Seedling traits predict drought-induced mortality linked to diversity loss.

Area of Science:

• Ecology
• Plant Biology
• Climate Change Science

Background:

• Trait-based approaches are vital for predicting climate change effects on ecosystems.
• Existing research often overlooks the significance of root traits and seedling vulnerability in changing climates.
• Understanding plant traits is crucial for predicting ecological shifts.

Purpose of the Study:

• To investigate the relationship between plant traits, seedling mortality, and community changes under drought conditions.
• To identify critical seedling and root traits that influence survival during winter drought.
• To assess the role of constitutive variation versus adaptive plasticity in plant responses to drought.

Main Methods:

• A field experiment was conducted in an annual grassland during a dry winter (2017-2018).
• Comprised watered and unwatered plots to simulate drought conditions.
• Measured seedling and adult plant traits, mortality, and growth.

Main Results:

• Seedling mortality was higher, and growth was lower in unwatered plots.
• Higher seedling mortality was associated with shorter seedling roots, small seeds, high specific leaf area (SLA), and tall seedlings.
• Constitutive seedling root length was the primary predictor of seedling survival under drought.
• Adult traits showed weak correlations with seedling traits and mortality; adaptive plasticity was not observed.

Conclusions:

• Seedling root length is a critical trait for predicting survival in drought-prone environments.
• Observed declines in native diversity under drought may be linked to species with specific trait combinations.
• Focusing on seedling and root traits is essential for robust ecological predictions under climate change.