Actively Restoring Resilience in Selectively Logged Tropical Forests

Received: 28 February 2018 | Accepted: 19 July 2018 DOI: 10.1111/1365-2664.13262

REVIEW

Actively restoring resilience in selectively logged tropical forests

Gianluca R. Cerullo | David P. Edwards

Department of Animal and Plant Sciences, University of Sheffield, Sheffield, Abstract UK 1. Huge tracts of tropical forest are selectively logged. Meanwhile, emerging global

Correspondence agendas are providing unprecedented incentives for large-scale restoration within Gianluca Rocco Cerullo human-impacted tropical forest landscapes. Whilst logged forests have high con- Email: [email protected] servation value, their adoption within these agendas remains controversial. Handling Editor: Jennifer Firn 2. We review the value of restoring logged tropical forests for boosting economic and environmental resilience. Targeted interventions can recover depleted timber stocks, increase saleable carbon stores, and deliver employment and non-timber forest products (NTFPs) to local communities. Restoration has mixed outcomes for biodiversity but if it improves relogging practices and protects forests from conversion to agricultural plantations may have major positive impacts. 3. We also examine socio-economic and political pathways for upscaling logged forest restoration and their incorporation into sustainable forestry, given political and commercial malaise on post-logging interventions. Spurring these transitions will require strong institutions, executed by policies that enable long-term concession licences and community land tenure, that leverage commercial involvement and payments for ecosystem services, and that optimise existing interventions. 4. Research frontiers include: (a) validating the economic and technical feasibility of different interventions; (b) understanding how these interventions impact on synergies and trade-offs between ecosystem services, NTFPs, and biodiversity; and (c) identifying when to restore a logged forest. This requires establishing long- term experimental trials that jointly track environmental and socioeconomic outcomes. 5. Synthesis and applications. Post-logging interventions can deliver various timber, carbon, socioeconomic and potentially biodiversity benefits but are underem- ployed and undervalued pantropically. Opportunities exist to optimise interventions by tailoring incentives, policies, and management to ecological and social circumstances. Governments, conservation bodies and the private sector must underscore restoration of production forests as a major future objective, including via greater adoption in global initiatives, including forest and landscape restoration under the Bonn Challenge and the Reducing Emissions from Deforestation and Forest Degradation (REDD+) agenda.

J Appl Ecol. 2019;56:107–118. wileyonlinelibrary.com/journal/jpe © 2018 The Authors. Journal of Applied Ecology | 107 © 2018 British Ecological Society 108 | Journal of Applied Ecology CERULLO and EDWARDS

KEYWORDS biodiversity, climber cutting, enrichment planting, logged tropical forest, REDD+, restoration, selective logging, silviculture

1 | INTRODUCTION hectares of degraded ecosystems by 2020 and 350 million hectares by 2030 (Bonn Challenge, 2018). Bolstered by a suite of additional Human activities have overtaken natural forces, like hurricanes and programs and the potential emergence of billion-dollar carbon mar- wildfires, as dominant drivers of tropical forest disturbance (Lewis, kets, there is now unprecedented impetus for large-scale restoration Edwards, & Galbraith, 2015). Selective logging is the most prevalent of human-impacted tropical forests (Aronson & Alexander, 2013). of these disturbances. Over a fifth of tropical forests were selec- Here, we explore the role of post-logging interventions in recov- tively logged between 2000 and 2005 (Asner, Rudel, Aide, Defries, ering timber stocks and biodiversity, providing climate change miti- & Emerson, 2009) and an area approximately twice the size of gation, non-timber forest products (NTFPs) and social benefits. We Greenland (400 million hectares) is currently designated as produc- find theory suggesting that these added values can hinder the con- tion forest globally (Blaser, Sarre, Poore, & Johnson, 2011). version of logged forest. Unfortunately, the benefits of post-logging Logging is environmentally harmful, driving declines in interior interventions are often underappreciated and are rarely employed at forest wildlife and carbon stocks, and bisecting forests with road scale. We thus explore ways for operationalising and incorporating networks that facilitate incursion by poachers and illegal loggers restoration activities within logged-over forest and identify crucial (Edwards, Tobias, Sheil, Meijaard, & Laurance, 2014). Yet regener- avenues for future inquiry. ating logged forests retain high conservation value, preserving most biodiversity and ecological processes, and continuing to store and sequester carbon, regulate climate and maintain large-scale hydro- 2 | INTERVENTION GOALS WITHIN logical processes (Edwards, Tobias, et al., 2014), particularly in com- SELECTIVELY LOGGED FORESTS parison with the agricultural lands often replacing them (Gaveau et al., 2016). Different reasons for logged forest interventions exist, warranting A global restoration agenda is emerging as a key way of en- different activities (Table 1). Importantly, the type of intervention hancing the recovery of ecosystem services and biodiversity in employed will track closely the form of management that logged for- human-impacted tropical forest landscapes (Brancalion et al., 2017). ests falls under (Table 1). Thus, “ecosystem restoration” will be most International initiatives, like the Bonn Challenge and New York suitable in exhausted timber concessions or within protected area Declaration, have garnered astonishing political traction with over frameworks, “timber enhancement” best within actively managed 40 countries and institutions committed to recovering 150 million permanent timber estate, and “ecosystem service enhancement”

