Abstract
Abstract Lianas, a key component of tropical forests, can limit growth of trees, impacting both the structure and functioning of forests, and are expected to benefit from fragmentation and potentially from global climatic changes. While it is critical to understand the impacts of liana infestation on contemporary tropical forests across large geographical areas, to date most liana studies have been focussed on single or few sites. We measured and quantified liana infestation of 16,066 trees with diameter ≥10 cm in 27 plots distributed across southern Amazonia, a region characterized by substantial ecological and environmental variation and environmental change. We examined the influence of potential drivers of liana infestation at the plot, species and individual tree level. Additionally, we evaluated the effect of liana infestation on tree growth. More than half of all trees had lianas in their crown. At the plot level, infestation by lianas was driven by forest structure but not by the studied climate or soil fertility variables, though low levels of liana infestation were found in seasonally flooded forests. At the tree level, larger and stouter trees had a greater proportion of their crown infested with lianas. At the species level, trees belonging to intrinsically slow‐growing, dense‐wooded species were more susceptible to liana infestation. Liana infestation had a negative impact on tree growth, with growth of heavily infested trees reduced by 33% compared to non‐infested. The impact of liana infestation on tree growth was strongest for the best‐lit tree crowns, indicating that lianas act to reduce the large competitive advantage that well‐lit trees otherwise hold over their neighbours. Synthesis. Lianas are a pervasive and influential feature of the extensive forests at the southern edge of Amazonia. The degree of liana infestation in forests was closely linked to species‐level variables such as potential growth and wood density as well as the size of the individual tree. The growth of heavily infested trees was particularly restricted by lianas, and especially so for trees growing in otherwise favourable conditions, indicating the potential for lianas not only to reduce forest growth rates overall, but also to modify competitive hierarchies among trees within tropical forests.
Highlights
Lianas are a major floristic component of tropical forests, but by using trees for support they play a significant role in determining tropical forest structure, dynamics and ecosystem function
In forests across the southern border region of Amazonia, more than half of the 16,066 trees examined were infested by lianas, yet variation in plot-level infestation rates was not obviously influenced by environmental variables such as fragmentation, precipitation and soil fertility
Liana infestation in turn had a negative influence on tree growth, with trees growing in high light conditions experiencing more negative impacts of liana infestation having their growth especially strongly reduced
Summary
Lianas are a major floristic component of tropical forests, but by using trees for support they play a significant role in determining tropical forest structure, dynamics and ecosystem function. As lianas can exert strong stomatal control by which carbon fixation is maximized whilst minimizing water loss (Cai, Schnitzer, & Bongers, 2009; Campanello et al, 2016), they are hypothesized to derive a growth advantage over trees in forested tropical areas with high climatic seasonality and relatively low rainfall (DeWalt et al, 2010; Schnitzer, 2005; Schnitzer & Bongers, 2011; Schnitzer & van der Heijden, 2019). We assessed the consequences of infestation by investigating tree-level growth trajectories and their potential drivers We used this information to contribute to tackling two fundamental questions to understand the ecology and impacts of lianas in tropical forests: (a) What factors determine liana infestation in tropical trees, species and forests? We used this information to contribute to tackling two fundamental questions to understand the ecology and impacts of lianas in tropical forests: (a) What factors determine liana infestation in tropical trees, species and forests? (b) How important are the impacts of lianas on tree growth relative to other well-known determinants, such as tree size, wood density and light environment? Based on studies cited above we anticipated that liana infestation will be: (a) positively related to key forest structural variables (tree diameter, height, basal area, density, percentage of broken trees); (b) negatively associated with growth rate of tree species, and (c) positively related to wood density of tree species; (d) negatively related to precipitation and (e) positively related to maximum climatological water deficit, (f) positively related to soil fertility and (g) to fragmentation (e.g. fragment area, edge distance) and (h) negatively related to treelevel growth rate
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
