for particular forage species and habitat types. Horses grazed upon at least 16 graminoid and 5 forb species across 6 identified habitat types covering 4,619 ha. In late winter, Maritime Forest was used significantly more than expected while Tidal Freshwater Marsh was used less than expected. In spring, all habitats were used in the proportion expected based on availability. In early summer, Wet Grassland was preferentially used while Dry Grassland was preferentially avoided. The relative degree of exposure from wind may explain why horses spent less time than expected in exposed marshes during winter and more time than expected in forest. The availability of fresh water and hydrophytes may explain why horses spent more time than expected in Wet Grassland in summer and less time than expected in Dry Grassland. Seasonal habitat preferences should be considered when managing for ecosystem sustainability of feral horses on barrier islands.

The n-alkanes in plant cuticular wax have been used as markers for estimating the species composition of herbivore diets, but the long-chain fatty alcohols (LCOH) of plant wax may also be useful. The objective of this research was to assess if LCOH contributed extra information to differentiate plant species, compared with n-alkanes only. We used 3 data sets consisting of n-alkane and LCOH concentrations of plant species occurring in pastures of New South Wales, Australia. We used Principal Component Analysis (PCA) to summarise the data for n-alkane and LCOH concentrations obtained for the species in these data sets. The first 3 principal components explained 86 to 93% and 75 to 99% of the variance in n-alkane and LCOH concentrations, respectively. Orthogonal Procrustes Rotation (OPR) was then used to compare the results of PCA conducted with n-alkane and LCOH data, with a view to establishing whether LCOH provided discriminatory information in addition to that provided by the n-alkanes. Results of OPR indicated that this was so for all 3 data sets, and suggested that the LCOH would be useful additional markers for discriminating between plant species. We tested this by using Discriminant Analysis and cross-validation procedures in 2 data sets to distinguish between defined species groups of C₃ grasses, C₄ grasses, clovers and Lotus spp. The discrimination between these categories and the proportion of plant species correctly classified into the defined categories was better when using n-alkanes and LCOH together, compared with alkanes alone. Our results indicate that LCOH provided additional information that could be used for distinguishing plant species as part of estimating the species composition of herbivore diets.

Revegetation and sustainable cattle grazing are major objectives in the reclamation of mine tailings at the Highland Valley Copper mine in British Columbia, Canada. A total of 84 cow-calf pairs grazed forage extremely high in molybdenum (Mo) for 11 weeks in the summer and fall for 3 consecutive years (1999–2001). The average stocking rate was 0.63 ha AUM⁻¹. The animals' diet consisted primarily of alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.) containing 100–400 ppm Mo. Both cows and calves showed adequate daily gains of 0.78 kg head⁻¹ day⁻¹ and 1.33 kg head⁻¹ day⁻¹, respectively. Uptake of Mo was demonstrated by elevated levels of Mo in rumen contents and feces. Clinical signs of Mo toxicity were observed in less than half of the cows and in only a few calves. Clinical signs included a stiff shuffling gait, watery diarrhea, and a rough hair coat. Lameness, the primary sign, was resolved in all animals by the end of each trial. Diarrhea was also resolved by the end of the trial and hair coats returned to normal by the following spring. The onset and severity of the affliction appeared to be related to prevailing moisture conditions, which may have affected Mo availability in forage. Some affected animals were treated with Cu injections to no avail. Liver biopsies and serum samples showed marginal to adequate copper (Cu) levels but potentially toxic levels of Mo. In the third year of the trial, Cu-containing boluses were employed but they did not prevent the onset of clinical signs.

The effect of cattle grazing on the genetic structure of native grass populations has received little attention. We investigated the effect of cattle grazing on genetic variation in Idaho fescue (Festuca idahoensis Elmer) using ISSR (inter-simple sequence repeat) DNA markers. The ISSR markers are hypervariable and are generally interpreted as being selectively neutral. Idaho fescue tillers were sampled from inside (N = 31) and outside (N = 34) a 64-year-old cattle exclosure in southeastern Oregon. We extracted DNA and used 2 ISSR primers to determine the genotypes for grazed and ungrazed plants at 60 variable loci. No statistically significant differences were observed between grazed and ungrazed samples for percent polymorphic loci (grazed = 85%; ungrazed = 80%), mean expected heterozygosity (grazed = 0.1393; ungrazed = 0.1365), or for a measure of loci dissimilarity (grazed = 0.506; ungrazed = 0.536). We also found that the ungrazed individuals sampled inside the exclosure were not significantly genetically differentiated from the grazed individuals sampled outside the exclosure (G_st = 0.0008 averaged across all loci). Our results differ from past studies that found demographic and physiological differences between Idaho fescue inside and outside of grazing exclosures at the same site. Our results mirror those of other researchers who have also failed to detect genetic differences at marker loci in response to grazing. We propose that either the mechanisms that must be present to cause changes in neutral genetic variation are not affected by cattle grazing for Idaho fescue at this site, or that any effects of grazing on neutral genetic variation were overwhelmed by gene flow between the grazed and ungrazed samples.

