Werner Ulrich

The ongoing global decline in insect abundance and biomass is now well documented. To what degree this decline in insect abundance and biomass causes losses in biodiversity is still unclear, mainly due to the lack of appropriate quantitative long-term studies that allow for precise estimates of richness over time. In conservation ecology, the species accumulation curve (SAC) is a common method to assess the effectiveness of protected areas and to compare richness estimates at a standardised sample size. However, extrapolation and richness estimation are only possible in cases of asymptotic convergence, which was not achieved in many studies. Here, we construct temporal series of SACs from long-term surveys (1950–2022) of Austrian butterflies and macro-moths to assess temporal trends in species richness and dominance inside and outside protected areas across an altitudinal gradient. Irrespective of altitude, we detected a trend towards increasing rarity and dominance outside PAs, but not towards decreasing total richness. These trends were less visible inside PAs, although in lowland PAs sample-size-normalised richness also decreased over time. Evenness in PAs remained constant over time and was generally higher than outside PAs. Both, protected and unprotected areas suffered from high temporal species turnover. We conclude that the Lepidoptera assemblages of our study region underwent severe and ongoing structural rearrangements with unknown consequences for the sustained occurrence of many now-rare species. Temporal series of spatial species accumulation curves are able to detect such structural changes. The protected areas of our study region succeeded in conserving assemblage structure and compositional variability. Fewer species than outside PAs became rare. However, total richness is still higher outside PAs, and negative population trends were also visible inside PAs.

The ongoing global decline in insect abundance and biomass is now well documented. To what degree this decline in insect abundance and biomass causes losses in biodiversity is still unclear, mainly due to the lack of appropriate quantitative long-term studies that allow for precise estimates of richness over time. In conservation ecology, the species accumulation curve (SAC) is a common method to assess the effectiveness of protected areas and to compare richness estimates at a standardised sample size. However, extrapolation and richness estimation are only possible in cases of asymptotic convergence, which was not achieved in many studies. Here, we construct temporal series of SACs from long-term surveys (1950–2022) of Austrian butterflies and macro-moths to assess temporal trends in species richness and dominance inside and outside protected areas across an altitudinal gradient. Irrespective of altitude, we detected a trend towards increasing rarity and dominance outside PAs, but not towards decreasing total richness. These trends were less visible inside PAs, although in lowland PAs sample-size-normalised richness also decreased over time. Evenness in PAs remained constant over time and was generally higher than outside PAs. Both, protected and unprotected areas suffered from high temporal species turnover. We conclude that the Lepidoptera assemblages of our study region underwent severe and ongoing structural rearrangements with unknown consequences for the sustained occurrence of many now-rare species. Temporal series of spatial species accumulation curves are able to detect such structural changes. The protected areas of our study region succeeded in conserving assemblage structure and compositional variability. Fewer species than outside PAs became rare. However, total richness is still higher outside PAs, and negative population trends were also visible inside PAs.

The concept of space–time equivalence refers to the observation that ecological patterns might look similar when studied in space or time. It has frequently been applied in studies on environmental (mainly climate) change, where appropriate temporal data are lacking. Here, we take advantage of long-term butterfly museum records, taken from 1985 to 2022 at multiple sites from three habitat types in the northern Austrian Alps. We ask whether the pattern of species accumulation, the demographic variability, and the temporal pattern of species turnover (β-diversity) of butterflies are qualitatively and also quantitatively equivalent in space and time. A power function model of species accumulation was able to describe the long-term temporal and large-scale spatial variability of butterfly assemblages. Slopes of the species accumulation curves and β-diversity were always higher in space than in time. Average species ranks of the most frequently occurring species in space were consistently higher than those in time. Both patterns were most pronounced in ecologically more specialised species and in pastures. We conclude that habitat characteristics and heterogeneity are more important for the degree of β-diversity than species traits. We predict that increasing spatial faunal homogenisation should shift butterfly and also other arthropod assemblages towards patterns of species accumulation with similar slopes.

Polish Journal of Ecology publishes research covering major aspects of ecology, including behavioural, conservation, ecosystem, evolutionary, functional, landscape, molecular, physiological, population, trophic ecology and new methods for ecological research without bias toward particular taxa or geographic regions.

The European Biodiversity Strategy for 2030 targets on 30% of protected areas (PAs). As many larger PAs were erected with respect to vegetation or vertebrates, their value for insect protection remains disputed. Comparative studies on PA effectiveness for insect assemblages are surprisingly rare. Here, we focus on butterflies and macro-moths (Lepidoptera) because they are taxonomically well-resolved and commonly used as bioindicators. We ask 1) whether larger PAs are able to safeguard and stabilise assemblage structures in comparison to adjacent unprotected areas and 2) how assemblages developed inside and outside protected areas since PA erection? We use 295,477 records from 1,595 butterflies ad macro-moth species recorded inside and outside of 45 PAs in the Federal State of Salzburg (Austria) from 1950 to 2022. The PAs tended to be more species rich than the surrounding areas, but did not accumulate otherwise rare species. PAs and surrounding areas markedly differed in assemblage structure, evenness, and species composition, but not in abundance. Less than 2% of species occurred only inside PAs, while more than ¼ of species studied here were not covered by any of the studied PAs. PAs and surrounding areas tended to become increasingly similar in assemblage composition after PA erection. The underlying faunal exchange points to an effective conservation (PA) area larger than the nominal PA size. Because lowland areas harbour most of the threatened and habitat specialist species we call for the erection of additional PAs at lower altitudes to protect rare and endangered insect species with specific habitat requirements.

