Publications by authors named "Mathieu Jonard"

Forests are expected to be strongly affected by modifications in climate and disturbance regimes, threatening their ability to sustain the provision of essential services. Promoting drought-tolerant species or functionally diverse stands have recently emerged as management options to cope with global change. Our study aimed at evaluating the impact of contrasting stand-level management scenarios on the resilience of temperate forests in eastern North America and central-western Europe using the individual process-based model HETEROFOR.

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Process-based forest models combine biological, physical, and chemical process understanding to simulate forest dynamics as an emergent property of the system. As such, they are valuable tools to investigate the effects of climate change on forest ecosystems. Specifically, they allow testing of hypotheses regarding long-term ecosystem dynamics and provide means to assess the impacts of climate scenarios on future forest development.

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Despite being adapted to a wide range of environmental conditions, the vitality of European beech is expected to be significantly affected by the projected effects of climate change, which we attempted to assess with foliar nutrition and crown defoliation, as two different, yet interlinked vitality indicators. Based on 28 beech plots of the ICP Forests Level I network, we set out to investigate the nutritional status of beech in Croatia, the relation of its defoliation and nutrient status, and the effects of environmental factors on this relation. The results indicate a generally satisfactory nutrition of common beech in Croatia.

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The productivity of ecosystems and their capacity to support life depends on access to reactive nitrogen (N). Over the past century, humans have more than doubled the global supply of reactive N through industrial and agricultural activities. However, long-term records demonstrate that N availability is declining in many regions of the world.

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European beech ( L.) forests provide multiple essential ecosystem goods and services. The projected climatic conditions for the current century will significantly affect the vitality of European beech.

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Article Synopsis
  • This study looked at how oak and beech forests grow in different climate change situations using a special model called HETEROFOR.
  • The model was tested with data from many forest areas, showing it can predict how individual trees grow quite well.
  • The results indicated that while climate change can help forest growth in some places, like continental and mountainous areas, factors like temperature and rainfall can also hurt growth, but rising CO levels generally help trees grow more.
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Human societies depend on an Earth system that operates within a constrained range of nutrient availability, yet the recent trajectory of terrestrial nitrogen (N) availability is uncertain. Examining patterns of foliar N concentrations and isotope ratios (δN) from more than 43,000 samples acquired over 37 years, here we show that foliar N concentration declined by 9% and foliar δN declined by 0.6-1.

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Acid deposition arising from sulphur (S) and nitrogen (N) emissions from fossil fuel combustion and agriculture has contributed to the acidification of terrestrial ecosystems in many regions globally. However, in Europe and North America, S deposition has greatly decreased in recent decades due to emissions controls. In this study, we assessed the response of soil solution chemistry in mineral horizons of European forests to these changes.

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Because the capability of terrestrial ecosystems to fix carbon is constrained by nutrient availability, understanding how nutrients limit plant growth is a key contemporary question. However, what drives nutrient limitations at global scale remains to be clarified. Using global data on plant growth, plant nutritive status, and soil fertility, we investigated to which extent soil parent materials explain nutrient limitations.

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The aim of this study was to assess whether French forest soils are sources or sinks of carbon and to quantify changes in soil organic carbon (SOC) stocks over time by resampling soil in long-term forest monitoring plots. Within each plot, and for each survey, soils were sampled at five points selected in five subplots and divided into layers. Composite samples were produced for each layer and subplot, then analysed for mass, bulk density and SOC.

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The spatially explicit model of leaf litter can help to understand its dispersal process, which is very important to predict the distribution pattern of leaves on the surface of the earth. In this paper, the spatially explicit model of leaf litter was developed for 20 tree species using litter trap data from the mapped forest plot in an evergreen broad-leaved forest in Tiantong, Zhejiang Pro- vince, eastern China. Applicability of the model was analyzed.

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The response of forest ecosystems to increased atmospheric CO2 is constrained by nutrient availability. It is thus crucial to account for nutrient limitation when studying the forest response to climate change. The objectives of this study were to describe the nutritional status of the main European tree species, to identify growth-limiting nutrients and to assess changes in tree nutrition during the past two decades.

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Accurate estimates of the amounts of nutrients immobilised in the organs and tissues of different tree species are of prime importance to make appropriate tree species selection and determine the harvesting regime that will ensure forest sustainability. Sixteen sessile oaks (Quercus petraea (Matt.) Liebl.

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The effects of meteorological variables and local canopy characteristics on throughfall chemistry were investigated within a mixed oak-beech stand during the leafed and the leafless seasons. Throughfall was collected after each rain event in 12 structural units delimited by three neighbouring trees each. For each investigated ion (H+, Mg2+, Ca2+, K+, NH4+, Na+, Cl(-), NO3(-) and SO4(2-)), mixed linear models were used to analyse the effects of the rain volume (R) and of the length of the preceding dry period (ADP) on net throughfall ion fluxes and to evaluate the influence of canopy density and tree species composition on these relationships.

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The effects of meteorological variables and tree species on stemflow chemistry were investigated within a mixed oak-beech stand during the leafed and the leafless seasons. Stemflow was collected after each rain event. For each investigated ion (H(+), Mg(2+), Ca(2+), K(+), NH(4)(+), Na(+), Cl(-), NO(3)(-), SO(4)(2-)), mixed linear models were used to analyse the effects of the rain volume (R) and of the length of the preceding dry period (ADP) on net stemflow ion fluxes as well as to assess the effect of tree size on these relationships.

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In mixed-species stands, modeling leaf litter dispersal is important to predict the physical and chemical characteristics of the forest floor, which plays a major role in nutrient cycling and in plant population dynamics. In this study, a spatially explicit model of leaf litterfall was developed and compared with two other models. These three models were calibrated for a mixed forest of oak and beech using litterfall data from mapped forest plots.

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