Nutrient remobilization is a key process in nutrient conservation in plants and in nutrient cycling in ecosystems. To predict the productivity of terrestrial ecosystems, we thus need to improve our ...understanding of the factors that control remobilization. We studied the remobilization rates of several major nutrients (N, P, S, K, Ca, and Mg) in 102 forest ecosystems representing large environmental gradients at the country scale (France). Total amounts or availability of nutrients in soils were correlated with nutrient remobilization: the larger the soil nutrient pool, the lower the remobilization rate (e.g., P remobilization decreased with increasing total or extractable inorganic P in soils). Soil type and soil parent material influenced nutrient remobilization indirectly through their effect on soil nutrients. Nutrient remobilization was also affected by the quality of soil organic matter (C:N and C:P ratios) and K-Ca-Mg antagonisms. In addition to soil properties, plant-related parameters (nutrient concentrations in foliage and leaf life span) and climate variables (e.g., precipitation and actual evapotranspiration) were also correlated with nutrient remobilization. Using multivariate analysis, we found that soil nutrient richness and the life span of the leaf were generally the two most important factors controlling nutrient remobilization. As a whole, the nutrient remobilization rate is regulated by soil nutrients through negative feedback. This general ecological pattern is modulated by ecophysiological constraints of plants, mainly leaf life span or the capability of plants to move Ca through the phloem sap.
Incorporating the phosphorus (P) cycle in climate-carbon cycle models—or calibrating pedotransfer functions to predict available soil P—are important issues. To achieve them we need to improve our ...understanding of the P cycle by focusing on processes and on the factors which control P dynamics in soils. The aim of the present study was to evaluate the generality of the relationships between physical–chemical soil properties and the availability of inorganic P (i.e. the dynamics of phosphate ions at the solid-to-solution interface), and to test the predictive capacity of these relationships. We used the French permanent network of forest monitoring (102 forests with contrasting soil properties, called network dataset) and a global compilation of published data from different ecosystems (60 studies, mainly in forests, grasslands, or croplands, called compilation dataset). All studies used an isotopic dilution method to quantify the availability of inorganic P. Results showed generality of the dominant role of aluminum and iron oxides and organic carbon in controlling the dynamics of phosphate ions in acidic and non-acidic soils. Inversely, soil texture, pH and CaCO₃ generally had no or only little effect. The control of inorganic P availability by oxides and organic carbon was confirmed by the compilation dataset, even in non-forest soils. Relationships obtained with the network dataset correctly predicted available soil inorganic P, suggesting that the dynamics of phosphate ions in soils could be simulated by including the main controlling soil properties in models. Our study provides predictive tools which could be included in diagnostic systems for the long-term management of soil fertility.
Natural recovery of acidic soils following heavy traffic is assumed to take several decades. The aim of this study was to monitor the recovery of soil penetration resistance (PR) after soil ...compaction by heavy traffic at two forest sites. The sites, located in northeast France, have soils that differ slightly in pH and silt content. The impact on soil PR following heavy traffic was dependent on the soil water content (WC) at the time of measurement, and, therefore, the entire WC range and corresponding PR values were measured. For the most acidic and silty soil, no difference in PR among treatments was observed when the soils were near saturation; however, the difference in PR values was high when soils were close to wilting point. For the least acidic and silty soil, the impact of heavy traffic on PR could be detected whatever the soil moisture, with the magnitude of the effect dependent on the soil water content and depth considered. Standardized PR values with regard to WC allowed an analysis of the evolution of the effect of heavy traffic with time. Ten years after being subjected to heavy traffic, the PR values in the 0‐ to 40‐cm layer recovered to undisturbed values at the least acidic and silty site, but not WC dynamic. The most acidic and silty soil site did not show any recovery of PR or WC dynamic ten years following traffic, although liming at this site was able to increase the regeneration of PR to undisturbed levels.
•Five beech forest ecosystems were limed with carbonates 20 to 40 years ago.•Liming reduces acidity, improves soil fertility, tree nutrition and tree growth.•Biological cycling tends to maintain the ...applied elements in the soil-plant.•Liming with carbonate may cause long term nutrient imbalances in Mg and K.
