Search

Questions: Plants largely vary in their capacity for foliar water uptake (FWU), that is, the capacity to increase leaf water content by directly absorbing water from leaf‐wetting events. Climate change will reduce leaf wetting and increase drought events. Therefore, we need a better understanding of the underlying traits and mechanisms that facilitate FWU. Location: Seasonally dry tropical montane grasslands in Brazil (Campos de Altitude). Methods: We measured FWU and leaf traits related to wettability, surface conductance, water potential and water storage on up to 55 plant species. By using Direct Acyclic Graph theory and Bayesian modelling, we tested how those leaf traits affect FWU. Results: We found that stomatal conductance largely explained interspecific variation in FWU, which was also favoured in species with hydrophilic leaves, high cuticular conductance, more negative leaf water potentials, low dry‐matter content, isohydric behaviour, and more elastic cell walls. Conclusions: Due to the existence of trade‐offs, not all species exhibit an optimal combination of traits that favours FWU. Instead, co‐occurring species have achieved a similar capacity for FWU through distinct trait combinations. Consequently, species engaged in FWU may exhibit differential vulnerabilities to climate change as they can cope with drought using other strategies beside FWU. [ABSTRACT FROM AUTHOR]

Restoration actions can halt biodiversity loss and rescue its services. However, in order to be effective, priority areas for restoration should be chosen based on objective large‐scale restoration planning. Here, a multicriteria graph theory framework was used to propose restoration priority areas for the Brazilian Caatinga, the largest seasonally dry tropical forest of the New World, based on landscape resilience, landscape connectivity and biodiversity conservation value, focusing on threatened endemic plant species.We applied this graph theory framework to 10,406 Caatinga catchment basins. Vegetation cover and within‐catchment connectivity were used to select catchments of intermediate landscape resilience, which in principle offer more effective opportunities for restoration. Then, such catchments were independently classified into (a) three classes according their contribution for between‐catchment connectivity and (b) three classes according their value for biodiversity conservation, estimated by the richness of threatened, endemic plant species. By the integration of landscape resilience, landscape connectivity and biodiversity conservation values, three priority classes for restoration were generated.The multicriteria framework generated several restoration priority cut‐offs. Prioritization based on landscape resilience selected 36% of the Caatinga catchments as high priority for restoration. By independently adding landscape connectivity and biodiversity conservation value, only 12% and 3% of the catchments, respectively, were considered as high priority. By combining all three criteria, 9% of the catchments were selected as high priority and <1% as top priority for restoration.Synthesis and applications. Restoration of drylands can contribute immensely to the conservation of its threatened biodiversity but large‐scale planning is quintessential. Here, a multicriteria graph theory framework was applied to indicate priority areas for restoration, which maximizes the effectiveness of restoration actions, landscape connectivity for climate change adaptation and conservation of threatened species. The framework was applied to the Caatinga, the largest seasonally dry tropical forest of the new world, but it can be applied world‐wide under different budged limitations and spatial scales, being useful for private, state and federal initiatives. [ABSTRACT FROM AUTHOR]

Habitat loss and fragmentation threat animal populations worldwide. Agriculture has changed the Cerrado's landscape, in central Brazil, where native vegetation remnants are embedded in a non-natural matrix that can be resistant to animal movement. Felines, as carnivores, play an important ecosystem role as predators and are sensitive to habitat fragmentation. The long-term sustainability of small cat populations depends on the connectivity among natural remnants. The Emas National Park (ENP) is an important protected area located in the southwestern of the state of Goiás, a region highly modified by agriculture. We evaluated the landscape connectivity in the surrounding landscape of the ENP for small wildcats of the Cerrado; the margay, southern tiger cat, pampas cat, ocelot and the jaguarundi, based on their dispersal ability and habitat preferences. The habitat availability varied according to each species, the jaguarundi being the species with more habitat available and the margay with less. The ENP is important for the pampas cat and jaguarundi, and the Taquari River Sources State Park (TRSSP) is important for the ocelot, jaguarundi and for the southern tiger cat. The region is of great biological relevance and the lack of remnants around the ENP evidence failure in land management. The method used is a tool to identify priority fragments for conservation and management of the landscape for biodiversity. [ABSTRACT FROM AUTHOR]

