Abstract Birds and bats are relevant natural enemies of pests in fruit crops. However, by preying also on arthropod natural enemies, they may act as intraguild predators that can lead to pest release. Disentangling how these two groups intervene in different ecological relationships is thus essential to understand their relative contribution and complementarity in pest control provision. We used dietary DNA metabarcoding to build tri‐trophic networks that account for direct and indirect interactions among top predators (birds and bats), mesopredators (spiders) and pests (insects) in apple and blueberry crops. To identify species closely linked to pests, we estimated modularity. To evaluate their topological and tri‐trophic role, we quantified their centrality and the extent of distinct predatory pathways in their diets (i.e. direct pest predation, intraguild predation or both). Finally, in the case of birds in apple crop, we tested if the topological and tri‐trophic role of species depended on their abundance, degree of insectivory and morphological traits. The network was modular in both crops, with birds and bats occupying distinct modules feeding on different prey. Bats tended to be more directly connected to pests than birds, which were more frequently involved in intraguild predation. Among birds in the apple crop, higher abundance increased direct pest predation, whereas greater insectivory favoured intraguild predation. Morphology further shaped topological position, with smaller species with less pointed wings demonstrating higher centrality values. Birds and bats showed different and complementary roles in pest control service, a pattern consistent among fruit crops. Both vertebrate groups were associated with different prey, and birds were more prone to promote pest release than bats, although such effect was weaker for common and less insectivorous species. Synthesis and applications . Our study highlights that by combining interaction networks, tri‐trophic cascades and species traits, we can better understand the role of species on the control of pests in fruit crops. In particular, our results point out that promoting bats and abundant birds may be an efficient strategy to enhance pest control in fruit orchards.
Abstract To improve ecosystem restoration, synthesizing information from multiple projects to identify approaches that achieve desired goals is needed. Distributed management experiments can be challenging when individual project objectives vary, and local site conditions can mediate responses; yet coordinated, systematic approaches promise improved understanding and longer term efficiency. Precipitous declines in the global extent of saltmarsh have stimulated rapid increases in restoration activities, but outcomes remain challenging to predict. We tested the responses of bird and vegetation communities to two types of restoration—sediment addition and hydrological modification—across 30 restored marshes along the USA's Atlantic Coast, up to 7 years post‐restoration. To determine if site conditions mediated responses, we also examined the effects of site‐level attributes, such as tidal amplitude and latitude. We found that projects that raised elevation via sediment addition increased the cover of vegetative species of interest, while those that modified hydrology without altering elevation had mixed effects on vegetation. The effects of sediment addition and hydrological modification were more limited for avian species, but results suggest that increases in both abundance and diversity can materialize through modification of the vegetative community. The magnitude of the restoration effect was mediated by site‐level attributes, including tidal amplitude, marsh elevation and latitude. Policy Implications : Our findings demonstrate that saltmarsh restoration can yield measurable ecological benefits within a few years, but outcomes depend strongly on local site conditions. Restoration strategies that increase elevation are more likely to produce consistent vegetation benefits, while outcomes of hydrological modification are more context dependent and variable. Our results highlight the importance of incorporating site‐specific factors into restoration planning and tailoring approaches accordingly. Long‐term monitoring over decadal timescales is essential to evaluate true project outcomes and to guide future adaptive management.
Abstract Biotic resistance to plant invasion is driven by competition with the resident vegetation and antagonistic interactions with other biota in the community, but how these mechanisms operate after invasion control remains poorly understood. We assessed whether the resistance to reinvasion by lodgepole pine ( Pinus contorta ) and to secondary invasion by radiata pine ( Pinus radiata ) and Douglas fir ( Pseudotsuga menziesii ) differs between uninvaded grassland and sites where P. contorta had been controlled. We set up a factorial field experiment in the New Zealand High Country combining animal exclusion and vegetation removal treatments in grassland areas and previously controlled stands of P. contorta . Seeds of all three conifer species were sown in two cohorts, and we monitored seedling emergence, survival and resulting establishment over an 18 month period. Seedling emergence and survival were differently influenced by animal access and resident vegetation, and the effects differed between habitats. Animal access reduced seedling emergence, particularly in controlled pine stands, showing early consumer‐driven biotic resistance. In the grassland, intact vegetation increased seedling emergence, suggesting facilitation under stressful conditions, while no such effect occurred in the controlled pine stands. In contrast, seedling survival was consistently lower in the presence of vegetation across both habitats, showing biotic resistance driven by plant competition. The resulting seedling establishment was lowest in open and undisturbed plots in controlled pine stands, indicating increased biotic resistance as a buffer against reinvasion and secondary invasion. Our results show that the components of biotic resistance following invasion control can shift over time and can be modified by the legacy of the primary invader. Consumers primarily limit establishment during the early seed‐to‐seedling transition and plant competition thereafter, together finally providing resistance against reinvasion and secondary invasion. These findings highlight that post‐control legacies can impact habitat invasibility, with implications for the prioritisation of non‐native conifer management. Synthesis and applications . Post‐control areas are less vulnerable to reinvasion when vegetation structure and consumer communities are maintained. Managers should prioritise preventing establishment in uninvaded grasslands, while using grazing and retaining woody debris to strengthen natural biotic resistance and improve long‐term, cost‐effective invasive conifer control.
