scholarly journals Multi-cohort stand structure as a coarse filter of variation in mixedwood boreal bird communities

2013 ◽  
Vol 89 (03) ◽  
pp. 327-339 ◽  
Author(s):  
Mike V.A. Burrell ◽  
Jay R. Malcolm ◽  
Pierre Drapeau
Keyword(s):  
Structural Variation ◽  
Bird Community ◽  
Bird Communities ◽  
Wildlife Habitat ◽  
The Other ◽  
Stand Age ◽  
Feeding Guilds ◽  
Management Approach ◽  
Weibull Parameters ◽  
Partial Harvest

In targeting mature and over-mature forests for harvesting, management in the boreal forest has resulted in a net loss of older forests that often exhibit complex structural variation and multiple cohorts of trees. Multi-cohort forest management has been proposed as a management approach for these older forests that maintains structural wildlife habitat attributes. At the stand level, the approach relies on various partial harvest techniques to emulate the range of structural variation found in natural boreal landscapes. Here, we examine the extent to which boreal bird communities respond to multi-cohort-related structural variation in boreal mixedwood forests. In particular, we test the utility of parameters of Weibull distributions fitted to stand stem diameter distributions, which have figured prominently in methods to characterize multi-cohort structure, to explain variation in the entire bird community and in various species groupings defined by feeding guilds and forest-type associations. We also compare the explanatory power of the two Weibull parameters against 21 forest structure variables and stand age. In general, Weibull parameters outperformed stand age as a correlate of bird community variation and they were significant explanatory variables for the matrix of all species and for four species groupings, whereas age was significant for only one species grouping. When one or the other Weibull parameter was significant, it also tended to be significant even when variation due to the other was partialled out, supporting the importance not only of forest stature, but also of forest heterogeneity in understanding bird community composition. Thus, we found that multi-cohort-associated structural variation was important in explaining variation among boreal bird communities, supporting the idea of silvicultural approaches that aim at diversifying stand structural characteristics.

scholarly journals The impact of Sosnowsky’s Hogweed on feeding guilds of birds

2021 ◽  
Author(s):  
Emilia Grzędzicka ◽  
Jiří Reif
Keyword(s):  
Negative Impact ◽  
Bird Community ◽  
Plant Invasions ◽  
Bird Communities ◽  
Feeding Guilds ◽  
Guild Structure ◽  
Feeding Guild ◽  
Potential Impact ◽  
Underlying Mechanisms ◽  
The Impact

AbstractPlant invasions alter bird community composition worldwide, but the underlying mechanisms still require exploration. The investigation of feeding guild structure of bird communities can be informative in respect to the potential impact of invasion features on the availability of food for birds. For this purpose, we focused on determining the influence of the invasive Sosnowsky’s Hogweed Heracleum sosnowskyi on the abundance of birds from various feeding guilds. In spring and summer 2019, birds were counted three times on 52 pairs of sites (control + Heracleum) in southern Poland, at various stages of Sosnowsky’s Hogweed development (i.e. sprouting, full growth and flowering, all corresponding to respective bird counts). We have shown that the presence of invader negatively affected the abundance of birds from all feeding guilds. However, a closer examination of the invaded sites uncovered that responses of particular guilds differed in respect to development stages expressed by a set of characteristics of the invader. Ground and herb insectivores were more common on plots with a higher number of the invader, while the abundance of bush and tree insectivores was negatively correlated with hogweeds’ height. Granivores were not affected by the invader’s features, while the abundance of omnivores was negatively related to the number of flowering hogweeds. Besides showing the general negative impact of the invader on different feeding guilds, our research has shown that certain aspects of Sosnowsky’s Hogweed invasion may support or depress occurrence of different birds on invaded plots. Knowledge of these aspects may facilitate our capacity for coping with challenges the invasive plants put in front of bird conservationists.

scholarly journals Temperate forest bird communities associated with a historic mining impact area: do tailing remnant effects modify their structure?

