bluuebunny/crossref_metadata_2025 huggingface dataset:
Net Ecosystem Productivity of a mature temperate deciduous oak forest: reconciling fluxand biometric estimates
Authors: Berveiller Daniel , Morfin Alexandre , Vincent Gaëlle , Barthes Laure , Bazot Stéphane , Guillot Timothé , Soudani Kamel , François Christophe , Delpierre Nicolas
Published: March 2024

The eddy covariance (EC) technique measures the turbulent exchanges of gasses between atarget ecosystem and the atmosphere. Provided conditions for the applicability of the ECtechnique are met (i.e. turbulent enough atmosphere, flat terrain etc.), the time integration ofturbulent exchanges of CO2 estimates the net ecosystem productivity (NEP, in terms of carbon,neglecting small losses of CH4, VOC and DOC). Since its inception, questions have emergedregarding the ability of EC to measure NEP, and independent measurements of NEP throughbiometric methods have frequently shown discrepancies between estimates. Here we compareNEP estimates of a mature, 150-yr old temperate oak forest (Fontainebleau-Barbeau, ICOS FRFon),established over the past 19 years. The NEP_EC of this 150-yr old forest is of 504 +/- 72 gCm-2 yr-1, which places it in the high range of data for mature temperate deciduous forests.Measurements of soil respiration and below-canopy EC fluxes suggest that respiration fluxes areunderestimated at FR-Fon, probably in relation to its location at the edge of a plateauoverlooking a river 50-m below. However the integration of NEP_EC over time compares well tothe one obtained from biometric estimates (combination of wood increment, litterfall, rootproductivity and variations of the soil carbon stocks), yielding 562 gC m-2 yr-1. Interestingly,we estimate that 80% of NEP was stored as an increment of the standing wood biomass, while20% ended in the accretion of the soil organic carbon stock, yielding a 10 per mil increase of theSOC stock per year, coherent with trends reported for forest soils in France, Germany andFinland.
Constraints on the mantle lithology of enriched components: evidence from E-MORB of Southwest Indian Ridge
Authors: Li Jie , Chen Ling , Dong Yan-Hui
Published: March 2024

Mid-oceanic ridge basalts (MORBs) are frequently grouped as depleted (D-MORBs), normal (N-MORBs), or enriched (E-MORBs) based on the abundances of highly incompatible elements. E-MORBs, characterized by enriched in incompatible elements, were first noted near mantle plumes, so that enrichment of highly incompatible elements was initially understood as a result of infiltration of plume-related melts into the MORB plumbing system. But for E-MORBs far from plumes, it is still controversial of the lithology of enriched components of these E-MORBs. Two major explanations are proposed that the enriched components are generated by the melting of entrained recycled crust (pyroxenite) beneath ridges or by the melting of refertilized peridotites from subducted slabs. The reason for this problem is that melting of the ambient refractory peridotite along with the enriched component will dilute the signals recorded in MORB. Therefore, the in-situ analyses of minerals and/or melt inclusions will shed new light on this question.Here high-precision in-situ analyses were conducted on olivine and plagioclase in the studied samples. According to the major and minor element contents of olivine phenocrysts, we found they have similar Ni, Mn and Ni/(Mg/Fe) contents with those from N-MORB at a given Fo, indicating a peridotitic source. Furthermore, in-situ Sr isotope in plagioclase phenocrysts and in-situ Pb isotope of plagioclase-hosted melt inclusions are also reported to constrain origin of parental magma. The isotopic results show that unlike the uniform whole-rock 87Sr/ 86Sr and 206Pb/204Pb ratios, the plagioclase phenocrysts record highly Sr and Pb isotopic heterogeneity. Strontium isotopic heterogeneity is observed between crystals even in a single thin section. Based on the high An contents of plagioclase phenocrysts and chemical disequilibrium between plagioclase phenocrysts and groundmass, we propose they crystallized early in the magma chamber and were most likely formed in different batches of mantle-derived melts. The enrichment of LREE and negative correlations between La/Sm and Pb isotopes melt inclusions, suggest that ancient continent lithosphere materials are likely present in the sub-ridge mantle of the east of the Melville FZ, SWIR. Collectively, we proposed that the continent lithosphere materials were slabbed into the upper mantle under MOR as refertilized peridotites.
Linking ecological processes and spatial patterns: the promise of remote sensing in treeline ecology
Authors: Garbarino Matteo , Morresi Donato , Weisberg Peter , Anselmetto Nicolò
Published: March 2024