Abstract Preventing weed invasion in artificial grasslands is essential for maintaining ecosystem function and sustainable management. Previous studies have shown that species patch size controls inter‐ and intraspecific interactions, leading to the hypothesis that it can influence weed invasion. However, there is no consensus on its actual role in regulating this process. We manipulated four native‐species patch sizes (0.0625, 0.25, 1.0 m 2 and mixed) to create a gradient of inter‐ and intraspecific interactions and tested their effect on resistance to two introduced weeds (annual Consolida ajacis and perennial Paspalum distichum ). Resistance was quantified by measuring native versus invasive biomass in the artificial grasslands in two consecutive years, and key soil nutrient parameters were assessed to explore the underlying mechanisms, including soil organic carbon, ammonium (NH 4 + ), nitrate (NO 3 − ) and available phosphorus. Community biotic resistance was patch‐size dependent: the smallest patches exhibited the highest resistance to invasion. Invasive biomass was negatively related to native biomass across invaded plots, indicating greater biotic resistance in more productive communities. The relationship between native productivity and biotic resistance depended on invader identity, being strong for the annual invader C. ajacis but weak for the perennial invader P. distichum . Smaller patches were associated with higher native productivity, greater invasion resistance and altered soil nutrient dynamics, patterns that are consistent with stronger interspecific interactions, niche complementarity and more efficient resource use for invaders. The contrasting responses of the annual and perennial weeds suggest that spatial structure interacts with invader life‐history traits, with annual invaders appearing more sensitive to fine‐scale competition than perennial invaders, which might be able to tolerate or exploit spatial heterogeneity at least in the short term. Synthesis and applications . This study demonstrates that spatial arrangement of native species is a key driver of invasion resistance through its effects on plant interactions and soil processes. By showing how smaller patches enhance native productivity, increase resistance to invasion and influence soil nutrient dynamics, we identify spatial biodiversity design as a practical, nature‐based solution for maintaining soil health, productivity and short‐term resilience in artificial grasslands. These findings advance ecological understanding by linking spatial community structure with above–below‐ground feedbacks that govern ecosystem stability.
Abstract Riparian forest buffers are a potentially potent nature‐based solution for mitigating environmental degradation and improving biodiversity and ecosystem functioning in stream‐riparian networks. However, uncertainties about how buffer size, spatial configuration and land‐use intensity shape outcomes and trade‐offs hinder management applications. We conducted coordinated field surveys and modelling across four European countries to evaluate how riparian forest properties influence stream‐riparian environments, biodiversity, ecosystem processes and macroinvertebrate functional traits along agricultural and urban land‐use gradients. Riparian forest buffers had strong effects on habitats, increasing shading and coarse woody debris. Sediment deposition was halved in buffered stream reaches, and longer buffers lowered thermal maxima in stream and riparian habitats by 13%–17%. Buffers further reduced effects of increasing agricultural land use on soluble reactive phosphate concentrations, although this response was highly variable. These environmental changes were associated with multiple effects on biodiversity and ecosystem function. Buffer presence and/or increasing length were associated with 30%–167% increases in microbial detritus decomposition, a 44% increase in riparian ground beetle diversity, and 18%–77% increases in stream macroinvertebrate diversity and the EPT biotic index, and macroinvertebrate leaf shredding and algal grazing traits. In contrast, algal biomass accrual and web‐building spider diversity declined by 33% and 36%, respectively, in buffered reaches. As land‐use intensified, riparian forest buffers helped maintain macroinvertebrate functional diversity and shredding, predation, and filtration traits, and saturated fatty acid content in terrestrial predators. In contrast, macroinvertebrate particle‐gathering traits declined. The spatial configuration of riparian forest influenced stream ecosystems at local scales: dissolved phosphorus and diatom species richness declined as spatial proximity among upstream riparian forest blocks decreased, while a diatom‐based biomonitoring index increased. Synthesis and applications . Riparian forest buffers support biodiversity, ecosystem functioning and food webs in human‐modified landscapes, and dampen land‐use and climate stressors (sediments, nutrients, thermal maxima), motivating their wider use in management. These outcomes were regulated by the presence or size of mostly small, mature buffers and sometimes by proximity among riparian forest blocks upstream, indicating that even modest investments in expanding existing buffer networks are likely to deliver cumulative ecological benefits.
