Sewage sludge application in forest plantations is an interesting complementary alternative practice to sewage sludge reutilization and recycling, with a significant and sustainable net effect in ...climate change mitigation. However, to optimize it a detailed knowledge of its effects on ecosystem components such as plants, soil, water and fauna is needed. We investigated the effects of sewage sludge application on soil, tree growth and floristic diversity in a ten-year-old plantation of European larch (Larix decidua Mill.). Our one-hectare study site, located at Mélisey, Haute-Saône, France (47°753′ Lat., 6°580′ Long.), was subdivided into six plots. Three plots, alternating with three control plots (no sewage sludge application), were amended in June 2008 with 0.4tDWha−1 obtained from a municipal urban wastewater treatment plant in Mélisey. Within each plot, one subplot was delimited and sludge was again manually applied at 3t of DWha−1 in July 2009 and March 2010 to the soil surface of the amended subplots without incorporation. The results showed no effect on radial and height growth of European larch amended with 0.4tDWha−1. While a significant temporary increase in pH, macro-element contents (N, P and Ca) and the trace metal (Cu and Zn) concentration in the soil was observed, it had no significant effect on needles and sporocarp contents. The number of species in the amended subplots with 3tDWha−1year−1 increased by 80% compared to the control. However, the relative species abundance present only in amended subplots remains <1, except for Hypericum humifusum.
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•The impacts of sewage sludge application in larch plantation were studied.•Lack of sewage sludge effects on soil and underwood diversity.•No significant effects on diameter and height growth of larch tree•No accumulation of Cu, Zn, Pb and Cd in larch needles and edible sporocarps•Small dose (0.4tDWha−1) explains lack of effects on analyzed parameters
Aims
Afforestation of trace-element contaminated soils, notably with fast growing trees, has been demonstrated to be an attractive option for bioremediation due to the lower costs and dispersion of ...contaminants than conventional cleanup methods. Mycorrhizal fungi form symbiotic associations with plants, contributing to their tolerance towards toxic elements and actively participating to the biorestoration processes. The aim of this study was to deepen our understanding on the effects of mycorrhizal inoculation on plant development and fungal community at two trace-element contaminated sites (Pierrelaye and Fresnes-sur-Escaut, France) planted with poplar (
Populus trichocarpa
x
Populus maximowiczii
).
Methods
The 2 sites were divided into 4 replicated field blocks with a final plant density of 2200 tree h
-1
. Half of the trees were inoculated with a commercial inoculum made of a mix of mycorrhizal species. The sites presented different physico-chemical characteristics (e.g., texture: sandy soil
versus
silty-loam soil and organic matter: 5.7%
versus
3.4% for Pierrelaye and Fresnes-sur-Escaut, respectively) and various trace element contamination levels.
Results
After 7 years of plantation, inoculation showed a significant positive effect on poplar biomass production at the two sites. Fungal composition study demonstrated a predominance of the phylum Ascomycota at both sites, with a dominance of
Geopora Arenicola
and
Mortierella elongata
, and a higher proportion of ectomycorrhizal and endophytic fungi (with the highest values observed in Fresnes-sur-Escaut: 45% and 28% for ECM and endophytic fungi, respectively), well known for their capacity to have positive effects on plant development in stressful conditions. Furthermore, Pierrelaye site showed higher frequency (%) of mycorrhizal tips for ectomycorrhizal fungi (ECM) and higher intensity (%) of mycorrhizal root cortex colonization for arbuscular mycorrhizal fungi (AMF) than Fresnes-sur-Escaut site, which translates in a higher level of diversity.
Conclusions
Finally, this study demonstrated that this biofertilization approach could be recommended as an appropriate phytomanagement strategy, due to its capacity to significantly improve poplar productivity without any perturbations in soil mycobiomes.
In many societies, livelihood strategies are based on a combination of economic strategies, including natural resources such as trees for wood, leaves, and fruits. Archeological wood charcoals are ...residues of human activity related to fire. They provide evidence of fuelwood and, in some contexts, timber, handcraft activities, and fruit production. They represent a detailed record of the way ancient woodlands were exploited. However, charcoal analyses are often confined to the study of taxa and their relative frequency, and socio-economic interpretations are thus limited. In the last two decades, dendro-anthracological studies have been developed. Tree-ring widths, radius of curvature, and carbon isotope contents are increasingly used as indicators of wood gathering practices, woodland management and climate. Nevertheless, in the absence of standards, measurement procedures and data processing are very diverse. The challenge for archeological charcoal analyses is thus to improve analytical tools, especially on dendro-anthracological and isotopic aspects, in order to improve the interpretation of archeological assemblages and advance the discipline. As an example, we present a new approach for taxa growing in Western Europe combining (i) different dendro-anthracological parameters, (ii) an anthraco-typological approach based on modern-day wood stands, (iii) identification of anatomical signatures revealing particular forestry practices, and (iv) stable carbon isotopes. This opens the discussion on methodological perspectives and the associated scientific questions focusing on woodland exploitation and climate, and on the interest of a systemic approach for the analysis of charcoal in archeological contexts.
