Managing for multiple species: greater sage-grouse and sagebrush songbirds

Human activity has altered 33–50% of Earth's surface, including temperate grasslands and sagebrush rangelands, resulting in a loss of biodiversity. By promoting habitat for sensitive or wide-ranging species, less exigent species may be protected in an umbrella effect. The greater sage-grouse (Centrocercus urophasianus; sage-grouse) has been proposed as an umbrella for other sagebrush-obligate species because it has an extensive range that overlaps with many other species, it is sensitive to anthropogenic activity, it requires resources over large landscapes, and its habitat needs are known. The efficacy of the umbrella concept, however, is often assumed and rarely tested. Therefore, we surveyed sage-grouse pellet occurrence and sagebrush-associated songbird abundance in northwest Colorado, USA, to determine the amount of habitat overlap between sage-grouse and 4 songbirds (Brewer's sparrow [Spizella breweri], sage thrasher [Oreoscoptes montanus], sagebrush sparrow [Artemisiospiza nevadensis]), and green-tailed towhee [Pipilo chlorurus]). During May and June 2013–2015, we conducted standard point count breeding surveys for songbirds and counted sage-grouse pellets within 300 10-m radius plots. We modeled songbird abundance and sage-grouse pellet occurrence with multi-scaled environmental features, such as sagebrush cover and bare ground. To evaluate sage-grouse as an umbrella for sagebrush-associated passerines, we determined the correlation between probability of sage-grouse pellet occurrence and model-predicted songbird densities per sampling plot. We then classified the sage-grouse probability of occurrence as high (probability >0.5) and low (probability ≤0.5) and mapped model-predicted surfaces for each species in our study area. We determined average songbird density in areas of high and low probability of sage-grouse occurrence. Sagebrush cover at intermediate scales was an important predictor for all species, and ground cover was important for all species except sage thrashers. Areas with a higher probability of sage-grouse occurrence also contained higher densities of Brewer's sparrows, green-tailed towhees, and sage thrashers, but predicted sagebrush sparrow densities were lower in these areas. In northwest Colorado, sage-grouse may be an effective umbrella for Brewer's sparrows, green-tailed towhees, and sage thrashers, but sage-grouse habitat does not appear to capture areas that support high sagebrush sparrow densities. A multi-species focus may be the best management and conservation strategy for several species of concern, especially those with conflicting habitat requirements. © The Wildlife Society, 2019     

Greater Sage-Grouse Nesting Habitat: The Importance of Managing at Multiple Scales

Abstract: Considering habitat selection at multiple scales is essential to fully understand habitat requirements and management needs for wildlife species of concern. We used a hierarchical information-theoretic approach and variance decomposition techniques to analyze habitat selection using local-scale habitat variables measured in the field and landscape-scale variables derived with a Geographic Information System (GIS) for nesting greater sage-grouse (Centrocercus urophasianus) in the Powder River Basin (PRB), Montana and Wyoming, USA, 2003–2007. We investigated relationships between habitat features that can and cannot be mapped in a GIS to provide insights into interpretation of landscape-scale—only GIS models. We produced models of habitat selection at both local and landscape scales and across scales, yet multiscale models had overwhelming statistical and biological support. Variance decomposition showed that local-scale measures explained the most pure variation (50%) in sage-grouse nesting-habitat selection. Landscape-scale features explained 20% of pure variation and shared 30% with local-scale features. Both local- and landscape-scale habitat features are important in sage-grouse nesting-habitat selection because each scale explained both pure and shared variation. Our landscape-scale model was accurate in predicting priority landscapes where sage-grouse nests would occur and is, therefore, useful in providing landscape context for management decisions. It accurately predicted locations of independent sage-grouse nests (validation R² = 0.99) and showed good discriminatory ability with >90% of nests located within only 40% of the study area. Our landscape-scale model also accurately predicted independent lek locations. We estimated twice the amount of predicted nesting habitat within 3 km of leks compared to random locations in the PRB. Likewise we estimated 1.8 times more predicted nesting habitat within 10 km of leks compared to random locations. These results support predictions of the hotspot theory of lek placement. Local-scale habitat variables that cannot currently be mapped in a GIS strongly influence sage-grouse nest-site selection, but only within priority nesting habitats defined at the landscape scale. Our results indicate that habitat treatments for nesting sage-grouse applied in areas with an unsuitable landscape context are unlikely to achieve desired conservation results.     

