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Growth in epiphytic bromeliads: response to the relative supply of phosphorus and nitrogen
Author(s) -
Zotz G.,
Asshoff R.
Publication year - 2010
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1111/j.1438-8677.2009.00216.x
Subject(s) - epiphyte , biology , nutrient , relative growth rate , phosphorus , nitrogen , botany , zoology , limiting , growth rate , ecology , mechanical engineering , geometry , mathematics , materials science , physics , metallurgy , quantum mechanics , engineering
Insufficient nitrogen (N) and phosphorus (P) frequently limit primary production. Although most nutrient studies on vascular epiphytes have focused on N uptake, circumstantial evidence suggests that P rather than N is the most limiting element for growth in this plant group. We directly tested this by subjecting a total of 162 small individuals of three bromeliad species ( Guzmania monostachia , Tillandsia elongata , Werauhia sanguinolenta ) to three N and three P levels using a full‐factorial experimental design, and determined relative growth rates (RGR) and nutrient acquisition over a period of 11 weeks. Both N and P supply had a significant effect on RGR, but only tissue P concentrations were correlated with growth. Uptake rates of N and P, in contrast, were not correlated with RGR. Increased nutrient supply led to an up to sevenfold increase in tissue P concentration compared to natural conditions, while concentrations of N hardly changed or even decreased. All treatment combinations, even at the lowest experimental P supply, led to decreased N:P ratios. We conclude that P is at least as limiting as N for vegetative function under natural conditions in these epiphytic bromeliads. This conclusion is in line with the general notion of the prevalence of P limitation for the functioning of terrestrial vegetation in the tropics.