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Local Habitat (local + habitat)

Distribution by Scientific Domains

Life Sciences	93%

Distribution within Life Sciences

Ecology & Organismal Biology	35%
Conservation Science	13%

Selected Abstracts

Trophic level modulates carabid beetle responses to habitat and landscape structure: a pan-European study

ECOLOGICAL ENTOMOLOGY, Issue 2 2010
ADAM J. VANBERGEN
1. Anthropogenic pressures have produced heterogeneous landscapes expected to influence diversity differently across trophic levels and spatial scales. 2. We tested how activity density and species richness of carabid trophic groups responded to local habitat and landscape structure (forest percentage cover and habitat richness) in 48 landscape parcels (1 km2) across eight European countries. 3. Local habitat affected activity density, but not species richness, of both trophic groups. Activity densities were greater in rotational cropping compared with other habitats; phytophage densities were also greater in grassland than forest habitats. 4. Controlling for country and habitat effects, we found general trophic group responses to landscape structure. Activity densities of phytophages were positively correlated, and zoophages uncorrelated, with increasing habitat richness. This differential functional group response to landscape structure was consistent across Europe, indicated by a lack of a country × habitat richness interaction. Species richness was unaffected by landscape structure. 5. Phytophage sensitivity to landscape structure may arise from relative dependency on seed from ruderal plants. This trophic adaptation, rare in Carabidae, leads to lower phytophage numbers, increasing vulnerability to demographic and stochastic processes that the greater abundance, species richness, and broader diet of the zoophage group may insure against. [source]

Multispecies and Multiscale Conservation Planning: Setting Quantitative Targets for Red-Listed Lichens on Ancient Oaks

CONSERVATION BIOLOGY, Issue 3 2010
HEIDI PALTTO
bosque de encino maduro; cantidad de hábitat; encino antiguo; escala espacial; líquenes en la lista roja Abstract:,Species occurrence in a habitat patch depends on local habitat and the amount of that habitat in the wider landscape. We used predictions from empirical landscape studies to set quantitative conservation criteria and targets in a multispecies and multiscale conservation planning effort. We used regression analyses to compare species richness and occurrence of five red-listed lichens on 50 ancient oaks (Quercus robur; 120,140 cm in diameter) with the density of ancient oaks in circles of varying radius from each individual oak. Species richness and the occurrence of three of the five species were best explained by increasing density of oaks within 0.5 km; one species was best explained by the density of oaks within 2 km, and another was best predicted by the density of oaks within 5 km. The minimum numbers of ancient oaks required for "successful conservation" was defined as the number of oaks required to obtain a predicted local occurrence of 50% for all species included or a predicted local occurrence of 80% for all species included. These numbers of oaks were calculated for two relevant landscape scales (1 km2 and 13 km2) that corresponded to various species responses, in such a way that calculations also accounted for local number of oaks. Ten and seven of the 50 ancient oaks surveyed were situated in landscapes that already fulfilled criteria for successful conservation when the 50% and 80% criteria, respectively, were used to define the level of successful conservation. For cost-efficient conservation, oak stands in the landscapes most suitable for successful conservation should be prioritized for conservation and management (e.g., grazing and planting of new oaks) at the expense of oak stands situated elsewhere. Resumen:,La ocurrencia de especies en un parche de hábitat depende del hábitat local y de la cantidad de ese hábitat en un paisaje más amplio. Utlizamos predicciones de estudios de paisaje empíricos para definir criterios y objetivos de conservación cuantitativos en un esfuerzo de planificación de la conservación para múltiples especies y escalas. Utilizamos análisis de regresión para comparar la riqueza y ocurrencia de especies de cinco líquenes en la lista roja sobre 20 encinos antiguos (Quercus robur; 120,140 cm de diámetro) con la densidad de encinos antiguos en círculos de radio variable desde cada encino individual. La riqueza y ocurrencia de tres de las cinco especies fue mejor explicada por el incremento de la densidad de encinos en 0.5 km; una especie fue mejor explicada por la densidad de encinos en 2 km, y la otra fue mejor pronosticada por la densidad de encinos en 5 km. Los números mínimos de encinos antiguos requeridos para una "conservación exitosa" fueron definidos como el número de encinos requeridos para obtener una ocurrencia local pronosticada de de 50% para todas las especies incluidas o una ocurrencia local pronosticada de 80% para todas las especies incluidas. Estos números de encinos fueron calculados para dos escalas de paisaje relevantes (1 km2 y 13 km2) que correspondieron a las respuestas de varias especies, de tal modo que los cálculos también incluyeron el número local de encinos. Diez y siete de los 50 encinos antiguos estaban situados en paisajes que ya cumplían criterios para conservación exitosa cuando los criterios de 50% y 80%, respectivamente, fueron usados para definir el nivel de conservación exitosa. Para una conservación redituable, los bosques de encinos en los paisajes más aptos para la conservación exitosa deberían ser priorizados para conservación y manejo (e. g., pastoreo y siembra de encinos nuevos) a costa de bosques de encino situados en otros lados. [source]

