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Semi-natural farming systems with high conservation value offer a valuable opportunity to meet biodiversity conservation goals without compromising agricultural production. The high conservation value of such systems often roots in their increased local or landscape-level heterogeneity, which facilitates the coexistence of different species on a small spatial scale. Gaining a comprehensive understanding of the coexistence mechanisms operating in such systems is essential to mark future conservation trajectories. To facilitate this process, in this study, we aimed to uncover the interactive effects of spatial and temporal heterogeneity on community structuring mechanisms in wood-pastures, Europe’s widespread and heterogeneous semi-natural land-use form. Using ants as bioindicators, we connected species occurrence data with fine-scale measurements of local microclimatic conditions and quantified the seasonal niche breadths and overlaps of ant species forming communities in the four different habitat types (grasslands, solitary trees, forests, and forest edges) of three Central European wood-pastures. The niche quantification (performed for 28 ant species in total) was based on four-dimensional hypervolumes, with solar irradiation, air and soil temperature, and air humidity values of every species occurrence. Our results show that despite being located close to one another, the ant communities of the four different habitat types exhibited distinct patterns of seasonal realized niche dynamics, leading to community-wide temporal changes in niche hypervolumes and hypervolume overlaps (i.e., realized niche breadths and niche overlaps). The hypervolumes of dominant ants (characterized by high behavioral and ecological dominance) were mainly determined by the favorability of environmental conditions throughout the year, and in turn, their values shaped the realized niche breadths and overlap patterns of the intermediate and subordinate species. Importantly, the niche expansions and retractions of the dominant group changed the competitive pressure within the communities (quantified by hypervolume overlaps), opening up empty ecological niches to intermediate and subordinate species during periods characterized by suboptimal environmental conditions. Moreover, the niche dynamics showed a varying pattern across the different habitat types, implying that habitat structure and the associated environmental conditions interact with the effects of seasonality even on a small spatial scale. Our results uncover the interactive effects of spatial and temporal heterogeneity on coexistence mechanisms within wood-pastures. Given the distinct patterns in community dynamics and different community structuring mechanisms of the individual habitat types, wood-pastures and other complex landscapes have the potential to sustain different communities on a small spatial scale and thus boost landscape-level biodiversity.

Due to the intensified land use in transformed landscapes, grassland biodiversity is often restricted to habitat fragments inadequate for arable use or for urban development. In continental parts of Eurasia, the ~600,000 ancient burial mounds (called “kurgans”) built by nomadic tribes of the steppes are amongst the most widespread landmarks providing refuge for dry grassland species. In our study by using plant functional groups and functional traits, we aimed at gaining insight into the ecological and evolutionary processes shaping the structure and the composition of assemblages of grassland specialist plant species on kurgans embedded in the agricultural landscapes of East-Hungary. As a comparison, we also studied roadside verges and pristine extensive grasslands in the same region. We found that despite their small size, due to the lack of human disturbances and high microhabitat diversity kurgans can maintain a high species richness and percentage cover of specialists, especially when compared to verges. We revealed that assemblages of specialist plants on kurgans are characterized by traits typical to terrestrial habitat islands such as self-compatibility, large seed mass and tall stature. Kurgans and extensive grasslands were characterized by higher functional diversity (both at the level of single traits and multi-trait based functional dispersion) which is probably due to the higher level of environmental heterogeneity compared to the homogeneous environment in verges.

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.

Dolines are local depressions of karst surfaces. They can be considered potential microrefugia for various species. We investigated the species composition and vegetation pattern of two medium-sized dolines in Hungary before and 10 years after logging, and analysed how different species groups (oak forest species, beech and ravine forest species and disturbance-tolerant species) were affected. The cover and number of oak forest species and disturbance-tolerant species increased, while the cover and number of beech and ravine forest species decreased within dolines due to logging. Therefore, their species composition and vegetation pattern have changed substantially, and dolines have partially lost their capacity to act as safe havens for plant species adapted to cooler conditions.