Leandro Juen

A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network

Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network (Rede Amazônia Sustentável, RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far.

Odonate biodiversity in terra‐firme forest streamlets in Central Amazonia: on the relative effects of neutral and niche drivers at small geographical extents

Abstract.  1. The Amazon region is formed primarily by a dense network of acid and nutrient‐poor streamlets. The stability of environmental conditions coupled with spatial constraints to dispersal turns these streamlets into an interesting arena to compare neutral and niche drivers for community organisation. Here, we evaluated the relative importance of local environmental conditions and regional dispersal limitation to determine beta‐diversity and distributional patterns of species richness of the adult Odonata assemblage present in the Adolpho Ducke Forest Reserve (Manaus, Amazon) river basins.

Effect of vegetation removal for road building on richness and composition of Odonata communities in Amazonia, Brazil

This study showed that the main impact on Odonata species of removal of riparian vegetation for road building was on community composition, since species richness remained unaltered. This result, most evident in damselflies, was probably driven by the entry of generalist species that replaced specialist species after the impact. We collected adult odonates in forested and deforested streams in the surroundings of Manaus, Amazonas, northern Brazil. We collected 380 specimens belonging to 32 odonate species. Erythrodiplax fusca and Argia sp. 1 could be used in biomonitoring programs, since they were significantly associated with deforested streams. Using odonate community composition and key species appears to be more efficient in biomonitoring programs than simply using species richness. Em nosso estudo mostramos que o principal impacto sobre as espécies de Odonata causado pela retirada da vegetação ciliar para a construção de estradas é a modificação na composição da comunidade, uma vez que a riqueza de espécies continua praticamente constante. Possivelmente, devido à entrada de espécies mais generalistas em detrimento das especialistas, que são extintas localmente após o impacto, e isso é mais evidente em Zygoptera. Coletamos em 100 m de igarapés localizados em áreas sem vegetação e em fragmentos florestais na região de Manaus-AM. Foram coletados 380 espécimes, distribuídos em 32 espécies. Dessas, Erytrhodiplax fusca e Argia sp. 1 podem ser utilizadas em programas de biomonitoramento pois mostraram uma associação com ambientes sem vegetação marginal. Nossos resultados indicam que a composição da comunidade de Odonata e o uso de espécies chaves são mais eficientes que a simples medida de riqueza para avaliar os impactos causados a esse grupo.

The influence of habitat integrity and physical-chemical water variables on the structure of aquatic and semi-aquatic Heteroptera

This work aimed to assess the effect of certain physical-chemical variables and the Habitat Integrity Index (HII) have on an aquatic and semi-aquatic heteropteran community. We collected in five streams (from 1st to 4th order) that differed in habitat integrity, in order to test 1) whether heteropteran richness decreases with the Habitat Integrity Index; and 2) whether richness responds to alterations in water physical-chemical variables, since these influence community structure. In each stream, linear transects of 100 m were demarcated. A total of 1425 specimens from 10 families, 30 genera and 67 morphospecies were collected. Species richness was correlated with the Habitat Integrity Index (HII), showing a positive relationship only for Gerromorpha. This may be due to the fact that streams with greater integrity offer nearby marginal vegetation where prey and shelter can be easily found, representing optimal places for oviposition and hunting. Species adapted to such conditions are more sensitive to alterations in the physical structure of rivers. Significant differences in the composition of Heteroptera and studied infra-orders were also observed, which suggests that the anthropic disturbances over these sites have changed these insect communities. Our results indicate that the alteration in riparian areas can lead to significant changes in Heteroptera composition, even though species richness was not affected. The physical-chemical variables showed no influence on the distribution of species. This result suggests that the environment presented insufficient variation that could cause changes in the investigated community, which implies that factors other than those analyzed here may explain such variation. Three species Rhagovelia trailli (White, 1879), Rhagovelia sp. 4 and Tenagobia incerta (Lundblad, 1928) were considered to be indicators of pristine sites. The results indicate that aquatic and semi-aquatic Heteroptera and more specifically the sub-order Gerromorpha can be an important tool to assess environmental habitat integrity and enhance conservation actions of riparian forests.

