Forest plantations cover large areas globally, but their climate benefits remain unclear, hampering projections of the future land carbon (C) sink. Here, we combined an unprecedented 14-years series of eddy-covariance CO2 fluxes (net ecosystem productivity, NEP) with biometric measurements to explore C balance in a commercial Eucalyptus plantation in Brazil across three rotations. The plantation exhibited a 14-year average and maximum annual NEP of 9.8 and 20.2 MgC ha-1 y-1, respectively, which ranks among the highest documented forest productivity. The amount of time before the forest recaptures as much C as was emitted after harvest was substantially shorter than previously published values: 20 and 27 months, for first and second harvest, respectively. Time series of leaf area index, but not trunk biomass growth, were strongly related to NEP dynamics (> 75% of explained variance at annual and monthly scales) suggesting possible amenability to remote-sensing assessment in Eucalyptus plantations. Estimates of C accumulation in litter and below-ground stocks varied from positive to negative depending on the methodology used, and showed substantial differences across rotations. This indicates that long-term C accumulation in commercial Eucalyptus plantations is not guaranteed, despite their high productivity.

Large land parcels of photovoltaic (PV) parks are expanding rapidly worldwide to support the energy transition. Their growing footprint in rural landscapes raises concerns about the impact such a development has on local micrometeorology and surface-atmosphere exchanges. Yet, the aerodynamic behavior of PV canopies compared to existing land uses remains poorly understood. This study compared wind dynamics and turbulence under near-neutral conditions above a 140-hectare PV park and a nearby homogeneous pine forest in southwestern France. Results showed that turbulence within the PV canopy was highly anisotropic and strongly dependent on wind direction. Under winds perpendicular to the panel rows, the flow displayed characteristics typical of dense or row-structured vegetative canopies, with an inflection in the mean velocity profile, strong drag, and efficient momentum transport dominated by sweep motions. Parallel winds, however, produced weaker drag and turbulence, a logarithmic mean profile, and elongated streamwise structures typical of shear flows over weakly rough surfaces. Based on these findings, we proposed a physically based parameterization of the mean wind velocity profile for PV canopies, depending on the wind direction and key structural properties of the PV array. The parameterization combined a logarithmic law with a roughness-sublayer correction above the panels and an exponential-logarithmic formulation within. This parameterization enabled the introduction of directional aerodynamic effects of PV parks into land-atmosphere models.

Trees located within the urban canopy are known to mitigate the urban heat island effect and heat waves by lowering the canopy air temperature via evapotranspiration and surface shading. They are also invoked as a nature-based solution to improve air quality through the absorption and deposition of anthropogenic pollutants. However, urban trees can have the adverse effect of reducing ventilation within the canopy as well as the dispersion of pollutants. Heat and mass exchanges between the urban canopy and the overlying atmosphere play a key role in air temperature and air quality at the pedestrian level. These exchanges are driven by turbulent motions developing at different scales, within the urban canopy, in the overlying atmospheric boundary layer, and at their interface. Quantifying the role of urban trees in these exchanges and their links to ventilation or dispersion processes within the canopy is challenging due to the complexity of urban surfaces and the various processes involved in surface-atmosphere interactions.The CITRY field campaign was carried out to characterize turbulent exchanges of momentum, heat, and mass as well as fine particles concentrations in an urban environment from canopy to boundary-layer scales, under various stability conditions and seasonal tree characteristics, specifically the presence of leaves. The experimental set-up was installed in a residential area of the city of Nantes (France) over a period of 10 months (March-December 2025). A wide range of instruments was deployed at different heights from the roof of a 14m-tall building and within the urban canopy. Within the urban canopy, four ultrasonic anemometers were installed on two masts, at 6 m and 10 m above ground level (a.g.l.). Two ultrasonic anemometers and one Doppler LiDAR wind profiler were positioned on the rooftop to measure wind and turbulence at 20 m and 24 m a.g.l., and between 55 m and 400 m, respectively. Within and above the canopy, gas analyzers (LI‐COR) were also installed at 10 and 24 m a.g.l., close to the ultrasonic anemometers, to deduce water vapor and carbon dioxide turbulent fluxes. Particulate matter sensors, covering particle diameters from 0.2 to 40 micrometers, were deployed across the site, on streetlight poles and on masts at several heights within and above the urban canopy, to capture the spatial variability of particle concentration.We will present a preliminary analysis of this observational dataset, including a statistical assessment of the effects of wind sector, wind speed, atmospheric stability, and leaf state on water vapor and carbon dioxide fluxes and particulate matter concentrations. Additionally, for selected periods, the main characteristics of the turbulent structures responsible for canopy–atmosphere exchanges will be shown, as well as their size dependency to the thermal stability.

