Laube & Zotz 2003 (Article) Panama, Werauhia

Which abiotic factors limit vegetative growth in a vascular epiphyte?

Author(s):—S. Laube & G. Zotz

Publication:—Ecology 17: 598–604. (2003)

Abstract:—1. Vegetative growth in vascular epiphytes is assumed to be severely limited by inter-mittent supply of water and nutrients, but experimental evidence for this notion ismeagre. The effects of water, nutrient supply and light on growth were studied in anepiphytic bromeliad, Vriesea sanguinolenta Cogn. & Marchal (syn. Werauhia sanguino-lenta ) in a large forest gap in a lowland forest of Panama, in a full-factorial design. Toinvestigate ontogenetic drift, three plant-size classes ( ≈ 5, 15 and 35 cm leaf length) wereincluded in the experiment.
2. Water supply had the strongest influence on growth, but the magnitude of this effectdiffered considerably among size classes. Nutrient supply affected growth only in smalland intermediate-sized plants. More light (60% of direct irradiation) tended to decreasegrowth rates compared to 30% irradiation.
3. Small plants showed by far the highest potential to adjust their relative growth rate(RGR) in response to favourable growing conditions.
4. Despite these size-related differences, absolute RGRs were extremely low comparedto studies with other plant groups, confirming the notion that vascular epiphytes areinherently slow-growing plants.

Keywords:—growth, ontogenetic drift, Panama, rainforest, RG