Aim: Although the negative effects of habitat fragmentation have been widely documented at the landscape scale, much less is known about its impacts on species distributions at the biogeographical ...scale. We hypothesize that fragmentation influences the large-scale distribution of area- and edge-sensitive species by limiting their occurrence in regions with fragmented habitats, despite otherwise favourable environmental conditions. We test this hypothesis by assessing the interplay of climate and landscape factors influencing the distribution of the calandra lark, a grassland specialist that is highly sensitive to habitat fragmentation. Location: Iberia Peninsula, Europe. Methods: Ecological niche modelling was used to investigate the relative influence of climate/topography, landscape fragmentation and spatial structure on calandra lark distribution. Modelling assumed explicitly a hierarchically structured effect among explanatory variables, with climate/topography operating at broader spatial scales than landscape variables. An eigenvector-based spatial filtering approach was used to cancel bias introduced by spatial autocorrelation. The information theoretic approach was used in model selection, and variation partitioning was used to isolate the unique and shared effects of sets of explanatory variables. Results: Climate and topography were the most influential variables shaping the distribution of calandra lark, but incorporating landscape metrics contributed significantly to model improvement. The probability of calandra lark occurrence increased with total habitat area and declined with the number of patches and edge density. Variation partitioning showed a strong overlap between variation explained by climate/topography and landscape variables. After accounting for spatial structure in species distribution, the explanatory power of environmental variables remained largely unchanged. Main conclusions: We have shown here that landscape fragmentation can influence species distributions at the biogeographical scale. Incorporating fragmentation metrics into large-scale ecological niche models may contribute for a better understanding of mechanism driving species distributions and for improving predictive modelling of range shifts associated with land use and climate changes.
Introduced alien species are associated with lower taxonomic, functional and phylogenetic diversity of native communities and negative impacts on ecosystem functioning. This is particularly evident ...in habitats where human disturbance may favour alien species, posing an additional stressor on native communities. Following the community resistance hypothesis (higher diversity promotes higher resistance to invasion), we predicted: 1) higher taxonomic, functional and phylogenetic diversity (TD, FD and PD respectively) in non‐invaded bird communities (i.e. no alien bird species); and 2) higher diversity and resistance to invasion in less human‐disturbed areas. We surveyed bird communities in a modified Mediterranean landscape subject to varying levels of human disturbance. We tested whether TD, FD and PD were significantly different between non‐invaded and invaded bird communities, and assessed the effect of land classes (forest, agriculture, urban), landscape composition and heterogeneity on these metrics. We found that non‐invaded communities retained higher TD and FD, but not PD, than invaded communities. Alien birds occupied marginal niches in invaded communities, and did not fully compensate for the taxonomic and functional diversity loss caused by the absence of native species. These results were consistent across different land classes, suggesting weak environmental filtering of communities. Generally, less human‐modified and more heterogeneous areas supported higher TD regardless of the presence of alien species. FD and PD of invaded communities decreased with increases in human‐modified areas, whereas non‐invaded communities were not affected. Our results suggest that even within a human‐modified landscape, invaded community diversity is more affected by, and thus has a lower resilience to, disturbance. Restoring and protecting natural habitats within human‐modified landscapes is likely to increase the resilience of native species.
Human‐induced globalization of insular herpetofaunas Capinha, César; Marcolin, Fabio; Reino, Luís ...
Global ecology and biogeography,
August 2020, 2020-08-00, 20200801, Letnik:
29, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Aim
The aim was to document the impact of the globalization of human activity on the biodiversity and biogeographical patterns of reptilian and amphibian faunas across islands worldwide.
Location
...Islands worldwide.
Time period
From the 15th century to the present time.
Major taxa studied
Reptiles and amphibians.
Methods
We compiled lists of the reptilian and amphibian species that occurred on islands before the 15th century and of those that occur currently. For each species group, we calculated differences in species richness and in compositional similarities among islands, between the two periods. Regression models were used: (a) to associate the observed differences with spatial patterns of geographical, climatic, biotic and human factors; and (b) to quantify changes in the relative importance of non‐human factors in explaining the spatial patterns of species richness and compositional similarity.
Results
The richness of reptile and amphibian species increased consistently across islands worldwide. Hotspots of increase were detected in the Caribbean and the Indian Ocean. The composition of species assemblages was substantially homogenized; this was particularly true for amphibians within the Caribbean Sea and for reptiles within the Caribbean Sea and Indian Ocean and between the Indian and the Pacific Oceans. Our results showed that spatial patterns of change in species richness and compositional similarity are driven by human and natural factors. The driving role of mean annual temperature is particularly consistent, and current reptile richness and compositional similarity patterns for both species groups are increasingly being shaped by the global temperature gradient.