Most forest ecosystems grow on acid and nutrient poor soils. In many cases, a slow degradation of forest soil chemical fertility due to increasing external pressures (decreasing atmospheric inputs, intensification of biomass harvesting and silvicultural practices) has been observed and is a growing concern in the international forest community. When the pressure endured by low fertility forest ecosystems is too intense, nutrient losses and ecosystem function losses may occur, forest decline being the ultimate stage of this process. In such cases, forest liming with a carbonate product is a solution to restore soil fertility and reduce soil acidity, globally improve the ecosystem functioning and compensate for nutrient losses caused by biomass harvest and exportation. However, the effects of liming on ecosystem processes and the biogeochemical cycling of nutrients in forest ecosystems are still unclear. We studied the dynamics of magnesium and calcium originating from the dissolution of liming products in the different compartments (organic and mineral soil layers and, aboveground biomass) of five long-term (20 to 40 years) monitoring beech (Fagus sylvatica L.) plots located in Northern France from ecosystem magnesium and calcium budgets.
Compared to the control plots, soil exchangeable pools of Mg and Ca in the 0–15 cm mineral soil layer increased during the first decade after liming but these differences rapidly decreased after 20–30 years. The effect of liming on foliar concentrations and tree growth was still observed after 40 years, most probably because the biological cycling of these elements was more dynamic in the limed plots. Liming increased the decomposition rate of the soil organic layer but the pools of Mg and Ca in this layer remained relatively stable over time, probably because Mg and Ca concentrations in foliage and litterfall increased after the liming. Liming effects varied between sites depending on the liming product and amount, and the initial chemical fertility level of the soil. Although liming operations may help improve forest soil fertility, they may also generate nutrient deficiencies and/or imbalances for nutrients that are poorly available in the soil. The planning of liming operations therefore necessitates a thorough soil chemical fertility diagnosis.
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•We chose a proxy of the preponderance of nutrients biological cycling for French forest ecosystems.•We derived a soil sensitivity indicator to harvesting residues removal based on ...soil chemical analysis.•We simplified this indicator in order to create a simple, rapid, low-cost and reasonably reliable diagnosis tool.
Forest biomass is a source of renewable energy that can contribute to meeting international targets for reducing greenhouse gas emissions. However, removing forest harvesting residues may cause important nutrient losses. Because negative effects of increased nutrient removal are not systematic, forest managers need tools for soil sensitivity assessment, to decide whether they can or not increase biomass harvesting without impairing long term forest productivity and health. This study follows two goals: (i) define forest ecosystem sensitivity indicators derived from soil physico-chemical analyses and (ii) build and test a simplified tool that predicts such soil sensitivity. After screening international literature, nutrient concentration in the topsoil was chosen as the simplest and currently most accurate indicator of soil sensitivity. With a consolidated database on French forest soils, we built diagnostic keys that predict soil sensitivity using only five parameters: humus form, topsoil texture, depth of CaCO3 apparition, ecological region, and rooting depth. We performed a statistical evaluation of the simplified tool on independent data sets and evaluated it in the field with potential users. As compared with the existing French forest soils sensitivity indicator, our diagnosis tool displayed lower high and low sensitivities classification errors and allowed to differentiate sensitivity into five elemental ones (Ca, Mg, K, P and N). All participating end users agreed with the necessity of such indicator and appreciated the simplicity of diagnosis with our tool. This study shows a complete research and development process, from the translation of scientific knowledge into an indicator of sustainable forest management to the simplification for assimilation.
Key message
Aggregation was studied in two acidic forest soils (NE France) to investigate the potential link between available Ca and Mg content and soil aggregate size distribution and properties. ...Clay content influenced the aggregation status while clay mineralogy influenced aggregate stability and dynamics. Aggregation status and reactivity of soil components contributed to the difference of exchangeable Ca and Mg content in topsoil between the two sites.
Context
Though nutrient fluxes are important to define forest soil chemical fertility, the quantification of nutrient reservoirs in the soils and their availability to tree uptake is essential. A thorough understanding of nutrient availability requires an investigation of nutrient location and distribution in the soil solid phase.
Aims
The general aim was to investigate the potential link between available Ca and Mg content and soil aggregate size distribution and their properties (chemical, physical, mineralogical).