The recent development of low-cost optical particle counters (OPCs) presents new opportunities for improving spatial coverage of particle concentration in the atmosphere as they are more affordable, compact, and energy efficient than traditional OPCs. In particular, these OPCs could improve our ability to quantify dust emissions in complex environments during aeolian soil erosion. The high-frequency sampling capacity (1 Hz) of some sensors may make them suitable for estimating dust emissions using the eddy-covariance method. Here, the capability of the low-cost OPC-N3 from Alphasense to estimate size-resolved dust flux using the eddy-covariance method is evaluated. During the Jordan Wind erosion And Dust Investigation (J-WADI) experiment, we tested one OPC-N3 against two traditional reference OPCs, the Promo and Fidas, from Palas GmbH. The N3 and Promo OPCs were located in close proximity to a sonic anemometer, enabling the correlation of dust concentration and vertical velocity fluctuations for estimating dust fluxes. Despite the high-temperature and dusty wind conditions of the campaign, the N3 monitored the dynamics and magnitude of dust concentration with reasonable precision. The turbulence characteristics of the dust concentration fluctuations measured by the N3, including variance, skewness, kurtosis, and energy spectrum, were similar to those from the Promo. However, the N3 flow rate exhibited variations under these outdoor conditions that affected the concentration of fine dust particles, and certain particles around 1 µm appeared to be misclassified in the upper size bin. After correcting the N3 dust concentration to address these discrepancies and after calibrating it against a reference OPC, the N3 accurately estimated the dust emission flux, with differences of less than 30 % compared to the reference OPC. Our results confirm the potential of low-cost OPCs for dust erosion research. Nonetheless, further evaluation of low-cost OPCs is still needed across different environments and weather conditions.

Intertidal mudflats, present all over the world are excluded from global carbon budget calculation; while these ecosystems are increasingly recognized to be as productive as tropical forests. With an annual global productivity estimated to be in the order of 500 million tons of carbon, mudflats can therefore represent up to 20% of the global production of the oceans, whereas they occupy only 0.03% of their surface, with a total area estimated at 130,000 km2. Despite their potentially high contribution to the overall carbon budget, their actual contribution remains unknown. Moreover, these ecosystems are currently under threat from global climate changes and increased human activities. In this context, estimating the actual carbon uptake by these ecosystems from the local to the global scale is a challenge that has to be tackled, which is the objective of this project. The main innovation of our project resides in coupling hyperspectral remote sensing, with CO2 fluxes measured at different spatial and temporal scales using benthic chambers and atmospheric eddy covariance. The first results shown the effect of seasons, tide, and habitats on CO2 fluxes, making intertidal mudflats as a sink, rather than a source of CO2. The final objective is to map the gross primary production (GPP) to estimate for the first time the contribution of these ecosystems at the global carbon cycle and more specifically, to the Blue Carbon. Such tools and results will help predicting what will happen to the tidal ecosystems due to changes linked to global climate changes and assist in developing mitigation and adaptation strategies to comply with the objectives of the Paris Agreement.

