Differences in leaf caloric values and construction costs between liana and tree species in Bauhinia

To understand the leaf energy investment strategies of co-occurring lianas and trees, we investigated nine traits related to leaf nutrients, ash, caloric value, and leaf construction costs in 10 liana and 10 tree species of Bauhinia (Leguminosae). We also analyzed the differences in traits between two growth forms and the relationships among traits. Results showed that the means of the gross caloric value (GCV) and ash free caloric value (AFCV) of the 20 Bauhinia species were 18.64 kJ/g and 20.20 kJ/g, respectively. Both GCV and mass-based leaf construction cost were significantly and positively correlated with leaf carbon content, were significantly and negatively correlated with leaf ash content, and were significantly lower in lianas than in trees. Principal component analysis showed that lianas were negative loads of the first PCA axis with low leaf caloric values and mass-based construction costs, whereas trees showed the opposite pattern. These results indicated that, as typical tropical sun plants, Bauhinia species had some advantages in solar energy storage. Furthermore, liana and tree species in Bauhinia demonstrated different resource utilization and allocation strategies. The significantly lower caloric value, mass-based leaf construction cost, and leaf mass per area in lianas reflected a rapid resource turnover strategy, whereas trees exhibited a more conservative resource utilization strategy.