Journal of Applied Ecology

While many herbicide active substances have been banned and weed infestation is a major threat to crop productivity, it is still unknown to what extent natural weed control provided by seed predators can help farmers manage weed communities. We aim to quantify the contribution of seed predators to crop productivity through weed control and to evaluate whether the magnitude of their influence depends on farming systems such as conservation agriculture. We set up 112 seed predator-exclusion cages in 28 cereal fields in France (14 pairs of conservation and conventional agriculture fields), surveyed weed emergence and biomass, measured crop yield and sampled the main seed predators: carabid beetles and rodents. We found that seed predators activity reduces the yield loss due to weeds by 20%. By extrapolation, it represents an economic gain of 285{euro}/ha. However, the yield loss remains at 60% below the maximum crop yield potential reached in the absence of weeds. Moreover, conservation agriculture enhances weed control, but this does not translate into increased crop yield. This study demonstrates the tangible importance of considering seed predators for weed control but highlights the need to combine this approach with weed control practices or to substantially redesign cropping systems to enhance the beneficial effects of biodiversity on crop productivity. Significance statementAlthough weed biomass is the main driver of decreasing the crop productivity worldwide and the use of herbicides is massively disparaged, we have not yet quantified the role played by on-farm biodiversity to control weeds. Using an experimental design set up in 28 commercial cereal fields in France, we showed that weed seed predators reduce crop yield loss due to weeds by 20%. By extrapolation, it represents an economic gain of 285{euro}/ha. However, in the absence of any other weed control practices, the yield loss remains at 60% below the maximum crop yield potential reached in the absence of weeds. This study demonstrates the quantitative importance of considering seed predators to design pesticide-free systems.

O_LIIn the absence of chemical control with its negative side effects, fungal pathogens can cause large yield losses, requiring us to develop agroecosystems that are inherently disease resistant. Grassland biodiversity experiments often find plant species diversity to reduce pathogen pressure, but whether incorporating high biodiversity levels in agricultural fields have similar effects remains largely unknown. C_LIO_LIWe tested if undersown plant species diversity could reduce barley disease, and whether the effect was mediated through above- or belowground mechanisms, by combining an agricultural field trial with a soil transplant experiment. C_LIO_LIAs predicted, barley disease decreased in the presence of undersown plants. Undersown species richness had no effect, but their abundance led to early season disease reduction. Aboveground mechanisms underpinned this disease reduction. Barley yield slightly decreased with increasing undersown species richness, and undersown species varied in their impact on yield. C_LIO_LIWe identified two undersown species with similar functional traits that contributed most to disease reduction and had the potential to increase barley yield. Furthermore, our results indicate that aboveground mechanisms caused this. We show that agroecosystem functioning can be improved without trade-offs on yield by targeted selection of undersown species. C_LI

Global biodiversity is declining at an unprecedented rate, with agriculture as one of the major drivers. There is mounting evidence that intercropping can increase insect biodiversity while maintaining or increasing yield. Yet, intercropping is often considered impractical for mechanized farming systems. Strip cropping is a type of intercropping that is compatible with standard farm machinery and has been pioneered by Dutch farmers since 2014. Here, we present ground beetle data from four organically managed experimental farms across four years. Ground beetles are sensitive to changes in habitats and disturbances, and hold keystone positions in agroecosystem food webs. We show that strip cropping systems can enhance ground beetle biodiversity, while other studies showed that these increases have been achieved without incurring major yield loss. Strip cropped fields had on average 15% more ground beetle species and 30% more individuals than monocultural fields. The higher ground beetle richness in strip crops was explained by the merger of crop-related ground beetle communities, rather than by ground beetle species unique to strip cropping systems. The increase in field-level beetle species richness in organic agriculture through strip cropping approached increases found for other readily deployed biodiversity conservation methods, like shifting from conventional to organic agriculture (+19% - +23%). This indicates that strip cropping is a potentially useful tool supporting ground beetle biodiversity in agricultural fields without compromising food production.

