Tropical terrestrial and epiphytic ferns have different leaf stoichiometry with ecological implications

Abstract

Terrestrial and epiphytic herbaceous forest species have different ecological qualities and leaf stoichiometry. Ferns represent a great component of herbaceous forest species in tropical regions with different lifeforms and evolutionary histories. However, little is known about the differences in leaf stoichiometry between the lifeforms. We studied the concentrations of leaf elements (N, P, K, Ca and Mg) between lifeforms (16 terrestrial, 4 epiphytic) and evolutionary clades (12 polypods, 8 non-polypods). The leaves were collected from the field, acid-digested and analyzed for nutrient elements. Results show that epiphytic species had a higher concentration of most leaf elements. Epiphytes had a lower N:P ratio compared with terrestrial ones. This suggests that epiphytes were nutrient-limited, relying on stochastic elements supply compared to terrestrial species which have a constant supply. Epiphytes tend to accumulate higher element concentration beyond their immediate metabolic needs, defined as luxury consumption. Epiphytes showed a higher concentration of P and Ca for their necessity of coping with severe habitat conditions and sclerophyll leaves. We found that modern polypod and archaic non-polypod ferns are significant stoichiometry different for K. The results contribute to the context of the poorly studied stoichiometry of tropical Asian fern species and their ecophysiology.

Keywords:

• Plant physiology
• sclerophyll
• polypodiales
• vascular epiphytes
• luxury consumption
• plant nutrition
• borneo

Acknowledgements

We would like to acknowledge the Department of Forestry of Brunei Darussalam, for the provision of species sampling in the forest reserves. We are grateful to our research assistants Nurhazwani Sirun and Nur Fauziah Haji Yahya for their assistance when species sampling as well as Nur Aqilah Haji Zainal Ariffin for their help when species sampling and in the editing of Figure 2. We would also like to thank the lab technicians from the Environmental and Life Sciences Department for their logistical support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was supported by the Government of Brunei Darussalam through the Ministry of Education (Brunei Government Scholarship to S.P.S.).