Responses of a common tropical epiphyte, Asplenium nidus, to changes in water and nutrient availability

Xiao-Zhen Chen; J Aaron Hogan; Chiao-Ping Wang; Pei-Ling Wang; Teng-Chiu Lin

doi:10.1093/aobpla/plad076

Responses of a common tropical epiphyte, Asplenium nidus, to changes in water and nutrient availability

AoB Plants. 2023 Nov 9;15(6):plad076. doi: 10.1093/aobpla/plad076. eCollection 2023 Dec.

Authors

Xiao-Zhen Chen¹, J Aaron Hogan², Chiao-Ping Wang³, Pei-Ling Wang⁴, Teng-Chiu Lin¹

Affiliations

¹ Department of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan.
² Department of Biology, University of Florida, Gainesville, FL 32611, USA.
³ Silviculture Division, Taiwan Forestry Research Institute, Taipei 10066, Taiwan.
⁴ Institute of Oceanography, National Taiwan University, Taipei 10617, Taiwan.

Abstract

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 can affect plant growth but few studies have evaluated the effects of changes in both water and nutrient availabilities on epiphytes. We experimentally tested whether epiphyte growth is more water- or nutrient-limited, if nutrient limitation was stronger for nitrogen or phosphorus, and whether nutrient limitation interacts with water availability. We applied watering (high and low) and nutrient addition (control, +N, +P, +N+P) treatments to greenhouse-grown Asplenium nidus, a common epiphytic fern found in many tropical and subtropical wet forests. We measured leaf area production and leaf elemental concentrations to assess how A. nidus growth and physiology respond to changes in water and nutrient availabilities. We found that leaf growth of A. nidus was more affected by water availability than nutrient addition and the effect of adding nutrients was not fully realized under low-water availability. Among the different nutrient treatments, +N+P had the greatest effects on A. nidus growth and physiology in both watering treatments. Watering treatment changed leaf elemental concentrations but not their ratios (i.e. C:N and N:P). Nutrient addition altered C:N and N:P ratios and increased the concentration of the added elements in leaves, with more pronounced increases in the high-watering treatment. We conclude that the growth of A. nidus is more water- than nutrient-limited. When nutrient limitation occurs (i.e. under high-water availability), nutrient co-limitation is stronger than limitation by N or P alone. This result taken together with studies of other epiphytes suggests greater water than nutrient limitation is likely widespread among epiphytic plants. The limited effects of nutrient addition in the low-water treatment suggest that the effect of atmospheric N deposition on epiphyte growth will be limited when water availability is low.

Keywords: Asplenium nidus; atmospheric deposition; climate change; co-limitation; epiphytes; nutrient limitation; water stress.