Simple predictions of instream habitat model outputs for fish habitat guilds in large streams

1. In the context of a generalised modification of hydraulic conditions in medium to large streams, modelling the impacts of stream regulation on fish communities in multiple streams is an important challenge for basic and applied freshwater ecology. Conventional instream habitat models such as PHABSIM link a hydraulic model with preference curves for various species to estimate habitat value changes with discharge in stream reaches. Despite world‐wide applications, they have been scarcely used in multiple sites with multiple species. 2. We assigned 21 size classes of European fish species to four habitat guilds (cluster analysis grouping size classes with comparable microhabitat preference curves). Then, we ran a conventional instream habitat model on 28 French stream reaches belonging to the `barbel zone', to estimate habitat values versus discharge curves for the 21 size classes. We summarised the outputs as mean habitat values for guilds, and tested if they were predictable from average characteristics of reaches (discharge, depth, width, particle size). 3. As was obtained elsewhere for populations, habitat values for guilds were strongly related to average, dimensionless characteristics of reaches. The Reynolds number of reaches, equivalent to a discharge per width unit, reflected most of the discharge‐dependent changes in habitat values (within reaches). In particular, habitat values of species preferring bank (respectively midstream) microhabitats decreased (respectively increased) with increasing Reynolds number. The Froude number at median discharge was the major predictor of reach‐dependent but discharge‐independent variations in habitat values. Habitat values of species preferring riffle versus pool or bank microhabitats were higher in reaches with high Froude numbers. These relationships were consistent with existing knowledge on the different species. 4. Such results suggest that the input variables required to estimate habitat values for fish communities can be greatly simplified, as illustrated by a general estimation of the sensitivity of species preferring midstream habitats to discharge changes in any reach. Cost‐efficient alternatives to conventional instream habitat models should facilitate their validation in multiple sites, a point that remains critical in instream habitat modelling of fish communities.     

Can settlement in natal-like habitat explain maladaptive habitat selection?

The study of habitat selection has long been influenced by the ideal free model, which maintains that young adults settle in habitat according to its inherent quality and the density of conspecifics within it. The model has gained support in recent years from the finding that conspecifics produce cues inadvertently that help prebreeders locate good habitat. Yet abundant evidence shows that animals often fail to occupy habitats that ecologists have identified as those of highest quality, leading to the conclusion that young animals settle on breeding spaces by means not widely understood. Here, we report that a phenomenon virtually unknown in nature, natal habitat preference induction (NHPI), is a strong predictor of territory settlement in both male and female common loons (Gavia immer). NHPI causes young animals to settle on natal-like breeding spaces, but not necessarily those that maximize reproductive success. If widespread, NHPI might explain apparently maladaptive habitat settlement.     

生境破碎化对动物种群存活的影响

生境破碎是生物多样性下降的主要原因之一。通常以岛屿生物地理学、异质种群生物学和景观生态学的理论来解释不同空间尺度中生境破碎化的生态学效应。生境破碎化引起面积效应、隔离效应和边缘效应。这些效应通过影响动物种群的绝灭阈值、分布和多度、种间关系以及生态系统过程,最终影响动物种群的存活。野外研究表明,破碎化对动物的影响,因物种、生境类型和地理区域不同而有所变化,因此,预测物种在破碎生境中的存活比较困难。研究热点集中于：确定生境面积损失和生境斑块的空间格局对破碎景观中物种绝灭的相对影响,破碎景观中物种的适宜生境比例和绝灭阈值,异质种群动态以及生态系统的生态过程。随着3S技术的发展,生境破碎化模型趋于复杂,而发展有效的模型和验证模型将成为一项富有挑战性的任务。     

Independent effects of habitat loss,habitat fragmentation and structural connectivity on forest‐dependent birds

