Estimating forest net primary production under changing climate: adding pests into the equation

Area of Science:

• Forest ecology
• Ecosystem modeling
• Plant physiology

Background:

• Existing models use constant modifiers for pest impacts on forest net primary production (NPP), failing to account for spatial and temporal variability.
• This leads to likely over or underestimation of pest effects on forest NPP.

Purpose of the Study:

• To review pest impacts on forest NPP and underlying physiological mechanisms.
• To develop a conceptual model of pest impacts across scales (leaf, tree, stand).
• To assess the capacity of current NPP models to capture these physiological processes.

Main Methods:

• Literature review of pest effects on forest NPP and physiological responses.
• Development of a conceptual model integrating leaf, tree, and stand level impacts.
• Comparison of model processes with physiological mechanisms of pest attack.

Main Results:

• Pest outbreaks significantly perturb forest NPP, with varied physiological responses.
• No current NPP model comprehensively captures the range of tree physiological responses to pest attack.
• Existing models primarily developed for other purposes show limited capacity for pest impact modeling.

Conclusions:

• Mechanistic modeling incorporating physiological responses is crucial for accurate forest NPP predictions.
• Future forest growth models must include key physiological processes to adequately capture pest impacts under climate change.
• More empirical data is needed to support the development and validation of these improved models.