• The study integrates socio-environmental analysis using urban configuration and landscape ecology models to examine spatial networks in Pelotas, Brazil. • The article discusses the relationship and statistical correlation between urban and ecological networks. • The methodology represents a valuable tool for urban planners and researchers to create and better understand urban green areas. • The methodology is applied in a specific area of Pelotas, Brazil. Urbanization has been expanding rapidly in Brazil, negatively impacting the natural environment. Achieving sustainable development requires understanding the interdependencies between the social and natural worlds and finding a balance between them. Resilient urban planning considering green infrastructure can generate socio-environmental benefits through ecological connections. To achieve this, an integrated study between the social and environmental spheres is required, which are often developed separately. Thus, this investigation aims to develop a socio-environmental analysis by adopting urban configuration and landscape ecology models and subsequently comparing their respective outcomes. To this end, two models of spatial networks were examined in a sector of Pelotas, Brazil, based on graph theory and centrality measures. The urban configuration model was used to analyze human mobility in urban networks, while the landscape ecology model was used to study the butterfly species Heliconius erato phyllis in ecological networks. Our findings show no significant correlation between the outcomes generated by the two models, indicating a lack of cohesion in the location and connection of green infrastructure in the study area. This methodology represents a valuable tool for urban planners and researchers seeking to gain new insights into the performance of urban green areas while considering both human and species-related factors. [ABSTRACT FROM AUTHOR]

Purpose: The research aims to propose a methodology to estimate the reliability of the Brazilian airport network (domestic passenger traffic), based on the centrality of airports (Network Theory). Design/methodology: The applied methodologies are related to Network Theory, a branch of Graph Theory, and reliability. Reliability is associated with the good functioning of a product or system, the absence of breaks or failures in each period and the environmental conditions of use of the item. The data used refer to the period 2000-2018 and were obtained from the sector's regulatory body in Brazil. The study allows to estimate the reliability of the airport network, based on the centrality of airports (Network Theory). Findings: The results allow airports to be classified into three groups: adequate context, worrying context and critical context, thus signalling airports that may stop operating regular domestic traffic. Research limitations/implications: The study does not aim to overlap or replace conventional analyses, recognized by the results, and applied over time. However, to present a new tool that allows the monitoring and preliminary analysis of airport networks, mainly domestic and regional networks, signalling to airport operators, regulators, and airlines the need for intervention (measures to reverse the trend) in the network, thus allowing, economic development and equitable access to all regions. Originality/value: The proposal of a complementary methodology based on the centrality of airports to analyze operational continuity. [ABSTRACT FROM AUTHOR]

Goal: This paper presents an analysis of the Brazilian air network based on the measure of h centrality. Design / Methodology / Approach: The purpose of this study is to define and determine the central network using the concepts of h-centrality. Method adapted from graph theory concepts with bibliometrics, especially the h-index. From the center of this index will be listed the most used airports to define the Brazilian central network and thus determinate the type h-index of Brazil. Results: The main airports in the results represent more than 50% of the homologated flights in Brazil. Limitations of the investigation: The centrality measure presents the situation at the moment when the data were analyzed. In the original h-index this notion reflects a history of the articles published by each author, but in the case of airports the market dynamics changes the behavior of the network. Practical implications: This model of air flight frequencies assists in public policy guidelines and planning both in air traffic control and in the verification of system impacts. Originality / Value: The method seeks to provide the list with main important airports without any prior definition by a decision maker. [ABSTRACT FROM AUTHOR]

The mangrove landscapes of the Ratones River and Itacorubi, located in the Municipality of Florianópolis, South of Brazil, are environmentally fragmented due to anthropogenic use of the soil, which hinders the dispersal of their native species. For the maintenance of ecological connectivity, this paper aims to identify the most critical habitat fragments of both landscape mangroves and to restore its ecosystem benefits. However, different metrics of Graph Theory provide distinct results of connectivity. Thus, this work also proposes a novel method to combine various connectivity metrics in a concise measurement. All investigated metrics make use of probabilistic models related to the displacement of an endangered species ( Lontra longicaudis ) of the local fauna. After the identification of the most critical habitat fragments, they were analyzed, structurally and functionally, on the landscape. This study provides guidelines for environmental management for the most critical and maintenance of the least critical fragments. [ABSTRACT FROM AUTHOR]

