Lianas and trees exhibit distinct hydraulic and functional traits in a subtropical forest

Lianas are woody vines that rely on host trees for support to access the
forest canopy. Lianas typically occur in tropical and subtropical forests
and coexist with trees in subtropical secondary forests, where their
interactions strongly influence forest communities and ecosystem
functioning. We compared stem and leaf traits of lianas and trees to
examine the effects of growth form and leaf habit. We measured 20
functional traits (9 stem anatomical/hydraulic and 11 leaf morphological /
nutrient) from 10 liana and 14 tree species coexisting in a subtropical
forest of South China. Lianas exhibited 3.5-fold higher sapwood specific
conductivity (Ks) than trees, as well as higher predawn leaf water
potential (Ψpredawn) and hydraulically weighted vessel diameter (Dh).
Additionally, the maximum vessel diameter (Dmax) of lianas is
approximately three times higher than that of trees, and the theoretical
hydraulic conductivity (Kp) was ~20 times higher than trees. Functional
trait analysis indicated that lianas grouped separately from trees along a
leaf and stem economics spectrum: lianas were grouped at the fast end of
the plant economics spectrum, with high hydraulic diameter (Dh) and high
nitrogen (N) and phosphorus (P) concentration, exhibiting an
acquisition-focused water and nutrient strategy, permitting rapid growth
and tissue turnover. Trees were grouped at the low end of the plant
economics spectrum, with a high C: N ratio, high vessel thickness/diameter
(VT/VD), and high wood density (WD), exhibiting a conservative resource
acquisition strategy. Moreover, lianas exhibited significantly higher
modularity in their trait networks compared to trees (0.490 vs. 0.345; P =
0.043), reflecting stronger local integration of function, with tightly
coordinated traits that may enhance system adaptability by limiting the
spread of local drought-induced stress. These findings improve our
understanding of the mechanisms shaping ecological strategies across woody
plants with different growth forms and leaf habits, and address the
limited trait-based knowledge of subtropical forests relative to the
tropics. This study provides novel insight into how growth form and leaf
habit shape resource acquisition and niche partitioning in co-occurring
woody species in subtropical and secondary forests.