Odonate assemblage structure in relation to basin and aquatic habitat structure in Pantanal wetlands

Structural properties of aquatic habitats are the basis of several theories produced to explain the functioning of aquatic environments. We predicted a longitudinal change of ecosystem properties along the river, and also that potamal areas of the river are similar to lakes. In rivers with periodic floods we also expect a high degree of similarity due to increased environmental similarity and increase dispersal of component species. Otherwise, rivers must be conceived as a landscape element with an intrinsic hierarchical nature and dispersal among its parts are constrained by this structure. Under this view, we also could expect that different basin or different “micro-basin” could present communities that are historically different in their general properties. Here, we aimed to describe odonate larval communities in the Pantanal Mortes-Araguaia river basin in Brazil comparing the composition, species richness and community structure between lakes and rivers, and also the possible differences among river basins. The field work was done in three rivers and three lakes chosen to conform to a paired experiment, each pair in a different river basin. An aggregated sampling unit was used based on Ekman dredge and D-nets replicated on each site. We sampled 936 individuals distributed in 30 genera and a total of 34 morphotypes. There was no difference in species richness among lakes and rivers, but a marked difference among basins. Samples from the same basin present a higher similarity of the species abundance relations than among river or lake samples. We also did not observed differences in composition and community structure between large rivers and lakes, in the same basin. The results supported the concept of structural similarity between large rivers and lakes and the differences observed among basins could indicate historical events in colonization that are shaping communities characteristics.

Effects of marginal vegetation removal on Odonata communities

OBJETIVOS: Com o intuito de avaliar os efeitos de mudancas na integridade ambiental sobre os individuos da comunidade de Odonata da sub-bacia do rio Borecaia, testamos a hipotese de que a riqueza de Anisoptera seria afetada positivamente pela remocao da vegetacao; por outro lado, a riqueza Zygoptera seria prejudicada em virtude de suas necessidades ecofisiologicas; METODOS: Selecionamos 10 riachos de ordens similares, seis classificados como preservados e quatro como alterados. Riachos classificados como preservados apresentaram valores do Indice valores de Integridade Habitat (HII) acima de 0.70 e mata continua nas duas margens com uma largura minima de 70 metros. Cada ponto foi amostrado tres vezes em dias diferentes. O efeito de remocao de vegetacao sobre a riqueza foi avaliada utilizando Jackknife de primeira ordem; RESULTADOS: A diminuicao da integridade fisica (mensurada com o IIH) dos corregos nao exerceu efeito significativo sobre a riqueza estimada para a Ordem Odonata. Porem, a riqueza estimada de Anisoptera apresentou uma relacao inversa com a integridade (r2 = 0.485; p = 0.025), mostrando que com o aumento da integridade houve uma reducao na sua riqueza de especies; DISCUSSAO: Como um padrao geral, Anisoptera apresenta maiores valores de riqueza em locais alterados; por outro lado, Zygoptera apresenta maiores valores em preservados. Devido suas restricoes ecofisiologicas Odonata apresentou uma grande variacao na sua composicao e riqueza de especie entre os dois tipos de ambientes, isso reforca o potencial da ordem em estudos de monitoramento ambiental e tambem mostra que Zygoptera sera mais afetada pelas transformacoes de habitat. No entanto, futuros estudos incluindo mais amostras e diferentes corregos sao necessarios para confirmar este padrao sendo uma linha de pesquisa interessante para trabalhos futuros.

Composição e distribuição da fauna de Ephemeroptera (Insecta) em área de transição Cerrado-Amazônia, Brasil

The objective of this study was to respond if exist a pattern on the spatial distributions of Ephemeroptera nymphs in different streams and rivers from Suia-Micu Basin, MT, and how the streams are classifying according to the species composition. Were sample 12 streams and rivers, in three periods of the year. Were collected 1,356 individuals, distributed in seven families, 31 genus and 42 species and/or morphospecies. The most abundant locals were semi-lentics and with few shaded suggering that most light in the system offer, allochthonous material and autochthonous material like food resources. The greater estimates richness was found in lotic places, emphasizing that the Ephemeroptera presents greater richness in these places, once water current is essential for organic matter transporting. So much in the grouping analysis (TWINSPAM) as in the ordination (DCA) was observed the separation of lotic and semi-lentic environments as for species composition. It had a gradient in the composition similarity of lotic and small streams for lotic and big stream and for last, semi-lentics. The results of this study show that the physic structure of aquatic environments affect species composition. In that way, retreat of riparian vegetation and streams dam up can take significant losses in the diversity.

