Dense Shrub Cover Research Articles

Livestock Detection and Counting in Kenyan Rangelands Using Aerial Imagery and Deep Learning Techniques

Accurate livestock counts are essential for effective pastureland management. High spatial resolution remote sensing, coupled with deep learning, has shown promising results in livestock detection. However, challenges persist, particularly when the targets are small and in a heterogeneous environment, such as those in African rangelands. This study evaluated nine state-of-the-art object detection models, four variants each from YOLOv5 and YOLOv8, and Faster R-CNN, for detecting cattle in 10 cm resolution aerial RGB imagery in Kenya. The experiment involved 1039 images with 9641 labels for training from sites with varying land cover characteristics. The trained models were evaluated on 277 images and 2642 labels in the test dataset, and their performance was compared using Precision, Recall, and Average Precision (AP0.5–0.95). The results indicated that reduced spatial resolution, dense shrub cover, and shadows diminish the model’s ability to distinguish cattle from the background. The YOLOv8m architecture achieved the best AP0.5–0.95 accuracy of 39.6% with Precision and Recall of 91.0% and 83.4%, respectively. Despite its superior performance, YOLOv8m had the highest counting error of −8%. By contrast, YOLOv5m with AP0.5–0.95 of 39.3% attained the most accurate cattle count with RMSE of 1.3 and R2 of 0.98 for variable cattle herd densities. These results highlight that a model with high AP0.5–0.95 detection accuracy may struggle with counting cattle accurately. Nevertheless, these findings suggest the potential to upscale aerial-imagery-trained object detection models to satellite imagery for conducting cattle censuses over large areas. In addition, accurate cattle counts will support sustainable pastureland management by ensuring stock numbers do not exceed the forage available for grazing, thereby mitigating overgrazing.

Influence of abiotic factors on habitat selection of sympatric ocelots and bobcats: testing the interactive range-limit theory

AimMitigating the effects of extreme conditions is a mechanism that can structure the activity patterns and habitat selection of a species and may particularly impact species at the extremes of their geographic distribution. Furthermore, changing climate patterns have the potential to influence biotic interactions between species in novel ways. As two species at the edges of their northern and southern distributions, respectively, ocelots and bobcats may face unique pressure compared to individuals in more central portions of their range. Our objective was to describe the selection of thermal cover by ocelots and bobcats to examine whether partitioning of thermal resources was occurring or if this was a source of potential interspecific competition.LocationWe monitored eight ocelots and 13 bobcats in South Texas, USA.MethodsWe compared selection within, above, and below their estimated thermoneutral zones to examine the effect of varying temperature on habitat selection. Additionally, we stationed 130 black globe thermal sensors to describe the thermal properties of the various cover types.ResultsWe observed variation in habitat selection across temperatures and species. Ocelots and bobcats selected for shrub cover and vertical canopy cover when cold stressed. When heat stressed, both species avoided bare ground and selected for higher vertical canopy cover and were located closer to dense cover. Black globe measurements revealed differences in environmental temperature across cover types, with forest and shrub cover significantly lower than herbaceous or bare ground.Main conclusionsChanging climates may influence interspecific competition and alter areas of sympatry through range shifts. Our results stress the importance of dense shrub cover and forested canopy as thermal refuge for ocelots and bobcats and suggest that abundant vegetation may mitigate the effects of interspecific competition during lower temperatures and niche partitioning may reduce interspecific competition during upper temperature limits, providing support for the interactive range-limit theory.

Effects of Shrub Encroachment on Carbon Assimilation and Growth of Mediterranean Cork Oak Trees Depend on Shrub Cover Density

