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Recent losses in the abundance and diversity of arthropods have been documented in many regions and ecosystems. In grasslands, such insect declines are largely attributed to land use, including modern machinery and mowing regimes. However, the effects of different mowing techniques on arthropods remain poorly understood. Using 11 years of data from 111 agricultural grassland plots across Germany, we analyzed the influence of various grassland management variables on the abundance and abundance‐accounted species richness of four arthropod orders: Araneae, Coleoptera, Hemiptera, and Orthoptera. The analysis focused on detailed mowing information, for example, days after mowing and mower type, and compared their effect with other aspects of grassland management, that is, rolling, leveling, fertilization, and grazing. We found strong negative effects of mowing on all four arthropod orders, with arthropod abundance being lowest directly after mowing and steadily increasing to three to seven times the abundance after 100 days post‐mowing. Likewise, Hemiptera and Coleoptera species richness was 30% higher 100 days after mowing. Mower width showed a positive effect on Orthoptera abundance, but not on the other arthropods. Arthropod abundance and Coleoptera species richness were lowest when a mulcher was used compared to rotary or bar mowers. In addition to mowing, intensive grazing negatively affected Orthoptera abundance but not the other orders. Mowing represents a highly disturbing and iterative stressor with negative effects on arthropod abundance and diversity, likely contributed by mowing‐induced mortality and habitat alteration. While modifications of mowing techniques such as mower type or mowing height and width may help to reduce the negative impact of mowing on arthropods, our results show that mowing itself has the most substantial negative effect. Based on our results, we suggest that reduced mowing frequency, omission of mowing in parts of the grassland (refuges), or extensive grazing instead of mowing have the greatest potential to promote arthropod populations. [ABSTRACT FROM AUTHOR]

Urban areas have profound impacts on local species diversity and composition through a set of intertwined changes in the environment. As the world is rapidly urbanising while simultaneously facing a biodiversity crisis, a better understanding of how urbanisation influences biodiversity is necessary.To test if and how urbanisation influences moth diversity and whether urbanisation is acting directly or indirectly via urbanisation‐induced increased habitat isolation, smaller habitat area, higher light pollution and increased mowing intensity, we sampled moths with light trapping in 20 grasslands in the urban core of the city of Darmstadt (southwestern Germany) and 20 grasslands in the surrounding area.Moth abundance and diversity decreased with increasing urbanisation. Smaller habitat area and high mowing intensity reduced moth abundance, while other environmental variables including isolation and light pollution had only indirect effects. High levels of urbanisation were associated with reduced moth abundance, which in turn drove declines in diversity. Urbanised sites favoured generalist species and differed in species composition compared to sites in the surrounding.The results show that urbanisation is directly reducing moth abundance and diversity in cities. The negative effect of urbanisation is further attenuated by habitat fragmentation and high mowing intensity, which are both known drivers of biodiversity decline in urban areas and beyond.While urbanisation itself is often irreversible, reducing mowing intensity and preserving larger grassland areas could facilitate moths and other taxa in and around cities. [ABSTRACT FROM AUTHOR]

Reports of major losses in insect biodiversity have stimulated an increasing interest in temporal population changes. Existing datasets are often limited to a small number of study sites, few points in time, a narrow range of land‐use intensities and only some taxonomic groups, or they lack standardised sampling. While new monitoring programs have been initiated, they still cover rather short time periods.Daskalova et al. 2021 (Insect Conservation and Diversity, 14, 1‐18) argue that temporal trends of insect populations derived from short time series are biased towards extreme trends, while their own analysis of an assembly of shorter‐ and longer‐term time series does not support an overall insect decline. With respect to the results of Seibold et al. 2019 (Nature, 574, 671–674) based on a 10‐year multi‐site time series, they claim that the analysis suffers from not accounting for temporal pseudoreplication.Here, we explain why the criticism of missing statistical rigour in the analysis of Seibold et al. (2019) is not warranted. Models that include 'year' as random effect, as suggested by Daskalova et al. (2021), fail to detect non‐linear trends and assume that consecutive years are independent samples which is questionable for insect time‐series data.We agree with Daskalova et al. (2021) that the assembly and analysis of larger datasets is urgently needed, but it will take time until such datasets are available. Thus, short‐term datasets are highly valuable, should be extended and analysed continually to provide a more detailed understanding of insect population changes under the influence of global change, and to trigger immediate conservation actions. [ABSTRACT FROM AUTHOR]

