Claude Nys

Forest liming durably impact the communities of ectomycorrhizas and fungal epigeous fruiting bodies

Abstract• Liming is a forestry practice used to counteract forest decline in acidic soils. It consists of direct Ca and Mg input to forest soil, which restores tree mineral nutrition, but also modifies microbial communities in soil. The aim of this study was to assess the effects of liming on both belowground (ectomycorrhizal root tips) and aboveground (epigeous sporocarps) fungal communities.• Results showed that the modification of soil chemical properties (pH, and Ca-Mg contents versus total free Al and Fe concentrations) was a stronger factor of ECM community structuring than tree host. The species appearing in limed plots were ubiquist or known as good competitors and replaced acidophilic and stress species.• At the sporocarp level, tree host was a stronger factor of community structuring than soil chemical properties associated with liming. On the whole, there was a shift in the community composition from a typical acidophilic forest fungal community of medium altitude in the untreated plots to a less typical one, with the reduced dominance of acidophilic fungi while many late-stage forest species appeared.• We finally suggest a marker species (Russula ochroleuca) to assess both above and belowground effects of liming on ectomycorrhizal communities.Résumé• Le chaulage est une pratique forestière utilisée pour restaurer la nutrition minérale des arbres apparaissant sur sol acide. Il consiste en un apport direct de Ca et Mg au sol forestier, ce qui restaure la nutrition minérale de l’arbre, mais aussi modifie les communautés microbiennes du sol. Cette étude évalue les effets du chaulage sur les communautés fongiques hypogées (apex ectomycorrhiziens : «ECM») et épigées (carpophores).• Les résultats montrent que la modification des des propriétés chimiques du sol (pH et concentrations en Ca-Mg échangeables versus concentrations en Al et Fe échangeables) est un facteur de structuration de la communauté d’ECMs plus fort que l’arbre hôte. Les espèces qui sont apparues dans les placeaux chaulés sont ubiquistes ou compétitrices et ont remplacé des espèces acidophiles ou connues pour être associées à des conditions de stress.• Concernant les carpophores, l’arbre hôte est un facteur de structuration de la communauté plus fort que les propriétés chimiques du sol associées au chaulage. Dans l’ensemble, on a observé une modification de la communauté fongique, passant d’une communauté typique de forêt acide de moyenne altitude dans les placeaux témoins vers une autre moins spécifique, caractérisée par une moindre dominance d’espèces acidophiles et l’apparition de nombreuses espèces de forêt mature.• Nous suggérons enfin une espèce marqueur (Russula ochroleuca) qui permet d’évaluer facilement les effets du chaulage sur les communautés de champignons mycorrhiziens, aussi bien du point de vue des apex mycorrhiziens que des carpophores.

Influence of Tree Roots on Nitrogen Mineralization

This study compared the total carbon (C), mineral nitrogen (N) contents and N mineralization potentials of the rhizospheric and bulk soils, collected at two depths in three forest sites in France. The site at Breuil is a comparative plantation of different species with or without fertilization, the Fougeres site is a time sequence of four Fagus sylvatica L . stands including a limed plot, and the Aubure site is a comparison between adjacent young and old Picea abies. (L.) Karst stands with different nitrifying activity. Mineral N was extracted from fresh soil with K 2 SO 4 and after laboratory incubation at 15°;C for 2 days or 1 week. The moisture, C and N contents of the rhizospheric soil were higher than in the bulk soil in the A 1 horizon, but only slightly higher or similar in A 1 B horizons. Soil-extractable NH 4 and net mineralization were much larger in the rhizospheric soil than in the bulk soil. Soil-extractable NO 3 and net nitrification were not significantly different. Soil-extractable NH 4 an...

Earthworm communities of limed coniferous soils: Field observations and implications for forest management.