Treelines are ecotones with a strong spatial nature. Remote sensing (RS) tools provide spatially explicit wall-to-wall maps in time. Nevertheless, despite the potential of RS to inform treeline ecologists on spatial patterns and underlying processes, its application is still scarce and heterogeneous. We performed a systematic review and meta-analysis of published literature with the aim to provide a question-oriented discussion of RS in treeline ecology. The main focus of the review was the role of RS as a tool for measuring spatial patterns and dynamics of treeline globally. We assessed the geographic distribution, scale of analysis, and relationships between RS techniques and ecological metrics through cooccurrence mapping and multivariate statistics. Only 10% of treeline studies applied RS. We observed four main types of applications; long-term aerial, long-term oblique, satellite timeseries, and high-resolution mapping. Long-term research and monitoring adopted coarser spatial resolution over long temporal extent, either with oblique or aerial photographs to measure treeline position and shift. Shorter temporal extents (i.e., up to 40 years) were investigated through satellite time-series, especially when dealing with coarse dynamics such as changes in climate. High-resolution imagery derived from UAV recently emerged as promising tools to measure tree height, canopy cover, and spatial patterns at a very fine spatial resolution (i.e., centimetres to metres). A multiscale and multi-sensor spatial approach was implemented in just 19% of papers. We advocate for an increasing interaction between classic treeline ecology based on field surveys and RS techniques. Also, the multi-dimensional structural complexity of treeline ecotones calls for a multiscale and multi-sensor approach, with high-resolution and low cost UAV acting as a powerful tool to fill the gap between local-scale ecological patterns and coarse-resolution satellite sensors.
The Chon Aike magmatic province: an active margin origin?
Authors: Bastias-Silva Joaquin , Spikings Richard , Riley Teal , Sanhueza Jorge
Published: March 2024

A combination of the geochemical and isotopic compositions of the Jurassic igneous rocks exposed along the Antarctic Peninsula and Patagonia suggest that they may have formed in a continental arc setting without a significant input of a mantle plume, as presented in Bastias et al. (2021). This interpretation revises previous interpretations (e.g. Pankhurst et al., 2000; Riley et al., 2001) that suggested the early deposits of the Chon Aike magmatic province in eastern and central Patagonia formed by the coupled action of an active margin and the peripheral thermal effect of the Karoo mantle plume. We present a tectono-magmatic evolution for the Chon Aike magmatic province following the argument of Bastias et al. (2021). Furthermore, we argue that a supra-subduction zone origin is supported by: (i) enriched LILE and LREE, with negative Nb, Ta, Sr and Ti anomalies in all of the Jurassic igneous rocks, which are typical of slab-dehydration reactions and thus active margins, (ii) the trace element compositions of Jurassic igneous rocks in Patagonia and the Antarctic Peninsula are indistinguishable throughout the region, and thus it is likely that they evolved via the same magmatic processes, (iii) the whole rock Nd and Sr, and zircon Hf isotopic compositions of Late Triassic-Jurassic igneous rocks show that the magmas formed from mixed sources that resided within the continental crust and (iv) numerical modelling. Therefore, unlike the igneous units of the Karoo and Ferrar LIPs, the involvement of a mantle plume is not necessary to generate any of the chronological, geochemical or isotopic characteristics of the Chon Aike magmatic province. This contribution serves as further information on the debate searching for the responsible mechanism generating the Chon Aike magmatic province: active margin vs. mantle plume.
Temporal variability of the stability field of methane hydrates in the oceans
Authors: Riccucci Leonardo , Camerlenghi Angelo , Salon Stefano , Tinivella Umberta
Published: March 2024

Climate change is mainly monitored at the Earth's surface. However, it is well known that as partof ongoing climate change, ocean circulation is also changing, and therefore the ocean floor isalso subject to temperature changes.In this study, the depth of the global methane hydrate stability zone was assessed by analyzing itschanges over the period from 1993 to 2018 to investigate the effect of climate change on thestability of methane hydrates.Indeed, seafloor sediments are often permeated by a methane hydrate phase, the stability ofwhich depends on the pressure and temperature field, among other parameters, and any changesin temperature conditions near the seafloor can bring the methane hydrate into unstableconditions.The data needed for the assessment of methane hydrate stability were obtained from The GlobalOcean Physics Reanalysis data set (GLORYS12V1), produced under the European CopernicusMarine Environment Monitoring Service (CMEMS), and GEBCO- The General Bathymetric Chartof the Oceans. The data were then processed with original data processing software developed inFortran and Python languages.A quantitative estimate of the amount of methane released into ocean masses by the dissociationof methane hydrate in shallow sediments over the period under consideration was also obtained.The release of large amounts of methane could have an impact on submarine geological hazards,such as submarine landslides, and the eventual reaching of the atmosphere by methane wouldreinforce ongoing climate change.
Using Paleoclimate modeling to analyse the precipitations and temperatures during the Holocene over the Arabian Peninsula
Authors: Alsarraf Hussain
Published: March 2024

The aim of this study is to analyze the past climate over the Arabian Peninsula and the changes which will influence the future climate change. This study will focus on the Holocene climate over the Arabian Peninsula, that began 11,700 years ago. In this study the ensemble simulations of the LOVECLIM coupled model is used considering that the model proven to be the best concurrence with the reconstructions. LOVECLIM 1.2 model includes the atmosphere component is ECBilt2, the ocean and see ice component is CLIO3, the continental biosphere component land surface VECODE, the oceanic carbon cycle component LOCH, and the polar ice sheet component AGISM. LOVECLIM 1.2 simulate the present climate conditions and the last 20 millennia, the Last Glacial Maximum and the Holocene climate. The model used to simulate temperatures and precipitations in the Last Glacial Maximum and the Holocene climate over the Arabian Peninsula. The model outcomes indicate that high amount of precipitation occurred over the central region of  the Arabian Peninsula during the mid Holocene. The fluctuation of the Indian monsoon and the shift of the intertropical convergence zone (ITCZ) plays huge part on participation over the Arabian Peninsula.
Investigating the influence of temperature on respiration rates of the benthic foraminifer Nonionella sp. T
Authors: Palme Tina , Heinz Petra , Polovodova Asteman Irina , Nagy Matthias
Published: March 2024

