PhD Position: WHAT ROLE DOES THE MICROCLIMATE PLAYS ON THE SENSITIVITY OF LEAF PHENOLOGY TO WARMING AND CONSEQUENCES ON FOREST RESILIENCE?

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PhD Position: WHAT ROLE DOES THE MICROCLIMATE PLAYS ON THE SENSITIVITY OF LEAF PHENOLOGY TO WARMING AND CONSEQUENCES ON FOREST RESILIENCE?

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Offer DescriptionYou will be welcomed in the unit Interactions Sol Plante ATmosphère (UMR 1391 ISPA, Bordeaux, France) for a 3 years PhD position in the context of the ERC project LEAFPACE: Will leaf phenology keep pace with climate warming?Project description:Leaf phenology, the study of the drivers and dynamics of leaf budburst, unfolding, maturation and senescence, controls carbon, water and energy exchanges between forests and the atmosphere. Current approaches establish an empirical link between leaf phenology and standardised air temperature (the macroclimate), and fail to capture the true conditions sensed by trees (the microclimate). This results in a biased interpretation of the role of other factors, such as light, as well as the response of trees to climate warming, and leads to major uncertainties in the projections of forest dynamics and resilience.The aim of this thesis project is to fill this gap by quantifying the role of microclimate on leaf phenology. By combining in situ observations, controlled experiments and modelling, this project will 1) quantify the microclimatic control of leaf phenology and clearly disentangle the factors that govern it, 2) develop new phenology models based on bud and leaf temperature and 3) reassess the sensitivity of phenology to past and future climate across scales.Context:The phenology of leaves, i.e. their development, growth and senescence, has a direct influence on forest productivity and biomass. It also influences local weather conditions and long-term climate through transpiration, albedo and carbon storage (Peñuelas et al. 2009). The rapidity of current climate change is leading to major disruptions in phenological cycles on a global scale, increasing the risks (e.g. of frost or spring drought) faced by trees that were adapted to past environmental conditions (Peaucelle et al. 2019). Despite centuries of research and observations, a thorough fundamental understanding of the environmental factors governing leaf phenology is still lacking. The poor representation of phenology in models of the terrestrial biosphere is considered to be one of the main uncertainties in carbon cycle estimates and future climate predictions.Temperature is recognised as the main driver of leaf phenology in extra-tropical ecosystems. For this reason, phenology models generally rely on metrics based on the air temperature preceding phenological events, often in the form of a sum of degree-days. Numerous variants of phenological models have been proposed to describe budburst, growth and leaf senescence, including the duration of sunshine or photoperiod as another climatic variable, but with often limited success compared with a model based solely on growing degree-days. One of the reasons for these limitations is that today’s climate is changing too quickly, so that models based on past and relatively ‘stable’ climatic conditions are not very good at predicting phenology in recent years, which have seen a number of record-breaking climatic extremes. Another reason is that these models are based on the average air temperature of a geographical location, also known as the ‘macro-climatic’ temperature, which does not allow us to capture the spatio-temporal variability in the landscape of organ temperatures (buds, leaves), and therefore phenology.This thesis aims to study in greater detail the biophysical processes, and in particular the thermal processes, that control leaf phenology. Recent studies have highlighted the key role of solar radiation and biophysical properties such as bud and leaf albedo in spring phenology (Vitasse et al., 2021; Peaucelle et al. 2022) as well as in physiological activity, the latter being identified as a potential driver of leaf senescence. This suggests that the temperature conditions perceived by tree buds and leaves (i.e. the microclimate) are of key importance for understanding and accurately simulating leaf phenology and their response to future environmental conditions.Objectives:The general aim of this thesis project is to study the role of microclimate on leaf phenology in forests. More specifically, you will focus on European deciduous forest species for which microclimatic processes due to seasonal canopy closure are particularly pronounced (De Frenne et al. 2021), and you will seek to test the following two hypotheses:(H1) The energy balance of buds or leaves is essential for disentangling the effects of temperature, radiation and photoperiod on leaf phenology.