bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pastoral and woodcutting activities drive Cedrus atlantica Mediterranean forest structure in the Moroccan Middle Atlas
Authors: Coudel Marc , Aubert Pierre‐Marie , Aderghal Mohammed , Hély Christelle 
Published: May 2016

AbstractHuman activities are historical ecological drivers, and we need to better understand their effects on ecosystems. In particular, they have been very important in the shaping of the Mediterranean biodiversity hotspot. Researchers and managers nonetheless lack knowledge concerning the impacts of their combinations and their current intensity on the structure of forest ecosystems of the southern part of the Mediterranean basin. In this study, we have develped a new methodology in order to understand the impacts of combined pastoral and woodcutting activities on the forest structure of the still ill‐described but ecologically and economically important Moroccan Middle Atlas cedar forests. In a 40 000 ha forest, we chose 103 sites and sampled human activities through proxies and forest structures through circumference and vertical structures. A typology of sites yielded four human activity types: dominant pastoral activities, dominant oak cutting or cedar cutting activities, and an intermediate mid‐disturbance type. This typology did not depend on altitude or substrate, confirming that the ecosystem structures linked to the different types depend more on human activities than on main environmental parameters. Pastoral activities modified forests the most, converting them to parklands with reduced canopies and low dynamics but high tree maturation. Woodcutting activities induced gap dynamics, favoring Cedrus atlantica in favorable environmental conditions and Quercus ilex otherwise, while they affected vertical structure depending on the local environment and competition for light and soil resources. Moderately disturbed stands showed forest maturation with low competition for light. Unlike previous studies, we found no evidence of a general degradation of cedar forests due to local human activities. However, cedar logging has reduced standing basal area regionally and one third of the sites may have vulnerable cedar populations due to pastoral activities and to unfavorable environmental conditions. These results can direct future research and management needs for a better protection of Mediterranean forests and parklands and their biodiversity, although to be effective such efforts must also partner with sociogeographical studies.
Carbon sources and trophic relationships of ice seals during recent environmental shifts in the Bering Sea
Authors: Wang Shiway W. , Springer Alan M. , Budge Suzanne M. , Horstmann Lara , Quakenbush Lori T. , Wooller Matthew J. 
Published: May 2016

AbstractDramatic multiyear fluctuations in water temperature and seasonal sea ice extent and duration across the Bering–Chukchi continental shelf have occurred in this century, raising a pressing ecological question: Do such environmental changes alter marine production processes linking primary producers to upper trophic‐level predators? We examined this question by comparing the blubber fatty acid (FA) composition and stable carbon isotope ratios of individual FA (δ13CFA) of adult ringed seals (Pusa hispida), bearded seals (Erignathus barbatus), spotted seals (Phoca largha), and ribbon seals (Histriophoca fasciata), collectively known as “ice seals,” sampled during an anomalously warm, low sea ice period in 2002–2005 in the Bering Sea and a subsequent cold, high sea ice period in 2007–2010. δ13CFAvalues, used to estimate the contribution to seals of carbon derived from sea ice algae (sympagic production) relative to that derived from water column phytoplankton (pelagic production), indicated that during the cold period, sympagic production accounted for 62–80% of the FA in the blubber of bearded seals, 51–62% in spotted seals, and 21–60% in ringed seals. Moreover, the δ13CFAvalues of bearded seals indicated a greater incorporation of sympagic FAs during the cold period than the warm period. This result provides the first empirical evidence of an ecosystem‐scale effect of a putative change in sympagic production in the Western Arctic. The FA composition of ice seals showed clear evidence of resource partitioning among ringed, bearded, and spotted seals, and little niche separation between spotted and ribbon seals, which is consistent with previous studies. Despite interannual variability, the FA composition of ringed and bearded seals showed little evidence of differences in diet between the warm and cold periods. The findings that sympagic production contributes significantly to food webs supporting ice seals, and that the contribution apparently is less in warm years with low sea ice, raise an important concern: Will the projected warming and continuing loss of seasonal sea ice in the Arctic, and the associated decline of organic matter input from sympagic production, be compensated for by pelagic production to satisfy both pelagic and benthic carbon and energy needs?
Characterizing forest structure variations across an intact tropical peat dome using field samplings and airborne LiDAR
Authors: Nguyen Ha T. , Hutyra Lucy R. , Hardiman Brady S. , Raciti Steve M. 
Published: May 2016