Trait‐based approaches are widespread throughout ecological research as they offer great potential to achieve a general understanding of a wide range of ecological and evolutionary mechanisms. Accordingly, a wealth of trait data is available for many organism groups, but this data is underexploited due to a lack of standardization and heterogeneity in data formats and definitions.We review current initiatives and structures developed for standardizing trait data and discuss the importance of standardization for trait data hosted in distributed open‐access repositories.In order to facilitate the standardization and harmonization of distributed trait datasets by data providers and data users, we propose a standardized vocabulary that can be used for storing and sharing ecological trait data. We discuss potential incentives and challenges for the wide adoption of such a standard by data providers.The use of a standard vocabulary allows for trait datasets from heterogeneous sources to be aggregated more easily into compilations and facilitates the creation of interfaces between software tools for trait‐data handling and analysis. By aiding decentralized trait‐data standardization, our vocabulary may ease data integration and use of trait data for a broader ecological research community and enable global syntheses across a wide range of taxa and ecosystems. [ABSTRACT FROM AUTHOR]

While forest management strongly influences biodiversity, it remains unclear how the structural and compositional changes caused by management affect different community dimensions (e.g. richness, specialisation, abundance or completeness) and how this differs between taxa. We assessed the effects of nine forest features (representing stand structure, heterogeneity and tree composition) on thirteen above‐ and belowground trophic groups of plants, animals, fungi and bacteria in 150 temperate forest plots differing in their management type. Canopy cover decreased light resources, which increased community specialisation but reduced overall diversity and abundance. Features increasing resource types and diversifying microhabitats (admixing of oaks and conifers) were important and mostly affected richness. Belowground groups responded differently to those aboveground and had weaker responses to most forest features. Our results show that we need to consider forest features rather than broad management types and highlight the importance of considering several groups and community dimensions to better inform conservation. [ABSTRACT FROM AUTHOR]

Land use and corresponding habitat loss are major drivers of local species extinctions. Orthoptera as important grassland herbivores showed different responses to land-use intensity in different studies, and the susceptibility of this group remains unclear. We sampled annually for seven years 150 temperate grassland sites across three regions in Germany, for which land-use gradients were quantified as mowing, grazing, and fertilization intensity. We analyzed the effects of land-use intensity on orthopteran diversity and community abundance. To describe species-specific responses to environmental gradients, we employed a new approach termed "niche model," coupled with a randomization procedure, which is sensitive even for rare species for which trends may otherwise be difficult to detect. Based on abundance-weighted means for each species, we quantified the species' occurrence along land-use gradients and identified potential losers and winners of intensive land use. Overall, high land-use intensity negatively affected orthopteran diversity across years and regions, corresponding to decreases with high fertilization, mowing, and grazing intensity. Intensive mowing and grazing negatively affected abundance. Diversity and abundance increased with the time after the last cut. The niche model detected 15 of 29 Orthoptera species as losers of land use, showing significantly higher abundance in grasslands with low-intensity land use. Two species were winners of high land-use intensity, whereas the remaining 12 were assigned as opportunists. Most species were losers of high fertilization intensity, followed by frequent mowing. Grazing intensity was least detrimental at the species level. Omnivorous, herbivorous, and graminivorous species did not differ in their response to land-use intensity, whereas bryovorous/lichenivorous Tetrix species showed consistently negative responses to intensive land use. Our highly replicated, long-term and large-scale survey suggests that further land-use intensification threatens many Orthoptera and causes a consistent diversity loss. Low intensity of fertilization, infrequent mowing, and variable grazing will help to maintain a high diversity of orthopterans. The generality of our niche model approach advances studies on species' susceptibility in various study systems. [ABSTRACT FROM AUTHOR]

