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Introduction
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December 1992 - present
Education
December 1992 - November 1998
Publications
Publications (620)
Nitrogen (N) fertilization is crucial to sustain global food security, but fertilizer N production is energy-demanding and subsequent environmental N losses contribute to biodiversity loss and climate change. N losses can be mitigated be interfering with microbial nitrification, and therefore the use of nitrification inhibitors in enhanced efficien...
Estuaries have been recognized as one of the major sources of greenhouse gases (GHGs) in aquatic systems; yet we still lack insights into the impact of both anthropogenic and natural factors on the dynamics of GHG emissions. Here, we assessed the spatiotemporal dynamics and underlying drivers of the GHG emissions from the Scheldt Estuary with a foc...
Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species1,2. Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies3,4. Here, leveraging global tree databases5-7, we explore how the phy...
The Pinios River Basin (PRB) is the most intensively cultivated area in Greece, which hosts numerous industries and other anthropogenic activities. The analysis of water samples collected monthly for ~1 ½ years in eight monitoring sites in the PRB revealed nitrate pollution of organic origin extending from upstream to downstream and occurring throu...
The carbon isotope composition of respired CO2 (δ13CR) and bulk organic matter (δ13CB) of various plant compartments informs about isotopic fractionation and substrate of respiratory processes, crucial to advance understanding of carbon allocation in plants. Nevertheless, its variation across organs, species, and seasons remains poorly understood....
The Pinios river basin (PRB) is the most intensively cultivated area in Greece, which hosts numerous industries and other anthropogenic activities. The analysis of water samples collected monthly for ~1 ½ years in eight monitoring sites in the PRB revealed nitrate pollution of organic origin extending from upstream to downstream and occurring throu...
The steadily growing demand for fertilizers and increasing interest for organic inputs result in rapid expansion and diversification of the solid nitrogen (N) fertilizer market. Fertilizer legislations distinct different fertilizers classes (i.e. organic, organo-mineral, inorganic), but standards and norms related to nutrient- and carbon origin rem...
With an increasing world population of nearly eight billion which is expected to expand towards nine billion by 2050, future food demands will rise unavoidably. Primary productivity of crop is at the center of the food and feed value chain. Excessive and low efficiency fertilization cause severe environmental and ecological problems, along with eco...
Biodiversity is an important component of natural ecosystems, with higher
species richness often correlating with an increase in ecosystem productivity. Yet,
this relationship varies substantially across environments, typically becoming less
pronounced at high levels of species richness. However, species richness alone cannot reflect all important...
Organic matter accumulation in soil is understood as the result of the dynamics between mineral-associated (often more decomposed, microbial derived) organic matter and free particulate (often less decomposed, plant derived) organic matter. However, at global scales, the patterns and drivers behind main SOC reservoirs are not well understood and re...
The biophysical drivers that affect coffee quality vary within and among farms. Quantifying their relative importance is crucial for making informed decisions concerning farm management, marketability and profit for coffee farmers. The present study was designed to quantify the relative importance of biophysical variables affecting coffee bean qual...
Tropical montane forests store high amounts of soil organic carbon (SOC). However, global warming may affect these stocks via enhanced soil respiration. Improved insight into the temperature response of SOC respiration can be obtained from in and ex situ warming studies. In situ warming via translocation of intact soil mesocosms was carried out alo...
Blue mussels (Mytilus edulis) are an abundant and economically important species across the North Sea. Partly because of their potent filter feeding and associated shell biofilm, they are able to influence and alter the surrounding marine ecosystem. As a result of proliferating offshore wind farms (OWFs), whose turbine foundations are rapidly colon...
Hitherto, studies on shade and postharvest processing (PHP) effects on coffee quality across elevation ranges (ER) are limited. The effects of shade, PHP and their interaction on quality and caffeine, sucrose and chlorogenic acids (CGAs) contents of arabica coffee beans in lowland and midland were evaluated. The results showed that physical, total...