Abstract Impacts attributed to global change, such as weather anomalies, land‐use changes and anthropogenic disturbances, often provoke demographic catastrophes mediated by the deterioration of reproductive output, especially in slow‐paced animals, that is top predators, often used as biological indicators of ecosystem networks. In our study, we aimed to disentangle the bioclimatic variables affecting the breeding performance of a declining ground‐nesting raptor in southern Spain, the Montagu's harrier ( Circus pygargus ), a steppe‐specialist species highly affected by climate change and agricultural intensification. We also investigated how conservation measures implemented at nest scale modulated breeding outputs along with environmental variables. Furthermore, we assessed the long‐term viability of the population under different climatic and conservation scenarios. Our analyses suggested that the breeding performance of the population is positively influenced by spring and autumn precipitation, habitat heterogeneity and some conservation measures; on the other hand, it is negatively influenced by human disturbance. Our population viability analysis suggested that nest‐focused conservation measures—for example fences, unharvested buffers—may partially buffer the detrimental effects of weather anomalies. However, local conservation actions may not completely offset population decline in the long term. Policy implications . Our analyses suggest that the species will remain dependent on intensive, multi‐scale conservation actions in the long term, a pattern likely shared by many pseudo‐steppe and farmland birds affected by global change. Beyond nest‐focused conservation actions, integrative broad‐scale policies aiming to mitigate climate change, habitat homogenization and intensification of agronomic systems are essential to ensure the self‐sustainability of the population. In this sense, reforming the Common Agricultural Policy is essential to integrate the conservation of steppe birds into agricultural planning.
Abstract Evidence‐based interventions to reduce wildlife‐caused property losses are essential for achieving sustainable coexistence between humans and wildlife. Since the 1970s, lasers have been used to safeguard various properties, including aircraft, agricultural fields and energy infrastructure. However, their effectiveness has not been quantitatively evaluated using systematic evidence across different scenarios, which limits their broader application. Here, we compiled data from 159 experiments conducted worldwide and used meta‐analytic approaches to evaluate the overall effectiveness of lasers in reducing bird occupancy. To facilitate management‐relevant interpretation, we further assessed its scalability for subgroups of bird taxa, laser characteristics and environmental conditions based on the amount of evidence and statistical support. Our findings revealed the following: (i) although the primary objective of laser deterrents is to prevent property damage, the majority of experiments (96%) quantified effectiveness indirectly based on bird behaviour rather than direct property‐related outcomes; (ii) empirical evidence predominantly originated from wetlands, while data from airports were particularly scarce; (iii) laser operations reduced bird occupancy by 59%, though this deterrent effect gradually diminished after the cessation of laser use, resulting in a statistically non‐significant persistence effect; (iv) Class 3B, green lasers, whether applied manually or automatically, were supported by considerable to moderate evidence for deterring waterfowls and songbirds, especially under low light conditions in natural field settings; and (v) existing evidence does not show clear habituation. Synthesis and applications . Our results indicate that laser deterrents represent a promising non‐lethal intervention for mitigating human–bird conflicts across multiple scenarios. Future research may need to prioritize the development of automated laser applications, incorporate direct measurements of property‐related outcomes and expand experimental evaluations to include underrepresented taxa and high‐impact scenarios. This would strengthen the evidence base for conservation and management applications.
