A5030354807- Plant Water Relations and Carbon Dynamics
- Tree-ring climate responses
- Forest ecology and management
- Plant responses to elevated CO2
- Hydrology and Watershed Management Studies
- Ecology and Vegetation Dynamics Studies
- Logic, programming, and type systems
- Plant responses to water stress
- Photosynthetic Processes and Mechanisms
- Formal Methods in Verification
- Plant nutrient uptake and metabolism
- Tree Root and Stability Studies
- Soil Carbon and Nitrogen Dynamics
- Software Engineering Research
- Horticultural and Viticultural Research
- Soil and Unsaturated Flow
- Leaf Properties and Growth Measurement
- Advanced Software Engineering Methodologies
- Cryospheric studies and observations
- Urban Heat Island Mitigation
- Forest Ecology and Biodiversity Studies
- Lichen and fungal ecology
- Software Testing and Debugging Techniques
- Atmospheric and Environmental Gas Dynamics
- Fire effects on ecosystems
University of Helsinki
2016-2024
Istanbul Aydın University
2023
University of Zurich
2011-2021
University of Edinburgh
2014-2020
Arizona State University
2020
Hebrew University of Jerusalem
2020
Helsinki Institute of Physics
2016
ETH Zurich
2007-2016
Board of the Swiss Federal Institutes of Technology
2016
Université de Rennes
2015
Summary Accumulating evidence highlights increased mortality risks for trees during severe drought, particularly under warmer temperatures and increasing vapour pressure deficit ( VPD ). Resulting forest die‐off events have consequences ecosystem services, biophysical biogeochemical land–atmosphere processes. Despite advances in monitoring, modelling experimental studies of the causes tree death from individual to global scale, a general mechanistic understanding realistic predictions...
Abstract Heatwaves exert disproportionately strong and sometimes irreversible impacts on forest ecosystems. These remain poorly understood at the tree species level across large spatial scales. Here, we investigate effects of record-breaking 2018 European heatwave growth water status using a collection high-temporal resolution dendrometer data from 21 53 sites. Relative to two preceding years, annual stem was not consistently reduced by but stems experienced twice temporary shrinkage due...
Accurate modelling of drought-induced mortality is challenging. A steady-state model presented integrating xylem and phloem transport, leaf-level gas exchange plant carbohydrate consumption during drought development. Bayesian analysis parameter uncertainty based on expert knowledge a literature review carried out. The tested by combining six data compilations covering 170 species using information sensitivities conductivity, stomatal conductance leaf turgor to water potential. possible...
Summary Photosynthetic rate is concurrently limited by stomatal limitations and nonstomatal (NSLs). However, the controls on NSLs to photosynthesis their coordination with control different timescales remain poorly understood. According a recent optimization hypothesis, depend leaf osmotic or water status are coordinated so as maximize photosynthesis. Drought notching experiments were conducted Pinus sylvestris , Picea abies Betula Pendula Populus tremula seedlings in glasshouse conditions...
The pull of water from the soil to leaves causes in transpiration stream be under negative pressure decreasing potential below zero. osmotic concentration also contributes decrease leaf but with much lesser extent. Thus surface tension force is approximately balanced by a induced resulting concavely curved water-air interfaces leaves. lowered reduction equilibrium vapour internal (sub-stomatal/intercellular) cavities relation that over zero, i.e. flat surface. dissolved CO2, thus enhancing...
Substantial uncertainty surrounds our knowledge of tree stem growth, with some the most basic questions, such as when radial growth occurs through daily cycle, still unanswered. We employed high-resolution point dendrometers, sap flow sensors, and developed theory statistical approaches, to devise a novel method separating irreversible from elastic tension-driven osmotically driven changes in bark water content. tested this using data five case study species. Experimental manipulations,...
Summary Tree responses to altered water availability range from immediate (e.g. stomatal regulation) delayed crown size adjustment). The interplay of the different response times and processes, their effects on long‐term whole‐tree performance, however, is hardly understood. Here we investigated legacy structures functions mature Scots pine in a dry inner‐Alpine Swiss valley after stopping an 11‐yr lasting irrigation treatment. Measured ecophysiological time series were analysed interpreted...
