Zotz & Laube 2005 (Article) Catopsis

Tank function in the epiphytic bromeliad, Catopsis sessiliflora

Author(s):—G. Zotz & S. Laube

Publication:—ECOTROPICA 11: 63–68. (2005)

Abstract:—Water-impounding tank bromeliads have gained a certain independence of the intermittent water supply in treecrowns, but quantitative studies on the effectiveness of these tanks to bridge rainless periods are rare. We tested the hypothesis that the vertical orientation of tanks changes during ontogeny resulting in an even stronger reduction of the effectiveness of smaller tanks than suggested by earlier studies. Observations on Catopsis sessiliflora (R. & P.) Mez. in a lowland forest in Panama (San Lorenzo) showed that smaller plants are indeed more horizontally oriented than larger conspecifics. Surprisingly,experimental variation of the angle of the vertical axis of a plant relative to the perpendicular of up to 60°did not affect the time until a tank ran dry. Similar to species with multi-chambered tanks, however, tank function of this single-chamberedtank species was strongly size-dependent: the tanks of large plants supplied water about five times longer than those of smaller conspecifics.

Keywords:—growth , RGR , San Lorenzo crane site , size dependency , water relations .