Mountain lakes are integrated sentinels of changes in the terrestrial environment, where these ch... more Mountain lakes are integrated sentinels of changes in the terrestrial environment, where these changes threaten the quality of the ecosystem services these lakes provide, including high biodiversity, economic and leisure activities. There are few evidentiary records of the long-term relationships between human pressure and its observed impacts. Multiproxy analyses of the Lake Bénit sediment sequence, including dating, grain-size, geochemistry, pollen, non-pollen palynomorphs and chironomid assemblage reconstructions, allowed us reconstructing past environmental evolution and lake trophic changes. Combined with the soil analyses of the catchment, these data provide a record of the relationships between human activities and the lake-catchment ecosystem, and show the effect of inundation of the shore previously used as pasture. From 2100 to 1100 yrs cal. BP, the catchment was forested. During the Middle Ages, the catchment was deforested for grazing, triggering an increase in erosion a...
Il s'agit de tirer un bilan rapide de l'operation ECEREX (Ecologie, Erosion, Experimentat... more Il s'agit de tirer un bilan rapide de l'operation ECEREX (Ecologie, Erosion, Experimentation) et de decider de la poursuite des travaux en determinant les objectifs, sous la forme, les moyens en personnel et en materiel
La distribution generale des sols sur les deux versants de la vallee de Chamonix obeit a l'et... more La distribution generale des sols sur les deux versants de la vallee de Chamonix obeit a l'etagement bioclimatique altitudinal : sols bruns ocreux a ocre podzoliques sous pessiere a l'etage montagnard, podzols et sols ocre podzoliques sous les landes subalpines a ericacees de l'etage subalpin, rankers varies sous pelouse a l'etage alpin. Cependant cet etagement masque une tres grande variete de sols a chaque etage bioclimatique, due a la diversite et a l'etagement des formations superficielles ainsi qu'a la multiplicite des microclimats. L'etude effectuee nous a permis de confirmer ou de mettre en evidence un certain nombre de mecanismes qui determinent l'etagement general des sols ainsi que la diversite des sols de chaque etage. Dans un premier temps, nous avons degage, a la suite d'une prospection approfondie des deux versants de la vallee, cinq grands facteurs du milieu, et differents degres dans l'expression de chacun de ces facteurs, qui ...
To assess the contribution of deep soil horizons to the mineral supply of trees, we investigated ... more To assess the contribution of deep soil horizons to the mineral supply of trees, we investigated the natural variation in the87 Sr/86Sr isotopic ratio of plant-available strontium with soil depth. In three sites of North-western Spain, this ratio increased with soil depth. The comparison of isotopic ratios of tree leaves and roots at different depths showed that most of the Sr accumulation in Eucalyptus globulus and Pinus pinaster growing on shallow and poor soils in this rainy climate originated from the upper soil layers. As Ca and Sr behave similarly in the soil-plant system, this conclusion can be applied to Ca. This superficial uptake is attributed to the low availability of Sr and Ca in the soil as well as to the shortness of the drought period as compared to the length of the growth period. This technique appears to offer a promising way of studying relative root distributions in soils and plant competition for nutrients.
Le present article se propose de mettre en perspective les travaux de recherche presentes dans ce... more Le present article se propose de mettre en perspective les travaux de recherche presentes dans ce volume de la Collection EDYTEM. Fruit d’une rencontre scientifique entre pedologues de l’AFES et geochimistes de FROG, ces articles nous semblent temoigner d’un renouveau des approches, des questions et des methodes d’etude sur l’evolution des sols en lien avec les activites humaines. La geochimie des sols et des sediments (en particulier la geochimie organique) nous apparait comme un outil indispensable pour reveler l’histoire des sols et des pratiques humaines a l’Anthropocene.
Knowledge & Management of Aquatic Ecosystems, 2019
This study deals with the impact of spatio-temporal heterogeneities on the assessment of lake eco... more This study deals with the impact of spatio-temporal heterogeneities on the assessment of lake ecological status according to the European water framework directive (WFD). A method, based on three-dimensional coupled hydrodynamic and ecological modeling, is presented to assess the variability of lake ecological status, and to locate the most representative sampling station of Lake Geneva (France/Switzerland). Five variables used in the lake ecological status evaluation were simulated by using the free software Delft3D. The numerical simulation results showed that the simulated ecological status based on chlorophyll a and total phosphorus concentrations measured at the regulatory monitoring station depend on the choice of the sampling date. Results also indicated a strong spatial heterogeneity in ecological status that varies from “poor” to “good” along an East-West gradient. Finally, the numerical simulation results showed that the most representative point of a mean theoretical ecol...