According to graph theory, the frequency distribution of trophic interactions within a food web has deep structural implications, as it can highlight the presence of patterns associated with the web and indicate whether the properties of the web are independent of its size. A hypothesis is that 'small-world' food webs are sensitive to the loss of species with the highest values. Therefore, the present work aimed to evaluate the degree to which a subtropical food web in Southern Brazil displays small-world patterns and their resistance. As part of the assessment, we evaluated the topological redundancy values of species in the food web and then we simulated the exclusion of these species (such as sharks and sea birds), and also the exclusion of high centrality species (such as squids Loligo sp., portunid swimming crabs and the cutlassfish Trichiurus lepturus). The food web showed a 'broad-scale' distribution of connections by node, and a small-world pattern. As expected, a simplification of the network was observed after elimination of some species with high centrality. However, the food web was resistant to the loss of species with low topological redundancy, probably because these species occupy a high trophic level and do not participate in lots of routes within the food web. We highlight however, the importance of the application of multiple analyses to evaluate the importance of components in food webs, and fisheries management plans should consider both species of high centrality values and species with low topological redundancy. [ABSTRACT FROM AUTHOR]

Background: There have been significant challenges in understanding functional brain connectivity associated with adolescent depression, including the need for a more comprehensive approach to defining risk, the lack of representation of participants from low- and middle-income countries, and the need for network-based approaches to model connectivity. The current study aimed to address these challenges by examining resting-state functional connectivity of frontolimbic circuitry associated with the risk and presence of depression in adolescents in Brazil., Methods: Adolescents in Brazil ages 14 to 16 years were classified into low-risk, high-risk, and depressed groups using a clinical assessment and composite risk score that integrates 11 sociodemographic risk variables. After excluding participants with excessive head movement, resting-state functional magnetic resonance imaging data of 126 adolescents were analyzed. We compared group differences in frontolimbic network connectivity using region of interest-to-region of interest, graph theory, and seed-based connectivity analyses. Associations between self-reported depressive symptoms and brain connectivity were also explored., Results: Adolescents with depression showed greater dorsal anterior cingulate cortex (ACC) connectivity with the orbitofrontal cortex compared with the 2 risk groups and greater dorsal ACC global efficiency than the low-risk group. Adolescents with depression also showed reduced local efficiency and a lower clustering coefficient of the subgenual ACC compared with the 2 risk groups. The high-risk group also showed a lower subgenual ACC clustering coefficient relative to the low-risk group., Conclusions: These findings highlight altered connectivity and topology of the ACC within frontolimbic circuitry as potential neural correlates and risk factors of developing depression in adolescents in Brazil. This study broadens our understanding of the neural connectivity associated with adolescent depression in a global context., (Copyright © 2022 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

Effective implementation of Marine Protected Areas (MPA) networks depends on social participation into management. In this study, a multilayered network analysis was used to understand patterns of social participation in MPA management in Brazil. To this end, managers were invited to answer an online questionnaire about interaction with social actors in 7 management activities. Engagement in management activities was represented as interactions between social actors and MPAs. Different types of management activity were represented as separate layers. All responding MPAs (n = 22) reported interactions with social actors, resulting in a network with 141 nodes connected by 182 edges. Governmental Organizations (GO) prevailed in surveillance and formal training activities, research was dominated by universities, monitoring activities were shared mainly by universities and Non-Governmental Organizations (NGOs), and community groups only had strong participation in environmental education activities. The network had low "edge loss" resilience with dependency on the participation of social actors in the management councils to maintain its current levels of connectivity. GOs that have important roles in the protection of terrestrial ecosystems have a restricted impact as higher-level coordinators of MPAs activities. Thus, the capacity building falls mainly on individual MPAs. Management councils are supposed to be the "town halls" where the different social sectors come together to discuss environmental problems in Brazil. However, some constraints must still exist, since only 51 % of Brazilian MPAs have legally instituted their councils. We suggest that their effective implementation, as ordered by law, is the best starting point to improve the dismal situation of Brazilian MPAs. [ABSTRACT FROM AUTHOR]