With the warmest year on record and heating of oceans all over the world, it is of increasing interest how marine organisms adapt to these changing conditions. Benthic foraminifera are important components of marine ecosystems, contributing to biogeochemical cycling and serving as indicators of environmental change. Gaining knowledge of their role in energy and nutrient flows leads to a better understanding of ecosystem functioning. In this study we investigated oxygen respiration rates of the potentially invasive benthic foraminifer Nonionella sp. T1 originating from sediments within the Gullmar Fjord and cultivated in artificial sea water (ASW) in the laboratory at the University of Vienna. Nonionella sp. T1 was incubated at two different temperatures: 12 °C closely resembling natural fjord conditions and 20 °C simulating thermal stress to the foraminifers. Additionally, the influence of light on this species’ oxygen consumption was tested because it is known to harbour kleptoplasts (= functioning chloroplasts from algal food source), but little information exists about kleptoplast potential photosynthetic activity. Prior to the experiment, foraminifers were fed with the living diatom Phaeodactylum tricornutum, which is also used as food source for the culture. A non-invasive method was used to analyze oxygen respiration rates. The method involved placing an Oxygen Sensor Spot in a small, 2.5 ml airtight glass vial filled with ASW alongside the foraminifera. Oxygen concentrations under dark and light conditions and at 12 °C and 20 °C, respectively, were documented using an Oxygen Microsensor. We used a large number (n = 100, triplicates) of cleaned, living specimens. Respiration rates are given in µmol O2/h calculated for biovolume (µm³) which was assessed for each individual using photo microscopy. The measured oxygen respiration rates under dark conditions at 12 °C fall within the upper range of previously observed foraminiferal respiration rates. Lower respiration rates during light exposure indicate oxygen production which is likely related to the activity of kleptoplasts. The pending results of the experiment at 20 °C will show if respiratory activity of Nonionella sp. T1 will increase with temperature and if the efficiency of oxygen production of their kleptoplasts is temperature-dependent.
Stormwater trees in urban runoff management: Water balance of the SenseCity Experimental Device 
Authors: Zime Yerima Hayath , Seidl Martin , Gromaire Marie-Christine , Bensaoud Abdelkader , Berthier Emmanuel
Published: March 2024

Faced with high levels of soil sealing combined with the effects of climate change, stormwater trees offer an adaptive solution for stormwater management. A stormwater tree is a street tree that has been designed to manage runoff from the adjacent pavement, while enhancing its development and various ecosystem services. It's a natured based solution for sustainable source control of runoff that's developing more and more, but whose operation is not yet completely mastered. The aim of the present study is to analyze and better understand the hydrologic functioning of such a device for a better application in the city, based on an experimental prototype, implemented in SenseCity, in Paris conurbation. SenseCity is a mini-city made up of a roadway and walls simulating a Canyon Street, with ball maples (Acer platanoide Globosum) planted on either side, one side of which is fed by runoff from 88m2 of pavement - these are the stormwater trees. The three stormwater trees are planted in a 1.6m-diameter reservoir with two main substrate layers, the first consisting of 20cm of Rainclean, a depollution filter providing temporary storage before infiltration into the deeper 60cm layer of topsoil. The runoff infiltrates through these two layers before reaching the clayey natural underground, where it can be exfiltrated to the soil and excess water can be collected in an underdrain. Various sensors were installed to study this system. These include inflow (Krohne Optiflux electromagnetic flowmeter), soil water content (Campbell SoilVue TDR probe), sap flow (Edaphic Implexx sensor) which allows to assess the evapotranspiration flux from the trees, outflow from the underdrain (Précis Mécanique 2x1-liter auger) and meteorological parameters. Most parameters are measured at 15-minute time steps.The results obtained over one year (April 2022-March 2023) show exfiltration and transpiration rates on the system to represent respectively 53% and 27% of the inflow. Annual drainage accounts for around 19%. Exfiltration and transpiration are the main means of reducing runoff volumes. These different processes are not evenly distributed over the months. Transpiration rates are highest in summer, helping to cool the urban microclimate, while drainage and exfiltration is highest in winter. In summer, for example, transpiration rates were 41% and drainage 11%, while in winter transpiration was reduced to 5% and drainage increased to 32%.
Pyrite oxidation rates and timing of weathering in supergene deposits: new insights from XPS approach
Authors: Poot Julien , Felten Alexandre , Colaux Julien L. , Gouttebaron Rachel , Lepêcheur Guillaume , Rochez Gaëtan , Yans Johan
Published: March 2024

