Agriculture, Ecosystems & Environment

Polycultures have long been practiced in traditional agriculture, yet their ecology-based benefits have remained underexplored. Here, under realistic conditions, we experimentally evaluated the productivity and ecological interactions in cultivated milpa, a traditional Mesoamerican polyculture of maize, squash and beans, using a substitutive design in which total plant density was held constant while varying species composition. Specifically, we asked whether productivity gains arose through complementary or selection effects, and whether these gains were associated with changes in arthropod communities and herbivory. We additionally evaluated whether prior cultivation influenced maize performance in the following season. Milpa plots produced significantly higher total yields, more than 2.6 times those of monocultures, despite poor bean performance. In particular, squash and maize equivalent yields increased approximately threefold. We found that these improvements were mainly explained by complementary effects rather than selection effects. Arthropod communities responded in species-specific ways to crop diversity, with predator abundance tracking herbivore presence. However, no consistent patterns emerged between herbivore load, predator abundance and plant damage, suggesting that belowground plant interactions may play a more important role than top-down herbivore control in explaining complementarity effects. In the following season, maize yield increased by [~]30% in plots previously planted with squash or beans, with milpa plots showing intermediate responses. These findings demonstrate that milpa can substantially enhance productivity while generating benefits that extend into the advantages and soil into the following growing season. Overall, our results suggest that complementarity among crops is the primary driver of productivity in milpa under low-input conditions.

Surges in food availability create localized but intense foraging opportunities, often attracting multi-species consumer groups. Agricultural practices can trigger these surges, prompting bird associations. However, the strength and duration of the association, as well as its drivers, remain unclear. This study examines waterbird association with harvesting and ploughing events in rice fields. The duration and magnitude of these associations were determined and three hypotheses addressed to explain them: (1) increased food availability, (2) enhanced foraging success and (3) reduced time allocated to vigilance. Waterbird counts and GPS tracking revealed strong associations with management events. Bird numbers spiked during events but declined within one to two days. Food availability (and soil penetrability) increased significantly during events - crayfish and rice during harvesting, worms and soil penetrability during ploughing - supporting Hypothesis 1. However, this did not improve foraging performance (intake rate, foraging success), rejecting Hypothesis 2. Higher competition, interference or kleptoparasitism in these large mixed-species flocks may offset increased food availability benefits. Alternatively, functional responses of target species may limit prey intake due to physiological or behavioural constraints. Hypothesis 3 was also unsupported, as birds did not reduce vigilance. It is plausible that birds may be drawn to events by the perception of a feast, not actual benefits. Gregariousness and foraging behaviour by local enhancement may explain such associations. Results highlight the complexity of bird responses to food surges while suggesting waterbirds in rice fields maintain stable foraging performance during agricultural management events and otherwise, indicating resilience to agricultural timing shifts.

Smallholder farming systems in sub-Saharan Africa are constrained by declining soil fertility, erosion, and rising fertilizer costs, creating an urgent need for scalable inputs that sustain yields while maintaining soil health. While there is some evidence that microbial inoculants may offer a promising complement to conventional fertility management, field-scale evidence in tropical cereal and tuber systems remains limited. Here, we evaluated a multi-species inoculant composed of 20-22 Bacillus and Streptomyces species on potato and maize across four sites in Rwanda over two growing seasons (2025A and 2025B). Treatments included the inoculant applied at two rates (150 and 250 g ha-1), both alone and in combination with standard fertilization (inorganic fertilizer plus manure), alongside untreated and fertilized controls. Co-application of the inoculant with standard fertilization increased yield and plant biomass beyond fertilization alone, with gains of 6-51% for maize and 3-58% for potato. However, while the inoculant applied alone outperformed untreated controls, it generally did not match standard fertilization. Responses were strongest and most consistent for large-grade potato tubers, and application rate interacted with crop type, whereby the lower dose maximized marketable tuber yield, while maize showed a positive dose-response for grain and biomass. Yield increases were not accompanied by reductions in crop nutrient density, which was instead governed by site-level differences. Altogether, these results indicate that multi-species microbial inoculants are an effective complement to existing fertility practices that may offer, pending further research, a potential pathway to partial fertilizer replacement while sustaining productivity and nutritional quality in smallholder tropical agriculture.

