Root distribution chronosequence of a dense dwarfed jujube plantation in the semiarid hilly region of the Chinese Loess Plateau

Abstract

Dense jujube (Ziziphus jujube Mill. CV. Lizao) plantations with a spacing of 2 m between trees and 3 m between tree rows have been established in the semiarid hilly region of the Chinese Loess Plateau since 1999. Our objective was to assess differences in the vertical and horizontal root distribution with stand age based on a trench wall analysis of the roots. The stands were 4, 8, and 11 years old. We investigated three root diameter classes for each stand, which consisted of fine (< 1 mm), medium (1–3 mm), and coarse (> 3 mm) roots. Our main findings were as follows. (1) All diameter classes of root intersects increased significantly with stand age (P < 0.01). However, the proportion of the three diameter classes in the total roots remained about the same, regardless of stand age. (2) Root intersects decreased significantly with soil depth (P < 0.001). (3) There were no significant differences in root intersects with distance from the trunk (P > 0.05) in this dense planting pattern. These root distribution patterns may enhance our understanding of the dense jujube plantation belowground root ecology and provide a basis for jujube plantation management practices in this semiarid hilly region.