TABLE 1 A summary of the diverse objectives that might drive post-logging interventions

Intervention type Main objective Potential activities

Ecosystem restoration Recover the structural complexity, biodiversity, Protect forests from further logging and allow natural and ecosystem functions and services present regeneration in old-growth forest Restore logging-damaged habitat features like streams and rare microhabitats Assist natural succession by liberating seedlings from outcompeting pioneers or lianas Plant a wide range of species, including those of wildlife importance (e.g. fruit trees, habitat-providing and rare species) or resilient to shifts under projected climate regimes Timber enhancement Recover timber stocks between logging Liberate understorey timber seedlings from competing pioneer rotations to ensure a sustainable yield of trees or lianas merchantable timber Plant and tend a small number of merchantable timber species, including those valuable species found at low-density Carbon enhancement Recover carbon stocks Liberate trees with the highest carbon sequestration potential. Enrichment planting Ecosystem service Maintain or recover a range of ecosystem Planting or tending of species providing timber and non-timber enhancement services important for communities and forest products. Restoration to mitigate for poor logging enhance the flow of forest products of practices: e.g. planting on over-logged steep slopes to livelihood importance improve hydrological processes CERULLO and EDWARDS Journal of Applied Ecolog y | 109 optimal wherever production forests are managed or depended Where logged forests lack sufficient commercial seedlings, en- upon by rural communities. Additionally, “carbon enhancement” is richment planting may be warranted (Sasaki et al., 2011). One op- appropriate wherever interventions increase emissions-capture ver- tion is planting seedlings within logging gaps; commercial-scale sus business-as-usual management, meaning activities could target planting of the native fast-growing tree Schizolobium parahyba in the forests either historically or actively managed for timber. Amazon is an innovative example. Within 13 years, this species can Another goal of post-logging interventions may be averting con- be grown and processed into plywood, generating revenue whilst version to other land-uses. Across 40 years in Malaysian Borneo, slow-growing timber species replenish (Schwartz, Pereira, Siviero, 57%–60% of old-growth and selectively logged forest loss was & Yared, 2017). Another option is planting species along cleared linked with conversion to industrial oil-palm and pulpwood planta- lines. Legislation in Indonesia calling for silvicultural intensification tion (Gaveau et al., 2016), whilst ~33 million hectares of Indonesian within ~65 million hectares of natural forest could see this method production forest was recently omitted from a major Reducing widely applied, generating high timber yields (Ruslandi, Cropper, & Emissions from Deforestation and Forest Degradation (REDD+) Putz, 2017). Line planting of dipterocarps within twice-logged forest initiative with Norway, rendering them vulnerable to conversion recovers merchantable timber stocks equivalent to primary forest (Sloan, Edwards, & Laurance, 2012). If interventions occur within within 40 years; comparable naturally regenerating forests recover well-managed forests, this may lower risk of conversion. Between below half of this volume after 60 years (Figure 1a). Moreover, within 2000 and 2010, permanent timber concessions in Indonesia that twice-logged forest, timber enhancement is projected to yield a net avoided government reclassification to plantations suffered indistin- present value three times greater than natural regeneration alone (at guishable deforestation rates from protected areas (Gaveau et al., <6% annual discount rate, Ruslandi, Romero, & Putz, 2017). 2013). According to the objective, economic or environmental benefits of post-logging interventions can accrue to a variety of factors, 3.2 | Climate change mitigation including logging companies and governments (via timber enhancement) or global communities (via carbon enhancement, limiting Annually, around 1 billion tons of CO2 is released from tropical tim- global warming to 2°C increase). ber harvesting (Pearson, Brown, Murray, & Sidman, 2017). Yet despite the large carbon footprint of timber extraction, ceasing logging operations is not necessarily optimal for reducing greenhouse emis- 3 | IMPACTS OF POST-LOGGING sions, as market forces could drive the substitution of low-energy INTERVENTIONS building wood with high-energy construction alternatives, like steel (Oliver, Nassar, Lippke, & McCarter, 2013). Instead, strategic inter- 3.1 | Timber recovery ventions can enhance carbon profiles in production forest. Repeated logging cuts the economic value of standing forest by Lianas reduce large tree carbon stocks by up to 50% (Durán depleting timber reserves. On average, 54% of timber volume ex- & Ernasto, 2013). Correspondingly, since large trees dispropor- tracted during the first cutting cycle is available at the second, with tionately store carbon in tropical forests, their increased growth this varying enormously according to logging intensity, technique following liana and pioneer removal directly increases carbon se- and commercial species ecology (Putz et al., 2012). Reduced-impact questration (Villegas et al., 2009). Over 24 years in the Central logging (RIL) reduces collateral tree damage during timber extraction, African Republic, post-logging thinning of pioneer species fostered whereas increasing the recovery period between logging events and a near-doubling of aboveground biomass compared to naturally re- reducing overall timber extraction can further sustain yields (Sist, generating logged forests (Figure 1b). Such activities can provide Picard, & Gourlet-Fleury, 2003). These activities, however, are often cost-effective carbon sequestration, since the expenses of raising insufficient to maintain timber yields under economically attractive and planting seedlings are avoided. In Bolivia, girdling compet- cutting cycles, so tropical foresters have long examined methods ing trees costs as little as $5.08 per hectare (Sasaki et al., 2011). of speeding merchantable timber species recovery through post- Enrichment planting also increases carbon sequestration albeit at logging interventions. Theoretically, post-logging interventions that greater expense. After 60 years in Indonesia, neither once- nor boost the financial value of logged forests can reduce the economic twice-logged forests recover primary forest levels of above-ground imperative for conversion to alternative land-uses. Potential inter- biomass, yet with enrichment planting and liana cutting, complete ventions depend mainly on forest condition. Where the understorey carbon recovery occurs within 35–40 years (Ruslandi, Cropper, contains existing stocks of commercial seedlings then vines or over- et al., 2017). topping non-commercial trees, which compete for with them light, By reducing collateral tree damage during timber extraction, RIL can be cut or poisoned (Sasaki et al., 2011). This accelerates average can fast-track above-ground biomass recovery (West, Vidal, & Putz, tree growth by 9%–27%, more than doubling the natural growth of 2014), although typically lower harvesting intensities under RIL are commercial species (Peña-Claros et al., 2008). However, excessive rarely controlled for. Indeed, when 50% of biomass is extracted thinning creates light conditions that may favour proliferation of under RIL in the Amazon, natural carbon recovery can still take low-valued pioneer species, such that an optimal thinning intensity up to 75 years (Rutishauser et al., 2015), leading many to promote exists (Swinfield, Afrianda, Antoni, & Harrison, 2016). RIL+, whereby careful extraction is supplemented by post-logging 110 | Journal of Applied Ecology CERULLO and EDWARDS

