Sensitive and cost-effective indicators of aquatic ecosystem condition in Amazon streams are necessary to assess the effects of anthropogenic disturbances on those systems in a viable and ecologically meaningful manner. We conducted the present study in the municipality of Paragominas, state of Pará, northern Brazil, where we sampled adult dragonflies in 50 100-m-long wadeable stream sites in 2011. We collected 1769 specimens represented by 11 families, 41 genera and 97 species. The suborder Zygoptera contributed 961 individuals and Anisoptera 808. Among the 97 recorded species, nine were classified as useful indicators of ecological condition, with four species being associated with more degraded streams (three Anisoptera, one Zygoptera) and five with more preserved streams (all were Zygoptera). Anisoptera (dragonflies) tend to provide more useful indicators of more degraded environments because they have more efficient homeostatic mechanisms and are more mobile, enabling them to tolerate a wider range of environmental conditions. By contrast, Zygoptera (damselflies) tend to provide a more useful role as indicators of more preserved environments and high levels of environmental heterogeneity because of their smaller body sizes and home ranges and greater ecophysiological restrictions. We conclude from our assessment of this low-order Amazonian stream system that (i) the occurrence of specific odonate species is strongly associated with the configuration of riparian vegetation, (ii) agricultural activities appear to be the main factor determining changes in the composition of odonate assemblages and (iii) these insects can act as useful indicators of the ecological consequences of riparian habitat loss and disturbance. Because generalist species invade moderately degraded areas, those areas may have high species richness but host few species of Zygoptera. Therefore, preserving dense riparian vegetation is necessary to maintain aquatic ecological condition, and that condition can be rehabilitated by planting new trees. Both require enforcing existing environmental regulations, various types of incentives and educating local communities.
RESUMO -O monitoramento de fauna é um procedimento essencial na determinação da eficiência de uma unidade de conservação. Os objetivos deste artigo foram avaliar o uso de parcelas de areia para registro de pegadas de mamíferos, para estimar a riqueza de espécies que utilizam habitats cortados por estradas, e analisar a aplicabilidade do método em um programa de monitoramento. Os levantamentos foram conduzidos no Parque Estadual do Rio Doce-MG, através do uso de duas grades de amostragem compostas por três transectos paralelos, a diferentes distâncias da estrada (12, 82 e 152 m), monitorados durante os meses de março a novembro de 2000. As estimativas de riqueza de espécie foram obtidas pelo programa EstimateS, e o programa MONITOR foi utilizado para calcular o poder da análise para estimar uma probabilidade de detecção (p=0,90) de um declínio (5%) do número de espécies às margens da estrada. As estimativas de riqueza de espécies para os transectos variaram entre 5,99 (DP 0,99) e 15,07 (DP 1,75). Os resultados indicam que um programa de monitoramento precisaria de três levantamentos por ano, durante quatro anos consecutivos, utilizando o mesmo protocolo de amostragem para detectar um declínio (5%) no número de espécies que utilizam a estrada, com probabilidade de 0,90. O uso de parcelas de areia é um método de fácil aplicação, que se mostrou adequado para estimar a riqueza de espécies de mamíferos, podendo contribuir com informações e previsões para o manejo e a conservação destas espécies.Palavras-chave: Mamíferos, monitoramento e parcelas de areia. SAND-PLOT USE FOR MONITORING ROAD IMPACT ON MAMMAL SPECIES RICHNESS
ABSTRACT. STRUCTllRAL IIETEROGENErrV AI"D DIVERsrrv OI' SMALL MAMMAL~IN A SECONDARY FOREsr FRAGMENTOF MINAS GERAIS. BRASIL. The aim is lo delermine lhe rclalionship helween lhe diversily of small mammals and the slructural helerogeneity and/or seeondary suceessional slages in an Atlantic foresl fragment aI Viçosa (Minas Gerais). We used Sherman and hook live traps lo sample this fauna, monthly from may 1992 to april 1993 in lhree arcas: an ahandoned planlation of Melinis mil1llliJInra (campo) and lwo distincl forest arcas (capoeira and mala). The slruelural hclerogeneily was delermined as a funclion of lhe presence of dead lrees. pioneer species. epiphytes. lhe distances helween trees. lhe lree heighl and bas.11 area measured hy a modified quadrant sample melhod (ConAM & CURTtS 1945). It was sampled a lotai of 340 individuais bclonging to 17 species. The homogeneous plantalions had the highesl diversily (H" = 1.67). Among lhe lWO foresls stands lhe lcss helerogeneous capoeira had similar diversity (H" = 1.19) lhan lhe more helerogeneous stand. lhe mala (H' = 1.13). The unexpected higher diversily and species richness in lhe more homogeneous habitat may he explained hy some hidden faclor which decrease lhe compclilion for resources in lhis communily. KEY WORDS. Con1lnunily slrueture. habilal helerogeneily. small man1lnal divcrsity A grande diversidade de espécies observada nos Trópicos Úmidos pode ser correlacionada com a relativa estabilidade climática (KARR & ROTH 1971) e com a alta produtividade primária (PIANKA 1967). Entretanto, o padrão de biodiversidade faunística vem sendo alterado pelo crescente desenvolvimento econômico das regiões tropicais (WILSON 1988) que tem como resultado a fragmentação dos sistemas tlorestais dessas regiões.A Floresta Atlântica Brasileira é um dos ecossistemas em que as conseqüên-cias desse processo de colonização podem ser melhor visualizadas. Acredita-se que menos de I % da Mata Atlântica permanece em sua forma não-perturhada
General patterns of frugivory in two nearby communities, one suffering greater impact by humans (Sede) than the other (Barra Grande), in Sao Paulo, southeastern Brazil were quantified monthly from January 1999 to March 2000 to assign a conservation value to each species of plant and bird, under the assumption that the more interactions, which is a record of a fruit species eaten by a bird species, a species is part of, the more important it is in the community-wide maintenance of fruit frugivore interactions. Results showed that a total of 68 species of frugivores accounted for 397 interactions unevenly distributed between sites. A total of 103 plant species took part in 397 interactions with birds in both sites. Among other plant families, pioneer and second-growth species formed the bulk of interactions in Sede (Anacardiaceae, Flacourtiaceae, Euphorbiaceae, Rosaceae, Myrsinaceae, Solanaceae and Ulmaceae), whereas canopy and shade-tolerant tree species contributed the most interactions in Barra Grande (Lauraceae, Myrtaceae, Sapindaceae, Symplocaceae, and Loranthaceae). Twenty percent of all recorded bird and plant species in both communities were responsible for the majority of the interactions. The hooded berry-eater, Carpornis cucullatus, a canopy and mid-level species, had the highest number of interactions for both sites combined followed closely by an understorey species, the blue manakin, Chiroxiphia caudata. The same pattern of rank distribution was observed for plant species, except one melastome species, Miconia pusilliflora, in Barra Grande which had more than twice the number of interactions than any of its co-occurring species.
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