Data from: Shift from an extensive to an intensive root nutrient-acquisition mode with stand development of three Pinus species

Plant roots employ diverse strategies to acquire soil nutrients, including
direct nutrient uptake through absorptive fine roots and root hairs,
scavenging nutrients by forming symbioses with mycorrhizal fungi, and
mining nutrients by releasing root exudates. However, whether these three
strategies are differently coordinated among phylogenetically
closely-related tree species and how this coordination shifts with stand
development remains largely unclear. To fill these knowledge
gaps, we measured 13 root morphological, architectural, physiological and
mycorrhizal traits tightly related to nutrient-acquisition of
three Pinus species (P. sylvestris var. mongolica, P. densiflora
and P. tabuliformis) at young (20-year-old) and mature (50-year-old)
stages planted in nutrient-impoverished sandy soils, in Northeast
China. We found that young trees had thinner absorptive fine
roots and a higher specific root length than mature trees across
three Pinus species, indicating that roots become morphologically
less efficient in “do it yourself” scavenging nutrients during stand
development. Moreover, young stands had greater root length density and
root area index, and mature stands had faster root-exudation rates,
suggesting that young stands rely more on expanding soil volumes to
scavenge nutrients and mature stands depend more on root exudation to
‘mine’ nutrients. The three Pinus species exhibited different
nutrient-acquisition strategies at the mature stage; P. densiflora had
higher root length density and root area index, and the other two Pinus
species had greater ectomycorrhizal colonization rates. Synthesis. Our
findings highlight that phylogenetically closely-related tree species may
exhibit different nutrient-acquisition strategies, and suggest a shift
from an extensive nutrient-acquisition mode depending more on absorptive
fine roots to an intensive nutrient-acquisition mode relying more on root
exudation during stand development.