Lianas suppress seedling growth and survival of 14 tree species in a Panamanian tropical forest

Abstract

.Lianas are a common plant growth form in tropical forests, where they compete intensely with trees, decreasing tree recruitment, growth, and survival. If the detrimental effects of lianas vary signifi cantly with tree species identity, as is often assumed, then lianas may infl uence tree species diversity and community composition. Furthermore, recent studies have shown that liana abundance and biomass are increasing relative to trees in neotropical forests, which will likely magnify the detrimental effects of lianas and may ultimately alter tree species diversity, relative abundances, and community composition. Few studies, however, have tested the responses of multiple tree species to the presence of lianas in robust, well-replicated experiments. We tested the hypotheses that lianas reduce tree seedling growth and survival, and that the effect of lianas varies with tree species identity. We used a large-scale liana removal experiment in Central Panama in which we planted 14 replicate seedlings of 14 different tree species that varied in shade tolerance in each of 16 80 × 80 m plots (eight liana-removal and eight unmanipulated controls; 3136 total seedlings). Over a nearly two-yr period, we found that tree seedlings survived 75% more, grew 300% taller, and had twice the aboveground biomass in liana-removal plots than seedlings in control plots, consistent with strong competition between lianas and tree seedlings. There were no signifi cant differences in the response of tree species to liana competition (i.e., there was no species by treatment interaction), indicating that lianas had a similar negative effect on all 14 tree species. Furthermore, the effect of lianas did not vary with tree species shade tolerance classifi cation, suggesting that the liana effect was not solely based on light. Based on these fi ndings, recently observed increases in liana abundance in neotropical forests will substantially reduce tree regeneration, but will not signifi cantly alter tropical tree species diversity, relative abundance, or community composition.

Evaluating climber cutting as a strategy to restore degraded tropical forests

“…This benefit was only obtained, however, when enrichment planting was implemented right after climber cutting. These results suggest that for enrichment planting to be successful, plantings should be concentrated in large gaps where light levels are higher or ongoing overstory clearing will be necessary (Bertacchi et al, 2016;Martínez-Izquierdo et al, 2016).…”

Facilitation, competition and parasitic facilitation amongst invasive and native liana seedlings and a native tree seedling

“…As expected, plants that grew at low light increased their SLA through an increase in the area of leaf relative to the biomass of the leaf, however, all lianas grew equally well in both light treatments and there was no increase in the proportional effect of neighbouring plants on biomass. This suggests that these lianas grow equally quickly in both the interior and edges of rainforests and, in a similar way to lianas in tropical forests, have the capacity to impact on tree seedlings in gaps (Schnitzer and Carson 2010) and in understorey (Martinez-Izquierdo et al 2016). While Toledo-Aceves and Swaine (2008) also found no interaction between competition and light, they did find that growth was enhanced with higher light in tropical rainforests.…”

“…However, within forest interiors, resource limitation, particularly phosphorus, is important for both trees and lianas although lianas always outperform trees (Pasquini et al 2015) and can suppress seedling growth and survival (Martinez-Izquierdo et al 2016). Thus comparing competitive and facilitatory effects at the edges and interiors of rainforests may indicate the strength of competition, relative importance of facilitation and how effective lianas are in these early periods of growth.…”

Effect of lianas on forest‐level tree carbon accumulation does not differ between seasons: Results from a liana removal experiment in Panama

“…Control plots were visited at the same frequency and intensity as the liana removal plots, to avoid a visitation effect (Cahill, Castelli, & Casper, ; Schnitzer, Reich, Bergner, & Carson, ) and the liana removal plots have been kept liana‐free until present. The liana removal experiment follows the fate of more than 30,000 lianas and trees >1 cm diameter to assess the forest‐level impacts of lianas on forest community and ecosystem level dynamics (Adams, Schnitzer, & Yanoviak, ; Álvarez‐Cansino et al, ; García León et al, ; Martínez‐Izquierdo, García, Powers, & Schnitzer, ; Rodriguez‐Ronderos, Bohrer, Sanchez‐Azofeifa, Powers, & Schnitzer, ; van der Heijden et al, ). This paper presents results of the first 6 years (2011–2017) of the experiment and focuses on 841 lianas ≥5 cm and 2,717 trees ≥10 cm, which comprise the vast majority of the woody plant biomass in this forest.…”