Ralf Kiese

• PD Dr.
• Head of Department at Karlsruhe Institute of Technology

Tree growth and forest development depend to a large degree on climatic conditions. This is mostly because they are determining primary production, respiration losses, water demand and availability. The complex nature interacting climate components, however, represents a challenge if carbon sequestration and forest growth should be evaluated under...

We applied 15 N labelled cattle slurry over one year to large grassland lysimeters in Southern Germany to study its importance for plant nitrogen (N) nutrition not only in the year of application, but also in the following four years, and for both current and future climatic conditions. In the year of 15 N fertilizer application, the recovery of 15...

Tropical forests play an important role in the greenhouse gas exchange between the biosphere and atmosphere. Despite having the second largest tropical forest globally, the Congo Basin is generally understudied and ground-based greenhouse gas flux data are lacking. In this study, high-frequency measurements spanning 16 months from automated and man...

Climate change poses a significant threat to agriculture, primarily through yield losses due to droughts and heatwaves. The flowering phase is a particularly critical period during which many crops are highly susceptible to heat, resulting in long-term damage and substantial yield reduction. By imposing the large-scale atmospheric circulation of th...

Legumes in crop rotations are considered an ecological intensification management practice to reduce nitrogen (N) losses to the environment. However, studies on N allocation and loss on adjacent sites with the same pedoclimatic conditions but different management histories, i.e. organic farming (OF) with frequent legume cultivation and occasional o...

Grasslands make up the majority of agricultural land and provide fodder for livestock. Information on grassland yield is very limited as the fodder is directly used at the farms. Data on grassland yields would be needed, however, to inform politics and stakeholders on grassland ecosystem services and inter-annual variations. Grassland yield pattern...

Conservation agriculture, which involves minimal soil disturbance, permanent soil cover, and crop rotation, has been widely adopted as a sustainable agricultural practice globally. However, the effects of conservation agriculture practices on soil N2O emissions and crop yield vary based on geography, management methods, and the duration of implemen...

Background and aims Organic amendments directly affect soil N transformations, while the direction and magnitude of these effects remain uncertain. Most previous studies through laboratory incubation experiments without plants likely neglected the feedback interactions of plant, thereby limiting the applicability in field conditions. This study aim...

Global fluvial ecosystems are important sources of greenhouse gases (CO2, CH4, and N2O) to the atmosphere, but their estimates are plagued by uncertainties due to unaccounted spatio-temporal variabilities in the fluxes. In this study, we tested the potential of modeling these variabilities using several machine learning models (ML) and three differ...

Food, feed, and fiber production needs to increase to support demands of the growing population in Sub‐Saharan Africa (SSA), while soil fertility continues to decline. Intercropping, the cultivation of two or more crop species on the same field, can provide yield benefits and is suggested to positively affect soil organic carbon (C) and nitrogen (N...

Grasslands are the basis for milk and meat production in alpine and pre-alpine regions, where climate warming is occurring twice as fast as in global average. Warmer and drier conditions have been found to lead to versatile effects on grassland productivity and yields depending on pedo-climatic conditions. Experimentally, it has been discovered tha...

Warming as a climate change phenomenon affects soil organic matter dynamics, especially in high elevation ecosystems. However, our understanding of the controls of soil organic matter mineralization and dynamics remains limited, particularly in alpine (above treeline) and subalpine (below treeline) grassland ecosystems. Here, we investigated how do...

Soil gross mineral N production and consumption processes are crucial regulators of plant productivity and N loss from croplands. Substituting synthetic fertilizers by integrating legumes in cultivation systems is common in organic farming, but research on its long-term impact on dynamics of gross soil N transformation and associated environmental...

Aim Significant progress has been made in understanding the links between biodiversity and ecosystem functioning in both experimental and real-world ecosystems. Yet, we have limited understanding to which extent biodiversity affects ecosystem functioning in natural heterogeneous environments and whether changes in ecosystem functions are related to...

Global fluvial ecosystems are important sources of greenhouse gases (CO 2 , CH 4, and 14 N 2 O) to the atmosphere, but their estimates are plagued by uncertainties due to unaccounted spatio-temporal variabilities in the fluxes. In this study, we tested the potential of modeling these variabilities using several machine learning models (ML) and thre...