Mediterranean ecosystems are threatened by climate change and shrub encroachment. An increase in shrub cover can intensify the competition for water, aggravating the impacts of drought on ecosystem functioning. The effects of shrubs can be positive or negative, depending on the shrub species and density. We used a Mediterranean cork oak (Quercus suber) woodland to investigate the effects of increasing gum rockrose (Cistus ladanifer) cover on leaf carbon assimilation (Amax) and tree growth. The experiment consisted of a gradient of shrub cover, with four treatments: control, LD, MD, and HD, with 0%, 25%, 45%, and maximum shrub cover (>90%), respectively. Increasing shrub cover significantly decreased Amax in trees from HD (−15%) compared to control treatment, with intermediate effects on trees from LD (−5%) and MD (−12%). There was a large variability in tree growth, resulting in no significant effects of shrub cover, despite higher trunk diameter relative increments in LD (+40%), and lower in MD (−17%) and HD (−32%) compared to the control. The results indicate that a dense shrub cover (>90%) affected cork oak carbon assimilation and growth, while a low-to-medium shrub cover (≤45%) only induced mild intermediate effects. This information is important for the effective management of shrub density to improve the health and productivity of cork oak woodlands.

Control of Mosses on Water Flux in an Alpine Shrub Site on the Qilian Mountains, Northwest China.

Mosses are an important component of the alpine shrub, but little is known about their contribution to ecosystem water and energy exchange, especially potential opportunities for alpine shrub expansion under a warming climate. We studied the role of mosses in alpine shrub evapotranspiration by conducting herb and moss removal experiments with different Potentilla fruticosa L. shrub coverage in the Qilian Mountains, Northwest China. The understory evapotranspiration was measured using lysimeters in different shrub coverage (dense shrub cover, medium shrub cover, and thin shrub cover) during the growing season of 2012. The understory evapotranspiration is about 1.61 mm per day in the control treatment (intact moss and herbs) during the growing season, and the evapotranspiration rates differed significantly between canopy covers. We found a 22% increase in evapotranspiration losses after removing the moss layer compared to the control treatment lysimeter with an intact moss layer in the shrub site. This suggests that most of the understory evaporation originated from the organic layer underlying the moss layer. Given this study's large moss evaporation rates, understory contributions cannot be ignored when interpreting eddy covariance data for the whole alpine ecosystem. Our results show that mosses may exert strong controls on understory water fluxes in alpine shrub meadow ecosystems and suggest that changes in moss cover may have significant consequences for season frozen soil thaw.

Northern bobwhite select for shrubby thickets interspersed in grasslands during fall and winter.

Resource selection is a key component in understanding the ecological processes underlying population dynamics, particularly for species such as northern bobwhite (Colinus virginianus), which are declining across their range in North America. There is a growing body of literature quantifying breeding season resource selection in bobwhite; however, winter information is particularly sparse despite it being a season of substantial mortality. Information regarding winter resource selection is necessary to quantify the extent to which resource requirements are driving population change. We modeled bobwhite fall and winter resource selection as a function of vegetation structure, composition, and management from traditionally (intensively) managed sites and remnant (extensively managed) grassland sites in southwest Missouri using multinomial logit discrete choice models in a Bayesian framework. We captured 158 bobwhite from 67 unique coveys and attached transmitters to 119 individuals. We created 671 choice sets comprised of 1 used location and 3 available locations. Bobwhite selected for locations which were closer to trees during the winter; the relative probability of selection decreased from 0.45 (85% Credible Interval [CRI]: 0.17-0.74) to 0.00 (85% CRI: 0.00-0.002) as distance to trees ranged from 0-313 m. The relative probability of selection increased from near 0 (85% CRI: 0.00-0.01) to 0.33 (85% CRI: 0.09-0.56) and from near 0 (85% CRI: 0.00-0.00) to 0.51 (85% CRI: 0.36-0.71) as visual obstruction increased from 0 to 100% during fall and winter, respectively. Bobwhite also selected locations with more woody stems; the relative probability of selection increased from near 0.00 (85% CRI: 0.00-0.002) to 0.30 (85% CRI: 0.17-0.46) and near 0.00 (85% CRI: 0.00-0.001) to 0.35 (85% CRI: 0.22-0.55) as stem count ranged from 0 to 1000 stems in fall and winter, respectively. The relative probability of selection also decreased from 0.35 (85% CRI: 0.20-0.54) to nearly 0 (85% CRI: 0.00-0.001) as percent grass varied from 0 to 100% in fall. We suggest that dense shrub cover in close proximity to native grasslands is an important component of fall and winter cover given bobwhite selection of shrub cover and previously reported survival benefits in fall and winter.