Effects of landscape structure and habitat type on a plant-herbivore-parasitoid community

ECOGRAPHY, Issue 3 2003
Andreas Kruess
The effects of local habitat and large-scale landscape factors on species diversity and species interactions were studied using the insect community in stems of the creeping thistle Cirsium arvense. Thistle abundance was higher in fallows than in crop fields and field margins, with fallows providing 67% of thistle abundance within 15 study areas on a landscape scale. Species richness of the herbivores was positively related with thistle abundance, parasitoid species richness was influenced by habitat type and was positively correlated with herbivore species richness. The abundance of herbivores and parasitoids was affected by local factors such as habitat type and host abundance, but also by landscape factors such as the percentage of non-crop area and the isolation of habitats. The infestation rate caused by the agromyzid Melanagromyza aeneoventris was positively related to percent non-crop area, whereas the parasitism rate of this fly increased with increasing habitat diversity on the landscape scale. For these two interactions and for total herbivore abundance, a scale-dependency of the landscape effects was found. The results emphasize that biological diversity and ecological functions within a plant-insect community are not only affected by local habitat factors but also by large-scale landscape characteristics. Hence, to improve future agri-environmental schemes for biodiversity conservation and biological control large-scale landscape effects and their scale-dependency should be considered. [source]

Trophic level modulates carabid beetle responses to habitat and landscape structure: a pan-European study

Temporal changes in replicated experimental stream fish assemblages: predictable or not?

FRESHWATER BIOLOGY, Issue 9 2006
WILLIAMJ.
Summary 1.,Natural aquatic communities or habitats cannot be fully replicated in the wild, so little is known about how initially identical communities might change over time, or the extent to which observed changes in community structure are caused by internal factors (such as interspecific interactions or traits of individual species) versus factors external to the local community (such as abiotic disturbances or invasions of new species). 2.,We quantified changes in seven initially identical fish assemblages, in habitats that were as similar as possible, in seminatural artificial streams in a 388-day trial (May 1998 to May 1999), and compared the change to that in fish assemblages in small pools of a natural stream during a year. The experimental design excluded floods, droughts, immigration or emigration. The experimental fish communities diverged significantly in composition and exhibited dissimilar trajectories in multivariate species space. Divergence among the assemblages increased from May through August, but not thereafter. 3.,Differences among the experimental assemblages were influenced by differences that developed during the year in algae cover and in potential predation (due to differential survival of sunfish among units). 4.,In the natural stream, fish assemblages in small pools changed more than those in the experimental units, suggesting that in natural assemblages external factors exacerbated temporal variation. 5.,Our finding that initially identical assemblages, isolated from most external factors, would diverge in the structure of fish assemblages over time suggests a lack of strong internal, deterministic controls in the assemblages, and that idiosyncratic or stochastic components (chance encounters among species; vagaries in changes in the local habitat) even within habitat patches can play an important role in assemblage structure in natural systems. [source]

Invertebrate community structure in streams of the Manawatu,Wanganui region, New Zealand: the roles of catchment versus reach scale influences

FRESHWATER BIOLOGY, Issue 8 2004
Russell G. Death
Summary 1. Invertebrate communities at 187 least impacted streams in the Manawatu,Wanganui region of New Zealand were sampled between February and May 2000 to investigate the relative influence of catchment and reach scale environmental influences on community structure. 2. Of the 138 biological (fish and periphyton), local habitat and catchment scale descriptors used to examine invertebrate community patterns, alkalinity and conductivity were the most consistently influential predictors. 3. Of the 52 geographical information system (GIS)-derived catchment variables (catchment geology, catchment land use, rainfall and topography) only per cent catchment in pasture, indigenous forest, coastal sand, crushed argillite and wind blown sand were associated with any measures of the invertebrate communities. 4. Grouping of communities based on GIS data in general, did not generate distinct community types. Groupings based on river catchment, conductivity and alkalinity however, did produce distinct communities. 5. Streams with very low alkalinity were dominated by Ephemeroptera, Plecoptera and Trichoptera that were gradually replaced by Mollusca, Crustacea and Chironomidae as alkalinity increases. 6. Habitat characteristics measured at the scale of the reach were more closely linked with measures of invertebrate community structure than any GIS derived variables or river classifications. [source]

