RESUMO

High rates of deforestation, either in the past or the present, affect many of the ecological processes in streams. Integrating deforestation history and the current landscape structure enhances the evaluation of ecological effects of land-use change. This is especially true when contemporary landscape conditions are similar but the temporal path to those conditions differs. One approach that has shown promise for evaluating biodiversity responses over time and space is the β-diversity partitioning, which combines taxonomic and functional trait-based approaches. We tested hypotheses related to stream fish assemblages' turnover in watersheds with different environmental conditions and deforestation histories. We sampled fish from 75 watersheds in the Machado River basin, Brazil, and environmental factors were quantified at multiple scales. Taxonomic turnover was higher than expected by chance, whereas functional turnover was lower than expected by the observed taxonomic turnover, indicating that deterministic processes are structuring these assemblages. The turnover, and the environmental factors differed among watersheds with different deforestation histories. Besides being scale-dependent, turnover patterns are also likely dependent on land use dynamics and involve time-lags.(AU)

Altas taxas de desmatamento, seja no passado ou no presente, afetam muitos processos ecológicos em riachos. Integrar o histórico do desmatamento à estrutura atual da paisagem melhora a avaliação dos efeitos ecológicos da mudança do uso do solo. Isto é especialmente verdadeiro quando as condições da paisagem contemporânea são semelhantes, mas seguiram trajetórias distintas. Uma abordagem promissora para avaliar as respostas da biodiversidade ao longo do tempo e espaço é a partição da diversidade-β, que combina abordagens taxonômica e funcional. Testamos hipóteses relacionadas à substituição das assembleias de peixes de riachos em microbacias com diferentes condições ambientais e histórias de desmatamento. Amostramos 75 microbacias na bacia do rio Machado, fatores ambientais foram quantificados em múltiplas escalas. A substituição taxonômica foi maior do que esperada pelo acaso, enquanto a substituição funcional foi menor do que o esperado pela substituição taxonômica, indicando que as assembleias são estruturadas por processos determinísticos. As substituições e fatores ambientais diferiram entre microbacias com históricos de desmatamento distintos. Além de serem escala-dependentes, os padrões de substituição provavelmente são dependentes da dinâmica do uso do solo, envolvendo defasagem temporal.(AU)

Assuntos

RESUMO

High rates of deforestation, either in the past or the present, affect many of the ecological processes in streams. Integrating deforestation history and the current landscape structure enhances the evaluation of ecological effects of land-use change. This is especially true when contemporary landscape conditions are similar but the temporal path to those conditions differs. One approach that has shown promise for evaluating biodiversity responses over time and space is the β-diversity partitioning, which combines taxonomic and functional trait-based approaches. We tested hypotheses related to stream fish assemblages' turnover in watersheds with different environmental conditions and deforestation histories. We sampled fish from 75 watersheds in the Machado River basin, Brazil, and environmental factors were quantified at multiple scales. Taxonomic turnover was higher than expected by chance, whereas functional turnover was lower than expected by the observed taxonomic turnover, indicating that deterministic processes are structuring these assemblages. The turnover, and the environmental factors differed among watersheds with different deforestation histories. Besides being scale-dependent, turnover patterns are also likely dependent on land use dynamics and involve time-lags.(AU)

Altas taxas de desmatamento, seja no passado ou no presente, afetam muitos processos ecológicos em riachos. Integrar o histórico do desmatamento à estrutura atual da paisagem melhora a avaliação dos efeitos ecológicos da mudança do uso do solo. Isto é especialmente verdadeiro quando as condições da paisagem contemporânea são semelhantes, mas seguiram trajetórias distintas. Uma abordagem promissora para avaliar as respostas da biodiversidade ao longo do tempo e espaço é a partição da diversidade-β, que combina abordagens taxonômica e funcional. Testamos hipóteses relacionadas à substituição das assembleias de peixes de riachos em microbacias com diferentes condições ambientais e histórias de desmatamento. Amostramos 75 microbacias na bacia do rio Machado, fatores ambientais foram quantificados em múltiplas escalas. A substituição taxonômica foi maior do que esperada pelo acaso, enquanto a substituição funcional foi menor do que o esperado pela substituição taxonômica, indicando que as assembleias são estruturadas por processos determinísticos. As substituições e fatores ambientais diferiram entre microbacias com históricos de desmatamento distintos. Além de serem escala-dependentes, os padrões de substituição provavelmente são dependentes da dinâmica do uso do solo, envolvendo defasagem temporal.(AU)

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Conservation initiatives overwhelmingly focus on terrestrial biodiversity, and little is known about the freshwater cobenefits of terrestrial conservation actions. We sampled more than 1500 terrestrial and freshwater species in the Amazon and simulated conservation for species from both realms. Prioritizations based on terrestrial species yielded on average just 22% of the freshwater benefits achieved through freshwater-focused conservation. However, by using integrated cross-realm planning, freshwater benefits could be increased by up to 600% for a 1% reduction in terrestrial benefits. Where freshwater biodiversity data are unavailable but aquatic connectivity is accounted for, freshwater benefits could still be doubled for negligible losses of terrestrial coverage. Conservation actions are urgently needed to improve the status of freshwater species globally. Our results suggest that such gains can be achieved without compromising terrestrial conservation goals.