2019 ◽  
Vol 27 (2) ◽  
pp. 94-107
Author(s):  
Katia Lemus ◽  
José Fernando Villaseñor-Gómez ◽  
Francisco Roberto Pineda-Huerta ◽  
Javier Salgado-Ortiz
Keyword(s):  
Toxic Elements ◽  
Anthropogenic Impacts ◽  
Bird Species ◽  
Bird Community ◽  
Control Site ◽  
Potentially Toxic Elements ◽  
Bird Communities ◽  
Feeding Guilds ◽  
Mining District ◽  
Ecological Processes

AbstractBirds contribute to the stability of ecosystems and represent a tool used to evaluate a variety of anthropogenic impacts. The area known as El Oro-Tlalpujahua Mining District in central Mexico was subjected to significant environmental impacts as a result of ore extraction, including profound habitat transformations, landscape changes, and the accumulation of potentially toxic elements in their tailings (favoring its bioavailability and dispersion). After more than 60 years without extractive activities, there is no knowledge on extant remaining impacts on biological communities. Assuming the presence of negative impacts on birds, we compared the composition and abundance of bird communities in two locations, representing a site without exposure to tailings (S1) and another one with tailings deposition (S2). From June 2014 to June 2015, we recorded 2828 individuals of 108 avian species in 369 point counts (S1 = 91, S2 = 95). The Chao1 indicator suggested we recorded 96% of the species present. We found a high similarity in the general composition and abundance of bird species between communities (> 85%). However, there were significant differences in the abundances of 18 species (9 of them higher in the control site); these differences might result from differential effects of potentially toxic elements on functional groups (such as feeding guilds), resource availability, as well as other factors not accounted for. Historically, mining activities in the area generated significant changes in the structure and composition of the forest, and disrupted ecological processes. Despite the fact that current conditions appear favorable to the relative stability of the bird community, specific physiological effects on some species of birds sixty years after the cessation of mineral extraction could occur. Further studies on physiological performance and the effects of potentially toxic elements on local birds could unveil unknown effects at the individual level.

scholarly journals Temporal dynamic of the phylogenetic diversity of the bird community of agricultural lands in Ukrainian steppe drylands

2020 ◽  
Vol 28 (1) ◽  
pp. 34-40
Author(s):  
A. I. Koshelev ◽  
O. Y. Pakhomov ◽  
O. M. Kunakh ◽  
V. A. Koshelev ◽  
M. P. Fedushko
Keyword(s):  
Phylogenetic Diversity ◽  
Bird Community ◽  
Bird Communities ◽  
The Other ◽  
Alauda Arvensis ◽  
Coturnix Coturnix ◽  
The One ◽  
Burhinus Oedicnemus ◽  
Corvus Monedula ◽  
Over Time

This study discussed the importance of the phylogenetic components in the structure of bird communities of anthropogenically transformed ecosystems. The investigation was conducted in the landscapes of the south and south-east of Ukraine in the nesting seasons 1988–2018. The bird community in the agricultural landscape was found to be presented by 10 species. The number of species was closely correlated with its phylogenetic analogue – Faith’s index. Both indices were stationary over time, as they do not show a statistically significant time trend. The two axes were extracted as a result of the DPCOA procedure and the permutation test showed their statistical significance. The axis 1 was the most sensitive to the opposite dynamics of the abundance of Coturnix coturnix and Burhinus oedicnemus on the one hand and Alauda arvensis and Melanocorypha calandra on the other. The axis 2 is the most sensitive to the opposite dynamics of Corvus monedula and Melanocorypha calandra on the one hand and Coturnix coturnix and Motacilla flava on the other. Based on phylogenetic diversity, the years can be clustered with the extraction of four relatively homogeneous phylogenetic structures of bird communities. The indicator of the initial period of dynamics (1988–1992) was Burhinus oedicnemus. Sowing or mechanical weeding may be considered as a major factor of nest destruction of Burhinus oedicnemus. The decreasing of the abundance of the trophic recourses because of agricultural activity may have caused the monotonous negative trend over time of the Burhinus oedicnemus populations. The period 1993–2003 was a transitional one, for which there were no clear indicators, as a characteristic feature of this period was the processes of bird community restructuring. The period 2004–2013 was characterized by the loss of Burhinus oedicnemus from the community and a sharp increase in the abundance of Corvus monedula. These species are distinguished by their phylogenetic specificity and are located on the periphery relative to the phylogenetic core of the community. There was growing importance in the community of such species as Alauda arvensis, Anthus campestris, and Melanocorypha calandra between 2014 and 2018. Our results also confirm the assumption that phylogenetic overdispersion is an important requirement for the stability of the bird community in anthropogenically transformed landscapes.