By concentrating rodents along verges, roads can reshape rodent-mediated seed dispersal, yet empirical tests remain scarce. We conducted a two-year field experiment in Mediterranean oak woodlands in southern Portugal to test how seed dispersal varies with distance from roads across road type (paved vs. unpaved) and road-forest context (edge vs. non-edge). We tracked labeled holm oak acorns, recording dispersal distances and the number of dispersal events. The two metrics responded differently to road distance. Dispersal distances changed little with distance from roads in non-edge contexts but increased in edge road-forest contexts (2x longer at 400 m than at 10 m) and showed a year x distance-to-road interaction, with longer dispersal distances farther from roads in the second year (a poor mast year). Dispersal distances were also longer when acorns were deposited under shrubs and in areas of higher tree density, and decreased with greater natural acorn availability. In contrast, the number of dispersal events declined with distance from roads (30% more events at 10 m than at 400 m) and was higher along unpaved than paved roads (39% more events). Dispersal frequency also increased in the poor mast year and with shrub cover. No acorns crossed the road. Thus, road verges can concentrate rodent seed handling but do not increase dispersal distances near roads nor provide cross-road seed connectivity; instead, dispersal outcomes depend on edge context, road type, and microhabitat structure. Management that retains structural cover at verges and the adjacent forest edge (e.g., shrub patches and non-uniform clearing) can harness verge-associated activity to increase acorn deposition in sheltered microsites and promote regeneration farther into forest interiors in roaded landscapes.

Understanding the risks of pesticide exposure in agricultural environments is crucial for maintaining essential agroecosystem services. Pollinators behaviour can influence exposure routes, but their role in the formation of pesticide-induced ecological traps has received little attention. Using an individual-based modelling framework (BEE-STEWARD), I examined how three behavioural processes - preference for mass-flowering crops, inadvertent social information (ISI) use, and pesticide-induced foraging bias - affect nectar and pollen visitation rates of buff-tailed bumblebees (Bombus terrestris) to pesticide-treated crop patches located near or far from the colony. All behavioural processes increased visitation to treated patches, though their magnitude and context differed. Crop preference consistently elevated visitation rates, ISI use amplified nectar foraging on nearby crops when combined with preference, and pesticide-induced bias in foraging behaviour strongly increased pollen visits across distances. These results suggest that pesticides capable of altering patch quality assessment can create ecological traps for pollinators, even when untreated patches are available. Incorporating behavioural pathways into pesticide risk assessments could improve mitigation strategies in pesticide-treated agricultural landscapes.

Pollinator conservation schemes are typically focused on conserving existing-, restoring degraded- or establishing new wild bee habitats. The effectiveness of such conservation schemes depends on the presence of dispersal corridors that allow habitat colonization by bees. Nonetheless, we lack an understanding of the role of semi-natural habitats edges on the connectivity of pollinator communities across intensively managed landscapes. Here, we use data from wild bee communities comprising 953 occurrences from 79 species of non-parasitic bees, sampled at 68 locations distributed across a Norwegian and a Danish landscape to show that the proportion of semi-natural habitat edges is positively correlated to bee species richness and habitat connectivity. Specifically, we found that wild bee species richness sampled along roadsides increased with the proportion of semi-natural habitat edges within1.5 km of the study sites and with local plant species richness. We combined maps showing the proportion of seminatural habitat edges with least cost path analysis to find the most likely dispersal route between our bee communities. We find that these least cost path lengths provide better models of bee species compositional similarity than geographic distance (|{Delta}AICc| > 2), suggesting that seminatural habitat edges act as dispersal corridors in intensively managed landscapes. However, we also find that compositional similarity between communities depend on site-specific plant species richness stressing the importance of improving the habitat quality of edge habitats if they are to function as dispersal corridors. We discuss potential management options for improving wild bee habitat conditions along seminatural habitat edges and illustrate how maps of least cost paths can be used to identify dispersal corridors between pollinator habitats of conservation priority. Maps of dispersal corridors can be used to direct wild bee habitat management actions along seminatural habitat edges to facilitate the dispersal of bees between larger grassland habitats.