Within the coastal zone, salt marshes are atmospheric CO2 sinks and represent an essential component of biological carbon (C) stored on earth due to a strong primary production. Significant amounts of C are processed within these tidal systems which requires a better understanding of the temporal CO2 flux dynamics, the metabolic processes involved and the controlling factors. Within a temperate salt marsh (French Atlantic coast), continuous CO2 fluxes measurements were performed by the atmospheric eddy covariance technique to assess the net ecosystem exchange (NEE) at diurnal, tidal and seasonal scales as well as the associated relevant biophysical drivers. To study marsh metabolic processes, measured NEE was partitioned into gross primary production (GPP) and ecosystem respiration (Reco) during marsh emersion allowing to estimate NEE at the marsh–atmosphere interface (NEEmarsh = GPP − Reco). During the year 2020, the net C balance from measured NEE was −483 g C m−2 yr−1 while GPP and Reco absorbed and emitted 1019 and 533 g C m−2 yr−1, respectively. The highest CO2 uptake was recorded in spring during the growing season for halophyte plants in relationships with favourable environmental conditions for photosynthesis, whereas in summer, higher temperatures and lower humidity rates increased ecosystem respiration. At the diurnal scale, the salt marsh was a CO2 sink during daytime, mainly driven by light, and a CO2 source during night-time, mainly driven by temperature, irrespective of emersion or immersion periods. However, daytime immersion strongly affected NEE fluxes by reducing marsh CO2 uptake up to 90 %. During night-time immersion, marsh CO2 emissions could be completely suppressed, even causing a change in metabolic status from source to sink under certain situations, especially in winter when Reco rates were lowest. At the annual scale, tidal immersion did not significantly affect the net C uptake of the studied salt marsh since similar annual balances of measured NEE (with tidal immersion) and estimated NEEmarsh (without tidal immersion) were recorded.

A Correction to this paper has been published: https://doi.org/10.1038/s41597-021-00851-9.

Process-based vegetation models are widely used to predict local and global ecosystem dynamics and climate change impacts. Due to their complexity, they require careful parameterization and evaluation to ensure that projections are accurate and reliable. The PROFOUND Database (PROFOUND DB) provides a wide range of empirical data on European forests to calibrate and evaluate vegetation models that simulate climate impacts at the forest stand scale. A particular advantage of this database is its wide coverage of multiple data sources at different hierarchical and temporal scales, together with environmental driving data as well as the latest climate scenarios. Specifically, the PROFOUND DB provides general site descriptions, soil, climate, CO2, nitrogen deposition, tree and forest stand level, and remote sensing data for nine contrasting forest stands distributed across Europe. Moreover, for a subset of five sites, time series of carbon fluxes, atmospheric heat conduction and soil water are also available. The climate and nitrogen deposition data contain several datasets for the historic period and a wide range of future climate change scenarios following the Representative Concentration Pathways (RCP2.6, RCP4.5, RCP6.0, RCP8.5). We also provide pre-industrial climate simulations that allow for model runs aimed at disentangling the contribution of climate change to observed forest productivity changes. The PROFOUND DB is available freely as a “SQLite” relational database or “ASCII” flat file version (at https://doi.org/10.5880/PIK.2020.006/; Reyer et al., 2020). The data policies of the individual contributing datasets are provided in the metadata of each data file. The PROFOUND DB can also be accessed via the ProfoundData R package (https://CRAN.R-project.org/package=ProfoundData; Silveyra Gonzalez et al., 2020), which provides basic functions to explore, plot and extract the data for model set-up, calibration and evaluation.