Tropical forests play an important role in the greenhouse gas exchange between biosphere and atmosphere. Despite holding the second largest tropical forest globally, the Congo basin is generally understudied and ground based greenhouse gas flux data are lacking. In this study, high frequency measurements spanning of sixteen months from automated an...

Global climate change threatens ecosystem functioning worldwide. Forest ecosystems are particularly important for carbon sequestration, thereby buffering climate change and providing socio-economic services. However, recurrent stresses, such as heat waves, droughts and floods can affect forests with potential cascading effects on their carbon sink...

The need to develop and provide integrated observation systems to better understand and manage global and regional environmental change is one of the major challenges facing Earth system science today. In 2008, the German Helmholtz Association took up this challenge and launched the German research infrastructure TERrestrial ENvironmental Observato...

Intensive fertilization of grasslands with cattle slurry can cause high environmental nitrogen (N) losses in form of ammonia (NH3), nitrous oxide (N2O), and nitrate (NO3⁻) leaching. Still, knowledge on short-term fertilizer N partitioning between plants and dinitrogen (N2) emissions is lacking. Therefore, we applied highly ¹⁵N-enriched cattle slurr...

Lotic ecosystems traversing mixed land-use landscapes are sources of GHGs to the atmosphere, but their emission strength is uncertain due to longitudinal GHG heterogeneities. In this study, we quantified N 2 O (as well as CO 2 and CH 4 concentrations) and N 2 concentrations and several water quality parameters along the Rhine river and the Mittella...

Lotic ecosystems are sources of greenhouse gases (GHGs) to the atmosphere, but their emissions are uncertain due to longitudinal GHG heterogeneities associated with point source pollution from anthropogenic activities. In this study, we quantified summer concentrations and fluxes of carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and dini...

Essential soil functions such as plant productivity, C storage, nutrient cycling and the storage and purification of water all depend on soil biological processes. Given this insight, it is remarkable that in modeling of these soil functions, the various biological actors usually do not play an explicit role. In this review and perspective paper we...

Soil microorganisms are the major players controlling the soil carbon (C) and nutrient cycling, however the extent to which the functional properties of soil microorganisms will alter with climate change in mountain grasslands is still unclear. To simulate future climatic conditions (higher temperature and less precipitation), intact plant-soil mes...

The carbon isotope composition (δ13CLeaf) of C3 plant leaves provides valuable information on the carbon-water cycle of vegetation and their responses to climate change within terrestrial ecosystems. However, global applications of δ13CLeaf are hindered by a lack of global long-term spatial maps (isoscapes) that capture vegetation δ13CLeaf variatio...

The need to develop and provide integrated observation systems to better understand and manage global and regional environmental change is one of the major challenges facing Earth system science today. In 2008, the German Helmholtz Association took up this challenge and launched the German research infrastructure TERrestrial ENvironmental Observato...

Mountainous grassland soils are considered one of the most unique biological hotspots, rich in organic carbon (OC). At the same time, they are exposed to great threats, as climate warming is more pronounced in mountainous regions than in lowland areas. In this study, we assessed the effect of simulated warming (+1K, +2K, and +3K) on OC stocks and s...

Stream ecosystems are actively involved in the biogeochemical cycling of carbon (C) and nitrogen (N) from terrestrial and aquatic sources. Streams hydrologically connected to peatland soils are suggested to receive significant quantities of particulate, dissolved, and gaseous C and N species, which directly enhance losses of greenhouse gases (GHGs)...

Upscaling chamber measurements of soil greenhouse gas (GHG) fluxes from point scale to landscape scale remain challenging due to the high variability in the fluxes in space and time. This study measured GHG fluxes and soil parameters at selected point locations (n=268), thereby implementing a stratified sampling approach on a mixed-land-use landsca...

Lotic ecosystems transversing mixed land-use landscapes are sources of GHGs to the atmosphere, but their emissions are uncertain due to longitudinal GHG heterogeneities. In this study, we quantified summer CO 2 , CH 4 , N 2 O, and N 2 concentrations, as well as several water quality parameters along the Rhine river and the Mittelland canal, two cri...

