Red wood ants are keystone species of forest ecosystems in Europe. Environmental factors and habitat characteristics affect the size of their nest mounds, an important trait being in concordance with ...a colony’s well-being and impact on its surroundings. In this study, we investigated the effect of large-scale (latitude and altitude) and small-scale environmental factors (e.g., characteristics of the forest) on the size of nest mounds of Formica polyctena in Central Europe. We predicted that the change in nest size is in accordance with Bergmann’s rule that states that the body size of endotherm animals increases with the higher latitude and/or altitude. We found that the size of nests increased along the latitudinal gradient in accordance with Bergmann’s rule. The irradiation was the most important factor responsible for the changes in nest size, but temperature and local factors, like the perimeter of the trees and their distance from the nest, were also involved. Considering our results, we can better understand the long-term effects and consequences of the fast-changing environmental factors on this ecologically important group. This knowledge can contribute to the planning of forest management tactics in concordance with the assurance of the long-term survival of red wood ants.
In the face of global pollinator decline, extensively managed grasslands play an important role in supporting stable pollinator communities. However, different types of extensive management may ...promote particular plant species and thus particular functional traits. As the functional traits of flowering plant species (e.g., flower size and shape) in a habitat help determine the identity and frequency of pollinator visitors, they can also influence the structures of plant−pollinator interaction networks (i.e., pollination networks). The aim of this study was to examine how the type of low‐intensity traditional management influences plant and pollinator composition, the structure of plant−pollinator interactions, and their mediation by floral and insect functional traits. Specifically, we compared mown wooded meadows to grazed alvar pastures in western Estonia. We found that both management types fostered equal diversity of plants and pollinators, and overlapping, though still distinct, plant and pollinator compositions. Wooded meadow pollination networks had significantly higher connectance and specialization, while alvar pasture networks achieved higher interaction diversity at a standardized sampling of interactions. Pollinators with small body sizes and short proboscis lengths were more specialized in their preference for particular plant species and the specialization of individual pollinators was higher in alvar pastures than in wooded meadows. All in all, the two management types promoted diverse plant and pollinator communities, which enabled the development of equally even and nested pollination networks. The same generalist plant and pollinator species were important for the pollination networks of both wooded meadows and alvar pastures; however, they were complemented by management‐specific species, which accounted for differences in network structure. Therefore, the implementation of both management types in the same landscape helps to maintain high species and interaction diversity.
We studied whether mown and grazed grasslands have different pollination network structures. We found higher network‐level connectance and specialization in mown sites and higher network‐level interaction diversity in the grazed sites. The same generalist plants and pollinators were important for the pollination networks of both mown and grazed sites; however, they were complemented by management‐specific species, which accounted for differences in network structure.
The consequences of anthropogenic climate change are one of the major concerns of conservation biology. A cascade of negative effects is expected to affect various ecosystems, one of which is Central ...European coniferous forests and their unique biota. These coniferous forests are the primary habitat of many forest specialist species such as red wood ants. Climate change-induced rising of temperature allows trees to skip winter hibernation, making them more vulnerable to storms that cause wind felling, and in turn, promotes bark beetle infestations that results in unscheduled clear-cuttings. Red wood ants can also be exposed to such habitat changes. We investigated the effects of bark beetle-induced clear-cutting and the absence of coniferous trees on colonies of Formica polyctena, including a mixed-coniferous forest as a reference. Our aim was to investigate how these habitat features affect the nest characteristics and nesting habits of F. polyctena. Our results indicate that, in the absence of conifers, F. polyctena tend to use different alternatives for nest material, colony structure, and food sources. However, the vitality of F. polyctena colonies significantly decreased (smaller nest mound volumes). Our study highlights the ecological flexibility of this forest specialist and its potential to survive under extreme conditions.
Karst landscapes are among the topographically most complex systems with various microhabitats, where species can persist despite unfavourable macro-environmental changes. These microhabitats can ...also function as stepping stones during range shifts. Although the enclosed depressions (dolines, sinkholes or tiankengs) of karst landscapes may act as such safe havens, data on the functional diversity of their animal assemblages are scarce. Here, we investigate the functional diversity (i.e., certain functional groups and functional traits) of ant assemblages in dolines and study whether dolines surrounded by resource-poor environments (i.e ., Fagus sylvatica forests) may function as safe havens for different kinds of ants. We found that dolines have the potential to maintain distinctive ant assemblages characterised by specific functional groups and traits that are rare in the surrounding habitats. Although continuous Fagus sylvatica cover in dolines had a detrimental impact on ant assemblages, grassland dolines surrounded by grasslands or Fagus sylvatica forests supported the presence of some specific functional groups and traits. These results suggest that conservation management needs to consider the influence of vegetation characteristics not only in dolines but also on the surrounding plateau. Moderate grazing and/or mowing would be desirable in order to prevent shrub encroachment into grasslands to ensure optimal vegetation structure for ants in the long run. Therefore, proper management and conservation of these safe havens may mitigate the rate of biodiversity loss under global warming. There is a need to explore a wide variety of taxonomic groups and taxon-specific traits in parallel with the quality of the surrounding habitats when evaluating current and potential microrefugia.
