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The significance of sulphur (S) availability for crop yield and quality is highlighted under the global S deficiency scenario. However, little is known about the temporal trend in belowground organic S mineralisation when restoring land to productive agricultural systems, particularly for the deeper soil parts. Therefore, we investigated the decomposition of 35S-labelled methionine in surface (0-30 cm) and subsurface soil (30-60 cm and 60-90 cm) over a 48-year recultivation chronosequence (sampled after1, 8, 14, 24 and 48 years). Soil total sulphur (TS) significantly (p < 0.05) increased in surface soil but not in subsurface soils after 48 years of recultivation. Overall, the immobilisation of 35S-methionine (35S-MB) in subsurface soils relative to year 1 significantly decreased over the chronosequence but did not change in the surface samples. The 35S-MB values in subsurface soils were positively corrected with soil carbon (C) stoichiometry (Pearson correlation, p < 0.05), suggesting the immobilisation of methionine was likely constrained by microbial C demand in deep soil. Compared to year 1, 35S-SO42- released from 35S-methionine significantly declined throughout the older (≥ 8 years) soil profiles. Significant (p < 0.05) changes in the organic 35S partition (35S immobilisation and 35S released as sulphate) were observed in year 8 after the soil was recultivated with N-fixing alfalfa or fertilisers. Whereas, after that (≥ 14 years), soil organic S partition remained affected when conventional tillage and agricultural crops dominated this site. Indicating that the effect of recultivation on organic S decomposition depends on the manner of recultivation management. Our study contributes to an improved understanding of amino acid S and organic S mineralisation under severe anthropogenic disturbance.

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Microorganisms are pivotal in sustaining soil functions, yet the specific contributions of bacterial and fungal succession on the functions during vegetation restoration in metallic tailing reservoirs remains elusive. Here, we explored bacterial and fungal succession and their impacts on soil multifunctionality along a ∼50-year vegetation restoration chronosequence in China's largest vanadium titano-magnetite tailing reservoir. We found a significant increase in soil multifunctionality, an index comprising factors pertinent to soil fertility and microbially mediated nutrient cycling, along the chronosequence. Despite increasing heavy metal levels, both bacterial and fungal communities exhibited significant increase in richness and network complexity over time. However, fungi demonstrated a slower succession rate and more consistent composition than bacteria, indicating their relatively higher resilience to environmental changes. Soil multifunctionality was intimately linked to bacterial and fungal richness or complexity. Nevertheless, when scrutinizing both richness and complexity concurrently, the correlations disappeared for bacteria but remained robust for fungi. This persistence reveals the critical role of the fungal community resilience in sustaining soil multifunctionality, particularly through their stable interactions with powerful core taxa. Our findings highlight the importance of fungal succession in enhancing soil multifunctionality during vegetation restoration in metallic tailing reservoirs, and manipulating fungal community may expedite ecological recovery of areas polluted with heavy metals.

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Vegetation restoration in metallic tailing reservoirs is imperative to restore the post-mining degraded ecosystems. Extracellular enzymes determine microbial resource acquisition in soils, yet the mechanisms controlling the enzyme activity and stoichiometry during vegetation restoration in metallic tailing reservoirs remain elusive. Here, we investigated the variations and drivers of C-, N- and P-acquiring enzymes together with microbial community along a 50-year vegetation restoration chronosequence in the China's largest vanadium titano-magnetite tailing reservoir. We found a parabolic pattern in the enzyme activity and efficiency along the chronosequence, peaking at the middle restoration stage (∼30 years) with approximately six-fold increase relative to the initial 1-year site. The enzyme ratios of C:P and N:P decreased by 33 % and 68 % along the chronosequence, respectively, indicating a higher microbial demand of C and N at the early stage and a higher demand of P at the later stage. Soil nutrients directly determined the enzyme activities and stoichiometry, whereas microbial biomass and community structure regulated the temporal pattern of the enzyme efficiency. Surprisingly, increased heavy metal pollution imposed a positive effect on the enzyme efficiency indirectly by altering microbial community structure. This was evidenced by the increased microbial diversity and the conversion of copiotrophic to oligotrophic and stress-tolerant taxa along the chronosequence. Our findings provide new insights into microbial functioning in soil nutrient dynamics during vegetation restoration under increasing heavy metal pollution.

