Elsevier

Forest Ecology and Management

Volume 356, 15 November 2015, Pages 224-233
Forest Ecology and Management

Impacts of tropical selective logging on carbon storage and tree species richness: A meta-analysis

https://doi.org/10.1016/j.foreco.2015.07.010Get rights and content

Highlights

  • We undertook a meta-analysis to assess impacts of tropical selective logging.

  • This focused on stand damage, aboveground biomass and tree species richness.

  • Higher logging intensity increased damage, and reduced biomass and species richness.

  • Reduced impact logging reduces damage, this was not true for biomass or richness.

  • More research is needed to determine impact of reduced impact logging on carbon.

Abstract

Over 400 million hectares of tropical forest are currently designated as logging concessions. This practice is an important source of timber, but there are concerns about its long-term sustainability and impacts on biodiversity and carbon storage. However, logging impacts vary widely, making generalisation and, consequently, policy implementation, difficult. Recent syntheses of animal biodiversity have indicated that differences in logging intensity – the volume of wood removed ha1 – might help to explain some of these disparities. In addition, it has widely been assumed that reduced impact logging (RIL) might minimise some of the negative effects of logging; though in practice, this has rarely been tested. To test the hypothesis that RIL reduces negative impacts of selective logging once intensity is controlled for, we used meta-analyses of selective logging impact studies, focusing specifically on (1) residual tree damage, (2) aboveground biomass and (3) tree species richness. Our results indicate that RIL appears to reduce residual tree damage when compared to conventional methods. However, changes in aboveground biomass were negatively related to logging intensity. Any effect of RIL, independent of logging intensity, was difficult to discern since it was carried out at relatively low intensities. Tree richness appeared to increase at low intensities but decreased at higher intensities and any effect of RIL was difficult to detect. Our results tentatively support the hypothesis that RIL reduces the negative impacts of logging on tree damage, but do not support suggestions that RIL reduces loss of aboveground biomass or tree species richness. However, this lack of support may be a result of the relative paucity of data on the topic. Based on our results, we suggest that better evidence is needed to assess the differences between the impacts of RIL and conventional logging. Studies that consider plot-level differences in logging intensity are required to fill this knowledge gap. In addition, there must be clarification of whether RIL is an inherently low intensity practice so that this can be factored into management.

Introduction

Over 400 million hectares of tropical forest are designated as timber concessions, making selective logging – the removal of selected trees from a stand – one of the most widespread human disturbances in tropical forests (Asner et al., 2009). Tropical logging produces approximately one eighth of global timber (Blaser et al., 2011), and is an important contributor to many local and national economies. However, logging can have negative impacts on biodiversity (Berry et al., 2010) and leads to increased carbon emissions (Bryan et al., 2010, Nepstad et al., 1999). Poor management of logging concessions can endanger the long-term sustainability of timber production and there have been suggestions that we might be approaching peak timber production in the tropics (Shearman et al., 2012).

Given the large global demand for tropical timber, researchers have proposed modifications to logging techniques to reduce their negative environmental effects, particularly regarding carbon emissions (Putz et al., 2008b) and their impacts on biodiversity (Bicknell et al., 2015). The direct impacts of selective logging are largely the result of the effects of harvesting, skidding of logs, and construction of infrastructure, such as roads, on the mortality and recruitment of trees. The major source of carbon losses is the felling of large trees. However, damage and subsequent death of smaller trees as a result of crushing by felled trees or damage during removal of logs can also be a major contributor of carbon emissions (Putz et al., 2008b). Damage and mortality of non-target trees can also limit forest recovery (Gourlet-Fleury et al., 2013b, Sist et al., 2014) and, if recruitment fails to keep pace with mortality, this can result in altered tree community composition (Ouédraogo et al., 2011). Some of the negative effects of logging on carbon emissions and biodiversity could potentially be minimised by reducing large tree mortality, reducing residual damage to trees that are not felled, or increasing the recruitment of priority species.