Anthropogenic and Natural Disturbance Differentially Affect Sagebrush Bird Habitat Use

North American sagebrush (Artemisia spp.)-obligate birds are experiencing steep population declines due in part to increased disturbance, mainly human-caused, across their range. At the eastern edge of the sagebrush steppe, this issue may potentially be exacerbated because of natural disturbance by black-tailed prairie dogs (Cynomys ludovicianus). Our goal was to compare local and landscape models of habitat use by greater sage-grouse (Centrocercus urophasianus), Brewer's sparrow (Spizella breweri), and sage thrasher (Oreoscoptes montanus) with models including effects of natural (i.e., prairie dog) and anthropogenic disturbance. We used a combination of field data collection, and state and national datasets for the Thunder Basin National Grassland, eastern Wyoming, USA, to understand the factors that influence lek attendance by sage-grouse and habitat use by 2 passerines in this system. For all 3 species, models including big sagebrush (Artemisia tridentata) cover at local and landscape scales were the most competitive among univariate models, supporting the paradigm that sagebrush is key for these species. Models including anthropogenic disturbance (well density, road density) explained more variation than models of prairie dog disturbance alone for 2 of the 3 species, but long-term disturbance by prairie dogs did reduce abundance of Brewer's sparrows. Although long-term prairie dog disturbance has the potential to reduce sagebrush cover for sagebrush-obligate birds, such events are likely rare because outbreaks of plague (Yersina pestis) and lethal control on borders with private land reduce prairie dog disturbance. Conversely, anthropogenic disturbance is slated to increase in this system, suggesting potentially accelerated declines for sagebrush birds into the future. © 2020 The Wildlife Society.     

Greater sage-grouse winter habitat use on the eastern edge of their range

Greater sage-grouse (Centrocercus urophasianus) at the western edge of the Dakotas occur in the transition zone between sagebrush and grassland communities. These mixed sagebrush (Artemisia sp.) and grasslands differ from those habitats that comprise the central portions of the sage-grouse range; yet, no information is available on winter habitat selection within this region of their distribution. We evaluated factors influencing greater sage-grouse winter habitat use in North Dakota during 2005–2006 and 2006–2007 and in South Dakota during 2006–2007 and 2007–2008. We captured and radio-marked 97 breeding-age females and 54 breeding-age males from 2005 to 2007 and quantified habitat selection for 98 of these birds that were alive during winter. We collected habitat measurements at 340 (177 ND, 163 SD) sage-grouse use sites and 680 random (340 each at 250 m and 500 m from locations) dependent sites. Use sites differed from random sites with greater percent sagebrush cover (14.75% use vs. 7.29% random; P < 0.001), percent total vegetation cover (36.76% use vs. 32.96% random; P ≤ 0.001), and sagebrush density (2.12 plants/m² use vs. 0.94 plants/m² random; P ≤ 0.001), but lesser percent grass cover (11.76% use vs. 16.01% random; P ≤ 0.001) and litter cover (4.34% use vs. 5.55% random; P = 0.001) and lower sagebrush height (20.02 cm use vs. 21.35 cm random; P = 0.13) and grass height (21.47 cm use vs. 23.21 cm random; P = 0.15). We used conditional logistic regression to estimate winter habitat selection by sage-grouse on continuous scales. The model sagebrush cover + sagebrush height + sagebrush cover × sagebrush height ( = 0.60) was the most supported of the 13 models we considered, indicating that percent sagebrush cover strongly influenced selection. Logistic odds ratios indicated that the probability of selection by sage-grouse increased by 1.867 for every 1% increase in sagebrush cover (95% CI = 1.627–2.141) and by 1.041 for every 1 cm increase in sagebrush height (95% CI = 1.002–1.082). The interaction between percent sagebrush canopy cover and sagebrush height (β = −0.01, SE ≤ 0.01; odds ratio = 0.987 [95% CI = 0.983–0.992]) also was significant. Management could focus on avoiding additional loss of sagebrush habitat, identifying areas of critical winter habitat, and implementing management actions based on causal mechanisms (e.g., soil moisture, precipitation) that affect sagebrush community structure in this region. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.     

