Data from: Genotypic traits and tradeoffs of fast growth in silver birch, a pioneer tree

Fast-growing and slow-growing plant species are suggested to show
integrated economics spectrums and the tradeoffs of fast growth are
predicted to emerge as susceptibility to herbivory and resource
competition. We tested if these predictions also hold for fast-growing and
slow-growing genotypes within a silver birch, Betula pendula population.
We exposed cloned saplings of 17 genotypes with slow, medium or fast
height growth to reduced insect herbivory, using an insecticide, and to
increasing resource competition, using naturally varying field plot grass
cover. We measured shoot and root growth, ectomycorrhizal (EM) fungal
production using ergosterol analysis and soil N transfer to leaves using
15N-labelled pulse of NH4+. We found that fast-growing genotypes grew on
average 78% faster, produced 56% and 16% more leaf mass and ergosterol,
and showed 78% higher leaf N uptake than slow-growing genotypes. The
insecticide decreased leaf damage by 83% and increased shoot growth, leaf
growth and leaf N uptake by 38%, 52% and 76%, without differences between
the responses of fast-growing and slow-growing genotypes, whereas root
mass decreased with increasing grass cover. Shoot and leaf growth of
fast-growing genotypes decreased and EM fungal production of slow-growing
genotypes increased with increasing grass cover. Our results suggest that
fast growth is genotypically associated with higher allocation to EM
fungi, better soil N capture and greater leaf production, and that the
tradeoff of fast growth is sensitivity to competition, but not to insect
herbivory. EM fungi may have a dual role: to support growth of
fast-growing genotypes under low grass competition and to maintain growth
of slow-growing genotypes under intensifying competition.