%0 Journal Article %A Wei ZHU %A Li-Xuan YU %A De-Hai ZHAO %A Li-Ming JIA %T Architectural analysis of root systems of mature trees in sandy loam soils using the root development classification %D 2019 %R 10.17521/cjpe.2018.0269 %J Chinese Journal of Plant Ecology %P 119-130 %V 43 %N 2 %X <i>Aims</i>

Understanding the differences in root architectural strategies among the species and the differences in morphological characteristics among different root orders will facilitate our understanding root growth and development strategies, and thus provide a basis for predicting and modeling the root systems for mature trees. In this study, we analyzed the morphological characteristics and topological relationships for the root systems of two Populus tomentosa trees and one Robinia pseudoacacia tree.

<i>Methods</i>

A method combining both excavation and analysis was applied to extract and quantify root architectural characteristics of the three root systems. The morphological characteristics such as root basal diameter, root length, link length, and root number of different root orders were described using the developmental analysis method of Rose (1983), and their topological relationships were analyzed.

<i>Important findings</i>

1) The modified topological indices qa and qb were close to 0, and the topological index TI was close to 0.5 for all three root systems, indicating their dichotomous structure. The depth and width of the systems ranged from 5.7 to 6.4 m and from 7.6 to 13.5 m, respectively. Root grafts occurred in the same species. 2) The root systems could have the seventh or eighth order roots. The basal root diameter and root length significantly decreased with increasing root order. The first order roots had 5.79-36.92 times the basal diameter and 1.45-9.11 times the length of higher order roots. With increasing root order, the root number increased, and reached a maximum value for the third order roots, and then decreased. 3) In roots of each of the first three orders, the link length varied little from the root base towards its tip, indicating that the child roots were distributed evenly on their parent roots and thus help trees absorb soil resources more efficiently. 4) The regression of basal diameters of child roots on basal diameters of their mother roots showed that the smallest slope for the first order roots (average slope 0.15) and no big difference in the slope between the second and third order roots (0.34 versus 0.35). This suggested that the first order roots developed their own diameter first for anchoring and supporting the tree, while the second and third order roots developed their child roots to facilitate nutrient uptake from the soil. 5) The regression of root length on root basal diameter suggested that the slope increased from 10.46 to 90.43 with increasing root order, which implies that the higher order roots tended to develop their length to explore resources and expand their space.

%U https://www.plant-ecology.com/EN/10.17521/cjpe.2018.0269