FIGURE 1 Selected impacts of post-logging interventions on timber, carbon sequestration, non-timber forest products and biodiversity. (a) Recovery of merchantable timber stocks, relative to primary forest levels, in twice-logged forest left naturally regenerating or enriched with line-planted seedlings in Indonesia. Mean observed timber stock values (dots) were used to extrapolate predicted timber stock recovery over time in 20 simulations. (b) Carbon sequestration, measured as annualised net change in above-ground biomass, of subplots in Central Africa subjected to different disturbance intensities. (c) Mean predicted annual fruit production of Brazil nut (Bertholletia excelsa) trees under different liana cutting treatments in Brazil. (d) Total evolutionary history (in millions of years) encompassed by Bornean bird communities in logged forest treated with intensive enrichment planting and liberation cutting, versus unlogged and naturally regenerating forest. Dots depict outliers. Data: A = Ruslandi, Cropper, et al. (2017); B = Gourlet-Fleury, Mortier, et al. (2013); C = Kainer et al. (2014); D = Cosset and Edwards (2017). Shaded envelopes or error bars show 95% confidence intervals. Asterisks show significant differences (p < 0.05) between treatments silvicultural procedures (Peña-Claros et al., 2008; Ruslandi, Cropper, 2010), although the economic viability of active carbon sequestra- et al., 2017; Sasaki et al., 2011). tion within logged forests partly depends on the ability to offset lost Such carbon stock enhancements above the background rates revenues from alternative land-use activities. Payment for seques- of carbon sequestration from natural recovery may become saleable tered carbon from line enrichment planting within logged Bornean as carbon credits under REDD+ initiatives (Edwards, Fisher, & Boyd, forest is significantly less profitable than conversion to oil palm CERULLO and EDWARDS Journal of Applied Ecolog y | 111