Group selection silviculture for converting pine plantations to uneven-aged stands

Recent years have witnessed an increased interest in managing and restoring southern pine stands using uneven-aged silvicultural strategies, that rely on natural regeneration. Group selection harvests are regarded as an effective approach to induce natural regeneration and convert pine plantations to uneven-aged stands. In a wet flatwoods site in north-west Florida, we characterized natural regeneration (density, size, spatial distribution, hot spots) of slash pine (Pinus elliottii Englm.) eight years following group selection harvests and one year following prescribed fire in mature slash pine plantations. Our study utilized a long-term, operational scale experiment consisting of circular harvest group openings of four different sizes (0.1, 0.2, 0.4, 0.8 ha), each replicated three times. In all group openings, we stem mapped all regeneration > 1.37 m in height and measured their diameter at breast height (dbh) and total height. We also estimated understory shrub cover in the group openings. Overall, slash pine regeneration response was highly variable across group opening sizes and ranged between 150 (in 0.1 ha group openings) to 670 stems ha−1 (in 0.8 ha group openings). On average, 468 ± 105 (mean ± standard error) stems ha−1 were found in the group openings. Group opening size had no significant effect on regeneration density or size (ɑ =0.05). Position within group opening, however, had a significant effect on regeneration density and height, with higher density occurring in group opening centers and taller stems in northern positions. Shrub cover decreased with increasing group opening size and was lowest in northern positions. Dense shrub cover (60–100%) was associated with greater regeneration density. The areas with dense shrub cover appeared to have escaped prescribed fire and experienced lower seedling mortality. Spatial point pattern analysis showed aggregation of regeneration for all group sizes across all distances. Regeneration hotspots were mostly central and southern positions in group openings. Earlier observations of our study suggest that the group selection harvesting may be a suitable approach to regenerate slash pine and add an age-class (regeneration cohort) to even-aged stands in wet flatwoods sites.

Rusty Blackbirds select areas of greater habitat complexity during stopover

Abstract The Rusty Blackbird (Euphagus carolinus) is a widespread, uncommon migrant that has experienced heavy population declines over the last century. This species can spend over a quarter of their annual cycle on migration, so it is important to determine their habitat requirements during stopover events to inform effective conservation planning. We assessed their habitat selection at an important stopover site in northern Ohio during both fall and spring migration. Since stopover habitat selection is scale-dependent, we investigated both patch-scale (between patches) and fine-scale (within a patch) selection using radio telemetry to locate foraging and roosting flocks, and compared habitat variables between used and available points across the study site. At the patch scale, we found that birds preferred dogwood–willow swamp, low-lying forest patches, and areas of greater habitat complexity for foraging in both seasons. At the fine scale, spring migrants foraged closer to habitat edges than random, and preferred areas with more wet leaf litter and shallow water, and less grass cover. Fall migrants also preferred shallow water and leaf litter cover, and avoided areas with dense grass, forbs, and herbaceous shrub cover. By contrast, birds consistently roosted in dense stands of emergent Phragmites or Typha marsh, suggesting that the best stopover or staging sites are those with a matrix of different wetland habitats. Although the migratory range of Rusty Blackbirds is currently dominated by agricultural development, our results suggest that fragmented landscapes can still provide adequate habitat for migrants if the available land is managed for a variety of wet habitat types.

Using willow microcuttings for ecological restoration: An alternative method for establishing dense plantations