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INTRODUCTION: Gene exchange between viruses and hosts plays an important role in driving virus-host coevolution, enabling adaptation of both viruses and hosts to environmental changes. However, the mechanisms and functional significance of virus-host gene exchanges over long-term scales remain largely unexplored. OBJECTIVE: The present study aimed to gain insights into the role of viruses in virus-host interactions and coevolution by monitoring virome dynamics along a millennium-long land reclamation chronosequence. METHODS: We collected 24 soil samples from 8 stages of a millennium-long land reclamation chronosequence, including non-reclamation, and reclamation periods of 10, 50, 100, 300, 500, 700, and 1000 years. We characterized their metagenomes, and identified DNA viruses within these metagenomes. RESULTS: Our findings reveal a significant shift in viral community composition after 50 years of land reclamation, but soil viral diversity reached a stable phase approximately 300 years after the initial reclamation. Analysis of the virus-host network showed a scale-free degree distribution and a reduction in complexity over time, with generalist viruses emerging as key facilitators of horizontal gene transfer. CONCLUSION: These findings highlight the integral role of viruses, especially generalist types, in mediating gene exchanges between viruses and hosts, thereby influencing the coevolutionary dynamics in soil ecosystems over significant timescales. This study offers novel insights into long-term virus-host interactions, showing how the virome responds to environmental changes, driving shifts in various microbial functions in reclaimed land.

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Anaerobic microbial metabolisms make flooded paddy soils a major source of the greenhouse gas methane (CH4) and mobilize toxic arsenic (As), threatening rice production and consumption. Increasing temperatures due to climate change enhance these microbially mediated processes, increasing their related threats. Chronosequence studies show that long-term paddy use ("age") changes soil properties and redox biogeochemistry through soil organic carbon (SOC) accumulation, its association to amorphous iron (Fe) phases, and increased microbial activity. Using paddy and non-paddy soils from a chronosequence as proxies of soil development and incubating them at different temperatures, we show that paddy soil age influences the response of paddies to changes in temperature. Older paddies showed up to a 6-fold higher CH4 production with increasing temperature, compared to a 2-fold increase in young ones. Contrarily, changes in As mobility were higher in non-paddies and young paddies due to a lack of Fe-SOC-sorption sites. Temperature increased the formation of phytotoxic methylated As in all paddies, posing a risk for rice production. Mitigation strategies for future maintenance, abandonment, or management of paddy soils should include the consideration that history of use shapes the soils' biogeochemistry and microbiology and can influence the response of paddy soils to future temperature increases.

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The Mediterranean Basin has experienced substantial land use changes as traditional agriculture decreased and population migrated from rural to urban areas, which have resulted in a large forest cover increase. The combination of Landsat time series, providing spectral information, with lidar, offering three-dimensional insights, has emerged as a viable option for the large-scale cartography of forest structural attributes across large time spans. Here we develop and test a comprehensive framework to map forest above ground biomass, canopy cover and forest height in two regions spanning the most representative biomes in the peninsular Spain, Mediterranean (Madrid region) and temperate (Basque Country). As reference, we used lidar-based direct estimates of stand height and forest canopy cover. The reference biomass and volume were predicted from lidar metrics. Landsat time series predictors included annual temporal profiles of band reflectance and vegetation indices for the 1985-2023 period. Additional predictor variables including synthetic aperture radar, disturbance history, topography and forest type were also evaluated to optimize forest structural attributes retrieval. The estimates were independently validated at two temporal scales, i) the year of model calibration and ii) the year of the second lidar survey. The final models used as predictor variables only Landsat based metrics and topographic information, as the available SAR time-series were relatively short (1991-2011) and disturbance information did not decrease the estimation error. Model accuracies were higher in the Mediterranean forests when compared to the temperate forests (R2 = 0.6-0.8 vs. 0.4-0.5). Between the first (1985-1989) and the last (2020-2023) decades of the monitoring period the average forest cover increased from 21 ± 2% to 32 ± 1%, mean height increased from 6.6 ± 0.43 m to 7.9 ± 0.18 m and the mean biomass from 31.9 ± 3.6 t ha-1 to 50.4 ± 1 t ha-1 for the Mediterranean forests. In temperate forests, the average canopy cover increased from 55 ± 4% to 59 ± 3%, mean height increased from 15.8 ± 0.77 m to 17.3 ± 0.21m, while the growing stock volume increased from 137.8 ± 8.2 to 151.5 ± 3.8 m3 ha-1. Our results suggest that multispectral data can be successfully linked with lidar to provide continuous information on forest height, cover, and biomass trends.