Spatio-temporal information on grasslands traits (e.g., biomass, plant nitrogen concentration) are valuable information for precision agriculture and for the quantification of regional carbon and nitrogen (N) cycles. Remote sensing approaches showed a high potential to provide this kind of information. In this study, we aim to explore the potential...

The dataset contains yearlong monthly measurements (June 2020 to April 2022) of water quality parameters, CO2, CH4 and N2O concentrations from 23 streams, 3 drainage ditches and 2 wastewater effluent sites within within the Loisach, Schwingbach and Neckar catchments in Germany. The study sites covered various upstream land uses (croplands, wetlands...

The dataset contains yearlong monthly measurements (January 2019 to Febuary 2020) of water quality parameters, CO2, CH4 and N2O concentrations from 59 stream sites within the Kenyan part of the Mara River basin. The study sites covered various upstream land uses (croplands, savanah grasslands and forests) as well as stream orders (1-8). Measurement...

A major societal challenge is to produce sufficient food for a growing global population while simultaneously reducing agricultural nitrogen pollution to within safe environmental boundaries. Here we use spatially-resolved, process-based simulations of cereal cropping systems (at 0.5° resolution) to show how redistribution of nitrogen fertiliser us...

Anthropogenic activities increase the contributions of inland waters to global greenhouse gas (GHG; CO2, CH4, and N2O) budgets, yet the mechanisms driving these increases are still not well constrained. In this study, we quantified year-long GHG concentrations, fluxes, and water physico-chemical variables from 28 sites contrasted by land use across...

Greenhouse gas emissions from headwater streams are linked to multiple sources influenced by terrestrial land use and hydrology, yet partitioning these sources at catchment scales remains highly unexplored. To address this gap, we sampled year-long stable water isotopes (δ18O and δ2H) from 17 headwater streams differing in catchment agricultural ar...

Upscaling chamber measurements of soil greenhouse gas (GHG) fluxes from points to landscape scales remain challenging due to high variability of fluxes in space and time. This study measured GHG fluxes and soil parameters at selected point locations (n=268), thereby implementing a stratified sampling approach on a mixed land-use landscape (~5.8 km2...

Purpose This study presents three contrasting applications using calculation tools for greenhouse gas (GHG) emissions and carbon footprints (C-footprint) that were specifically developed for rice production. This includes a new digital information system for labeling, tracking, and optional auditing of product-specific C-footprints that complements...

High N-fertilizer applications to conventional vegetable production systems are associated with substantial emissions of NH3, a key substance that triggers haze pollution and ecosystem eutrophication and thus, causing considerable damage to human and ecosystem health. While N fertilization effects on NH3 volatilization from cereal crops have been r...

Drainage and reduction in precipitation due to climate change have led to global declines in the water table (WT) of pristine peatlands, which have increased ecosystem releases of carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) and decreased emissions of methane (CH 4 ). However, the trade-offs in these changes on net greenhouse gas (GHG) balances...

Anthropogenic activities increase the contributions of inland waters to global greenhouse gas (GHG; CO2, CH4, and N2O) budgets, yet the mechanisms driving these increases are still not well constrained. In this study, we quantified year-long GHG concentrations and fluxes, as well as water physico-chemical variables from 23 streams, 3 ditches, and 2...

Anthropogenic activities increase the contributions of inland waters to global greenhouse gas (GHG; CO 2 , CH 4, and N 2 O) budgets, yet the mechanisms driving these increases are still not well constrained. In this study, we quantified year-long GHG concentrations and fluxes, as well as water physico-chemical variables from 23 streams, three ditch...

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 the translocation of intact soil mesocosms was carried out...

Agricultural food production is a main driver of global greenhouse gas emissions, with unclear pathways towards carbon neutrality. Here, through a comprehensive life-cycle assessment using data from China, we show that an integrated biomass pyrolysis and electricity generation system coupled with commonly applied methane and nitrogen mitigation mea...

Spatial information on grassland biomass and nitrogen concentration are important for precision agriculture. We compare machine learning with hybrid models to estimate both parameters with Sentinel-2 data, and test hybrid models with hyperspectral EnMAP data.