Abstract Monospecific pine plantations are highly vulnerable to disturbance. Promoting oak regeneration through assisted restoration by effective acorn dispersers, such as the Eurasian jay ( Garrulus glandarius L.), could significantly enhance their ecological resilience. However, our ability to design targeted management interventions that harness jay‐assisted oak regeneration is constrained by limited knowledge of how this corvid selects understorey microsites for caching acorns in these plantations. To inform jay‐assisted oak regeneration in pine plantations, we examined how understorey structure influences jay acorn caching behaviour in two ecologically contrasting oaks, Quercus ilex L. and Quercus faginea Lam. We selected three sites within a 55‐year‐old monospecific Pinus pinaster Lam. plantation that differed in density due to thinning. For two consecutive dispersal seasons, we quantified dispersal distances and the microsite caching preferences of jays using acorn radio‐tracking. Jays cached all acorns within the pine plantation and avoided wide natural or artificial gaps. Proportion of cached acorns was similar for both oaks, with no significant differences in dispersal distance kernels. Jays strongly selected large shrubs, mainly Cistus spp., with a tendency to select shrub‐abundant patches and cache acorns closer to pine trunks than expected by chance; these patterns were unrelated to oak species. Jays did not use coarse wood for caching, and caches were no less frequent in furrows or mounds from site preparation to establish the plantation than in undisturbed ground. Between 1.2% and 10.7% of cached acorns produced seedlings that survived their first summer. Synthesis and applications . Our findings show that Eurasian jay dispersal activity depends on specific understorey structures when selecting caching microsites—particularly shrub cover and standing pines. These features could be directly shaped by management to promote assisted natural oak regeneration. By fostering structurally diverse understories, managers can enhance seed dispersal services and accelerate the transition of vulnerable pine monocultures towards more resilient mixed forests.
Abstract As climate change threatens reef‐building coral populations worldwide, there is an increasing interest in restoration to assist the recovery of coral populations. Yet these efforts are limited in scale and therefore, to maximise restoration success, it is crucial to prioritise areas where outplanted corals are most likely to survive and grow. Here, we tested and refined a framework to select sites for coral restoration using survival data of sexually produced corals (spat) from 10 species deployed across diverse habitats in the Great Barrier Reef, Australia. For each deployment site, we extracted data on abiotic and biotic factors, then scored and combined them to compute a single score for each site. We refined the relative weighting of the factors to maximise the variance in spat survival explained by the site scores. We investigated the relationship between spat survival and each of these environmental factors, as well as the combined site score. Finally, we used simulations to quantify the increase in mean spat survival expected if selecting sites based on site scores. Our results show that spat survival generally decreased with increasing cover of benthic organisms, highlighting the important role of competition during early life stages. In contrast, the relationship between spat survival and abiotic factors was species‐specific. Spat survival was positively related to site score in all except one of the species. However, site score predicted only a small fraction of the variance in survival, indicating a spatial mismatch between the broad scales (>100 s m) at which corals must be seeded to support recovery, and the fine scales at which spat survival is affected (<1 m). In our simulations, using site scores improved mean survival in 11 out of 12 species‐by‐reef combinations, although some of the gains were modest. Synthesis and applications . The framework tested can improve the efficiency of seeded‐coral deployments by increasing average survival through site selection for most taxa, thereby reducing the number of deployed spat needed to achieve a target outcome. Species‐specific weighting of factors was unnecessary for many Acropora species, but may be important for other taxa.
Abstract Introduction of invasive plant species has devastated many ecosystems worldwide and led to biodiversity declines. In seasonal wetlands, invasive plants alter community composition, destabilize hydro‐regimes and prevent native species establishment. While there are currently many management approaches, plant functional groups respond differently to each based on phenology and taxonomy. Research has shown that single approaches will not control multi‐species invasions, which is a common occurrence in Mediterranean seasonal wetlands and grasslands. Integrated pest management (IPM) focuses on sustainable land management practices to limit diverse invasive species using a combination of different approaches. Implementing an IPM approach, this study tested whether combinations of herbicide and mowing, with fall grazing, affected native and invasive plant community composition, cover and richness. We assessed this over 2 years at the Yolo Bypass Wildlife Area, California, USA. We found that treatments with two or more combined IPM approaches decreased invasive plant cover and richness and promoted a native plant dominated community. However, treatment effects for invasive plant richness and cover did not carry over into the second year and invasive plants re‐established. These results suggest that an IPM approach can greatly reduce invasive cover; however, annual management is needed to sustain native communities. Synthesis and applications : Our results show that annual invasive plant management is needed to recover and promote native communities. The timing and seasonality of treatment application is also important in determining management success. While fall grazing is conducted annually, this site greatly benefited from the implementation of IPM in the spring to capture plants at vulnerable phenological stages. Using two additional methods (i.e. herbicide and mowing), multiple functional groups were targeted to prevent secondary invasions. These findings provide insight into how management priorities should shift to focus on the depletion of invasive seed banks and prevent reestablishment in areas with multi‐species invasions to promote native plant establishment.