Aim Habitat loss and fragmentation are amongst the greatest threats to biodiversity world‐wide. However, there is still little evidence on the relative influence of these two distinct processes on biodiversity, and no study, to date, has investigated the independent contribution of structural connectivity in addition to habitat loss and fragmentation. The aim of this study is to evaluate the independent effects of habitat loss (the decrease in total amount of habitat), habitat fragmentation per se (habitat subdivision) and structural connectivity (in the form of hedgerow networks) on the distribution of seven resident forest‐dependent birds in central Italy. Location Central Italy. Methods We strategically selected 30 landscapes (each of 16 km² in size) with decreasing total amount of forest cover and with contrasting configuration of patches and contrasting lengths of hedgerow networks. Presence/absence of birds in each landscape unit was studied through point counts. Results The amount of forest cover in the landscape had the strongest relative influence on birds’ occupancy, whilst habitat subdivision played a negligible role. Structural connectivity and the geographic position of the landscape unit played a relatively important role for four species. Main conclusions Our study shows the importance of disentangling the contribution of different landscape properties in determining distribution patterns. Our results are consistent with the fact that halting habitat loss and carrying out habitat restoration should be conservation priorities, since habitat loss is the main factor affecting the distribution of the target species; implementation of structural connectivity through hedgerows, instead, should be evaluated with caution since its contribution is secondary to the predominant role of habitat loss.     

雉鸡(Phasianus colchicus)营巢生境的模拟分析研究

将多元统计学方法与地理信息系统结合对动物的栖息地进行适宜性分析,是近年动物栖息地研究者和管理者都十分感兴趣的方面。本研究采用马氏距离法,利用地理信息系统模拟甘肃雉鸡的营巢生境。模拟结果表明,与已知营巢生境相似水平为0.95的区域面积,仅占整个研究区的0.68%,而与已知营巢生境迥然不同（P＜0.05）的区域面积占79.08%。营巢生境与非营巢生境在生境类型组成和地形因素上存在多方差异,营巢生境中农田和草坡占有极大比例,用于营巢的区域总是更接近生境的边缘。特别是接近于农田、草坡和白桦阔叶林等生境,表明倾向于在这几种生境的边缘附近营巢。营巢生境的平均海拔比非营巢生境低,坡度也较缓,坡向则更偏于东南方。在同一生境类型内部,用于营巢的区域和不利用的区域之间也存在很大差别,营巢区域总是更接近生境的边缘。某一生境周围的其它生境类型也会影响雉鸡的营巢选择。     

冬虫夏草与产地植物及土壤的重金属含量测定

本文测定了野生采集和人工培育冬虫夏草、人工培育冬虫夏草子实体、冬虫夏草发酵菌液、冬虫夏草寄主蝙蝠蛾昆虫食物(蕨麻Potentilla anserine和珠芽蓼Polygonum viviparum),以及野生冬虫夏草产地土壤中5种重金属元素(铜Cu、铅Pb、砷As、镉Cd、汞Hg)的含量。结果表明,人工培育冬虫夏草、人工培育冬虫夏草子实体、冬虫夏草发酵菌液、蕨麻块根、珠芽蓼种子的5种重金属元素含量符合《中医药-中药材重金属限量》ISO国际标准;而野生冬虫夏草,除砷含量(6.170 mg/kg)超标外,铜、铅、镉、汞元素含量均符合要求。按国家标准《土壤环境质量农用地土壤污染风险管控标准(试行)》(GB 1516-2018),四川产地土壤(KDX)与青海产地土壤(GD、HN)的5种重金属含量均低于农用土壤污染风险筛选值;而四川产地土壤(KDT),除镉含量(0.923 mg/kg)高于风险筛选值而低于风险管制值外,其余4种元素含量均低于风险筛选值。结果为人工培育冬虫夏草的质量控制提供了参考。     