Mineral nutrients are a major part of all the physiological and biogeochemical processes in fores... more Mineral nutrients are a major part of all the physiological and biogeochemical processes in forest ecosystems. This is especially true for forests across Europe, which were deprived of nutrients due to intensive wood and litter use, and which experienced deposition of acids, nitrogen and sulphur over the second half of this century, resulting in significant nutrient imbalances for growth (Schulze 1989). Decreased nutrient availability can lead to a reduction of leaf size (Linder 1987), resulting in an almost instantaneous decrease in current year growth. In this way, the nutrient status of long-lived conifer needles might influence net primary production (NPP) long after a transient nutrient shortage, caused, e.g. by one dry season, has occurred. In natural forest ecosystems nutrient uptake from soil solution and nutrient release through litterfall and fine root turnover should balance each other such that the turnover time of nutrients within the system meets the requirements for stand growth (Gorham et al. 1979; Miller 1986; Attiwill and Adams 1993) and keeps the ecosystem nutrient cycle tight. Any deviation from this cycle due to anthropogenic influence (e.g. Vitousek et al. 1997) or natural disturbance (e.g. Foster et al. 1997) could alter one or more processes within the nutrient cycle with long-lasting effects on forest functioning.
Mineralisation, nitrification and denitrification are major processes in the soil nitrogen cycle ... more Mineralisation, nitrification and denitrification are major processes in the soil nitrogen cycle (see Schulze, Fig. 1.2, this Vol. Chap. 1). Nitrogen (N) mineralisation is by definition the biotic conversion of organic N into inorganic N, mainly NH4 + and NO3 −. Many organism groups, bacteria, fungi and certain soil animals, possess this capability, and the product formed is generally ammonia/ammonium, depending on the soil pH. Ammonium (NH4 +) can be oxidised via nitrite (NO2 − to nitrate (NO3 −. Both chemoautotrophic (using CO2 as a C source) and heterotrophic (using organic C as a C source) microorganisms can perform this nitrification process (Prosser 1986). Heterotrophic microorganisms can also produce nitrate directly from organic N sources (Killham 1986). Nitrate can be reduced via nitrite to nitric oxide (NO), nitrous oxide (N2O) and/or dinitrogen (N2) (denitrification). In addition to these processes, ammonium/ammonia, nitrite and nitrate can be assimilated (immobilised) by microorganisms, mycorrhizal fungi and roots. Further, ammonia and nitrite are known to react with certain organic compounds and, thus, be chemically immobilised (Nommik and Vahtras 1982; Azhar El Sayed et al. 1986).
Go to AGRIS search. Pollution Atmospherique (Jun 1993). Determination of critical loads of atmosp... more Go to AGRIS search. Pollution Atmospherique (Jun 1993). Determination of critical loads of atmospheric pollutants in natural ecosystems, particularly forests. Basic principles. The Vosges project (France ...
In order to analyse the mechanisms by which acid deposition is acting in soils, and its effects o... more In order to analyse the mechanisms by which acid deposition is acting in soils, and its effects on soil chemistry and stand nutrition, a set of field studies were initiated or extended in coniferous stands in the Vosges and the Ardennes. Sites were chosen according to several aims. First of all, because of the occurrence of forest decline, declining coniferous stands with Mg deficiencies were selected. As Mg uptake is age-dependent, we compared a young and a mature stand in the same location. We assessed the relative importance of site quality for a given deposition level by comparing rich and poor sites. Finally, the influence of deposition level was observed by using the highly polluted sites in the Ardennes as well as in Northern Bohemia as a comparison. The following results summarize the data obtained at these sites.
Medium term monitoring of forest soils in the temperate and the tropical environment allow us to ... more Medium term monitoring of forest soils in the temperate and the tropical environment allow us to show that soil solutions represent an efficient tool to assess the changes in current soil functioning because they are one of the most reactive components of the ecosystem. A conceptual model is proposed to gain insight into the interactions between soil solutions and the soil solid phase. Several examples will be presented where soil solution monitoring was used to address specific ecological questions e.g. i-the influence of stand age on element leaching, ii-the effects of tree species on current soil processes, iii-the Impact of tree species on the origin and on the dynamic of dissolved organic carbon in different soil solution types, iv-the effects of afforestation of herbaceous savannas with Eucalyptus plantations in Africa on the chemistry of superficial water, and, v the effects of fertilisation and/or liming on current soil functions.
