Identifying Shifts in Leaf-Litter Ant Assemblages (Hymenoptera: Formicidae) across Ecosystem Boundaries Using Multiple Sampling Methods

Abstract

Global or regional environmental changes in climate or land use have been increasingly implied in shifts in boundaries (ecotones) between adjacent ecosystems such as beech or oak-dominated forests and forest-steppe ecotones that frequently co-occur near the southern range limits of deciduous forest biome in Europe. Yet, our ability to detect changes in biological communities across these ecosystems, or to understand their environmental drivers, can be hampered when different sampling methods are required to characterize biological communities of the adjacent but ecologically different ecosystems. Ants (Hymenoptera: Formicidae) have been shown to be particularly sensitive to changes in temperature and vegetation and they require different sampling methods in closed vs. open habitats. We compared ant assemblages of closed-forests (beech- or oak-dominated) and open forest-steppe habitats in southwestern Carpathians using methods for closed-forest (litter sifting) and open habitats (pitfall trapping), and developed an integrated sampling approach to characterize changes in ant assemblages across these adjacent ecosystems. Using both methods, we collected 5,328 individual ant workers from 28 species. Neither method represented ant communities completely, but pitfall trapping accounted for more species (24) than litter sifting (16). Although pitfall trapping characterized differences in species richness and composition among the ecosystems better, with beech forest being most species poor and ecotone most species rich, litter sifting was more successful in identifying characteristic litter-dwelling species in oak-dominated forest. The integrated sampling approach using both methods yielded more accurate characterization of species richness and composition, and particularly so in species-rich forest-steppe habitat where the combined sample identified significantly higher number of species compared to either of the two methods on their own. Thus, an integrated sampling approach should be used to fully characterize changes in ant assemblages across ecosystem boundaries, or with vegetation change over time, and particularly so in species-rich habitats such as forest-steppe ecotones.

How estimated ant diversity is biased by the sampling method? A case study of Crete: a Mediterranean biodiversity hotspot

“…The results of this study underline that the outcome of taxonomic inventory or estimation of functional composition and diversity depends on selected sampling methods (Wiezik et al 2015;Lee and Guénard 2019). In our opinion, relying on a single method can strongly bias obtained results (see Wiezik et al 2015;Hanisch et al 2018). Thus, we recommend using an integrated approach that includes several complementary methods suitable for the studied habitat, especially when a survey aims to assess a-, b-, and cdiversity.…”

“…Pitfall traps can be used only in localities with well-developed soil or litter layer, and they detect only a particular group of ants (Romero and Jaffe 1989;Sheikh et al 2018). This method seems to be insufficient in rocky, steep, or flooded areas and is not applicable in anthropogenic habitats (Gotelli et al 2011;Wiezik et al 2015). PTM requires also revisiting the same sampling area.…”

“…The majority of surveys focused on examining the efficiency of selected sampling methods in biodiversity surveys were conducted in tropical habitats (Donoso and Ramon 2009; Higgins and Lindgren 2012; Wiezik et al 2015;Wong and Guénard 2017;Hanisch et al 2018;Lee and Guénard 2019;Longino et al 2019), since these habitats host the highest levels of terrestrial biodiversity around the globe. Less numerous reports come from the temperate zone (King and Porter 2005;Schlick-Steiner et al 2006;Ellison et al 2007;Lessard et al 2007).…”

Karstic Microrefugia Host Functionally Specific Ant Assemblages

“…We found that the number of ant species associated primarily with forest habitats (e.g., F. truncorum, M. ruginodis, and L. platythorax) was the highest in grassland dolines, whereas only one species (M. ruginodis) with few occurrences was observed in forested sites. In Central Europe, Fagus sylvatica forests with lowresource availability are among the most species poor habitats, usually with only a few ant species and very low population densities (Dolek et al, 2009;Wiezik et al, 2015). In our previous study (Bátori et al, 2019), we detected a significant effect of slope exposure on ant species composition within the grassland dolines in the Bükk Mts (e.g., M. ruginodis dominated the north-facing slopes).…”

“…For instance, the presence of grassland patches in forested landscapes may support the maintenance of high ant diversity and facilitates the persistence of several species that cannot survive in shady habitats (Dolek et al, 2009). In contrast, homogenous habitats (e.g., Fagus sylvatica forests with low resource availability) create unfavourable conditions for many ants (Dolek et al, 2009;Wiezik et al, 2015). Results of the abovementioned studies suggest that habitat heterogeneity and related vegetation patterns may influence the composition of ant assemblages in current and potential microrefugia by filtering their functional traits, resulting in a relationship between the functional diversity of assemblages and small-scale environmental conditions (cf.…”