The Atalanti basin is an intensively cultivated area in central Greece, facing groundwater quality deterioration threats due to natural and anthropogenic-related contamination sources. A combination of statistical and hydrogeochemical techniques, and stable isotope compositions (δ²H-H2O and δ¹⁸Ο-Η2Ο, δ¹⁵Ν-ΝΟ3⁻ and δ¹⁸Ο-ΝΟ3⁻, δ³⁴S-SO4²⁻ and δ¹⁸O-SO4...
Coffee quality and biochemical composition are believed to vary with geographical origin. Seed weight, quality attributes, and contents of caffeine, sucrose and chlorogenic acids of green arabica coffee beans from five coffee regions (eastern or Harar, southern, southwestern, western and northwestern regions of Ethiopia) and 24 coffee localities ac...
Nitrogen (N) fertilization is crucial to sustain global food security, but fertilizer N production is energy-demanding and subsequent environmental N losses contribute to biodiversity loss and climate change. To mitigate the environmental impact of N-fertilizers, nitrification inhibitors can be applied to produce so-called enhanced efficiency ferti...
Nitrogen is the most crucial element in the production of nutritious feeds and foods. The production of reactive nitrogen by means of fossil fuel has thus far been able to guarantee the protein supply for the world population. Yet, the production and massive use of fertilizer nitrogen constitute a major threat in terms of environmental health and s...
Questions
Ecological succession is the process during which ecosystems recover after disturbances. Studies investigating community reassembly during tropical forest succession have rarely compared lianas to trees. We addressed two questions: (1) how do changes in stem density, total basal area and species richness of lianas and trees compare throug...
The rapid development of blue economy and human use of offshore space triggered the concept of co-location of marine activities and is causing diverse local pressures on the environment. These pressures add to, and interact with, global challenges such as ocean acidification and warming. This study investigates the combined pressures of climate cha...
jats:p>Abstract. Climate change has the potential to increase surface ozone (O3) concentrations, known as the “ozone–climate penalty”, through changes to atmospheric chemistry, transport and dry deposition. In the tropics, the response of surface O3 to changing climate is relatively understudied but has important consequences for air pollution and...
Meteorological stations are rare in the tropics and satellite products often do not perform optimal. This leads to uncertainty in modelled regional climatic trends and may lead to opposing trends in prediction of future climate. This is particularly problematic for the Congo basin, where station coverage decreased significantly during the last few...
The lack of field-based data in the tropics limits our mechanistic understanding of the drivers of net primary productivity (NPP) and allocation. Specifically, the role of local edaphic factors - such as soil parent material and topography controlling soil fertility as well as water and nutrient fluxes - remains unclear and introduces substantial u...
Tropical montane forests store large amounts of carbon (C), nitrogen (N), and phosphorus (P) in soil. These soil C, N, and P pools are vulnerable to increased losses due to the increasing local temperatures. To gain better insight into the effects of climate warming on biogeochemistry in montane forests in Africa, we established study plots along a...
The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we...
A coupled methodology of nitrogen isotopes, hydrogeochemical characterization, multivariate statistical analysis, and SIAR Bayesian modeling has been employed to identify the sources of NO3⁻ and N transformation processes in three alluvial aquifers (Schinos, Thiva, and Central Evia) located in central Greece where geogenic Cr(VI) co-occurs with agr...
Green coffee bean quality and biochemistry are influenced by environmental variables. The present study was designed to study the influence of soil temperatures and soil chemistry on bean physical attributes, bean quality (assessed by three internationally trained, experienced, and certified Q-grade cuppers licensed by the Specialty Coffee Associat...
Secondary forests constitute an increasingly important component of tropical forests worldwide. Although cycling of essential nutrients affects recovery trajectories of secondary forests, the effect of nutrient limitation on forest regrowth is poorly constrained. Here we use three lines of evidence from secondary forest succession sequences in cent...
Forest fragmentation increases the proportion of edge area and this, in turn, induces changes in forest structure,
species composition and microclimate. These factors are also strongly determined by the forest management
regime. Although the interactive effects of edges and density on forest plant communities have been extensively
studied, little i...
