A comparison of the efficiency of sampling methods beetles (Insecta: Coleoptera) Shast-kalateh beech forest, Golestan Province

Insects are one of the most important biomass components in a forest ecosystem and estimating their species richness is very important which can provide a suitable perspective for assessing the biodiversity of forest ecosystems. The present study has compared three methods of collecting some beetles in one of the northern beech forests of Iran (Golestan Province). For this purpose, 12 plots were selected, and beside direct sampling, one window and two pitfall traps were installed in each plot. Based on the results of three sampling methods, a total of 3341 specimens from 226 species were collected of Coleoptera order, including 635 specimens in direct sampling, 694 specimens in the pitfall traps and 2012 specimens in the window traps. Species richness in the window traps increased at a higher rate in comparison to the other methods. The results of non-metric multidimensional scaling (NMDS) showed that the species composition in each sampling methods is significantly different. Considering the Venn diagram of 226 identified species, out of a total of 3341 specimens, 22 species were common in the three sampling methods but 93, 39 and 23 species were caught only in the window trap, pitfall trap and direct sampling, respectively. In the present study, Scraptia sp. from the family Scraptiidae was recognized as an undescribed species in window trap. Additionally, the indicator species of pitfall traps, direct sampling and window traps with highest index value of 0.7544, 0.5000, and 0.7500 were Geotrupes spiniger (Scarabaeidae), Uleiota planata (Silvanidae) and Megathous menentriesi (Elateridae), respectively