Nutritional changes in trees during drought-induced mortality: A comprehensive meta-analysis and a field study

Area of Science:

• Forest ecology
• Plant physiology
• Nutrient cycling

Background:

• Macronutrients and micronutrients are vital for tree health and ecophysiology.
• The relationship between tree nutrition and drought-induced mortality is not fully understood.
• Understanding this link is crucial for forest management under climate change.

Approach:

• A comprehensive meta-analysis of 11 essential nutrients from 44 publications (493 observations).
• A field study on Pinus sylvestris L. in Switzerland assessing trees with varying drought vitality loss.
• Analysis of factors influencing nutrient status and drought survival, including species, biome, and soil type.

Key Points:

• No consistent decline in overall tree nutritional status was observed preceding mortality.
• Meta-analysis indicated lower leaf potassium (K), iron (Fe), and copper (Cu) with mortality.
• Field study found no causal link between nutrient levels and tree vitality, contrasting meta-analysis findings.
• Discrepancies attributed to experimental designs (seedlings vs. mature trees) and root system development.

Conclusions:

• Nutrient reductions before mortality are more common in young, non-field-grown trees with limited nutrient uptake.
• Leaf nutrients are more sensitive to drought stress; evergreens and Mediterranean forests are more vulnerable.
• Decreased K concentrations may serve as an early warning indicator for declining tree vitality and potential mortality.