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Mixed tree plantings and natural regeneration are the main restoration approaches for recovering tropical forests worldwide. Despite substantial differences in implementation costs between these methods, little is known regarding how they differ in terms of ecological outcomes, which is key information for guiding decision making and cost-effective restoration planning. Here, we compared the early ecological outcomes of natural regeneration and tree plantations for restoring the Brazilian Atlantic Forest in agricultural landscapes. We assessed and compared vegetation structure and composition in young (7-20 yr old) mixed tree plantings (PL), second-growth tropical forests established on former pastures (SGp), on former Eucalyptus spp. plantations (SGe), and in old-growth reference forests (Ref). We sampled trees with diameter at breast height (DBH) 1-5 cm (saplings) and trees at DBH > 5 cm (trees) in a total of 32 20 × 45 m plots established in these landscapes. Overall, the ecological outcomes of natural regeneration and restoration plantations were markedly different. SGe forests showed higher abundance of large (DBH > 20 cm) nonnative species, of which 98% were resprouting Eucalyptus trees, than SGp and PL, and higher total aboveground biomass; however, aboveground biomass of native species was higher in PL than in SGe. PL forests had lower abundance of native saplings and lianas than both naturally established second-growth forests, and lower proportion of animal dispersed saplings than SGe, probably due to higher isolation from native forest remnants. Rarefied species richness of trees was lower in SGp, intermediate in SGe and Ref and higher in PL, whereas rarefied species richness of saplings was higher in SG than in Ref. Species composition differed considerably among regeneration types. Although these forests are inevitably bound to specific landscape contexts and may present varying outcomes as they develop through longer time frames, the ecological particularities of forests established through different restoration approaches indicate that naturally established forests may not show similar outcomes to mixed tree plantings. The results of this study underscore the importance that restoration decisions need to be based on more robust expectations of outcomes that allow for a better analysis of the cost-effectiveness of different restoration approaches before scaling-up forest restoration in the tropics.

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Deforestation is a primary driver of biodiversity change through habitat loss and fragmentation. Stream biodiversity may not respond to deforestation in a simple linear relationship. Rather, threshold responses to extent and timing of deforestation may occur. Identification of critical deforestation thresholds is needed for effective conservation and management. We tested for threshold responses of fish species and functional groups to degree of watershed and riparian zone deforestation and time since impact in 75 streams in the western Brazilian Amazon. We used remote sensing to assess deforestation from 1984 to 2011. Fish assemblages were sampled with seines and dip nets in a standardized manner. Fish species (n = 84) were classified into 20 functional groups based on ecomorphological traits associated with habitat use, feeding, and locomotion. Threshold responses were quantified using threshold indicator taxa analysis. Negative threshold responses to deforestation were common and consistently occurred at very low levels of deforestation (<20%) and soon after impact (<10 years). Sensitive species were functionally unique and associated with complex habitats and structures of allochthonous origin found in forested watersheds. Positive threshold responses of species were less common and generally occurred at >70% deforestation and >10 years after impact. Findings were similar at the community level for both taxonomic and functional analyses. Because most negative threshold responses occurred at low levels of deforestation and soon after impact, even minimal change is expected to negatively affect biodiversity. Delayed positive threshold responses to extreme deforestation by a few species do not offset the loss of sensitive taxa and likely contribute to biotic homogenization.

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Agricultural expansion and intensification are major threats to tropical biodiversity. In addition to the direct removal of native vegetation, agricultural expansion often elicits other human-induced disturbances, many of which are poorly addressed by existing environmental legislation and conservation programmes. This is particularly true for tropical freshwater systems, where there is considerable uncertainty about whether a legislative focus on protecting riparian vegetation is sufficient to conserve stream fauna.To assess the extent to which stream fish are being effectively conserved in agricultural landscapes, we examined the spatial distribution of assemblages in river basins to identify the relative importance of human impacts at instream, riparian and catchment scales, in shaping observed patterns. We used an extensive dataset on the ecological condition of 83 low-order streams distributed in three river basins in the eastern Brazilian Amazon.We collected and identified 24,420 individual fish from 134 species. Multiplicative diversity partitioning revealed high levels of compositional dissimilarity (DS) among stream sites (DS = 0.74 to 0.83) and river basins (DS = 0.82), due mainly to turnover (77.8% to 81.8%) rather than nestedness. The highly heterogeneous fish faunas in small Amazonian streams underscore the vital importance of enacting measures to protect forests on private lands outside of public protected areas.Instream habitat features explained more variability in fish assemblages (15%-19%) than riparian (2%-12%), catchment (4%-13%) or natural covariates (4%-11%). Although grouping species into functional guilds allowed us to explain up to 31% of their abundance (i.e. for nektonic herbivores), individual riparian - and catchment - scale predictor variables that are commonly a focus of environmental legislation explained very little of the observed variation (partial R2 values mostly <5%).Policy implications. Current rates of agricultural intensification and mechanization in tropical landscapes are unprecedented, yet the existing legislative frameworks focusing on protecting riparian vegetation seem insufficient to conserve stream environments and their fish assemblages. To safeguard the species-rich freshwater biota of small Amazonian streams, conservation actions must shift towards managing whole basins and drainage networks, as well as agricultural practices in already-cleared land.

