Carbon emissions and potential emissions reductions from low-intensity selective logging in southwestern Amazonia

https://doi.org/10.1016/j.foreco.2019.02.037Get rights and content

Highlights

  • We established baselines for carbon emissions from selective logging in Peru.

  • No difference in emissions were observed between certified and uncertified concessions.

  • Despite trees with short stems and large crowns, Peru has among the lowest emissions.

  • Unintended carbon emissions could be reduced by half.

  • The majority of emissions came from the felled tree itself and very few from roads.

Abstract

Forests in southwestern Amazonia are increasingly being converted for agriculture, mining, and infrastructure development; subjected to low-intensity selective logging of high value timber species; and designated as conservation areas and indigenous reserves. To understand the impacts of forestry in this region, we evaluated carbon emissions from felling, skidding, and hauling in five FSC-certified concessions where workers were trained in reduced-impact logging (RIL) and in four non-certified concessions where workers were not trained in RIL in Madre de Dios, Peru. Emissions estimates did not differ by certification status, so we established a single baseline for selective logging emissions. Total carbon emissions from selective logging were low per hectare (4.9–11.6 Mg ha−1) due to low logging intensities (2.9–8.1 m3 ha−1). Despite the unique architecture of trees in the southwestern Amazon (short stems and large crowns), emissions per volume and per ton carbon in the extracted timber were also relatively low (1.55 Mg m−3 and 4.04 Mg Mg−1, respectively). Only emissions per area scaled with logging intensity. Emissions were dominated by the felled tree itself (in extracted logs and residuals), whereas hauling infrastructure (roads and log landings) contributed comparatively little. Unintended emissions could be reduced by 46% if concessions were able to achieve the best demonstrated outcomes in each source category and by 54% with additional improvements. Less than 5% of timber was lost due to hollow sections. We determined that it would be overly cautious to avoid cutting all trees with any hollow sections, and it would actually increase emissions per unit timber extracted if no other trees were cut in place of the hollow trees. At the tree level, certified concessions had higher log recovery and damaged fewer commercial species during felling, which should increase their current and future timber yields. It is important to both understand and improve carbon dynamics in managed forests in this emerging hotspot for greenhouse gas emissions from deforestation and forest degradation.

Introduction

Globally, approximately 11% of annual net greenhouse gas emissions and 14% of carbon emissions are from forestry and other land uses, mostly in developing tropical and subtropical countries (Goodman and Herold, 2014). Reducing tropical deforestation and degradation have long been considered important to reduce global carbon emissions, but the contribution of forest degradation has only recently been quantified over large scales (Berenguer et al., 2014, Baccini et al., 2017, Erb et al., 2017). Forest degradation reportedly accounts for one quarter (Pearson et al., 2017) to over two thirds (Baccini et al., 2017) of all forest emissions in tropical countries. In Central and South America, half (Hosonuma et al., 2012) to two thirds (Pearson et al., 2017) of degradation emissions are from logging. Both reducing carbon emissions from forestry operations and ensuring sustainability of forest management are important to address given that over half of all remaining tropical forests are dedicated to wood production (Blaser et al., 2011).

Working with forest management enterprises (e.g., concessions and community-based forest management) has the potential to improve conservation outcomes by reducing degradation through improved harvest practices and reducing deforestation by creating profitable business models based on retaining forests as forests (Griscom and Goodman, 2015). Natural forest management and avoided forest conversion are both high-potential and low-cost “natural climate solutions” to mitigate climate change (Griscom et al., 2017). At the same time, unnecessarily destructive logging is a major form of degradation that generally precedes and can even promote deforestation (Asner et al., 2006).

Due to high diversity and the marketability of timber from only a few tree species, logging in the tropics is typically selective but can nevertheless result in substantial carbon emissions. Carbon losses from selective logging come from clearing for haul roads and log yards, collateral damage around felled trees and on skid trails, crop tree residuals (i.e., branches, stumps, and sections of the stem left in the forest, etc), and the life cycle of the extracted wood itself. By employing what have become known as reduced-impact logging (RIL) practices (Putz and Pinard, 1993), these emissions can be substantially reduced (Johns et al., 1996, Pinard and Putz, 1996, West et al., 2014). Recommended RIL practices include planning harvest operations (e.g., mapping and marking commercial trees; planning roads, log yards, and skid trails; and using directional felling techniques to avoid damage to future crop trees and streams), cutting lianas on trees to be harvested at least 6 months before felling, and following guidelines on tree felling and skidding (Pinard et al., 1995, Dykstra and Heinrich, 1996). RIL guidelines typically also include practices intended to reduce the biodiversity and hydrological impacts of logging and to improve worker safety, but we here focus on only those practices likely to reduce carbon emissions (RIL-C; Griscom et al., 2014). In this study we also disregard the substantial post-logging carbon benefits of RIL such as increased rates of carbon stock recovery (Lincoln, 2008, Vidal et al., 2016).

Despite the large amount of research conducted on RIL across the tropics (FAO, 2004), we are aware of no studies on RIL in Peru. Given that logging contributes substantially to Peru’s carbon emissions, which the country has committed to reduce (MINAM, 2015), we conducted this study to establish a baseline from which improvements can be measured. Furthermore, while Peru is globally known for its deforestation (Asner et al., 2010, Hansen et al., 2013, Robiglio et al., 2014) and problems with illegal logging (Gutierrez-Velez and MacDicken, 2008, Finer et al., 2014), the country also hosts efforts to improve forest management practices that deserve attention.