Wood-pastures--mosaic landscapes composed of scattered trees, shrubland, and grassland--are a cornerstone of Europes ecological and cultural heritage. Yet their conservation is increasingly threatened by the decline of disturbance regimes maintained by both megaherbivores and traditional agro-silvo-pastoral practices, leading to afforestation, biodiversity loss, and heightened wildfire risk. To evaluate the conservation potential of restoring megaherbivore communities to rebalance disturbance regimes in Italian wood-pastures, we reconstructed a Holocene, pre-agricultural baseline assemblage and compared its ecological functions with those of the current, impoverished megaherbivore community. Using zooarchaeological records, functional trait data, and allometric estimates of movement capacity and plant biomass removal, we demonstrate that a reconstructed assemblage would substantially increase functional diversity--by +0.19 in Functional Divergence and +0.22 in Functional Dispersion (on a scale from 0 to 1)-- and result in much higher vegetation consumption (11.88 versus 4.45 t km-2 yr-1), with a shift toward greater grazing. This would support the maintenance of open, heterogeneous habitats, reduce fine-fuel loads, and likely promote long-term soil carbon sequestration, aligning with EU climate and restoration objectives. Enhanced megaherbivore movement capacity would also increase endozoochorous seed dispersal, improving vegetation connectivity and adaptive potential under climate change. Additionally, we synthesized socioeconomic insights through a SWOT analysis of megafauna rewilding in Italy. Key strengths include strong cultural associations with megafauna, active rewilding organizations, and emerging economic opportunities tied to ecotourism and rural branding. However, challenges related to conflict, zoonoses, early-stage management requirements, and limited communication among stakeholders remain substantial. Our findings underscore the ecological and cultural relevance of megaherbivore rewilding for restoring wood-pastures in Italy--a context where rewilding remains underrepresented in public and academic discourse. By providing a quantitative, integrative assessment, this study offers foundational evidence to inform national ecological restoration strategies and promote ambitious, process-based approaches to conserving Europes semi-natural cultural landscapes.

Roadkill hotspots concentrate animal movement and mortality, but whether they also concentrate animal-mediated seed flow--a key pathway of plant connectivity--remains unknown. In Mediterranean oak woodlands of southern Portugal, we used seed mimics to test how road type (paved vs. unpaved) and road-forest context (edge vs. non-edge) shape carnivore-mediated seed crossings, and whether crossings coincide with roadkill hotspots detected by kernel density analysis. Bayesian logistic models indicated that seed-crossing probability was about twice as high on unpaved as on paved roads (predicted means 0.28 vs. 0.14), with weaker evidence for a negative edge effect. Crossing probability also tended to increase with carnivore abundance and distance to streams, and decrease with rodent density, albeit with some uncertainty. Crucially, paved sections intersecting roadkill hotspots showed nearly threefold higher predicted crossing probabilities than non-hotspot sections (0.51 vs. 0.18). These findings support hotspot-guided mitigation on paved, non-edge segments--for example targeted speed management, fencing that funnels animals to existing culverts/underpasses, and verge management to reduce prey/scavenging attractants--thereby improving road safety while maintaining functional seed-mediated connectivity. HighlightsO_LIUnpaved roads roughly double seed-crossing probability C_LIO_LIRoadkill hotspots roughly triple seed-crossing probability C_LIO_LIHotspot-guided mitigation cuts risk, keeps carnivore-driven connectivity C_LI