scholarly journals A comparison of bird communities in the anthropogenic and natural-tree fall gaps of a reduced-impact logged subtropical forest in Bolivia

2008 ◽  
Vol 18 (2) ◽  
pp. 129-143 ◽  
Author(s):  
Adam Felton ◽  
Jeff T. Wood ◽  
Annika M. Felton ◽  
David B. Lindenmayer ◽  
Bennett A. Hennessey
Keyword(s):  
Community Composition ◽  
Tree Species ◽  
Bird Community ◽  
Subtropical Forest ◽  
Bird Communities ◽  
The Other ◽  
Sensitive Species ◽  
Significant Difference ◽  
Logged Forest ◽  
Reduced Impact Logging

AbstractWe studied bird community composition and abundance within four vegetation and disturbance categories located within selectively logged and unlogged forest in a Bolivian subtropical lowland forestry concession. The logged forest was subject to reduced-impact logging between 1 and 4 years prior to our study. The four categories were: 1) ‘gap’ points possessing natural or anthropogenic tree-fall gaps; 2) ‘target’ points with one of five commercial tree species of harvestable size; 3) ‘future’ points possessing a commercial tree below harvestable size and 4) ‘non-target’ points not possessing harvestable tree species. The bird community composition of logging gaps significantly differed from that found within natural tree-fall gaps in the unlogged forest P< 0.05. Species richness was higher in natural tree-fall gaps than in anthropogenic gaps. Furthermore, a higher proportion of disturbance sensitive species were associated with natural-tree fall gaps, whereas a higher proportion of disturbance tolerant species were associated with anthropogenic gaps. No significant difference was detected in the bird community composition for the other three vegetation categories surveyed. We discuss the conservation and silvicultural repercussions of these results.

scholarly journals The Bird Assemblage of the Darwin Region (Australia): What Is the Effect of Twenty Years of Increasing Urbanisation?

Diversity ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 294
Author(s):  
Sarah E. Fischer ◽  
Andrew C. Edwards ◽  
Patrice Weber ◽  
Stephen T. Garnett ◽  
Timothy G. Whiteside
Keyword(s):  
Urban Development ◽  
Bird Community ◽  
Feeding Guilds ◽  
Australian Birds ◽  
Bird Survey ◽  
Species Analysis ◽  
Community Data ◽  
Bird Assemblage ◽  
Significant Change ◽  
The Difference

There has been considerable urban development in the Darwin region over the last twenty years; as for most fauna in Australia since colonisation, the potential effects to the bird assemblage were expected to be disastrous. To provide a broad overview of changes, bird survey data from 1998 and 2018 were extracted from BirdLife Australia’s ‘Atlas of Australian Birds’ database. A total of 165 species were categorised into primary food source feeding guilds and levels of food specialisation. This was integrated into ArcGIS along with land use change mapping from 1998 and 2018 to investigate its impact on bird assemblages. There was no significant change in overall species numbers when all sites were analysed. However, when sites were separated into those with increased urbanisation or decreased greenspace, several sites showed a significant change in the number of species. For the majority of species, analysis of primary food types found no difference in the proportion of species within the assemblages between 1998 and 2018, regardless of the level of urbanisation or greenspace; the exception being those species that primarily feed on insects, where the difference was just significant. An analysis using bird community data sorted into levels of food specialisation also found no difference between 1998 and 2018 despite habitat changes. These findings suggest that although there has been considerable urban development in the Darwin region, bird communities are remaining relatively stable.

scholarly journals Two case studies on structural variation in multilingual settings