We assembled homogenized long-term time series, up to 19 years, of measurements of net ecosystem exchange of CO2 (NEE) and its partitioning between gross primary production (GPP) and respiration (R-eco) for five different ecosystems representing the main plant functional types (PFTs) in France. Part of these data was analyzed to determine the influence of the main environmental variables on carbon fluxes between temperate ecosystems and the atmosphere, and to investigate the temporal patterns of their variations. A multi-temporal statistical analysis of the time series was conducted using random forest (RF) and wavelet coherence approaches. The RF analysis showed that, in all ecosystems, the incident solar radiation was highly correlated with GPP and that GPP was better correlated with the temporal variations of NEE than R-eco. The air temperature was the second most important driver in ecosystems with seasonal foliage, i.e., deciduous forest, cropland and grassland; whereas variables related to air or soil drought were prominent in evergreen forest sites. The environmental control on CO2 fluxes was tighter at high frequency suggesting an increased resilience to environmental variations at longer time spans. The spectral analysis performed on three of the five sites selected revealed contrasting temporal patterns of the cross-coherence between CO2 fluxes and climate variables among ecosystems; these were related to the respective PFT, management and soil conditions. In all PFTs, the power spectrum of GPP was well correlated with NEE and clearly different from R-eco. The spectral correlation analysis showed that the canopy phenology and disturbance regime condition the spectral correlation patterns of GPP and R-eco with the soil moisture and atmospheric vapour deficit.

The mechanistic model GO+ describes the functioning and growth of managed forests based upon biophysical and biogeochemical processes. The biophysical and biogeochemical processes included are modelled using standard formulations of radiative transfer, convective heat exchange, evapotranspiration, photosynthesis, respiration, plant phenology, growth and mortality, biomass nutrient content, and soil carbon dynamics. The forest ecosystem is modelled as three layers, namely the tree overstorey, understorey and soil. The vegetation layers include stems, branches and foliage and are partitioned dynamically between sunlit and shaded fractions. The soil carbon submodel is an adaption of the Roth-C model to simulate the impact of forest operations. The model runs at an hourly time step. It represents a forest stand covering typically 1 ha and can be straightforwardly upscaled across gridded data at regional, country or continental levels. GO+ accounts for both the immediate and long-term impacts of forest operations on energy, water and carbon exchanges within the soil–vegetation–atmosphere continuum. It includes exhaustive and versatile descriptions of management operations (soil preparation, regeneration, vegetation control, selective thinning, clear-cutting, coppicing, etc.), thus permitting the effects of a wide variety of forest management strategies to be estimated: from close to nature to intensive. This paper examines the sensitivity of the model to its main parameters and estimates how errors in parameter values are propagated into the predicted values of its main output variables.The sensitivity analysis demonstrates an interaction between the sensitivity of variables, with the climate and soil hydraulic properties being dominant under dry conditions but the leaf biochemical properties being most influential with wet soil. The sensitivity profile of the model changes from short to long timescales due to the cumulative effects of the fluxes of carbon, energy and water on the stand growth and canopy structure. Apart from a few specific cases, the model simulations are close to the values of the observations of atmospheric exchanges, tree growth, and soil carbon and water stock changes monitored over Douglas fir, European beech and pine forests of different ages. We also illustrate the capacity of the GO+ model to simulate the provision of key ecosystem services, such as the long-term storage of carbon in biomass and soil under various management and climate scenarios.

