{"type": "FeatureCollection", "features": [{"id": "38747209", "type": "Feature", "geometry": null, "properties": {"updated": "2026-09-20T16:23:02Z", "type": "Journal Article", "created": "2024-05-15", "title": "Global evidence for joint effects of multiple natural and anthropogenic drivers on soil nitrogen cycling", "description": "Abstract

Global soil nitrogen (N) cycling remains poorly understood due to its complex driving mechanisms. Here, we present a comprehensive analysis of global soil \uffce\uffb415N, a stable isotopic signature indicative of the N input\uffe2\uff80\uff93output balance, using a machine\uffe2\uff80\uff90learning approach on 10,676 observations from 2670 sites. Our findings reveal prevalent joint effects of climatic conditions, plant N\uffe2\uff80\uff90use strategies, soil properties, and other natural and anthropogenic forcings on global soil \uffce\uffb415N. The joint effects of multiple drivers govern the latitudinal distribution of soil \uffce\uffb415N, with more rapid N cycling at lower latitudes than at higher latitudes. In contrast to previous climate\uffe2\uff80\uff90focused models, our data\uffe2\uff80\uff90driven model more accurately simulates spatial changes in global soil \uffce\uffb415N, highlighting the need to consider the joint effects of multiple drivers to estimate the Earth's N budget. These insights contribute to the reconciliation of discordances among empirical, theoretical, and modeling studies on soil N cycling, as well as sustainable N management.Understanding microbial adaptation is crucial for predicting how soil carbon dynamics and global biogeochemical cycles will respond to climate change. This study employs the DEMENT model of microbial decomposition, along with empirical mutation and dispersal rates, to explore the roles of mutation and dispersal in the adaptation of soil microbial populations to shifts in litter chemistry, changes that are anticipated with climate\uffe2\uff80\uff90driven vegetation dynamics. Following a change in litter chemistry, mutation generally allows for a higher rate of litter decomposition than dispersal, especially when dispersal predominantly introduces genotypes already present in the population. These findings challenge the common idea that mutation rates are too low to affect ecosystem processes on ecological timescales. These results demonstrate that evolutionary processes, such as mutation, can help maintain ecosystem functioning as the climate changes.Microbial carbon use efficiency (CUE) affects the fate and storage of carbon in terrestrial ecosystems, but its global importance remains uncertain. Accurately modeling and predicting CUE on a global scale is challenging due to inconsistencies in measurement techniques and the complex interactions of climatic, edaphic, and biological factors across scales. The link between microbial CUE and soil organic carbon relies on the stabilization of microbial necromass within soil aggregates or its association with minerals, necessitating an integration of microbial and stabilization processes in modeling approaches. In this perspective, we propose a comprehensive framework that integrates diverse data sources, ranging from genomic information to traditional soil carbon assessments, to refine carbon cycle models by incorporating variations in CUE, thereby enhancing our understanding of the microbial contribution to carbon cycling.Increasing soil organic carbon (SOC) stocks is a promising way to mitigate the increase in atmospheric CO2 concentration. Based on a simple ratio between CO2 anthropogenic emissions and SOC stocks worldwide, it has been suggested that a 0.4% (4 per 1000) yearly increase in SOC stocks could compensate for current anthropogenic CO2 emissions. Here, we used a reverse RothC modelling approach to estimate the amount of C inputs to soils required to sustain current SOC stocks and to increase them by 4\uffe2\uff80\uffb0 per year over a period of 30\uffc2\uffa0years. We assessed the feasibility of this aspirational target first by comparing the required C input with net primary productivity (NPP) flowing to the soil, and second by considering the SOC saturation concept. Calculations were performed for mainland France, at a 1\uffc2\uffa0km grid cell resolution. Results showed that a 30%\uffe2\uff80\uff9340% increase in C inputs to soil would be needed to obtain a 4\uffe2\uff80\uffb0 increase per year over a 30\uffe2\uff80\uff90year period. 88.4% of cropland areas were considered unsaturated in terms of mineral\uffe2\uff80\uff90associated SOC, but characterized by a below target C balance, that is, less NPP available than required to reach the 4\uffe2\uff80\uffb0 aspirational target. Conversely, 90.4% of unimproved grasslands were characterized by an above target C balance, that is, enough NPP to reach the 4\uffe2\uff80\uffb0 objective, but 59.1% were also saturated. The situation of improved grasslands and forests was more evenly distributed among the four categories (saturated vs. unsaturated and above vs below target C balance). Future data from soil monitoring networks should enable to validate these results. Overall, our results suggest that, for mainland France, priorities should be (1) to increase NPP returns in cropland soils that are unsaturated and have a below target carbon balance and (2) to preserve SOC stocks in other land uses.