Intensification of land use reduces biodiversity but may also shift the trait composition of communities. Understanding how land use affects single traits and community trait composition, helps to understand why some species are more affected by land use than others. Trait-based analyses are common for plants, but rare for arthropods. We collected literature-based traits for nearly 1000 insect and spider species to test how land-use intensity (including mowing, fertilization, and grazing) across 124 grasslands in three regions of Germany affects community-weighted mean traits across taxa and in single taxa. We additionally measured morphometric traits for more than 150 Heteroptera species and tested whether the weighted mean morphometric traits change with increasing land-use intensity. Community average body size decreased and community average dispersal ability increased from low to high land-use intensity. Furthermore, the relative abundance of herbivores and of specialists among herbivores decreased and the relative abundance of species using the herb layer increased with increasing land-use intensity. Community-weighted means of the morphometric traits in Heteroptera also changed from low to high land-use intensity toward longer and thinner shapes as well as longer appendices (legs, wings, and antenna). While changes in traits with increasing mowing and fertilization intensity were consistent with the combined land-use intensity, community average traits did often not change or with opposite direction under increasing grazing intensity. We conclude that high land-use intensity acts as an environmental filter selecting for on average smaller, more mobile, and less specialized species across taxa. Although trait collection across multiple arthropod taxa is laborious and needs clear trait definitions, it is essential for understanding the functional consequences of biodiversity loss due to land-use intensification. [ABSTRACT FROM AUTHOR]

As a rule, communities consist of few abundant and many rare species, which is reflected in the characteristic shape of species abundance distributions (SADs). The processes that shape these SADs have been a longstanding problem for ecological research. Although many studies found strong negative effects of increasing land-use intensity on diversity, few reports consider land-use effects on SADs., Arthropods (insects and spiders) were sampled on 142 grassland plots in three regions in Germany, which were managed with different modes (mowing, fertilization and/or grazing) and intensities of land use. We analysed the effect of land use on three parameters characterizing the shape of SADs: abundance decay rate (the steepness of the rank abundance curve, represented by the niche-preemption model parameter), dominance (Berger-Parker dominance) and rarity (Fisher's alpha). Furthermore, we tested the core-satellite hypothesis by comparing the species' rank within the SAD to their distribution over the land-use gradient., When data on Araneae, Cicadina, Coleoptera, Heteroptera and Orthoptera were combined, abundance decay rate increased with combined land-use intensity (including all modes). Among the single land-use modes, increasing fertilization and grazing intensity increased the decay rate of all taxa, while increasing mowing frequency significantly affected the decay rate only in interaction with fertilization. Results of single taxa differed in their details, but all significant interaction effects included fertilization intensity. Dominance generally increased with increasing fertilization and rarity decreased with increasing grazing or mowing intensity, despite small differences among taxa and regions. The majority of species found on <10% of the plots per region were generally rare (<10 individuals), which is in accordance with the core-satellite hypothesis. We found significant differences in the rarity and dominance of species between plots of low and high intensity for all three land-use modes and for the combined land-use intensity., We conclude that effects of land-use intensity on SADs lead to a stronger dominance of the most abundant species. Furthermore, species which have restricted distributions are more likely to also be rare species in the local SAD and therefore are at high risk of being lost under intensive land use. [ABSTRACT FROM AUTHOR]