AbstractTropical peat swamp forests (PSF) are one of the most carbon dense ecosystems on the globe and are experiencing substantial natural and anthropogenic disturbances. In this study, we combined direct field sampling and airborne LiDAR to empirically quantify forest structure and aboveground live biomass (AGB) across a large, intact tropical peat dome in Northwestern Borneo. Moving up a 4 m elevational gradient, we observed increasing stem density but decreasing canopy height, crown area, and crown roughness. These findings were consistent with hypotheses that nutrient and hydrological dynamics co‐influence forest structure and stature of the canopy individuals, leading to reduced productivity towards the dome interior. Gap frequency as a function of gap size followed a power law distribution with a shape factor (λ) of 1.76 ± 0.06. Ground‐based and dome‐wide estimates of AGB were 217.7 ± 28.3 Mg C/ha and 222.4 ± 24.4 Mg C/ha, respectively, which were higher than previously reported AGB for PSF and tropical forests in general. However, dome‐wide AGB estimates were based on height statistics, and we found the coefficient of variation on canopy height was only 0.08, three times less than stem diameter measurements, suggesting LiDAR height metrics may not be a robust predictor of AGB in tall tropical forests with dense canopies. Our structural characterization of this ecosystem advances the understanding of the ecology of intact tropical peat domes and factors that influence biomass density and landscape‐scale spatial variation. This ecological understanding is essential to improve estimates of forest carbon density and its spatial distribution in PSF and to effectively model the effects of disturbance and deforestation in these carbon dense ecosystems.
Placing invasive species management in a spatiotemporal context
Authors: Baker Christopher M. , Bode Michael 
Published: May 2016

AbstractInvasive species are a worldwide issue, both ecologically and economically. A large body of work focuses on various aspects of invasive species control, including how to allocate control efforts to eradicate an invasive population as cost effectively as possible. There are a diverse range of invasive species management problems, and past mathematical analyses generally focus on isolated examples, making it hard to identify and understand parallels between the different contexts. In this study, we use a single spatiotemporal model to tackle the problem of allocating control effort for invasive species when suppressing an island invasive species, and for long‐term spatial suppression projects. Using feral cat suppression as an illustrative example, we identify the optimal resource allocation for island and mainland suppression projects. Our results demonstrate how using a single model to solve different problems reveals similar characteristics of the solutions in different scenarios. As well as illustrating the insights offered by linking problems through a spatiotemporal model, we also derive novel and practically applicable results for our case studies. For temporal suppression projects on islands, we find that lengthy projects are more cost effective and that rapid control projects are only economically cost effective when population growth rates are high or diminishing returns on control effort are low. When suppressing invasive species around conservation assets (e.g., national parks or exclusion fences), we find that the size of buffer zones should depend on the ratio of the species growth and spread rate.
Pathogen exposure varies widely among sympatric populations of wild and domestic felids across the United States
Authors: Carver Scott , Bevins Sarah N. , Lappin Michael R. , Boydston Erin E. , Lyren Lisa M. , Alldredge Mathew , Logan Kenneth A. , Sweanor Linda L. , Riley Seth P. D. , Serieys Laurel E. K. , Fisher Robert N. , Vickers T. Winston , Boyce Walter , McBride Roy , Cunningham Mark C. , Jennings Megan , Lewis Jesse , Lunn Tamika , Crooks Kevin R. , VandeWoude Sue 
Published: May 2016