Studies on the effects of grazing disturbances in grasslands have shown mixed results for spider diversity, mainly regarding their guilds. While ungrazing, low, and moderate grazing potentially enhance diversity of orb-weavers, heavy grazing seems to reduce specie[s] richness. On the population level, studies of orb-weavers are scarce, and the effects of grazing are unknow. In this way, we investigated the effects of different levels of grazing on population persistence of orb-weaver spiders, hypothesizing that low to intermediate disturbances benefit populations. We predict that high grazing, due to the removal of vegetation structure, will negatively affect occupancy and abundance of orb-weavers. For that, we experimentally controlled grazing pressure and obtained population occurrence and counts of two orb-weaver spider species, Argiope argentata and Alpaida quadrilorata. We found that A. argentata was directly affected by grazing, as it relies on higher vegetation for web-building. In contrast, A. quadrilorata, which occurs in cattle-resistant rosette plants, showed no effects of grazing. Implications for insect conservation: Our study emphasizes the need for balanced grazing practices and habitat conservation to protect orb-weaver spiders and other arthropods, as well as, species-specific effects for species from the same guild, underscoring their ecological significance in maintaining ecosystem stability.

IntroductionHuman land-use intensification and the resulting habitat loss are primary drivers of insect pollinator declines. Habitat restoration offers a promising approach to counteract these declines, yet landscape-level evaluations of bee responses to restoration and management remain limited. We conducted a two-year, landscape-scale study in Wisconsin, USA, to assess how different intensities of tallgrass prairie restoration and management affect bumble bees (Bombus spp.). ObjectivesThis study aimed to determine whether (1) bumble bee abundance and diversity increase with assisted restoration, and (2) outcomes differ between low-(seeded only) and moderate-intensity (seeded and managed with prescribed fire) interventions. MethodsUsing catch-and-release surveys, we measured bumble bee abundance and diversity at 32 sites representing a gradient in restoration intervention: no intervention (unassisted recovery), low intervention, and moderate intervention. ResultsBumble bee abundance and diversity were higher at assisted restoration sites (low and moderate intervention) than at unassisted sites. Although both tended to be greater at moderate than low intervention intensities, these differences were not statistically significant. Bumble bee community composition also differed across intervention intensity, driven by shifts in dominant species (e.g., B. impatiens and B. griseocollis). Rarer taxa, including endangered and vulnerable species, occurred only at assisted restoration sites, with the largest populations at moderate intervention sites. Across all sites, bumble bee responses were strongly and positively associated with floral abundance, but not with semi-natural habitat in the surrounding landscape. ConclusionOur findings demonstrate that assisted grassland restoration can effectively increase bumble bee abundance and diversity, supporting its value as a conservation practice for pollinators. Implications for Practice: (1) Grassland restorations targeting plant communities can successfully support nontarget pollinators across a range of management intensities and landscape contexts. Adding seeds of pollinator-preferred plants could improve restorations with low floral abundance and diversity. (2) Management of existing restorations is important to maintain abundant floral resources and diverse pollinator communities. Because sites varied widely in prescribed fire use, our findings likely represent a conservative estimate of its benefits, and higher intervention intensity (e.g., repeated seeding, regular fire, mechanical or chemical shrub and invasive plants control) may further enhance outcomes for bumble bees.

Arthropods comprise the majority of terrestrial biodiversity and play key roles in ecosystem functioning. Biodiverse grasslands support many arthropods, yet such ecosystems have declined due to land conversion and management changes. While restoration aims to conserve species-rich grasslands, long-term effects of plant richness on arthropod communities and associated functions remain underexplored. We addressed this gap by quantifying arthropods, herbivory, and predation over 13 years (2010-2022) across 80 grassland plots with varying plant richness. We examined (1) temporal trends in arthropod communities, herbivory and predation and whether changes depended on plant richness, (2) whether plant richness effects varied or strengthened over time, and (3) whether arthropod changes affected associated functions. Arthropod metrics declined over time across all plant richness levels, with average losses mainly being more pronounced in species-poor mixtures. Plant richness consistently had a positive effect on arthropods and their functions, although this effect varied between years without a consistent temporal trend. Notably, temporal changes in arthropod community metrics did not predict shifts in associated functions. Our findings highlight the dynamic interplay between plant richness and arthropods. From a conservation perspective, we can conclude that diversification in grasslands- the increase in plant diversity- directly supports arthropods and associated functions. Additionally, first trends indicate that the maintenance and protection of diverse semi-natural grasslands over a long period might mitigate the arthropod loss driven by environmental changes. In other words, diverse grasslands may buffer against the ongoing arthropod loss, though this effect may take years to become apparent. This again emphasizes the long-term nature of conservation efforts.