Pyrite is one of the most common sulfides on Earth and occurs in many Cu, Pb and Zn sulfides (hypogene) ore deposits. By using XPS (X-ray Photoelectron Spectroscopy) surface and depth analyses, we propose a new experimental approach to determine the oxidation rate of pyrite in three exposure/conditions: i) air, ii) water and iii) water drip (Figure 1). Pyrite samples are almost pure and were collected from the Danube–Bouchon quarry (Hautrage, Belgium), in Barremian black clays of the Wealden facies sediments in the Mons Basin. These pyrites are nodules with cubic aggregates on the surface which were used for the different experiments.The results reveal a maximum oxidation rate of 11.7 ± 1.8 nm day−1 for drip exposure associated with the precipitation of Fe-sulfates or/and oxides depending on the experimental conditions. These data can be extrapolated to the different zones of weathering profiles (gossan, saprolite and cementation zone). The extrapolation shows a maximum rate of 4.3 ± 0.6 m Ma−1, values consistent with those obtained by other methods such as isotope dating of weathering profiles (e.g. [1,2]). The oxidation in natural systems can vary following different factors, such as the nature of the host rock (protore) and the primary mineralogy, the porosity/permeability and fractures, the presence of an oxidizing environment, climate change over time, the action of bacteria as catalysts, …Figure 1 - Macroscopic evolution of pyrite oxidation over time in the different experiments [3] References[1] De Putter T, Ruffet G, Yans J, Mees F (2015) Ore Geol Rev 71:350–362. https://doi.org/10.1016/J.OREGEOREV.2015.06.015[2] Vasconcelos PM, Conroy M (2003) Geochim Cosmochim Acta 67:2913–2930. https://doi.org/10.1016/S0016-7037(02)01372-8.[3] Poot J, Felten A, Colaux JL, Gouttebaron R, Lepêcheur G, Rochez G, Yans J (2024) Environ Earth Sci 83:9. https://doi.org/10.1007/s12665-023-11325-z
Understanding the dynamics of multi-sector impacts of hydro-meteorological extremes: a methods overview
Authors: Madruga de Brito Mariana , Sodoge Jan , Fekete Alexander , Hagenlocher Michael , Koks Elco , Kuhlicke Christian , Messori Gabriele , de Ruiter Marleen , Schweizer Pia-Johanna , Ward Philip J.
Published: March 2024

Hydro-meteorological extremes, such as droughts and floods, often trigger a series of compound and cascading impacts due to interdependencies between coupled natural and social systems. However, studies typically only consider one impact and disaster event at a time, ignoring causal chains, feedback loops, and conditional dependencies between impacts. Analyses capturing these complex patterns across space and time are thus needed to inform effective adaptation planning. Here, we present a collection of methods that can be used for assessing the dynamics of the multi-sector compound and cascading impacts (CCI) of hydro-meteorological extremes. We discuss existing challenges, good practices, and potential ways forward. Rather than pursuing a single methodological approach, we advocate for methodological pluralism. We see complementary or even convergent roles for analyses based on quantitative (e.g. data-mining, systems modeling) and qualitative methods (e.g. mental models, qualitative storylines). The data-driven and knowledge-driven methods provided here can serve as a useful starting point for understanding the dynamics of both high-frequency CCI and low-likelihood but high-impact CCI.
Why it's time to switch your EO data processing and analysis to the cloud 
Authors: Ray William
Published: March 2024

Traditionally, processing and analysing satellite imagery has not been a straightforward task, with a lot of specialist knowledge required to make your data analysis ready. In addition, limited computing power made it only feasible to process and analyse individual satellite image acquisitions. This was not an issue as data even 10 years ago was not as numerous as it is today. For example, back in 2013, you would likely use Landsat 8 which has a 16 day revisit time at 30m resolution. In 2021 though, we now have access to Sentinel-2 with a revisit time of 5 days at 10m resolution. And if a scientist wished to develop any multitemporal application then they would likely rely on super-computers funded and managed by their institution. However, with the advances in computing power and the improvements in satellite revisit times meaning there is more data available now means that processing imagery on your desktop/laptop is no longer an effective approach.The introduction of the Copernicus Data Space Ecosystem is now making cloud processing methods accessible and open to earth observation scientists across Europe and the world. With its scalability, ease of use, and powerful data processing capabilities, the Copernicus Data Space Ecosystem is designed to be flexible and adaptable to the needs of all types of users, from researchers to intergovernmental institutions. In this talk, we will run a comparison exercise generating a multi-temporal satellite imagery derived product running a traditional workflow, before demonstrating an optimized version of the workflow using cloud processing APIs. A use case will be presented; where a simple harvest detection map will be derived using the Normalized Difference Vegetation Index (NDVI) and the Bare Soil Index (BSI). Using the difference in NDVI between the most recent and least recent timestamp, the BSI in the most recent timestamp, and thresholding these values, we classify pixels as either harvested or not harvested.The same workflow will then be run using the Sentinel Hub APIs that are available to all users of the Copernicus Data Space Ecosystem. The lines of code, amount of data downloaded and the time taken to process the data will then be compared demonstrating the efficiencies that can be gained from moving your satellite imagery processing to the cloud. 
Analysis on the Chemical Field Characteristics and Influencing Factors of Geothermal Water in Typical Area of North China Plain 
Authors: Xing Yifei
Published: March 2024