One of the most widely accepted means of reducing large tree mortality is to limit the minimum diameter at breast height (DBH) at which trees can be cut (Sist et al., 2003a). Placing such limits decreases logging intensity (volume of trees extracted ha1). In addition to reducing the number of large trees felled, limiting logging intensity can also reduce residual damage to unfelled trees (Mazzei et al., 2010, Picard et al., 2012). In terms of biodiversity, recent work has shown that increases in logging intensity leads to a linear reduction in animal species richness for most vertebrates while a slight increase in bird species richness is observed at low intensities (Burivalova et al., 2014). Similarly, it is likely that species richness of trees might be enhanced at low intensities owing to an influx of shade intolerant species as suggested by the intermediate disturbance hypothesis (Bongers et al., 2009; but see Fox, 2013 for a full discussion of the intermediate disturbance hypothesis).

In recent years reduced impact logging (RIL) techniques have been considered to reduce the negative environmental impacts of selective logging (Putz et al., 2008a). Though application of RIL is not uniform, it tends to involve one or more of the following activities: cutting lianas prior to logging, felling trees in predetermined directions to minimise the impact to the surrounding forest, limiting road construction, identification and mapping of trees to be cut prior to logging, and planning of roads and skid trails (Pinard and Putz, 1996). Individual studies have suggested that RIL might reduce carbon emissions (Pinard and Putz, 1996), residual tree damage (Sist et al., 2003c), and result in more favourable biodiversity outcomes (Bicknell et al., 2014) when compared to conventional logging. It has also been suggested that RIL could be carried out at similar intensities to conventional logging while causing less damage to residual trees (Pinard and Putz, 1996, Putz et al., 2001; but see Sist et al., 2003a, Sist et al., 2003b, Sist et al., 2003c). Furthermore, it has been proposed that its wide implementation could reduce global carbon emissions from selective logging by 30% (Putz et al., 2008b). If true, these minimisations in the negative consequences of selective logging could be vital in securing long-term sustainability of timber producing tropical forests.

Despite claims made about the benefits of RIL, evidence is conflicting. Studies that investigate the effectiveness of RIL in reducing the negative impacts of conventional logging generally do so by comparing between areas logged using RIL techniques at relatively low intensities. For example, in one of the few studies comparing the effects of RIL and conventional logging on carbon stocks, any treatment effect was confounded by an approximately 50% higher logging intensity in conventionally logged plots (Pinard and Putz, 1996). Moreover, in the studies where differences in the logging intensity have been controlled for, there appears to be little difference in the impacts of RIL on the damage to residual trees (Sist et al., 2003c) and carbon stocks (Griscom et al., 2014). Taken together, these observations bring the value of RIL into question, given that a major aim of RIL is to reduce impact whilst maintaining timber yields (Keller et al., 2003).

Though RIL is widely cited as a method for limiting the negative effects of tropical selective logging there is little information regarding its general impact once logging intensities are controlled for. Though Putz et al. (2012) provided a valuable overview of the impacts of tropical selective logging on biomass and tree species richness, no attempt was made to explain differences in these impacts between sites. The recent meta-analysis by Bicknell et al. (2014) indicated that RIL reduced impacts on animal populations, but there are no equivalent syntheses of effects on trees. Given that REDD+ aims to provide economic incentives to reduce loss of carbon and biodiversity from forests (Harvey et al., 2010) and RIL has been suggested as means of attaining these reductions (Putz et al., 2008b), understanding variation in logging impacts is vital to inform management. In this study, we aim to address this knowledge gap by conducting a meta-analysis to determine which factors relating to logging method and intensity might explain differences in (1) residual stand damage, (2) aboveground biomass loss, and (3) tree species richness.

