Photosynthetic Characteristics of 13 Liana Species in a Karst Rocky Mountain Area:A Comparative Study of Woody and Herbaceous Growth Forms

Lianas are important components of tropical and subtropical ecosystems, yet their photosynthetic adaptation and resource-use strategies under stressful karst environments remain poorly understood. In particular, whether woody and herbaceous lianas exhibit distinct photosynthetic strategies remains largely unknown. This study investigated the the photosynthetic characteristics and resource-use strategies of 13 dominant liana species (nine woody and four herbaceous) from karst rocky mountain area in northern Guangxi, China. Photosynthetic parameters were derived using the non-rectangular hyperbola model. Growth form differences were assessed via t-tests and Mann-Whitney U tests. Relationships among traits were explored using Pearson correlation and principal component analysis (PCA). Results showed considerable interspecific variation: A max ranged from 4.00 to 13.39 µmol m − 2 s − 1 (mean 8.01), AQY from 0.028 to 0.095 (mean 0.070), LSP from 804 to 1538 µmol m − 2 s − 1 (mean 1098), and LCP from 14.0 to 38.1 µmol m − 2 s − 1 (mean 25.3). No significant differences were found between woody and herbaceous lianas for any parameter (Mann-Whitney U, all p > 0.05). PCA resolved two principal axes—resource acquisition-conservation and light-use-water economy—accounting for 64.3% of trait variation, but no clear separation by growth form was observed. Hierarchical clustering identified three clusters not strictly corresponding to growth form. Our findings demonstrate that photosynthetic differentiation in karst lianas is primarily associated with ecological strategies rather than growth-form differences. This suggests that selective pressures of the karst environment may override morphological differences between growth forms. This study provides valuable baseline data on liana photosynthetic physiology in karst ecosystems.