基于生境可获得性的完达山地区马鹿(Cervus elaphus xanthopygus)冬季生境选择

于2004～2005年冬季研究了完达山地区马鹿的生境利用和选择。在野外调查的基础上,获取了研究地区马鹿种群水平上的生境利用数据;利用地理信息系统和遥感技术,从区域尺度上测度了各类生境因子的可获得性。通过比较被利用生境与可获得生境,测度了马鹿冬季对各类生境或生态因子的选择。结果表明,马鹿对植被类型、海拔、坡向、NDVI等级、到公路距离表现出非比例利用,对坡度的利用与其可获得性则没有显著性差异。马鹿选择采伐迹地,低郁闭度生境（第2、3NDVI等级）,200～300m海拔区间,南坡,距离公路600～700m的区间。马鹿采食生境和卧息生境对各类因子具有不同的选择性,表现出不同功能生境分离的特征。对于采食生境,马鹿选择采伐迹地、阔叶疏林,低郁闭度（第2、3NDVI等级）,南坡;对于卧息生境,马鹿仅选择采伐迹地,低郁闭度（第2、3、4NDVI等级）。根据马鹿活动样点的出现与否,建立了马鹿冬季生境选择的逻辑斯谛回归模型。模型回判结果表明,该模型对马鹿活动样方与对照样方的总体正确预测率为74．4％,对马鹿活动样方的正确预测率为84．2％,对对照样方的正确预测率为62．4％,能够较好的预测生境利用概率。     

栖息地荒漠化对蜥蜴群落组成的影响

栖息地改变往往对动物群落及其物种多样性有重要影响,但是目前关于栖息地荒漠化如何影响蜥蜴的群落组成鲜有研究。在内蒙古自治区鄂尔多斯市准格尔旗和达拉特旗地区通过样线法调查了三类不同荒漠化程度样地上的蜥蜴群落组成差异,用典范对应分析探究了关键的影响因素。结果表明,栖息地荒漠化使蜥蜴的群落组成发生显著变化,从固定沙丘、半固定沙丘到流动沙丘,草原沙蜥均是蜥蜴群落的优势物种,密点麻蜥逐渐减少,丽斑麻蜥则消失于荒漠化严重的半固定沙丘和流动沙丘中。随栖息地荒漠化程度的增加,蜥蜴的数量显著减少,密度显著降低,蜥蜴物种的丰富度、香农-威纳(Shannon-Weaver)多样性指数和皮洛(Pielou)均匀性指数均逐次显著下降,而辛普森(Simpson)优势度指数则逐次显著升高。这说明荒漠化不仅使蜥蜴群落组成变得简单,同时造成了蜥蜴物种多样性的下降甚至丧失。荒漠化也使蜥蜴的栖息条件发生显著变化。植被高度、油蒿比例、裸地比例、隐蔽度、表层土壤含水量和表层土壤孔隙度在三类栖息样地之间均存在极显著差异。典范对应分析结果表明,这些环境因子与蜥蜴群落组成的变化密切相关。总体而言,草原沙蜥偏好裸地,密点麻蜥偏好隐蔽性好且土壤湿润又疏松的区域,而丽斑麻蜥则偏好植被高的区域。     

京杭运河邵伯高邮段栖息地破碎化对狗獾种群数量分布的影响

栖息地破碎是生物多样性下降的主要原因之一。栖息地破碎引起的面积效应、隔离效应和边缘效应能影响动物种群的绝灭阈值、分布、多度、种间关系以及生态系统过程, 最终影响动物种群的数量分布。2006年10-11月和2007年10-11月, 利用全球定位系统(GPS)、地理信息系统(GIS)和样方法定量分析京杭运河邵伯至高邮段狗獾栖息地破碎化程度, 确定不同斑块的面积、斑块距离、斑块隔离度以及栖息地质量对斑块中狗獾数量分布的影响。结果表明, 各个斑块内狗獾的洞口数、粪堆数与该斑块的面积显著的正相关(r=0.961, P=0.039; r=0.999, P=0.023), 但与斑块距离、斑块隔离度无显著的相关性(P>0.05)。栖息地的质量也会影响狗獾的数量分布, 多元线性逐步回归分析表明, 人类干扰和与栖息地的郁闭性显著的影响狗獾的数量分布。以上结果说明, 京杭运河邵伯高邮段栖息地的破碎化程度对狗獾的数量分布还没有造成显著的直接影响, 但会间接降低栖息地的质量, 进而影响狗獾的生存。     

Effects of habitat complexity,dominance and personality on habitat selection: Ideal despotic cichlids