Many flying insects, such as bees, wasps, and hoverflies, live aboveground, but depend on soil for nesting, development, and overwintering. In agricultural landscapes, soil is managed for production and therefore frequently subjected to disturbances such as ploughing. The impacts of ploughing on flying insects that spend part of their life cycle belowground remain largely unknown. To investigate the effects of ploughing on ground-nesting flying insects, we conducted a two-year field experiment in flower strips subjected to different treatments, ranging from annual ploughing to four years without ploughing. Insects emerging from the soil were sampled using emergence traps, allowing a direct assessment of their response to ploughing at different frequencies. For each treatment, we measured insect biomass, abundance, and body size. We found that ploughing substantially reduced flying insect biomass. When sites were left unploughed, biomass increased rapidly, particularly during the first years of recovery. However, regardless of the time since the last disturbance, ploughing always reduced insect biomass to similarly low levels, driven primarily by declines in the abundance of large insects. Our findings highlight that even moderate reductions in ploughing frequency, for example, only every second year, can benefit ground-nesting flying insects and point to the potential for incorporating reduced ploughing frequencies into agricultural management and agri-environmental schemes.

Animal population control is widely used to mitigate conflicts between wildlife and agriculture worldwide. Structured, monitored removals are rare in South America, however, and their consequences for wildlife populations as well as their effectiveness in reducing crop damage are little understood. Using eight years of data from an experimental white-lipped peccary management program in an agricultural mosaic in the Brazilian Cerrado biome, we assess how structured, non-lethal removals affect both peccary demography and second-crop corn damage. Leslie removal models based on 6,619 captured individuals indicated that cumulative removals to approximately 85% of the initial population strongly reduced peccary abundance, with limited demographic compensation despite fluctuations in reproductive output. Corn crop damage, quantified with satellite imagery, declined over time and was correlated with peccary population size. Interannual variation in population growth and juvenile recruitment was poorly explained by climate, fire, or landscape composition. Source-sink dynamics likely play a role in maintaining healthy populations at the regional scale. Together, these results demonstrate that sustained and monitored ungulate removals can reliably reduce population size and agricultural damage, supporting coexistence between wildlife and food crop production in human-dominated tropical landscapes.

The positive effects of large herbivores on plant diversity in grasslands have so far been mainly attributed to increased light availability or suppressed dominance, and thus to the consequences of aboveground biomass consumption (trophic effects). However, these insights are mainly derived from short-term experiments. Using a 46-year experiment in a salt marsh, comparing cattle grazing, mowing (as a proxy of aboveground consumption) and the ungrazed control, we found that the non-trophic effects (e.g. trampling, deposition of urine and dung) of large herbivores on plant diversity increased over time, exceeding that of the trophic effects after 23 years. This long-term accumulation of non-trophic effects through slow ecosystem-level feedback highlights the sustainability of using low to moderate densities of large herbivores to conserve plant diversity. Our results emphasize the need for the conservation and re-introduction of large herbivores, domestic or wild, to sustain long-term grassland plant diversity.