Understanding physiological processes involved in drought-induced mortality is important for predicting the future of forests and modelling carbon water cycles. Recent research has highlighted variable risks starvation hydraulic failure drought-exposed trees. However, little known about specific responses leaves supporting twigs, despite their critical role balancing acquisition loss. Comparing healthy (non-defoliated) unhealthy (defoliated) Scots pine at same site, we measured variables...
Phloem osmolality and its components are involved in basic cell metabolism, growth, various physiological processes including the ability of living cells to withstand drought frost. Osmolality sugar composition responses environmental stresses have been extensively studied for leaves, but less secondary phloem plant stems branches. Leaf osmotic concentration share pinitol raffinose among soluble sugars increase with increasing or cold stress, is adjusted osmoregulation. We hypothesize that...
ABSTRACT Understanding ecosystem water fluxes has gained increasing attention, as climate scenarios predict a drier environment for many parts of the world. Evaporative enrichment 18 O (Δ O) leaf and subsequent plant organic matter can be used to characterize environmental physiological factors that control evaporation, based on recently established mechanistic model. In Pinus sylvestris forest, we measured dynamics oxygen isotopic composition ( δ every 6 h 4 d in atmospheric vapour, xylem...
Abstract Starch and soluble sugars are the major photosynthetic products, their carbon isotope signatures reflect external versus internal limitations of CO 2 fixation. There has been recent renewed interest in composition carbohydrates, mainly for use flux partitioning studies at ecosystem level. The obstacle to carbohydrates such lack an acknowledged method isolate starch isotopic measurements. We here report on comparison evaluation existing methods (acid enzymatic hydrolysis starch;...
Transpiration from the Amazon rainforest generates an essential water source at a global and local scale. However, changes in function with climate change can disrupt this process, causing significant reductions precipitation across Amazonia, potentially We report only study of forest transpiration following long-term (>10 year) experimental drought treatment Amazonian forest. After 15 years receiving half normal rainfall, drought-related tree mortality caused total to decrease by 30%....
Summary Experimental evidence that nonstomatal limitations to photosynthesis (NSLs) correlate with leaf sugar and/or water status suggests the possibility stomata adjust maximise through a trade‐off between CO 2 supply and NSLs, potentially involving source–sink interactions. However, mechanisms regulating NSLs sink strength, as well their implications for stomatal control, remain uncertain. We used an analytically solvable model explore optimal control under alternative hypotheses source...
Future climate will be characterized by an increase in frequency and duration of drought warming that exacerbates atmospheric evaporative demand. How trees acclimate to long-term soil moisture changes whether these alter trees' sensitivity short-term (day months) variations vapor pressure deficit (VPD) is largely unknown. Leaf gas exchange measurements were performed within a (17 years) irrigation experiment drought-prone Scots pine-dominated forest one Switzerland's driest areas on...
Sunflecks are transient patches of direct radiation that provide a substantial proportion the daily irradiance to leaves in lower canopy. In this position, faster photosynthetic induction would allow for higher sunfleck-use efficiency, as is commonly reported literature. Yet, when sunflecks too few and far between, it may be more beneficial shade prioritize efficient photosynthesis under shade. We investigated temporal dynamics induction, recovery shade, stomatal movement during sunfleck,...
Increasing drought intensity, duration and frequency worldwide challenges tree health. In addition to the importance of resistance, post-drought recovery capacity is a vital determinant in growth survival. However, trees recover from different types stress remains largely unquantified. this study, we applied three treatments (short-term drought, long-term repeated drought) well-watered control 3-year-old silver birch (Betula pendula) saplings growing greenhouse. Ecophysiological traits...
Laser spectroscopy-based gas isotope analysers (LSIA) are cheaper in acquisition and maintenance but still lack the accuracy precision available through ratio mass spectrometry (IRMS). One of applications where LSIA particularly advantageous online measurements that follow release over time. This is even more case labelling experiments, requirements regarding lower. Yet, experiments implement such setups remain relatively rare.Here, we present a simple, low-cost setup conducts automated...
Positive sap pressures are produced in the xylem of birch trees boreal conditions during time between thawing soil and bud break. During this period, embolisms accumulated wintertime refilled with water. The mechanism for pressurization its environmental drivers not well known. We measured flow, pressure, osmotic concentration, whole stem diameter changes, root non-structural carbohydrate concentrations, along meteorological at two sites Finland after pressurisation period. diurnal dynamics...