Fluctuating Asymmetry and Wing Size of Argia tinctipennis Selys (Zygoptera: Coenagrionidae) in Relation to Riparian Forest Preservation Status

Effects of riparian vegetation removal on body size and wing fluctuating asymmetry (FA) of Argia tinctipennis Selys (Odonata: Coenagrionidae) were studied in the River Suiá-Miçú basin, which is part of the Xingu basin in Brazilian Amazonia. A total of 70 specimens (n = 33 from preserved and n = 37 from degraded areas) was measured. Five wing measures of each wing (totalizing ten measured characters) were taken. Preserved and degraded points presented non-overlapped variations of a Habitat Integrity Index, supporting the environmental differentiation between these two categories. FA increases in degraded areas approximately four times for the width between the nodus and proximal portion of the pterostigma of forewings (FW), two times for the width of the wing in the region of nodus of FW, and approximately 1.7 times for the number of postnodal cells of FW. The increase is almost five times for the width between the nodus and the proximal portion of the pterostigma of hind wings (HW), three times for the number of postnodal cells of HW, and approximately 1.6 times the width between quadrangle and nodus of HW. Individuals of preserved sites were nearly 3.3% larger than for degraded sites, based on mean hind wing length. Our results supports that the development of A. tinctipennis in degraded areas is affected by riparian vegetation removal and may reflect in wing FA variations. Consequently, these FA measures may be a useful tool for bioassessment using Odonata insects as a model.

Dragonfly endemism in the Brazilian Amazon: competing hypotheses for biogeographical patterns

Many hypotheses have been proposed to explain the origin and maintenance of the Amazonian diversity with special place for the theory of isolation by rivers and a set of hypothesis related to contemporary environmental dissimilarity. We explore those hypotheses here using the biogeographic distributional patterns of dragonflies in interfluve areas of the Amazonian biome and also evaluate how differences among in dispersal capabilities between the Anisoptera and Zygoptera suborders may contribute to those patterns. We used distributional information of 392 odonate species in the Amazonian forest in a cladistic analysis of distributions and endemism and the estimated faunistic similarity among interfluves with the Sorensen index. The environmental similarity among interfluves was analysed by discriminant analysis based on eight environmental metrics. Different metrics for geographic distance (connectivity) among interfluves were evaluated and their relation to the other variables tested by the Mantel test. The number of endemic species was linearly correlated to the area of the interfluves. General endemism patterns showed consistent resemblance to those reported for vertebrates, especially the similarity among the Rondônia and Inambari interfluves. Geographical distance has no predictive value for dragonflies distribution, but the environmental similarity is a good predictor of proportion of shared species. The low dispersal group (Zygoptera) presented more clear patterns of distribution and a lower proportion of shared species among different interfluves. The environmental similarity can be considered the determinant factor of the distribution of dragonflies, possibly due to environmental specificity evolved during a long history of some clades in this system. The low dispersal group (Zygoptera) retained more biogeographical information about possible historical factors that determine current distribution. Also, the transport of larvae by macrophyte banks, the lateral change of river courses, the reversal of the drainage basin, together with the capacity to disperse across rivers for some species may be explanations for the lack of effect of isolation by rivers, especially for Anisoptera.

Composição e riqueza de Odonata (Insecta) em riachos com diferentes níveis de conservação em um ecótone Cerrado-Floresta Amazônica

The removal or substitution of riparian vegetation causes disturbance in physical environment, seasonal water flow and water chemical quality. These modifications can cause decrease in species richness by local extinctions. The aim of this study was to examine the effect of disturbance in the physical environmental on the richness and species composition of Odonata adults in streams with different levels of conservation in the river Suia-Missu basin, Mato Grosso, Brazil. Modifications in the aquatic systems affected the Odonata community, probably because their ecophysiological and behavioral requirements of adults and larvae. Anisoptera species, which require sunny environments because of their body size, had higher species richness in environments with low plant cover. On the other hand, Zygoptera species, which generally inhabit streams with dense vegetation, presented a decrease in richness in disturbed environments, as a result high sunlight radiation and/or variations in temperature. Hence, in both suborders, environmental perturbations do not need to be severe to change species composition, indicating that ecosystem services could be lost, even with only partial alterations in physical environment.