TOLERANCE OF TREE ROOTS TO WATERLOGGING

Abstract

A study is presented of the growth of rooted cuttings of Lodgepole pine and Sitka spruce into waterlogged soil. Lodgepole pine roots penetrated to depths of 20 cm at 10°C in soil devoid of oxygen, whereas Sitka spruce made only shallow growth into the water‐table. The growth rate of the pine roots decreased with depth below the water‐table and penetration was greater at 10 °C than at 20 °C. Large gas‐filled cavities were found in the stele of the pine roots that penetrated the water‐table but were absent from the spruce. When pine roots were allowed to grow into a water‐table for 2 cm. and were subsequently inundated to a depth of 10 cm, root tip survival was much better than where non‐acclimatized roots were flooded.The results suggest that the deeper penetration of waterlogged soil by Lodgepole pine than Sitka spruce is due to internal oxygen transport in the pine roots; oxygen transport and other possible mechanisms for growth and survival of roots in waterlogged soil are discussed.