This experimental study presents an innovative method for establishing a willow (Salix spp.) shrub vegetation cover on disturbed sites in North America. Willow microcuttings of Salix miyabeana ‘SX61’, S. eriocephala ‘S25’ and S. purpurea ‘Fish Creek’ were selected to test the potential of shortened willow cuttings. We evaluated the effect of three factors related to microcutting assemblages (monoculture and polyculture), the presence or absence of a companion herbaceous plant and two types of substrate (same soil, but one with compost and one without). The objectives were to assess 1) the potential growth of willow microcuttings in open site conditions, 2) the influence of soil amendments on the establishment of willow microcuttings and 3) the influence of diversity on biotic resistance. The results showed a greater establishment rate, stem height and number of shoots per microcutting without the presence of an herbaceous plant. The plots planted without compost showed better establishment rates, especially those in the polyculture plots. The presence of compost increased the production of number of shoots per microcutting and tended to increase stem height. The presence of an herbaceous plant was related to higher plant cover, but no relationship with biotic resistance was observed. Although willow cover did not significantly affect relative growth of undesirable tree species seedlings (Betula populifolia and Acer rubrum), we observed that plant cover tended to reduce the relative growth rate. Consequently, this preliminary test of using microcuttings as an alternative approach to establishing a dense shrub cover showed good potential to restore disturbed sites and limit tree encroachment in open sites, reducing environmental and economic costs.

Ecohydrological change following rewetting of a deep‐drained northern raised bog

AbstractRestoration of degraded peatland ecosystems (by rewetting) is undertaken to bring back key ecosystem services. However, the restoration process can have a range of ecohydrological effects, due to the associated physical and biogeochemical disturbance. In the case of northern peatlands drained by large and deep ditches, the rewetting effects are relatively unknown. The raised bog Grande plée Bleue (1,500 ha) is one of the largest pristine bogs in the St‐Lawrence lowlands in North America; however, it contained an old (>60 years), 750 m long, 3.5 m deep, and 8 m wide ditch. Rewetting of the area affected by the ditch was carried out by the construction of six dams at 40 cm elevation intervals and felling of all trees (with diameter at breast height >10 cm) within 30 m. Water table was restored to levels similar to intact bog reference sites, only at elevation differences up to 17 cm from the nearest lower dam, while rewetting did not affect pore‐water chemistry. Five to 6 years post‐rewetting, the cover of both pioneer mosses, and late successional mosses (Sphagnum) had not changed significantly compared with pre‐rewetting. This may have been due to the presence of dense shrub cover. For more effective ecohydrological restoration, dams should be spaced at smaller elevation intervals (e.g., every 20 cm of elevation or less), to allow recovery of water table along the entire length of the ditch, and vegetation introduction using the moss layer transfer technique may accelerate Sphagnum recruitment, especially in the few first metres from the ditch.

Talus slope characterization in Tasiapik Valley (subarctic Québec): Evidence of past and present slope processes

Topographic, granulometric, morphometric, petrographic and vegetation surveys were conducted on the slopes of Tasiapik Valley, near Umiujaq (Nunavik), to document mass wasting processes and their geomorphological impact. Talus slopes, widespread at the foot of the steep rockwalls of Tasiapik Valley, are an important landscape feature in the area. The lithology of the slope deposits attest their local origin, namely the result of rockfalls coming from the adjacent wall. Locally, poor vegetation covering the clasts exhibits recently fallen debris; elsewhere, dense shrub cover has colonized the slopes demonstrating the low activity nowadays. On-going periglacial processes have led to extensive dismantling of the rockface, enabling for debris supply. Following the last deglaciation, paraglacial processes have potentially favoured slope instabilities. The use of automatic cameras during the winter 2017–2018 resulted in the observation of many snow-avalanche events; however few rockfall events have been observed. Spring snow avalanches have carried rock debris to the talus at the foot of the slope; snow also enabled debris redistribution on the slopes.

Runoff and Solute Outputs under Different Land Uses: Long-Term Results from a Mediterranean Mountain Experimental Station