2020 ◽  
Vol 5 (1) ◽  
pp. 750
Author(s):  
Ariana Bancu
Keyword(s):  
Case Studies ◽  
Structural Properties ◽  
Language Contact ◽  
Structural Variation ◽  
Mixed Effects ◽  
The Other ◽  
Trajectories Of Change ◽  
Induced Variation ◽  
Shed Light

In this article, I report on two analyses of variation in Transylvanian Saxon (TrSax), an endangered Germanic language in contact with German and Romanian, used in settings predictive of structural influences among languages. My goals are to document the structural properties of the target variables and to evaluate if processes of language contact have an effect on synchronic variation in TrSax. I identified two areas of TrSax that display variation at the morphosyntactic level, and in each case one of the variants has a corresponding structure in German, while the other variant has a corresponding structure in Romanian. To tease apart contact-induced variation from internally motivated variation, I compare data from multilingual speakers with different linguistic profiles and assess the effect of sociolinguistic factors on variation through mixed effects analyses. Variation that patterns similarly across these two groups can provide a clearer account of the structure of TrSax, while differences between the groups can shed light on trajectories of change in TrSax. Furthermore, results of this study have implications for borrowing hierarchies in language contact.

scholarly journals Redewiedergabe in Online-Pressetexten – kontrastiv

2019 ◽  
Vol 47 (1) ◽  
pp. 137-176
Author(s):  
Anneliese Pitz ◽  
Kåre Solfjeld
Keyword(s):  
Structural Variation ◽  
The Other ◽  
Reported Speech ◽  
Direct Speech ◽  
Structural Variety ◽  
Other Hand

Abstract This article looks into what structures are used to report longer sequences of speech in German, English and Norwegian online press media. In German the subjunctive is used to signal speech report, and so there is a wider range of structural possibilities in German than in English and Norwegian, which have no counterparts to the subjunctive. The study is corpus-based and identifies and compares recurring patterns in reported sequences in the three languages, as well as type and range of verbs of utterance. The concept of syntactical integration of the reported speech and markers of report (Leistner 2016) is central. The study shows that also in the two languages without subjunctive the source of a text part is in general clear: The reader knows whether the text part stems from the journalist or from a reported person. The structural variety in German is outweighed by long sequences of direct speech in English and Norwegian, unambiguously identified as report. This seems to entail a stronger obligation to the wording of the original in English and Norwegian than in German, which on the other hand displays a stronger structural variation.

scholarly journals Spatial and temporal patterns of bird species diversity in the Pantanal of Mato Grosso, Brazil: implications for conservation

2006 ◽  
Vol 66 (2a) ◽  
pp. 393-404 ◽  
Author(s):  
J. E. C. Figueira ◽  
R. Cintra ◽  
L. R. Viana ◽  
C. Yamashita
Keyword(s):  
Human Impacts ◽  
Bird Species ◽  
Bird Community ◽  
The Other ◽  
Resident Species ◽  
Spatial And Temporal Patterns ◽  
Mato Grosso ◽  
Bird Survey ◽  
Bird Species Diversity ◽  
Habitat Generalists

Analysis of a three-year bird survey in the pantanal of Poconé revealed that most of the resident and seasonal birds are habitat generalists, using two or more habitats. In this study, previously sampled habitats were ranked in relation to species richness and stability (as measured by the ratio of seasonal to resident species). In all, nine habitats were grouped into three categories; results are as follows: 1) forests: more species-rich and more stable; 2) cerrado: intermediate levels; and 3) aquatic: less species-rich and less stable. The number of seasonal species remained relatively constant in forests throughout the year, while increasing in the other habitats during the dry season. The abundance of resident species seems to be related to species use of multiple habitats. Although many species were found to be habitat generalists, we discuss possible consequences of habitat loss and other human impacts on efforts to conserve this important bird community.

