Effects of marginal vegetation removal on Odonata communities

Abstract

Aim: Here we assess the effects of habitat degradation on individuals of the two suborders of Odonata community of Borecaia river sub-basin. More specifically, we tested the hypothesis that Anisoptera richness would be positively affected by removal of vegetation; on the other hand, Zygoptera richness would be adversely affected by virtue of their ecophysiological requirements; Methods: We selected 10 streams of similar orders, six preserved and four degraded. Streams characterized as preserved had values of Index of Habitat Integrity (HII) above 0.70 (0.77 ± 0.07, mean ± SD) and continuous forest on both sides with a minimum width of 70 meters. Each site was sampled three times on different days. The effect of vegetation removal on richness was assessed using richness estimated by first order Jackknife; Results: Decreased physical integrity (measured with IIH) of streams had no significant effect on the estimated richness to Odonata in general. However, the estimated richness of Anisoptera showed an inverse relationship with the integrity (r 2 = 0.485, P = 0.025), i.e., there was a reduction in their species richness with increasing integrity; Discussion: As a general pattern, Anisoptera presents higher richness in an altered site; on the other hand, Zygoptera presents higher richness in a preserved one. This pattern suggests that Odonata needs to be considered at the sub-order level to access the effects of habitat degradation on these insects. Because of its restrictions ecophysiological Odonata varied widely in their composition and species richness between the two types of environments, it reinforces the potential of the order of studies and environmental monitoring also shows that Zygoptera be more affected by changes in habitat. However, further studies including more samples and different streams are need to confirm this pattern, being an interesting line of research for future works.Keywords: environmental integrity, Anisoptera, Zygoptera, species richness, environmental changes. Resumo: Objetivos:Com o intuito de avaliar os efeitos de mudanças na integridade ambiental sobre os indivíduos da comunidade de Odonata da sub-bacia do rio Borecaia, testamos a hipótese de que a riqueza de Anisoptera seria afetada positivamente pela remoção da vegetação; por outro lado, a riqueza Zygoptera seria prejudicada em virtude de suas necessidades ecofisiológicas; Métodos: Selecionamos 10 riachos de ordens similares, seis classificados como preservados e quatro como alterados. Riachos classificados como preservados apresentaram valores do Índice valores de Integridade Habitat (HII) acima de 0.70 e mata continua nas duas margens com uma largura mínima de 70 metros. Cada ponto foi amostrado três vezes em dias diferentes. O efeito de remoção de vegetação sobre a riqueza foi avaliada utilizando Jackknife de primeira ordem; Resultados: A diminuição da integridade física (mensurada com o IIH) dos córregos não exerceu efeito significativo sobre a riqueza estimada para a Ordem Odonata. Porém, a riqueza estimada de Ani...

Preliminary dragonfly (Odonata) species list from the Pampa biome in Rio Grande do Sul, Brazil, with ecological notes for 19 new records for the State

“…plant diversity) and water quality (e.g., Argia, Homeoura, Oxyagrion) as stated by Garrison et al (2010). Second, in well preserved areas or large forested areas, higher number of Zygopterans such as Heteragrionidae, Calopterygidae and again coenagrionids are expected to be found, many of which have specific environmental restrictions and ecological needs, mostly regarding to diversity of plants and vegetal structures in the riparian areas (Juen et al 2014, Carvalho et al 2013). This fact can explain the occurrence of Minagrion waltheri (Coenagrionidae) in only one locality in SA, which is a well-preserved area that keeps its natural features, as well crystal clear water and high diversity of aquatic/riparian vegetation (Figure 2a).…”

List of Odonates from the Floresta Nacional de São Francisco de Paula (FLONA - SFP), with two new distribution records for Rio Grande do Sul, Brazil

“…In most preserved areas or bigger forested areas it is expected to find a bigger number of Calopterygids and Heteragrionids, which have more environmental restrictions and ecological needs to occur (Carvalho et al 2013).…”

“…The only species known to be widespread in South America is Libellula herculea (Garrison et al 2006). According to Carle & Kjer (2002) this genus is well diagnosed and is considered a sister group of Orthemis, however an undescribed species is known from Brazil (Garrison et al 2006). The two species belonging to the genus Libellula recorded here are: Libellula herculea and Libellula sp.…”

The effects of environmental integrity on the diversity of mayflies, Leptophlebiidae (Ephemeroptera), in tropical streams of the Brazilian Cerrado

“…In general, the loss of environmental quality tends to make habitats more homogeneous, which may have consequences such as the loss of species richness, the modification of species composition, and shifts in abundance patterns (Castello, 2008;Axelsson et al, 2011;Dolny´et al, 2012;Carvalho et al, 2013;Ligeiro et al, 2013;Suga and Tanaka, 2013;Wahl et al, 2013). Ultimately, this process may alter the distribution of the more sensitive species (Souza et al, 2011;Monteiro Ju´nior et al, 2013).…”