Xiongan New Area is located in the middle of North China Plain, with high background heat flow values and abundant geothermal resources. However, the degree of development of geothermal resources in Xiongan New Area is different, and the understanding of the hydrochemical formation and evolution is not comprehensive. Geothermal water and cold groundwater in Rongcheng uplift, Niutuozhen uplift, Baxian depression, Baoding depression and Gaoyang low uplift were sampled for hydrochemical analyses. There are two types of thermal reservoir in the study area: sandstone and karst thermal reservoir. Minghuazhen formation and Guantao formation had relatively shallow buried depth, and the hydrochemical types were mainly Cl·HCO3-Na and Cl-Na type. The main hydrochemical type of Wumishan formation was Cl·HCO3-Na. Due to the high degree of homogenization of karst reservoir, the spatial difference of hydrochemical characteristics was relatively small. From shallow to deep, the TDS value of geothermal water increased. Due to the influence of the water conduction in the fault zone, the mixing phenomenon of geothermal water in some deep Wumishan and Guantao formation occurred. The metamorphic coefficient and desulfurization coefficient of geothermal water in Wumishan formation were lower than that of Guantao formation, and the thermal storage was relatively closed and in relatively reduced state, while the sealing of geothermal water in Guantao formation and Minghuazhen formation was relatively poor. Our result is of great significance to understand the geothermal resources in Xiongan New Area and to promote the clean heating in winter in northern China.
Sulfur and fluorine degassing from Deccan Traps lavas inferred from pyroxene chemistry: potential for end-Cretaceous volcanic winters
Authors: Callegaro Sara , Baker Don R. , Renne Paul R. , Melluso Leone , Geraki Kalotina , Whitehouse Martin J. , De Min Angelo , Marzoli Andrea
Published: March 2024

The Cretaceous-Paleogene (K-Pg) mass extinction was a pivotal event in Earth's history and is attributed to the interplay of two major events—the Deccan Traps volcanism and the Chicxulub asteroid impact. We contribute to refine of our understanding of the volcanic stressor for this extinction by investigating the sulfur and fluorine budgets of Deccan lavas from the Western Ghats (India), spanning the K-Pg boundary [1].Sulfur and fluorine concentrations were analyzed in clinopyroxene phenocrysts from Deccan Traps lavas, by Synchrotron-light X-ray fluorescence (beamline I18, Diamond Light Source, U.K.), and ion probe (CAMECA IMS 1280 at Nordsim Laboratory, Swedish Museum of Natural History, Stockholm, SE), respectively. The results were divided by experimentally determined partition coefficients to calculate melt concentrations.Our analyses reveal variable magmatic volcanic fluorine concentrations ranging from 400 to 3000 parts per million, suggesting the potential for regional environmental impact. The highest sulfur concentrations, reaching up to 1800 parts per million, are observed in Deccan lavas emplaced just prior to the extinction interval, within a timeframe of 0.1 million years. In contrast, later basalts generally exhibit lower sulfur concentrations, only up to 750 parts per million.Independent evidence [2] supports that eruption of the Deccan flood basalts occurred in multiple voluminous eruptive pulses each lasting on the order of centuries, as typical of continental flood basalts. Our findings propose that the volcanic sulfur degassing associated with such activity may have led to repeated, short-lived global temperature drops, too short to be recorded by global paleotemperature record, albeit coupled with a global cooling trend. Sulfur-induced cold snaps likely imposed stress on ecosystems long before the decisive impact of the Chicxulub bolide at the end of the Cretaceous. [1] Sara Callegaro, et al., (2023) Recurring volcanic winters during the latest Cretaceous: Sulfur and fluorine budgets of Deccan Traps lavas. Sci. Adv. 9, eadg8284 doi:10.1126/sciadv.adg8284. [2] I. M. Fendley, et al., 2019. Constraints on the volume and rate of Deccan Traps flood basalt eruptions using a combination of high-resolution terrestrial mercury records and geochemical box models. Earth Planet Sci Lett. (524) 115721.  
The use of coal as ameliorant for soils with constraints for plant growth
Authors: Baumgartl Thomas , Baghbani Nima , Bucka Franziska
Published: March 2024

Increasing global population demands an increased intensity of use of agricultural land, but also to an extension of the use of land previously not suited for agriculture. Likewise, the stabilisation of degraded or reclaimed land e.g. from mining often requires intervention to create conditions which allow soil stabilisation by vegetation.Mine rehabilitation is often challenged by hard setting or clay rich substrates as the available substrate for shaping the final landform and amelioration is necessary. While chemical amelioration has time limited benefits, long-term physical/mechanical property improvements may lead to better outcomes above all in water limited environments.In this study we investigated the amelioration of clay substrate with coal with the objective to improve the physical, and potentially also chemical conditions for plant growth. Clay substrate was amended with up to 20%-wt lignite-type coal. The addition of coal occurred in two ways, as fine coal and as crushed coal, still containing aggregates. The clay and clay/coal mixtures were filled into boxes at a height of approximately 0.15m and a total volume of approx. 60 liters. Hydraulic properties were measured following consolidation of the substrate in multiple wetting-drying cycles until the substrate reached a constant height. Samples were extracted to characterise the substrates for their hydraulic and mechanical properties and their biotic activity potential. The test is based on quantifying the production of CO2 through the microbial oxidation of organic carbon compounds in the soil.The water retention curve tests and analysis (using HYPROP) showed in general an increase of the total pore volume with increase in coal content. The amount of plant available water increased with increase in coal content and was higher with the addition of fine coal, compared to the aggregated coal. The shear strength and cohesive strength decreased with addition of coal. The microbial activity tests showed only small increases in CO2 production and respiration, along with a low mineralisation rate of the added coal based carbon source. The results show, that the addition of a stable carbon source can be beneficial for the improvement of substrate properties.
Speleothems in northeastern Namibia as archives of hydroclimatic changes
Authors: Leitgeb Leonie , Koltai Gabriella , Dublyansky Yuri , Zhang Haiwei , Cheng Hai , Spötl Christoph
Published: March 2024

