The length, width and numbers of fronds of Taiwan Nest fern, Taiwan, Taipei, 2021-2022.

Background and aims Epiphytes are highly dependent on atmospheric inputs of water and nutrients. Reductions in water availability associated with warming and climate change and continual atmospheric nitrogen (N) deposition are known to affect plant growth but no studies have evaluated these effects on epiphytes. We experimentally tested whether epiphyte growth is more limited by water or nutrients, limitation was stronger regarding nitrogen and phosphorus, and whether nutrient limitation interacts within water availability. Methods We in a greenhouse assessed the effects of water availability (high and low) and nutrient addition (control, +N, +P, +N+P) on the growth and nutrient composition of Asplenium nidus, an epiphyte common to tropical and subtropical humid forests. Leaf area was measured monthly for one year and foliar elemental concentrations were measured before and at the end of the experiment.