Over recent decades, numerous studies have compared agricultural productivity across different management systems and environments, with increasing attention to the stability of crop yields. Yield stability is a key component of agroecosystem resilience under global change, yet it remains unclear whether some cropping systems are more stable than others. The debate over organic farming is particularly heated, as some evidence indicates that organic systems are less stable, while other evidence suggests the opposite. Here, we develop a conceptual and statistical framework for comparing crop yield stability across agricultural systems that explicitly accounts for a parametric function relating inter-annual yield standard deviation to mean yield value. Using a new global dataset of long-term field experiments spanning multiple crop species and environments, we show that the fitted functions relating yield standard deviation and mean yield value obtained for organic and conventional cropping systems share several important similarities. For both systems, the yield coefficient of variation (CV) significantly decreases with mean yield, and most of the difference in yield stability between conventional and organic systems is explained by differences in mean productivity. As a consequence, the CV of the two systems becomes similar as the difference in average efficiency narrows. Our framework reconciles apparently conflicting results in the literature and provides a more robust basis for comparing stability across cropping systems.

Understanding the relationships between soil macrofauna and decomposition is crucial for predicting how land-use change impacts ecosystem function in fragmented systems. This is because soil macrofauna affect decomposition and also respond to the changes in abiotic conditions across habitat gradients. This study investigates edge effects on the macrofauna contributions to decomposition across forest-field ecotones. We used bait lamina assay to quantify aboveground and belowground feeding activity of soil macrofauna in Autumn 2025 in three deciduous forest-old field ecotones and one coniferous forest-old field ecotone, in Southwestern Ontario, Canada. Vegetation diversity and composition, LAI and soil characteristics (i.e., soil organic matter, pH, temperature and moisture) were measured at each plot along the ecotone. Pitfall trap data collected in Summer 2025 at the same sites were used to characterize macrofauna communities. We used generalized linear mixed effects models to estimate the effect of distance to edge, site, and depth into the soil on bait lamina consumption and soil macrofauna, with transect nested within site as random effects. Consumption activity increased with distance into the forest from the field, with the edge representing an intermediate; and, decreased with increasing depth into the soil. In contrast, soil macrofauna abundance, especially isopods, decrease with distance into the forest from the field. These trends varied significantly across sites, so that consumption activity and abundance sometimes remained constant across the ecotone (i.e., site x distance interaction). The results demonstrate that macrofaunal contributions to bait consumption varied along the ecotone, shaped by interacting environmental gradients and shifts in community composition unique to each site.

Cropland abandonment is a widespread socio-ecological transition that can generate heterogeneous ecological outcomes, including opportunities for vegetation recovery as well as the accumulation of invasive alien plants (IAPs). Understanding broad-scale correlates of IAP richness in abandoned croplands is challenging because published studies differ in sampling design, spatial extent, and reporting detail. To provide an exploratory national-scale synthesis, we compiled literature-derived occurrence records of 57 IAP species reported from abandoned croplands across China and examined study-level recorded richness using generalized linear mixed models (GLMMs) with province as a random effect. Fourteen socio-economic and environmental predictors were screened for multicollinearity and standardized, and the number of Higher Education Institutions (HEIs) was included as a proxy for potential sampling-effort variation. Asteraceae accounted for 43.9% of recorded species, and more than 70% of taxa were classified as high-risk invaders (Levels 1-2). Recorded richness exhibited a pronounced southeast-northwest gradient, with higher values in economically developed coastal provinces. In the exploratory GLMM, regional GDP (IRR = 1.67, p < 0.05) and mean annual temperature (IRR = 1.49, p < 0.05) were positively associated with recorded richness, whereas other environmental, accessibility, soil, and sampling-effort variables showed no detectable associations. Model diagnostics indicated no evidence of overdispersion, zero inflation, or residual spatial autocorrelation. Given the heterogeneous nature of literature-derived data and the small number of study units, these results should be interpreted as broad-scale correlational patterns rather than causal drivers. The findings highlight regional socio-economic context and climatic conditions as key correlates of recorded IAP richness in abandoned croplands and provide an initial baseline for understanding invasion patterns in post-agricultural landscapes undergoing rapid land-use transitions..