(Ruslandi, Romero, et al., 2017), suggesting a need for funding mech- hydrological services (e.g. under REDD+), and via ecotourism or con- anisms that also capture the non-carbon benefits of well-managed servation funds (Walsh, Hidayanto, & Asmui, 2012). Impediments to timber estates. expanding ERC networks include high upfront transaction costs and Ecosystem restoration may also better maintain the important unfavourable taxation structures, although ERCs are galvanising pri- local and regional climate regulating functions provided by logged- vate sector interest (as of 2016, 16 ERC licences have been issued, over forests. Insights from biodiversity ecosystem functioning the- covering 623,075 ha). Empirical examinations of the efficacy of ERCs ory, and experimentation in other biomes, suggest that planting in maintaining forest cover are required to ensure such investments trait-diverse and species-rich seedling mixes could render logged are not just green-washing. forests more resistant and better able to recover from unpredict- Managing NTFPs within degraded forests to bolster against able threats set to intensify under climate change, like parasitism conversion is also complicated by the challenges of tapping into and extreme weather (Mori, Lertzman, & Gustafsson, 2016; O’Brien, diverse commodity markets and scaling up multiple-use forest Reynolds, Ong, & Hector, 2017). The true value of ecosystem res- management. These often make commercial investment into co- toration of logged forest could thus only become apparent retro- management of timber and NTFPs financially unworkable, particu- spectively, when compared to otherwise unrestored logged forests, larly in societies entering capitalist development phases that favour which may be more prone to future breakdowns in carbon storage commodity (e.g. timber) specialisation (García-Fernández, Ruiz- and other ecosystem services. Pérez, & Wunder, 2008). However, because certain NTFPs provide an important means of direct consumption and income generation in local households and markets, hold cultural value, and provide a 3.3 | Non-timber forest products safety net for the forest poor during hardship, enhancing flows of Many people rely on NFTPs for their livelihoods. However, a review locally important NTFPs post-logging might be considered a social found that logging deleteriously impacts NTFP availability in 82% of investment even when wider marketisation is unviable (Shakleton & cases, via direct harvesting or damage of NTFP-providing species, Pandey, 2014). In particular, the emerging forest and landscape res- or by creating a forest environment hostile to NTFP regeneration or toration (FLR) programme under the Bonn Challenge, with its high- availability (Rist et al., 2012). Increasing or recovering NTFP stocks level political buy-in and its broad objectives of enhancing human may thus require active interventions—although some NTFPs re- wellbeing and ecosystem provisioning across landscapes whilst cover unaided after logging (e.g. non-vascular epiphytes) or benefit stocking carbon, might forge partnerships with forestry and non- from enhanced post-logging light conditions (e.g. rattan) (Ashton, forestry governmental departments, enabling better integration of Gunatilleke, Gunatilleke, Tennakoon, & Ashton, 2014). livelihood-enhancing management of NTFPs within logged forests. Where NTFPs are globally or nationally in-demand, post-logging interventions can prove profitable. For instance, Brazil nuts are the 3.4 | Social impacts most valuable NTFP harvested in the Amazon, but logging operations may reduce nut production by damaging trees (Rockwell et al., Forests support livelihoods of over one billion people in extreme 2015). Applying liberation cutting of lianas choking Brazil nut trees poverty, and restoration activities within logged forests can pro- can triple nut production (Figure 1c), boosting harvester’s gross an- vide substantial benefits to rural poor (Edwards et al., 2010). nual incomes by US$500 (Kainer, Wadt, & Staudhammer, 2014). Enhancement of commercially valuable NTFPs can boost household Under certain conditions, NTFP enhancement could protect incomes (Kainer et al., 2014) and provide an important safety net against agricultural conversion by increasing the standing value of during hardship. Post-logging interventions also create jobs for local logged forest and providing a near-term cash flow between tim- people, particularly where policies strive for local workforce recruit- ber harvests. Managing the mixed-dipterocarp forests of Sri Lanka ment (Edwards et al., 2010). Within the tropical logging sector, work- solely for timber fetches approximately a third of the $26,000 ha−1 ers are typically hired on a short-term, discontinuous basis, creating derivable from conversion to tea plantations (Ashton et al., 2001). boom-and-bust employment and unemployment cycles (FAO et al., However, incorporating enrichment planting of commercially valu- 2013). In part, the concentration of labour needs during particular able NTFPs, including sugar-producing fishtail palm, wild cardamom seasons and stages of logging drives this (FAO et al., 2013), suggest- and rattan, alongside timber management, generates $23,000 ha−1 ing that diversifying forest management to include post-logging in- (Net Present Value, under 4% discount rates; Ashton et al., 2001), terventions could increase employment opportunities. incentivising forest retention. Livelihood benefits derived from secure employment, or addi- Enhancing and commercialising NTFPs is an important compo- tional incentive systems, are likely to increase necessary long-term nent of Indonesia’s Ecosystem Restoration Concession (ERC) pro- community support (Holl, 2017). Additionally, interventions could gramme for averting deforestation in unmanaged degraded forests. enhance the provisioning of ecosystem services, including reduced Indonesian businesses apply for management authority over an ERC soil erosion, which affects local fisheries—notwithstanding po- for up to 95 years, committing to zero timber extraction and agri- tentially socially undesirable outcomes (e.g. removal of medicinal cultural conversion. In return, managers can generate income from plants) associated with certain intensive post-logging interventions NTFPs (e.g. fruit, rattan and bamboo), by commercialising carbon or (Guariguata, Garcia-Fernandez, & Sheil, 2010). 112 | Journal of Applied Ecology CERULLO and EDWARDS