Factors affecting nest predation on forest songbirds in North America

IBIS, Issue 2007
FRANK R. THOMPSON III
Nest predation is an important factor in the ecology of passerines and can be a large source of mortality for birds. I provide an overview of factors affecting nest predation of passerines in North America with the goal that it may provide some insight into the ecology and management of woodland birds in the United Kingdom. Although several factors influence productivity, nest success is perhaps the most widely measured demographic characteristic of open-cup-nesting birds, and nest predation is usually the largest cause of nest failure. The identity of predator species, and how their importance varies with habitat and landscape factors, must be known for managers and scientists to design effective conservation plans and place research on nest predation in the appropriate context. Recent studies using video surveillance have made significant contributions to our understanding of the relative importance of different predator taxa in North America. Spatial and temporal variation in nest predation can be better understood when landscapes are placed in a biogeographical context and local habitat and nest-site effects are placed in a landscape context. Low productivity resulting from high nest predation is one of several potential causes of bird population declines in North America and the UK. Although the ,forest fragmentation paradigm' from the eastern US may not apply directly to the UK, thinking about avian demographics from a multiscale perspective, and consideration of factors affecting nest predation with knowledge of the dominant predator species, may provide insight into population declines. [source]

Structure of Macroinvertebrate Communities in Relation to Environmental Variables in a Subtropical Asian River System

INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 1 2010
Xiao-Ming Jiang
Abstract Subtropical Asian rivers support a highly diverse array of benthic macroinvertebrates. Yet, their biodiversity and functionality has been poorly investigated. We choose the Chishui River system, one of the largest un-dammed, first level branches upstream of the Yangtze River, China, to: 1) determine the spatial pattern of macroinvertebrate diversity and community structure, and 2) examine the influence of variables at local habitat and basin scales on the distribution of macroinvertebrate communities. Samples were collected from 43 sites in spring of 2007. After Canonical Correspondence Analysis, two basin and five habitat variables were found to be significant predictors of the macroinvertebrate community structure. Variance partitioning analysis showed that habitat physical variables had a greater influence than other environmental variables in macroinvertebrate community, which suggested that preserving habitat, especially upstream, should be strongly considered in biological conservation. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Habitat preferences of European grayling in a medium size stream, the Ain river, France

JOURNAL OF FISH BIOLOGY, Issue 6 2000
J. P. Mallet
The three grayling Thymallus thymallus age-classes had strong preferences for their local habitat in the Ain river. All age-classes preferred high water velocities between 70 and 110 cm s -1, confirming that grayling is a typical rheophilic species. An important intraspecific segregation regarding depth occurred, as large individuals preferred deeper water than small ones (optimal ranges=50,60, 80,120 and 100,140 cm for 0+, 1+ and adults respectively). The three age-classes had similar preferences for small substratum articles, with optimal values between 0·5 and 16·0 mm. Preference curves were generally comparable between the two sites, despite important differences in habitat availability. It is emphasized that grayling needs various habitat conditions to achieve its entire life cycle. The increasing scarcity of this species underlines the urgency of protecting lotic habitat integrity and diversity. [source]

Long-term change to fish assemblages and the flow regime in a southeastern U.S. river system after extensive aquatic ecosystem fragmentation

ECOGRAPHY, Issue 6 2008
Christopher M. Taylor
The upper Tombigbee River in northeastern Mississippi now exists as a fragment, confluencing with and fed by an extensively modified aquatic landscape now called the Tennessee-Tombigbee Waterway (TTW). We examined the changes to fish assemblages and flow regime after waterway construction based on contemporary comparisons to historical fish collections and discharge data. The river's flow regime has changed markedly since TTW construction. Analysis of discharge data from two stations for 15 years, pre- and post-waterway, indicated significant differences in flow regime including increased minimum and base flows, lower spring and higher late summer-autumn flows, and lower high flow durations, post-TTW. These changes corresponded to significantly reduced regional and local species richness, and strong shifts in fish assemblage structure across a 20 yr time span. Post-waterway fish assemblages were related strongly to measured environmental variables characterizing local habitats. Several lentic-adapted species increased their abundances in lower reaches of the river, including a recent invader to the TTW system, the Mississippi silverside Menidia audens. Fragmentation of river ecosystems via disruption to hydrologic regimes is a major threat to aquatic biodiversity worldwide. Because the flow regime of this fragmented river is in part controlled by waterway operations via five minimum flow control structures, adaptive conservation and management efforts could be implemented in order to maintain and potentially restore the natural flow regime and the ecological integrity of the system. [source]