RESUMO

OBJECTIVE: To evaluate gingival and calculus status among schoolchildren 12 years of age using a geographic information system and multilevel analysis. METHODS: A total of 1 002 schoolchildren were selected from 18 municipal districts by means of cluster sampling, from among 25 public and private schools in Piracicaba, São Paulo, Brazil, in 2005. Examinations were carried out by a single calibrated examiner utilizing the criteria of the World Health Organization, as well as the Community Periodontal Index. Social, economic, and behavioral variables were recorded with the use of a questionnaire and were used in the individual analysis (first level). The variables "percentage of heads of families without income" and "percentage of illiterate heads of families" were used in the contextual analysis (second level). RESULTS: A geographic information system was constructed for mapping the distribution of gingival bleeding. The variables were visually distinguished in the maps and demonstrated a tendency toward better gingival health in the central areas of the city, which are recognized as more privileged. On the contextual level, only the "percentage of illiterate heads of families" was significantly associated to gingival bleeding. CONCLUSIONS: The study confirms better oral health status among schoolchildren from privileged families, but does not confirm the data regarding "income." The individuals from areas in which the heads of family did not have income were not associated to a higher prevalence of gingival problems. This suggests that these individuals are reasonably protected from the impact of social privation due to the actions of public health care services in the municipality.

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OBJECTIVE: To evaluate gingival and calculus status among schoolchildren 12 years of age using a geographic information system and multilevel analysis. METHODS: A total of 1 002 schoolchildren were selected from 18 municipal districts by means of cluster sampling, from among 25 public and private schools in Piracicaba, São Paulo, Brazil, in 2005. Examinations were carried out by a single calibrated examiner utilizing the criteria of the World Health Organization, as well as the Community Periodontal Index. Social, economic, and behavioral variables were recorded with the use of a questionnaire and were used in the individual analysis (first level). The variables "percentage of heads of families without income" and "percentage of illiterate heads of families" were used in the contextual analysis (second level). RESULTS: A geographic information system was constructed for mapping the distribution of gingival bleeding. The variables were visually distinguished in the maps and demonstrated a tendency toward better gingival health in the central areas of the city, which are recognized as more privileged. On the contextual level, only the "percentage of illiterate heads of families" was significantly associated to gingival bleeding. CONCLUSIONS: The study confirms better oral health status among schoolchildren from privileged families, but does not confirm the data regarding "income." The individuals from areas in which the heads of family did not have income were not associated to a higher prevalence of gingival problems. This suggests that these individuals are reasonably protected from the impact of social privation due to the actions of public health care services in the municipality.

OBJETIVO: Evaluar el estado gingival y la presencia de sarro en escolares de 12 años de edad mediante el empleo de un sistema de información geográfica y análisis de niveles múltiples. MÉTODOS: En el año 2005, se seleccionó a un total de 1 002 escolares de 18 distritos municipales mediante muestreo por grupos, con la participación de 25 escuelas públicas y privadas de Piracicaba, en el estado de São Paulo, Brasil. Un único examinador calibrado, que utilizó los criterios de la Organización Mundial de la Salud, así como el Índice Periodontal Comunitario, llevó a cabo los exámenes. Mediante un cuestionario, se registraron las variables sociales, económicas y conductuales, y estas se emplearon en el análisis individual (primer nivel). En el análisis contextual (segundo nivel), se utilizaron las variables "porcentaje de cabezas de familia sin ingresos" y "porcentaje de cabezas de familia analfabetas". RESULTADOS: Se construyó un sistema de información geográfica para elaborar mapas de la distribución de la hemorragia gingival. Los mapas, donde se pueden distinguir visualmente las variables, demostraron una tendencia hacia una mejor salud gingival en las zonas del centro de la ciudad, consideradas como privilegiadas. En el nivel contextual, únicamente el "porcentaje de cabezas de familia analfabetas" se asoció significativamente con el sangrado gingival. CONCLUSIONES: El presente estudio confirma una mejor salud bucodental en los escolares pertenecientes a familias privilegiadas, pero no confirma los datos en cuanto a "ingresos". Las personas residentes en zonas donde las cabezas de familia no tenían ingresos no presentaron una mayor prevalencia de problemas gingivales. Esto indica que estas personas, como consecuencia de las actividades de los servicios de atención de salud pública del municipio, están razonablemente protegidas de la repercusión de la privación social.

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The present study investigated the distribution profile of dental caries and its association with areas of social deprivation at the individual and contextual level. The cluster sample consisted of 1,002 12-year-old schoolchildren from Piracicaba, SP, Brazil. The DMFT Index was used for dental caries and the Care Index was used to determine access to dental services. On the individual level, variables were associated with a better oral status. On the contextual level, areas were not associated with oral status. However, maps enabled determining that the central districts have better social and oral conditions than the deprived outlying districts.

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