Fertilizer application enable producers to influence pasture production. The effect of N fertilization on grass production and leguminous plant content of pasture and strategic N application has received much attention. Changing agricultural policies suggest that chemical fertilizer inputs may be diminished and that alternative sources of nutrients are desired. The aim of this study was to evaluate the effect of N and K fertilization on production, botanical composition, and forage mineral composition to gain some insight into what influence changing fertilization practices would have on pasture productivity. Three K and 3 N application rates were applied in a factorial design on a white clover (Trifolium repens L.)—perennial ryegrass (Lolium perenne L.) sward. Potassium and nitrogen application increased herbage production and had differential influences on botanical composition. Nitrogen decreased clover content in the pasture, whereas K increased the proportion and production of white clover. The effects of K application appeared later in the experiment than those associated with N. We concluded that K is very important for development and maintenance of white clover in pasture, which increases herbage and protein production. Nitrogen was associated with lesser amounts of N, P, K, and Mg in pasture, because of lesser amounts of clover in the sward. Changing fertilization practices will have definite influences on sward composition and pasture productivity. Any interpretation of pasture mineral content should take botanical composition changes into account.

A native shortgrass pasture downwind from a 25,000-head beef cattle feedyard near Bushland, Tex. degraded after the feedyard was stocked in 1970. Objectives were to determine pre-1970 vegetation, quantify current vegetation, and describe changes in vegetation, soil P and dust deposition with distance from the feedyard. Pre-1970 vegetation was documented with published measurements. In 2000, plant cover was quantified using 600 quadrats. Soil P, conserved in the local soil, was measured in soil samples from 119 locations. Dust was collected at 12 locations. From 1966–1972, cover was 18.8% blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Griffiths] and 7.4% buffalograss [Buchloe dactyloides (Nutt.) Engelm.]; the 2 species comprised 95% of vegetation cover. In 2000, perennial grass (75–99% blue grama) cover averaged 3.7% at < 150 m from the feedyard, and increased to 28% at > 525 m from the feedyard. Conversely, annual grass (67% Hordeum pusillum Nutt.) and annual forb [72% Kochia scoparia (L.) Schrad.] covers were 49% and 35% nearest the feedyard and decreased to 9% and 1%, respectively, at > 525 m. Over a similar distance, soil P decreased from 75 to 17 mg kg⁻¹. Dust deposition rate decreased with distance from the feedyard. Manure dust contribution to total dust ranged from negligible to 89%. It was estimated that 20–30 kg N ha⁻¹ year⁻¹ were deposited over 30 years to areas nearest the feedyard. Changes in vegetation and soil P were greatest at < 500 m from the feedyard. Vegetation and soil P were near values expected for shortgrass prairie at > 500 m downwind from the feedyard. The pattern of vegetation, soil fertility, and dust deposition gradients strongly suggested that the feedyard was the primary cause of the observed changes, although a direct causal link could not be established, and other factors, such as grazing, could have contributed to the observed changes.

Many range managers have suggested that clubmoss (Selaginella densa Rydb.) negatively alters the composition of seed banks and inhibits the establishment of plant species that decrease under improper grazing management. Alternatively it is possible that soil seed banks contain few seeds of decreaser species and composition of the seed bank is independent of clubmoss. The purpose of this study was to determine the composition and diversity of the soil seed bank in relation to the clubmoss cover and compositional characteristics of plant communities in the Northern Mixed Prairie of southwestern Saskatchewan. Cover of vascular plants was determined and soil seed bank samples were collected in 100 grazed plant communities. Soil seed bank samples were incubated in the laboratory with emerging seedlings being identified to species. Eight percent (SE ± 1.9) of emerging seedlings in the seed bank were decreasers, 73% (SE ± 2.8) were increasers, and 19% (SE ± 2.3) were invaders, indicating regeneration of decreaser species might be limited by low numbers of seeds in seed banks. Clubmoss cover was not correlated (P = 0.32 to 0.98) with species richness, species diversity, density of decreasers, density of increasers, density of invaders, and total seedling densities in the seed banks. Seed banks and plant communities shared few species as indicated by a low similarity index (x̄ = 0.31, SE ± 0.02). Species richness (x̄ = 3.6 species per 102 cm², SE ± 0.18) and diversity (x̄ = 1.00, SE ± 0.05) of seed banks were poorly correlated with characteristics of the plant communities. Range condition score was positively correlated (r = 0.17, P = 0.09) with total seedling densities in the soil seed bank, indicating more seedlings can potentially develop from the seed bank with increasing range condition of plant communities. We reject the hypothesis that clubmoss negatively affects the composition of seed banks. Mechanically disturbing plant communities to control clubmoss is predicted to lead to plant communities that are dominated by increasers and/or invaders. Managing for production of seeds by desired species should be a priority in promoting establishment of desired species.