Frugivorous insect larvae are dependent on fruiting plants for development, leading to complex host-parasite interactions that may be influenced by many factors at various scales. We compared the relative effects of factors at the individual, neighborhood, and landscape scales in forest patches. Our results suggest that in areas like upstate New York, where agricultural land uses are dominant, individual scale factors are the most influential. Specifically, parasitism increased with host fruit crop size, but was not associated with host species richness or proximity to forest edge. Notably, the most parasitized hosts were non-native species, including Frangula alnus Mill. (Glossy Buckthorn), indicating a potential role of invasive species to shape host-parasite interactions in our system. Our results underscore the importance of host-specific traits in structuring parasitism patterns and suggest management could consider both the ecological context of host traits and the influence of invasive species at multiple scales.

Commercial inoculants based on associative diazotrophs and methylotrophic bacteria, and bios-timulant programs, are marketed for broad use in cereal and fiber production, yet most field deployment occurs over already adequate mineral fertilization, where their marginal value is poorly quantified. We reanalyzed three randomized complete-block trials conducted at commercial scale in the Brazilian Cerrado (Sao Desiderio, Bahia) under full conventional fertilization: corn (seven treatments, four blocks; 2023/24), cotton (five treatments, four blocks; 2024/25), and soybean (four treatments, six blocks; 2024/25). Treatments evaluated Azospirillum brasilense, Methylobacterium symbioticum, Bradyrhizobium spp., a Bacillus phosphorus solubilizer, and biostimulants, applied via seed and foliar routes. Beyond conventional analysis of variance, we fit mixed models with block as a random effect, quantified effect sizes and coefficients of variation, computed the minimum detectable difference at 80% power, and applied two one-sided equivalence tests (TOST) against the untreated control at margins of plus or minus 10% and 15% of control yield. No treatment produced a statistically significant yield gain in any crop (all p greater than 0.8; fixed and mixed models concordant). In cotton, the best-powered trial (coefficient of variation 6%), all treatments were statistically equivalent to the untreated control within a 10% margin, an affirmative negative result. In corn and soybean the trials were underpowered (minimum detectable difference 21 to 26% of control), so non-significance is not equivalence; corn showed non-significant numerical gains up to 8.9% with phosphorus-solubilizer and methylotroph combinations that could not be excluded. Foliar nutrient concentrations (single composite per treatment, descriptive) showed no enrichment in inoculated treatments. Under standard fertilization, these commercial inputs delivered no detectable agronomic value where the data were adequately powered to test it. The results clarify the low empirical bar that current associative-fixation products meet in the field and, by extension, the agronomic threshold that engineered, plant-controlled nitrogen fixation must exceed to be useful.

Modern agriculture is characterized by substantial fertilizer nitrogen (N) losses from soils, resulting in low crop N-use efficiency. Biological nitrification inhibitors (BNIs) are studied as a strategy to improve N retention in soils by suppressing nitrification. However, the impacts of applying exogenous BNIs to crops with unknown intrinsic BNI capacity remain poorly understood. In this study, we evaluated the impacts of adding three BNIs (methyl 3-(4-hydroxyphenyl) acrylate [MHPA], 6-methoxy-2(3H)-benzoxazolone [MBOA], and limonene), their mixture, and the synthetic nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on barley (Hordeum vulgare L.) growth, plant and soil N dynamics, and soil microbial communities. Using a rhizobox system with planted and bare-soil compartments, combined with 15N isotope tracing and molecular microbial community analyses, we assessed the spatio-temporal dynamics of N transformations, losses, plant N uptake, and microbial community responses in an alkaline agricultural soil. Independent of inhibitor application, the applied fertilizer N was lost primarily through NO- leaching (3-9% of the applied N). In contrast, N2O emissions represented only 0.001-0.028% of the applied N and varied with inhibitor type. MHPA increased dissolved inorganic N soil pools without affecting plant biomass or 15N uptake or strongly shifting microbial community composition. MBOA reduced NO3- concentrations in soil pore water without influencing plant growth or N uptake but shifted soil microbial community composition. In contrast, limonene reduced plant growth and 15N uptake and most significantly altered microbial community composition, without significantly changing N availability. Applying a BNI mixture, as well as limonene alone, was detrimental to plant growth and 15N uptake. DMPP showed only minor effects on N pools, plant growth, plant N uptake and microbial community composition. Overall, our results reveal both the potential and limitations of exogenous BNI application for improving N retention in crop systems.