(H2) Photoperiod-sensitive deciduous species perceive light through the photosynthetic tissues of the buds or bark.Method:To meet these objectives, you will be required to develop a multidisciplinary approach combining experiments under controlled conditions, field observations, data analysis and process modelling through 3 tasks:1) Analyse the relationships between organ temperature (buds, leaves), phenology and environmental conditions. For this task, you will be required to carry out several controlled experiments (e.g. temperature, sunshine, irrigation, fertilisation) and to install sensors (e.g. thermal cameras) and take measurements (e.g. functional traits, photosynthesis) in the field.2) Develop and calibrate a phenological model that considers bud and leaf temperature and the effect of microclimate. This task will involve evaluating existing models and developing a new phenology model based on the results of task 1.3) Reassess the sensitivity of past and future leaf phenology to climatic conditions. The aim of this task will be to re-analyse past phenology data and make future predictions on several spatial and temporal scales using the phenology model developed in task 2. This new model could be coupled with other processes in order to quantify the role of phenology on the associated biogeochemical cycles in the context of global change.References:De Frenne P, Lenoir J, Luoto M, et al (2021) Forest microclimates and climate change: Importance, drivers and future research agenda. Global Change Biology 27:2279-2297. .Peaucelle M, Peñuelas J, Verbeeck H (2022) Accurate phenology analyses require bud traits and energy budgets. Nature Plants 8:915- 922. .Peaucelle M, Janssens IA, Stocker BD, Descals Ferrando A, Fu YH, Molowny-Horas R, Ciais P, Peñuelas J (2019) Spatial variance of spring phenology in temperate deciduous forests is constrained by background climatic conditions. Nature communications, 10, 5388.Peñuelas J, Rutishauser T, Filella I (2009) Ecology. Phenology feedbacks on climate change. Science (New York, N.Y.), 324, 887-888.Vitasse Y, Baumgarten F, Zohner CM, et al (2021) Impact of microclimatic conditions and resource availability on spring and autumn phenology of temperate tree seedlings. New Phytologist 232:537-550. .About INRAE:The French National Research Institute for Agriculture, Food, and the Environment (INRAE) is a public research establishment. It is a community of 12,000 people with more than 200 research units and 42 experimental units located throughout France. The institute is among the world leaders in agricultural and food sciences, in plant and animal sciences, and is 11th in the world in ecology and environment. INRAE’s main goal is to be a key player in the transitions necessary to address major global challenges. In the face of the increase in population, climate change, scarcity of resources and decline in biodiversity, the institute develops solutions for multiperformance agriculture, high quality food and sustainable management of resources and ecosystems.RequirementsResearch Field Environmental science » Ecology Education Level Master Degree or equivalentSkills/QualificationsRecommended training: Master 2 or equivalent in environmental sciences.Knowledge required: Computer programming (R, Python), environmental data analysis.Appreciated experience: Theoretical or experimental research.Skills sought: Ability to work in a team, to write (scientific articles) and to express oneself (scientific conferences) in English.Keen interest in forest fieldwork, experimentation and modeling.Languages ENGLISH Level GoodAdditional InformationBenefitsBy joining our teams, you benefit from (depending on the type of contract):– until 30 days of annual leave + 15 days “Reduction of Working Time” (for a full time);
– : CESU childcare, leisure services;
– skills development systems: , ;
– : advice and listening, social assistance and loans;
– : holiday vouchers, accommodation at preferential rates;
– ;
– collective catering.Selection process30 min interviewAdditional commentsThis PhD position takes place in the context of the ERC LEAFPACE project. The candidate will collaborate with a team of 5 researchers on this project in addition to several national and international collaborations. Website for additional job detailsWork Location(s)Number of offers available 1 Company/Institute INRAE Country France State/Province Nouvelle Acquitaine City Villenave d’Ornon Postal Code 33140 Street 71 avenue Edouard Bourlaux GeofieldWhere to apply E-mailmarc.peaucelle@inrae.frContact CityVillenave d’Ornon WebsiteStreet71 avenue Edouard Bourlaux Postal Code33882STATUS: EXPIRED

Expected salary

Location

Villenave-d’Ornon, Gironde

Job date

Sun, 14 Apr 2024 07:53:52 GMT

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