Abstract
Tree ferns are conspicuous in subtropical and tropical rainforests. Some closely related
species of tree ferns often coexist in the forest; however, the mechanisms are poorly
understood. The ecophysiological characteristics of 3 tree ferns, Cyathea lepifera,
C. spinulosa, and C. podophylla, growing in forests of northeastern Taiwan were
investigated. Results showed that C. lepifera preferred an open habitat (mean canopy
openness (MCO) of 29.2%), while C. spinulosa and C. podophylla preferred a shaded
habitat (MCOs of 7.0 and 5.0%, respectively). The light-saturated photosynthetic rate of
C. lepifera was significantly higher than that of C. podophylla, and C. spinulosa had a
medium one (11.46, 8.27, and 6.34 μmol CO2 m-2 s-1 for C. lepifera, C. spinulosa, and C.
podophylla, respectively). The light saturation point of C. podophylla was significantly lower
than those of the other 2 species (1220, 1100, and 808 μmol photon m-2 s-1 for C. lepifera,
C. spinulosa, and C. podophylla, respectively). The light compensation point (LCP) and dark respiration rate (Rd) of C. lepifera were significantly higher than those of C. spinulosa and C. podophylla. Cyathea lepifera had the shortest frond life spans (6.6 mo for fertile fronds and
7.2 mo for sterile fronds) among the 3 species, which was followed by those of C. spinulosa
(7.2 mo for fertile fronds and 7.3 mo for sterile fronds), and the longest frond life spans were
in C. podophylla (13.0 mo for fertile fronds and 12.0 months for sterile fronds). Cyathea
lepifera, C. spinulosa, and C. podophylla respectively belonged to shade-intolerant species,
mid-shade-tolerant species, and shade-tolerant species as inferred from their habitat preference
and ecophysiological characteristics. Roads, trails, frequent typhoons, and occasional tree falls create habitats with different canopy openness levels which increase the opportunity of these 3 Cyathea species to coexist in this forest.