The hydroclimatic variability of southern Africa during the Quaternary is comparatively poorly know, partly due to the scarcity of suitable terrestrial paleoclimate archives in this semi-arid to arid region. Speleothems offer great potential for filling these knowledge gaps, and carbonate units exhibiting karst features are present in several regions. One such area is the Otavi Mountains of northeastern Namibia, where caves have developed in Neoproterozoic carbonate rocks. However, despite encouraging early work, only two speleothems from one Otavi cave have so far been studied using state-of-the-at techniques.As part of a research programme investigating the origin of caves in the Otavi Mountains, we were given permission to also sample speleothems, focusing on flowstones, which are locally abundant. Although most of these formations are currently inactive, there are local exceptions that allow to obtain proxy records covering also the Holocene. Most of the flowstones, however, were active during the late Pleistocene, with a marked growth pulse during the deglacial. Remarkably, none of the 70 dated subsamples formed during the Last Interglacial. The picture that emerges from this preliminary dataset suggests favoured speleothem growth (and higher average growth rates) during periods when the Intertropical Convergence Zone was shifted far to the south as a result of cold boreal conditions.While other parts of Namibia, such as the Namib Desert, may be more sensitive to hydroclimate changes leading to complete growth stops during interglacials, the higher rainfall and cooler temperatures in the Otavi Mountains open the door to obtain longer proxy records characterized by fewer hiatuses.
Plant physiological control of tropospheric ozone dry deposition over a maize agricultural field
Authors: Khan Anam , Hannun Reem , Gao Lun , Bernacchi Carl , Guan Kaiyu , Pederson Taylor , Stoy Paul
Published: March 2024

Tropospheric ozone is a phytotoxic air pollutant that reduces photosynthesis and vegetation biomass of major tree species and agricultural crops. Ozone induced damages can result in cascading impacts on the global carbon and water cycle. The stomatal uptake of ozone often correlates tightly with ozone induced losses in net photosynthesis and biomass. Furthermore, stomatal uptake represents a significant portion of ozone dry deposition and can directly impact the tropospheric ozone budget. The dual significance of stomatal ozone flux as directly impacting the global carbon cycle and as a tropospheric ozone loss pathway warrants continued monitoring of ecosystem ozone fluxes. However, measuring ozone fluxes has largely utilized chemiluminescence-based instruments that are difficult to operate and maintain in the field. The NASA Rapid Ozone Experiment (ROZE) is a recent advancement in ultraviolet (UV) absorption-based instruments and can achieve high sensitivity and sampling frequency making it possible to measure ozone fluxes without the use of chemiluminescence. Here, we analyze the influence of stomatal conductance on ozone dry deposition over the growing season in a maize (Zea mays) agricultural field in central Illinois, United States. We monitored ozone fluxes using the eddy covariance technique with 10 Hz measurements of wind velocity and ROZE ozone concentrations and partitioned the total ozone flux into stomatal and non-stomatal components. The stomatal component was estimated using the observed latent heat exchange with an inversion of the Penman-Monteith equation along with a stomatal optimization-based model using the gross primary productivity flux. We find that total ozone fluxes are highly coupled with gross primary productivity and evapotranspiration at this maize field. Furthermore, the observed deposition velocity of ozone is coupled with stomatal conductance throughout the growing season. These findings suggest that carbon and water fluxes from productive agricultural fields can be coupled with fluxes of phytotoxic air pollutants like ozone through stomatal regulation. Eddy covariance ozone fluxes monitored across tower networks can lead to an improved understanding of the control of natural ecosystems and agricultural fields on concentrations of air pollutants. Co-located carbon, water, and ozone flux observations will be valuable in testing and improving Earth system model representation of ozone dry deposition to predict how the impacts of global change on plant function will impact ozone dry deposition.
Predicting strong local wind with high-resolution nonhydrostatic numerical weather prediction model
Authors: Djurdjevic Vladimir , Tosic Milica , Lazic Irida
Published: March 2024