Greater Sage-Grouse Winter Habitat Selection and Energy Development

Abstract Recent energy development has resulted in rapid and large-scale changes to western shrub-steppe ecosystems without a complete understanding of its potential impacts on wildlife populations. We modeled winter habitat use by female greater sage-grouse (Centrocercus urophasianus) in the Powder River Basin (PRB) of Wyoming and Montana, USA, to 1) identify landscape features that influenced sage-grouse habitat selection, 2) assess the scale at which selection occurred, 3) spatially depict winter habitat quality in a Geographic Information System, and 4) assess the effect of coal-bed natural gas (CBNG) development on winter habitat selection. We developed a model of winter habitat selection based on 435 aerial relocations of 200 radiomarked female sage-grouse obtained during the winters of 2005 and 2006. Percent sagebrush (Artemisia spp.) cover on the landscape was an important predictor of use by sage-grouse in winter. The strength of habitat selection between sage-grouse and sagebrush was strongest at a 4-km² scale. Sage-grouse avoided coniferous habitats at a 0.65-km² scale and riparian areas at a 4-km² scale. A roughness index showed that sage-grouse selected gentle topography in winter. After controlling for vegetation and topography, the addition of a variable that quantified the density of CBNG wells within 4 km² improved model fit by 6.66 Akaike's Information Criterion points (Akaike wt = 0.965). The odds ratio for each additional well in a 4-km² area (0.877; 95% CI = 0.834- 0.923) indicated that sage-grouse avoid CBNG development in otherwise suitable winter habitat. Sage-grouse were 1.3 times more likely to occupy sagebrush habitats that lacked CBNG wells within a 4-km² area, compared to those that had the maximum density of 12.3 wells per 4 km² allowed on federal lands. We validated the model with 74 locations from 74 radiomarked individuals obtained during the winters of 2004 and 2007. This winter habitat model based on vegetation, topography, and CBNG avoidance was highly predictive (validation R² = 0.984). Our spatially explicit model can be used to identify areas that provide the best remaining habitat for wintering sage-grouse in the PRB to mitigate impacts of energy development.     

Scales and costs of habitat selection in heterogeneous landscapes

Summary Two scales of habitat selection are likely to influence patterns of animal density in heterogeneous landscapes. At one scale, habitat selection is determined by the differential use of foraging locations within a home range. At a larger scale, habitat selection is determined by dispersal and the ability to relocate the home range. The limits of both scales must be known for accurate assessments of habitat selection and its role in effecting spatial patterns in abundance. Isodars, which specify the relationships between population density in two habitats such that the expected reproductive success of an individual is the same in both, allow us to distinguish the two scales of habitat selection because each scale has different costs. In a two-habitat environment, the cost of rejecting one of the habitats within a home range can be expressed as a devaluation of the other, because, for example, fine-grained foragers must travel through both. At the dispersal scale, the cost of accepting a new home range in a different habitat has the opposite effect of inflating the value of the original habitat to compensate for lost evolutionary potential associated with relocating the home range. These costs produce isodars at the foraging scale with a lower intercept and slope than those at the dispersal scale.Empirical data on deer mice occupying prairie and badland habitats in southern Alberta confirm the ability of isodar analysis to differentiate between foraging and dispersal scales. The data suggest a foraging range of approximately 60 m, and an effective dispersal distance near 140 m. The relatively short dispersal distance implies that recent theories may have over-emphasized the role of habitat selection on local population dynamics. But the exchange of individuals between habitats sharing irregular borders may be substantial. Dispersal distance may thus give a false impression of the inability of habitat selection to help regulate population density.     