The soil nitrogen (N) cycle in cold terrestrial ecosystems is slow and organically bound N is an important source of N for plants in these ecosystems. Many plant species can take up free amino acids from these infertile soils, either directly or indirectly via their mycorrhizal fungi. We hypothesized that plant community changes and local plant com...
Rationale:
Stable isotope approaches are increasingly applied to better understand the cycling of inorganic nitrogen (Ni ) forms, key limiting nutrients in terrestrial and aquatic ecosystems. A systematic comparison of the accuracy and precision of the most commonly used methods to analyze δ15 N in NO3 - and NH4 + and inter-laboratory comparison t...
Aquatic losses of nutrients are important loss vectors in the nutrient budgets of tropical forests. Traditionally, research has focused mainly on losses of inorganic nutrient forms, whereas the potential contribution of organic and particulate losses to the total nutrient export budget is much less constrained. In this study, we quantified full aqu...
Agricultural intensification and forest conservation are often seen as incompatible. Agricultural interventions can help boost food security for poor rural communities but in certain cases can exacerbate deforestation, known as the rebound effect. We tested whether coupling agricultural interventions with participatory forest zoning could improve f...
The Congo basin is home to the second-largest tropical forest in the world. Therefore, it plays a crucial role in the regional water cycle, the global carbon cycle and the continental greenhouse gas balance. Yet very few field-based data on related processes exist. In the wake of global change, there is a need for a better understanding of the curr...
The net primary productivity (NPP) of tropical forests is an important component of the global terrestrial carbon (C) cycle. The lack of field-based data, however, limits our mechanistic understanding of the drivers of NPP and C allocation. In consequence, the role of local edaphic factors for forest growth and C dynamics is unclear and introduces...
Background
Across the tropics, the share of secondary versus primary forests is strongly increasing. The high rate of biomass accumulation during this secondary succession relies on the availability of essential nutrients, such as nitrogen (N). Nitrogen primarily limits many young secondary forests in the tropics. However, recent studies have shown...
Rivers act as a natural source of greenhouse gases (GHGs). However, anthropogenic activities can largely alter the chemical composition and microbial communities of rivers, consequently affecting their GHG production. To investigate these impacts, we assessed the accumulation of CO2, CH4, and N2O in an urban river system (Cuenca, Ecuador). High var...
Montane forests are characterized by high biodiversity, endemism, and strong elevational environmental gradients. The latter attribute makes them also suitable as a “natural laboratory” for studying the effects of environmental parameters on ecosystem functions. To provide better insight into the carbon cycle of Afromontane ecosystems, we used an e...
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we...
Aims
This study has been carried out to determine the spatial variability of faba bean seed Fe, Zn and Se content across agro-ecological zones in central and southwestern Ethiopia, where it is an important source of protein in the diet. The study assessed whether soil properties, arbuscular mycorrhizal fungi (AMF), faba bean characteristics and gen...
The individual and interaction effects of elevation, production system (PS), shade and postharvest processing (PHP) on the ratio of dry beans to red cherries and the green bean physical quality features and defects of arabica coffee in southwestern Ethiopia were evaluated. The results showed that, with increasing elevation, the proportions of the t...
Rationale:
Information on the isotopic composition of nitrous oxide (N2 O) at natural abundance supports the identification of its source and sink processes. In recent years, a number of mass spectrometric and laser spectroscopic techniques have been developed and are increasingly used by the research community. Advances in this active research ar...
Background
Across the tropics, the share of secondary versus primary forests is strongly increasing. The high rate of biomass accumulation during this secondary succession relies on the availability of essential nutrients, such as nitrogen (N). Nitrogen primarily limits many young secondary forests in the tropics. However, recent studies have shown...
NASAs Global Ecosystem Dynamics Investigation (GEDI) is collecting space-borne full waveform lidar data with a primary science goal of producing accurate estimates of forest aboveground biomass density (AGBD). This paper presents the development of the models used to create GEDIs footprint-level (~25 m) AGBD (GEDI04_A) product, including a descript...
