Ecological stoichiometry and nutrient dynamics of substrates in hemi-epiphytic figs (Ficus tinctoria subsp. gibbosa (Bl.) Corner) during different growth stages

Ficus tinctoria subsp. gibbosa (Bl.) Corner is the most "strangling" hemi-epiphytic fig in tropical forests. Its life history changes from epiphytic seedling to transitional juvenile and free-standing adult stages, with growth substrate shifting from canopy humus to soil. Here, we measured the concentrations of total carbon (TC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), total calcium (Ca) and total magnesium (Mg), as well as the stoichiometric ratio of C:N:P,in substrates of the hemi-epiphytic fig (F. tinctoria) during different growth stages in Xishuangbanna, Yunnan Province, China. Results showed that the TC, TN, TP, TK, and Mg concentrations were significantly higher in canopy humus than in forest floor humus, while Ca content was lower. Both TC and TN concentrations were higher in the epiphytic and free-standing adult stages than in the hemi-epiphytic stage. Soil TP concentration was lower in the hemi-epiphytic stage than other stages. The soil C:N and N:P ratios were the highest in the hemi-epiphytic stage, whereas the C:P ratio was lower. Both TC and TN were significantly positively correlated with the C:N, C:P and N:P ratios, while TP was significantly negatively correlated with C:P and N:P. The soil C:N, C:P and N:P ratios of the hemi-epiphytic fig in Xishuangbanna were lower than the national soil average in China. The hemi-epiphytic stage was obviously limited by soil P.