Cities continue to grow worldwide, and the highly modified urban landscape becomes an inhospitable environment for many species because the natural vegetation cover is commonly fragmented, and the remnants are often isolated. Protected Areas (PAs) located surrounding or within urban areas may not achieve their goal of protecting local or regional biodiversity. Thus, an urban ecological network is essential to support their PAs. Thus, this study aimed at assessing the PAs connectivity in an urban landscape in Brazil and understanding whether urban forest fragments can support an urban ecological network. Besides spatial models based on functional connectivity and graph theory, we used participatory techniques to design the resistance surface and the least-cost paths (LCPs) for Atlantic Forest birds. The results showed critical paths (LCPs), important areas for restoration programs for improving PAs connectivity, and essential forest fragments for conservation and restoration. Although the landscape has a forest structure with 1873 forest fragments and 516 links through which the LCPs were structured, most forest fragments and LCPs cannot provide the necessary support for the PAs connectivity. The current ecological network is dependent on forest fragments neighboring (outside PAs) and the flux dispersions occurred mainly in the peri-urban areas. Riparian zones and anthropic grasslands also showed importance for the PAs connectivity. We identified only 28 forest fragments spatially connected, presenting several sizes, and located near large forest areas, relevant PAs, and riparian zones. Six of these forest fragments, smaller than ten hectares and strategically located in the urban matrix, were indicated for restoration actions. The current low connectivity among PAs brings the importance of native vegetation restoration in the riparian zone and anthropic grassland and the importance of the periurban areas to promote biodiversity connectivity in the urban landscape. [Display omitted] [ABSTRACT FROM AUTHOR]

The city of Curitiba, located at Southern Brazil, is recognized by its urban planning structured on three pillars: land use, collective transportation, and traffic. With 3.8 million people in its metropolitan area, the public transport system deals with approximately 2.5 million passengers daily. The structure and properties of such a transportation system have substantial implications for the urban planning and public politics for sustainable development of Curitiba. Therefore, this paper analyzes the structure of the public transportation system of Curitiba through the theory of complex networks in a static approach of network topology and presents a comparative analysis of the results from Curitiba, three cities from China (Shanghai, Beijing, and Guangzhou), and three cities from Poland (GOP, Warszawa, and Łódź). The transportation network was modeled as a complex network with exact geographical coordinates of its bus stops. In all bus lines, the method used was the P-Space. The results show that this bus network has characteristics of both small-world and scale-free networks. [ABSTRACT FROM AUTHOR]

The article seeks to explore the evidence related to the sectoral patterns of structuring of the university-industry relations in Brazil, departing from the information extracted from the database of the Brazil Survey Research, with the analytical contribution of graph theory and its centrality measures. The empirical results allow us to identify some important constraints of the university-industry interactions in Brazil. In particular, we highlight the importance of locational aspects in conditioning the actions of universities as producers of science and technology for the productive sector and a tendency to relatively more intense interaction with less knowledge-intensive sectors, compared to so-called science based sectors. [ABSTRACT FROM AUTHOR]

This article addresses the spatial decision‐making of loggers and implications for forest fragmentation in the Amazon basin. It provides a behavioral explanation for fragmentation by modeling how loggers build road networks, typically abandoned upon removal of hardwoods. Logging road networks provide access to land, and the settlers who take advantage of them clear fields and pastures that accentuate their spatial signatures. In shaping agricultural activities, these networks organize emergent patterns of forest fragmentation, even though the loggers move elsewhere. The goal of the article is to explicate how loggers shape their road networks, in order to theoretically explain an important type of forest fragmentation found in the Amazon basin, particularly in Brazil. This is accomplished by adapting graph theory to represent the spatial decision‐making of loggers, and by implementing computational algorithms that build graphs interpretable as logging road networks. The economic behavior of loggers is conceptualized as a profit maximization problem, and translated into spatial decision‐making by establishing a formal correspondence between mathematical graphs and road networks. New computational approaches, adapted from operations research, are used to construct graphs and simulate spatial decision‐making as a function of discount rates, land tenure, and topographic constraints. The algorithms employed bracket a range of behavioral settings appropriate for areas of terras devolutas, public lands that have not been set aside for environmental protection, indigenous peoples, or colonization. The simulation target sites are located in or near so‐called Terra do Meio, once a major logging frontier in the lower Amazon Basin. Simulation networks are compared to empirical ones identified by remote sensing and then used to draw inferences about factors influencing the spatial behavior of loggers. Results overall suggest that Amazonia's logging road networks induce more fragmentation than necessary to access fixed quantities of wood. The paper concludes by considering implications of the approach and findings for Brazil's move to a system of concession logging. [ABSTRACT FROM AUTHOR]