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Drylands impacted by energy development often require costly reclamation activities to reconstruct damaged soils and vegetation, yet little is known about the effectiveness of reclamation practices in promoting recovery of soil quality due to a lack of long-term and cross-site studies. Here, we examined paired on-pad and adjacent undisturbed off-pad soil properties over a 22-year chronosequence of 91 reclaimed oil or gas well pads across soil and climate gradients of the Colorado Plateau in the southwestern United States. Our goals were to estimate the time required for soil properties to reach undisturbed conditions, examine the multivariate nature of soil quality following reclamation, and identify environmental factors that affect reclamation outcomes. Soil samples, collected in 2020 and 2021, were analyzed for biogeochemical pools (total nitrogen, and total organic and inorganic carbon), chemical characteristics (salinity, sodicity, pH), and texture. Predicted time to recovery across all sites was 29 years for biogeochemical soil properties, 31 years for soil chemical properties, and 6 years for soil texture. Ordination of soil properties revealed differences between on- and off-pad soils, while site aridity explained variability in on-pad recovery. The predicted time to total soil recovery (distance between on- and off-pad in ordination space) was 96 years, which was longer than any individual soil property. No site reached total recovery, indicating that individual soil properties alone may not fully indicate recovery in soil quality as soil recovery does not equal the sum of its parts. Site aridity was the largest predictor of reclamation outcomes, but the effects differed depending on soil type. Taken together, results suggest the recovery of soil quality - which reflects soil fertility, carbon sequestration potential, and other ecosystem functions - was influenced primarily by site setting, with soil type and aridity major mediators of on-pad carbon, salinity, and total soil recovery following reclamation.

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Weathering processes are recognized as drivers of soil and water resource sustainability, but how pedogenesis stage impacts contaminant reactivity and mobility in soils has been minimally investigated. The primary goal of this study was to quantify how soil development influences contaminant reactivity. To achieve this goal, soils from two depths (30 and 100 cm) across a chronosequence (ages 3.5, 20, 69, 140, 200, and 908 ky) in the Oregon Coast Range were subjected to arsenic (As) adsorption isotherms, with As removal from solution serving as a proxy for soil-contaminant reactivity. Langmuir models were applied to isotherm data to quantify relationships between contaminant retention capacity, soil age and soil physicochemical properties, and data revealed that 20 ky soils from a 30-cm-depth had the greatest affinity for As sorption (8,474.5 mg kg-1). Chemical extractions revealed that amorphous (oxy)hydroxides were the dominant mineral phases governing As sorption, even in the presence of abundant crystalline oxides. Micro-X-ray fluorescence spectroscopy revealed a strong spatial correlation between As and Fe in reacted soils. The abundance of amorphous minerals within soils is controlled by the balance between their production from weathering of primary minerals and their loss from ripening to crystalline minerals, and because the mode, extent and minerals governing contaminant sorption determine solid-aqueous phase partitioning, this knowledge will assist in improving models for predicting Critical Zone processes that govern the sustainability of soil and water quality.