Fine-scale topographic complexity creates important microclimates that can facilitate species to grow outside their main distributional range and increase biodiversity locally. Enclosed depressions ...in karst landscapes ('dolines') are topographically complex environments which produce microclimates that are drier and warmer (equator-facing slopes) and cooler and moister (pole-facing slopes and depression bottoms) than the surrounding climate. We show that the distribution patterns of functional groups for organisms in two different phyla, Arthropoda (ants) and Tracheophyta (vascular plants), mirror this variation of microclimate. We found that north-facing slopes and bottoms of solution dolines in northern Hungary provided key habitats for ant and plant species associated with cooler and/or moister conditions. Contrarily, south-facing slopes of dolines provided key habitats for species associated with warmer and/or drier conditions. Species occurring on the surrounding plateau were associated with intermediate conditions. We conclude that karst dolines provide a diversity of microclimatic habitats that may facilitate the persistence of taxa with diverse environmental preferences, indicating these dolines to be potential safe havens for multiple phyla under local and global climate oscillations.
Karst area covers 20% of the earth’s terrestrial surface. Dissolution processes on limestone surfaces contributed to the formation of the karst surface and subsurface features such as caves, ...limestone pavements, valleys, and enclosed depressions (dolines, sinkholes or tiankengs). Karst areas provide important ecosystem services one of which is the habitat function. Karst depressions (dolines) due to their topographically intricate features and microclimatic inversions may support several habitats where species composition and diversity vary with environmental heterogeneity. Dolines may have the potential to act as safe havens for a high diversity of valuable species. However, nowadays these important doline habitats are altered by various man-made activities that made them highly vulnerable and prone to degradation.Topographic parameters (e.g., geometry, size, and slope aspect) and related environmental conditions (e.g., air temperature, air humidity and soil moisture) which contributed to heterogeneity of doline habitats are known to play a major role in determining their biodiversity patterns. These topographic and biological attributes can create microhabitats with unique microclimates which species may depend on for their survival. Microhabitats may be warmer, drier, cooler and/or moister than the prevailing regional climate. As such, they create a mosaic of microclimates that can allow species to survive changes in their environment by migrating short distances between these microhabitats. These fine-scale mosaics improve species’ chances also to persist in a certain landscape. Various studies have shown that dolines may provide microhabitats for unique species that are rare or absent from the surrounding landscape. The heterogenous habitats of dolines may serve as refuges (for decades) or refugia (for millennia) for vulnerable taxa, such as endemic, montane, and relict species. Many of these species can be under threat because of global warming and anthropogenic activities.Dolines have been cultivated extensively, providing sites for various traditional activities such as arable farming, gardening, pasturing and water extraction. The degradation of dolines is among the most pressing issue in karst environments worldwide. Human-induced activities may compromise the capacity of dolines to act as safe havens for species during future climate oscillations, and, as a result, may also reduce the naturalness of their habitats.In Hungary, for centuries, intensive deforestation and grazing drastically have been affecting doline habitats.In our studies, ants and plants were selected as focal taxa because ant colonies and plants share many similarities. Both groups usually ‘nest’ in or on the ground and use their modules (e.g., plant roots and ant workers) to forage in the surrounding habitat. In addition, due to the relatively fixed location of ant colonies and plants, competition in both groups is confined to well-defined zones. Similarities also exist in terms of their functional roles (e.g., subordinate, specialist, and cryptic species). Also, ant foundresses (i.e., colony-founding queens) can be considered analogous to dispersing plant seeds. Ants are particularly sensitive to changes in resources, moisture, and temperature, which makes them good indicators of environmental changes, ecosystem health and functioning. Generally, the species richness of ants is positively associated with habitat diversity, which may also affect the functional diversity of their assemblages. Topographically complex areas may contain a higher diversity of microhabitats providing suitable nesting sites and a higher amount of exploitable resources for different functional groups of ants. Plants have long been recognized as bioindicators and can indicate the naturalness of their habitat. The approach of naturalness indicator values is like the original Ellenberg-type indicator values and has been used successfully to study disturbance. Some species indicate disturbed sites, while others prefer less disturbed or natural habitats. For instance, the presence of many endemics, habitat specialists and endangered species within a habitat may indicate higher naturalness and higher conservation value.
Karst depressions (dolines) have the potential to act as safe havens for a high diversity of valuable species. We showed that local anthropogenic disturbances play a significant role in determining ...the naturalness of dolines. We compared the number of specialist species, competitor species, generalist species and species of disturbed habitats between natural and disturbed dolines in two Hungarian karst areas, where different types of anthropogenic disturbances have been shaping the vegetation for centuries. We found that these disturbances have the potential to negatively influence the naturalness of dolines, reducing the number of valuable species, thus affecting the conservation value of dolines. To maintain the naturalness of vegetation in these doline habitats, the populations of ruderal competitors should be eliminated, and sustainable forest management should be adapted. However, there are still open questions about the effects of different disturbances on the naturalness in dolines that need to be answered to determine which conservation strategies will be particularly suitable for valuable species in a warming climate.
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