Poplar root biomass (compatible total-biomass system)

D

Diameter at breast height (1.3 m), cm

H

Total tree height, m

Final root model of the compatible system, fitted on trees with root samples (n from Table 1). Compatible total-biomass system (aboveground fitted independently, total and root fitted jointly by simultaneous estimation; weighted nonlinear least squares). Total = aboveground + root. The paper lists the sample as stratified random felled trees across eight diameter classes (4-32 cm) from 2022-2023; the reported minimum and maximum DBH and height are for all sampled trees of the species (Table 1). Root biomass was measured on a subset only (whole-root excavation: root collar, coarse roots, fine roots), so root and total fit ranges are not given beyond the full sample. No back-transform factor (nonlinear fit). The paper also gives aboveground-component (stem, crown, wood, bark, branch, foliage) systems (Tables 17-39), not added here. R² is the evaluation row marked * (the 36 trees with measured roots, matching n_trees; the paper's Discussion cites these starred values as the root-model R²); the unstarred row (0.8239) is evaluated over all sampled trees, most of which have no measured roots.