Tropical Terrestrial And Epiphytic Ferns Have Different Leaf Stoichiometry With Ecological Implications.

Abstract

Terrestrial and epiphytic herbaceous forest species have different ecology and leaf stoichiometry. In tropical regions, a great component of herbaceous forest species is represented by ferns with different lifeforms. However, little is known about the differences in leaf stoichiometry between the lifeforms. We account for the concentrations of leaf elements (N, P, K, Ca and Mg) between terrestrial and epiphyte lifeforms and evolutionary clades. The fern species were sampled from the forest of Brunei Darussalam. Five leaves were collected from 5 individuals from 16 terrestrial and 4 epiphytic ferns. The leaves were then acid-digested and analyzed. Epiphytic species had higher concentration of most of the leaf elements. The N:P ratio showed that the epiphytic species being much more nutrient-limited, relying on stochastic events, compared to the terrestrial species which have a constant availability of soil elements. Epiphytes showed a higher concentration of P, which could be explained by their luxury consumption. Epiphytes accumulate elements in a higher concentration than is needed by their normal metabolic activity. Furthermore, epiphyte species have a significantly higher concentration of Ca which could be interpreted as necessity of coping with severe habitat conditions with schlerophyll leaves. The results bring in more information on the poorly studied stoichiometry of tropical Asian fern species. Important in understanding the eco-physiology of terrestrial and epiphytic ferns and determining which species are sensitive to the different forest management and the effect of climate change. This, is in addition to the associated mechanisms.