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101.
Conservation strategies should be based on a solid understanding of processes underlying species response to landscape change.
In forests fragmented by agriculture, elevated nest predation rates have been reported in many forest bird species, especially
near edges. In intensively-managed forest landscapes, timber harvesting might also be associated with negative edge effects
or broader “context” effects on some species when the matrix provides additional resources to their major nest predators.
In this study, we hypothesized that proximity to a forest edge and proportion of cone-producing plantations will increase
nest predation risk in fragments of relatively undisturbed forest. We focused on the Brown Creeper (Certhia americana), an indicator species of late-seral forests. We compared habitat configuration and composition at four spatial scales (0.14,
0.5, 1 and 2 km) around 54 nests and related daily nest survival rate to the distance to the nearest forest edge, mean patch
size of late-seral forest (r = 141 m), proportion of non-forested lands (r = 141 m), density of maintained roads (r = 1 km), proportion of cone-producing spruce plantations (r = 2 km), and year. The best model included distance to the nearest edge and proportion of cone-producing plantations. Distance
of nests to the nearest edge was the best individual predictor of daily nest survival. A larger sample of nests showed a significant
threshold in distance to the nearest forest edge; nests located at least 100 m away were more likely to fledge young. These
results suggest that even in managed forest landscapes, matrix effects can be important and some bird species may exhibit
negative edge effects. 相似文献
102.
Estelle Noyer Barbara Lachenbruch Jana Dlouhá Catherine Collet Julien Ruelle François Ningre Meriem Fournier 《Annals of Forest Science》2017,74(2):46
Key message
The position of trees in the canopy impacts xylem structure and its inter-annual variation. After canopy release, the increase in the hydraulic conductivity of growth rings was driven by an increase in radial growth in large trees, and by both an increase in radial growth and changes in xylem structure in saplings.Context
Forest canopies are frequently subjected to disturbances that allow understory trees to access the upper canopy. The effect of canopy release on xylem anatomy has been assessed in juvenile trees and saplings, while the potential acclimation of larger trees remains poorly documented.Aims
We estimated the potential hydraulic conductivity of growth rings in large understory trees compared to overstory trees, and evaluated the responses to canopy release in large trees and in saplings.Methods
We recorded radial growth, wood density, and vessel structure in beech trees according to their position within the canopy and their size. Xylem traits were followed during 6 years after canopy release for large trees, and during 2 years for saplings. Vessel diameter and frequency as well as ring area were used to compute the potential annual ring hydraulic conductivity.Results
Large understory trees displayed lower radial growth increments and lower potential annual ring hydraulic conductivity than overstory trees. After canopy release, potential annual ring hydraulic conductivity increased in large trees, due exclusively to increased radial growth without any change in specific hydraulic conductivity. It increased in saplings due to both increased radial growth and increased specific conductivity.Conclusion
Tree size impacted xylem structure and resulted in plasticity of the potential hydraulic conductivity of the annual tree ring following canopy release.103.
Aboveground vegetation, four belowground fauna groups and humus composition have been analyzed in order to investigate the links between autotrophic and heterotrophic communities in a Norway-spruce mountain forest in Tours-en-Savoie (France). The aboveground plant community was recorded in small patches corresponding to contrasting microhabitats. Animal communities and humus layers were sampled within the same patches. The relationships between humus profile, faunistic and floristic compositional gradients were investigated by Multiple Factor Analysis (MFA) and, for the first time in ecology, a Hierarchical Multiple Factor Analysis (HMFA) was used to interpret differences among humus layers. The analysis revealed a pattern with three main groups of microhabitats. The thorough study of separate humus layers could explain this result. The interplay of plant–animal–soil interactions is likely to drive the ecosystem toward three alternative states supporting humus traditional classification between mull–mor–moder. HMFA revealed the importance of depth to explain this contrast among humus forms, using humus layers as diagnostic tools in both inert and living components. HMFA also showed contrast between unexploited and exploited parts of the forest, but the study of soil and vegetation indicate that this contrast does not only hold in forest management but also in geomorphology. RV-coefficients among the six groups of variables showed significant fauna–fauna relationships in almost all humus layers except Actinedida. Plant–soil interactions are not as strong as expected and are even weaker when the soil in question is deep. In addition, HMFA failed to show direct interactions between plant and soil fauna but, paradoxically, HMFA does suggest that indirect plant–fauna interactions are at the focus of the ecosystem strategy that leads to the differentiation of ecological niches within the forest mosaic. 相似文献
104.