Abstract The number of co‐occurring global change factors (GCFs) is increasing, yet their combined effects on grassland functioning via plant–soil biotic interactions remain poorly understood, especially under contrasting precipitation contexts. Using a long‐term multifactor experiment in the semi‐arid steppe of Inner Mongolia, we established a gradient in GCF number (0–3) through nitrogen addition, phosphorus addition and soil acidification. By integrating plant diversity with the taxonomic, functional and metabolic dimensions of nematode communities, we evaluated their effects on above‐ground net primary productivity (ANPP) and below‐ground ecosystem multifunctionality (BEMF) and tested whether these relationships were reorganized under contrasting precipitation years. Increasing GCF number consistently reduced plant and nematode diversity, simplified nematode food‐web structure and suppressed nematode metabolic activity. ANPP increased with GCF number only in the wet year, whereas BEMF declined in both years. ANPP was primarily and positively associated with nematode metabolic footprints, whereas BEMF was jointly regulated by plant diversity and nematode metabolic footprints. Importantly, these pathways shifted with precipitation context. In the normal year, plant diversity and nematode metabolic footprints jointly sustained both ANPP and BEMF. In the wet year, a functional divergence emerged: above‐ground processes benefited from nutrient inputs, increasing ANPP, whereas below‐ground processes experienced cumulative stress from multiple GCFs, suppressing nematode metabolic footprints and reducing BEMF. Synthesis and applications . Our findings demonstrate that the number of co‐occurring GCFs is a critical but underappreciated dimension of global change, and its ecological consequences depend strongly on precipitation context. Grassland management should consider cumulative nutrient and acidification pressures, maintain plant diversity and use nematode metabolic footprints as indicators of below‐ground functional change. Incorporating soil faunal functional traits into global change assessment frameworks is therefore essential for understanding and sustaining ecosystem multifunctionality under future environmental change.
Abstract Ecological restoration is a global priority, with intergovernmental commitments such as the Kunming‐Montreal Global Biodiversity Framework and the Bonn Challenge seeking to restore the world's forests and their biodiversity. Central to these aims is the restoration of tropical forests, which harbour over half of all terrestrial species. However, one highly diverse and threatened group yet rarely considered in restoration is vascular holoepiphytes: vascular plants germinating and growing on other plants. Despite making up 9% of vascular plant species globally and in places over a third of species locally, they are often overlooked in restoration, omitting a substantial amount of diversity. We address hypotheses regarding timing, population size and age structure of restored epiphyte populations using mechanistic models simulating virtual epiphyte communities within three‐dimensional virtual forests. In epiphyte communities 19 years after introduction, we demonstrate that more species are retained when introducing (a) adult plants into (b) older forest stands. However, different functional groups benefit from nuanced restoration strategies, with higher proportions of faster growing, light‐when‐mature epiphytes in communities introduced into 5‐ to 10‐year‐old forests and at high initial population sizes of 100 individuals per quarter hectare, while short‐dispersing, slow‐growing, heavy‐when‐mature epiphytes are proportionally more abundant with restoration into 20‐ to 40‐year‐old forests. Synthesis and applications . Generally, delayed restoration of adult‐only epiphyte populations into older restored forests improves conservation outcomes. However, restoration can be optimised, initially introducing large populations of fast‐growing, light‐when‐mature species in younger forests followed by the later introduction of slow‐growing, heavy‐when‐mature species in forests older than 20 years. As epiphytes have a slow recolonisation rate, our results identify optimal strategies for restoring a variety of functional groups of a diverse yet difficult‐to‐reestablish ecological guild into regenerating forests.
Abstract Wildlife–aircraft collisions represent a major risk to human safety, wildlife, and aircraft. Active animal hazard management occurs at many airports, but the effectiveness of interventions is rarely analysed. We quantified temporal trends in management effort and effectiveness over 3 years at an airport in Point Cook, Victoria, Australia. For all hazing events (the non‐lethal application of escalating sensory stimuli to displace wildlife from runway‐adjacent critical areas to reduce the likelihood of wildlife–aircraft collisions), we recorded the hazing escalation level applied and wildlife responses to hazing, including non‐responses. We conducted monthly surveys across the airport to quantify numbers, use of critical areas, species richness and diversity. Desirable outcomes were reduced numbers, species richness or diversity, displacement away from areas closest to aircraft, and increased responsiveness of wildlife to hazing, thereby reducing management effort. We used Bayesian mixed‐effects models accounting for seasonal variation and day‐level clustering in event‐level hazing models to examine temporal trends in numbers, effort‐standardised counts, hazing and monthly survey metrics for all species and focal species. Individuals per hazing event, total numbers per monthly survey and diversity remained stable, but hazing events and monthly surveys indicated decreasing use of runway‐adjacent critical areas. The proportions of individuals and hazing events occurring in critical areas decreased, the escalation required to displace wildlife decreased and both pre‐hazing distances and post‐hazing flight distances shortened over time. These changes imply that management displaced wildlife from the critical areas without reducing their overall use of the airport, suggesting local‐scale rather than broad‐scale displacement. Management efficiency also increased, as lower‐intensity hazing was increasingly sufficient to displace wildlife. Synthesis and applications . Most wildlife–aircraft collisions occur near airports during take‐off and landing, so reducing wildlife use of runway‐adjacent critical areas provides a practical proxy for exposure to wildlife–aircraft collisions. Routine indicators from hazard management records—the proportion of individuals in critical areas, hazing escalation level and flight distances—captured temporal change in wildlife use of critical areas and management effort, showing that operational datasets can yield management‐relevant insights. Airports could apply similar indicators to assess whether interventions shift wildlife away from critical areas and prioritise low‐intensity, coexistence‐focused management over broad suppression.
