Root System Morphology Influences Lateral Stability of Swietenia mahagoni

Abstract

Propagation containers modify root systems, which affect post-planting anchorage in reforestation efforts, but little is known about larger-sized trees typical in urban landscapes. The main goal of this study was to determine the role of root morphology on postplanting anchorage and growth on Swietenia mahagoni (L.) Jacq., a common landscape tree in warm climates. Two propagation container types, two larger container types, and root pruning were used to impose various root morphologies inside root balls. Anchorage was evaluated by winching trees at two bending stresses to simulate wind events. Interaction between propagation container type and root pruning when the liner was shifted into 3.8 L containers prevented either from consistently influencing anchorage. Trunk tilt (i.e., instability) immediately following pulling was greatest for trees with the most root CSA deflected by the 9.5 L container; trees with straighter main roots in the root ball were better anchored. Researchers found seven root attributes associated with trunk tilt during winching tests that evaluated anchorage. Results show that straight roots in the root ball were associated with stable trees after planting into field soil.