AbstractUnderstanding how landscape, host, and pathogen traits contribute to disease exposure requires systematic evaluations of pathogens within and among host species and geographic regions. The relative importance of these attributes is critical for management of wildlife and mitigating domestic animal and human disease, particularly given rapid ecological changes, such as urbanization. We screened >1000 samples from sympatric populations of puma (Pumaconcolor), bobcat (Lynxrufus), and domestic cat (Felis catus) across urban gradients in six sites, representing three regions, in North America for exposure to a representative suite of bacterial, protozoal, and viral pathogens (Bartonellasp.,Toxoplasma gondii, feline herpesvirus‐1, feline panleukopenea virus, feline calicivirus, and feline immunodeficiency virus). We evaluated prevalence within each species, and examined host trait and land cover determinants of exposure; providing an unprecedented analysis of factors relating to potential for infections in domesticated and wild felids. Prevalence differed among host species (highest for puma and lowest for domestic cat) and was greater for indirectly transmitted pathogens. Sex was inconsistently predictive of exposure to directly transmitted pathogens only, and age infrequently predictive of both direct and indirectly transmitted pathogens. Determinants of pathogen exposure were widely divergent between the wild felid species. For puma, suburban land use predicted increased exposure toBartonellasp. in southern California, andFHV‐1 exposure increased near urban edges in Florida. This may suggest interspecific transmission with domestic cats via flea vectors (California) and direct contact (Florida) around urban boundaries. Bobcats captured near urban areas had increased exposure toT. gondiiin Florida, suggesting an urban source of prey. Bobcats captured near urban areas in Colorado and Florida had higherFIVexposure, possibly suggesting increased intraspecific interactions through pile‐up of home ranges. Beyond these regional and pathogen specific relationships, proximity to the wildland–urban interface did not generally increase the probability of disease exposure in wild or domestic felids, emphasizing the importance of local ecological determinants. Indeed, pathogen exposure was often negatively associated with the wildland–urban interface for all felids. Our analyses suggest cross‐species pathogen transmission events around this interface may be infrequent, but followed by self‐sustaining propagation within the new host species.
Maintaining animal assemblages through single‐species management: the case of threatened caribou in boreal forest
Authors: Bichet Orphé , Dupuch Angélique , Hébert Christian , Le Borgne Hélène , Fortin Daniel 
Published: May 2016

AbstractWith the intensification of human activities, preserving animal populations is a contemporary challenge of critical importance. In this context, the umbrella species concept is appealing because preserving a single species should result in the protection of multiple co‐occurring species. Practitioners, though, face the task of having to find suitable umbrellas to develop single‐species management guidelines. In North America, boreal forests must be managed to facilitate the recovery of the threatened boreal caribou (Rangifer tarandus). Yet, the effect of caribou conservation on co‐occurring animal species remains poorly documented. We tested if boreal caribou can constitute an effective umbrella for boreal fauna. Birds, small mammals, and insects were sampled along gradients of post‐harvest and post‐fire forest succession. Predictive models of occupancy were developed from the responses of 95 species to characteristics of forest stands and their surroundings. We then assessed the similarity of species occupancy expected between simulated harvested landscapes and a 90 000‐km2 uncut landscape. Managed landscapes were simulated based on three levels of disturbance, two timber‐harvest rotation cycles, and dispersed or aggregated cut‐blocks. We found that management guidelines that were more likely to maintain caribou populations should also better preserve animal assemblages. Relative to fragmentation or harvest cycle, we detected a stronger effect of habitat loss on species assemblages. Disturbing 22%, 35%, and 45% of the landscape should result, respectively, in 80%, 60%, and 40% probability for caribou populations to be sustainable; in turn, this should result in regional species assemblages with Jaccard similarity indices of 0.86, 0.79, and 0.74, respectively, relative to the uncut landscape. Our study thus demonstrates the value of single‐species management for animal conservation. Our quantitative approach allows for the evaluation of management guidelines prior to implementation, thereby providing a tool for establishing suitable compromises between economic and environmental sustainability of human activities.
Chronic nitrogen deposition alters tree allometric relationships: implications for biomass production and carbon storage
Authors: Ibáñez Inés , Zak Donald R. , Burton Andrew J. , Pregitzer Kurt S. 
Published: May 2016

