Seedling growth responses to phosphorus reflect adult distribution patterns of tropical trees.
Soils influence tropical forest composition at regional scales. In Panama, data on tree communities and underlying soils indicate that species frequently show distributional associations to soil phosphorus. To understand how these associations arise, we combined a pot experiment to measure seedling responses of 15 pioneer species to phosphorus addition with an analysis of the phylogenetic structure of phosphorus associations of the entire tree community. Growth responses of pioneers to phosphorus addition revealed a clear tradeoff: species from high-phosphorus sites grew fastest in the phosphorus-addition treatment, while species from low-phosphorus sites grew fastest in the low-phosphorus treatment. Traits associated with growth performance remain unclear: biomass allocation, phosphatase activity and phosphorus-use efficiency did not correlate with phosphorus associations; however, phosphatase activity was most strongly down-regulated in response to phosphorus addition in species from high-phosphorus sites. Phylogenetic analysis indicated that pioneers occur more frequently in clades where phosphorus associations are overdispersed as compared with the overall tree community, suggesting that selection on phosphorus acquisition and use may be strongest for pioneer species with high phosphorus demand. Our results show that phosphorus-dependent growth rates provide an additional explanation for the regional distribution of tree species in Panama, and possibly elsewhere.
Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Republic of Panama. camilozalamea@gmail.com.
Paul-Camilo
PC
Zalamea
Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Republic of Panama.
Benjamin L
BL
Turner
Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Republic of Panama.
Klaus
K
Winter
Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Republic of Panama.|Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331-2902, USA.
F Andrew
FA
Jones
Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Republic of Panama.
Carolina
C
Sarmiento
Smithsonian Tropical Research Institute, Apartado, 0843-03092, Balboa, Ancon, Republic of Panama.|Department of Plant Biology, University of Illinois, Urbana, IL, 61801, USA.
James W
JW
Dalling
D018533:Biomass; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010758:Phosphorus / Q000494:pharmacology*; D010802:Phylogeny; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D013045:Species Specificity; D014197:Trees / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D014329:Tropical Climate
D010758:Phosphorus; D010749:Phosphoprotein Phosphatases
phosphatase activity; phosphorus limitation; pioneer trees; plant communities; plant growth; species distributions; tropical soil resources