Huit ans de travaux de recherche sur les services ecosystemiques dans une grande ferme cafeiere du Costa Rica (observatoire collaboratif Coffee-Flux, en systeme agroforestier a base de cafeiers sous de grands arbres d'Erythrina poeppigiana, surface projetee de couronne de l'ordre de 16 %) ont suggere plusieurs applications pour les agriculteurs et les decideurs. Il est apparu que de nombreux services ecosystemiques dependaient des proprietes du sol (ici des Andisols), en particulier de l'erosion, de l'infiltration, de la capacite de stockage de l'eau et des elements nutritifs. Nous confirmons qu'il est essentiel de lier les services hydrologiques et de conservation au type de sol en presence. Une densite adequate d'arbres d'ombrage (plutot faible ici) permet de reduire la severite des maladies foliaires avec, en perspective, une reduction de l'usage de pesticides-fongicides. Un simple inventaire de la surface basale au collet des cafeiers permet d'estimer la biomasse souterraine et la moyenne d'âge d'une plantation de cafeiers, ce qui permet d'evaluer sa valeur marchande ou de planifier son remplacement. Le protocole de calcul actuel pour la neutralite carbone des systemes agroforestiers ne prend en compte que les arbres d'ombrage, pas la culture intercalaire. Dans la realite, si on inclut les cafeiers, on se rapproche tres probablement de la neutralite. Des evaluations plus completes, incluant les arbres, les cafeiers, la litiere, le sol et les racines dans le bilan en carbone du systeme agroforestier sont proposees. Les arbres d'ombrage offrent de nombreux servies ecosystemiques s'ils sont geres de maniere adequate dans le contexte local. Par rapport aux parcelles en plein soleil, nous montrons qu'ils reduisent l'erosion laminaire d'un facteur 2, augmentent la fixation de l'azote (N2) atmospherique et le pourcentage d'azote recycle dans le systeme, reduisant ainsi les besoins en engrais. Ils reduisent aussi la severite des maladies foliaires, augmentent la sequestration de carbone, ameliorent le microclimat et attenuent substantiellement les effets des changements climatiques. Dans notre etude de cas, aucun effet negatif sur le rendement n'a ete enregistre.

Understanding how wind and trees interact during wind storms is crucial for better predicting forest wind damage. The complexity of this interaction is enhanced by the fragmented environment of forests. Here, we present an unprecedented field experiment (TWIST) where both the wind dynamics and the tree motion in the edge region of a maritime pine forest have been recorded simultaneously during four non-destructive wind storms. For three of them, the instrumented trees were under stand flow while for one of them they were under an edge flow. Our measurements demonstrate that the well-known characteristics of stand-flow dynamics remain valid under high wind conditions. Only the sub-canopy flow appeared more intermittent as canopy-top turbulent structures penetrate easier within the canopy due to the tree foliage reconfiguration. Under similar storm intensity, the tree motions were lower under edge flow than under stand flow due to the lower turbulence of the former flow while the mean wind speed was higher. This result demonstrates the importance of considering both the turbulence and the mean wind speed in wind risk models. No impact of tree motion other than tree reconfiguration were observed on the stand flow dynamics. On the other hand, for the edge flow, our measurements reveal a peak in frequency on the wind velocity fluctuations related to the fundamental tree vibration mode. This peak was especially visible at canopy top and in the upper trunk space under high wind conditions. Compared to the stand flow, we suspect that the velocity fluctuations induced by the tree motion emerge in the edge flow due to the lower background turbulence. Our edge storm was nonetheless not strong enough for tree motion to enhance flow turbulence and for trees to enter into resonance. These findings may suggest a higher susceptibility of near-edge trees to reach resonance than stand trees due to the motion of upwind trees in a lower background turbulence.