The correlation matrix of stocks returns is used in order to create maps of the São Paulo Stock Exchange (BM&F-Bovespa), Brazil's main stock exchange. The data refer to the year 2010, and the correlations between stock returns lead to the construction of a minimum spanning tree and of asset graphs with a variety of threshold values. The results are analyzed using techniques of network theory. Also, using data from 2007 to 2010, a study is made on the dynamics of the network formed by stocks from that same stock exchange. [ABSTRACT FROM AUTHOR]

Loss of connectivity is one of the main causes of decreases in habitat availability and, thus, in species abundance and occurrence in fragmented landscapes. It is therefore important to measure habitat connectivity for conservation purposes, but there are several difficulties in quantifying connectivity, including the need for species movement behavioral data and the existence of few consistent indices to describe such data. In the present study, we used a graph theoretical framework to measure habitat availability, and we evaluate whether this variable is adequate to explain the occurrence pattern of an Atlantic rainforest bird ( Pyriglena leucoptera, Thamnophilidae). The playback technique was used to parameterize the connectivity component of habitat availability indices and to determine the presence or absence of the study species in forest patches. Patch- and landscape-level habitat availability indices were considered as explanatory variables. Two of these were landscape-level indices, which varied in terms of how inter-patch connections are defined, using either a binary or probabilistic approach. This study produced four striking results. First, even short open gaps may disrupt habitat continuity for P. leucoptera. Second, the occurrence of P. leucoptera was positively affected by habitat availability. Third, proper measures of this explanatory variable should account for the landscape context around the focal patch, emphasizing the importance of habitat connectivity. Finally, habitat availability indices should consider probabilistic and not binary inter-patch connections when intending to explain the occurrence of bird species in fragmented landscapes. We discuss some conservation implications of our results, stressing the advantages of an ecologically scaled graph theoretical framework. [ABSTRACT FROM AUTHOR]

Functional connectivity is known to have an important, positive influence on species persistence. Measurements of functional connectivity traditionally focus on structural attributes of landscapes such as the distance and matrix type between habitat patches as well as on how species interact with those structural attributes. However, we propose that the social behavior of a species, through conspecific and heterospecific attraction, will also impact connectivity by changing how dispersers move with respect to each other and occupied patches. We analyzed functional connectivity patterns using circuit and graph theory for golden-headed lion tamarins ( Leontopithecus chrysomelas) in Brazil under three scenarios. In the first scenario, we looked at connectivity without the effects of attraction under varying maximum dispersal distance and ecological movement cost thresholds. In the second scenario, we allowed dispersers to travel over more hostile matrix than they normally would to reach an occupied patch. In the final scenario, we allowed dispersers to move only to occupied patches. We found that, according to the first scenario, range-wide functional landscape connectivity for golden-headed lion tamarins is low at realistic maximum dispersal distance and movement cost thresholds. Incorporating the effects of conspecific or heterospecific attraction would increase functional connectivity, in the case of scenario two, or decrease functional connectivity, in the case of scenario three. Because conspecific/heterospecific attraction can have an impact on movement for some species, this factor should be incorporated in assessments of functional connectivity patterns for social species and others where patch occupancy is likely to influence the movements of dispersers. [ABSTRACT FROM AUTHOR]

Abstract: This article presents a procedure for establishing and ranking the areas that are candidates for building truck cargo terminals, based on the analytic hierarchy process (AHP) and considering location factors, with focus on accessibility considerations, expressed by indicators derived from graph theory. Accessibility is thus defined objectively for each area, contemplating its needs regarding production or consumption of cargo or promotion of intermodal transport of products. The proposed approach determines the most suitable area for locating the terminal according to the perception of each actor participating in the process as well as the set of actors, seeking to conjugate conflicting interests and facilitate convergence and the establishment of negotiated solutions. With this, it provides a more transparent and participative decision-making process and supplies basic elements for government bodies to formulate their socioeconomic development policies. The application of this procedure in the greater Rio de Janeiro metropolitan region demonstrated its feasibility in developing countries and in contexts with restricted data, funding and planning. [Copyright &y& Elsevier]