Among the main parameters contributing to the characterization of firewood exploitation modes, the age of the collected wood is very difficult to assess in anthracology. In this paper, we propose an ...original way to investigate the age of the exploited wood, the heartwood formation process which takes place in 20–25-year-old deciduous oak trees. The formation of tyloses in earlywood vessels is an important feature of the changeover of sapwood to heartwood. However, tylosis formation also occurs in sapwood. Therefore, the observation of the mere presence of tyloses in vessels, as routinely performed in anthracology, is not sufficient to distinguish sapwood from heartwood. The aim of this study was thus to use the proportion of vessels sealed by tyloses as a discriminating marker between sapwood and heartwood applicable to anthracology in order to characterize firewood exploitation in the past. The trunks and branches of ten deciduous oak trees ranging from 15 to 60 years old were sampled in three French sites. For an application to archaeological charcoal (tyloses are preserved until 800 °C), thresholds of less than 65% for sapwood and up to 85% for heartwood appear to be significant at the population level for deciduous oak (Quercus petraea/robur) in a temperate climate. Besides the indication of the minimal age (ca. 25 years old in the case of deciduous oak), the variability of the proportion of vessels with tyloses in sapwood is explored as a good indicator of the vitality of the wood which opens new prospects for the exploitation of dendro-anthracological parameters, such as the discrimination of branch wood.
A main concern of dendroclimatic reconstruction is to distinguish in the tree ring proxy the influence of the climate variables of interest from other controlling factors. In order to investigate ...age, site and climate controls on tree ring width and cellulose δ18O, measurements have been performed in nearby groups of young (145 years old) and older (310–405 years old) oak trees in south-western France, covering the period 1860–2010.
Within a given site, inter-tree deviations are small, pointing to a common climatic signal. Despite a similar inter-annual variability, the average level of cellulose δ18O in the young tree group is ∼0.8‰ higher than in the old trees. Such offsets might be caused by different soil properties and differences in the fraction of the source water used by trees from different depths. The δ18O of water in the top soil layer is directly related to the current growing season precipitation, while deeper water can have a lower and more constant δ18O. Local cave drip waters at 10m depth indeed show a constant isotopic composition, which corresponds to pluri-annual mean precipitation.
A 2‰ increasing trend is observed in cellulose δ18O of young trees in the first 30 years of growth, during a period when no trend is visible in older trees. This increase can be quantitatively explained by humidity gradients under the forest canopy, and a changing microclimate around the crown as trees grow higher.
While relationships between tree ring width and climate appear complex, the isotopic composition of cellulose is strongly correlated with summer maximum temperature, relative humidity and evapotranspiration (r≈0.70). Weaker correlations (r≈0.40) are identified with precipitation δ18O from a 15-year long local record and from the REMOiso model output. These results imply that leaf water enrichment has a stronger control on the inter-annual variability of cellulose δ18O than the δ18O of precipitation.
This study demonstrates the suitability of oak tree ring cellulose δ18O for reconstructing past summer climate variability in south-western France, provided that the sampling and pooling strategy accounts for the fact that trees from different sites and of different age can introduce non-climatic signals.
The aim of the present study is to deepen the current understanding of the microbial communities at two poplar phytomanagement sites to reveal the environmental factors that drive the abundance, ...diversity and composition of microbial communities. A soil analysis revealed that the two soils displayed contrasting physico-chemical characteristics, with significant lower pH and higher Cd, Zn and Mn CaCl2-extractable fractions at Leforest site, compared with Pierrelaye site. The fungal and bacterial community profiles in the poplar roots and soils were assessed through Illumina MiSeq sequencing. Diversity indices and β-diversity measures illustrated that the root microbial communities were well separated from the soil microbial communities at both sites. A detailed study of the fungal composition showed that Ascomycota dominated the overall fungal communities on poplar soil, the root samples at Pierrelaye, and the unplanted soil at the experimental sites. Conversely, Basidiomycota accounted for a much higher percentage of the fungal community in poplar root samples from the Leforest site. The root bacterial communities were dominated by Alphaproteobacteria and Actinobacteria, and the soil samples were dominated by Alphaproteobacteria and Acidobacteria. The occurrence and dominance of the ectomycorrhizal community at Leforest but not at Pierrelaye is the major feature of our data set. Overall, ectomycorrhizal root symbionts appeared to be highly constrained by soil characteristics at the phytomanagement sites. Our data support the view that mycorrhizal inoculation is needed in highly stressed and nutrient-poor environments.