Globally, nature reserves and protected areas (PAs) have been designed to conserve valuable ecosystems and wildlife against human‐induced threats. However, to which degree PAs save biodiversity is a matter of intense discussion, mainly based on vertebrate data; extensive assessments for invertebrates are largely lacking. We analysed whether butterfly and macro‐moth (Lepidoptera) diversities and abundances increased in PAs in comparison to the initial state and the surrounding landscape during the last decades. We used long‐term records (1900–2022) of Lepidoptera (butterflies and macro‐moths) in the federal state of Salzburg (northern Austria) and recent Austrian Red List endangerment assignments. Irrespective of elevation, records of rare and endangered species increased inside PAs by about 6%. However, only a few species were responsible for this increase in the number of records while the majority decreased within PAs. The total richness of rare and endangered species inside PAs was constantly lower than outside PAs, even after accounting for unequal sample sizes. Still, the majority of rare and endangered species occurs outside PAs while PAs increasingly harbour non‐threatened species. These results demonstrate a mismatch in the spatial distribution of threatened butterflies and macro‐moths and the localisation of PAs in northern Austria. This mismatch causes an insufficient protection of the insect diversity despite the fact that 20.4% of the study area is strictly protected. We call for a more diversity‐focused designation of PAs that also considers the positive contribution of heterogeneous landscapes.

The current increase in annual temperatures is altering the spatial distribution and timing of activity patterns, i.e. phenology, of many animal and plant species. Theory predicts such phenological plasticity to affect community composition and food web structure. We inferred temporal changes in Lepidoptera phenology in a mountainous region of northern Austria characterised by ongoing environmental and climate change. Long-term records (1960‒2022) representing 189,993 records of 2111 Lepidoptera species at two elevational belts served to assess phenology and species composition at a weekly resolution. Temporal trends towards earlier appearance in spring and prolonged activity in autumn altered short-term community composition at lower and higher elevations. Phenological plasticity was high throughout the study period and increased over the course of the years, becoming more and more fuzzy towards autumn. Variability in community composition decreased over the years. We found little evidence for synchronous phenological shifts at the community level. Species-specific phenological plasticity seems to prevail, causing constant changes in seasonal community composition. Long-term directional changes in community composition due to increasing temperature might change food webs and affect species interactions, particularly pollination, and possibly insect and plant diversity.

The local species abundance distribution (SAD) and the associated distributions of species functional traits (TADs) both result from the process of plant community assembly. Community assembly has been extensively studied for dominant and rare plants, while subordinates, the species of intermediate abundance in a community, have received less research attention although this group is comparatively species rich and important for community functioning. Here, we study the functional role of subordinate species (those covering the intermediate 50% of abundance ranks) using a large data set of Palearctic dry and semi‐dry grassland plant communities and data on specific leaf area, seed mass and plant height. Our findings indicate that species rank orders of SADs and TADs tend to be negatively correlated, causing the TAD to have higher evenness than the associated SAD. Subordinate species represented on average less than 15% of total plant abundance and trait space. Functional diversity of subordinates was lower than expected by a null model that assumed an equiprobable random distribution of trait values among plant species. Climate seasonality and elevation appeared to be the most important drivers of subordinate abundance and functional diversity. We conclude that subordinates differ from dominants in trait composition, leading to their partial functional independence from dominants.

Species abundance distributions (SADs) depict the order of species based on their ranked abundances. While they have been central to much theoretical work in community ecology, their practical value in applied ecology is still debated. Supported by a meta‐analysis of 1153 publications on SADs, we review the state of the art in the practical use of SADs and provide a conceptual framework for the study of SADs in an applied context. Of the studies sourced through the meta‐analysis, only 5% had a truly applied focus; 93% of these studies dealt with the influence of agricultural practices, forest management, pollution or other forms of disturbance on the shape of the SAD. We found little support for previous claims that disturbance shifts species abundance distributions from a lognormal to a steep logseries form. Some species‐rich communities, such as tropical forests, are well fit by a logseries even in the absence of disturbance, and steep, uneven SADs may be more representative of dispersal‐limited communities under neutral dynamics. Policy implications. Further insight into the links between disturbance and species abundance may come from the recognition that the species abundance distribution (SAD) is a special case of a broader concept, the trait abundance distribution (TAD), which can provide indirect information on resource utilisation and niche partitioning. An analysis of the changes in SADs and TADs, together with environmental data, should allow for a better understanding of the assembly and functioning of ecological communities in both applied and basic ecology.