(Edwards, Gilroy, et al., 2014). Timber enhancement could influence 3.5 | Biodiversity the long-term viability of land-sparing or land-sharing logging, act- The impacts of post-logging activities on biodiversity hinge on the ing as an important component in designing biodiversity-friendly intervention. Where harvesting has ended, replanting of species concessions. Despite potentially harmful effects at the stand level, targeted by logging—including rare or habitat/food providing spe- intensive timber enhancement could have substantial net biodiver- cies—could reverse biodiversity losses. However, adverse biodiversity benefits if it prevents illegal logging via the continued presence sity impacts may ensue where carbon sequestration or accelerated of forest managers, or more generally, if it discourages the political timber recovery are core aims (Putz & Redford, 2009). First, planting or economic imperative to reclassify logged forest for conversion to of a few fast-growing tree species could reduce tree diversity, pro- low biodiversity plantation (Gaveau et al., 2013), to log spared old- duce an even-aged timber stand vulnerable to ecologically damaging growth patches, or to prematurely re-log forests. timber extraction en masse (Putz & Romero, 2015), and create a for- Edwards, Gilroy, et al. (2014) found that land sparing benefits est lacking resilience to increasingly severe droughts under climate more Bornean bird, leaf-litter ant and dung beetle species than land- change (O’Brien et al., 2017). Second, the removal of vines, climbing sharing logging, whilst also limiting the development of damaging bamboos and understorey plants could negatively affect biodiver- roads (Kleinschroth, Healey, & Gourlet-Fleury, 2016, Figure 2a vs b). sity, because many lianas and understorey species produce fruit, However, the benefits of sparing are presumably undone if future provide dense tangles used as foraging substrate, nesting and pro- logging operations foray into spared forest (Figure 2aii). Since the tection, or are themselves rare (Edwards, Ansell, Ahmad, & Hamer, successful maintenance of uncut forest portions will likely depend 2009). on intensively logged areas maintaining timber yields over time, The limited evidence base suggests mixed impacts of post- timber enhancement within intensively logged areas could protect logging interventions on biodiversity. In Panama, liana removal in- against future incursions into old-growth (Figure 2aiii). creases community-level canopy tree reproduction (León, Izquierdo, Alternatively, Griscom, Goodman, Burivalova, and Putz Mello, Powers, & Schnitzer, 2018) and tree species diversity in log- (2017) demonstrated that when land tenure is secure and Forest ging gaps by 65% (Schnitzer & Carson, 2010), whereas non-timber Stewardship Council-certified RIL is employed, low-intensity land- tree thinning in the Congo Basin has little effect on tree diversity sharing logging might best prevent species loss. A drawback of land- (Gourlet-Fleury, Beina, et al., 2013), though it accelerates post- sharing logging is that stakeholders may intensify logging practices logging recovery of floristic composition (Ouédraogo et al., 2011). following the first low-intensity rotation, thereby subjecting the for- In Borneo, intensive enrichment planting and liberation cutting has est to further degradation and biodiversity loss (Figure 2bii). Timber little or no impact on the abundance of invertebrates (Edwards, enhancement could prevent this by satiating enough of the timber Backhouse, Wheeler, Khen, & Hamer, 2011) or logging sensitive and demand that the remaining forest can continue under low intensity IUCN Red-listed birds (Ansell, Edwards, & Hamer, 2011). treatment (Figure 2biii). There are negative impacts of liberation cutting for fruit-eating birds in Borneo, probably because vines are an important fruit source, but positive impacts for insect-eating birds, which presum- 5 | ALTERNATIVE TARGETS FOR ably benefit from the more open understorey (Edwards et al., 2009). RESTORATIVE INTERVENTIONS Moreover, bird communities inhabiting restored forest in Borneo have fewer species with specialised traits and a more truncated Limited resources for enhancing biodiversity, ecosystem services evolutionary history than communities in naturally regenerating or livelihoods mean that treatments must be cost effective. Key logged forest (Figure 1d), with potential ramifications for ecosystem restoration targets beyond logged forest exist. The FLR agenda service provisioning within these forests (Cosset & Edwards, 2017). seeks to recover landscape-wide ecosystem services and functions This suggests that when the objective is carbon or timber enhance- in degraded areas via recovering secondary forest or establishing ment, interventions should seek to minimise potential threats to agroforestry, silvopasture, or single- or multi-species plantations biodiversity. (Brancalion et al., 2017). Early evidence suggests that market or performance-based climate change mechanisms, like REDD+, are likewise targeting projects in socially and environmentally beneficial 4 | USING TIMBER ENHANCEMENT ways. But how much should post-logging interventions be promoted TO DESIGN BIODIVERSITY-FRIENDLY relative to these alternatives? PRODUCTION LANDSCAPES Natural regrowth of secondary forests on unproductive or aban- doned agricultural lands is a scalable restoration strategy, with yearly A key issue is how to manage logging to least harm biodiversity carbon sequestration 2.3 times that of selectively logged forests in (Edwards, Gilroy, et al., 2014). “Land sparing” logging (Figure 2ai) the Neotropics (Poorter et al., 2016). Moreover, such forests even- couples the protection of large contiguous blocks of old-growth tually recover biodiverse communities (Gilroy et al., 2014), although forest with intensive logging elsewhere, whereas “land sharing” land-zoning mechanisms are required to ensure that any regrowth is logging (Figure 2bi) applies less-intensive logging over larger scales not undermined by future conversion (Phalan et al., 2016). However, CERULLO and EDWARDS Journal of Applied Ecolog y | 113

