Lianas Significantly Reduce Aboveground and Belowground Carbon Storage: A Virtual Removal Experiment

Abstract

Lianas are structural parasites of trees that cause a reduction in tree growth and an increase in tree mortality. Thereby, lianas negatively impact forest carbon storage as evidenced by liana removal experiments. In this proof-of-concept study, we calibrated the Ecosystem Demography model (ED2) using 3 years of observations of net aboveground biomass (AGB) changes in control and removal plots of a liana removal experiment on Gigante Peninsula, Panama. After calibration, the model could accurately reproduce the observations of net biomass changes, the discrepancies between treatments, as well as the observed components of those changes (mortality, productivity, and growth). Simulations revealed that the long-term total (i.e., above- and belowground) carbon storage was enhanced in liana removal plots (+1.2 kgC m–2 after 3 years, +1.8 kgC m–2 after 10 years, as compared to the control plots). This difference was driven by a sharp increase in biomass of early successional trees and the slow decomposition of liana woody tissues in the removal plots. Moreover, liana removal significantly reduced the simulated heterotrophic respiration (−24%), which resulted in an average increase in net ecosystem productivity (NEP) from 0.009 to 0.075 kgC m–2 yr–1 for 10 years after liana removal. Based on the ED2 model outputs, lianas reduced gross and net primary productivity of trees by 40% and 53%, respectively, mainly through competition for light. Finally, model simulations suggested a profound impact of the liana removal on the soil carbon dynamics: the simulated metabolic litter carbon pool was systematically larger in control plots (+51% on average) as a result of higher mortality rates and faster leaf and root turnover rates. By overcoming the challenge of including lianas and depicting their effect on forest ecosystems, the calibrated version of the liana plant functional type (PFT) as incorporated in ED2 can predict the impact of liana removal at large-scale and its potential effect on long-term ecosystem carbon storage.

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

“…Climbing plants tend to proliferate extensively after disturbance and compete strongly with trees for light, water, and other resources, limiting tree growth, survival, recruitment, and aboveground biomass sequestration (Meunier, van der Heijden, et al, 2021;Schnitzer & Bongers, 2002).…”

“…Climbing plants tend to proliferate extensively after disturbance and compete strongly with trees for light, water, and other resources, limiting tree growth, survival, recruitment, and aboveground biomass sequestration (Meunier, van der Heijden, et al, 2021 ; Meunier, Verbeeck, et al, 2021 ; Schnitzer & Bongers, 2002 ). Estrada‐Villegas and Schnitzer ( 2018 ) conclude that lianas have a negative impact on all metrics of tree performance, and it has been estimated that removing climbers in tropical forests enhances tree growth up to 372%, timber yield by 1.51 m 3 per tree over 40 years, and aboveground biomass by ~76% per year compared to untreated forest (Estrada‐Villegas & Schnitzer, 2018 ; Mills et al, 2019 ; van der Heijden et al, 2015 ).…”

Reducing uncertainty of high-latitude ecosystem models through identification of key parameters

“…Through motifs, we can identify processes that become reinforced or act reinforcing and are thus more likely to cause substantial Table 1. Overview of the elements modeled in the three terrestrial biosphere models [56,57]. While TEM has two main carbon pools (soil and vegetation), they are further subdivided into leaf, wood, and root vegetation carbon, and chemically resistant soil carbon, physically resistant soil carbon, active soil carbon and coarse plant material for each soil layer, and a coarse woody debris carbon pool [58].…”

Infestação de lianas após ocorrência de incêndio florestal em uma floresta estacional semidecidual com Araucaria angustifolia (Bertol.) Kuntze

“…O acúmulo médio de biomassa das árvores foi 180% maior em clareiras nas quais as lianas foram removidas no Panamá, após oito anos, indicando que manter as lianas nas clareiras significa prejuízo para a dinâmica de carbono na floresta tanto pela redução do crescimento quanto pelo aumento da mortalidade das árvores (SCHNITZER et al, 2014b). Mais um estudo demonstrou a partir de uma simulação feita utilizando 3 anos de observações de um experimento de remoção de lianas no Panamá, que o estoque de carbono acima e abaixo do solo foi maior após a remoção de lianas (1,2 kg C m -² após 3 anos e 1,8 kg C m -² após 10 anos), houve um aumento na produtividade média líquida de 0,0009 para 0,075 kg C m -² ano -1 , 10 anos após a remoção, houve uma diminuição na produtividade primária bruta (40%) e líquida (53%) das árvores devido à competição por luz (MEUNIER et al, 2021).…”