Energy development affects populations of sagebrush songbirds in Wyoming

Oil and natural gas development in the Intermountain West region of North America has expanded over the last 2 decades, primarily within sagebrush dominated landscapes. Although the effects of energy development on high-profile game species such as the greater sage-grouse (Centrocercus urophasianus) have been documented, studies examining responses of non-game birds are lacking. Simultaneously, many songbirds that breed within sagebrush steppe habitats have shown range-wide population declines that are likely due to widespread habitat loss and alteration. We evaluated songbird abundance and species richness across gradients of oil and natural gas development intensity, as indexed by well density, at 3 energy fields (2 natural gas and 1 oil) in the Upper Green River Basin, Wyoming, USA during 2008–2009. While simultaneously accounting for important habitat attributes, increased well density was associated with significant decreases in Brewer's sparrow (Spizella breweri) and sage sparrow (Amphispiza belli) abundance, particularly in the Jonah natural gas field. Vesper sparrows (Pooecetes gramineus) were also negatively influenced by increased well density. Horned larks (Eremophila alpestris) increased with well density in the Pinedale Anticline natural gas field, and sage thrashers (Oreoscoptes montanus) showed no response to energy development. Species richness was not significantly affected by well density. Results suggest that regional declines of some songbird species, especially sagebrush-obligates, may be exacerbated by increased energy development. Understanding the specific mechanisms underlying responses to energy development is an important next step and will aid land managers in the development of effective mitigation and management strategies for the maintenance of stable bird communities in sagebrush habitat. © 2011 The Wildlife Society.     

Genetic Analysis of Invasive Plant Populations at Different Spatial Scales

Measuring genetic diversity requires selection of a spatial scale of analysis. Different levels of genetic structuring are revealed at different spatial scales, however, and the relative importance of factors driving genetic structuring varies along the spatial scale continuum. Unequal gene flow is a major factor determining genetic structure in plant populations at the local level, while the effect of selection imposed by environmental heterogeneity increases with the spatial scale of analysis. At a continental and global scale genetic structure of invasive plant populations is significantly affected by founder effect and propagule transport via human vectors. Although genetic analysis at one spatial scale provides only partial information about the invasion process, little published research reports such data for the same species at multiple scales. A multi-faceted approach to investigating the genetic structure of invasive plant species that incorporates sampling at different spatial and temporal scales would provide a more complete picture of the role of genetic forces in invasion.     

Eastern Hog-Nosed Snake Habitat Selection at Multiple Spatial Scales in Ontario,Canada

Habitat loss is the greatest contributor to the decline of species globally. To prioritize protection of imperiled species, it is important to examine habitat use at multiple spatial scales because the availability of different resources and habitat features is scale dependent. We conducted a radio-telemetry study in the Long Point region of Ontario, Canada, in 2009 and 2010 to examine habitat selection at multiple spatial scales by eastern hog-nosed snakes (Heterodon platirhinos), a species at risk in Canada. We documented the habitat composition of home ranges compared to the surrounding landscape, the selection of locations within home ranges based on classified satellite imagery, and the use of microhabitat features based on site characterization in the field. At the scale of the home ranges, hog-nosed snakes avoided areas of agriculture and selected sand barrens. Within home ranges, hog-nosed snakes selectively used areas altered by humans (e.g., residential sites, openings in tree plantations). Microhabitats used by hog-nosed snakes had more woody debris, logs, and lower vegetative coverage than adjoining random sites. Because hog-nosed snakes prefer open areas and require sandy soils for nesting, management efforts should focus on the conservation and maintenance of sand barrens and patches of early successional forest. © 2021 The Wildlife Society.     

物种灭绝对不同时间尺度栖息地毁坏响应的空间模拟

人类活动所引起的栖息地毁坏已成为当前物种多样性丧失的最主要的原因之一。空间显含模型相对于空间隐含模型来说,更加接近于现实,因此,通过元胞自动机,模拟了物种多样性对万年、千年、百年时间尺度人类活动所引起的栖息地毁坏的响应。研究结果表明：万年时间尺度上,物种是由强到弱的灭绝;而在千年时间尺度上,物种灭绝的序受集合种群结构的影响较大;在百年时间尺度上。物种由于栖息地毁坏过于剧烈和迅速,来不及作出响应。在栖息地完全毁坏时集体灭绝。因此,物种灭绝序不只是受竞争-侵占均衡机制的影响,还受不同时间尺度（不同速率）栖息地毁坏的影响。以及集合种群结构的影响。     