(a) LAND SPARING (b) LAND SHARING (i) (i)

Old-growth forest

High-intensity logging

Low-intensity logging

R Restored forest

Road

(ii) (iii) (ii) (iii)

RRR RRR RRRR R RRR RRRRR R RRRR

FIGURE 2 Possible impacts of timber enhancement under “land-sparing” (a) or “land-sharing” (b) logging approaches. Each figure shows a hypothetical logging concession. During land-sparing logging (a), intensive timber extraction in one area enables the retention of a primary forest block (i). Further demand for timber may result in the spared primary forest block being logged (ii), but enhancement of timber values in intensively logged forest could meet this demand and prevent incursions into primary forest (iii). During land-sharing logging (b), low- intensity timber extraction is applied across the entire concession (i). Further demand for timber may drive more intensive re-logging and/or an early return for a further low intensity harvest (ii). However, timber enhancement could mean that demand can be met via early re-logging whilst maintaining low intensity harvesting (iii)

a recent meta-analysis found highly variable forest recovery for both benefits arising if logged forest interventions simultaneously avert actively and passively restored former agricultural lands (Meli et al., agricultural conversion. 2017) and large-scale regrowth on viable cropland could trigger Planning might also include the various opportunity costs under conversion of intact forest. Thus, although greater ecological gains different logged forest management regimes. For instance, carbon- might occur when restoration is targeted towards re-growing forest, or other ecosystem service-enhancements within once-logged for- this may switchback towards post-logging interventions whenever est where future logging is prevented will have large opportunity this averts deforestation, because of the disproportionate erosion of costs from forgone timber revenues, and as such these activities are biodiversity that follows conversion of intact and relatively unfrag- likely more cost-effective and permanent when targeted towards mented forest (Betts et al., 2017). timber depleted forests (e.g. Fisher et al., 2011). Alternatively, where Forest and landscape restoration activities and funds could en- silviculture is conducted between logging rotations to maintain tim- ergise ecosystem restoration, or carbon and ecosystem service en- ber yields within permanent timber estate, opportunity costs will hancement (see Table 1) within ex-production forest, especially near likely be lower. well-populated areas. Urgent exploration of the comparative social, environmental and economic costs and benefits of different interventions within heterogeneous landscapes are needed. For example, 6 | OPERATIONALISING POST-LOGGING Budiharta et al. (2014) integrate data on the habitat sensitivity of INTERVENTIONS threatened mammal species, with model-derived estimates of the future carbon sequestration potential and specific cost of various Timber logging in the tropics is geared towards short-term profit restoration techniques, to systematically prioritise activities within maximisation over long-term sustainability, rarely spawning man- forests of varying condition in East Kalimantan. Ultimately, such agement plans beyond initial timber harvesting. High discount rates strategic planning should factor-in opportunities for natural or as- and upfront costs of seedling planting or liberation cutting generally sisted regeneration on deforested lands, as well as the substantial make timber enhancement for future harvests commercially risky and 114 | Journal of Applied Ecology CERULLO and EDWARDS uneconomic (Schulze, 2008; Schwartz, Bais-Moleman, Peña-Claros, alternative restoration investments. Governments can forge eco- & Arts, 2016), although certain interventions are profitable for long- nomic environments favourable to corporate investment by reducing term investors (Ruslandi, Romero, et al., 2017). For ecosystem resto- the costs (or increasing profits) of interventions, via subsidies, loans, ration or ecosystem service enhancement, the resources, expertise direct payment or tax breaks (Brancalion et al., 2017). For instance, and governance needed are typically lacking, whilst the permanence governments should redirect reforestation funds paid by concession- of interventions is questionable, because logged forests are usually aires back into timber enhancing activities in their own concessions degradation and deforestation prone areas. Together, these factors or provide discount rates for carbon enhancement in line with those explain why post-logging interventions largely remain confined to for climate-change projects (Ruslandi, Cropper, et al., 2017). experimental plots and small-scale projects subsidised by conserva- Payment for ecosystem services schemes, including REDD+, tion charities and external agencies (Putz & Romero, 2015). could levy funds for interventions that increase carbon storage above Depleting stocks coupled with increasing demand for tropical business-as-usual rates (Edwards, Tobias, et al., 2014; Ruslandi, timber may cement timber enhancement as a new trajectory in pro- Romero, et al., 2017). Thus far, the materialisation of carbon mar- duction forests (Putz & Romero, 2015). Spurring transitions towards kets has been underwhelming, with funds from both voluntary and well-managed timber landscapes that sustain yields of commercially