Response of ground-dwelling harvestman assemblages (Arachnida: Opiliones) to European beech forest canopy cover

Abstract

Abstract.We studied the effects of the overstory canopy cover on ground-dwelling harvestmen communities in European beech forests in the Western Carpathian Mts. We analyzed the differences in species richness, abundance and composition in two tree canopy cover categories (closed and open canopy). Overall, 1765 individuals belonging to 16 species were caught using pitfall traps. Repeated-measures ANOVA revealed that under both closed and open canopies a similar absolute and rarefi ed species richness and number of individuals (standardized to 100 pitfall trap days) were caught, and that both species richness and abundance were affected by the season (i.e., time of trap replacement); yet the total number of individuals trapped was more than two times greater under the open canopy than under the closed canopy. Despite the subtle differences in the taxonomic composition of the catches under the open and closed canopies revealed by DCA followed by RDA, the composition of ground-dwelling harvestmen assemblages differed under the two canopy covers. The open canopy was more suitable for heliophilic, xerothermic eurytopic harvestmen species typical for open and ecotonal habitats, such as Egaenus convexus (C.L. Koch) and Oligolophus tridens (C.L. Koch) but still suitable for hemihygrophilic Lophopilio palpinalis (Herbst). The closed canopy stands were preferred by shade-tolerant, hygrophilic eurytopic harvestmen species, such as Trogulus sp. Latreille, Dicranolasma scabrum (Herbst) and Platybunus bucephalus (C.L. Koch). Our results highlight the importance of intra-habitat heterogeneity of a harvestmen community.

Marked compositional changes in harvestmen assemblages in Amazonian forest islands induced by a mega dam

“…According to several other studies, the diversity of harvestmen recorded on the islands was low (Pinto‐da‐Rocha & Bonaldo, ; Bonaldo et al ., ; Tourinho et al ., ; ; Colmenares et al ., ; Porto et al ., ). The small number of species detected per island also reinforces diversity impoverishment in forest fragments, as suggested for the Atlantic Forest (Bragagnolo et al ., ) and temperate forests (Černecká et al, ; Mihál & Černecká, ). Indeed, more than half of the sampled islands exhibited only one to five species, whereas mainland sites retained 11–20 species, exhibiting a similar pattern obtained in other Amazonian sites (; Bonaldo et al, ; Tourinho et al ., ; ; ; Porto et al ., ).…”

“…Despite the significant ecological importance of harvestmen (Fig. ), serving as excellent predictors of environmental quality given their rapid responses to habitat change and fragmentation (Bragagnolo et al ., ; Černecká et al ., ), this charismatic taxonomic group remains poorly investigated in tropical fragmented forest landscapes. Considering that fragmentation is a landscape‐scale process (Fahrig, ), studies assessing the responses of harvestmen communities to forest fragmentation should explicitly consider the influence of landscape variables.…”

“…Although few studies have shown the negative impacts of fragmented forest habitats on harvestmen assemblages in temperate forests (Černecká et al ., ; Mihál & Černecká, ), only one study to date – conducted in forest patches embedded within heterogeneous vegetation matrices in the Brazilian Atlantic forest – has assessed the effects of forest fragmentation on harvestmen within a tropical forest landscape (Bragagnolo et al ., ). In this study, harvestmen assemblages were more clearly structured by forest quality and size than other arthropod taxa, suggesting that they are good community‐wide indicators of intermediate‐level disturbances and can be used as a robust model to monitor tropical forest disturbance.…”

The effect of canopy openness of European beech (Fagus sylvatica) forests on ground‐dwelling spider communities

“…An opening in the forest canopy has been found to be the major driver of ground‐dwelling invertebrate community structure (Richardson et al ., ; Seibold et al ., ,b; Thorn et al ., ; Perry et al ., ). Canopy gaps have been found to have a positive impact on the species richness of carabids (Seibold et al ., ), myriapods‐isopods (Spitzer et al ., ) and hoverflies (Gittings et al ., ), and the negative effect of a disturbed canopy layer has been observed on the abundance of springtails (Seibold et al ., ) and beetles (Gandhi et al ., ; Seibold et al ., ,b); in addition, no effect of canopy gaps on species richness of harvestmen has also been observed (Černecká et al ., ). The observed inconsistency in the pattern of effects of canopy openness (canopy cover) on invertebrate abundance and richness can be explained by different habitat requirements of specific taxa and by the range of the studied gradient of the canopy openness (Seibold et al ., ; Perry et al ., ).…”

“…These positively affect spatio‐temporal heterogeneity at various spatial scales (Frelich, ). The impacts of forest canopy disturbances interact with forest communities, including ground‐dwelling invertebrates (Entling et al ., ; Seibold et al ., ; Černecká et al ., ; Perry & Herms , ; Perry et al ., ).…”