Coarse root biomass and architecture of hybrid aspen 'Crandon' (Populus alba L. × P. grandidenta Michx.) grown in an agroforestry system in central Iowa, USA

• Published in: Journal of sustainable forestry Vol. 38; no. 1; pp. 18 - 30
• Main Authors: Headlee, William L., Zalesny, Ronald S., Hall, Richard B.
• Format: Journal Article
• Language: English
• Published: Philadelphia Taylor & Francis 02.01.2019; Taylor & Francis Ltd
• Subjects: Agroforestry; Architecture; Biomass; Biomass allocation; Excavation; fertilizer; Fertilizers; Forestry; pipe theory; root geometry; Roots; Sustainability; Topography; Trees
• ISSN: 1054-9811; 1540-756X
• DOI: 10.1080/10549811.2018.1491861

In this study, we evaluated 'Crandon' coarse root biomass and architecture grown at different topographic positions and fertilizer rates. Complete excavations were conducted on a subset of trees after the first growing season and showed that root biomass was strongly related to stem biomass (R 2 = 0.93), but not topographic position or fertilizer rate. After the third growing season, subsamples of roots were collected from another subset of trees and showed coarse root architecture variables to be strongly related to several metrics of the tree and root size (R 2 = 0.61 to 0.82), while also differing by topographic position. Equations relating root biomass to stem biomass were derived from both methodologies (complete excavation v. subsampling for architecture measurements), and comparison of the equations indicated no difference in slopes (p = 0.59) or intercepts (p = 0.90), although the subsampling approach had a weaker model fit. Our results suggest 'Crandon' roots (i) adhere to strong allometric relationships with stem biomass, (ii) alter their architecture within the constraints of this allometric relationship according to site conditions, and (iii) can be subsampled to estimate root biomass from root architecture parameters with similar accuracy (but less precision) compared to complete excavations.