Habitat structure can impede visibility and movement, resulting in lower resource monopolization and aggression. Consequently, dominant individuals may prefer open habitats to maximize resource gain, or complex habitats to minimize predation risk. We explored the role of dominance on foraging, aggression and habitat choice using convict cichlids (Amatitlania nigrofasciata) in a two‐patch ideal free distribution experiment. Groups of six fish of four distinct sizes first competed for shrimp in one‐patch trials in both an open and complex habitat; half the groups experienced each habitat type first. Following these one‐patch trials, each group then chose between habitat types in a two‐patch trial while competing for food. Finally, each fish underwent an individual behavioural assessment using a battery of “personality” tests to determine if behaviour when alone accurately reflected behaviour within a social context. In the one‐patch trials, dominant fish showed similar food consumption between habitats, but chased more in the complex habitat. In the two‐patch choice trials, dominants preferred and defended the complex habitat, forming an ideal despotic distribution with more than half the fish and competitive weight in the open habitat. Within the groups, individual fish differed in foraging and chasing, with repeatabilities of 0.45 and 0.23 across all treatments. Although a higher foraging rate during the individual assessment predicted foraging rate and use of the complex habitat during the group trials, aggression and boldness tests were not reflective of group behaviour. Across groups, heavier dominants and those with higher foraging rate in the open habitat used the open habitat more, suggesting that both risk and energetic state affect habitat preference in dominant convict cichlids.     

Spatial heterogeneity and habitat configuration overcome habitat composition influences on alpha and beta mammal diversity

The effects of habitat fragmentation on different taxa and ecosystems are subject to intense debate, and disentangling them is of utmost importance to support conservation and management strategies. We evaluated the importance of landscape composition and configuration, and spatial heterogeneity to explain α- and β-diversity of mammals across a gradient of percent woody cover and land use diversity. We expected species richness to be positively related to all predictive variables, with the strongest relationship with landscape composition and configuration, and spatial heterogeneity respectively. We also expected landscape to influence β-diversity in the same order of importance expected for species richness, with a stronger influence on nestedness due to deterministic loss of species more sensitive to habitat disturbance. We analyzed landscape structure using: (a) landscape metrics based on thematic maps and (b) image texture of a vegetation index. We compared a set of univariate explanatory models of species richness using AIC, and evaluated how dissimilarities in landscape composition and configuration and spatial heterogeneity affect β-diversity components using a Multiple Regression on distance Matrix. Contrary with our expectations, landscape configuration was the main driver of species richness, followed by spatial heterogeneity and last by landscape composition. Nestedness was explained, in order of importance, by spatial heterogeneity, landscape configuration, and landscape composition. Although conservation policies tend to focus mainly on habitat amount, we advocate that landscape management must include strategies to preserve and improve habitat quality and complexity in natural patches and the surrounding matrix, enabling landscapes to harbor high species diversity.     

Determining habitat quality for species that demonstrate dynamic habitat selection

Determining habitat quality for wildlife populations requires relating a species' habitat to its survival and reproduction. Within a season, species occurrence and density can be disconnected from measures of habitat quality when resources are highly seasonal, unpredictable over time, and patchy. Here we establish an explicit link among dynamic selection of changing resources, spatio‐temporal species distributions, and fitness for predictive abundance and occurrence models that are used for short‐term water management and long‐term restoration planning. We used the wading bird distribution and evaluation models (WADEM) that estimate (1) daily changes in selection across resource gradients, (2) landscape abundance of flocks and individuals, (3) conspecific foraging aggregation, and (4) resource unit occurrence (at fixed 400 m cells) to quantify habitat quality and its consequences on reproduction for wetland indicator species. We linked maximum annual numbers of nests detected across the study area and nesting success of Great Egrets (Ardea alba), White Ibises (Eudocimus albus), and Wood Storks (Mycteria americana) over a 20‐year period to estimated daily dynamics of food resources produced by WADEM over a 7490 km² area. For all species, increases in predicted species abundance in March and high abundance in April were strongly linked to breeding responses. Great Egret nesting effort and success were higher when birds also showed greater conspecific foraging aggregation. Synthesis and applications: This study provides the first empirical evidence that dynamic habitat selection processes and distributions of wading birds over environmental gradients are linked with reproductive measures over periods of decades. Further, predictor variables at a variety of temporal (daily‐multiannual) resolutions and spatial (400 m to regional) scales effectively explained variation in ecological processes that change habitat quality. The process used here allows managers to develop short‐ and long‐term conservation strategies that (1) consider flexible behavioral patterns and (2) are robust to environmental variation over time.     