Contrasting cybersecurity implementation frameworks (CIF) from three countries

2019 ◽  
Vol 27 (3) ◽  
pp. 373-392
Author(s):  
Adenekan Dedeke ◽  
Katherine Masterson
Keyword(s):  
Risk Management ◽  
Design Methodology ◽  
Document Analysis ◽  
Decision Makers ◽  
The Other ◽  
Management Approach ◽  
Content Type ◽  
Assessment Matrix ◽  
Comprehensive Framework ◽  
Country Specific

Purpose This paper aims to explore the evolution of a trend in which countries are developing or adopting cybersecurity implementation frameworks that are intended to be used nationally. This paper contrasts the cybersecurity frameworks that have been developed in three countries, namely, Australia, UK and USA. Design/methodology/approach The paper uses literature review and qualitative document analysis for the study. The paper developed and used an assessment matrix as its coding protocol. The contents of the three cybersecurity frameworks were then scored to capture the degree to which they covered the themes/items of the cybersecurity assessment matrix. Findings The analysis found that the three cybersecurity frameworks are oriented toward the risk management approach. However, the frameworks also had notable differences with regard to the security domains that they cover. For example, one of the frameworks did not offer guidelines with regard to what to do to respond to attacks or to plan for recovery. Originality/value The results of this study are beneficial to policymakers in the three countries targeted, as they are able to gain insights about how their cybersecurity frameworks compares to those of the other two countries. Such knowledge would be useful as decision-makers take steps to improve their existing frameworks. The results of this study are also beneficial to executives who have branches in all three countries. In such cases, security professionals could deploy the most comprehensive framework across all three countries and then extend the deployment in each location to meet country-specific requirements.

Cutting management and alfalfa stand age effects on organically grown corn grain yield and soil N availability

2017 ◽  
Vol 34 (2) ◽  
pp. 144-154 ◽  
Author(s):  
Adria L. Fernandez ◽  
Karina P. Fabrizzi ◽  
Nicole E. Tautges ◽  
John A. Lamb ◽  
Craig C. Sheaffer
Keyword(s):  
The Other ◽  
Stand Age ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Mineral N ◽  
No Removal ◽  
Soil C ◽  
Biomass Removal ◽  
Potentially Mineralizable N ◽  
Corn Grain

AbstractAlfalfa is recommended as a rotational crop in corn production, due to its ability to contribute to soil nitrogen (N) and carbon (C) stocks through atmospheric N2fixation and above- and belowground biomass production. However, there is little information on how alfalfa management practices affect contributions to soil and subsequent corn crop yields, and research has not been targeted to organic systems. A study was conducted to determine the effects of alfalfa stand age, cutting frequency and biomass removal on soil C and N status and corn yields at three organically managed Minnesota locations. In one experiment, five cutting treatments were applied in nine environments: two, three and four cuts with biomass removal; three cuts with biomass remaining in place; and a no-cut control. In the other experiment, corn was planted following 1-, 2-, 3- or 4-year-old alfalfa stands and a no-alfalfa control. Yield was measured in the subsequent corn crop. In the cutting experiment, the two- and three-cut treatments with biomass removal reduced soil mineral N by 12.6 and 11.5%, respectively, compared with the control. Potentially mineralizable N (PMN) was not generally affected by cutting treatments. The three-cut no-removal increased potentially mineralizable C by 17% compared with the other treatments, but lowered soil total C in two environments, suggesting a priming effect in which addition of alfalfa biomass stimulated microbial mineralization of native soil C. Although both yields and soil mineral N tended to be higher in treatments where biomass remained in place, this advantage was small and inconsistent, indicating that farmers need not forgo hay harvest to obtain the rotational benefits of an alfalfa stand. The lack of overall correlation between corn grain yields and mineral and potentially mineralizable N suggests that alfalfa N contribution was not the driver of the yield increase in the no-removal treatments. Alfalfa stand age had inconsistent effects on fall-incorporated N and soil N and C parameters. Beyond the first year, increased alfalfa stand age did not increase soil mineral N or PMN. However, corn yield increased following older stands. Yields were 29, 77 and 90% higher following first-, second- and third-year alfalfa stands than the no-alfalfa control, respectively. This indicates that alfalfa may benefit succeeding corn through mechanisms other than N contribution, potentially including P solubilization and weed suppression. These effects have been less studied than N credits, but are of high value in organic cropping systems.

Sign in / Sign up

Export Citation Format

Share Document