Low-density polyethylene (LDPE) microplastics (MPs) are the most frequently sampled type of microplastic in agricultural soils, potentially threatening the soil environment. The majority of MPs that have been investigated are produced from standard polymer formulations, for which the nature of the added compounds is often unknown. Furthermore, standard ecotoxicity tests performed on model species are insufficient for assessing the ecological consequences of MPs contamination in soil. This study examined the responses of multiple keystone species to exposure to MPs in interaction with various additives. No significant effects on their growth were observed when organisms were exposed to MPs alone. However, significant reductions in growth occurred when organisms interacted within uncontaminated soil: the introduction of plants reduced potworm biomass by 49 {+/-} 4.1 % while the introduction of potworms reduced earthworm biomass by 41 {+/-} 5.2%. In MP-contaminated soil containing plants, the average individual biomass of potworm increased significantly from 1.16 {+/-} 0.09 mg in uncontaminated conditions to 2.01 {+/-} 0.27 mg. This suggests that MPs limited the negative effects of interactions. Similar patterns were observed for the potworm-earthworm interaction. MPs containing the highest concentrations of additives induced the strongest biological responses. Analysis of soil parameters revealed that these impacts are likely linked to the disruption of nitrogen cycling. Therefore, it is imperative to comprehensively address the interactions between soil organisms and the influence of additives on plastic ecotoxicity in order to better assess the ecological risk posed by MPs.

Nepal's rangelands provide multiple benefits, including support for pastoral livelihoods and alpine biodiversity, regulation of water and soil nutrients, and sequestering carbon. Climate change and anthropogenic pressures are altering these rangelands, leading to vegetation and biodiversity change. However, national-scale assessments of rangeland change are limited in Nepal. This study quantified rangeland changes at multiple spatial scales and assessed the climatic and non-climatic drivers of rangeland change. About 80.7% of Nepal's high-altitude rangeland (> 2,000m) outside protected areas showed no significant change. Among areas exhibiting significant annual maximum NDVI trends, 383,281 ha (18.6%) showed positive and 14,702 ha (0.7%) showed negative trends, corresponding the ratio of increase in vegetation greenness and decline in vegetation greenness to 26:1. Climate predicted positive trends covered 627,184 ha (30.5%), whereas residual trends caused by non-climatic drivers covered 94,656 ha (4.6%). Climate induced negative trends covered 47,609 ha (2.3%) while residual trends were observed in 6,260 ha (0.3%). Negative trend pixels were concentrated mainly within the 3,000 to 5,000 m elevation band, with Karnali Province recording the highest proportional climate predicted decline in vegetation greenness (3.4%). At the municipality scale, rangeland change showed no significant relationship with grazing pressure derived from gridded livestock data, suggesting that grazing pressure alone did not explain the non-climatic vegetation signal. These spatially explicit, nationally consistent results identify where rangeland change is occurring and help distinguish climatic and non-climatic drivers of rangeland vegetation change, providing evidence to support targeted rangeland management under Nepal's federal governance structure.

Forests are essential to the global carbon cycle with light use efficiency (LUE) as a key parameter for assessing carbon sequestration capacity. However, the variations and drivers of LUE remain inadequately understood. Using remote sensing data, we analyzed global LUE patterns across five forest types and identified the main drivers. The global average annual LUE of forests is 0.93 {+/-} 0.36 g C MJ-1 during the period 2001-2022, with an increasing trend of 0.0034 g C MJ-1 yr-1. Among forest types, evergreen broadleaf forests exhibited the highest LUE, followed by evergreen needleleaf forests. Deciduous broadleaf forests and mixed forests showed similar levels, while deciduous needleleaf forests exhibiting the lowest LUE. Variations in LUE were jointly driven by plant traits and climatic conditions, with generalized linear models explaining 86% and 98% of spatial and temporal LUE variations, respectively. These findings highlight the critical role of plant traits and climate in shaping forest LUE, providing insights for enhancing carbon cycle models and informing forest management strategies in the context of global change.