Mountain lakes are integrated sentinels of changes in the terrestrial environment, where these ch... more Mountain lakes are integrated sentinels of changes in the terrestrial environment, where these changes threaten the quality of the ecosystem services these lakes provide, including high biodiversity, economic and leisure activities. There are few evidentiary records of the long-term relationships between human pressure and its observed impacts. Multiproxy analyses of the Lake Bénit sediment sequence, including dating, grain-size, geochemistry, pollen, non-pollen palynomorphs and chironomid assemblage reconstructions, allowed us reconstructing past environmental evolution and lake trophic changes. Combined with the soil analyses of the catchment, these data provide a record of the relationships between human activities and the lake-catchment ecosystem, and show the effect of inundation of the shore previously used as pasture. From 2100 to 1100 yrs cal. BP, the catchment was forested. During the Middle Ages, the catchment was deforested for grazing, triggering an increase in erosion a...
Il s'agit de tirer un bilan rapide de l'operation ECEREX (Ecologie, Erosion, Experimentat... more Il s'agit de tirer un bilan rapide de l'operation ECEREX (Ecologie, Erosion, Experimentation) et de decider de la poursuite des travaux en determinant les objectifs, sous la forme, les moyens en personnel et en materiel
La distribution generale des sols sur les deux versants de la vallee de Chamonix obeit a l'et... more La distribution generale des sols sur les deux versants de la vallee de Chamonix obeit a l'etagement bioclimatique altitudinal : sols bruns ocreux a ocre podzoliques sous pessiere a l'etage montagnard, podzols et sols ocre podzoliques sous les landes subalpines a ericacees de l'etage subalpin, rankers varies sous pelouse a l'etage alpin. Cependant cet etagement masque une tres grande variete de sols a chaque etage bioclimatique, due a la diversite et a l'etagement des formations superficielles ainsi qu'a la multiplicite des microclimats. L'etude effectuee nous a permis de confirmer ou de mettre en evidence un certain nombre de mecanismes qui determinent l'etagement general des sols ainsi que la diversite des sols de chaque etage. Dans un premier temps, nous avons degage, a la suite d'une prospection approfondie des deux versants de la vallee, cinq grands facteurs du milieu, et differents degres dans l'expression de chacun de ces facteurs, qui ...
To assess the contribution of deep soil horizons to the mineral supply of trees, we investigated ... more To assess the contribution of deep soil horizons to the mineral supply of trees, we investigated the natural variation in the87 Sr/86Sr isotopic ratio of plant-available strontium with soil depth. In three sites of North-western Spain, this ratio increased with soil depth. The comparison of isotopic ratios of tree leaves and roots at different depths showed that most of the Sr accumulation in Eucalyptus globulus and Pinus pinaster growing on shallow and poor soils in this rainy climate originated from the upper soil layers. As Ca and Sr behave similarly in the soil-plant system, this conclusion can be applied to Ca. This superficial uptake is attributed to the low availability of Sr and Ca in the soil as well as to the shortness of the drought period as compared to the length of the growth period. This technique appears to offer a promising way of studying relative root distributions in soils and plant competition for nutrients.
Le present article se propose de mettre en perspective les travaux de recherche presentes dans ce... more Le present article se propose de mettre en perspective les travaux de recherche presentes dans ce volume de la Collection EDYTEM. Fruit d’une rencontre scientifique entre pedologues de l’AFES et geochimistes de FROG, ces articles nous semblent temoigner d’un renouveau des approches, des questions et des methodes d’etude sur l’evolution des sols en lien avec les activites humaines. La geochimie des sols et des sediments (en particulier la geochimie organique) nous apparait comme un outil indispensable pour reveler l’histoire des sols et des pratiques humaines a l’Anthropocene.
Knowledge & Management of Aquatic Ecosystems, 2019
This study deals with the impact of spatio-temporal heterogeneities on the assessment of lake eco... more This study deals with the impact of spatio-temporal heterogeneities on the assessment of lake ecological status according to the European water framework directive (WFD). A method, based on three-dimensional coupled hydrodynamic and ecological modeling, is presented to assess the variability of lake ecological status, and to locate the most representative sampling station of Lake Geneva (France/Switzerland). Five variables used in the lake ecological status evaluation were simulated by using the free software Delft3D. The numerical simulation results showed that the simulated ecological status based on chlorophyll a and total phosphorus concentrations measured at the regulatory monitoring station depend on the choice of the sampling date. Results also indicated a strong spatial heterogeneity in ecological status that varies from “poor” to “good” along an East-West gradient. Finally, the numerical simulation results showed that the most representative point of a mean theoretical ecol...
