Arthropods in tropical oaks: differences in their spatial distributions within tree crowns

Abstract

The arthropod activity in the upper and the lower zone of nine emergent oak trees (genus Quercus) of a submontane forest in Sabah, Borneo, Malaysia, was investigated by using flight interception traps, yellow colour traps, and arboreal pitfall traps. Number of arthropods did not differ significantly between the upper and the lower region of the tree crowns. Nevertheless, the results reveal significant differences in the abundances of several arthropod groups between the two zones. In the lower part of the oak crowns Homoptera and ants (mostly alates) were sampled in higher numbers, whereas the upper zone was dominated by Diptera and Hymenoptera (ants excluded). Beetles and most other groups showed no significant differences in abundance between the lower and upper zone of the oak trees. Thus, the arthropods of the investigated community are not evenly distributed. The arthropod community in tree crowns, which often has been treated as a homogenous unit, is in fact divided into subunits formed by differently composed arthropod assemblages.

Oak canopy arthropod communities: which factors shape its structure?

“…However, the studies that have examined the stratification of arthropod communities in the canopy of oaks have shown contrasting results. On one hand, some studies have reported that the upper canopy supports the highest density and abundance of arthropods; such is the case of the study by Simmon and Linsenmair (2001), who found that the density of herbivorous insects associated with the canopy of Q. subsericea in a rainforest in Borneo, Malaysia, was greater in the upper canopy compared to the lower canopy, suggesting that in these microenvironments, differences in temperature or in foliar chemistry, and palatability of leaves between layers could be responsible for differences in the density and abundance of the associated arthropod species. In addition, this study found differences in the composition and abundance of the arthropod community between layers; in the lower layer, homoptera and ants were the dominant groups, while at in the upper layer, the dominant groups were diptera and hymenoptera (except ants).…”

“…In addition, plant communities show large spatial differences in richness, genetic diversity, abundance, and total biomass, helping create heterogeneous habitats that promote differences in arthropod communities. In forests, horizontal (between localities, Gering and Crist 2000;Summerville et al 2003a, b) and vertical spatial variation (between layers) can have an influence on canopy insect communities (Le Corff and Marquis 1999;Simmon and Linsenmair 2001;Forkner et al 2004;Barber and Marquis 2009). The horizontal differences can be generated by changes in biotic (i.e., dominant canopy species, composition, abundance, and diversity of host species, forest age) and abiotic factors (i.e., geological age, topography, soil type, altitude) between localities (Gering et al 2003;Price et al 2004).…”

“…This stratification of vegetation results in a great diversity of microhabitats, which can support different communities of arthropods (Parker 1995;Forkner et al 2004;Barber and Marquis 2009). However, there has been no consensus among researchers to define the canopy vertically in temperate forests, as there are some who recognize two layers, overstory (canopy and aerial part), and understory (shrubs and herbaceous plants, Le Corff and Marquis 1999;Lewinsohn et al 2005;Murakami et al 2005) and some who divide the canopy into an upper and a lower layer (Wagner et al 1995;Simmon and Linsenmair 2001). In general, the spatial variation of resources and conditions between locations and layers generates changes in the composition, richness, abundance, and diversity of arthropod communities associated with canopies (Strong et al 1984;Gering et al 2003).…”

Community Composition of Longhorned Beetles (Coleoptera: Cerambycidae) in the Canopy and Understorey of Sugar Maple and White Pine Stands in South-Central Ontario

“…It is possible that we were close to accumulating the maximum richness obtainable by using this single trap type (Longino et al 2002). Multiple sampling methods and extensive effort are required to obtain relatively complete inventories of species-rich arthropod communities (Winchester and Ring 1996, Longino et al 2002, Simon and Linsenmair 2001. However, it is interesting that we recorded a similar number of anthophilous species in 6 wk of sampling as did Bond and Phillip (1999) over a 4-yr period of timed observations in forests and along road edges in southeastern Ohio, despite catching only one-Þfth as many individuals.…”

Effects of Habitat Disturbance can be Subtle Yet Significant: Biodiversity of Hawkmoth-Assemblages (Lepidoptera: Sphingidae) in Southeast-Asia

“…Lawton et al 1998;Schulze et al 2004), and although local diversity for a majority of taxa diminishes with increasing disturbance, reactions of different groups are often quite dissimilar in detail (e.g. termites: Gathorne-Hardy et al 2002, scarabid beetles: Holloway et al 1992chrysomelid beetles: Wagner 1999, leaf litter ants: Bru¨hl 2001 invertebrates: Simon and Linsenmair 2001;Floren et al 2001, vertebrates: Johns 1992Lambert 1992, mantids: Helmkampf et al, in press, butterflies: Hamer et al 1997Fermon et al 2005). Each taxon has certain specific habitat requirements (e.g.…”