Tetiana Svystun
Doctoral student
Understanding the environmental regulation of tree phenology
Author
Summary, in English
In temperate and boreal climates, trees synchronise their annual growth cycles with seasonal changes in daylength and temperature. Understanding how environmental cues regulate tree phenology is important to our ability to capture the potential responses of trees to climate change, with implications for forest productivity.
In this thesis, we demonstrated that different research methods can be applied to study the regulation of tree phenology and that this knowledge can be used to generate climate change impact assessments. The knowledge gaps identified
by summarising recent advances on the molecular regulation of growth cessation and bud set were addressed by modelling. Modelling autumnal bud development showed that both photoperiod and temperature help to predict the
timing of bud set in non-stressful conditions, while additional regulatory mechanisms may be involved under stressful conditions.
The differences in phenological response to environmental signals between populations and provenances were accounted for via the values of model parameters. The provenance specific temperature sum requirements for bud burst for Norway spruce were used to calculate the risk of spring frost damage under current climate conditions and future climate scenario. The timing of bud burst will occur earlier in future and will be associated with an increased risk of
spring frost damage due to the increased frequency and severity of spring frost events. The information on the provenance specific frost risk will facilitate forest management decisions on choosing suitable plant material for regeneration.
The ecosystem model was used to assess the effect of phenology parameterisation on simulating carbon uptake. Model simulations with calibrated phenology parameterization predicted enhanced forest productivity by the end of the century due to earlier timing of bud burst. However, uncertainty remains whether reduced winter chilling may slow down future bud burst advancement and forest productivity increase, highlighting the need for a mechanistic understanding of environmental regulation of dormancy release and bud burst.
Further progress towards a better understanding of regulation of tree phenology can be achieved through integrating molecular and modelling approaches, by incorporating knowledge on molecular pathways of environmental control of
stages of the annual growth cycle into phenological models.
In this thesis, we demonstrated that different research methods can be applied to study the regulation of tree phenology and that this knowledge can be used to generate climate change impact assessments. The knowledge gaps identified
by summarising recent advances on the molecular regulation of growth cessation and bud set were addressed by modelling. Modelling autumnal bud development showed that both photoperiod and temperature help to predict the
timing of bud set in non-stressful conditions, while additional regulatory mechanisms may be involved under stressful conditions.
The differences in phenological response to environmental signals between populations and provenances were accounted for via the values of model parameters. The provenance specific temperature sum requirements for bud burst for Norway spruce were used to calculate the risk of spring frost damage under current climate conditions and future climate scenario. The timing of bud burst will occur earlier in future and will be associated with an increased risk of
spring frost damage due to the increased frequency and severity of spring frost events. The information on the provenance specific frost risk will facilitate forest management decisions on choosing suitable plant material for regeneration.
The ecosystem model was used to assess the effect of phenology parameterisation on simulating carbon uptake. Model simulations with calibrated phenology parameterization predicted enhanced forest productivity by the end of the century due to earlier timing of bud burst. However, uncertainty remains whether reduced winter chilling may slow down future bud burst advancement and forest productivity increase, highlighting the need for a mechanistic understanding of environmental regulation of dormancy release and bud burst.
Further progress towards a better understanding of regulation of tree phenology can be achieved through integrating molecular and modelling approaches, by incorporating knowledge on molecular pathways of environmental control of
stages of the annual growth cycle into phenological models.
Department/s
- Dept of Physical Geography and Ecosystem Science
- BECC: Biodiversity and Ecosystem services in a Changing Climate
Publishing year
2021
Language
English
Full text
Document type
Dissertation
Publisher
Lund University
Topic
- Forest Science
- Ecology
Keywords
- Phenological events, environmental cues, temperature response, phenological modelling, frost risk, gross primary production, climate change impact
Status
Published
Supervisor
- Anna Maria Jönsson
- Rishikesh P. Bhalerao
ISBN/ISSN/Other
- ISBN: 978-91-89187-05-4
- ISBN: 978-91-89187-06-1
Defence date
16 June 2021
Defence time
10:00
Defence place
Hörsal 229 (Pangea) Join via zoom: https://lu-se.zoom.us/meeting/register/u50vc-6trD0vHdL55NSSPgu6UyyLBJtLUU1Z
Opponent
- Susanne S. Renner (Professor)