Dispersing brush mice prefer habitat like home

During natal dispersal, young animals leave their natal area and search for a new area to live. In species in which individuals inhabit different types of habitat, experience with a natal habitat may increase the probability that a disperser will select the same type of habitat post-dispersal (natal habitat preference induction or NHPI). Despite considerable interest in the ecological and the evolutionary implications of NHPI, we lack empirical evidence that it occurs in nature. Here we show that dispersing brush mice (Peromyscus boylii) are more likely to search and settle within their natal habitat type than expected based on habitat availability. These results document the occurrence of NHPI in nature and highlight the relevance of experience-generated habitat preferences for ecological and evolutionary processes.     

Species richness and food web structure of soil decomposer community as affected by the size of habitat fragment and habitat corridors

While most ecologists agree that the effects of fragmentation on diversity of organisms are predominantly negative and that the scale of fragmentation defines their severity, the role of habitat corridors in mitigating those effects still remains controversial. This ambiguousness rests largely on various difficulties in experimentation, a problem partially solved in the present paper by the use of easily manipulated soil communities. In this 2.5‐year‐long field experiment, we investigated the responses of soil decomposer organisms (from microbes to mesofaunal predators) to habitat fragment size, in the presence or absence of habitat corridors connecting the fragments. The habitat fragments and corridors, composed of forest humus soil, were embedded in mineral soil representing an uninhabitable (or nonpreferred) matrix for the decomposer organisms. The results demonstrate that soil decomposer organisms do respond to changes in their habitat size: the species richness of microarthropods (mites and collembolans) increased as the size of the fragments increased. Especially collembolan species and predatory mites proved to be sensitive to the restricted habitat size, which is suggested to be a consequence of the large proportion of rare species and small and fluctuating population sizes in these groups. Contrary to our expectations, the presence of corridors had no positive effects on species richness or abundance of any of the studied faunas, possibly because of the low quality of the corridors. On the other hand, the biomass of soil fungi increased in the presence of corridors, which apparently provided a preferred pathway for vegetative dispersal of the fungi. Our results indicate that despite their characteristic underground environment, the response of soil decomposer organisms – in particular that of microarthropods – to habitat size is not unlike to that of the larger organisms in aboveground habitats.     

Ranging patterns and habitat use of Sulawesi Tonkean macaques (Macaca tonkeana) in a human-modified habitat

The goal of this study was to investigate the ecological flexibility of Tonkean macaques (Macaca tonkeana) by examining how they respond to human-induced habitat alteration. To do so, I observed movement patterns, forest strata use, microhabitat use, and home range use in two groups that occupied habitats with different levels of human alteration and habitat quality in Lore Lindu National Park, Sulawesi, Indonesia. The group occupying the heavily altered habitat (Anca) spent a significantly greater proportion of time traveling on the ground than the group in minimally altered habitat (CH), and significantly more time than expected in microhabitats within their range that were characterized by greater alteration (e.g., agroforestry areas). There was no significant difference between the two groups in daily path length, despite differences in group size. The Anca group exhibited a greater home range area per individual than the CH group, and utilized a more limited area within their home range with greater intensity, relative to the CH group. Tonkean macaques therefore show considerable flexibility in response to anthropogenic disturbance by adjusting their use of forest strata to facilitate travel and increase foraging opportunities and by intensively using particular areas within their home range where known resources are present and predictably available.     