Evapotranspiration and energy partitioning are complex to estimate because they result from the interaction of many different processes, especially in multi-species and multi-strata ecosystems. We used MAESPA model, a mechanistic, 3D model of coupled radiative transfer, photosynthesis, and balances of energy and water, to simulate the partitioning of energy and evapotranspiration in homogeneous tree plantations, as well as in heterogeneous multi-species, multi-strata agroforests with diverse spatial scales and management schemes. The MAESPA model was modified to add (1) calculation of foliage surface water evaporation at the voxel scale; (2) computation of an average within-canopy air temperature and vapour pressure; and (3) use of (1) and (2) in iterative calculations of soil and leaf temperatures to close ecosystem-level energy balances. We tested MAESPA model simulations on a simple monospecific Eucalyptus stand in Brazil, and also in two complex, heterogeneous Coffea agroforests in Costa Rica. MAESPA satisfactorily simulated the daily and seasonal dynamics of net radiation (RMSE = 29.6 and 28.4 W m(-2); R-2 = 0.99 and 0.99 for Eucalyptus and Coffea sites respectively) and its partitioning between latent-(RMSE = 68.1 and 37.2 W m(-2); R-2 = 0.87 and 0.85) and sensible-energy (RMSE = 54.6 and 45.8 W m(-2); R-2 = 0.57 and 0.88) over a one-year simulation at half-hourly time-step. After validation, we use the modified MAESPA to calculate partitioning of evapotranspiration and energy between plants and soil in the above-mentioned agro-ecosystems. In the Eucalyptus plantation, 95% of the outgoing energy was emitted as latent-heat, while the Coffea agroforestry system's partitioning between sensible and latent-heat fluxes was roughly equal. We conclude that MAESPA process-based model has an appropriate balance of detail, accuracy, and computational speed to be applicable to simple or complex forest ecosystems and at different scales for energy and evapotranspiration partitioning.

Eight years of monitoring ecophysiology and ecosystem services (ES) in a large coffee farm of Costa Rica yields a range of practical applications for the farmer and stakeholders, thanks to numerous scientific actors and disciplines contributing to our collaborative observatory (Coffee-Flux). • A lot of ecosystem services depend on the soil properties, such as runoff/infiltration, water and nutrient storage capacity. It is essential to relate hydrological and soil conservation services to the soil type, since this might have even more importance than the crop itself for ES. Regarding the use of fertilizer, we show that some soils may have a large storage capacity, allowing producing coffee at normal yields with just a reduced, or even a minimum amount of fertilizers, for instance when the economic conditions are unfavorable. Also, due to the soil variability within the farm, it is possible to adjust fertilization to micro-local conditions and reduce the total expenses and risks of leaching of N to the environment. VNIRS and MIR are promising broadband tools for screening the variability in soils. Adjusting N fertilizer to the optimum will also considerably reduce the N2O emissions and improve the GHG balance of the farm. • Pesticides-fongicides: we show that an adequate amount of shade trees allows reducing the severity of the whole complex of leaf diseases. This also should reduce expenses and impacts on the ecosystem. • Roots: a simple survey of basal area at collar allows estimating the belowground biomass and the average age of a plantation, to judge of its market value and to decide when to replace it. • Also starch plays a key role in the trophic equilibrium between the perennial parts of the coffee plant (aerial stump, belowground stump, coarse roots) and its ephemeral parts (resprout, leaves, fruits, fine roots). Coffee plants accumulate starch in the stumps by the end of the life of their resprout, as a strategy for survival. Breeding plants with less starch build-up capacity would probably allow increasing the fraction of productive years during the lifespan of the resprouts. • Coffee farms are probably much closer to C neutrality than currently admitted using the C-Neutrality protocol. We stress the prevailing role of coffee plants + litter + soil in the ecosystem C balance. If those are excluded from the calculations as done so far, coffee farms are GHG sources, by definition. We argue that either full assessments (as proposed here, at the ecosystem level, including trees, coffee, litter, soil and roots) or consensus on “sequestration factors” (the counterpart of emission factors) would allow performing a more realistic assessment of the GHG balance. • Finally, we bring new data confirming that shade trees offer numerous ecosystem services, when adequately managed for the local context. As compared to full sun conditions, they may (i) reduce laminar erosion by a factor of ca. 2, (ii) increase the atmospheric N2 fixation and the % of N recycled into the system, thus reducing the fertilizer requirements, (iii) reduce the severity of the leaf disease complex, (iv) increase C sequestration, (v) improve the microclimate, and (vi) be a large part of the solution to face climate changes. All this is possibly without negative effects on profitability or yield, if managed properly. In our particular case-study, we encount. (Resume d'auteur)