Influence of Vegetation on Bat Use of Riparian Areas at Multiple Spatial Scales

ABSTRACT Research on habitat use by bats typically occurs at a single fine spatial scale, despite recent work demonstrating the importance of considering multiple spatial scales when investigating vertebrate habitat selection. We assessed bat use of 118 stream reaches located throughout the Oregon Coast Range, USA, and measured vegetation characteristics at 3 spatial scales surrounding each of these locations. We used an information-theoretic approach to determine vegetation characteristics most closely related to bat activity and a multilevel modeling approach to evaluate variation in bat activity at different spatial scales. Characteristics of vegetation at the finest spatial scale explained more variation in bat activity than did characteristics of vegetation at broader spatial scales, suggesting that fine-scale anthropogenic or natural disturbance events that alter cover of shrubs or trees in riparian areas are likely to influence bat habitat use. The influence of vegetation on activity varied by species of bat and appeared to operate more strongly through constraints imposed by vegetation architecture than through influences on abundance of insect prey. This diversity of responses to vegetation characteristics among bat species suggests that the best strategy for biodiversity conservation over broad spatial scales is maintenance or creation of a diversity of riparian vegetation conditions. We recommend that land managers planning to manipulate riparian vegetation strive to create diversity in shrub coverage, canopy coverage, and open space above the stream channel to promote foraging habitat for all species.     

Predicting greater sage‐grouse habitat selection at the southern periphery of their range

Mapping suitable habitat is an important process in wildlife conservation planning. Species distribution reflects habitat selection processes occurring across multiple spatio‐temporal scales. Because habitat selection may be driven by different factors at different scales, conservation planners require information at the scale of the intervention to plan effective management actions. Previous research has described habitat selection processes shaping the distribution of greater sage‐grouse (Centrocercus urophasianus; sage‐grouse) at the range‐wide scale. Finer‐scale information for applications within jurisdictional units inside the species range is lacking, yet necessary, because state wildlife agencies are the management authority for sage‐grouse in the United States. We quantified seasonal second‐order habitat selection for sage‐grouse across the state of Utah to produce spatio‐temporal predictions of their distribution at the southern periphery of the species range. We used location data obtained from sage‐grouse marked with very‐high‐frequency radio‐transmitters and lek location data collected between 1998 and 2013 to quantify species habitat selection in relation to a suite of topographic, edaphic, climatic, and anthropogenic variables using random forest algorithms. Sage‐grouse selected for greater sagebrush (Artemisia spp.) cover, higher elevations, and gentler slopes and avoided lower precipitations and higher temperatures. The strength of responses to habitat variables varied across seasons. Anthropogenic variables previously reported as affecting their range‐wide distribution (i.e., roads, powerlines, communication towers, and agricultural development) were not ranked as top predictors at our focal scale. Other than strong selection for sagebrush cover, the responses we observed differed from what has been reported at the range‐wide scale. These differences likely reflect the unique climatic, geographic, and topographic context found in the southern peripheral area of the species distribution compared to range‐wide environmental gradients. Our results highlight the importance of considering appropriateness of scale when planning conservation actions for wide‐ranging species.     

山西五鹿山褐马鸡不同季节的空间分布与栖息地选择研究

1997～1998年在山西省五鹿山自然保护区内对世界珍禽褐马鸡(Crossoptilon mantchuricum)越冬期与繁殖期的空间分布模式及其变化规律进行了研究,同时探讨了种群空间分布模式与栖息地结构特征之间的关系。经Pois—son函数和χ^2检验,发现褐马鸡在越冬期和繁殖期均为聚集分布,但越冬期的聚集程度更为明显。通过对栖息地可利用率与实际利用率的比较,发现褐马鸡在越冬期与繁殖期对栖息地的利用存在显著性差异：越冬期褐马鸡对阔叶林具有明显的负选择性;进入繁殖期后,褐马鸡对落叶阔叶林和灌丛的利用率显著增加,而对针叶林和针阔混交林的利用率有所减少。对两个时期的栖息地样方进行判别分析,发现草本植物数量、草本植物平均高度、乔木胸径、乔木高度是影响褐马鸡越冬期与繁殖期栖息地选择的主要因子。研究结果表明,褐马鸡种群的空间分布模式及其变化,与栖息地结构以及空间资源分布的季节性变化有关。在越冬期,由于温度、降雪等气候因素的影响,草本植物都已枯萎,落叶阔叶林的郁闭度较低,隐蔽条件较差,褐马鸡活动的区域范围受到一定的限制,此时褐马鸡常常在郁闭度较高的针叶林或针阔混交林中,并聚集形成较大的群体,共同取食,聚集分布的程度较高;进入繁殖期后,随着落叶阔叶林郁闭度增大以及林下、灌草丛中草本植物种类和数量的增多,褐马鸡群体逐渐变小,多以配偶对的形式活动,空间聚集程度降低。但由于褐马鸡对栖息地具有严格的选择性,许多配偶对主要集中在质量较好的区域内占区和营巢,因此在大尺度上褐马鸡种群的空间分布仍为聚集型分布。     