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Climate and land-use changes are altering fire regimes in many regions around the world. To date, most studies have focused on the effects of altered fire regimes on woody and herbaceous communities, while the mechanisms driving post-fire bryophyte succession remain poorly understood, particularly in Mediterranean-type ecosystems. Here, we examined changes in bryophyte functional composition along a post-fire chronosequence (ranging from 1 to 20+ years) in Pyrenean oak woodlands (northeastern Portugal). To do so, we defined bryophyte functional groups based on seven morphological, reproductive, and life history traits. Then, we fitted linear and structural equation models to disentangle the direct and indirect effects of fire (time since fire and fire intensity), vegetation structure, climate, topography, and edaphic conditions on the abundance of each group. We identified two main functional groups: early colonizers (species with traits associated with strong colonization ability and desiccation tolerance) and perennial stayers (species with high competitive ability, i.e., large perennial mosses). Overall, the abundance of early colonizer species decreased with time since fire and increased with fire intensity, while the opposite was observed for perennial stayers. Thus, successional dynamics reflected a trade-off between species' competitive and colonization abilities, highlighting the role of biotic interactions later in succession. Patterns of functional composition were also consistent with changes in environmental conditions during succession, suggesting that species may experience stressful conditions (i.e., high radiation and low water availability) in early stages of post-fire succession. Our results also indicate that increased fire intensity may alter successional trajectories, leading to long-term changes in bryophyte communities. By understanding the response of bryophyte communities to fire, we were able to identify species with potential use as soil restoration materials.

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Determining how fully tropical forests regenerating on abandoned land recover characteristics of old-growth forests is increasingly important for understanding their role in conserving rare species and maintaining ecosystem services. Despite this, our understanding of forest structure and community composition recovery throughout succession is incomplete, as many tropical chronosequences do not extend beyond the first 50 years of succession. Here, we examined trajectories of forest recovery across eight 1-hectare plots in middle and later stages of forest succession (40-120 years) and five 1-hectare old-growth plots, in the Barro Colorado Nature Monument (BCNM), Panama. We first verified that forest age had a greater effect than edaphic or topographic variation on forest structure, diversity and composition and then corroborated results from smaller plots censused 20 years previously. Tree species diversity (but not species richness) and forest structure had fully recovered to old-growth levels by 40 and 90 years, respectively. However, rare species were missing, and old-growth specialists were in low abundance, in the mid- and late secondary forest plots, leading to incomplete recovery of species composition even by 120 years into succession. We also found evidence that dominance early in succession by a long-lived pioneer led to altered forest structure and delayed recovery of species diversity and composition well past a century after land abandonment. Our results illustrate the critical importance of old-growth and old secondary forests for biodiversity conservation, given that recovery of community composition may take several centuries, particularly when a long-lived pioneer dominates in early succession. Abstract in Spanish is available with online material.

Determinar en que medida los bosques tropicales que se regeneran en tierras abandonadas recuperan las características de los bosques primarios es cada vez más importante para comprender su papel en la conservación de especies raras y el mantenimiento de los servicios ecosistémicos. A pesar de ello, nuestro entendimiento sobre la recuperación de la estructura del bosque y la composición de la comunidad a lo largo de la sucesión es incompleta, ya que muchas cronosecuencias tropicales no van más allá de los primeros 50 años de sucesión. En este estudio, investigamos las trayectorias de recuperación del bosque en ocho parcelas de 1 hectárea en estadíos medios y tardíos de la sucesión forestal (40­120 años) y cinco parcelas de 1 hectárea de bosque primario, en el Monumento Natural Barro Colorado (MNBC), Panamá. En primer lugar, verificamos que la edad del bosque tenía un mayor efecto que la variación edáfica o topográfica en la estructura, diversidad y composición del bosque y luego corroboramos los resultados de parcelas más pequeñas estudiadas 20 años antes. La diversidad de especies arbóreas, pero no la riqueza de especies, y la estructura forestal se habían recuperado completamente hasta alcanzar los niveles de bosque primario a los 40 y 90 años, respectivamente. Sin embargo, los bosques secundarios carecían de especies raras y presentaban una escasa abundancia de especies especialistas del bosque antiguo, lo que condujo a una recuperación incompleta de la composición de especies, incluso a 120 años de sucesión. También encontramos pruebas de que el predominio de un pionero longevo en las primeras etapas de la sucesión provocó una alteración de la estructura forestal y retrasó la recuperación de la diversidad y composición de especies más allá de un siglo después el abandono de las tierras. Nuestros resultados ilustran la importancia crítica de los bosques primarios y secundarios más antiguos para la conservación de la biodiversidad, dado que la recuperación de la composición de la comunidad puede llevar varios siglos, especialmente cuando un pionero longevo domina en la sucesión temprana.