Abstract Invasive rodents remain a major source of environmental damage worldwide. Sex‐biasing gene drives may provide an alternative to toxicant‐based eradication strategies. Risk assessments for gene drives will rely partially on models, which must account for intraspecific variation in the ecological and life‐history characteristics of target populations. Dispersal patterns and mating system characteristics in particular are expected to impact drive spread and suppression outcomes, though empirical data on natural populations are lacking. We developed a stochastic metapopulation model implemented using numerical simulations that simulates the introduction and spread of male‐biasing X‐Shredder or female‐biasing Y‐Shredder gene drives to suppress an island population of house mice ( Mus musculus ). Our model includes parameters for mating system complexity, sperm competition, dispersal frequency and distance, as well as several features related to release strategy and drive efficiency (shredding efficiency for both drives, homologous site cutting efficiency for Y‐Shredder drives). We found that both drive strategies are capable of complete population eradication within ~15–35 years depending on parameterization. Drive efficiency had the strongest impact on eradication probability and timing across both drive types. Increasing dispersal frequency usually improved the probability of successful eradication and reduced the time required to achieve eradication, though we identified several exceptions to this trend. Polyandrous mating limited the success and speed of X‐Shredder drives, while the effect of polygynous mating varied for Y‐Shredder drives, improving eradication probability across certain parameter combinations at lower dispersal frequencies when cutting efficiency exceeded shredding efficiency and shredding efficiency remained above a minimal threshold. Across parameter space and drive strategies, ‘chasing’ events, in which wildtype individuals repeatedly recolonize eradicated areas, were common and often prevented successful eradication at low dispersal frequency. Dispersal behaviour exhibited a strong influence on the spatial characteristics of recolonization and chasing events. Synthesis and applications . Though drive efficiency was highly influential to model outcomes, such parameters will likely be known prior to any experimental gene drive introductions. We conclude that understanding the ecological and life‐history characteristics specific to target populations will be critical to accurately predict gene drive outcomes and inform risk assessments.
Abstract Freshwater ecosystems are hotspots of biodiversity and contribute significantly to food security. Yet freshwater habitats throughout the world remain plagued by overfishing, which depletes populations and diminishes provisioning of ecosystem services. There is growing interest in the use of freshwater protected areas (FPAs), which are freshwater ecosystems managed under long‐term fishing bans and conservation‐oriented regulations, to promote ecosystem recovery. Yet empirical evidence on the efficacy of FPAs indicates that ecological recovery can be complicated by non‐native species, which may also benefit from reduced harvest pressure and improved habitat conditions. To evaluate effects of targeted fish removals (TFRs) under fully implemented FPAs, we conducted exhaustive field surveys across five Chinese lakes with and without removal efforts and assessed multiple dimensions of fish assemblage diversity. Results showed multidimensional diversity metrics for native fishes improved significantly in FPAs with TFRs (e.g. non‐native fish removals in invasion hotspots), while these same metrics declined in control lakes. Moreover, TFRs appeared to strengthen top‐down regulation and alleviate eutrophication, as indicated by altered trophic cascade relationships and reduced phytoplankton biomass (PB) in FPAs with TFR. Synthesis and applications. Our results indicate combining FPAs with TFRs is essential to achieve effective biodiversity recovery in these ecosystems. This integrated strategy should be prioritized in invasion‐prone or eutrophic systems, where passive protection alone is unlikely to deliver desired ecological outcomes.
