Data from: Variability in potential to exploit different soil organic phosphorus compounds among tropical montane tree species

We hypothesized that tropical plant species with different mycorrhizal
associations reduce competition for soil phosphorus (P) by specializing to
exploit different soil organic P compounds. We assayed the activity of
root/mycorrhizal phosphatase enzymes of four tree species with contrasting
root symbiotic relationships–arbuscular mycorrhizal (angiosperm and
conifer), ectomycorrhizal and non-mycorrhizal–collected from one of three
soil sites within a montane tropical forest. We also measured growth and
foliar P of these seedlings in an experiment with P provided exclusively
as inorganic orthophosphate, a simple phosphomonoester (glucose
phosphate), a phosphodiester (RNA), phytate (the sodium salt of
myo-inositol hexakisphosphate), or a no-P control. The ectomycorrhizal
tree species expressed twice the phosphomonoesterase activity as the
arbuscular mycorrhizal tree species, but had similar phosphodiesterase
activity. The non-mycorrhizal Proteaceae tree had markedly greater
activity of both enzymes than the mycorrhizal tree species, with root
clusters expressing greater phosphomonoesterase activity than fine roots.
Both the mycorrhizal and non-mycorrhizal tree species contained
significantly greater foliar P than in no-P controls when limited to
inorganic phosphate, glucose phosphate, and RNA. The ectomycorrhizal
species did not perform better than the arbuscular mycorrhizal tree
species when limited to organic P in any form. In contrast, the
non-mycorrhizal Proteaceae tree was the only species capable of exploiting
phytate, with nearly three times the leaf area and more than twice the
foliar P of the no-P control. Our results suggest that arbuscular and
ectomycorrhizal tree species exploit similar forms of P, despite
differences in phosphomonoesterase activity. In contrast, the mycorrhizal
tree species and non-mycorrhizal Proteaceae appear to differ in their
ability to exploit phytate. We conclude that resource partitioning of soil
P plays a coarse but potentially ecologically important role in fostering
the coexistence of tree species in tropical montane forests.