Water availability and quality in Mediterranean environments are largely related to the spatial organisation of land uses in mountain areas, where most water resources are generated. However, there is scant data available on the potential effects of land use changes on surface water chemistry in the Mediterranean mountain region. In order to address this gap in the research, this study investigates the effects of various mountain Mediterranean land covers/land uses on runoff water yielded and water chemistry (solute concentrations and loads) using data from the Aísa Valley Experimental Station (Central Pyrenees) for a long-term period (1991–2011). Nine land covers have been reproduced in closed plots, including dense shrub cover, grazing meadows, cereal, fallow land, abandoned field, shifting agriculture (active and abandoned) and 2 burned plots (one burned in 1991 and the second one burned twice in 1993 and 2001). Results show that all solute concentrations differed among land uses, with agricultural activity producing significantly higher solute loads and concentrations than the other types. Two groups have been identified: (i) the lowest solute concentrations and the smallest quantities of solute loads are recorded in the dense shrub cover, the plot burned once (at present well colonized with shrubs), meadows and abandoned field plots; (ii) the plot burned twice registered moderate values and the highest solute concentrations and loads are found in cereal, fallow land and shifting agriculture plots. Water chemistry is clearly dominated by Ca2+ and HCO3− concentrations, whereas other solutes are exported in very low quantities due to the poor nutrient content of the soil. These results complete the information published previously on soil erosion under different land uses in this experimental station and help to explain the evolution of land cover as a consequence of shifting agriculture, cereal farming on steep slopes and the use of recurrent fires to favour seasonal grazing. They also suggest that promoting the development of grazing and cutting meadows is a good strategy to reduce not only soil erosion but also the loss of nutrients.

Describing vegetation characteristics used by two rare forest-dwelling species: Will established reserves provide for coastal marten in Oregon?

Forest management guidelines for rare or declining species in the Pacific Northwest, USA, include both late successional reserves and specific vegetation management criteria. However, whether current management practices for well-studied species such as northern spotted owls (Strix occidentallis caurina) can aid in conserving a lesser known subspecies—Humboldt martens (Martes caurina humboldtensis)–is unclear. To address the lack of information for martens in coastal Oregon, USA, we quantified vegetation characteristics at locations used by Humboldt martens and spotted owls in two regions (central and southern coast) and at two spatial scales (the site level summarizing extensive vegetation surveys and regionally using remotely sensed vegetation and estimated habitat models). We estimated amount of predicted habitat for both species in established reserves. If predicted overlap in established reserves was low, then we reported vegetation characteristics to inform potential locations for reserves or management opportunities. In the Central Coast, very little overlap existed in vegetation characteristics between Humboldt martens and spotted owls at either the site or regional level. Humboldt martens occurred in young forests composed of small diameter trees with few snags or downed logs. Humboldt martens were also found in areas with very dense vegetation when overstory canopy and shrub cover percentages were combined. In the South Coast, Humboldt martens occurred in forests with smaller diameter trees than spotted owl sites on average. Coastal Humboldt martens may use stands of predicted high quality spotted owl habitat in the Pacific Northwest. Nonetheless, our observations suggest that coastal Humboldt martens exist in areas that include a much higher diversity of conifer size classes as long as extensive dense shrub cover, predominantly in the form of high salal and evergreen huckleberry, are available. We suggest that managers consider how structural characteristics (e.g., downed logs, shrub cover, patch size), are associated with long-term species persistence rather than relying on reserves based on broad cover types. Describing vegetation may partially describe suitability, but available prey or predation risk ultimately influence likelihood of individual Humboldt marten use. Guidelines for diversifying vegetation management, and retaining or restoring appropriate habitat conditions at both the stand level and regionally, may increase management flexibility and identify forest conditions that support both spotted owls and Humboldt martens.

Understanding Habitat Quality for Preble's Meadow Jumping Mouse: How Survival Responds to Vegetation Structure and Composition

AbstractHabitat loss is the primary conservation concern for many rare species; yet, it is unclear what habitat components are vital for the persistence of many rare species. The Preble's meadow jumping mouse Zapus hudsonius preblei (PMJM) was listed as Threatened under the Endangered Species Act because of habitat loss in Colorado and Wyoming. The PMJM is restricted to dense shrub cover and dense herbaceous vegetation along wetland and riverine systems. Although it is well established by researchers that PMJM infrequently leave these habitat types, it is unclear what riparian vegetation structure and composition is important to PMJM survival. We collected and analyzed a 14-y PMJM vegetation-monitoring data set and a PMJM mark–recapture data set to assess the influence of vegetation structure and composition on PMJM annual survival. Using individual, group, and site-specific covariates we estimated survival and evaluated the influence of such covariates on annual survival. Annual survival for PMJM was low (< 10%), increasing with body mass, grass cover, and shrub cover, and decreasing with meadow vole Microtus pennsylvanicus captures. The PMJM use of and occupation of dense riparian habitats may increase individual survival, and likely increases population persistence. Thus, habitat modifications that reduce grass cover and shrub regeneration, such as grazing, suburban development, and development-altered hydrology, will be detrimental to PMJM populations. Given the low annual survival of PMJM, it is important for conserving PMJM populations to minimize disturbances to the vegetation structure, composition, and density, and the hydrologic processes that support them.