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Mine reclamation historically focuses on enhancing plant coverage to improve below and aboveground ecology. However, there is a great need to study the role of soil microorganisms in mine reclamation, particularly long-term studies that track the succession of microbial communities. Here, we investigate the trajectory of microbial communities of mining sites reclaimed between three and 26 years. We used high-throughput amplicon sequencing to characterize the bacterial and fungal communities. We quantified how similar the reclaimed sites were to unmined, undisturbed reference sites and explored the trajectory of microbial communities along the reclamation chronosequence. We also examined the ecological processes that shape the assembly of bacterial communities. Finally, we investigated the functional potential of the microbial communities through metagenomic sequencing. Our results reveal that the reclamation age significantly impacted the community compositions of bacterial and fungal communities. As the reclamation age increases, bacterial and fungal communities become similar to the unmined, undisturbed reference site, suggesting a favorable succession in microbial communities. The bacterial community assembly was also significantly impacted by reclamation age and was primarily driven by stochastic processes, indicating a lesser influence of environmental properties on the bacterial community. Furthermore, our read-based metagenomic analysis showed that the microbial communities' functional potential increasingly became similar to the reference sites. Additionally, we found that the plant richness increased with the reclamation age. Overall, our study shows that both above- and belowground ecological properties of reclaimed mine sites trend towards undisturbed sites with increasing reclamation age. Further, it demonstrates the importance of microbial genomics in tracking the trajectory of ecosystem reclamation.

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The allocation dynamics of soil carbon pools during soil development and land use are the key to revealing the carbon cycle process. To clarify the distribution of the soil carbon pool and its change trend, a soil reclamation chronosequence (0 a, 60 a, 160 a, 280 a, 1 000 a, and 1 500 a reclamation) was established in a typical alluvial plain in the Lower Yangtze River, and the content and density of soil organic carbon (SOC), soil inorganic carbon (SIC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC), along with carbon sequestration potential (CSP) indicators of topsoil under different land use types were measured and analyzed. The results showed that after approximately 1 500 a reclamation, the SOC content developed from the Yangtze River alluvial deposits generally increased by 4.9% after the initial decline, whereas the SIC content decreased to 0.2% from 25.8% of the total carbon content due to its rapid leaching. The MAOC content was normally higher than that of POC, and MAOC was contributing 48.0%-79.7% of the SOC accumulation. In this region, the soil organic carbon density (SOCD) accounted for 57.4%-100% of the total carbon density, the soil carbon sequestration levels (CSL) ranged from 18.6% to 56.1%, and CSP under paddy-dryland rotation increased by 20.8% compared to that under dryland. The C/N ratio and total nitrogen content are key factors in explaining soil carbon accumulation processes, and the reclamation year plays an important role in evaluating soil carbon sequestration levels. After long-term utilization, the cultivated soil in the Yangtze River floodplain must be carefully managed through balanced fertilization to maintain soil productivity, promote the accumulation of SOC, and avoid the decline in soil carbon sequestration capacity.

