Evaluating climber cutting as a strategy to restore degraded tropical forests

Abstract

A substantial share of the remaining tropical forest cover is represented by historically degraded fragments exposed to severe edge effects, where ruderal plants proliferate vigorously and may arrest succession. We tested climber plant cutting as strategy to restore a semideciduous tropical forest remnant that is dominated by ruderal climbers. We compared control (unmanaged) plots with plots subjected to climber cutting at 1-m height with recutting one (after 8 months) or three times (8, 24 and 36 months). We monitored: 1) tree and shrub biomass gain and canopy openness for three years; 2) tree and shrub growth and recruitment of regenerating seedlings for one year; and 3) planted seedling survival for two years. Climber cutting increased biomass gain by~51% for smaller trees and shrubs (1.58 ≤ dbh b 5 cm) only, regardless of the number of re-cuts. Canopy openness increased following climber cutting, but recovered after ten months due to rapid growth of the tree canopies. Growth of regenerating seedlings, but not abundance, was favored by climber cutting. Initial cutting of climbers enhanced survival of enrichment plantings, but this benefit declined with canopy re-occupation by tree foliage. Although longer-term research is needed, cutting ruderal climbers in degraded forest remnants was shown to be a promising approach to enhance forest regeneration and carbon sequestration, justifying its consideration in the restoration agenda as a complementary activity to increasing forest cover in former agricultural lands.

A comprehensive synthesis of liana removal experiments in tropical forests

“…In a subtropical moist forest in Brazil, César et al . () reported that tree sapling biomass increased 52% after 1 yr of liana removal compared to control plots. In an experiment in a tropical dry forest in Côte d'Ivoire, Schnitzer et al .…”

Heterogenization of remaining biodiversity in fragmented tropical forests across agricultural landscapes

“…To foster and sustain biodiversity conservation in HMLs, we thus recommend: (i) effective protection of strictly Protected Areas, which usually represent the largest regional core areas (Joppa et al 2008) and where compositional shifts apparently are more stable; (ii) active restoration of forest fragments to enhance their alpha diversity, through the management of hyper abundant species ( e.g. , lianas) (César et al 2016; Estrada-Villegas & Schnitzer 2018) and reintroduction of lacking groups of species (Garcia et al 2014; Viani et al 2015) (iii) active restoration of corridors where the vegetation is degraded and natural regeneration is unlikely, aiming to enhance forest cover and connectivity among forest fragments, allowing species to disperse and persist (Howe 2014; Emer et al 2018). Finally, considering the growing development of more sustainable agricultural practices (Ferreira et al 2012, Gonthier et al 2014) and alternatives for ecological restoration with profitable purposes (Pedro H. S. Brancalion et al 2012), we encourage the establishment of policies that foster a feasible production model, aligned with the conservation of the remaining biodiversity.…”

Lianas reduce biomass accumulation in early successional tropical forests

“…For example, in a 60‐yr‐old successional forest in Central Panama, van der Heijden et al () found that lianas reduced annual biomass accumulation by 76% for trees ≥10 cm diameter. Liana‐removal experiments with saplings conducted in mid and older successional forests, or in forest gaps, have shown that biomass accumulation after liana removal can range from 52 up to 436% (Schnitzer et al , Schnitzer et al , César et al , Marshall et al ). This variability in tree response to liana removal may be due to variation in liana density and the sizes of lianas among sites, liana species and their climbing mode, different light conditions across forest ages, or the disparity in tree size classes between studies.…”