Methods
Soil aggregates were separated according to three size classes (200–2000 μm; 50–200 μm; < 50 μm) in two forest soils of the Lorraine plateau (France), both classified as Luvisols ruptic. The physical, chemical, and mineralogical properties were measured for each aggregate class.
Results
We showed that the relative abundance of an intermediate aggregate class 200–50 μm was relevant to explain the difference of exchangeable Ca and Mg between sites. These aggregates were the poorest in organic and reactive mineral components and were unstable, which may mitigate the retention of Ca and Mg by ion-exchange.
Conclusion
This study highlights the role of aggregation and reactivity of soil components as relevant determinants of cation availability to tree uptake in soils.
Les sols forestiers sont le plus généralement pauvres et la moitié d’entre eux a une valeur de pHeau inférieure à 5 L’écosystème s’est lentement adapté à cet état de fait via le processus complexe ...des cycles biogéochimiques, où le recyclage massif des éléments utiles conduit à une frugalité apparente des peuplements forestiers et à un ensemble de fonctions très satisfaisantes, dont la production Toute réduction de fertilité dans ses composantes physique, chimique et biologique, totalement interactives, se traduit par une dégradation de ces fonctions La contrainte physique liée à la mécanisation des opérations sylvicoles présente un risque majeur quant à la durabilité des sols Les effets du tassement sont analysés dans cet article à partir des résultats obtenus dans deux sites expérimentaux installés sur les sols sensibles du plateau Lorrain, suivis pendant une douzaine d’années Les résultats montrent que si la dégradation des sols est rapide, leur restauration est lente Des travaux sur le long terme sont indispensables Quoi qu’il en soit, la protection des sols, en particulier de leur structure physique, représente un enjeu majeur.
It was time to take stock. We modified the humipedon classification key published in 2018 to make it easier and more practical. This morpho-functional taxonomy of the topsoil (humipedon) was only ...available in English; we also translated it into French and Italian. A standardized morpho-functional classification of humipedons (roughly the top 30–40 cm of soil: organic and organomineral surface horizons) would allow for a better understanding of the functioning of the soil ecosystem. This paper provides the founding principles of the classification of humipedon into humus systems and forms. With the recognition of a few diagnostic horizons, all humus systems can be determined. The humus forms that make up these humus systems are revealed by measuring the thicknesses of the diagnostic horizons. In the final part of the article, several figures represent the screenshots of a mobile phone or tablet application that allows for a fast recall of the diagnostic elements of the classification in the field. The article attempts to promote a standardized classification of humipedons for a global and shared management of soil at planet level.
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•Published data were compiled worldwide to quantify the effects of removing residues.•We found overall reductions in total and available soil nutrients.•This was due to increases in ...nutrient outputs and maybe changes in microbial activity.•Soil fertility loss has a negative effect on the growth of the subsequent forests.•We identified the causes of variability of the effects and hence mitigation measures.
Increasing attention is being paid to using modern fuelwood as a substitute for fossil energies to reduce CO2 emissions. In this context, forest biomass, particularly harvesting residues (branches), and stumps and associated coarse roots, can be used to supply fuelwood chains. However, collecting harvesting residues can affect soil properties and trees, and these effects are still not fully understood. The main objective of the present study was to compile published data worldwide and to quantify the overall effects of removing harvesting residues on nutrient outputs, chemical and biological soil fertility and tree growth, through a meta-analysis. Our study showed that, compared with conventional stem-only harvest, removing the stem plus the harvesting residues generally increases nutrient outputs thereby leading to reduced amounts of total and available nutrients in soils and soil acidification, particularly when foliage is harvested along with the branches. Losses of available nutrients in soils could also be explained by reduced microbial activity and mineralization fluxes, which in turn, may be affected by changes in organic matter quality and environmental conditions (soil compaction, temperature and moisture). Soil fertility losses were shown to have consequences for the subsequent forest ecosystem: tree growth was reduced by 3–7% in the short or medium term (up to 33years after harvest) in the most intensive harvests (e.g. when branches are exported with foliage). Combining all the results showed that, overall, whole-tree harvesting has negative impacts on soil properties and trees that may have an impact on the functioning of forest ecosystems. Practical measures that could be taken to mitigate the environmental consequences of removing harvesting residues are discussed.
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