Reduced-impact logging in Borneo to minimize carbon emissions and impacts on sensitive habitats while maintaining timber yields
Introduction
Tropical and subtropical countries emit an estimated 0.85 GtCO2 yr−1 from selective harvests of timber from natural forests (Ellis et al. this issue), equivalent to direct emissions from commercial buildings globally (Lucon et al., 2014), and ¼ of average annual emissions from tropical forest cover loss since 2001 (Gibbs et al., 2018). At least 39 tropical countries report plans to reduce these emissions in their Nationally Determined Contribution (NDC) to the United Nations Framework Convention on Climate Change Paris Agreement (Ellis et al. this issue). One of these countries, Indonesia, is considering a national regulation that requires reduced impact logging for climate mitigation, or RIL-C, as part of fulfilling their NDC to the Paris Climate Agreement. Ideally, RIL-C can be implemented while also delivering explicit biodiversity and other conservation outcomes to which Indonesia committed to under the Convention on Biological Diversity.
Studies on tropical forestry over the past decades reported that reduced-impact logging (RIL) in experimental cutting blocks reduced emissions from logging by 30–50% (Johns et al., 1996, Mazzei et al., 2010, Medjibe et al., 2013, Pinard and Putz, 1996, Vidal et al., 2016). Given the experimental nature of these studies, it remains unclear whether these levels of emission reductions can be realized and verified at operational scales, and what individual RIL interventions should be prioritized to achieve these results. More fundamentally, there is evidence that emissions benefits of some attempts at RIL disappear when logging intensities are taken into account (Sist et al., 2003, Martin et al., 2015). It is also not clear whether the potential climate mitigation benefits of RIL are associated with forest certification (Griscom et al., 2014, Martin et al., 2015, Miller et al., 2011), which may reflect that certification systems, such as the Forest Stewardship Council (FSC), while requiring that many RIL practices are employed, were not designed to achieve or verify emissions reductions (Romero and Putz, 2018).
Confusion about the scalable and verifiable climate benefits of RIL motivated development of RIL-C, a set of improved selective logging practices focused on verifiable emission reductions (Griscom et al., 2014). RIL-C accounting methodologies, for example, differ from prior RIL standards in emphasizing the avoidance of felling trees that are subsequently not harvested due to the presence of hollows in their stem. RIL addresses a broader set of issues beyond carbon emissions that are not considered by RIL-C, such as minimizing erosion, set asides for biodiversity conservation, and worker safety. Neither RIL-C or RIL address other dimensions of improved natural forest management (NFM) such as sustainable silvicultural practices, social equity, milling practices, and other aspects of biodiversity conservation (Fig. 1).
Here we propose a set of RIL-C practices, and aligned RIL set asides, for East and North Kalimantan. We estimate the potential of individual RIL-C practices to reduce carbon emissions, and we extrapolated carbon benefits across natural timber production forests in Indonesia. We consider the potential to achieve additional non-carbon conservation outcomes, in particular biodiversity and hydrology, that could accompany implementation of RIL-C practices by improved spatial planning of areas set aside from logging.
We focus on RIL-C outcomes that can be verified by or are consistent with a new methodology designed to account for climate benefits (The Nature Conservancy and TerraCarbon LLC, 2016). This methodology uses the same field data employed here to establish a regional emissions baseline for East and North Kalimantan, from which emissions reductions can be achieved through the four RIL-C practices to be described here. The methodology establishes “impact parameters” for each RIL-C practice that allow efficient and robust field verification of logging impacts. Crediting of emissions reductions are restricted to legally authorized concessions on previously logged forests.
We limit our analysis to discrete RIL-C practices that have measurable carbon emissions reductions associated with explicit and feasible improvements in practices, and that do not change timber yields. These constraints allow for commercially viable scaling of RIL-C practices as contributions to achievement of national emissions reductions goals without displacing demand for timber elsewhere (i.e., leakage) and/or promoting the substitution of wood products by high-carbon emission materials such as concrete, steel, or aluminum (Oliver et al., 2014).
The effects of selective logging in tropical forests on carbon, biodiversity, and other ecosystem services vary with harvest intensities, practices employed, and spatial distributions of impacts (Burivalova et al., 2014, Griscom et al., 2018). A study in East and North Kalimantan reported that on average over one third of harvest block areas are not actually logged under conventional practices but that the unlogged areas did not occur in low stand volume areas, nor were they concentrated in ecologically sensitive areas (Ellis et al., 2016). This finding presents the opportunity to reduce the deleterious impacts of logging on biodiversity and hydrology by setting aside sensitive riparian and steep slope areas without reducing timber yields. Set asides could be established along riparian buffer zones, given their importance for wildlife as well as for the integrity of freshwater ecosystems, downstream water quality, and attenuation of peak flows. Set asides might also be designated in areas with steep slopes, which are prone to excessive soil disturbances associated with skidding, with attendant increases in erosion and reductions in site productivity (Putz et al., 2018, Sidle et al., 2004). We include here an analysis of improved set aside planning that can happen in tandem with RIL-C efficiency practices that do not adjust harvest intensity and timber volume extracted.
Section snippets
Study sites and field measurements
We carried out field surveys in nine logging concessions selected in a stratified random manner in dipterocarp forests of East and North Kalimantan, Indonesia (Fig. 2). To stratify the samples, we conducted a cluster analysis of all the major timber concessions in the region using Wards Linkage Euclidian distance. We identified three clusters (dark grey areas in Fig. 1) based on slope, elevation, percent cover by each of three major soil types (Inceptisols, Oxisols, Ultisols), distance from the
Definition of Level 1 and Level 2 RIL-C implementation
We found no clear relationship between concession cluster membership and logging emissions. The cluster of more remote high elevation concessions (A, D, F) had a wide range of logging emissions levels, overlapping with emissions levels for lower elevation least remote concessions (E, G, H) and intermediate concessions (B, C, I). The nine sampled concessions differed substantially in existing emissions associated with each of the four logging practices, but no one concession was the “leader” for
Conclusions
One third of emissions from logging can be avoided without reducing timber yields if logging concessionaires implement RIL-C practices at levels already demonstrated by the best performing commercial operators (Level 1). Although we believe that this level of emissions reductions could be achieved at low cost or cost savings, evidence in support of this assumption is mixed (Medjibe and Putz, 2012). Level 1 RIL-C practices require no changes in machinery, but do require training in improved
Acknowledgements
We thank staff of The Nature Conservancy and the Ministry of Forestry of Indonesia who provided essential in country support for this work including Oman Aliman, Lenny Christy, Mohammed Fajri, Herlina Hartanto, Fatmi Noor'an, Purnomo, Ingnatius Putu, Adjie Rachmad, Saipul Rahman, Ali Sasmirul, Sugy Sudiyanto, Umbar Sujoko, Alie Syopyan, Bambang Wahyudi, Wahjudi Wardojo, and Iwied Wahyulianto. We thank all members of the SNAPP Forest Sharing vs Sparing Working Group and Trisha Gopalakrishna for
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