Effects of soil freezing on fine roots in a northern hardwood forest (original) (raw)

We reduced early winter snowpack in four experimental plots at the Hubbard Brook Experimental Forest in New Hamphire for 2 years to examine the mechanisms of root injury associated with soil freezing. Three lines of evidence suggested that direct cellular damage, rather than physical damage associated with frost heaving, was the principal mechanism of root injury: (i) decreases in root vitality were not greater on sites with more frost heaving, (ii) in situ freezing damage was confined to first- and second-order roots in the organic horizons rather than entire root systems, and (iii) tensile strength of fine roots was not significantly compromised by experimental stretching to simulate ice lens formation. Although significant differences in the intensity of soil freezing (depth, rate, and minimum temperature) were observed across the plots, no clear effects of soil freezing intensity on root injury were observed. Snow manipulation had no effect on mycorrhizal colonization of sugar m...