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Understanding compositional changes during secondary forest recovery is crucial for effective restoration efforts. While previous research has predominantly focused on shifts in species composition at the stand scale, this study delves into the recovery dynamics in three compositional aspects of location (neighbor distances), size (tree diameters), and species (tree species) at both stand and neighborhood scale. The investigation spans nine chronosequence plots within a tropical lowland rainforest ecosystem after shifting cultivation, including three each for young-secondary forests (18-30 years), old-secondary forests (60 years), and old-growth forests (without obvious human interference). The quantification of location, size, and species composition involved categorized neighbor distances (Near, Moderate, Far-distance), tree diameters (Small, Medium, Large-tree), and tree species (Pioneer, Intermediate, Climax-species) into three groups, respectively. Compositional changes at the stand scale (plot) were directly based on these groups, while at the neighborhood scale, assessment involved combination types of these groups within a neighborhood (comprising three adjacent trees). At the stand scale, neighbor distances shifted from Near to Moderate and Far, tree diameters transitioned from Small to Medium and Large, and tree species of Pioneer gave way to Climax. Meanwhile, at the neighborhood scale, there was a notable decline in the aggregations of Near-distance (N), Small-tree (S), and Pioneer-species (P), while the mixtures of Far and Moderate-distance (F-M), Large and Small-tree (L-S), and Climax and Intermediate-species (C-I) experienced a marked increase. The compositional change exhibited a recovery pattern, with the fastest recovery in neighbor distances, followed by tree diameters and tree species. Moreover, compositional recovery in tree diameters and tree species at the neighborhood scale generally lagged behind that at the stand scale. The study suggests that rapid restoration of secondary forest can be achieved by different targeted cutting according to the recovery stages, aimed at reduce the Pioneer-species, Small-tree and Near-distance in neighborhood. Our findings underscore that analyzing the compositional changes in three aspects at two scales not only provides a profound understanding of secondary forest recovery dynamics, but also offers valuable insights for guiding practices in the restoration of degraded forest ecosystems.

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Deforestation of tropical rainforests is a major land use change that alters terrestrial biogeochemical cycling at local to global scales. Deforestation and subsequent reforestation are likely to impact soil phosphorus (P) cycling, which in P-limited ecosystems such as the Amazon basin has implications for long-term productivity. We used a 100-year replicated observational chronosequence of primary forest conversion to pasture, as well as a 13-year-old secondary forest, to test land use change and duration effects on soil P dynamics in the Amazon basin. By combining sequential extraction and P K-edge X-ray absorption near edge structure (XANES) spectroscopy with soil phosphatase activity assays, we assessed pools and process rates of P cycling in surface soils (0-10 cm depth). Deforestation caused increases in total P (135-398 mg kg-1 ), total organic P (Po ) (19-168 mg kg-1 ), and total inorganic P (Pi ) (30-113 mg kg-1 ) fractions in surface soils with pasture age, with concomitant increases in Pi fractions corroborated by sequential fractionation and XANES spectroscopy. Soil non-labile Po (10-148 mg kg-1 ) increased disproportionately compared to labile Po (from 4-5 to 7-13 mg kg-1 ). Soil phosphomonoesterase and phosphodiesterase binding affinity (Km ) decreased while the specificity constant (Ka ) increased by 83%-159% in 39-100y pastures. Soil P pools and process rates reverted to magnitudes similar to primary forests within 13 years of pasture abandonment. However, the relatively short but representative pre-abandonment pasture duration of our secondary forest may not have entailed significant deforestation effects on soil P cycling, highlighting the need to consider both pasture duration and reforestation age in evaluations of Amazon land use legacies. Although the space-for-time substitution design can entail variation in the initial soil P pools due to atmospheric P deposition, soil properties, and/or primary forest growth, the trend of P pools and process rates with pasture age still provides valuable insights.