Abstract Grasslands are important ecosystems that sustain productive pastoral enterprises and support multiple ecosystem functions. Yet grasslands are threatened by shrub encroachment, the transformation of grass‐dominant states to those dominated by woody plants. The extent to which encroachment initiates abrupt changes in ecosystem functions, and the major drivers of these changes, remain elusive. We quantified five ecosystem functions (i.e. plant productivity, soil stability, soil carbon storage, soil decomposition capacity and soil nutrient cycling), and calculated trade‐offs among them across 102 sites along a gradient in shrub cover. We assessed the response of ecosystem functions to increasing encroachment and explored the relative importance of biotic and abiotic factors on ecosystem functions in encroached grasslands. Plant productivity exhibited a non‐linear, bimodal response to shrub encroachment with two encroachment thresholds. Productivity declined sharply from 0% to 3% shrub cover (grass‐dominant stage), stabilized at 3%–25% cover (grass‐shrub transitional stage) and decreased substantially beyond 25% shrub cover (shrub‐dominant stage). Trade‐offs among productivity and ecological functions were stage dependent, being intense in the grass‐dominant stage but shifting towards synergy in the transitional and shrub‐dominant stages. Intensified encroachment decoupled the effect of above‐ and below‐ground species richness on functions. Productivity was positively related to below‐ground invertebrate richness under grass dominance, but became driven by above‐ground plant richness and soil bulk density in the grass‐shrub transitional stage as encroachment intensified. Synthesis and applications . Our results demonstrate the non‐linear response of productivity to shrub encroachment and highlight the importance of incorporating encroachment thresholds into grassland monitoring and management. Our study shows that trade‐offs among productivity and ecological functions are strongest during the grass‐dominant stage, suggesting that management aimed at maintaining multiple ecosystem functions should be prioritized during the early stages of encroachment. Moreover, intensified encroachment decoupled the effects of above‐ and below‐ground species richness, indicating that maintaining below‐ground species richness is critical in the grass‐dominant stage when shrubs are sparse. The results highlight the importance of initiating brush management interventions at the early stages of encroachment (~3% shrub cover) and provide a scientific basis for guiding the timing and optimization of shrub removal strategies.
Abstract Soil denitrification is strongly linked to soil nitrogen availability and influences nitrate leaching and greenhouse gas emissions. In turn, it can be regulated by ecosystem productivity through plant nitrogen uptake and organic matter inputs. However, the specific effects of tree diversity on soil denitrification and the underlying mechanisms remain poorly understood in forest ecosystems. Here, we investigated the effects of tree species richness (across five levels: 1, 4, 8, 16 and 32 species) and the corresponding functional structure on soil denitrification through a large biodiversity experiment in young subtropical forests (3‐year‐old). Our results revealed a unimodal relationship between tree species richness and denitrification potential, with the peak at four species. The structural equation model indicated that tree species richness was positively associated with the functional dispersion of leaf dry matter content, which in turn increased ground basal area, thereby promoting denitrification potential by enhancing soil water‐filled pore space, elevating the abundance of the nirK gene and reducing the soil C:N ratio. Additionally, the community‐weighted means of root tissue density and specific leaf area positively and negatively influenced soil denitrification potential, respectively. Synthesis and applications . Our results suggest that soil denitrification is more pronounced in young forest communities characterized by high productivity and dominated by resource‐conservative species with high root tissue density and low specific leaf area. We recommend that forest managers prioritize high functional trait diversity rather than tree species richness to maximize niche complementarity in planted forests, an approach that would improve both economic and ecological benefits. These findings provide a foundation grounded in evidence for integrating biodiversity, nutrient cycling and selection principles based on traits into afforestation and stand transformation.
Abstract The frequency and severity of natural disturbances and forest harvests are changing in many temperate and boreal forests worldwide, at a time when regional surveys suggest deficiencies in tree regeneration. This combination suggests the utility of assessing how regeneration existing prior to disturbance (i.e. advance regeneration) translates to forest recovery following recent disturbances. We used repeated plot measurements from nationwide forest inventory data to link advance seedling regeneration to post‐disturbance seedling abundance and sapling recruitment across forests of the northern USA an average of 14.3 years following natural disturbances and forest harvests. Three metrics were considered: regeneration abundance, species richness and compositional similarity to the pre‐disturbance mature tree layer. Random Forest models were used to predict post‐disturbance regeneration response as a function of advance regeneration, pre‐disturbance stand attributes, disturbance type and severity, terrain and geography. Advance seedling regeneration was moderately correlated with post‐disturbance sapling recruitment and seedling abundance, indicating that challenges in advance regeneration do tend to carry over to challenges in post‐disturbance regeneration. Regeneration challenges following natural disturbance were more acute compared with harvesting. Higher disturbance and harvest severity were associated with more robust post‐disturbance sapling recruitment and, to a lesser extent, seedling abundance. Other influences on post‐disturbance regeneration included climate, geography, loss of particular tree genera (especially Populus ), subsequent harvesting and understory plant cover. Synthesis and applications : Our work establishes that previously observed challenges in advance regeneration contribute to poor recovery following harvests and natural disturbances in northern USA forests. Shifts towards lower severity harvesting in the region may be exacerbating post‐disturbance regeneration challenges, ultimately leading to low tree species richness and novel composition. Our results indicate that recovery from natural disturbance may be improved through judicious post‐disturbance management, including harvesting that focuses on improving regeneration environments while also protecting important post‐disturbance structure, like surviving trees and downed wood.
