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Resource distribution, habitat structure, and predators greatly influence spatial and temporal landscape use by prey species. The “risky places” hypothesis establishes prey will proactively respond to predators' presence based on habitat cues, whereas the “risky times” hypothesis predicts prey will reactively respond by increasing vigilance in the presence of predators regardless of habitat cues. We fit a multiscale, Bayesian species interaction occupancy model with detection/non‐detection data to evaluate black‐tailed jackrabbit (Lepus californicus) and eastern cottontail rabbit (Sylvilagus floridanus) habitat use in the presence and absence of coyotes (Canis latrans), American badgers (Taxidea taxus), and swift foxes (Vulpes velox). We also evaluated how species‐specific predator presence modified temporal activity patterns of prey. Jackrabbits decreased habitat use in areas with greater forage and opted to use areas with greater visibility when coyotes or swift foxes were present. However, cottontails used habitat in open areas with greater visibility when American badgers were present and all other predators absent, suggesting dissimilar habitat‐use patterns dictated by predator‐specific risks. Both lagomorph species are nocturnal with segregated peaks of activity compared with predators, suggesting fine‐scale temporal use partitioning. Our results provide insights into predator–prey dynamics across heterogenous landscapes in a multi‐predator system.

To anticipate the rapidly changing world resulting from global climate change, the projections of climate models must be incorporated into conservation. This requires that the scales of conservation be aligned with the scales of climate-change projections. We considered how conservation has incorporated spatial scale into protecting biodiversity, how the projections of climate-change models vary with scale, and how the two do or do not align. Conservation planners use information about past and current ecological conditions at multiple scales to identify conservation targets and threats and guide conservation actions. Projections of climate change are also made at multiple scales, from global and regional circulation models to projections downscaled to local scales. These downscaled projections carry with them the uncertainties associated with the broad-scale models from which they are derived; thus, their high resolution may be more apparent than real. Conservation at regional or global scales is about establishing priorities and influencing policy. At these scales, the coarseness and uncertainties of global and regional climate models may be less important than what they reveal about possible futures. At the ecoregional scale, the uncertainties associated with downscaling climate models become more critical because the distributions of conservation targets on which plans are founded may shift under future climates. At a local scale, variations in topography and land cover influence local climate, often overriding the projections of broad-scale climate models and increasing uncertainty. Despite the uncertainties, ecologists and conservationists must work with climate-change modelers to focus on the most likely projections. The future will be different from the past and full of surprises; judicious use of model projections at appropriate scales may help us prepare.

Grass management has been used for many years at airports in an attempt to reduce numbers of birds and other wildlife and the collisions with aircraft associated with them. We evaluated the impacts of grassland alteration by mowing and fi re on the abundance, diversity, and frequency of birds using 1 control and 2 experimental grass plots from 2009 to 2010 on a U.S. Army airfield in Colorado located in short-grass prairie. Density of breeding birds was highest in the mowed plot. Numbers of birds observed in 34 surveys conducted during the non-breeding season in the burned (x = 41) and mowed (x = 24) plots were greater than in an unmanaged control (x = 7) plot. Bird species diversity in the nonbreeding season was greatest in the control plot. Horned larks (Eremophila alpestris) was the most frequently observed bird species and occurred in high numbers on the burned and mowed plots, possibly because of its preference for short vegetation and bare ground. This species is recognized as hazardous to aircraft in part because of its habit of forming large flocks in the nonbreeding season. All 3 study plots were dominated by grasses and forbs, with minimal shrub and cactus cover. Litter cover was greatest on the control plot, while the burned plot had the greatest coverage of bare ground. Results from this study are limited because the small size of the airfield precluded placement of multiple treatment plots. Additional study in larger airfields with multiple treatment plots would be required before management recommendations regarding the use of fi re and mowing can be made for airfields in areas with short-grass prairie.

Soil heat flux is examined using a new method considering soil thermal conduction and convection processes. Using this method, we determine that soil heat fluxes owing to soil thermal conduction and convection were significant for the Naqu site in the summer of 1998. Experimental analyses of the surface energy balance are given.

Alien invasions typically reduce species richness of habitats, but few studies have examined their effects on species turnover, the difference in species composition between localities. Agropyron cristatum (L.) Gaertn. (crested wheat grass) has been planted on 6-10 million ha of North American prairie, and is invading native prairie. We studied the invasion of A. cristatum into native prairie by measuring species composition along a gradient from maximum to minimum A. cristatum abundance. As A. cristatum increased, the abundance of most common native species decreased, but one appeared to be unaffected (Bouteloua gracilis (H.B.K.) Lag.), and another (Poa sandbergii Vasey) increased. The effect of A. cristatum on species turnover was investigated by examining species-area curves for areas from 0.5 m2to 8.0 m2. Species diversity was reduced by 35% at high A. cristatum abundances at all areas. A. cristatum reduced the intercept of the species-area curve, but not the slope, suggesting that A. cristatum affected species turnover proportionally in all areas and habitats. This unusual result may indicate a homogeneous environment where species are distributed randomly. A. cristatum produced almost twice as many seeds as all native grasses combined. The number of seeds collected of native grasses and A. cristatum was highly correlated with the number of seed heads immediately nearby, but not with transect position. This suggests most seeds were dispersed over distances less than 5 m. In sum, the invasion of native prairie by A. cristatum might be related to high rates of seed production, and has the effect of decreasing species turnover by reducing the intercept of the species-area curve.