The objective of this study was to simultaneously evaluate the impact of leafy spurge (Euphorbia esula L.) on plant species richness within and among a wide variety of vegetation types typical of the region. The study was conducted in Theodore Roosevelt National Park in southwestern North Dakota where 11 plant associations were identified as being particularly susceptible to invasion by leafy spurge. Representative infested and non-infested stands of the 11 associations were sampled using the protocol described by the National Vegetation Classification System. To evaluate the effects of leafy spurge infestation across a variety of vegetation types, the 11 associations were grouped into 1 of 4 general physiographic/vegetative units (floodplain, grassland, woodland, and shrubland). Species richness per sampled infested stand was reduced by an average of 51% (P ≤ 0.05) in 7 of the 11 sampled associations. Total species richness in infested stands averaged 61% less than species richness within their non-infested counterparts for 10 of the 11 associations. Thirty species common to the majority of the associations were completely absent from infested stands and classified as sensitive, whereas 25 were minimally impacted and classified as persistent species. The overall effects of leafy spurge on species richness is complex and probably involves patterns of soil moisture, nutrient conditions, and disturbance that influence the abundance and distribution of all alien plants in Theodore Roosevelt National Park. However, because of the considerable redundancy in species distribution among a wide variety of plant associations and an aggressive control program, overall species richness does not appear to be threatened by infestations of leafy spurge at this time.

This study investigated vegetation strategies for a fly ash landfill in a semi-arid environment. Ten plant species adapted to the local climate were initially evaluated for their germination characteristics in various mixtures of Tivoli fine sand, fly ash, and cattle manure. Alkali sacaton (native, Sporobolus airoides (Torr.) Torr.), blue grama (native, Bouteloua gracilis (H.B.K.) Lag. Ex Griffiths), a forage sorghum (variety Canex, Sorghum bicolor (L.) Moench), sand bluestem (variety Woodward, Andropogon hallii Hack.), and sideoats grama variety El Reno, Bouteloua curtipendula (michx.) Torr.) were selected for further evaluation. Concurrently, mixtures were evaluated to determine the effects of the soil amendments on soil saturated paste electrical conductivity (EC) and pH. The addition of even 50 g kg⁻¹ fly ash increased EC values above 4.0 dS m⁻¹, indicating salt tolerant species may be needed. Six mixtures were selected for use in a greenhouse study and for further study of moisture retention characteristics. Using an X/Y format, where X is fly ash content and Y is manure content (g kg⁻¹) and the balance of the mixture was Tivoli fine sand, those mixtures were 0/0, 200/0, 200/100, 200/200, 100/100, and 300/100. The addition of manure provided ample quantities of plant nutrients. Alkali sacaton was the only plant specie not adversely affected by the addition of fly ash. For biomass production, height, vigor and leaf tip burn, all remaining species had significantly better growth or ratings with 0/0 as compared to any other mixture. Soil moisture retention characteristics of the Tivoli fine sand can be significantly changed through amendment with fly ash or manure. Sixty cm of Tivoli sand was estimated to have the same available water holding capacity as 45 cm of 200/0, 39 cm of 200/100, 34 cm of 200/200, 47 cm of 100/100, and 33 cm of 300/100.

Site degradation occurs mainly through deterioration of the soil's capacity to capture and store water, as well as the loss of organic matter or the accumulation of salts or other toxic substances in the soil. This degradation process, leading to the reduction of the biotic potential of the site, is known as desertification. In this study, changes in bulk density, organic matter, and electrical conductivity are used as indicators of desertification in northeast Mexico. The hypotheses put forward here are that degradation processes are affecting extensive areas of the region, and that the type of processes and their magnitude differ according to specific land uses. Thirty-one sites under different land use systems (agriculture, rangeland, induced grassland, and a protected site) were sampled for bulk density, organic matter, and salinity. Soil samples for bulk density estimation were collected in 1996, 1997, and 1999, while those for organic matter and salinity were taken in 1993, 1997, and 1999. Soil bulk density and organic matter showed significant changes across time in rangeland sites. None of the sites showed significant changes in salinity. Organic matter was similar in agriculture, rangeland, and grassland sites across dates. Soil bulk density was similar in grasslands and rangelands and lower in agriculture sites. Values of organic matter were lower and those of soil bulk density were higher when compared to a protected native vegetation site.