AbstractAs increasing levels of nitrogen (N) deposition impact many terrestrial ecosystems, understanding the potential effects of higher N availability is critical for forecasting tree carbon allocation patterns and thus future forest productivity. Most regional estimates of forest biomass apply allometric equations, with parameters estimated from a limited number of studies, to forest inventory data (i.e., tree diameter). However, most of these allometric equations cannot account for potential effects of increased N availability on biomass allocation patterns. Using 18 yr of tree diameter, height, and mortality data collected for a dominant tree species (Acer saccharum) in an atmospheric N deposition experiment, we evaluated how greater N availability affects allometric relationships in this species. After taking into account site and individual variability, our results reveal significant differences in allometric parameters between ambient and experimental N deposition treatments. Large trees under experimental N deposition reached greater heights at a given diameter; moreover, their estimated maximum height (mean ± standard deviation: 33.7 ± 0.38 m) was significantly higher than that estimated under the ambient condition (31.3 ± 0.31 m). Within small tree sizes (5–10 cm diameter) there was greater mortality under experimental N deposition, whereas the relative growth rates of small trees were greater under experimental N deposition. Calculations of stemwood biomass using our parameter estimates for the diameter–height relationship indicated the potential for significant biases in these estimates (~2.5%), with under predictions of stemwood biomass averaging 4 Mg/ha lower if ambient parameters were to be used to estimate stem biomass of trees in the experimental N deposition treatment. As atmospheric N deposition continues to increase into the future, ignoring changes in tree allometry will contribute to the uncertainty associated with aboveground carbon storage estimates across a forest with a large geographic distribution in eastern North America.
Environmental heterogeneity has a weak effect on diversity during community assembly in tallgrass prairie
Authors: Baer Sara G. , Blair John M. , Collins Scott L. 
Published: May 2016

Abstract
Understanding what constrains the persistence of species in communities is at the heart of community assembly theory and its application to conserving and enhancing biodiversity. The “environmental heterogeneity hypothesis” predicts greater species coexistence in habitats with greater resource variability. In the context of community assembly, environmental heterogeneity may influence the variety and strength of abiotic conditions and competitive interactions (environmental filters) to affect the relative abundance of species and biodiversity. We manipulated key resources that influence plant diversity in tallgrass prairie (i.e., soil depth and nitrogen availability) to increase environmental heterogeneity prior to sowing native prairie species into a former agricultural field. We compared variability in nutrient availability, aboveground annual net primary productivity (ANPP), and the composition of species between replicate plots containing soil heterogeneity manipulations and plots with no resource manipulations (n = 4 per treatment) during the first 15 yr of community assembly as a test of the “environmental heterogeneity hypothesis.” The manipulations increased environmental heterogeneity, measured as the coefficient of variation in NO3‐N availability and ANPP. Plant diversity, however, was similar and decayed exponentially and indiscriminately over time between the heterogeneity treatments. Species richness declined linearly over time in both heterogeneity treatments, but richness was higher in the more heterogeneous soil 2 yr following a second propagule addition 8 yr after the initial sowing. As a result, there was a lower rate of species loss over time in the more heterogeneous soil (0.60 species yr−1) relative to the control soil (0.96 species yr−1). Communities in each treatment exhibited strong convergence over time resulting from a shift in dominant species across all treatments and a gradual increase in the clonal C4 grass, Andropogon gerardii. We attribute the weak effect of heterogeneity on diversity to increasing dominance of a clonal species, which decreased the scale of soil treatments relative to plant size, dispersal limitation, and absence of a key driver (grazing) known to increase plant diversity under a frequent fire regime. Thus, steering community assembly to attain high biodiversity may depend more on manipulating processes that reduce dominance and facilitate the arrival of new species than promoting environmental heterogeneity.
Identification of migratory bird flyways in North America using community detection on biological networks
Authors: Buhnerkempe Michael G. , Webb Colleen T. , Merton Andrew A. , Buhnerkempe John E. , Givens Geof H. , Miller Ryan S. , Hoeting Jennifer A. 
Published: May 2016