Abstract: This Letter addresses the problem of modeling the highway systems of different countries by using complex networks formalism. More specifically, we compare two traditional geographical models with a modified geometrical network model where paths, rather than edges, are incorporated at each step between the origin and the destination vertices. Optimal configurations of parameters are obtained for each model and used for the comparison. The highway networks of Australia, Brazil, India, and Romania are considered and shown to be properly modeled by the modified geographical model. [Copyright &y& Elsevier]

Abstract: Leaf area index (LAI) is a key parameter that affects the surface fluxes of energy, mass, and momentum over vegetated lands, but observational measurements are scarce, especially in remote areas with complex canopy structure. In this paper we present an indirect method to calculate the LAI based on the analyses of histograms of hemispherical photographs. The optimal threshold value (OTV), the gray-level required to separate the background (sky) and the foreground (leaves), was analytically calculated using the entropy crossover method (Sahoo, P.K., Slaaf, D.W., Albert, T.A., 1997. Threshold selection using a minimal histogram entropy difference. Optical Engineering 36(7) 1976–1981). The OTV was used to calculate the LAI using the well-known gap fraction method. This methodology was tested in two different ecosystems, including Amazon forest and pasturelands in Brazil. In general, the error between observed and calculated LAI was ∼6%. The methodology presented is suitable for the calculation of LAI since it is responsive to sky conditions, automatic, easy to implement, faster than commercially available software, and requires less data storage. [Copyright &y& Elsevier]

One of the main consequences of habitat loss and fragmentation is the increase in patch isolation and the consequent decrease in landscape connectivity. In this context, species persistence depends on their responses to this new landscape configuration, particularly on their capacity to move through the interhabitat matrix. Here, we aimed first to determine gap-crossing probabilities related to different gap widths for two forest birds ( Thamnophilus caerulescens, Thamnophilidae; and Basileuterus culicivorus, Parulidae) from the Brazilian Atlantic rainforest. These values were defined with a playback technique and then used in analyses based on graph theory to determine functional connections among forest patches. Both species were capable of crossing forest gaps between patches, and these movements were related to gap width. The probability of crossing 40 m gaps was 50% for both species. This probability falls to 10% when the gaps are 60 m (for B. culicivorus) or 80 m (for T. caerulescens). Actually, birds responded to stimulation about two times more distant inside forest trials (control) than in gap-crossing trials. Models that included gap-crossing capacity improved the explanatory power of species abundance variation in comparison to strictly structural models based merely on patch area and distance measurements. These results highlighted that even very simple functional connectivity measurements related to gap-crossing capacity can improve the understanding of the effect of habitat fragmentation on bird occurrence and abundance. [ABSTRACT FROM AUTHOR]

Abstract: Since Demirjian''s system of estimating dental maturity was first described, many researchers from different countries have tested its accuracy among diverse populations. Some of these studies have pointed out a need to determine population-specific standards. In Brazil, the Northeast region is the one that most suffers the negative impact of exodus, specially related to the increase of abandoned children in the cities. The aim of this study was to test the accuracy of Demirjian''s system for assessing the dental maturity of northeastern Brazilian children, so as to present a scale for maturity score conversion into dental age developed specifically for this population. This could be used for forensic, anthropological and legal matters, and also as a model for other countries attempting to formulate their own conversion scales. Panoramic radiographs of 1,491 children (821 females and 670 males), aged 7 to 13 years, from Ceará state, northeast Brazil, were assessed by a single observer to determine dental age (DA) according to Demirjian''s system. The mean percentage of intra-observer agreement was 86.6%, with a mean Cohen''s Kappa coefficient of 0.67 (substantial agreement). The DA was compared by paired t-test to subjects’ chronological age (CA). The differences between CA and DA in all age groups were statistically significant (p <0.0001), demonstrating a great advancement in DA among Brazilians. Scatter plots were drawn for both genders, and the data were fitted to a growth curve, y =100/(1+e−a(x – b)). Graphs corresponding to the 50th percentile curves were produced. A table with new values for the conversion of maturity score into dental age for northeastern Brazilian children is presented. The great advancement in DA, as obtained by Demirjian''s system in this population, justified the determination of specific scores for dental maturity assessment. [Copyright &y& Elsevier]