Type and intensity of land‐use vary in space and time and strongly contribute to changes in richness and composition of species communities. In this study, we examined land snail communities in forests and grasslands in three regions of Germany. We aimed to quantify the extent to which snail density, diversity, and community composition in forests and grasslands are determined by (1) land‐use intensity, (2) abiotic drivers and (3) biotic substrates, and (4) whether these effects are consistent across regions. In total, we collected 15,607 snail individuals belonging to 71 species and analyzed both direct and indirect effects using structural equation modeling. Snail densities and their local diversity varied across regions and between forest and grassland habitats within a region albeit with contrasting trends. Community composition also differed among regions—more strongly in forests than in grasslands—and each habitat had unique species (18 in forests, 21 in grasslands). In general, the direct impact of land‐use on snail density, diversity, and community structure was on average nine (forests) and seven (grasslands) times lower than the impact of abiotic drivers and biotic substrates which both affected snail assemblages about equally. However, land‐use factors had indirect effects on snail responses through abiotic variables such as soil moisture and soil pH. Furthermore, land‐use factors also had indirect effects via changing biotic substrates, such as plant cover in grasslands and deadwood cover in forests. Our results show that land snails strongly respond to environmental gradients and add an important indicator taxon to the current evidence of land‐use impacts, highlighting the complexity of direct and indirect effects via biotic and abiotic drivers across regions in Central Europe. [ABSTRACT FROM AUTHOR]

Intensification of land use reduces biodiversity but may also shift the trait composition of communities. Understanding how land use affects single traits and community trait composition, helps to understand why some species are more affected by land use than others. Trait‐based analyses are common for plants, but rare for arthropods. We collected literature‐based traits for nearly 1000 insect and spider species to test how land‐use intensity (including mowing, fertilization and grazing) across 124 grasslands in three regions of Germany affects community weighted mean traits across taxa and in single taxa. We additionally measured morphometric traits for more than 150 Heteroptera species and tested whether the weighted mean morphometric traits change with increasing land‐use intensity. Community average body size decreased and community average dispersal ability increased from low to high land‐use intensity. Furthermore, the relative abundance of herbivores and of specialists among herbivores decreased and the relative abundance of species using the herb‐layer increased with increasing land‐use intensity. Community weighted means of the morphometric traits in Heteroptera also changed from low to high land‐use intensity towards longer and thinner shapes as well as longer appendices (legs, wings, and antenna). While changes in traits with increasing mowing and fertilization intensity were consistent with the combined land‐use intensity, community average traits did often not change or with opposite direction under increasing grazing intensity. We conclude that high land‐use intensity acts as an environmental filter selecting for on average smaller, more mobile and less specialized species across taxa. Although trait collection across multiple arthropod taxa is laborious and needs clear trait definitions, it is essential for understanding the functional consequences of biodiversity loss due to land‐use intensification.This article is protected by copyright. All rights reserved. [ABSTRACT FROM AUTHOR]

Trait-based approaches have increased significantly in community ecology during the last decade. This is not least because studies on biodiversity–ecosystem functioning relationships became a major topic in ecology. Species’ functions in ecosystems are mediated by their traits. For a better understanding of the relationships between environmental drivers, the community composition of organisms and ecosystems functioning, it is crucial to understand how these relationships are mediated by the communities’ trait composition. While there are world-wide efforts to set up trait databases, most have so far focused on plants and species-poorer taxa such as birds or amphibians. In contrast, for insects, the large number of species makes the gathering of comparable trait data a challenging task. In addition, there is the danger that generic trait information, which is available from common textbooks, may not be sufficient to detect the response of insect communities to environmental change or the consequences of trait changes for ecosystem functioning. One method to overcome this is to take morphometric measurements of species. In this study we measured morphometric traits of a total of 179 Heteroptera species that were sampled by sweep-netting on a total of 150 managed grassland plots across three regions in Germany between 2008 and 2012. These plots represent the whole range of grassland management intensities from extensively used pastures to mown pastures to intensively managed and fertilized meadows. In this paper we provide a database of mean values of 23 morphometric measures across sex and morphotypes for each sampled Heteroptera species. Morphological traits are assumed to be related to their adaptation and function in the environment. Thus the relative morphometric traits can be used as proxies for ecological features of a species that may affect its performance or fitness. Our database can be used by future trait-based studies for developing and testing hypotheses of the functional significance of these traits. Examples include studying the functional responses of insect communities to environmental drivers or studying how the change in trait composition affects ecosystem processes. [ABSTRACT FROM AUTHOR]