title: Potassium, phosphorus, or nitrogen limit root allocation, tree growth, or litter production in a lowland tropical forest.
abstract: We maintained a factorial nitrogen (N), phosphorus (P), and potassium (K) addition experiment for 11 years in a humid lowland forest growing on a relatively fertile soil in Panama to evaluate potential nutrient limitation of tree growth rates, fine-litter production, and fine-root biomass. We replicated the eight factorial treatments four times using 32 plots of 40 x 40 m each. The addition of K was associated with significant decreases in stand-level fine-root biomass and, in a companion study of seedlings, decreases in allocation to roots and increases in height growth rates. The addition of K and N together was associated with significant increases in growth rates of saplings and poles (1-10 cm in diameter at breast height) and a further marginally significant decrease in stand-level fine-root biomass. The addition of P was associated with a marginally significant (P = 0.058) increase in fine-litter production that was consistent across all litter fractions. Our experiment provides evidence that N, P, and K all limit forest plants growing on a relatively fertile soil in the lowland tropics, with the strongest evidence for limitation by K among seedlings, saplings, and poles.
authors: Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Republic of Panama. wrightj@si.edu
authors: S Joseph
authors: SJ
authors: Wright
authors: Joseph B
authors: JB
authors: Yavitt
authors: Nina
authors: N
authors: Wurzburger
authors: Benjamin L
authors: BL
authors: Turner
authors: Edmund V J
authors: EV
authors: Tanner
authors: Emma J
authors: EJ
authors: Sayer
authors: Louis S
authors: LS
authors: Santiago
authors: Michael
authors: M
authors: Kaspari
authors: Lars O
authors: LO
authors: Hedin
authors: Kyle E
authors: KE
authors: Harms
authors: Milton N
authors: MN
authors: Garcia
authors: Marife D
authors: MD
authors: Corre
mesh_terms: D017753:Ecosystem; D009584:Nitrogen / Q000737:chemistry / Q000494:pharmacology*; D010758:Phosphorus / Q000737:chemistry / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development*; D011188:Potassium / Q000737:chemistry / Q000494:pharmacology*; D012987:Soil / Q000737:chemistry; D014197:Trees / Q000187:drug effects / Q000254:growth & development*; D014329:Tropical Climate
chemical_list: D012987:Soil; D010758:Phosphorus; D009584:Nitrogen; D011188:Potassium