A field experiment and two soil faunal surveys were carried out to determine the effect of liming on earthworm populations of European forests. In the UK, a mixed species assemblage of earthworms was introduced into a deep peat soil under a young stand of Picea sitchensis, following addition of lime. Dendrodrilus rubidus was the only introduced species to be recovered after nearly a year. Total earthworm numbers and biomass were 70% and 15% of those introduced; this included species which had not been inoculated. Earthworms were found only where the soil had been limed; most individuals were found where earthworms and lime had been applied. In a survey of long-established limed plots of Picea abies on an acid, brown earth soil in northern France, liming increased earthworm density (5 to 11 individuals m−2, compared with 6 m−2 in a nearby deciduous woodland, and 0 m−2 in unlimed P. abies plots). Similarly, in Northern Ireland, the addition of lime permitted a substantial community of earthworms to develop in deep peat soil under P. sitchensis (79 individuals m−2, compared with 5 m−2 in unlimed soils), including acid intolerant species rare in coniferous soils. Different species assemblages were found in the four different limed plots sampled. The trees growing on limed soil at this site showed greater height growth than the trees in the unlimed plots, and it is suggested that earthworms have a beneficial effect in limed coniferous soils by increasing nutrient turnover.

Spatial variability of nutrient stocks in the humus and soils of a forest massif (Fougères, France)

In this study, the spatial distribution of nutrient stocks (K, Ca, Mg and P) was examined in humus and soils at the forest massif scale (Fougères forest, France). A random stratified sampling plan including 100 sampling points was used and three potential variation factors of nutrient stocks were tested: age of stand, type of stand (broad-leaved or coniferous trees) and type of soil. Sampling classes were then compared and the variation factors were examined. Results demonstrated that nutrient stocks in the humus were not influenced by the cited factors and only the type of soil influenced nutrient stocks in soils. In fact, stocks of exchangeable elements in soils were much higher in Colluviosols-Fluviosols which show redoximorphic characteristics, and available phosphorus stocks were lower than in Alocrisols-Neoluvisols. Moreover, a low variability of nutrient stocks was observed in Alocrisols-Neoluvisols as opposed to Colluviosols-Fluviosols, which may suggest the existence of other variation factors not taken into account in this study (hydromorphic gradient, type and age of stand in hydromorphic zones).RésuméDans ce travail, la distribution spatiale des réserves de nutriments (K, Ca et Mg et P) dans les sols et les humus a été étudiée à l’échelle d’un massif forestier (Forêt de Fougères, France). Un plan d’échantillonnage aléatoire stratifié regroupant 100 sites a été utilisé et trois facteurs potentiels de variation des stocks de nutriments ont été testés : âge et type de peuplements (feuillus et résineux) et type de sol. Les classes d’échantillonnage ont ensuite été comparées et les facteurs de variation des stocks examinés. Les résultats montrent que les réserves de nutriments dans les humus ne sont pas influencées par les facteurs cités précédemment alors que seul le type de sol influence les réserves dans les sols. Les stocks de nutriments échangeables dans les sols sont en effet significativement plus élevés et les stocks de phosphore assimilable plus faibles dans les Colluviosols-Fluviosols à caractère hydromorphe en comparaison des Alocrisols-Néoluvisols. De plus, la variabilité des stocks pour les Alocrisols-Néoluvisols est faible en comparaison des Colluviosols-Fluviosols, ce qui suggère l’existence d’autres facteurs de variation non pris en compte lors de l’étude (gradient d’hydromorphie, type et âge des peuplements dans les zones hydromorphes).

2 Atmospheric Deposition in France and Possible Relation with Forest Decline

With the exception of a few pioneering studies such as the work of Albert Levy (1877-1907, in Ulrich and Williot 1993) at the turn of the last century, precipitation chemistry monitoring in rural areas really began in France at the end of the 1970s (BAPMON and EMEP networks), as a result of international studies showing the negative impact of precipitation acidity on surface waters and the possibilities of long-range pollution transport (Gorham and Gordon 1960; Zephoris et al. 1984). No dense deposition network covering the whole country was organized until the end of the 1980s, but a large number of local studies were initiated, the results of which were often never published.

