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

Brian S. Steidinger, Benjamin L. Turner, Adrianna Corrales, James W. Dalling

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

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 (AM) (angiosperm and conifer), ectomycorrhizal (EM) 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 EM tree species expressed twice the phosphomonoesterase activity as the AM 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 EM species did not perform better than the AM 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 AM and EM 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.

Original languageEnglish (US)
Pages (from-to)121-130
Number of pages10
JournalFunctional Ecology
Volume29
Issue number1
DOIs
StatePublished - Jan 1 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics

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