蓝冠噪鹛繁殖期生境选择特征分析

2013年至2015年每年4—7月,在江西婺源境内对蓝冠噪鹛繁殖小群进行调查。观察并测量其繁殖地斑块海拔,距山地、水源及干扰源的距离,计算斑块面积、周长及形状指数,并在每个繁殖斑块的4个方向5km以外选取同样植被类型的对照斑块,比较繁殖斑块与对照斑块在以上7个因子的差异。结果表明繁殖斑块海拔,距山地距离和距干扰距离显著小于对照斑块。说明在斑块尺度上,蓝冠噪鹛繁殖期倾向于选择低海拔阔叶林,且在离山地更近的村庄附近繁殖,这可能与食物丰富和天敌较少有关。在微生境尺度,选择繁殖点B在巢区及同一片阔叶林中无噪鹛筑巢的对照区进行10个生态因子的测量,并用资源选择函数以及Vanderploeg和Scavia选择系数进行分析。资源选择函数结果表明草本密度、草本高度在微生境尺度对蓝冠噪鹛生境选择贡献最大;而Vanderploeg和Scavia选择系数结果表明蓝冠噪鹛喜在胸径较粗(40—80cm)的朴树、枫杨和枫香3种树上筑巢,筑巢偏好树高20m以上及草本盖度较高(60%—90%)的生境。综合两种分析结果,在微生境尺度蓝冠噪鹛对筑巢树种及高度具有选择性,对巢区隐蔽性有所要求,巢下草本情况可以反映昆虫等食物资源状况,说明蓝冠噪鹛繁殖期偏好在食物相对丰富的区域筑巢。     

完达山东部林区生境特征对东北林蛙产卵的影响

在研究人员逐渐将研究的焦点集中在栖息生境破碎化和生境丧失对在池塘繁育的两栖动物的影响方面。至今,许多研究已经评估了在多个空间尺度下生境因子对两栖类动物繁育池选择的影响。由于在1个繁育池内1只林蛙只产1团卵,因此利用繁育池内蛙卵团数与生境因子之间存在的内在联系建立生境选择函数模型,探究林蛙繁育期不同生境因子对东北林蛙种群大小的影响。从2012年到2014年5月初至7月末的东北林蛙繁育期,在完达山东部五泡林场,共调查了105个水池,93.33%的池塘中发现了林蛙卵团。在繁育池微生境尺度水平,广义可加模型分析表明,繁育池面积对东北林蛙卵团数产生积极影响,对林蛙卵团数的贡献为0.17;但林木郁闭度和繁育池水表面杂物盖度对林蛙卵团数产生负面影响,对林蛙卵团数贡献分别为-0.30和-0.43。在繁育池周围5km景观尺度水平,森林面积对蛙卵数产生积极影响,对GAM预测模型的贡献为17.99;公路干扰对蛙卵团数产生负面影响,随着距公路距离增加,林蛙卵团数增加,对GAM预测模型的贡献为1.40。研究结果表明,虽然在繁育池微生境尺度水平预测模型包含的变量较景观尺度水平预测模型包含的变量多,但两个模型对于预测林蛙个体产卵团数均有效。因此,可以认为,保护林蛙种群生存和繁育,需要优先保护面积为4—150 m~2,池内水表面有一定杂物覆盖(0—14%),林木郁闭度较小(约10%),森林覆盖率高,距公路较远的区域。     

Fire,landscape change and models of small mammal habitat suitability at multiple spatial scales