Plant species response to land use change ,Campanula rotundifolia, Primula veris and Rhinanthus minor

ECOGRAPHY, Issue 1 2005
Regina Lindborg
Land use change is a crucial driver behind species loss at the landscape scale. Hence, from a conservation perspective, species response to habitat degradation or improvement of habitat quality, is important to examine. By using indicator species it may be possible to monitor long-term survival of local populations associated with land use change. In this study we examined three potential indicator (response) species for species richness and composition in Scandinavian semi-natural grassland communities: Campanula rotundifolia, Primula veris and Rhinanthus minor. With field inventories and experiments we examined their response to present land use, habitat degradation and improvement of local habitat quality. At the time scale examined, C. rotundifolia was the only species responding to both habitat degradation and improvement of habitat quality. Neither R. minor nor P. veris responded positively to habitat improvements although both responded rapidly to direct negative changes in habitat quality. Even though C. rotundifolia responded quickly to habitat degradation, it did not disappear completely from the sites. Instead, the population structure changed in terms of decreased population size and flowering frequency. It also showed an ability to form remnant populations which may increase resilience of local habitats. Although P. veris and especially R. minor responded rapidly to negative environmental changes and may be useful as early indicators of land use change, it is desirable that indicators respond to both degradation and improvement of habitat quality. Thus, C. rotundifolia is a better response species for monitoring effects of land use change and conservation measures, provided that both local and regional population dynamics are monitored over a long time period. [source]

Influence of Age and Prior Experience on Territorial Behavior and the Costs of Defense in Male Collared Lizards

ETHOLOGY, Issue 1 2007
Andrew M. Schwartz
In polygynous species where males maintain strong interseasonal philopatry to the same breeding territories, older individuals have prior experience defending their areas, whereas younger individuals are defending a territory for the first time. Theoretical and empirical studies predict that under such conditions the cumulative costs of defense may be lower for older experienced males as a consequence of familiarity with environmental and/or social conditions in their particular local habitats. We used quantitative data from focal observational studies and introduction experiments to test the hypothesis that older collared lizard males (Crotaphytus collaris) with prior territorial experience (3 yr+ males) acquire larger territories allowing them to court more, different females, with greater frequency without incurring higher defense costs. Consistent with this hypothesis, 3 yr+ males controlled significantly larger territories and courted more females, without having significantly higher rates of territory patrol, frequencies of advertisement display, or aggressive interactions with same-sex competitors. Moreover, the intensity of responses to size- and age/experience-matched tethered intruders by 3 yr+ males was lower than that by 2 yr males in their first season of territory defense. Our results support the hypothesis that age/prior occupancy of territories lowers defense costs allowing males to defend larger areas and increase opportunities to court females, perhaps increasing mating opportunities. By contrast, 2 yr males may need to respond more aggressively to intruders because their ownership of territories is tenuous as a consequence of shorter territory occupancy. [source]

Detecting local adaptation in widespread grassland species , the importance of scale and local plant community

JOURNAL OF ECOLOGY, Issue 6 2006
ARMIN BISCHOFF
Summary 1Adaptation of plant populations to local environments has been shown in many species but local adaptation is not always apparent and spatial scales of differentiation are not well known. In a reciprocal transplant experiment we tested whether: (i) three widespread grassland species are locally adapted at a European scale; (ii) detection of local adaptation depends on competition with the local plant community; and (iii) local differentiation between neighbouring populations from contrasting habitats can be stronger than differentiation at a European scale. 2Seeds of Holcus lanatus, Lotus corniculatus and Plantago lanceolata from a Swiss, Czech and UK population were sown in a reciprocal transplant experiment at fields that exhibit environmental conditions similar to the source sites. Seedling emergence, survival, growth and reproduction were recorded for two consecutive years. 3The effect of competition was tested by comparing individuals in weeded monocultures with plants sown together with species from the local grassland community. To compare large-scale vs. small-scale differentiation, a neighbouring population from a contrasting habitat (wet-dry contrast) was compared with the ,home' and ,foreign' populations. 4In P. lanceolata and H. lanatus, a significant home-site advantage was detected in fitness-related traits, thus indicating local adaptation. In L. corniculatus, an overall superiority of one provenance was found. 5The detection of local adaptation depended on competition with the local plant community. In the absence of competition the home-site advantage was underestimated in P. lanceolata and overestimated in H. lanatus. 6A significant population differentiation between contrasting local habitats was found. In some traits, this small-scale was greater than large-scale differentiation between countries. 7Our results indicate that local adaptation in real plant communities cannot necessarily be predicted from plants grown in weeded monocultures and that tests on the relationship between fitness and geographical distance have to account for habitat-dependent small-scale differentiation. Considering the strong small-scale differentiation, a local provenance from a different habitat may not be the best choice in ecological restoration if distant populations from a more similar habitat are available. [source]