Coffee-flux is a platform where collaborative research on coffee agroforestry is promoted: data are being shared between collaborators and positive interactions are enhanced. The philosophy is to concentrate several investigations on one specific site and for several years, to share a useful common experimental database, to develop modelling and to publish results in highly-ranked scientific journals. Applied research is also highly encouraged (e.g. C-Neutral certification, NAMA, Agronomy, etc.). Coffee-Flux benefits from infrastructure, easy access from CATIE and very good security, ready to welcome complementary scientific investigations and collaborations. The project is wide open to complementary projects, scientists and of course to students. The core data base is for sharing. The aim of Coffee-Flux is to assess carbon, nutrients, water and sediment Ecosystem Services (ES) at the scale of a coffee agroforestry watershed. Observation, experimentation, modelling and remote-sensing are combined, collecting data and calibrating models locally, then upscaling to larger regions. The project has been running continuously since 2009, in order to encompass seasonal and inter-annual fluctuations of coffee productivity and ecosystem services.

Atmospheric aerosols play a central role in both air quality and climate change. However, the evaluation of aerosol radiative forcing is still one of the greatest uncertainties in predicting future climate (IPCC, 2013). It is therefore crucial to better assess aerosol sources and related processes. At a global scale, New Particle Formation (NPF) is one of the most important aerosol sources, which could represent half of the Cloud Condensation Nuclei (CCN) rate (Merikanto et al., 2009). Several studies have observed NPF, over rural as well as urban areas, mostly during daytime, related to photochemical processes (Kulmala et al., 2004). But, only a few studies have reported nocturnal NPF (Lee et al., 2008). The origin of these nocturnal events remains sparse, mostly due to the lack of investigations. In addition, the role of biogenic volatile organic compounds (BVOCs) in NPF is still not clearly understood, even if recent advances (Riccobono et al., 2014) were proposed. Hence, new studies about NPF and their link with BVOCs are of great interest, especially in locations still poorly investigated. The Landes forest, located in southwestern France, is one of the largest monospecific forest in Europe (~1 million ha) and composed of 95% of maritime pines (pinus pinaster), a large monoterpene emitter, mainly αand βpinene, two well-known SOA precursors. Flat, with few anthropogenic inputs, under the direct influence of the Atlantic Ocean with strong photochemical periods, this forest may be considered as an “open-air laboratory”. Hence, the Landes forest appears to be one of the best suitable ecosystem to investigate NPF related to BVOCs emissions. This work is a part of the LANDEX coordinated project, aiming to assess the formation and fate of Secondary Organic Aerosols (SOA) generated from the French Landes forest. To achieve this goal, two preliminary field campaigns have been conducted in summer 2014 and 2015, in order to explore SOA related photochemistry and NPF in this forest. During both campaigns, BVOCs and their corresponding oxidation products were measured in the gas phase using online GC-FID and PTR-TOF-MS. Ozone, nitrogen oxides (NOx) and sulfur dioxide were also monitored. Aerosol size distribution and concentration were measured with a SMPS, whereas quartz fiber filter daily collected particles for off-line chemical analysis. Local meteorology (T, P, RH, solar radiations, wind speed and direction) were characterized, and completed by air mass backward trajectory calculations. The physiologic state of the ecosystem has been evaluated through latent and sensible heat fluxes and CO2 flux measurements. Ozone deposition was also measured, including its potential reactivity with very reactive BVOCs. During both preliminary campaigns, night-time NPF have been observed at high frequency rates. Through this presentation, we will focus on the 2015 field campaign, which took place during a strong hydric stress period. This period presented the highest NPF frequency rate (56%) with extremely high monoterpene concentrations. Gas phase oxidation products such as nopinone and pinonaldehyde have been successfully identified thanks to the PTR-TOF-MS. In-canopy monoterpene reactivity with ozone will be discussed in light to nocturnal NPF observation, to assess its potential contribution. Finally, the effect of hydric stress on nocturnal NPF, in the context of global warming, will be evaluated.