Section snippets

Systematic review

We defined selectively logged tropical forests as native forests between the latitudes of 40′N and 40′S subjected to selective tree removal for timber. We undertook a standard systematic review as described by Pullin and Stewart (2006) and used the terms (“biomass” OR “carbon” OR “basal area” OR “damage” OR “snag” OR “non-target” OR “tree” OR “species richness” OR biodiversity) AND (selective logg OR felling OR timber extraction OR reduced-impact logging OR degradation) AND “tropical forest”

Results

The systematic review yielded 62 studies, from which we extracted data on residual tree damage from 72 sites, and 43 and 23 paired, replicated sites that measured biomass and tree species richness respectively. In total these data comprised of information on residual damage from 285 plots, comparisons of aboveground biomass from 326 logged and 128 unlogged plots and comparisons of tree species richness from 256 different logged and 161 unlogged plots. Median logged-site age for those sites

Discussion

This study draws on a larger body of evidence than the recent meta-analysis of Putz et al. (2012) on the impacts of selective tropical logging, making it the most precise meta-analysis of the impacts of tropical selective logging on carbon and tree biodiversity to date. In addition, our analyses of the impacts of logging on biomass and species richness accounted for (i) differences in study precision, (ii) study-level pseudoreplication, and (iii) explored the reasons for variation in impacts

Acknowledgements

PM would like to thank NERC for providing PhD funding. MP and MSK thank Sime Darby for funding of the SAFE project. This paper is a contribution to Imperial College’s Grand Challenges in Ecosystems and the Environment initiative. Thanks are due to Louise Barwell for statistical advice and to anonymous reviewers of a previous version of this manuscript.

References (85)

  • D.-Y. Ouédraogo et al.

    Thinning after selective logging facilitates floristic composition recovery in a tropical rain forest of Central Africa

    For. Ecol. Manage.

    (2011)
  • S.N. Panfil et al.

    Short term impacts of experimental timber harvest intensity on forest structure and composition in the Chimanes Forest

    Bolivia

    (1998)
  • M. Peña-Claros et al.

    Beyond reduced-impact logging: Silvicultural treatments to increase growth rates of tropical trees

    For. Ecol. Manage.

    (2008)
  • M. Peña-Claros et al.

    Regeneration of commercial tree species following silvicultural treatments in a moist tropical forest

    For. Ecol. Manage.

    (2008)
  • R. Pereira et al.

    Forest canopy damage and recovery in reduced-impact and conventional selective logging in eastern Para, Brazil

    For. Ecol. Manage.

    (2002)
  • F.E. Putz et al.

    Reduced-impact logging: challenges and opportunities

    For. Ecol. Manage.

    (2008)
  • C.A. Rockwell et al.

    Forest ecology and management logging in bamboo-dominated forests in southwestern Amazonia: caveats and opportunities for smallholder forest management

    For. Ecol. Manage.

    (2014)
  • P. Shearman et al.

    Are we approaching “peak timber” in the tropics?

    Biol. Conserv.

    (2012)
  • P. Sist et al.

    Large trees as key elements of carbon storage and dynamics after selective logging in the Eastern Amazon

    For. Ecol. Manage.

    (2014)
  • P. Sist et al.

    Harvesting intensity versus sustainability in Indonesia

    For. Ecol. Manage.

    (1998)
  • P. Sist et al.

    Reduced-impact logging in Indonesian Borneo: some results confirming the need for new silvicultural prescriptions

    For. Ecol. Manage.

    (2003)
  • H. Tangki et al.

    Biomass variation across selectively logged forest within a 225-km2 region of Borneo and its prediction by Landsat TM

    For. Ecol. Manage.

    (2008)
  • T.A.P.P. West et al.

    Forest biomass recovery after conventional and reduced-impact logging in Amazonian Brazil

    For. Ecol. Manage.

    (2014)
  • G.P. Asner et al.

    A contemporary assessment of change in humid tropical forests

    Conserv. Biol.

    (2009)
  • C. Baraloto et al.

    Contrasting taxonomic and functional responses of a tropical tree community to selective logging

    J. Appl. Ecol.

    (2012)
  • Barton, K., 2014. MuMIn: Multi-model...
  • D. Bates et al.

    lme4: Linear mixed-effects models using Eigen and S4

    ArXiv

    (2014)
  • N.J. Berry et al.

    The high value of logged tropical forests: lessons from northern Borneo

    Biodivers. Conserv.