The ecology and evolutionary endocrinology of reproduction in the human female

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue S49 2009
Virginia J. Vitzthum
Abstract Human reproductive ecology (HRE) is the study of the mechanisms that link variation in reproductive traits with variation in local habitats. Empirical and theoretical contributions from biological anthropology, physiology, and demography have established the foundation necessary for developing a comprehensive understanding, grounded in life history theory (LHT), of temporal, individual, and populational variation in women's reproductive functioning. LHT posits that natural selection leads to the evolution of mechanisms that tend to allocate resources to the competing demands of growth, reproduction, and survival such that fitness is locally maximized. (That is, among alternative allocation patterns exhibited in a population, those having the highest inclusive fitness will become more common over generational time.) Hence, strategic modulation of reproductive effort is potentially adaptive because investment in a new conception may risk one's own survival, future reproductive opportunities, and/or current offspring survival. The hypothalamic-pituitary-ovarian (HPO) axis is the principal neuroendocrine pathway by which the human female modulates reproductive functioning according to the changing conditions in her habitat. Adjustments of reproductive investment in a potential conception are manifested in temporal and individual variation in ovarian cycle length, ovulation, hormone levels, and the probability of conception. Understanding the extent and causes of adaptive and non-adaptive variation in ovarian functioning is fundamental to ascertaining the proximate and remote determinants of human reproductive patterns. In this review I consider what is known and what still needs to be learned of the ecology of women's reproductive biology, beginning with a discussion of the principal explanatory frameworks in HRE and the biometry of ovarian functioning. Turning next to empirical studies, it is evident that marked variation between cycles, women, and populations is the norm rather than an aberration. Other than woman's age, the determinants of these differences are not well characterized, although developmental conditions, dietary practices, genetic variation, and epigenetic mechanisms have all been hypothesized to play some role. It is also evident that the reproductive functioning of women born and living in arduous conditions is not analogous to that of athletes, dieters, or even the lower end of the "normal range" of HPO functioning in wealthier populations. Contrary to the presumption that humans have low fecundity and an inefficient reproductive system, both theory and present evidence suggest that we may actually have very high fecundity and a reproductive system that has evolved to be flexible, ruthlessly efficient and, most importantly, strategic. Yrbk Phys Anthropol 52:95,136, 2009. © 2009 Wiley-Liss, Inc. [source]

Distribution and underground habitats of cave-dwelling bats in China

ANIMAL CONSERVATION, Issue 4 2007
H. Niu
Abstract To understand the distribution and relative abundance of cave-dwelling bats and to identify those sites that would be important for conservation of bat species, 25 underground sites that had not been previously surveyed were investigated in this 3-year study (from December 2003 to April 2006) in Funiu Mountain of Henan province, China. Approximately 80 000 bats were recorded, representing 12 species. The most abundant species were Rhinolophus affinis, Miniopterus schreibersi and Hipposideros pratti. The roosts were evaluated for their conservation importance. The most important sites in the area are Yunhua and Nanzhao caves, which serve as hibernaculums and nursery roosts to c. 13 740 and 11 803 bats, respectively, representing seven species. By means of cluster and correspondence analysis, the distribution of bat species was different between the two sides of the mountain and was highly dependent on the size of the cave. The underground sites in the south region hosted c. 80% of the total bats, representing 11 species. The sites in the north region hosted 20% of the total bats, representing seven species. Presently, none of the caves in the region has adequate protection and some bat populations are under serious threat. Many large caves that contained large bat populations and several species of concern had been developed as tourist sites, and so some advice on protecting the most important local habitats was sought based on the assessment of the conservation status of underground sites. This paper presents basic data concerning the distribution of cave-dwelling bats and the patterns of cave use on Funiu Mountain. The data will help local governments and policy-makers develop suitable strategies to promote local tourisms while protecting important habitats of animal species. [source]