Vertical Mulching of Trees: Effects on Roots and Water Status

Abstract

We examined the effect of vertical mulching on root growth and xylem water potential of large sugar maples (Acersaccharum) growing in pastures. Root mass in the 35-40 cm depth of undisturbed soil was about 50% that in the 5-10 cm depth, and root mass at the edge of the canopy (7.5 m from the trunk) was about 40% that found at 1 /4 the distance to the edge of the canopy. After three growing seasons, the abundance of roots in perlite-filled vertical mulch channels (0.6 kg/m3) was significantly (P<0.0001) less than in undisturbed soil 1-2 m away from mulch channels (4.4 kg/m3) and in undisturbed soil immediately surrounding mulch channels (3.5 kg/m3). Predawn and midday xylem water potentials, measured in late summer and used as indices of tree health, did not differ between mulched and non-mulched trees. Our results indicated that perlite-filled vertical mulch channels did not affect tree health, and, rather than being utilized as preferred pathways of growth, were avoided by tree roots.