Main conclusions
The globalization of human activity is eroding the regionalized character of insular herpetofaunas and leading to the emergence of global‐scale gradients of taxonomic composition and species richness. Projections of increasing rates of biological invasions, extinctions and climate change suggest that these changes are likely to be aggravated even further in the coming decades.
Abstract
Mediterranean pastures are experiencing strong changes in management, involving shifts from sheep to cattle-based livestock systems. The impacts of such shifts on biodiversity are still ...poorly understood. Here, we sought to contrast the grazing regime, vegetation structure, bird species richness and abundance, between sheep and cattle grazed parcels, to understand the mechanisms through which management decisions impact farmland birds. During spring 2019, we characterized livestock management, bird populations and sward structure in 23 cattle and 27 sheep grazed parcels. We used a Structural Equation Model to infer the direct and indirect effects of sheep and cattle grazing on birds. Although no effects were found on overall species richness, there were species-specific responses to sheep and cattle grazed systems. Grazing pressure (variable integrating stocking rate and the number of days in the parcel) had negative impacts on the prevalence/abundance of Zitting Cisticola, Corn Bunting and Little Bustard, either directly or indirectly, through the effects of grazing pressure on vegetation height. Animal density and vegetation cover had direct positive effects in
Galerida
spp. and Common Quail, respectively. Zitting Cisticola and Little Bustard also showed a direct response to livestock type. Our study emphasizes the importance of grazing pressure as a driver of negative impacts for bird populations in Mediterranean grasslands. Since the ongoing transition from sheep to cattle-based systems involves increases in stocking rate, and therefore potentially higher grazing pressure, we propose a policy change to cap the maximum allowed grazing pressure. At the landscape scale, a mix of sheep and cattle grazed fields would be beneficial for maintaining bird diversity.
Each year, hundreds of scientific works with species' geographical data are published. However, these data can be challenging to identify, collect, and integrate into analytical workflows due to ...differences in reporting structures, storage formats, and the omission or inconsistency of relevant information and terminology. These difficulties tend to be aggravated for non‐native species, given varying attitudes toward non‐native species reporting and the existence of an additional layer of invasion‐related terminology. Thus, our objective is to identify the current practices and drivers of the geographical reporting of non‐native species in the scientific literature. We conducted an online survey targeting authors of species regional checklists—a widely published source of biogeographical data—where we asked about reporting habits and perceptions regarding non‐native taxa. The responses and the relationships between response variables and predictors were analyzed using descriptive statistics and ordinal logistic regression models. With a response rate of 22.4% (n = 113), we found that nearly half of respondents (45.5%) do not always report non‐native taxa, and of those who report, many (44.7%) do not always differentiate them from native taxa. Close to half of respondents (46.4%) also view the terminology of biological invasions as an obstacle to the reporting of non‐native taxa. The ways in which checklist information is provided are varied, but mainly correspond to descriptive text and embedded tables with non‐native species (when given) mentioned alongside native species. Only 13.4% of respondents mention to always provide the data in automation‐friendly formats or its publication in biodiversity data repositories. Data on the distribution of non‐native species are essential for monitoring global biodiversity change and preventing biological invasions. Despite its importance our results show an urgent need to improve the frequency, accessibility, and consistency of publication of these data.
Each year, hundreds of species checklists are published. However, many of these checklists are difficult to identify, collect and integrate into analytical workflows, due to distinct data reporting structures, storage formats, the omission of relevant information or the use of ambiguous or inconsistent terminology. We conducted an online survey targeting authors of species regional checklists to identify the current practices and drivers of the geographical reporting of non‐native species in the scientific literature.
Humans have moved species away from their native ranges since the Neolithic, but globalization accelerated the rate at which species are being moved. We fitted more than half million distribution ...models for 610 traded bird species on the CITES list to examine the separate and joint effects of global climate and land‐cover change on their potential end‐of‐century distributions. We found that climate‐induced suitability for modelled invasive species increases with latitude, because traded birds are mainly of tropical origin and much of the temperate region is ‘tropicalizing.’ Conversely, the tropics are becoming more arid, thus limiting the potential from cross‐continental invasion by tropical species. This trend is compounded by forest loss around the tropics since most traded birds are forest dwellers. In contrast, net gains in forest area across the temperate region could compound climate change effects and increase the potential for colonization of low‐latitude birds. Climate change has always led to regional redistributions of species, but the combination of human transportation, climate, and land‐cover changes will likely accelerate the redistribution of species globally, increasing chances of alien species successfully invading non‐native lands. Such process of biodiversity homogenization can lead to emergence of non‐analogue communities with unknown environmental and socioeconomic consequences.