Grass management has been used for many years at airports in an attempt to reduce numbers of birds and other wildlife and the collisions with aircraft associated with them. We evaluated the impacts of grassland alteration by mowing and fire on the abundance, diversity, and frequency of birds using 1 control and 2 experimental grass plots from 2009 to 2010 on a U.S. Army airfield in Colorado located in short-grass prairie. Density of breeding birds was highest in the mowed plot. Numbers of birds observed in 34 surveys conducted during the non-breeding season in the burned (x̄ = 41) and mowed (x̄ = 24) plots were greater than in an unmanaged control (x̄ = 7) plot. Bird species diversity in the nonbreeding season was greatest in the control plot. Horned larks (Eremophila alpestris) was the most frequently observed bird species and occurred in high numbers on the burned and mowed plots, possibly because of its preference for short vegetation and bare ground. This species is recognized as hazardous to aircraft in part because of its habit of forming large flocks in the nonbreeding season. All 3 study plots were dominated by grasses and forbs, with minimal shrub and cactus cover. Litter cover was greatest on the control plot, while the burned plot had the greatest coverage of bare ground. Results from this study are limited because the small size of the airfield precluded placement of multiple treatment plots. Additional study in larger airfields with multiple treatment plots would be required before management recommendations regarding the use of fire and mowing can be made for airfields in areas with short-grass prairie.

The authors used a case-study methodology to explore the perceptions of 30 9th-grade biology students relative to black-tailed prairie dogs. The case study, which involved classroom- and field-based experiences that focused on black-tailed prairie dogs, revealed 3 major themes: apathy, egocentrism, and naive conceptions. The authors had hoped that these experiences would promote a change in attitude and understanding among the participants relative to black-tailed prairie dogs. Given the findings of this study and the current literature, the authors provide suggestions for educators attempting to promote change in attitude toward target species of wildlife.

• In perennial grasslands, the below-ground population of meristems (bud bank) plays a fundamental role in plant population dynamics. Here, we tested the 'meristem limitation hypothesis' prediction - that bud banks increase along an increasing precipitation/productivity gradient in North American grasslands - and assessed the seasonal dynamics of bud banks. • We sampled bud and stem populations quarterly at six sites across a 1100 km gradient in central North America. • Bud banks increased with average annual precipitation, which explained 80% of the variability between the sites. In addition, seasonal changes in grass bud banks were surprisingly similar across a 2.5-fold range in precipitation and a 4-fold range of productivity: densities peaked in March, decreased in June and increased slightly in September. • Increasing meristem limitation may constrain vegetation responses to inter-annual changes in resources. An important consequence of this is that biomes with large bud banks may be the most responsive to environmental change. If meristem limitation represents an important constraint on productivity responses to environmental variability, then bud banks must be considered in developing predictive models for grassland responses to environmental change.

In temperate grasslands, the relative importance of above‐ground competition for light compared to below‐ground competition for water and nutrients is hypothesized to increase with increasing precipitation. Thus, competition for light is likely to exert an increasing influence on canopy structure and species composition as precipitation increases. We quantified canopy structure, light availability and changes in species composition at seven sites across the central grassland region of the United States to determine how these properties change across a precipitation gradient. Across the region, there was a disproportionate increase in leaf area and canopy height with increasing precipitation, indicating that plants become taller and leafier across the gradient. Leaf area index increased by a factor of 12 across the gradient while above‐ground net primary productivity increased by a factor of only 5.5. As precipitation increased, there was decreased light availability at the soil surface, increased seasonal variability in light transmission, increased biomass and leaf area at higher canopy layers and an increased proportion of tallstatured species. These observed changes in canopy structure support the prediction that competition for light increases in importance with increasing precipitation.

Few empirical data exist to examine the influence of regional scale environmental gradients on productivity patterns of plant species. In this paper we analyzed the productivity of several dominant grass species along two climatic gradients, mean annual precipitation (MAP) and mean annual temperature (MAT), in the Great Plains of the United States. We used climatic data from 296 weather stations, species production data from Natural Resource Conservation Service rangeland surveys and a geographic information system to spatially integrate the data. Both MAP and MAT were significantly related to annual above-ground net primary production (ANPP). MAP explained 54 % to 89 % of the variation in ANPP of two C4 short-grasses, Bouteloua gracilis and Buchloë dactyloides, and two C4 tall-grasses, Andropogon gerardii and Schizachyrium scoparium (= Andropogon scoparius). MAT explained 19 % to 41 % of the variation in ANPP of two C4 grasses, B. gracilis and B. dactyloides, and 41 % to 66 % of the variation in ANPP of two C3 grasses, Agropyron smithii and Stipa comata. ANPP patterns for species along both gradients were described by either linear, negative exponential, logistic, normal or skewed curves. Patterns of absolute ANPP (g/m2) for species differed from those of relative ANPP (%) along the MAP gradient. Responses were similar for species with common functional characteristics (e.g. short-grasses, tall-grasses, C3, C4). Our empirical results support asymmetric responses of species to environmental gradients. Results demonstrate the importance of species attributes, type of environmental gradient and measure of species importance (relative or absolute productivity) in evaluating ecological response patterns.