Carbon (C) mineralization and turnover in soil rely on complex interactions among environmental variables that differ along latitudinal gradients. This study aims to quantify the relationship between the variation in δ13C signature with soil depth (∆δ13C) and soil C turnover across a large geo-climatic gradient. Thirteen grassland sites were sample...
Tropical montane forest store high amounts of soil organic carbon. However, global warming may affect these carbon stocks by enhancing soil organic carbon respiration. Better insight into temperature response of soil organic carbon respiration can be obtained from in and ex situ warming studies. In situ warming via translocation of intact soil meso...
The aim of this research was to evaluate the relevance of using deuterium oxide (2H2O) and bio-impedance analysis (BIA) to assess size and function of the interstitium for urological research. Nineteen volunteers were recruited to this prospective trial combining ingestion of 2H2O and BIA. Blood samples were obtained every 10 min after ingestion of...
Globally, tropical forests are assumed to be an important source of atmospheric nitrous oxide (N 2 O) and sink for methane (CH 4). Yet, although the Congo Basin comprises the second largest tropical forest and is considered the most pristine large basin left on Earth, in situ N 2 O and CH 4 flux measurements are scarce. Here, we provide multi-year...
The recent introduction of soybean cultivation in Belgium and several other north-western European countries holds great potential for sustainable agriculture. Agricultural practices must be fine-tuned to optimise yield and quality before soybean will become a profitable crop for Belgian farmers. The effect of inoculation and N fertilisation on cro...
is collecting spaceborne full waveform lidar data with a primary science goal of producing accurate estimates of forest aboveground biomass density (AGBD). This paper presents the development of the models used to create GEDI's footprint-level (~25 m) AGBD (GEDI04_A) product, including a description of the datasets used and the procedure for final...
Coffee is an important crop in the global south. However, ongoing changes in the climate system reinforce the need to quantify coffee plants' ecological and eco-physiological traits to assure coffee production in the future. One way to assess how environmental changes affect coffee performance is via leaf traits, most notably leaf carbon and nitrog...
Anthropogenic nitrogen inputs cause major negative environmental impacts, including emissions of the important greenhouse gas N2O. Despite their importance, changes in terrestrial N loss pathways driven by global change and spatial redistribution of N inputs are highly uncertain. We present a novel coupled soil-atmosphere isotope model (IsoTONE) to...
The role of soil in the global carbon cycle and carbon–climate feedback mechanisms has attracted considerable interest in recent decades. Consequently, development of simple, rapid, and inexpensive methods to support the studies on carbon dynamics in soil is of interest. Near-infrared spectroscopy (NIRS) has emerged as a rapid and cost-effective me...
Studies on sediment export from tropical forest watersheds are scarce. Of the assessments that do exist, most are of larger rivers or are model-based and lack validation with measured data. Understanding the mechanisms of sediment export dynamics in forested headwaters is important for assessing downstream effects and as a baseline for net impacts...
Information on soil properties is crucial for soil preservation, the improvement of food security, and the provision of ecosystem services. In particular, for the African continent, spatially explicit information on soils and their ability to sustain these services is still scarce. To address data gaps, infrared spectroscopy has achieved great succ...
Abiotic fixation and defixation of ammonium (NH4+) in silicate interlayers are common processes in paddy soils, owing to their often high levels of 2:1 type clay minerals. Fixed NH4+ hence forms a buffer during the supply and loss of plant-available N. The soil redox potential (Eh) is suspected to influence NH4+ (de)fixation by its impact on the ne...
Tropical forests are a key component of the global carbon cycle and climate change mitigation. Field- or LiDAR-based approaches enable reliable measurements of the structure and above-ground biomass (AGB) of tropical forests. Data derived from digital aerial photogrammetry (DAP) on the unmanned aerial vehicle (UAV) platform offer several advantages...
Anaerobic decomposition of organic carbon (OC) in submerged rice
paddies is coupled to the reduction of alternative soil electron acceptors,
primarily Fe3+. During reductive dissolution of Fe3+ from
pedogenic oxides, previously adsorbed native soil organic carbon (SOC) could
be co-released into solution. Incorporation of crop residues could hence
i...