AbstractMigratory behavior of waterfowl populations in North America has traditionally been broadly characterized by four north–south flyways, and these flyways have been central to the management of waterfowl populations for more than 80 yr. However, previous flyway characterizations are not easily updated with current bird movement data and fail to provide assessments of the importance of specific geographical regions to the identification of flyways. Here, we developed a network model of migratory movement for four waterfowl species, Mallard (Anas platyrhnchos), Northern Pintail (A. acuta), American Green‐winged Teal (A. carolinensis), and Canada Goose (Branta canadensis), in North America, using bird band and recovery data. We then identified migratory flyways using a community detection algorithm and characterized the importance of smaller geographic regions in identifying flyways using a novel metric, the consolidation factor. We identified four main flyways for Mallards, Northern Pintails, and American Green‐winged Teal, with the flyway identification in Canada Geese exhibiting higher complexity. For Mallards, flyways were relatively consistent through time. However, consolidation factors revealed that for Mallards and Green‐winged Teal, the presumptive Mississippi flyway was potentially a zone of high mixing between other flyways. Our results demonstrate that the network approach provides a robust method for flyway identification that is widely applicable given the relatively minimal data requirements and is easily updated with future movement data to reflect changes in flyway definitions and management goals.
Periodontal Wound Healing by Transplantation of Jaw Bone Marrow‐Derived Mesenchymal Stem Cells in Chitosan/Anorganic Bovine Bone Carrier Into One‐Wall Infrabony Defects in Beagles
Authors: Zang Shengqi , Jin Lei , Kang Shuai , Hu Xin , Wang Meng , Wang Jinjin , Chen Bo , Peng Bo , Wang Qintao 
Published: May 2016

Background: This study aims to evaluate the performance of chitosan/anorganic bovine bone (C/ABB) scaffold seeded with human jaw bone marrow‐derived mesenchymal stem cells (hJBMMSCs) in supporting the healing/repair of 1‐wall critical‐size periodontal defects.Methods: Physical properties of the C/ABB scaffold were compared with those of the chitosan scaffold. hJBMMSCs were obtained from healthy human alveolar bone during the extraction of third molar impacted teeth. One‐wall (7 × 4 mm) infrabony defects were surgically created at the bilateral mandibular third premolars and first molars in six beagles. The defects were randomly assigned to six groups and implanted with different scaffolds: 1) chitosan (C) scaffold; 2) C scaffold with hJBMMSCs (C + cell); 3) C/ABB scaffold (C/ABB); 4) C/ABB scaffold with hJBMMSCs (C/ABB + cell); 5) ABB scaffold (ABB); and 6) open flap debridement (control). The animals were euthanized 8 weeks after surgery for histologic analysis.Results: The C/ABB scaffold had a porous structure and increased compressive strength. Both C/ABB and C/ABB + cell exhibited the newly formed cellular mixed‐fiber cementum, woven/lamellar bone, and periodontal ligament. Cementum formation was significantly greater in group C/ABB + cell than in group C/ABB (2.64 ± 0.50 mm versus 0.91 ± 0.55 mm, P <0.05). For new bone (NB) height, group C/ABB + cell and C/ABB showed mean ± SD values of 2.83 ± 0.29 mm and 2.65 ± 0.52 mm and for NB area 8.89 ± 1.65 mm and 8.73 ± 1.94 mm2, respectively. For NB (height and area), there was no significant difference between the two groups.Conclusions: The combination of hJBMMSCs and C/ABB scaffolds could promote periodontal repair. Future studies are expected to further optimize the combination and lead to an ideal periodontal regeneration.