<figure><img src="image_1.png" /></figure>

HAL
open science

# Spring leaf phenology sensitivity to climate change considering organ's temperature and morphological traits

Laëtitia de Felix, Marc Peaucelle, Jérôme Ogée

► To cite this version:

Laëtitia de Felix, Marc Peaucelle, Jérôme Ogée. Spring leaf phenology sensitivity to climate change considering organ's temperature and morphological traits. Novel constraints on the coupling between the water and carbon cycles - Mary Anning conference, Jun 2025, Bordeaux, France. 2025. hal-05122401

HAL Id: hal-05122401

https://hal.science/hal-05122401v1

Submitted on 20 Jun 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_2.png" /></figure>

Open licence - etalab
# Spring leaf phenology sensitivity to climate change considering organ's temperature and morphological traits

INRAO

<figure><img src="image_3.png" /></figure>

Laëtitia de Felix, Marc Peaucelle, Jérôme Ogée
ISPA, INRAe Nouvelle-Aquitaine Bordeaux, France

<figure><img src="image_4.png" /></figure>

European Research Council
Established by the European Commission

<figure><img src="image_5.png" /></figure>

Funded by the European Union (ERC, LEAFPACE, 101117001). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them.

## CONTEXT

### 1. Context

<figure><img src="image_6.png" /></figure>

Phenology stages and their abiotic factors

<figure><img src="image_7.png" /></figure>

Climate change

Shifts in phenology

<figure><img src="image_8.png" /></figure>

Large scale impacts on biogeochemical cycles

<figure><img src="image_9.png" /></figure>

VOCs

<figure><img src="image_10.png" /></figure>

Water

<figure><img src="image_11.png" /></figure>

Surface energy budget

<figure><img src="image_12.png" /></figure>

Carbon

Especially for spring phenology, budburst tend to occur earlier because of climate change.

### 2. Problematic

An increasing gap between observations and simulations of spring phenology with increasing temperature

<figure><img src="image_13.png" /></figure>

Variations in observed and simulated budburst date (BBD; squares) or leaf unfolding date (LUD; dots) with mean temperature from January to May for deciduous broadleaf trees (DBT) (Li et al., 2022)

<figure><img src="image_14.png" /></figure>

Possible reason

Vegetation models use macroclimate air temperatures

<figure><img src="image_15.png" /></figure>

<figure><img src="image_16.png" /></figure>

Bud's internal temperature
Where physiological processes occur

<figure><img src="image_17.png" /></figure>

## HYPOTHESIS

Using organ temperature instead of air temperature would improve accuracy of phenological models

## MATERIAL AND METHOD

12 species have been selected for their representativity in Europe and diversity of bud and foliar morphological traits.

<figure><img src="image_18.png" /></figure>

### Bud's temperature

Bud temperature monitored with thermocouples

<figure><img src="image_19.png" /></figure>

### Microclimate

<figure><img src="image_20.png" /></figure>

### Buds' morphological traits

<figure><img src="image_21.png" /></figure>

<figure><img src="image_22.png" /></figure>

<figure><img src="image_23.png" /></figure>

## OBJECTIVES

- Improve accuracy if phenological models

- To better account for factors like day length or radiation load

- Investigate interspecific differences in terms of temperature by measuring organ temperature and characterize organs' morphological traits.

## PRELIMINARY RESULTS

### Morphological traits

<table><thead><tr><th>Species</th><th>Fresh weight (g)</th><th>Dry weight (g)</th><th>Width (mm)</th><th>Length (mm)</th><th>Height (mm)</th></tr></thead><tbody><tr><td>Alnus glutinosa</td><td>0.11 ± 0.02</td><td>0.06 ± 0.01</td><td>4.9 ± 0.5</td><td>5 ± 0.5</td><td>11.1 ± 1.2</td></tr><tr><td>Fraxinus excelsior</td><td>0.1 ± 0.03</td><td>0.05 ± 0.01</td><td>6.3 ± 1.3</td><td>7 ± 0.2</td><td>6.2 ± 0.7</td></tr></tbody></table>

<figure><img src="image_24.png" /></figure>

Average reflectance on the visible and near-infrared spectra

<figure><img src="image_25.png" /><figcaption>Alnus glutinosa</figcaption></figure>

<figure><img src="image_26.png" /><figcaption>Fraxinus excelsior</figcaption></figure>

Buds' transect pictures by using the AxioZoom

### Statistical links?

### Relationship to incident shortwave radiations

<figure><img src="image_27.png" /></figure>

Relationship between bud-air temperature difference (ΔT) and incident solar radiation in February 2025 for two species

### Bud - air temperatures

<figure><img src="image_28.png" /></figure>

Mean diurnal cycle of bud-air temperature difference (ΔT) and incident solar radiation in February 2025 for two species

The results suggest that bud-air temperature difference and its response to incident shortwave radiation depends on morphological traits, particularly bud reflectance and bud size.

## PERSPECTIVES

- Explore with statistical modelling the relationships between bud morphological traits and bud-air temperature differences

- Evaluate energy budget modelling and its ability to retrieve bud temperature from microclimate data

- Evaluate the impact of bud-air temperature differences for predicting bud burst dates