Removing climbers more than doubles tree growth and biomass in degraded tropical forests

Abstract

Huge areas of tropical forests are degraded, reducing their biodiversity, carbon, and timber value. The recovery of these degraded forests can be significantly inhibited by climbing plants such as lianas. Removal of super‐abundant climbers thus represents a restoration action with huge potential for application across the tropics. While experimental studies largely report positive impacts of climber removal on tree growth and biomass accumulation, the efficacy of climber removal varies widely, with high uncertainty as to where and how to apply the technique. Using meta‐analytic techniques, we synthesize results from 26 studies to quantify the efficacy of climber removal for promoting tree growth and biomass accumulation. We find that climber removal increases tree growth by 156% and biomass accumulation by 209% compared to untreated forest, and that efficacy remains for at least 19 years. Extrapolating from these results, climber removal could sequester an additional 32 Gigatons of CO2 over 10 years, at low cost, across regrowth, and production forests. Our analysis also revealed that climber removal studies are concentrated in the Neotropics (N = 22), relative to Africa (N = 2) and Asia (N = 2), preventing our study from assessing the influence of region on removal efficacy. While we found some evidence that enhancement of tree growth and AGB accumulation varies across disturbance context and removal method, but not across climate, the number and geographical distribution of studies limits the strength of these conclusions. Climber removal could contribute significantly to reducing global carbon emissions and enhancing the timber and biomass stocks of degraded forests, ultimately protecting them from conversion. However, we urgently need to assess the efficacy of removal outside the Neotropics, and consider the potential negative consequences of climber removal under drought conditions and for biodiversity.

Lianas (Vitis spp.) reduce growth and carbon sequestration of light‐demanding tree species in a temperate forest

“…Therefore, we suspect that lianas are less efficient at removing CO 2 per unit of growing space they occupy compared to trees. Finlayson et al (2022) found large net benefits in carbon removal by trees following liana removal in tropical regions, after accounting for emissions due to decay of cut lianas. Such net CO 2 flux calculations are an important next step for research in Appalachian liana management.…”

“…Prior research reporting on the impacts of lianas on carbon storage has focused on the neotropics (van der Heijden et al 2013;Schnitzer et al 2014;Finlayson et al 2022), and we are unaware of such studies in temperate forests. However, unlike tropical forests, trees in temperate forests including Appalachia produce annual growth rings: reliable indicators of tree age that allow us to quantify relationships between liana presence and tree growth rate over many decades with one season of data collection.…”

“…Lianas are structural parasites that, unlike trees, minimize allocation of resources to structural support, and hence have a dramatically lower ratio of carbon storage per unit leaf area (Darwin 1865; Della‐Bianca 1979; Putz & Mooney 1992). Furthermore, lianas have been shown to significantly impact tropical forest carbon stocks (Durán & Gianoli 2013; Schnitzer et al 2014; Finlayson et al 2022). In tropical forests, large trees comprise upwards of 90% of overall biomass, but are frequently colonized by lianas, reducing their carbon storage potential (Durán & Gianoli 2013).…”

Fifteen essential science advances needed for effective restoration of the world's forest landscapes

“…In moist and wet forests, lianas and other vines are affecting the recovery of disturbed forests on a pantropical scale, with growing evidence suggesting a second tipping point in forest recovery [ 140 ]. However, there is debate regarding the benefit of temporary removal by cutting to stimulate tree growth [ 141 ], including potentially negative impacts for biodiversity, drought and protective ‘bandage effects’ on regrowing trees [ 118 , 140 ]. Knowledge is even more limited for other shrubby and herbaceous plants.…”

Corrigendum

“…In the article by Finlayson et al (2022), titled “Removing climbers more than doubles tree growth and biomass in degraded tropical forests”, the authors note an error. The paper misinterprets the standardized mean difference (SMD) summary effect size, resulting in an overestimation of the effect of climber removal on tree growth and biomass and an overestimation of the global carbon sequestration potential of climber removal.…”