Relation to habitat in rotifers

Rotifera should be especially suited for an analysis of habitat relations because this group contains such a high number of species, inhabiting diverse environments. Furthermore, rotifers are to a large extent cosmopolitan, implying that ecological barriers, rather than geographical, are decisive of their distribution. In this review a short characterization of the rotifer fauna in different habitats is given, whereby macroenvironments and microenvironments are reported separately. The macroenvironments are classified as follows: harmonious lakes and ponds, arctic and antarctic waters, hot springs, hypertrophic-saprobic environments, mires, strongly acidic waters, saline waters, temporary water bodies, subterranean waters, running waters, oceans, terrestrial environments. The following microenvironments are distinguished: macrophytes (housing periphytic rotifers), open water (with planktic forms), minerogenous sediments (with psammon and hyporheos), organogenous sediments, other organisms (i.e. parasites and epizoans).Many rotifers are more or less euryecious, while relatively few are strongly restricted in their choice of habitat. In extreme environments a low number of species is found, but often a high number of individuals within these species. These rotifers are usually primary consumers, and for natural reasons extreme environments are characterized by a low number of trophic levels.In environments with a high species number the separate species differ very much in their morphology, making it difficult to find common traits which may be interpreted as adaptations to the respective habitats. The most apparent adaptations ought to be found among the planktic rotifers, and these adaptations seem to constitute largely a protection against predators. Rotifers in extreme environments are usually not very apart in a morphological or taxonomical respect, with their most close relatives living in normal habitats and sometimes euryecious (an apparent exception from this rule is formed by the class Seisonidea). Adaptations to deviating chemical and physical environments may develop relatively rapidly (seen from a geological perspective), while the more fundamental changes (occurring during a longer period of time) seem to be a response to biotic factors (e.g., the development of different types of trophi for facilitating food collection).     

A potential habitat network for the Eurasian lynx Lynx lynx in Scotland

• 1 The severe and early destruction and fragmentation of woodland habitats due to human activities is thought to have been a leading factor in the extirpation from Britain of several large, forest‐dependent mammal species, such as the Eurasian lynx Lynx lynx. However, during the 20th century, Scotland in particular has experienced rapid, large‐scale reafforestation. In order to assess if this reafforestation has been sufficient to permit the potential restoration of extirpated forest mammal species with large spatial requirements, a Geographical Information System (GIS) analysis of potential habitat of one species, the Eurasian lynx, was performed for the Scottish mainland.
• 2 A rule‐based analysis, incorporating data and expert opinion from Switzerland, an environmentally similar area where lynx now occur, was used to identify patches of suitable lynx habitat in Scotland. A connectivity analysis was used to investigate whether and how these patches are connected to form larger interconnected networks of potential lynx habitat that would allow lynx to sufficiently interact with one another to form a single interbreeding population.
• 3 Scotland has over 20 000 km² of suitable lynx habitat split into two main networks of interconnected patches: the Highlands (c. 15 000 km²) and the Southern Uplands (c. 5000 km²). A further 800 km² of potential habitat, contiguous with the Southern Uplands lynx habitat network, lies across the border in England. Although connectivity between the Highlands and Southern Uplands networks is currently weak, the implementation of measures to mitigate the barrier effects of busy roads in central Scotland could facilitate the movement of lynx between the two areas.
• 4 Based on the availability of prey resources, Scotland could support around 400 adult and subadult lynx in the Highlands and around 50 in the Southern Uplands. A Scottish population of this size would be the fourth largest lynx population in Europe considering current population estimates.

     

Responses of two species of heathland rodents to habitat manipulation: Vegetation density thresholds and the habitat accommodation model

The abundance of two native rodent species, Rattus lutreolus and Pseudomys gracilicaudatus, has been shown to correlate with vegetation density in coastal wet heath. Fox's habitat accommodation model relates relative abundances of such small mammal species to heathland vegetation regeneration following disturbance. Implicit in the model is recognition that it is successional changes in vegetation, not time per se, that drives the responses of small mammal species along a regeneration axis. Using a brush‐cutter we deliberately removed approximately 85% of vegetation around trapping stations and recorded significant reductions in the abundance of both P. gracilicaudatus (an earlier‐stage colonizing species) and R. lutreolus (a late seral‐stage species). A significant decrease in the abundance of only the latter had been demonstrated previously when 60–70% of the vegetation had been removed. Following the brush‐cutting both species re‐entered the mammalian secondary succession at different times, first P. gracilicaudatus followed by R. lutreolus after the vegetation cover thresholds of each species had been reached. The impact of this habitat manipulation experiment was to produce a retrogression of the small mammal succession, experimentally demonstrating causality between changes in vegetation density and subsequent small mammal habitat use.