Comparison of 4 point‐of‐care blood gas analyzers for arterial blood gas analysis in healthy dogs and dogs with cardiopulmonary disease 下载免费PDF全文
105.
Marília Hauser Carolina R.C. Doria Roberto V. Santos Aurea García‐Vasquez Marc Pouilly Christophe Pcheyran Emmanuel Ponzevera Gislene Torrente‐Vilara Sylvain Brail Jacques Panfili Audrey Darnaude Jean‐Franois Renno Carmen García‐Dvila Jesus Nuez Franck Ferraton Gladys Vargas Fabrice Duponchelle 《水产资源保护:海洋与淡水生态系统》2019,29(3):397-408
106.
I. François F.‐X. Lalèyê M. Micat K. Benredouane K. Portier 《Equine veterinary journal》2014,46(5):596-600
107.
Responses of species to landscape modifications are generally documented through their distribution at a given time along
an intensity gradient of land transformation. By focusing on patterns, we are limited to infer ecological processes occurring
within a system and its response to environmental disturbances which can further change over time. Using diachronic datasets
at the scale of France, we analyzed the spatial responses of the black-billed magpie, which has recently colonized cities,
to landscape urbanization. This study applied recently developed statistical approaches incorporating detection uncertainty
of the magpie, based on the capture-recapture statistical framework. We tested whether, and how, extinction and colonization
mechanisms influenced variations of magpie occupancy from 2001 to 2005. In addition, we assessed the importance of the recent
urbanization of the French countryside in determining population dynamics. Overall, our analysis proved that the proportion
of urban areas and recent urbanization in France led to an increase in the probability of magpie occupancy. Unexpectedly,
the species is concomitantly disappearing from the countryside, leading to a rapid change in the distribution of the species.
This study stressed the importance of incorporating detection uncertainty in inference process about spatial dynamics. Overall,
we show how useful it is to account for the dynamic evolution of the landscape in ecological studies. 相似文献
108.
Alana Batista dos Santos Mara Lúcia Albuquerque Pereira Herymá Giovane de Oliveira Silva Gleidson Giordano Pinto de Carvalho Taiala Cristina de Jesus Pereira Leandro Sampaio Oliveira Ribeiro José Augusto Gomes Azevêdo Maria das Graças Conceição Parada Costa Silva Larisse Borges Sousa Leandro Borges Sousa Daiane de Oliveira Alencar 《Tropical animal health and production》2016,48(3):509-515
109.
Thanh Thuy Nguyen Tu Céline Egasse Gérard Bardoux Jean-François Ponge Sylvie Derenne 《Soil biology & biochemistry》2011,43(11):2222-2228
We monitored the carbon isotope composition of bulk leaves and specific long-chain alkanes during a four-year litterbag experiment using 13C-labelled leaves and unlabelled reference leaves of the European beech tree (Fagus sylvatica L.). Whereas the isotope composition of alkanes from 13C-enriched leaves exhibited a marked decrease in 13C-content, the isotope composition of unlabelled reference leaves remained nearly constant. We interpreted this difference as evidence for a microbial contribution to the long-chain alkane pool of the decomposing leaves and related it to the progressive invasion of leaves by soil organisms which was revealed upon microscopic examination. These results suggest that long-chain alkanes may not provide an unaltered record of organic carbon isotope composition in soils and sediments. 相似文献
110.
Le Fresne S Popova M Le Vacon F Carton T 《Journal of agricultural and food chemistry》2011,59(23):12302-12308
The identification of fish species in transformed food products is difficult because the existing methods are not adapted to heat-processed products containing more than one species. Using a common to all vertebrates region of the cytochrome b gene, we have developed a denaturing high-performance liquid chromatography (DHPLC) fingerprinting method, which allowed us to identify most of the species in commercial crab sticks. Whole fish and fillets were used for the creation of a library of referent DHPLC profiles. Crab sticks generated complex DHPLC profiles in which the number of contained fish species can be estimated by the number of major fluorescence peaks. The identity of some of the species was predicted by comparison of the peaks with the referent profiles, and others were identified after collection of the peak fractions, reamplification, and sequencing. DHPLC appears to be a quick and efficient method to analyze the species composition of complex heat-processed fish products. 相似文献