Among the interventions intended to promote responsible forest management in general and RIL in particular, Forest Stewardship Council (FSC) certification looms large. Since its founding in 1993, numerous studies reported on FSC’s impacts but few were designed to avoid positive selection biases, ignored contextual changes of likely importance, and suffered from other deficiencies such as small sample sizes (Romero et al., 2017, Komives et al., 2018). In a meta-analysis of this literature, Blackman et al. (2017) found no conclusive evidence that forest certification has positive environmental outcomes. In another meta-analysis that disregarded the quality of the included studies, Burivalova et al. (2017) reported that the environmental outcomes from certified and RIL forest management (including C emissions) were better than conventional management in 76% of case studies (worse in 6% and no difference in 18%). However, this and other studies also concluded that the benefits of RIL decline when logging intensity is taken into account because certified concessions and those that claim to employ RIL practices tend to harvest at lower intensities than their uncertified and conventionally logged counterparts (Medjibe et al., 2013, Griscom et al., 2014, Martin et al., 2015, Burivalova et al., 2017).

The Peruvian Amazon is an important focal geography where many global issues are currently at play. Peru has fourth highest area of forest cover in tropics, and nearly half of the country’s 68 million ha are classified as permanent production forest (Blaser et al., 2011). The southwestern Amazon and specifically the MAP region (Madre de Dios, Peru–Acre, Brazil–Pando, Bolivia) is undergoing rapid deforestation and forest degradation following completion of the Interoceanic Highway (Baraloto et al., 2015, Alarcón et al., 2016), and deforestation and degradation of natural forests represents almost half of Peru’s greenhouse gas emissions (MINAM, 2013). Legal and illegal logging has already degraded much of the natural forest in the Peruvian Amazon (Asner et al., 2010), and the legal timber industry is expanding (Cossio et al., 2014).

We employed the methods of Griscom et al. (2014) to estimate carbon emissions from forestry concessions in Madre de Dios, Peru. Specifically, our objectives were to: (i) establish a baseline for carbon emissions from selective logging in the region; (ii) assess whether RIL training associated with FSC certification reduced carbon emissions; and (iii) estimate potential emissions reductions through RIL-C. Because of the low logging intensity (Cossio et al., 2014) and distinctive architecture of trees in southern Peruvian forests (relatively short stems and large crowns; Goodman et al., 2014), we hypothesized baseline emissions per ha to be lower and emissions per unit timber extracted to be higher than the tropical average. As field staff in all certified concessions were trained in RIL while those employed by non-certified concessions were not, we expected emissions from certified concessions to be lower while fully recognizing that any differences cannot be attributed to certification due to other differences among the concessions and lack of a counterfactual design.

Section snippets

Site and socio-economic description

Our study was conducted within Tahuamanu Province of Madre de Dios, Peru. Forests here are broadly classified as lowland, moist, terra firme forest (Whitmore, 1998, Achard et al., 2002), and “bamboo-dominated” forests are common in this region (Carvalho et al., 2013). Mean annual temperature is 24.5 °C; mean annual precipitation is 1811 mm with a 3–4 month dry season (Hijmans et al., 2005). The area is relatively flat with medium gradient hills and elevation ca. 250–375 masl (FAO et al., 1998).

Logging practices

All FMUs were logged at low intensities (2.9–8.1 m3 ha−1) and harvested only 15–62% of government-authorized volumes (Table 2). All five certified FMUs harvested at lower intensities than the four non-certified FMUs in terms of trees (p = 0.045) and volumes (p = 0.017) per ha. Felled trees were on average 101.8 (standard error 2.3) cm dbh and 38.6 (0.6) m tall. Mean extracted logs were 15.6 (0.3) m long, 11.3 (0.6) m3, and 4.3 (0.3) Mg C. Certified concessions were much larger than

Logging practices and emissions baselines

Harvest intensities for all concessions in our study were much lower than reported for other tropical forests, with the exception of other parts of the southwestern Amazon (Rutishauser et al., 2015) and Gabon (Medjibe et al., 2013). As found elsewhere (e.g., Blackman et al., 2018), certified concessions were much larger than non-certified concessions, which is no surprise given that the costs of certification (Ruslandi et al., 2014) would be prohibitive for small concessions.

Like prior studies,

Conclusions and recommendations

From a carbon perspective, Madre de Dios in the southwestern Amazon has among the best carbon outcomes from selective logging of all tropical countries studied. Nonetheless, three times more carbon is emitted from logging operations than is extracted, and this amount could be reduced by half through RIL-C harvesting practices. FSC certification was not created specifically to reduce carbon emissions, and we find little evidence that it does so in Peru. We call for a clearer link between

Acknowledgements

We thank our forestry technicians and research assistants, Robert Nishida, Nilton Martinez, and Angel Balarezo for their hard work. Fieldwork was supported by WWF–Peru, and we thank Cecilia Alvarez, Rafael Venegas, Juan Carlos Riveros, Karen Mo, Alonso Gonzales, and Karina Salas for coordination of field activities. RCG and MHA were funded by WWF-Peru during the field campaign. All analysis, interpretation, and preparation of the manuscript were conducted independently.

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