Background Globally, rice systems are a major source of atmospheric CH 4 and for major rice‐producing countries, such as Vietnam, CH 4 as well as N 2 O emissions from agricultural land used for rice production may represent about one‐fourth of total national anthropogenic greenhouse gas (GHG) emissions. However, national‐scale estimates of GHG emis...

Low nitrogen (N) use efficiency of broadcast slurry application leads to nutrient losses, air and water pollution, greenhouse gas emissions and—in particular in a warming climate—to soil N mining. Here we test the alternative slurry acidification and injection techniques for their mitigation potential compared to broadcast spreading in montane gras...

Germany's 2018–2020 consecutive drought events resulted in multiple sectors – including agriculture, forestry, water management, energy production, and transport – being impacted. High-resolution information systems are key to preparedness for such extreme drought events. This study evaluates the new setup of the one-kilometer German drought monito...

Accurate quantification of landscape soil greenhouse gas (GHG) exchange from chamber measurements is challenging due to the high spatial‐temporal variability of fluxes, which results in large uncertainties in upscaled regional and global flux estimates. We quantified landscape‐scale (6 km² in central Germany) soil/ecosystem respiration (SR/ER‐CO2),...

Greenhouse gas fluxes (CO 2 , CH 4 , and N 2 O) from African streams and rivers are under-represented in global datasets, resulting in uncertainties in their contributions to regional and global budgets. We conducted year-long sampling of 59 sites in a nested-catchment design in the Mara River, Kenya in which fluxes were quantified and their underl...

Grasslands are an important part of pre-Alpine and Alpine landscapes. Despite the economic value and the significant role of grasslands in carbon and nitrogen (N) cycling, spatially explicit information on grassland biomass and quality is rarely available. Remotely sensed data from unmanned aircraft systems (UASs) and satellites might be an option...

Worldwide, rice production contributes about 10% of total greenhouse gas (GHG) emissions from the agricultural sector, mainly due to CH4 emissions from continuously flooded fields. Alternate Wetting and Drying (AWD) is a promising crop technology for mitigating CH4 emissions and reducing the irrigation water currently being applied in many of the w...

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 eddy-covariance method provides the most direct estimates for fluxes between ecosystems and the atmosphere. However, dispersive fluxes can occur in the presence of secondary circulations, which can inherently not be captured by such single-tower measurements. In this study, we present options to correct local flux measurements for such large-sc...

Many experiments have shown that biodiversity enhances ecosystem functioning. However, we have little understanding of how environmental heterogeneity shapes the effect of diversity on ecosystem functioning and to what extent this diversity effect is mediated by variation in species richness or species turnover. This knowledge is crucial to scaling...

Increasing tropospheric concentrations of ozone (e[O3]) and carbon dioxide (e[CO2]) profoundly perturb terrestrial ecosystem functions through carbon and nitrogen cycles, affecting beneficial services such as their capacity to combat climate change and provide food. However, the interactive effects of e[O3] and e[CO2] on these functions and service...

Grasslands are an important part of pre-Alpine and Alpine landscapes. Despite the economic value and the significant role of grasslands in carbon and nitrogen (N) cycling, spatially explicit information on grassland biomass and quality is rarely available. Remotely sensed data from unmanned aircraft systems (UAS) and satellites might be an option t...

Climate warming and management will likely affect carbon (C) fluxes of montane grassland ecosystems. In this study, we assessed the effect of simultaneous warming (+2°C) and decreased precipitation (−25%) on carbon exchange of montane grasslands in S‐Germany by translocating large intact plant‐soil cores from a high altitude to a low altitude site....

Pastures and natural grasslands are an important part of the pre-Alpine and Alpine landscape ranging from intensive grasslands in the lower regions to highly diverse seasonal mountain pastures and specialized natural ecosystems. These grasslands play an important economic role as they provide the basis for dairy and cattle production. Besides, they...

The 2018–2020 consecutive drought events in Germany resulted in impacts related with several sectors such as agriculture, forestry, water management, industry, energy production and transport. A major national operational drought information system is the German Drought Monitor (GDM), launched in 2014. It provides daily soil moisture (SM) simulated...