The reintroduction of extinct or endangered species to restore ecosystem function is an essential aspect of rewilding. The Wilder Blean Project at West Blean and Thornden Woods in Canterbury, UK, is committed to rewilding natural processes and enhancing biodiversity in one of England's oldest and largest areas of ancient woodland. The introduction of European bison (Bison bonasus) is an important part of the project. However, how the reintroduction of large herbivores influences local biodiversity and ecosystem functions during the early stages of rewilding remains poorly understood. Soil samples were collected from the same sampling sites before and two years after bison were reintroduced and profiled by metagenomic sequencing using Oxford Nanopore Technologies sequencing platforms. The results showed that the alpha diversity of soil organisms did not change significantly before and after the introduction of European bison, while beta diversity showed modest shifts in community composition. The relative abundance of some nitrogen-fixing and photosynthetic microbial genera showed declines in the 2024 Bison Area, while the mycorrhizal fungus genus Rhizophagus was significantly less abundant than in the 2024 Control Area. Despite relatively stable taxonomic diversity, functional composition differed significantly between the 2022 and 2024 Bison areas and among the 2024 rewilding treatments, revealing a decoupling between taxonomic diversity and functional composition. Amino acid synthesis pathways and carbon metabolism pathways were significantly enriched. These findings highlight the potential of long-read Oxford Nanopore metagenomics to reveal functional shifts that may not be apparent from taxonomic diversity alone. Although these early-stage responses cannot yet predict long-term rewilding trajectories, continued longitudinal monitoring integrating microbial, soil physicochemical, and ecosystem-level measurements will be essential to determine the persistence and ecological significance of these functional shifts.

Maximising ecosystem service (ES) benefits while minimising ecosystem disservices (EDS) is essential for ecological intensification in annual crop systems. Yet ecosystem disservices are often underreported in the scientific literature, potentially biasing how agroecosystem functioning is understood. To test this, we built a predicted network of plausible links between ecosystem service providers (taxa or functional groups that can deliver ecosystem services or disservices), and the ES or EDS they may provide. We then compared this with a realised network based on systematic Scopus searches of annual crop literature. The predicted network contained 47 nodes and 103 links, whereas the realised network contained 33 nodes and 58 links, representing declines of 29.8% in nodes and 43.7% in links. Overall connectivity declined, especially for highly connected nodes, and four of the nine predicted disservice nodes were absent from the literature. ES links were more likely to be documented than EDS links, and EDS links were three times more likely to be absent. Across all links, ES were reported in 6.6 times more papers than EDS. Projected networks, which map indirect connections by linking ES directly to EDS if they share common providers, showed that these bundled interactions were strongly reduced, obscuring multifunctionality and trade-offs. This systematic underrepresentation of EDS, reflecting a cognitive bias, can inflate perceived benefits, distort the evaluation of key taxa and interactions, and create unrealistic expectations about intervention outcomes in biological crop protection. Addressing EDS alongside ES is therefore essential for more balanced assessments of crop-system management and better-informed decisions.

Metabolites from Plantago lanceolata (plantain) biomass have been linked with biological nitrification inhibition (BNI) in soil. After grazing, leaf metabolite chemistry is altered via digestion, and a suite of secondary metabolites are then delivered onto soil via dung and urine. The purpose of this study was to establish if urine from sheep grazed on plantain had BNI activity when added to pasture soil, and to identify the metabolite profile(s) that most likely contribute to the BNI effects observed. Groups of sheep (n=5) were grazed on one of nine different plantain cultivars in autumn and spring with analysis of leaf material, urine, soil incubation and BNI bioassay data used to identify potential metabolite candidates implicated with BNI. The urinary nitrogen and metabolite composition of sheep fed plantain varied significantly between cultivars and season. After 28 days of incubation, all soil microcosms treated with plantain-derived urine had up to 35% less nitrate than comparative ryegrass urine controls in both seasons, except one in autumn. The key phytochemistry associated with lower soil nitrate concentrations was phenylethanoid and iridoid glycosides resulting in a higher output of glucuronidated, methylated and sulfated secondary metabolites in the urine. Among 19 secondary metabolites identified in the urine, hydroxytyrosol-related metabolites as well as catechol glucuronide, 2-methoxyphenyl sulfate and guaiacol-{beta}-D-glucuronide appear to be the most likely target compounds with respect to the BNI effects observed. Variation in metabolites from different plantain cultivars affected the ratio of metabolite derivatives in urine, which ultimately affected soil nitrification rates. Cultivar phytochemistry is therefore an important consideration with respect to BNI under urine patches. HighlightsO_LISheep grazing different plantain cultivars had different urine compositions C_LIO_LIUrines elicited biological nitrification inhibition (BNI) in soil and in vitro C_LIO_LIDifferent BNI response was related to differential expression of urine metabolites C_LIO_LIKey urine metabolites associated with BNI are derived from glycosidic compounds C_LI