    (2010)
  • N.J. Berry et al.

    Impacts of selective logging on tree diversity across a rainforest landscape: the importance of spatial scale

    Landsc. Ecol.

    (2008)
  • J.E. Bicknell et al.

    Reconciling timber extraction with biodiversity conservation in tropical forests using reduced-impact logging

    J. Appl. Ecol.

    (2015)
  • J.E. Bicknell et al.

    Improved timber harvest techniques maintain biodiversity in tropical forests

    Curr. Biol.

    (2014)
  • J. Blaser et al.

    Status of Tropical Forest Management 2011. ITTO Technical Series No 38

    (2011)
  • F. Bongers et al.

    The intermediate disturbance hypothesis applies to tropical forests, but disturbance contributes little to tree diversity

    Ecol. Lett.

    (2009)
  • M. Borenstein et al.

    Introduction to Meta-Analysis

    (2009)
  • J. Bryan et al.

    Impact of logging on aboveground biomass stocks in lowland rain forest, Papua New Guinea

    Ecol. Appl.

    (2010)
  • T.B.a. Burghouts et al.

    Effects of tree species heterogeneity on leaf fall in primary and logged dipterocarp forest in the Ulu Segama Forest Reserve, Sabah, Malaysia

    J. Trop. Ecol.

    (1994)
  • K.P. Burnham et al.

    AIC model selection and multimodel inference in behavioral ecology: some background, observations, and comparisons

    Behav. Ecol. Sociobiol.

    (2011)
  • C. Cannon et al.

    Tree species diversity in commercially logged bornean rainforest

    Science

    (1998)
  • G. Carreño-Rocabado et al.

    Effects of disturbance intensity on species and functional diversity in a tropical forest

    J. Ecol.

    (2012)
  • J.H. Connell

    Diversity in tropical rain forests and coral reefs

    Science (80-.).

    (1978)
  • D.P. Edwards et al.

    Land-sharing versus land-sparing logging: Reconciling timber extraction with biodiversity conservation

    Glob. Chang. Biol.

    (2014)
  • G.M. Foody et al.

    Tree biodiversity in protected and logged Bornean tropical rain forests and its measurement by satellite remote sensing

    J. Biogeogr.

    (2003)
  • Cited by (87)

    • Effects of sustainable forest management on tree diversity, timber volumes, and carbon stocks in an ecotone forest in the northern Brazilian Amazon

      2022, Land Use Policy
      Citation Excerpt :

      Currently, SFM programs have been facing questions regarding their true sustainability and the applicability of the legal criteria adopted in Brazilian Amazon (MMA, 2009; BRASIL, 2006; IBAMA, 2007; CONAMA, 2009; BRASIL, 2012) related to the timing of cutting cycles (in years) for different species (Schӧngart, 2008), selective logging intensity (m³/ha) (Johns et al., 1998; Pereira et al., 2002; Holmes et al., 2002), minimum diameter cutting limits (DCL) (Gourlet-Fleury et al., 2005) or minimum cutting diameters (MCD) (Dauber et al., 2005; Vinson et al., 2015), silvicultural treatments, control of remaining forest stocks, conservation versus extinction of forest species, specific volumetric equations (Higuchi et al., 2015; Gimenez et al., 2015), ecology and regeneration requirements, and the need for greater numbers of permanent plots and continuous monitoring of forest inventories (CFIs) that could validate and support current environmental legislation. Selective logging (SL) contributes to almost 15% of global timber yields (Martin et al., 2015; Poudyal et al., 2018). However, due to wide variations in the effective application of SFM concepts as a result of political and market pressures (in terms of different approaches and techniques for forest harvesting, site specific cultures, and varying levels of access to tools and technologies), its policies and practices are being questioned in regards to their ability to ensure the true sustainability of global forest benefits (Brandt et al., 2016; Poudyal et al., 2020).

    View all citing articles on Scopus

    This article is part of a special feature entitled “The characteristics, impacts and management of forest fire in China”

    View full text