The nonhydrostatic multiscale model on the B grid (NMMB) was employed to forecast an episode of intense local Kosava wind in northeast Serbia. Kosava, a vigorously turbulent local wind, originates from the east or southeast near the Danube's "Iron Gate," moves westward over Belgrade, and then extends northward into the regions of Romania and Hungary. Typically attributed to a jet-effect wind within the narrow gorge of the "Iron Gate," it can reach maximum speeds exceeding 30 m/s. The NMMB model, with a horizontal resolution of 1.2 km, was utilized for the 2019 Kosava episode forecast. The high resolution, that surpasses the typical standards in numerical prediction models used by national meteorological services and other centers, can be crucial for accurately predicting strong wind gusts and capturing the specific dynamics and characteristics of the wind associated with the narrow gorge. The NMMB model results are compared with measured wind data and the results from models with lower resolutions.
Exploring spatial distribution and characterization of inorganic and organic phosphorus in temperate soils using NanoSIMS 
Authors: Lei Kaiyu , Bucka Franziska Barbara , Höschen Carmen , Hu Yahan , Kögel-Knabner Ingrid
Published: March 2024

For a comprehensive understanding of the phosphorus (P) storage and cycling in temperate soils, it is necessary to explore further the bonding pathways of organic P (Po) and inorganic P (Pi) to mineral surfaces and soil organic matter (SOM), and their interconnections with organic carbon (OC) at a micro-scale other than conventional bulk analysis. In the past decade, nanoscale secondary ion mass spectrometry (NanoSIMS) has been increasingly recognized as a promising imaging technique to understand soil biogeochemical processes, particularly in exploring organo-mineral associations in soils at the microscale (Mueller et al., 2023). However, its application in studying P, and the identification and distinction of Po and Pi remains challenging, hindering a comprehensive understanding of the P cycling in soils.In our study, four temperate soil types, including Cambisol, Luvisol, Phaeozem and Fluvisol, were taken from Bavarian Forest in South-East Germany. The pH of these soils ranges from 5.4 to 6.3, with poor to medium P stocks but distinct Po stocks in fine fractions (
Evaluation of leaf-atmosphere water fluxes and physiological characterization of plants subjected to an in situ elevated CO2 experiment in Central Amazon
Authors: Banstarck Marandola Gabriel , De Kauwe Martin G. , Garcia Sabrina , Ferreira Domingues Tomas , Montenegro Lapola David
Published: March 2024

The Amazon Rainforest vegetation responses to climate change are still far from being fully understood, especially when the focus is not on the forest canopy stratum. Concerning the changes in water use related to rising atmospheric CO2 levels, the distinct responses between forest strata of the Amazon are still uncertain. The project presented here consists in exploring data from an experimental study coupled with a mathematical modeling approach, with the goal to elucidate, in relation to rising CO2 levels, the transpiration responses of Central Amazon understorey plants, which may influence the entire region due to forest-atmosphere water flux disturbances. More specifically, we artificially increase the CO2 atmospheric concentration inside open-top chambers installed in the understory, providing a way to evaluate the response of the plants inside the chamber to the increased CO2 levels. With the estimation of carbon assimilation and stomatal conductance processes parameters defined by mathematical models, it is possible to characterize physiologically the response of the individuals in the experiment and compare the differences between control and treatment groups. Then, the impact of these changes in the understory transpiration is estimated by measuring the leaf area index of the understory and combining the obtained stomatal conductance parameters with another mathematical model, which makes it possible to compare the impact of the experimental treatment in the amount of water that travels from the understorey plants to the atmosphere through stomata. The results and methodology from this study, in addition to the importance to accomplishing the main goal mentioned above, are also relevant for the use of Dynamic Global Vegetation Models (DGVM), as the mathematical equations employed are also frequently used in DGVM studies. Finally, the experimental site being studied is also where the first Free-Air CO2 Enrichment experiment in the Amazon, known as AmazonFACE, will be conducted, so the open-top chambers data can be considered a source of basal knowledge for the large scale project that is being implemented at the same location.
Spatial cross-validation of wheat yield estimations using remote sensing and machine learning
Authors: Khechba Keltoum , Belgiu Mariana , Laamrani Ahmed , Dong Qi , Stein Alfred , Chehbouni Abdelghani
Published: March 2024

Integration of Machine Learning (ML) with remote sensing data has been successfully used to create detailed agricultural yield maps at both local and global scales. Despite this advancement, a critical issue often overlooked is the presence of spatial autocorrelation in geospatial data used for training and validating ML models. Usually random cross-validation (CV) methods are employed that fail to account for this aspect. This study aimed to assess wheat yield estimations using both random and spatial CV. In contrast to random CV where the data is split randomly, spatial CV involves splitting the data based on spatial locations, to ensure that spatially close data points are grouped together, either entirely in the training or in the test set, but not both. Conducted in Northern Morocco during the 2020-2021 agricultural season, our research uses Sentinel 1 and Sentinel 2 satellite images as input variables as well as 1329 field data locations to estimate wheat yield. Three ML models were employed: Random Forest, XGBoost, and Multiple Linear Regression. Spatial CV was employed across varying spatial scales. The province represents predefined administrative division, while grid2 and grid1 are equally sized spatial blocks, with a spatial resolution of 20x20km and 10x10 km respectively. Our findings show that when estimating yield with Random CV, all models achieve higher accuracies (R² = 0.58 and RMSE = 840 kg ha-1 for the XGBoost model) as compared to the performance reported when using spatial CV. The10x10 km spatial CV led to the highest R² value equal to 0.23 and an RMSE value equal to 1140 kg ha-1 for the XGBoost model, followed by the 20x20 km grid-based strategy (R² = 0.11 and RMSE = 1227 kg ha-1 for the XGBoost model). Province-based spatial CV resulted in the lowest accuracy with an R² value equal to 0.032 and an RMSE value of 1282 kg ha-1. These results confirm that spatial CV is essential in preventing overoptimistic model performance. The study further highlights the importance of selecting an appropriate CV method to ensure realistic and reliable results in wheat yield predictions as increased accuracy can deviate from real-world conditions due to the effects of spatial autocorrelation.  
Classification of defoliation of Scots Pine using SVM algorithm and Landsat imagery
Authors: Rodes Marina , Seidl Rupert , Ruiz Benito Paloma , Ángel Zavala Miguel , Aguado Inmaculada , Samblás Vives Eva , Fernández de Blas Cristopher , Rebollo Pedro , Tjerín Julián , Mariano García
Published: March 2024