regulated markets (only US$220 million in 2012) dwarfed by gov- important species in socially and environmentally acceptable ways ernment support for REDD+ (over US$7 billion in 2014) (Brancalion requires institutions that generate the funding and enabling policies et al., 2017), and rarely invested in better management of produc- needed for post-logging interventions, influence business norms, tion forests (Putz & Romero, 2015). However, with the likely growth build capacity and optimise existing practices. of nonmarket-funded REDD+ financed by performance-based payments from the Green Climate Fund (Angelsen et al., 2017), new opportunities for logging companies employing climate-smart prac- 6.1 | Influencing business norms tices may emerge. Much tropical logging is conducted by large (trans-) national corpo- Because even intensively treated logged forests presumably rations, known to “cut-and-run” (Laurance, 2000). However, such maintain key soil and watershed processes, as well as biodiversity corporations could also drive transformative change in production (Ansell et al., 2011), a fruitful avenue for funding post-logging inter- forestry because they control significant areas, are connected across ventions is complementing carbon payments with other payments for the tropics by a network of subsidiaries, engage directly in high-level ecosystem services (Brancalion et al., 2017) and targeting such bun- governance processes and some are vertically integrated (operat- dles towards well-managed timber estates. Moreover, since the FLR ing throughout supply chains from logging to retail) (Österblom, agenda includes climate change mitigation and improved human well- Jouffray, Folke, & Rockström, 2017). Scientists and donors have being, some forthcoming funds might be directed towards increasing understandably hesitated to engage such corporations, because of carbon sequestration and hardwood recovery between rotations in their reputation for forest degradation (Griscom et al., 2017). active logging concessions, whenever this demonstrably provides cli- Whilst we condemn malpractice, industrial logging will continue matic benefits and silvicultural employment for local people. within tropical forests and short-term attempts to reduce logging levels within legal concessions might be counteracted by upsurges 6.3 | Enabling policies in illegal logging or climate change-driving substitution of wood with high-energy building materials. Ensuring logging in legal concessions Commercial reluctance to invest in post-logging interventions often is sustainable thus requires important actors to adopt “cut-and- arises because political volatility and granting of short-term timber stay” mentalities, beyond simply reducing the impacts of harvesting. exploitation licences means concessionaries risk not cashing-in on Institutions must find leverage points for catalysing such system- future benefits accrued by present day management (FAO and van wide shifts in business norms. Forging new science-business initia- Hensbergen, 2016). By issuing long-lasting licences and awarding tives that engage keystone actors in solution-focused sustainability new concessions based on a track record of high-quality manage- initiatives (e.g. Österblom et al., 2017) is a largely unexplored avenue ment, governments could promote commercial investment in long- that holds potential in driving transformative change. Encouraging term yield-sustaining activities (FAO and van Hensbergen, 2016). certification standards to steer more aggressively towards sustain- If well managed, such concessions would further supplement con- ing timber yields could forge further improvements (Peña-Claros servation efforts outside of protected areas (Gaveau et al., 2013). et al., 2008), notwithstanding the presumably lower uptake of stron- Additionally, governments should introduce legal and enforce- ger labels, costly certification, and at-times relatively poor enhanced ment mechanisms similar to the mining sector, which dictate post- market access relative to uncertified timber. exploitation interventions. Since logged forests have important restoration potential within heterogeneous, degraded landscapes, policies should strive 6.2 | Securing funding to extend the socio-economic role of post-logging interventions Stimulating greater commercial investment could make post-logging within wider landscapes, via mechanisms such as community for- interventions self-financing, releasing them from competition with est management (Asare, Keyei, & Mason, 2013) and public-private CERULLO and EDWARDS Journal of Applied Ecolog y | 115 partnerships. A critical barrier is clarifying and securing land tenure 2017), particularly when coupled with top-down land-zoning that and improving sectorial land planning, since forest management li- renders treated forests off-limits from conversion. Piloting innova- cences are usually expensive, large in area, and relatively short term. tive post-logging interventions at various scales and under different Breaking down such barriers to award smaller licences that enable incentive/disincentive structures could reveal low-cost options for integrated community management of heterogeneous landscapes large-scale roll-out and iterative adjustment according to local polit- (e.g. Asare et al., 2013) is critical if post-logging interventions are to ical or socioecological dynamics. take a central role in the FLR agenda.