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Understanding the regeneration and succession of belowground communities, particularly in forests, is vital for maintaining ecosystem health. Despite its importance, there is limited knowledge regarding how fungal communities change over time during ecosystem development, especially under different forest restoration strategies. In this study, we focused on two restoration methods used in northern Japan: monoculture planting and natural regeneration. We examined the responses of the fungal community to monoculture plantations (active tree planting) and naturally regenerated (passive regeneration) forests over a 50-year chronosequence, using natural forests as a reference. Based on DNA metabarcoding, we assessed the richness of fungal Operational Taxonomic Units (OTUs) and their dissimilarity. Our findings revealed that soil fungal richness remained stable after natural regeneration but declined in monoculture plantations, from 354 to 247 OTUs. While the compositional dissimilarity of fungal assemblages between monoculture plantations and natural forests remained consistent regardless of the time since tree planting, it significantly decreased after natural regeneration, suggesting recovery to a state close to the reference level. Notably, the composition of key functional fungal groups-saprotrophic and ectomycorrhizal- has increasingly mirrored that of natural forests over time following passive natural regeneration. In summary, our study suggests that monoculture plantations may not be effective for long-term ecosystem function and service recovery because of their limited support for soil fungal diversity. These results underscore the importance of natural regeneration in forest restoration and management strategies.

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Glaciers retreating due to global warming create important new habitats, particularly suitable for studying ecosystem development where nitrogen is a limiting factor. Nitrogen availability mainly results from microbial decomposition and transformation processes, including nitrification. AOA and AOB perform the first and rate-limiting step of nitrification. Investigating the abundance and diversity of AOA and AOB is essential for understanding early ecosystem development. The dynamics of AOA and AOB community structure along a soil chronosequence in Tianshan No. 1 Glacier foreland were analyzed using qPCR and clone library methods. The results consistently showed low quantities of both AOA and AOB throughout the chronosequence. Initially, the copy numbers of AOB were higher than those of AOA, but they decreased in later stages. The AOB community was dominated by "Nitrosospira cluster ME", while the AOA community was dominated by "the soil and sediment 1". Both communities were potentially connected to supra- and subglacial microbial communities during early stages. Correlation analysis revealed a significant positive correlation between the ratios of AOA and AOB with soil ammonium and total nitrogen levels. These results suggest that variations in abundance and diversity of AOA and AOB along the chronosequences were influenced by ammonium availability during glacier retreat.

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Coastal soil microbiomes play a key role in coastal ecosystem functioning and are intensely threatened by land reclamation. However, the impacts of coastal reclamation on soil microbial communities, particularly on their assembly processes, co-occurrence patterns, and the multiple soil functions they support, remain poorly understood. This impedes our capability to comprehensively evaluate the impacts of coastal reclamation on soil microbiomes and to restore coastal ecosystem functions degraded by reclamation. Here, we investigated the temporal dynamics of bacterial and fungal communities, community assembly processes, co-occurrence patterns, and ecosystem multifunctionality along a 53-year chronosequence of paddy soil following reclamation from tidal flats. Reclamation of tidal flats to paddy soils resulted in decreased ß-diversity, increased homogeneous selection, and decreased network complexity and robustness of both bacterial and fungal communities, but caused contrasting α-diversity response patterns of them. Reclamation of tidal flats to paddy soils also decreased the multifunctionality of coastal ecosystems, which was largely associated with the fungal network complexity and α-diversity. Collectively, this work demonstrates that coastal reclamation strongly reshaped the soil microbiomes at the level of assembly mechanisms, interaction patterns, and functionality level, and highlights that soil fungal community complexity should be considered as a key factor in restoring coastal ecosystem functions deteriorated by land reclamation.

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BACKGROUND: Soil microbiomes are increasingly acknowledged to affect plant functioning. Research in molecular model species Arabidopsis thaliana has given detailed insights of such plant-microbiome interactions. However, the circumstances under which natural A. thaliana plants have been studied so far might represent only a subset of A. thaliana's full ecological context and potential biotic diversity of its root-associated microbiome. RESULTS: We collected A. thaliana root-associated soils from a secondary succession gradient covering 40 years of land abandonment. All field sites were situated on the same parent soil material and in the same climatic region. By sequencing the bacterial and fungal communities and soil abiotic analysis we discovered differences in both the biotic and abiotic composition of the root-associated soil of A. thaliana and these differences are in accordance with the successional class of the field sites. As the studied sites all have been under (former) agricultural use, and a climatic cline is absent, we were able to reveal a more complete variety of ecological contexts A. thaliana can appear and sustain in. CONCLUSIONS: Our findings lead to the conclusion that although A. thaliana is considered a pioneer plant species and previously almost exclusively studied in early succession and disturbed sites, plants can successfully establish in soils which have experienced years of ecological development. Thereby, A. thaliana can be exposed to a much wider variation in soil ecological context than is currently presumed. This knowledge opens up new opportunities to enhance our understanding of causal plant-microbiome interactions as A. thaliana cannot only grow in contrasting soil biotic and abiotic conditions along a latitudinal gradient, but also when those conditions vary along a secondary succession gradient. Future research could give insights in important plant factors to grow in more ecologically complex later-secondary succession soils, which is an impending direction of our current agricultural systems.