The use of nitrogen (N) fertilizers to meet global food demands is expected to continue rising. However, up to 70% of N applied to agricultural soils is lost through microbially mediated processes such as nitrification. Inhibiting nitrification is thus a key strategy to reduce N losses and improve fertilizer N use efficiency. Various plant-derived compounds, termed biological nitrification inhibitors (BNIs), have been shown to reduce accumulation of nitrification products, intermediates, and byproducts (nitrite, nitrate, nitric and nitrous oxides). However, the mechanisms by which BNIs affect nitrifiers, along with their specificity and persistence in soil are not well understood. Here, we evaluated the effects of three BNIs: methyl 3-(4-hydroxyphenyl) acrylate (MHPA), 6-methoxy-2(3H)-benzoxazolone (MBOA), and limonene, on ammonia-oxidizing, total microbial, and fungal communities in two soils with contrasting pH. Their persistence in each soil was also evaluated. Although ammonia-oxidizing archaea initially dominated nitrifier communities in both soils, their bacterial counterparts significantly increased after mineral N addition but also were more sensitive to BNI application. Limonene and the synthetic inhibitor DMPP stimulated ammonium immobilization, as total soil mineral N was significantly reduced. Limonene and MHPA had the strongest off-target effects, increasing the relative abundance of hydrocarbon-degrading bacteria and potential fungal pathogens, respectively. In contrast, MBOA inhibited nitrification with minimal off-target effects. Among the tested BNIs, MBOA was also the most persistent in the high-pH, high-nitrification-rate soil. Our results show that MBOA is a promising biological inhibitor and highlight the importance of understanding BNIs ecological effects to develop targeted and sustainable N management strategies.

Biochar amendments are increasingly applied to improve soil physical functioning and support carbon dioxide removal, but their effects on intrinsic soil thermal properties remain poorly characterised. We conducted the first global systematic meta-analysis of 19 independent studies, 231 control-biochar comparisons, and 529 property-specific effect sizes to test how biochar changes soil heat transfer and storage. Biochar reduced thermal conductivity by 17.6% (95% CI, -22.7 to -12.2), thermal diffusivity by 11.0% (-14.5 to -7.3), and volumetric heat capacity by 8.3% (-12.3 to -4.1). Gravimetric heat capacity showed no significant overall response (+3.3%; -7.6 to 15.4) but was supported by fewer studies. Negative responses were directionally consistent for thermal conductivity, diffusivity, and volumetric heat capacity. Moderator analyses showed that responses were most consistently associated with post-application bulk density and changes in bulk density, while application rate modulated response magnitude and soil texture constrained context dependence. Co-variation among thermal conductivity, thermal diffusivity, and volumetric heat capacity matched expected physical dependencies, indicating coordinated structural reorganisation rather than independent shifts in isolated parameters. These estimates describe intrinsic conductive and storage properties; field-scale soil temperature responses may also be modified by albedo, evaporation, vegetation, and surface energy balance. Improved integration of soil thermal measurements with moisture dynamics, structural changes, and carbon cycling is essential to accurately represent biochar effects in soil and land-surface models.

Plants form holobionts by associating with diverse microbiota. Self-organization gives rise to emergent properties of the holobiont, such as increased resistance to pathogens. However, the local factors contributing to the self-organization are not well understood. We hypothesized that nematode communities and their associated microbiota govern the rhizobiome of the model plant holobiont tomato in terms of its suppression of root invasion by the parasite Meloidogyne hapla, and that the soil legacy influences the suppressive potential mediated by these biota. In pot experiments, a resistant tomato holobiont was favored by assembly in the presence of a nematode community conditioned by tomato plants, compared to oilseed rape or fallow soil. Nematode communities conditioned by tagetes could enhance resistance even better than tomato. Microbiota from crushed tomato-conditioned nematode communities increased resistance of the tomato holobiont, compared to microbiota of nematode communities conditioned by maize, or heat-inactivated microbiota. The 0.2 micrometre filtered microbiota from crushed nematodes had the same effect, suggesting a role of nematode-associated bacteriophages in holobiont assembly. The results indicate that soil nematodes and their associated microbiota play a role in the local organization and stabilization of plant holobionts. They can influence the resistance of plants that subsequently grow in the same soil. From an applied perspective, crop rotation schemes that alter nematode-microbiota communities could be harnessed to engineer crop holobionts.

