Nonstructural carbohydrate dynamics' relationship to leaf development under varying environments.

Area of Science:

• Forest ecology
• Plant physiology
• Global change biology

Background:

• Leaf-out timing in temperate forests is a critical spring event influenced by global change.
• The precise mechanisms linking phenological variation to environmental cues remain unclear.
• Nonstructural carbohydrate (NSC) availability is hypothesized to play a key role.

Purpose of the Study:

• To investigate the relationship between Nonstructural Carbohydrates (NSCs) and leaf-out timing in northern red oak (Quercus rubra).
• To examine the impact of temperature, photoperiod, and genotype on NSC dynamics and phenological variation.
• To determine if NSCs can serve as a molecular clock for triggering budburst.

Main Methods:

• Branch cuttings of northern red oak (Quercus rubra) were used to measure NSCs during bud development.
• Branches were subjected to a factorial experiment with varying temperatures and photoperiods across eight genotypes.
• Leaf-out timing and NSC concentrations were monitored across different phenophases and experimental conditions.

Main Results:

• Despite significant variations in leaf-out timing across treatments, NSC concentrations remained consistent throughout phenophases.
• Moderate and hot temperature treatments reached similar NSC levels and phenophases at the same growing degree days (GDD), though 20 days apart.
• The cold treatment accumulated only half the GDD compared to the other treatments, indicating temperature's influence on GDD accumulation.

Conclusions:

• NSC patterns are tightly coordinated with leaf-out timing in northern red oak.
• NSCs may function as an internal molecular clock, signaling the progression of time to initiate leaf development.
• Understanding the link between NSCs and budburst is vital for enhancing predictions of forest phenology in a changing climate.