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Vegetation holds the key to many properties that make natural mires unique, such as surface microtopography, high biodiversity values, effective carbon sequestration and regulation of water and nutrient fluxes across the landscape. Despite this, landscape controls behind mire vegetation patterns have previously been poorly described at large spatial scales, which limits the understanding of basic drivers underpinning mire ecosystem services. We studied catchment controls on mire nutrient regimes and vegetation patterns using a geographically constrained natural mire chronosequence along the isostatically rising coastline in Northern Sweden. By comparing mires of different ages, we can partition vegetation patterns caused by long-term mire succession (<5000 years) and present-day vegetation responses to catchment eco-hydrological settings. We used the remote sensing based normalized difference vegetation index (NDVI) to describe mire vegetation and combined peat physicochemical measures with catchment properties to identify the most important factors that determine mire NDVI. We found strong evidence that mire NDVI depends on nutrient inputs from the catchment area or underlying mineral soil, especially concerning phosphorus and potassium concentrations. Steep mire and catchment slopes, dry conditions and large catchment areas relative to mire areas were associated with higher NDVI. We also found long-term successional patterns, with lower NDVI in older mires. Importantly, the NDVI should be used to describe mire vegetation patterns in open mires if the focus is on surface vegetation, since the canopy cover in tree-covered mires completely dominated the NDVI signal. With our study approach, we can quantitatively describe the connection between landscape properties and mire nutrient regime. Our results confirm that mire vegetation responds to the upslope catchment area, but importantly, also suggest that mire and catchment aging can override the role of catchment influence. This effect was clear across mires of all ages, but was strongest in younger mires.

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The establishment of forest plantations is an excellent silvicultural alternative to improve atmospheric carbon (C) sequestration for climate change mitigation. In recent years, the importance of forest growth and C dynamics at different stand ages have drawn huge attention for investigation. To evaluate the impacts of different stand ages on the C storage capacity of Castanopsis hystrix plantations ecosystems, we measured biomass and C content in trees, understory, litter, and soil components from field measurements at different stand ages, i.e., 6-, 10-, 15-, 25-, and 34-year-old stands. Results showed that the C stocks in trees, understory vegetation, litter, soil and the whole ecosystem increased steadily with stand age. C. hystrix C storage capacity in the 6-, 10-, 15-, 25-, and 34-year-old stands were 29.17, 56.18, 85.60, 132.19 and 157.79 Mg ha-1, respectively, while the total ecosystem C storage capacity was 68.11, 106.11, 136.13, 187.34 and 226.14 Mg ha-1, respectively. Meanwhile, the C sequestration rate in the 6-10, 10-15, 15-25 and 25-35-year-old stands were 675.28, 588.35, 465.97 and 284.39 g m2 year-1, respectively. Similarly, total biomass of trees, understory, and litter increased with stand age. Our study indicated that C. hystrix plantations are still developing in the area, since live biomass and soil C continue to accumulate despite reduced C sequestration rates. The information provided here highlight the C stock and C sequestration rates of C. hystrix at different stand ages, providing baseline information on the C dynamics of young and older stand of C. hystrix in this region; Hence, such knowledge could be useful for designing more realistic policies to mitigate climate change, such as programs to maintain continuous forest growth.

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