Morphology and Genesis of Humus Profiles under Chaparral Shrubs in Southern California

Core Ideas Litter layers of chaparral soils differ dramatically under different plant species. The rate of litterfall, balanced by the rate of decomposition, influences the type of litter layers that develop. Macrofauna, such as earthworms, are inhibited by dry conditions and have minimal effects on litter layer characteristics. Chaparral is the predominant wildland ecosystem adjoining many urban areas of California. The litter layers under this dense shrub cover are important because they modify soil climate, support soil fauna, provide nutrients, and protect against soil erosion. The objectives of this study were: (i) to understand how the morphology of chaparral litter layers changes with depth under different shrub species, and (ii) to determine the influence of shrub species and associated macrofauna on the genesis of humus profiles. Research was conducted within mature chaparral stands (38 yr after fire) on the San Dimas Experimental Forest under four common chaparral species: chamise (Adenostoma fasiculatum H. & A.), hoaryleaf ceanothus (Ceanothus crassifolius Torr.), bigberry manzanita (Arctostaphylos glauca Lindl.), and scrub oak (Quercus dumosa Nutt.). Increased litter decomposition with depth was expressed as decreasing C/N ratios, proliferation of fungal hyphae, and degradation of characteristic leaf features. Mineral matter content also increased with depth in the humus profiles, resulting from mixing by soil fauna. Earthworm densities were low throughout the chaparral, caused by seasonal moisture limitations, and were insufficient to consume manzanita leaf litter effectively, leading to thicker humus profiles and the development of Mor‐type humus. Moder‐type humus forms, with thinner litter layers, were found under scrub oak and ceanothus. Chamise litter was classified as a Rhizomull because of minimal litter accumulation, resulting from low and roughly equivalent litterfall and decomposition rates. Unique characteristics of the chaparral species led to different humus profiles and humus forms but macrofauna were not an overriding genetic influence.

Factors affecting frog species richness in the Solomon Islands

Studies across large oceanic archipelagos often provide an opportunity for testing different processes driving patterns of species richness. Frogs are among the most abundant vertebrates in the Solomon Islands but little is known of the factors influencing their richness patterns. This study used modelling to determine important ecological and biogeographic factors affecting the species richness of frogs at multiple locations on major islands across the archipelago. Between March 2009 and August 2012, 16 frog species were recorded along 109 transects placed in coastal, lowland, ridge and montane forests across 13 islands. Mean species richness was higher in the North Solomon Islands arc (6.2 species) and decreased eastwards towards the New Georgia islands (4.7 species), and Malaita (3.2 species). A plausible explanation is that the North Solomon Islands arc is closest to New Guinea, a major centre of dispersal in the south-west Pacific. Coastal (4.6 species) and freshwater (4.8 species) forests had lower predicted species richness than lowland, ridge, and montane forest types (all with 6.2 species). In addition, more frogs were predicted in areas with thin leaf litter (6.2 species), dense shrub cover (7.7 species), and moist soils (7.7 species), which are characteristic of undisturbed forests. These results suggest that frog conservation activities in the Solomon Islands should target islands in the west with intact lowland, ridge, and montane forests. Specific knowledge of this nature is vital for amphibian conservation on tropical islands experiencing extensive habitat loss, habitat modification and widespread predicted climate change impacts.