Populations of rodents such as common vole (Microtus arvalis) can develop impressive soil bioturbation activities in grasslands. These burrowing and nesting activities highly impact soil physicochemical properties as well as vegetation coverage and diversity. Managed grasslands in livestock production regions receive significant amounts of slurry,...

It is a concern whether the effect of soil type on N2O emissions has to be considered for regional mitigation strategies and emission estimates in mountainous areas with inherent spatial heterogeneities of soil type. To date, there were few field experiments which investigated soil type effects on N2O emissions. Thus a 2-year field study was conduc...

The eddy-covariance method provides the most direct estimates for fluxes between ecosystems and the atmosphere. However, dispersive fluxes can occur in the presence of secondary circulations, which can inherently not be captured by such single-tower measurements. In this study, we present options to correct local flux measurements for such large-sc...

The productivity of permanent temperate cut grasslands is mainly driven by weather, soil characteristics, botanical composition and management. To adapt management to climate change, adjusting the cutting dates to reflect earlier onset of growth and expansion of the vegetation period is particularly important. Simulations of cut grassland productiv...

Grasslands in their various forms of appearance characterize the pre-Alpine landscape. Despite the economic value and significant role of plants in grassland carbon and nitrogen cycling, spatially explicit information on grassland biomass are rarely available. This study aims to develop routines to monitor grassland traits at different spatial scal...

Alpine and prealpine grasslands provide various ecosystem services and are hotspots for the storage of soil organic C (SOC) in Central Europe. Yet, information about aggregate-related SOC storage and its controlling factors in alpine and prealpine grassland soils is limited. In this study, the SOC distribution according to the aggregate size classe...

AimsConsequences of climate change and land use intensification on the nitrogen (N) cycle of organic-matter rich grassland soils in the alpine region remain poorly understood. We aimed to identify fates of fertilizer N and to determine the overall N balance of an organic-matter rich grassland in the European alpine region as influenced by intensifi...

Biotic and abiotic controls on carbon storage in aggregates in calcareous alpine and prealpine grassland soils

Short-lived pulses of soil nitrous oxide (N2O) emissions during freeze-thaw periods can dominate annual cumulative N2O fluxes from temperate managed and natural soils. However, the effects of freeze thaw cycles (FTCs) on dinitrogen (N2) emissions, i.e., the dominant terminal product of the denitrification process, and ratios of N2/N2O emissions hav...

The data set contains information on aboveground vegetation traits of > 100 georeferenced locations within ten temperate pre-alpine grassland plots in southern Germany. the grasslands were sampled in April 2018 for the following traits: bulk canopy height; weight of fresh and dry biomass; dry weight percentage of the plant functional types (PFt) no...

Monitoring soil moisture is still a challenge: it varies strongly in space and time and at various scales while conventional sensors typically suffer from small spatial support. With a sensor footprint up to several hectares, cosmic-ray neutron sensing (CRNS) is a modern technology to address that challenge. So far, the CRNS method has typically be...

Sub-Saharan Africa (SSA) is home to approximately ¼ of the global livestock population, which in the last 60 years has increased by factors of 2.5-4 times for cattle, goats and sheep. An important resource for pastoralists, most livestock live in semi-arid and arid environments , where they roam during the day and are kept in enclosures (or bomas)...

Limited information on greenhouse gas emissions from tropical dry forest soils still hinders the assessment of the sources/sinks from this ecosystem and their contribution at global scales. Particularly, rewetting events after the dry season can have a significant effect on soil biogeochemical processes and associated exchange of greenhouse gases....

Nitrous oxide (N2O) emissions are highly episodic in response to nitrogen additions and changes in soil moisture. Automated gas sampling provides the necessary high temporal frequency to capture these emission events in real time, ensuring the development of accurate N2O inventories and effective mitigation strategies to reduce global warming. This...

Isotopic composition of soil‐emitted nitrous oxide (N2O), especially the intramolecular distribution of ¹⁵N in N2O known as site preference (SP), can be used to track the two major N2O emitting soil‐processes nitrification and denitrification. Online analysis of SP in ambient air has been achieved recently, yet those approaches only allowed address...