Leaf and Stem Traits are Linked to Liana Growth Rate in a Subtropical Cloud Forest

Abstract

There is accumulating evidence that the abundance and biomass of lianas are increasing with global climate change in the Neotropics. However, our knowledge of growth–trait relationships among lianas is surprisingly rare. Here, we monitored the relative growth rate of 2860 individuals from seven deciduous and four evergreen liana species in a 20 ha subtropical cloud forest dynamics plot at high elevation (2472–2628 m a.s.l.) in southwest China. We linked the relative growth rate of lianas with nine leaf traits associated with leaf morphology, nutrient concentrations, and water hydraulic capacity as indicated by leaf vein density, and five stem wood traits related to stem water transport capacity and wood density. Our results showed that deciduous lianas have higher relative growth rates than their evergreen counterparts. Across all lianas studied, the relative growth rate was positively correlated with the leaf area and specific leaf area, but negatively correlated with leaf dry matter content. The relative growth rate of lianas was strongly correlated with nitrogen concentration after excluding the legume liana species. The relative growth rate was decoupled from leaf phosphorus and potassium concentrations, leaf vein density, and stem vessel traits across all lianas investigated. For four evergreen lianas, there were positive associations of the relative growth rate with the leaf thickness and diameter of the largest vessels. This study is the first to illustrate the relationships of liana growth with leaf and stem traits in the high-elevation subtropical cloud forest. More studies from diverse forest ecosystems are needed to comprehensively understand the mechanism underlying liana growth patterns.

Climbing mechanisms as a central trait to understand the ecology of lianas across the tropics

“…However, in contrast to trees, the rate of stem elongation, more than the investment in diameter increase, plays a central role in the liana's ability to find a suitable support. For instance, there is evidence that lianas exhibit higher rates of shoot elongation compared with trees (Bai et al., 2020; Ichihashi & Tateno, 2015; Roeder et al., 2012; Schnitzer, 2005), and that active species have higher rates of shoot elongation compared with passive species (Teramura et al., 1991). The functional trait differences we found between the active and passive species support the idea of active climbing species having faster growth towards fully exposed conditions in the upper forest canopy and benefiting from a more acquisitive strategy.…”