Muscling into Meadows: A Preliminary Dendrochronological Analysis of Recent Conifer Encroachment in Mount Rainier’s Subalpine Meadows

A dramatic reconfiguration of the subalpine ecotone is underway in many mountainous regions. One of the changes occurring in subalpine ecosystems is the shrinking and fragmentation of subalpine meadows. In July 2016, we investigated the encroachment of conifers into a subalpine meadow on the south side of Mount Rainier as part of the North American Dendroecological Fieldweek, a unique experiential learning program dedicated to training participants in the theories and techniques of dendrochronology. We collected increment cores and cross-section disks from conifers in a subalpine meadow to determine their dates of establishment. We compared these establishment dates with climatic and environmental variables to assess potential drivers of encroachment. Our results show that the establishment of conifer seedlings occurred in distinct pulses over the twentieth century coinciding with periods of low summer snowfall. We found that seedling establishment rates were much higher on locally convex micro-topographic settings and in areas with a dense cover of woody shrubs. The spatiotemporal patterns of seedling establishment we observed appear to be the result of the complicated and highly scale-dependent interplay between climatic fluctuations and both biotic and abiotic microsite conditions. While our results should be considered a preliminary analysis, they reveal a compelling story of the spatiotemporal patterns of conifer encroachment and suggest potential causal mechanisms that warrant further investigation.

Habitat selection and use by sympatric, translocated greater sage‐grouse and Columbian sharp‐tailed grouse

ABSTRACTGreater sage‐grouse (Centrocercus urophasianus) and Columbian sharp‐tailed grouse (Tympanuchus phasianellus columbianus) have declined substantially in Washington, USA, primarily because native shrub‐steppe has been converted to agriculture. In response, state and federal agencies have acquired and restored habitat, and augmented and reintroduced grouse to suitable areas. We examined how sympatric, translocated sage‐grouse and sharp‐tailed grouse used space and selected habitats within their spring–summer home ranges and at nest sites within remnant shrub‐steppe surrounded by a matrix of cropland in eastern Washington. Because their life‐history requirements differ, we expected extensive habitat partitioning between species. Using radiolocations of ≥43 birds of each species, we found that sage‐grouse had larger spring–summer home ranges than sharp‐tailed grouse, and the composite of home ranges for sharp‐tailed grouse fell almost completely within the composite of home ranges for sage‐grouse. By creating resource utilization function models using radiolocations of ≥53 birds of each species, we found that areas of highest predicted intensity of use for both species overlapped by >50%, even at the top 5% quantile. Both species used restored fields and areas farther from trees and roads or distribution lines more intensely. Sage‐grouse used less rugged areas more intensely, and both species used 3 levels of shrub cover equally. To compare selection of nest sites relative to available sites for nesting in both species, we created resource selection function models for ≥30 birds of each species and found that sage‐grouse selected areas farther from distribution lines, whereas sharp‐tailed grouse selected restored fields. When we examined vegetation characteristics used by female sage‐grouse and sharp‐tailed grouse at nest sites using a case‐control, use versus non‐use design for ≥26 birds of each species, we found sage‐grouse used areas with greater shrub cover, lower annual forb cover, and taller perennial grasses, whereas sharp‐tailed grouse used areas with greater perennial grass cover and taller perennial grasses and forbs. When we compared habitat features measured at nest sites between species, we found sage‐grouse used areas with greater moderate and dense shrub cover, lower sparse shrub cover, less restored fields, higher patch diversity, and areas farther from distribution lines than sharp‐tailed grouse. These differences resulted in only 38% overlap of areas within the top quartile of relative selection values for nest sites by the 2 species, and <10% at the top 5% quantile. Because many western states are highly fragmented by cropland, understanding how populations of species with different life‐history characteristics, such as sage‐grouse and sharp‐tailed grouse, coexist within remaining tracts of shrub‐steppe at different spatial scales is important for effectively conserving and managing shrub‐steppe communities. © 2015 The Wildlife Society.

Estimating the Effects of Habitat and Biological Interactions in an Avian Community.