AbstractIntegrating environmental history is essential for understanding present-day ecosystem dynamics and guiding modern conservation strategies, particularly under the EU Biodiversity Strategy for 2030. This data paper presents the nationwide digitisation and vectorisation of the French General Ordnance survey map (1818-1866), capturing the countrys forest cover at its historical minimum (a pivotal moment known as the "forest transition"). The original manuscript sheets surveyed at a 1:40,000 scale (976 sheets) were scanned, georeferenced and vectorised. They offer higher thematic accuracy than the older Cassini map and are far more feasible for nationwide vectorisation than the highly detailed Napoleonic cadastre. The area-weighted mean survey date is 1843, and the dataset covers 99.6% of modern mainland France. To correct for paper deformation, historical surveying errors and coordinate system transformations, a rigorous workflow was established. This shifted from a global 6-parameter affine transformation (root mean square error of 60 m) to a local elastic transformation based on thousands of control points, for 21% of the territory, which reduced the positioning error to 34 m. We assessed data quality by comparing the General Ordnance Survey maps with the Napoleonic cadastre--the standard reference for 19th-century land-use data--across more than 600 municipalities. The correlation between the two sources regarding forest cover percentages was exceptionally high (r>0.9). Because forests formed large, compact blocks of significant strategic interest to military engineers, they were mapped with high precision. Localised inaccuracies were primarily found in remote areas, most notably in the mountains. The resulting historical vector layer was intersected with contemporary forest data (BD Foret(R) v2, 2005-2019). Historical polygons smaller than 0.5 ha were filtered out to comply with modern FAO forest definitions. This spatial overlay generated a new dataset detailing four distinct land-use trajectories: . ancient forests (44.8% of present day forest): land classified as forest in both the 19th century and the present day (indicating maximum temporal continuity). . recent forests (55.2% of present day forest): land that was non-forested in the 19th century but has since undergone reforestation. . deforested areas (18.9% of 19th-century forest): land recorded as forest in the 19th century but subsequently converted to other land uses. . stable non-forest areas: land that has remained unforested across both periods. Our results suggest that the forest area of mainland France at its historical minimum should be revised upward to 9.9 million ha. A preliminary analysis further indicates that current spatial variation in forest cover is explained more by land-use dynamics occurring since the forest transition than by the initial extent of forest cover. These two open-access national datasets (the 19th-century forest layer and the land-use transition map) open the door to a better understanding of present-day forests : e.g. their biodiversity, soil quality, tree growth and belowground water quality. Furthermore, they provide decision-support tools for conservation planning. Key messageIn this data paper, we provide a map of 19th-century forests in France based on the digitisation of the military topographic map (1818-1866). By overlaying this historical source with the present-day forest map, we built a second map which allows the identification of ancient forests, recent forests, and deforestation. These maps offer avenues for historical ecology and the design of conservation strategies.

Exotic pests and pathogens pose a major threat to forest ecosystems. Early detection of newly introduced organisms is critical for implementing effective eradication measures before they become established. Citizen science platforms have emerged as promising sources of biodiversity data for detecting invasive pests and pathogens, yet their integration into formal biosecurity surveillance remains limited. Using France as a case study, we surveyed 101 professionals involved in forest and urban tree management and pest surveillance to assess their knowledge of regulated tree pests and pathogens and their attitudes towards online citizen science platforms for biosecurity applications. We focused on ten focal species representing different regulatory statuses under EU legislation. We assessed the knowledge professionals have of these species and their regulatory status, and explored sources of variation in their opinions regarding the use of citizen science platforms as a tool for post-border biosecurity. Experts involved in mandatory surveillance of regulated organisms (SORE experts) demonstrated consistent knowledge of quarantine pests, whereas other professionals knowledge varied by species, with greater familiarity for non-quarantine, widely distributed pests. Half of respondents used citizen science platforms, predominantly to consult species distribution rather than to contribute observations. Professionals receptivity to citizen science increased significantly when species were perceived as easy to identify, but they expressed more confidence in citizen science for monitoring established pests than for the early detection of quarantine species. The survey reveals that while citizen science platforms are known and valued as information sources, they remain underutilized as mechanisms for sharing field observations, even among surveillance professionals.