The effects of liming and gypsum applications on a sessile oak (Quercus petraea (M.) Liebl.) stand at La Croix-Scaille (French Ardennes) I. Site characteristics, soil chemistry and aerial biomass

In a former 45 to 50 year old sessile oak ( Quercus petraea (M.) Liebl.) coppice mixed with birch (Betula pubescens Ehrh.) and rowan (Sorbus aucuparia L.) on a poor acidic forest soil at la Croix-Scaille in the French Ardennes, several liming amendments were applied in 1990 and 1994. Data on soil and soil solution composition, as well as stand growth and foliar composition were collected between 1994 and 1997. All treatments, containing 1.4 t ha-1 equivalent of CaO supplied as lime, gypsum or a mixture of the two, resulted in an increase of cation exchange capacity and base saturation down to 15 cm and for CaSO4 treatments down to 30 to 45 cm, increases of soil pH and Ca concentration at the surface and a decrease of Al concentration in the soil and soil solution in the surface layers. No negative effects like increased nitrate or cation leaching were observed. Although Mg nutrition was not improved by the treatments (not containing Mg), a relative and maintained gain of radial increment of sessile oak in the order of 40% for both lime and gypsum applied, was observed immediately from the first year on, after the application (1991).

Influence of waterlogging on carbon stock variability at hillslope scale in a beech forest (Fougères forest — West France)

The Kyoto protocol [39] directs the signatory countries including France to establish an inventory of carbon stocks in forests. Precise estimates of carbon stocks are hampered by local spatial variability, in particular in wetland areas [25]. The aims of this work are: (i) to estimate the spatial variability of carbon stocks on two hillslopes presenting respectively, a transition between a well-drained zone and a wetland area over a short-distance, and a very progressive transition; (ii) to correlate this variability with soil waterlogging and topographic variations and (iii) to evaluate carbon stock prediction by modelling waterlogging intensity as soil organic carbon (SOC) stocks increase significantly with waterlogging. However, SOC stocks in redoximorphic soils are highly variable, particularly in zones where carbon is redistributed due to erosion and sedimentation. In the litter and the vegetation, the age and density of the stand are the main explanatory factors of C variability. Topographic modelling of the waterlogging intensity could improve the spatial estimation of SOC stocks but not of the C stocks in the humus and vegetation.RésuméInfluence de l’hydromorphie sur la variabilité des stocks de carbone à l’échelle de versants dans une hêtraie de plaine (forêt de Fougères, Bretagne). Le protocole de Kyoto [39] a amené les pays signataires dont la France à établir un inventaire précis des stocks de carbone dans les forêts. Cependant, la variabilité spatiale observée dans les zones hydromorphes limite la précision de l’évaluation [25]. Les objectifs de ce travail ont été de : (i) décrire la variabilité spatiale des stocks de carbone à l’échelle de deux versants en forêt de Fougères présentant respectivement une transition rapide et une transition progressive entre une zone bien drainée et une zone hydromorphe; (ii) relier cette variabilité à des facteurs explicatifs potentiels (hydromorphie des sols, topographie) et (iii) de déterminer l’apport d’une modélisation topographique de l’hydromorphie sur la prédiction des stocks de carbone. L’effet de l’hydromorphie se traduit par une augmentation significative des stocks de carbone dans les sols. Cependant, les stocks de carbone des sols hydromorphes sont caractérisés par une forte variabilité, en particulier en zones fortement soumises à l’érosion et à la sédimentation. Dans la végétation et les humus, l’âge et la densité du peuplement sont les facteurs influençant le plus la variabilité des stocks. Ainsi, la modélisation topographique de l’intensité de l’hydromorphie permet d’améliorer la précision des estimations des stocks de carbone dans les sols, mais n’a pas d’intérêt pour prédire les stocks des autres compartiments.