We used repeated sightings of individual birds encountered in community-level surveys to investigate the relative roles of habitat and biological interactions in determining the distribution and abundance of each species. To analyze these data, we developed a multispecies N-mixture model that allowed estimation of both positive and negative correlations between abundances of different species while also estimating the effects of habitat and the effects of errors in detection of each species. Using a combination of single- and multispecies N-mixture modeling, we examined for each species whether our measures of habitat were sufficient to account for the variation in encounter histories of individual birds or whether other habitat variables or interactions with other species needed to be considered. In the community that we studied, habitat appeared to be more influential than biological interactions in determining the distribution and abundance of most avian species. Our results lend support to the hypothesis that abundances of forest specialists are negatively affected by forest fragmentation. Our results also suggest that many species were associated with particular types of vegetation as measured by structural attributes of the forests. The abundances of 6 of the 73 species observed in our study were strongly correlated. These species included large birds (American Crow (Corvus brachyrhynchos) and Red-winged Blackbird (Agelaius phoeniceus)) that forage on the ground in open habitats and small birds (Red-eyed Vireo (Vireo olivaceus), House Wren (Troglodytes aedon), Hooded Warbler (Setophaga citrina), and Prairie Warbler (Setophaga discolor)) that are associated with dense shrub cover. Species abundances were positively correlated within each size group and negatively correlated between groups. Except for the American Crow, which preys on eggs and nestlings of small song birds, none of the other 5 species is known to display direct interactions, so we suspect that the correlations may have been associated with species-specific responses to habitat components not adequately measured by our covariates.

Contemporary and historic population structure of Abies spectabilis at treeline in Barun valley, eastern Nepal Himalaya

Treeline ecotone dynamics of Abies spectabilis (D. Don) Mirb. in the Barun valley, Makalu Barun National Park, eastern Nepal Himalaya were studied by establishing seven plots (20 m × variable length) from the forestline to the tree species limit: three plots on the south- and north-facing slopes each (S1–S3, N1–N3), and one plot on the east-facing slope (E) in the relatively undisturbed forests. A dendroecological method was used to study treeline advance rate and recruitment pattern. In all the plots, most trees established in the early 20th century, and establishment in the second half of the 20th century was confined to the forestline area. Treeline position has not advanced substantially in the Barun valley, with only 22 m average elevational shift in the last 130 years, and with average current shifting rate of 14 cm/yr. Moreover, no significant relationship was found between tree age and elevation on the south-, north-, and east-facing slopes. The number of seedlings and saplings in near the treeline area was negligible compared to that near the forestline area. Therefore, A. spectabilis treeline response to the temperature change was slow, despite the increasing temperature trend in the region. Beside the temperature change, factors such as high inter-annual variability in temperature, dense shrub cover, and local topography also play an important role in treeline advance and controlling recruitment pattern above the treeline.

Ecological factors influencing the winter abundance of mammals in temperate forest

We examined the ecological factors influencing winter abundance of mammals in the natural deciduous forest and the Japanese larch, Larix leptolepis, plantation in Mount Maehwa, Hongcheon, South Korea. We counted the tracks of five mammal species — the Korean hare, Lepus coreanus; the raccoon dog, Nyctereutes procyonoides; the Siberian weasel, Mustela sibirica; the water deer, Hydropotes inermis and the wild boar, Sus scrofa — in the snow from November 2013 to February 2014. We showed that the mean basal area, canopy cover and shrub cover were significantly higher in the Japanese larch plantation than in the natural deciduous forest. The winter abundances of Korean hares, raccoon dogs and water deer were higher in the Japanese larch plantation than in the natural deciduous forest. The results of stepwise analysis revealed that the winter abundances of four species were significantly correlated with ≥ 1 of the habitat variables. The winter abundances of Korean hares, water deer and wild boars were significantly correlated with shrub cover. The winter abundances of Korean hares, raccoon dogs and wild boars were significantly correlated with fallen logs; and the winter abundance of water deer was significantly correlated with canopy cover. For all of the investigated species, the preferred winter habitat was the Japanese larch plantation, with dense shrub cover and high number of fallen logs. Our results indicate that for planning conservation and forest management strategies for mammal species, the preferred forest habitat variables must be taken into consideration.