We fitted an ensemble including more than half million distribution models for 610 traded bird species on the CITES list, to examine the joint effects of global climate and land‐cover change on their potential end‐of‐century distributions. Climate suitability for modelled bird species will increase with latitude, because they are mainly of tropical origin and the temperate region is ‘tropicalizing’. Net forest gains across the temperate region could also increase the potential for colonization of low‐latitude birds.
Abstract
The standard theory of optimal jurisdictional size hinges on the existence of economies of scale in the provision of local public goods and services. However, despite its relevance for ...forced local amalgamation programs and related policies, the empirical evidence on the existence of such economies of scale remains elusive. The main goal of this paper is to produce an updated and comprehensive quantitative review of the existence of economies of scale in the provision of local public goods using a meta‐analysis approach to systematize the wide range of empirical approaches and modeling frameworks found in the previous literature. Our analysis confirms the presence of moderately increasing to constant returns to scale in the provision of local services with no reduction in the average costs of production in the delivery of most local public services beyond a certain, modest jurisdictional size, which many studies have estimated at 10,000 residents. Also, the potential for economies of scale differs at least across three traditional services: education, water and sanitation, and garbage collection, being highest for education and lowest for garbage collection. Our analysis also offers guidelines for future empirical research in this area. Physical output and production cost data should be used, together with translog specifications for the modeling of cost functions. Last, we find evidence that the determinants of output cost elasticity include bidirectional publication bias and population density but do
not
include the presence or absence of modern “lean” production technologies or the (perceived) capital intensity of the sector, contrary to conventional wisdom. These findings have significant policy implications for countries considering jurisdictional consolidation programs.
This study examined the multi-scale effects of farmland management on the assemblages of grassland wintering birds in Southern Portugal, evaluating the potential influences on bird conservation of ...ongoing transformations in agricultural landscapes. The bird assemblages of 42 grassland fields were characterised and related to three sets of variables reflecting field management, landscape context and large-scale spatial trends. Birds showed responses to the three sets of variables, with variation partitioning indicating that species richness was primarily influenced by landscape context, whereas abundances were mostly determined by field management. In general, high species richness was associated with small patches of arable land, diverse landscapes, high stream density and forest and shrub cover, which probably acted as sources of non-agricultural species to grassland fields. In contrast, fields located in homogenous arable landscapes tended to be species poor, though they were the most favourable for open farmland species of conservation concern (e.g. skylark, calandra lark and little bustard). Old grazed fallows were generally associated with the highest abundances of both invertebrate and seed-eating birds, particularly that of winter visitors. Seed-eating winter visitors were also associated with stubble fields. The results indicated that conservation of Iberian grasslands for wintering birds requires management at both the landscape and field scales. At the landscape level, large blocks of open farmland habitat need to be maintained. At the field level, conservation management should strive to maintain both stubble fields and old grazed fallows. The application of such prescriptions would require a combination of agri-environmental programs and land planning policies, whereby the financial support to individual farmers should be conditional on the maintenance of adequate landscape contexts at larger spatial scales.
E-commerce has become a booming market for wildlife trafficking, as online platforms are increasingly more accessible and easier to navigate by sellers, while still lacking adequate supervision. ...Artificial intelligence models, and specifically deep learning, have been emerging as promising tools for the automated analysis and monitoring of digital online content pertaining to wildlife trade. Here, we used and fine-tuned freely available artificial intelligence models (i.e., convolutional neural networks) to understand the potential of these models to identify instances of wildlife trade. We specifically focused on pangolin species, which are among the most trafficked mammals globally and receiving increasing trade attention since the COVID-19 pandemic. Our convolutional neural networks were trained using online images (available from iNaturalist, Flickr and Google) displaying both traded and non-traded pangolin settings. The trained models showed great performances, being able to identify over 90 % of potential instances of pangolin trade in the considered imagery dataset. These instances included the showcasing of pangolins in popular marketplaces (e.g., wet markets and cages), and the displaying of commonly traded pangolin parts and derivates (e.g., scales) online. Nevertheless, not all instances of pangolin trade could be identified by our models (e.g., in images with dark colours and shaded areas), leaving space for further research developments. The methodological developments and results from this exploratory study represent an advancement in the monitoring of online wildlife trade. Complementing our approach with other forms of online data, such as text, would be a way forward to deliver more robust monitoring tools for online trafficking.
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