O_LIOrganic farming is seen as a prototype of ecological intensification able to conciliate crop productivity and biodiversity conservation in agricultural landscapes. However, how natural enemies, an important functional group supporting pest control services, respond to organic farming at different scales and in different landscape contexts remain unclear.\nC_LIO_LIUsing a hierarchical design within a vineyard-dominated region located in southwestern France, we examine the independent effects of organic farming and semi-natural habitats at the local and landscape scales on natural enemies.\nC_LIO_LIWe show that the proportion of organic farming is a stronger driver of species abundance than the proportion of semi-natural habitats and is an important facet of landscape heterogeneity shaping natural enemy assemblages. Although our study highlight a strong taxonomic group-dependency about the effect of organic farming, organic farming benefits to dominant species while rare species occur at the same frequency in the two farming systems.\nC_LIO_LIIndependently of farming systems, enhancing field age, reducing crop productivity, soil tillage intensity and pesticide use are key management options to increase natural enemy biodiversity.\nC_LIO_LISynthesis and Applications. Our study indicates that policies promoting the expansion of organic farming will benefit more to ecological intensification strategies seeking to enhance ecosystem services than to biodiversity conservation.\nC_LI

Assessing the impact of herbicide drift on plant-pollinator interactions is crucial for providing insight into the causes of ongoing pollinator declines. The recent exponential increase in the use of the synthetic auxin herbicide dicamba, which is known to drift long distances following application, renders this concern especially acute. However, experimental data on the consequences of dicamba drift on plant-pollinator interactions are lacking from weed communities in natural settings. We assessed the indirect effects of dicamba drift on pollinator visits for 11 weeds of agricultural crops using a common garden field experiment, focusing on the potential for changes in pollinator abundance and alterations to both plant traits and patterns of pollinator visitation. We found variation among plant species in the extent of damage from dicamba drift exposure, and variation in how growth, flowering time, and flower displays were impacted, with some species showing negative impacts and others showing little effect. Pollinator frequencies were reduced in dicamba-exposed plots, and pollinator approaches and foraging visits were reduced for some weed species yet not others. Structural equation modeling revealed that the relationship between flower display and pollinator visits was disrupted in the presence of dicamba compared to control plots. Our study provides the most comprehensive picture to date of the impacts of dicamba drift on plant-pollinator interactions, with findings that highlight an underappreciated role of services supplied by weedy communities at the agroecological interface.

O_LICavity-nesting bees and wasps provide essential ecosystem services such as pollination and pest control. Within urban environments, it is likely that cavity-nesting insects are using greenspaces to forage for food and nesting resources, and thus may benefit from urban greenspace management interventions, such as the addition of flower patches and "bee hotels" (trap nests). C_LIO_LIIn contrast to the relatively large body of work demonstrating the effects of wildflower provisioning on bees in an agricultural context, there have been few studies testing the benefits of floral provisioning, or the relative importance of nest site and food constraints on urban cavity-nesting bees and wasps. Consequently, we lack an empirical evidence base for optimising and informing conservation interventions for these taxa. C_LIO_LITo understand how the addition of floral resources influences cavity-nesting insect communities, we conducted a 2-year study in urban greenspaces used for horticulture (allotments). We manipulated floral and nesting resources by adding nectar-rich flower patches and artificial trap nests, and compared nest colonisation by cavity-nesting bees and wasps in sites with floral additions and where no additions were made. Our sites were configured along an urbanisation gradient, allowing us to examine how surrounding urbanisation influenced these patterns. C_LIO_LIContrary to our predictions, we found no significant difference in trap nest uptake in sites where floral resources were added, compared to control sites. However, cavity-nesting insect abundance showed a 6-fold decrease over our urbanisation gradient. The addition of floral resources did not mitigate the negative effects of urbanisation on cavity-nesting insects. C_LI Synthesis and Applications: Although enhancing floral resources in urban systems is a recognised strategy for conserving key pollinators such as social bees, our findings suggest that this approach alone does not address the challenges faced by cavity-nesting bees or wasps in urban landscapes. Our results suggest that accounting for the diversity of resource requirements and incorporating landscape-scale analysis is essential to ensure local conservation interventions will benefit a diversity of insect communities.