Fertilization of Declining Conifers in the Vosges and the Ardennes: Effects on Soil, Nutrient Cycling, and Tree Health, Growth and Physiology

Long before the beginning of the DEFORPA Programme in 1984, Vosgian soils were known to be very poor in Ca, and some stands were found to be Mg deficient as early as 1972 (Vallee 1967; Jover and Barneoud 1978). In the early 1980s, German researchers had drawn attention to Ca and Mg deficiencies in the Black Forest (under similar geological conditions as in the Vosges) (Zottl and Mies 1983) and Bavaria (Zech and Popp 1983). There was also speculation that acidity had increased over recent decades under the influence of acid deposition. It therefore seemed logical to investigate the effect of Ca and Mg fertilization in the earliest stages of the DEFORPA Programme.

Ion dynamics in acid forest soils as affected by addition of Ca fertilizers

Ca fertilizers may be used as tools to improve the chemical status of acidic, base poor forest soils. The downward movement of ions after addition of CaCO3, CaCO3 + MgO, and CaS04 · 2H2O was studied by monitoring the leachate composition from three types of columns — A1/B, mull/A1/B and moder/A1/B — reconstructed from an acid brown forest soil profile. The fertilizers were surface-applied at rates of 0, 0.56, 2.80 and 5.60 t ha−1 equivalent CaO, and the treated columns were leached with local rainfall in an open-air nursery during a 20-month period. For all column types and rates of application, the leaching of Ca increased in the order: control < CaCO3 + MgO < CaCO3 < CaSO4 · 2H2O. Retention of solubilized Ca from gypsum was mainly achieved by simple exchange with resident cations, with no major pH change relative to the control. The elution of Ca and desorbed cations with predominantly SO42− anions resulted in an important increase in total cationic mobilization compared to the control. Due to kinetic restraints and strong buffering by the soil, the downward movement of Ca (from CaCO3) and Mg (from MgO) ions was greatly limited. The mobility of Mg ions from CaCO3 + MgO was however much greater than that of Ca, despite considerably larger inputs of the latter. In the leachates from the columns without humus, total Al concentrations decreased exponentially with increase in pH. For the other column types the reduced Al leaching, when observed, was not associated to any major pH increase. Gypsum application depressed nitrification but increased DOC leaching relative to the control. Liming generally had no or little influence on either NO3− or DOC leaching, but increased SO42− mobilization in some cases. Total cation leaching from the non gypsum-treated columns was chiefly affected by NO3− dynamics. Varying the rate of fertilizer application did not modify the mechanisms involved in the downward movement of the various fertilizers, but could influence the intensity of the processes as well as the rate of soil chemical evolution.

Magnesium Isotope Variations to Trace Liming Input to Terrestrial Ecosystems: A Case Study in the Vosges Mountains.

Liming with Ca and Mg carbonates is commonly used to reduce soil and stream acidity and to improve vegetation growth and nutrition in forests. Ten years ago, dolomite lime was experimentally applied to a forest catchment on granite in the Vosges Mountains (northeast France), which is characterized by acid soils and drained by an acid stream. The average Mg isotope composition of the dolomite lime (-1.75‰) was low compared with that of tree foliage (-0.70‰), granite and deep soil layers (-0.40‰), and stream water (-0.80‰) in the control catchment. After liming, the exchangeable Mg concentrations in surface soil layers, which were initially very low, increased, and the Mg isotope composition decreased (up to -0.60‰). The decrease was smaller in deeper layers but not in proportion to the increase in exchangeable Mg content, suggesting contributions from mineralization of organic matter and/or displacement of exchangeable Mg from surface layers. Before application, Mg concentration in beech and fir leaves was low, and that of 1-yr-old fir needles was lower than that in current needles. Internal Mg translocation within fir needles also resulted in a lower δMg of older needles. Three years after dolomite application, the Mg isotope composition of plant leaves was lower than that in the control catchment; this decrease (up to -1.00‰) was attributed to direct uptake of Mg from dissolving dolomite. Liming doubled the concentration of Mg in the stream, whereas the Mg isotope composition decreased correspondingly from -0.80 to -1.20‰, indicating a fast transfer of dolomite Mg to the stream. Our findings indicate that monitoring of δMg may be a promising tool to study the fate of dolomitic inputs in terrestrial and aquatic ecosystems.