Ficus is the largest genus containing woody hemiepiphytes (~500 species), in which the hemiepiphytic growth habit is likely to have evolved multiple times from terrestrial lineages of Ficus ancestors (Berg and Corner 2005, Harrison 2005).
Dr. Hao Guangyou and his supervisor Prof. Cao Kunfang of Xishuangbanna Tropical Botanical Garden (XTBG) examined leaf gas exchange and chlorophyll fluorescence in response to changes in irradiance levels in five hemiepiphytes (Hs) and five non-hemiepiphytes (NHs) of Ficus with all the hemiepiphytic plants being terrestrially rooted adult tree.
Two questions were addressed: (1) Do Hs and NHs of Ficus differ significantly in photosynthetic traits, such as net CO2 assimilation rate (An),efficiency of non-photochemical energy dissipation of PSII(ΦNPQ) and photorespiration rate under conditions of excessively high irradiance? (2) Across Ficus species, are photosynthetic traits correlated with stem hydraulic conductivity?
The study was carried out in the Xishuangbanna Tropical Botanical Garden (XTBG) (21°56′N, 101°15′E, 600 m altitude) of the Chinese Academy of Sciences, Yunnan, SW China. The 10 study species were all from the genus Ficus with five Hs and five NHs that are commonly found in the rainforests of Xishuangbanna.
The research findings indicate that a canopy growth habit during early life stages in Hs of Ficus resulted in substantial adaptive differences from congeneric NHs not only in water relations but also in photosynthetic light use and carbon economy. The evolution of epiphytic growth habit, even for only part of their life cycle, involved profound changes in a suite of inter-correlated ecophysiological traits that persist to a large extent even during the later terrestrial growth phase.
The study entitled “Differentiation in light energy dissipation between hemiepiphytic and non-hemiepiphytic Ficus species with contrasting xylem hydraulic conductivity” has been published in Tree Physiology, 31(6): 626-636, doi:10.1093/treephys/tpr035