O_LIFarmland eco schemes implemented under the current Common Agricultural Policy (CAP) of the European Union are often considered ineffective in halting farmland bird declines. Fallow fields, often seeded with dedicated seed mixtures, rate among the more beneficial eco scheme types. Yet, the CAP currently defines no minimum criteria for fallow fields to qualify as eco scheme, likely jeopardizing their potential biodiversity benefits. C_LIO_LIWe investigated the attractiveness of four fallow field types established under CAP eco schemes and dedicated bird conservation programs in Southern Germany. Our 2-year surveys on > 100 fields focused on the non-breeding season, where food limitation can become particularly problematic. We modelled bird incidences also in response to vegetation structure and adjacent landscape features to derive minimum criteria for effective fallow field eco schemes. C_LIO_LIFallow field types varied only mildly in overall species richness but showed striking differences in the attracted species. Finches in particular tended to preferentially visit 1-year fallow fields, while buntings tended towards 2-year and older field types. 1-year CAP fallows, however, are typically removed before mid-winter, and thus potentially act as a trap to farmland birds and other wildlife. C_LIO_LIThe investigated species consistently preferred larger fallow fields with a more differentiated vegetation structure. Placement close to woods and hedgerows positively affected birds inhabiting woodland ecotones, while classic farmland species showed higher incidences on fallow fields embedded in open landscapes. C_LIO_LI Policy implications Our findings call for the ongoing CAP revisions to specify minimum requirements that qualify fallow fields as eco schemes. These should include an at least biennial cycle, a diversification of seed mixtures, standards for fallow field size, and criteria for their placement in the landscape matrix. C_LI

Grasslands are diverse ecosystems that are increasingly threatened by intensive land use. Restoring grasslands by reducing land-use intensity may support insect abundance and diversity, helping to halt insect declines. To test for the effect of reduced land use on invertebrates, we studied an experiment (established 2020) at 45 sites across three regions of Germany. We hypothesized that reduced land use increases invertebrate abundance and diversity, with larger effects in less intensively used grasslands. Using suction sampling, invertebrates were quantitatively sampled in May 2021 and May 2023, with 2021 samples identified by DNA meta-barcoding. Reducing land use to a single late mowing increased invertebrate abundance by 41% after one year and 99% after three years. However, species richness, Shannon diversity, and Simpson diversity did not differ between treatments and controls. Finding more individuals in grasslands with reduced land use suggests that species already present benefit, rather than additional species being recruited from the surrounding area. The effect of land-use reduction on abundance was consistently influenced by land use in the surrounding matrix, with larger positive effect sizes at grasslands with lower mowing frequency but higher fertilization. In spite of these local differences in the magnitude of restoration effects, the consistent increase in invertebrate abundance suggests that reducing land-use intensity can enhance invertebrate populations with potential benefits for ecosystem functions. It will be important to study how outcomes of land-use reduction develop over time, as land-use reduction is likely more successful when implemented permanently.

The effects of habitat fragmentation on insects are well documented, yet most studies overlook extinction debt. We investigated carabid beetles in 25 remnant urban forests in Helsinki, Finland, spanning unfragmented, recently fragmented, and historically fragmented sites. Across 3162 individuals and 34 species, we analysed species richness, community composition, and traits including dispersal capacity, habitat specialisation, and body size both at the community and population levels. We found no extinction debt: species richness remained stable, but community composition shifted rapidly. Forest specialists declined non-linearly within three decades post-fragmentation before partially recovering, whereas open-habitat species showed the opposite pattern. Dispersal-limited species lost richness without compositional change, while highly-dispersive species maintained richness but altered community composition. Individual size, mass, and dispersal traits showed no consistent patterns. Our study demonstrates rapid, trait-mediated responses to fragmentation in short-lived beetles and highlights the importance of considering specialisation and dispersal in urban conservation planning.