Mineral nutrients are a major part of all the physiological and biogeochemical processes in fores... more Mineral nutrients are a major part of all the physiological and biogeochemical processes in forest ecosystems. This is especially true for forests across Europe, which were deprived of nutrients due to intensive wood and litter use, and which experienced deposition of acids, nitrogen and sulphur over the second half of this century, resulting in significant nutrient imbalances for growth (Schulze 1989). Decreased nutrient availability can lead to a reduction of leaf size (Linder 1987), resulting in an almost instantaneous decrease in current year growth. In this way, the nutrient status of long-lived conifer needles might influence net primary production (NPP) long after a transient nutrient shortage, caused, e.g. by one dry season, has occurred. In natural forest ecosystems nutrient uptake from soil solution and nutrient release through litterfall and fine root turnover should balance each other such that the turnover time of nutrients within the system meets the requirements for stand growth (Gorham et al. 1979; Miller 1986; Attiwill and Adams 1993) and keeps the ecosystem nutrient cycle tight. Any deviation from this cycle due to anthropogenic influence (e.g. Vitousek et al. 1997) or natural disturbance (e.g. Foster et al. 1997) could alter one or more processes within the nutrient cycle with long-lasting effects on forest functioning.
Mineralisation, nitrification and denitrification are major processes in the soil nitrogen cycle ... more Mineralisation, nitrification and denitrification are major processes in the soil nitrogen cycle (see Schulze, Fig. 1.2, this Vol. Chap. 1). Nitrogen (N) mineralisation is by definition the biotic conversion of organic N into inorganic N, mainly NH4 + and NO3 −. Many organism groups, bacteria, fungi and certain soil animals, possess this capability, and the product formed is generally ammonia/ammonium, depending on the soil pH. Ammonium (NH4 +) can be oxidised via nitrite (NO2 − to nitrate (NO3 −. Both chemoautotrophic (using CO2 as a C source) and heterotrophic (using organic C as a C source) microorganisms can perform this nitrification process (Prosser 1986). Heterotrophic microorganisms can also produce nitrate directly from organic N sources (Killham 1986). Nitrate can be reduced via nitrite to nitric oxide (NO), nitrous oxide (N2O) and/or dinitrogen (N2) (denitrification). In addition to these processes, ammonium/ammonia, nitrite and nitrate can be assimilated (immobilised) by microorganisms, mycorrhizal fungi and roots. Further, ammonia and nitrite are known to react with certain organic compounds and, thus, be chemically immobilised (Nommik and Vahtras 1982; Azhar El Sayed et al. 1986).
Go to AGRIS search. Pollution Atmospherique (Jun 1993). Determination of critical loads of atmosp... more Go to AGRIS search. Pollution Atmospherique (Jun 1993). Determination of critical loads of atmospheric pollutants in natural ecosystems, particularly forests. Basic principles. The Vosges project (France ...
In order to analyse the mechanisms by which acid deposition is acting in soils, and its effects o... more In order to analyse the mechanisms by which acid deposition is acting in soils, and its effects on soil chemistry and stand nutrition, a set of field studies were initiated or extended in coniferous stands in the Vosges and the Ardennes. Sites were chosen according to several aims. First of all, because of the occurrence of forest decline, declining coniferous stands with Mg deficiencies were selected. As Mg uptake is age-dependent, we compared a young and a mature stand in the same location. We assessed the relative importance of site quality for a given deposition level by comparing rich and poor sites. Finally, the influence of deposition level was observed by using the highly polluted sites in the Ardennes as well as in Northern Bohemia as a comparison. The following results summarize the data obtained at these sites.
Medium term monitoring of forest soils in the temperate and the tropical environment allow us to ... more Medium term monitoring of forest soils in the temperate and the tropical environment allow us to show that soil solutions represent an efficient tool to assess the changes in current soil functioning because they are one of the most reactive components of the ecosystem. A conceptual model is proposed to gain insight into the interactions between soil solutions and the soil solid phase. Several examples will be presented where soil solution monitoring was used to address specific ecological questions e.g. i-the influence of stand age on element leaching, ii-the effects of tree species on current soil processes, iii-the Impact of tree species on the origin and on the dynamic of dissolved organic carbon in different soil solution types, iv-the effects of afforestation of herbaceous savannas with Eucalyptus plantations in Africa on the chemistry of superficial water, and, v the effects of fertilisation and/or liming on current soil functions.
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