Root traits reveal safety and efficiency differences in grasses and shrubs exposed to different fire regimes

Roots are key components of terrestrial ecosystems, yet little is known about how root structure and function vary across a broad range of species, functional groups, and ecological gradients in situ.

We assessed how woody and grass root anatomical traits vary among soil depths and different fire frequencies to better understand the water-use strategies exhibited by these two functional groups in tallgrass prairie experiencing woody encroachment. Specifically, we asked: (1) Do root anatomical traits differ with fire frequency or soil depth? (2) Do relationships between anatomical traits that confer hydraulic safety versus efficiency vary by fire frequency or soil depth? (3) Is root anatomy associated with integrative root traits (e.g., root diameter, specific root length (SRL), and root biomass)? (4) When scaled by root biomass, do root water-use traits impact the capacity for water uptake?

We collected grass and woody roots from 10, 30, and 50 cm deep soil in areas burned every 1...