Abstract Palaearctic grasslands are heavily threatened by land‐use changes that lead to degradation and habitat loss. Thus, successful grassland restoration for vegetation and wildlife is urgently needed. Butterflies, as sensitive indicators, could provide a holistic view of restoration outcomes and landscape effects. We surveyed 121 restored, 33 positive (ancient, species‐rich) and 33 negative (ancient, degraded) reference sites in northern, central, and southern Germany to analyse how recovery of butterflies is affected by site and landscape variables. Restored grasslands cover various restoration methods, that is, seeding of cultivar or regional seed mixtures, transfer of directly harvested seeds from suitable donor sites, or management adaptation without plant species introduction. Landscape effects were analysed at different scales (300, 600, 1200 m). We defined target butterflies as forb‐feeding grassland specialists with low dispersal abilities, supplemented by threatened grass feeders and burnet moths. Total butterfly species richness, total abundance, and target abundance on restored sites were similar to positive, but higher than on negative references. However, target species richness and Hill–Simpson diversity on restored sites did not reach the level of positive references. Of all the restoration methods, sowing of cultivar seed mixtures was least successful and the failure was more pronounced for target species. Re‐establishing the characteristic plant species richness was most important for butterflies, whereas landscape variables played a subordinate role. However, total butterfly abundance was promoted by higher grassland cover within 1200 m, and total Hill–Simpson diversity increased with grassland plant species richness. Target butterfly recovery was lower in older restored grasslands than in younger ones. Synthesis and applications . The results indicate that successful restoration of grassland vegetation and butterflies is strongly linked. To fully restore target butterfly assemblages, future grassland restoration should aim to re‐establish and maintain plant species‐rich habitats by implementing high‐quality restoration methods. Successful grassland restoration promotes butterflies in different landscapes. However, further efforts are needed to restore butterfly assemblages close to the levels of favourable reference sites, for example by increasing the cover of high‐quality grasslands in the surroundings. Although restoration is successful, preservation of species‐rich ancient grasslands should have the highest priority. Read the free Plain Language Summary for this article on the journal's blog .
Abstract Structured coastal habitats serve as vital fish nurseries globally, yet the role of biotic and abiotic factors in shaping this function remains unclear. Understanding these relationships will allow more informed conservation and restoration decisions and effective communication of their anticipated effects on fish production. We conducted a meta‐analysis of 102 studies (2002 responses) to evaluate the potential drivers of fish recruitment enhancement (RE), defined as the relative increase in young‐of‐year fish abundance in structured vs. unstructured bottom, in North American salt marshes, oyster reefs and submerged aquatic vegetation (SAV). All three habitats significantly enhanced fish recruitment, with SAV and salt marshes exhibiting greater RE than oyster reefs. Restoration increased fish recruitment in all three habitats (130%–180%), but only restored marshes and oyster reefs—not SAV—achieved RE comparable to their natural counterparts. Habitat characteristics were consistently influential predictors of RE across habitat types. In SAV, shoot cover and biomass were positively associated with fish recruitment, with RE being 295% higher in SAV with dense (~80%) compared with sparse (~20%) shoot cover. Fish recruitment increased with oyster cover but declined at greater reef heights, with low (<0.2 m) and moderate (0.2–0.5 m) relief reefs each supporting 215% and 110% greater RE than high relief reefs (>0.5 m). Proximity to SAV and oyster reefs increased RE in salt marshes by 170%; however, this positive effect was not reciprocated in SAV and oyster reefs near marshes. RE remained consistent across temperature and salinity gradients, whereas it was strongly influenced by tidal regime in salt marshes and SAV. Synthesis and applications . Our findings underscore the importance of habitat attributes and physical settings as the key predictors of fish enhancement across threatened coastal nurseries of North America. Restoration and management efforts should aim to optimize these factors to maximize fish recruitment potential amid ecosystem degradation.
