Influence of different riparian vegetation widths and substrate types on the communities of larval Odonata (Insecta) in southern Brazilian streams

Mateus Marques Pires,Leonardo Maltchik,Cristina Stenert,Nícolas Felipe Drumm Müller

doi:10.1590/s2179-975x2520

Abstract

Abstract: Aim We assessed the influence of substrate type and categories of riparian vegetation widths on the community structure of Odonata (Insecta) in southern Brazilian streams. Methods Sampling took place in twelve stream reaches differing in their riparian vegetation widths (from more than 40 m up to less than 5 m). Larval odonates were collected in inorganic (stone and gravel) and organic (leaf litter) substrates at each stream reach. Differences in Odonata composition among substrates and categories of riparian vegetation width were tested using PERMANOVA and visualized with ordination diagrams. In addition, we assessed the influence of riparian vegetation width taking into account two levels of resolutions: fine (four categories: > 40 m, 30-15 m, 15-5 m and < 5 m) and coarse (narrower and broader than 15 m). Results Odonata composition differed more strongly according to substrate type regardless of the level of resolution. Organic substrate (litter) had different composition and higher richness than inorganic ones. Odonata composition significantly differed between riparian vegetation widths at the coarser level of resolution (narrower and broader than 15 m); at the coarser level, the interaction between substrate and riparian widths was significant, with the composition from litter substrate in broader widths differing from stone and gravel in narrower widths. Conclusions The composition of odonate larvae responded to the major reductions in riparian widths (above > 15 m), indicating that reductions above this level are enough to affect the community structure of Odonata. Additionally, the different composition of Odonata in organic substrates in broader riparian vegetation widths compared to inorganic substrates in narrower widths indicate a complex relationship between riparian vegetation and substrate in the assembly of insect communities in southern Brazilian forest streams. The interaction between riparian vegetation widths and substrate suggests that the effects of reductions in riparian widths on Odonata composition are not similar across substrate types.

Highlights

The integrity of the riparian vegetation is closely associated with stream biodiversity (Allan & Castillo, 2007)
Aim: We assessed the influence of substrate type and categories of riparian vegetation widths on the community structure of Odonata (Insecta) in southern Brazilian streams
Odonata composition significantly differed between riparian vegetation widths at the coarser level of resolution; at the coarser level, the interaction between substrate and riparian widths was significant, with the composition from litter substrate in broader widths differing from stone and gravel in narrower widths

Summary

Introduction

The integrity of the riparian vegetation is closely associated with stream biodiversity (Allan & Castillo, 2007). Various studies attempted at estimating the widths of riparian vegetation required to minimize negative impacts on stream biodiversity (e.g., Kiffney et al, 2003; Marczak et al, 2010; Valle et al, 2013; Moraes et al, 2014; Braun et al, 2018). A range of responses to modification in riparian widths is reported for different aquatic communities across different ecosystems (Kiffney et al, 2003; Death & Collier, 2010; Lorion & Kennedy, 2009; IñiguezArmijos et al, 2014; Valle et al, 2013; Moraes et al, 2014) This scenario hinders consensus on the establishment of thresholds of riparian vegetation width for detection biodiversity loss (Leal et al, 2018)

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