Temperatures are expected to rise 1.5ºC for 2100 due to climate change caused by anthropogenic emissions. These risen of temperatures are causing an increase in frequency and intensity of drought events that are expected to get even more frequent and more extreme in the following decades. Most predictions suggests that drought stress will cause a large-scale tree mortality, species distribution range contractions and a general productivity loss throughout this century. Defoliation represents an early stage of dieback, at which some silvicultural practices can be done to reduce competence or to improve water retention. Therefore, identifying and mapping these areas is of crucial importance to forest managers in the context of global change. The aim of this study is to develop a classification model to differentiate die-off and healthy Scots Pine plots using field data and Landsat time series and to extrapolate the model results to other areas of the species’ distribution. We have 51 plots (17 m ~ Landsat pixel) in four sites with healthy (= 30% defoliated) areas for which we collected dasometric information along with defoliation and mortality. We downloaded, decomposed, and modelled Landsat time series (1985-2023) of Tasseled Cap components and fitted linear models since the last severe drought (2017) that affected Pinus sylvestris populations. A set of candidate explanatory variables were built including the slope of the linear model between 2017 and 2024, mean trend values from 2022 and mean amplitude from 2022.  Field data were randomly divided in two independent groups (train and test plots). This process was repeated 100 times and a support vector machines (SVM) model was calibrated for every possible combination of explanatory variables. The best candidate model was chosen according to the model performance metrics of the 100 calibrated models. The best model had an AUC > 96.97%, an OAA>88.23% and a die-off prediction rate over 83.3% for the 75 out of 100 repetitions. Applying model ensemble to all the plots an AUC = 97.5%, a die-off prediction rate of 95% was obtained. With this work we conclude that Landsat info from 2017 can successfully classify plots into healthy and non-healthy ones. The results of the model are good enough to extrapolate to areas of similar conditions to our study plots and will be, hence, applicable to most of the Pinus sylvestris distribution. 
Non-matching predictions from different models simulating the effects of elevated atmospheric CO2 on the Amazon forest’s functional diversity
Authors: Blanco Carolina C. , Rius Bianca F. , Darela-Filho João Paulo , Cardeli Barbara , Aleixo Izabela , Scheiter Simon , Langan Liam , Joshi Jaideep , Hofhansl Florian , Singh Shipra , De Paula Mateus Dantas , Hickler Thomas , Ongole Shasank , Higgins Steven , Fleischer Katrin , Rammig Anja , Lichstein Jeremy , Lapola David M.
Published: March 2024

The continuous rising of atmospheric carbon dioxide (CO2) concentration is undoubtedly affecting the resilience of tropical forests worldwide. However, the magnitude of such effects is poorly known, limiting our capacity to assess the vulnerability of tropical forests and to improve their representation by models. Functional diversity (FD) is an important component of biodiversity enhancing ecosystem resilience, as high FD can provide higher response diversity and capacity to buffer against climate change. How FD is represented by different Dynamic Global Vegetation Models (DGVMs) may affect how such models predict the impacts of environmental changes on hyperdiverse ecosystems. We compared simulations of five trait-based DGVMs (i.e., with flexible, variable traits) constrained with data from the Amazon rainforest in the scope of the AmazonFACE project. Simulations were conducted considering initial high or low diversity scenarios under ambient and elevated CO2 (400 ppm and 600 ppm, respectively). We searched for correspondence between the functional identity of simulated plant strategies and their ecophysiological performances under elevated CO2. As models take different approaches to simulating functional trait distributions and they differ in their structure and in the trade-offs implemented, we found important intermodel differences in simulated results. Nevertheless, we took advantage of these differences in order to assess the most likely scenarios in terms of functional composition under elevated CO2, as well as to give feedback for better harmonization of model inputs and outputs and future model improvements. In the face of the pessimistic scenarios that project a continuous increase in CO2 levels, resolving the divergent responses among model predictions is critical, given the global importance of the Amazon rainforest's biodiversity and climate regulation, as well as the approximately 30 million people that directly or indirectly depend on the forest for their well-being.