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•Two anthropospheric soils displayed contrasting physico-chemical characteristics.•Fungal and bacterial communities were assessed through Illumina Miseq sequencing.•Root microbial communities were well separated from soil microbial communities.•Ascomycota dominated the fungal community in unplanted soils and Pierrelaye site.•The ectomycorrhizal (mostly Basidiomycota) community dominated at Leforest.
During the Industrial Revolution and until the 19th century, the fuel used in metallurgy was charcoal. The frequent charcoal-making places identified in European archaeological sites are one of the ...only direct markers of this activity. Understanding the soil stratigraphy of these locations enables us to characterize the intensity of charcoal production and especially to grasp an insight into the forest management of the studied site during charcoal making. Two types of soil profiles have been observed in Europe. The first presents one or several sterile horizons identifiable with the naked eye, separating charcoal levels. The second, which is the most commonly observed type at European archaeological sites, is characterized by a single charcoal level of variable thickness. For the present study, located in eastern France (Franche-Comté), we propose to characterize the soil profile of a charcoal platform, which looks like the second type observed at the European scale, through the application of an innovative pair of methods: The Raman analysis and micromorphology. The Raman paleothermometer, defined by Deldicque et at. (2016) was adapted to define the temperatures reached in charcoal-making contexts. These measurements agree with the literature and experiments. These temperatures are regularly distributed over the profile, confirming the reuse of the platform. Similarly, the micromorphology of the soil profile reveals clear indicators of reuse, with no evidence of long interruptions in charcoal making.
The Franche-Comte region played an important role in the iron industry since at least the Hallstatt Period, but particularly since the industrial revolution (from the end of the 18th century). The ...presence of thousands of charcoal kilns in the main forest of Besançon (regional capital) is the subject of this study. The aim was to further our understanding of these archaeological objects, and to characterize the impact of charcoal production on the past vegetation. A geophysical survey (magnetic susceptibility) was conducted on two platforms. Charcoal analyses of 11 charcoal kilns and a regressive approach on the current vegetation were undertaken for comparative purposes. The platforms are modern and seem to have been used several times during a short 250-year period. Based on historical sources and compared with forests used for the iron industry, the vegetation of the forest of Chailluz appears to have been harvested for a variety of purposes, notably the iron industry and domestic use. Tree species used to produce charcoal were correlated with the environmental offering and site conditions but charcoal production seemed to open the forest structure. More light demanding taxa and fewer shade-tolerant species than nowadays have been observed.
Growing lignocellulosic crops on marginal lands could compose a substantial proportion of future energy resources. The potential of poplar was explored, by devising a field trial of two hectares in ...2007 in a metal-contaminated site to quantify the genotypic variation in the growth traits of 14 poplar genotypes grown in short-rotation coppice and to assess element transfer and export by individual genotypes. Our data led us to conclusions about the genotypic variations in poplar growth on a moderately contaminated site, with the Vesten genotype being the most productive. This genotype also accumulated the least amounts of trace elements, whereas the Trichobel genotype accumulated up to 170 mg Zn kg−1 DW in the branches, with large variation being exhibited among the genotypes for trace element (TE) accumulation. Soil element depletion occurred for a range of TEs, whereas the soil content of major nutrients and the pH remained unchanged or slightly increased after 10 years of poplar growth. The higher TE content of bark tissues compared with the wood and the higher proportion of bark in branches compared with the wood led us to recommend that only stem wood be harvested, instead of the whole tree, which will enable a reduction in the risks encountered with TE-enriched biomass in the valorization process.
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•We observed genotypic variations in growth of poplar at a moderately contaminated site.•There were large variations between genotypes for trace element accumulation.•Soil depletion occurred for a range of trace element after 10 years of growth.•Branches had accumulated a lot more elements than wood.•We recommend choosing stemwood-only harvesting instead of whole-tree harvesting.
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