Fire is an important process in many ecosystems, but inappropriate fire regimes can adversely affect biodiversity. We identified a naturally flammable heathy woodland ecosystem where the use of planned fire had increased the extent of older vegetation, and quantified the abundance of two small native mammals in this landscape (silky mouse Pseudomys apodemoides and heath rat P. shortridgei). We defined four time‐since‐fire (TSF) categories representing a 2‐ to 55‐year post‐fire sequence and, on the basis of a habitat accommodation model, predicted that both species would select younger age‐classes over older ones. We also predicted that (i) much of the variance in vegetation structure would remain unexplained by TSF and (ii) statistical models of mammal abundance and occupancy including structural variables as predictors would be better than models including TSF. Pseudomys apodemoides selected 17‐ to 23‐year‐old sites, while there was no evidence that P. shortridgei selected a particular TSF category, findings that were inconsistent with our predictions. In line with our predictions, relatively large portions of the variance in vegetation structure remained unexplained by TSF (adjustedr² for four structural variables: 0.24, 0.29, 0.35 and 0.57), and in three of four cases there was strong evidence that statistical models of mammal abundance and occupancy including structural variables were better than those including TSF. At the site scale (hectares), P. shortridgei abundance was positively related to the cover of dead material at the base of Xanthorrhoea plants and at the trap scale (metres), the trapability of both species was significantly related to vegetation volume at 0–20 cm. Our findings suggest that TSF may not be a good proxy for either vegetation structure or species abundance/occupancy.     

Spatial scale dependence of the species diversityin Tianmu Mountain and its relationship with spatial patterns by using multifractal analysis

This study took the Tianmu Mountain National Natural Preservation Area in western Zhejiang Province as an example 1) to quantify the species diversity with selected species indices including Shannon-Wiener index (H), Margalef index (K) and Evenness index (E) at different spatial scales, 2) to analyze the spatial distribution patterns of the species diversity by multifractal parameters such as the singularity index α, its fractal dimension f(α), the f(α)–α spectrum range (SR) and its symmetry (Dist) using the multifractal theory, and 3) to determine their relationships. Results of nonlinear regression analysis with power functions showed that increasing spatial scale resulted in increasing H but decreasing E and K, indicating that the scale dependence of species diversity existed. By using the multifractal method, it was indicated that species spatial distribution had multifractal features. Moreover, strong linear relationships of the diversity indices H, E and K with α_min and clear nonlinear associations of the diversity indices H, E and K with power functions for SR and Dist were found. Since interactions of the species diversity and the spatial characteristics are very complex, the above mentioned relationships need further validation along with precise explanations of any correlations among their ecological processes.     

Spatial scale dependence of the species diversityin Tianmu Mountain and its relationship with spatial patterns by using multifractal analysis

This study took the Tianmu Mountain National Natural Preservation Area in western Zhejiang Province as an example 1) to quantify the species diversity with selected species indices including Shannon-Wiener index (H), Margalef index (K) and Evenness index (E) at different spatial scales, 2) to analyze the spatial distribution patterns of the species diversity by multifractal parameters such as the singularity index α, its fractal dimension f(α), the f(α)–α spectrum range (SR) and its symmetry (Dist) using the multifractal theory, and 3) to determine their relationships. Results of nonlinear regression analysis with power functions showed that increasing spatial scale resulted in increasing H but decreasing E and K, indicating that the scale dependence of species diversity existed. By using the multifractal method, it was indicated that species spatial distribution had multifractal features. Moreover, strong linear relationships of the diversity indices H, E and K with α_min and clear nonlinear associations of the diversity indices H, E and K with power functions for SR and Dist were found. Since interactions of the species diversity and the spatial characteristics are very complex, the above mentioned relationships need further validation along with precise explanations of any correlations among their ecological processes.     

吉林西部草原地区蚂蚁种类及分布

在吉林西部草原地区蚂蚁是大型土壤动物的优势类群,数量巨大,但种类少,仅发现3亚科9属14种。放牧场、撂荒地、农田、人工林、乡间土路、院落6种生境中分布最多的蚂蚁是红林蚁和铺道蚁,撂荒地和人工林的蚂蚁种类和巢口密度最大。在割草场分布的蚂蚁主要是玉米毛蚁、黄墩蚁和铺道蚁,它们均修建明显的地上蚁丘,蚁丘呈环带状分布,即主要分布在草地与碱斑的交界处,并且从草场边缘向中心,蚁丘的数量逐渐减少。利用拥挤度指数对蚁丘的分布格局进行分析,表明蚁丘呈聚集分布,并对可能影响蚁巢分布的因素进行了探讨。