7 | OUTSTANDING QUESTIONS AND 6.4 | Optimising post-logging interventions FUTURE DIRECTIONS

Expensive restocking through enrichment planting should be con- 7.1 | The economics and feasibility of post-logging fined to forests with low natural regeneration of timber species, with interventions liberation of existing seedlings employed within well-stocked forest (Ruslandi, Cropper, et al., 2017). Where enrichment planting is re- The long-term profitability of liberation cutting, thinning of mer- quired, key is ensuring seed or seedling stocks have ample genetic chantable species (particularly with mechanisation) and enrichment diversity (Kettle, 2010; Thomas et al., 2014), by knowledge-sharing planting are unknown for most of the tropics. Although line-planting of seed selection and supply options, and exchanging seeds across with dipterocarps at large scales in Borneo generates substantial tim- landscapes (Jalonen, Valette, Boshier, Duminil, & Thomas, 2017). ber volume increments (Dawkins & Philips, 1998; Ruslandi, Cropper, Furthermore, enrichment planting should be designed to minimise et al., 2017), the technical and financial feasibility of planting regimes ecological impacts, including of future timber extraction (Putz & elsewhere are less well established and hard to extrapolate to indus- Romero, 2015). Inter-planting timber species that mature at differ- trial scales. Most studies calculate future yields based on short-term ent speeds, rather than enriching stands with species that reach har- measurements of seedling survival and growth rates within a few vestable sizes near-simultaneously, could protect against impacts small experimental plots (e.g. Schulze, 2008), thus generating high tantamount to clear-cutting logging. Concentrating intensive treat- uncertainty and leaving significant scope for longer-term and larger- ments to small areas (“land-sparing” timber enhancement) could spa- scale assessments. tially constrain any deleterious biodiversity impacts. Other crucial questions include: (a) what is the cost-effectiveness Innovative silvicultural practices worthy of immediate explo- of sequestered carbon in production forest; (b) what combinations ration exist. One promising example is exploiting the suitability of of penalties, rewards and forest concession licensing or tenure ar- logging road verges to support valuable fast-growing timber species rangements can incentivise adoption of appropriate silvicultural in the Amazon and Congo Basin. Roadside seedling enrichment or practices by logging industries or communities; and (c) which busi- liberation could be financially remunerative, buffer forest interiors ness models and scenarios make managing logged forests for res- from edge effects, and spare forest from new road construction toration viable and scalable over land-use alternatives? Developing during subsequent rotations by promoting reopening of old roads to and evaluating post-logging interventions that recover the economic harvest roadside timber (Kleinschroth et al., 2016). potential of exhausted timber concessions and thus constrain their risk of conversion is crucial (Harrison & Swinfield, 2015).

6.5 | Building capacity and scalability 7.2 | Impact on ecosystem services and NTFPs Optimally implementing post-logging interventions largely depends on: (a) availability of foresters trained in silviculture (Putz & Romero, Long-term effects of forest interventions on soil fertility, water re- 2015); (b) often-lacking taxonomic expertise to identify naturally tention, carbon storage and resilience against stressors including regenerating merchantable seedlings for liberation and monitor drought and parasitism are unknown. Optimal management even for the impacts of post-logging silviculture on wider biodiversity; and internationally traded NTFPs is little understood, leaving scope for (c) finding ways of making interventions technically and financially empirical exploration of NTFP-maximising strategies in production scalable. Whilst these constraints are symptomatic of the presently forest. In some cases, planting lianas may aid restoration by sealing low commercial and political emphasis on post-logging management, forest edges from edge effects and supporting important ecological they are not insurmountable. and geochemical processes (e.g. nutrient turnover), but this requires Training programmes like those used for RIL could enhance sil- validation (Campbell, Edwards, Odell, Mohandass, & Laurance, 2015). vicultural capacity (Sasaki et al., 2011) and para-botanical expertise, easy to identify and monitor indicator taxa could facilitate moni- 7.3 | Impact on biodiversity toring of wider biodiversity, whilst company-community models, including timber out-grower training schemes, can engage local The impact of post-logging interventions on most taxonomic groups communities. Investing in social capital via bottom-up approaches and potential benefits of wildlife-friendly practices, including sup- would help ensure the permanence of restoration efforts (Holl, plementing enrichment planting of commercial species with fruit 116 | Journal of Applied Ecology CERULLO and EDWARDS trees and applying breaks or reduced-intensity in liberation cutting ACKNOWLEDGEMENTS to allow retention of microhabitats (Ansell et al., 2011) are untested. We thank Rhett Harrison and an anonymous reviewer for comments Long-term experiments that measure carbon, timber and biodiver- that greatly improved the manuscript. sity outcomes along manipulated gradients of post-logging silvicultural intensities would be invaluable for assessing synergies and trade-offs. Such joint assessments of timber production, economic AUTHORS’ CONTRIBUTIONS productivity and biodiversity outcomes of various interventions Both authors contributed equally to writing this manuscript. could also inform best practices for designing biodiversity-friendly concessions (Figure 2). Ultimately, this could instruct least-harmful application of ecologically damaging activities—for example, by DATA ACCESSIBILITY demonstrating whether for a given volume of recovered timber, it is Data have not been archived because this article does not use data. better for biodiversity to concentrate intensive liberation cutting in a small forest area or employ lower-intensity liberation cutting (e.g., incorporating cutting breaks) at wider scales. ORCID

Gianluca R. Cerullo http://orcid.org/0000-0002-4903-6202 7.4 | When to restore a logged forest

Vital management decisions include when to actively intervene and REFERENCES when to allow unassisted recovery of logged forests. This depends on Angelsen, A., Brockhaus, M., Duchelle, A. E., Larson, A., Martius, C., the degradation level (Rutishauser et al., 2015) and cost-benefit ratio Sunderlin, W. D., … Wunder, S. (2017). Learning from REDD+: A re- of interventions relative to other land-use targets, including restora- sponse to Fletcher et al. Conservation Biology, 31, 718–720. https:// tion alternatives (Budiharta et al., 2014). Whether enhancement of doi.org/10.1111/cobi.12933 future timber stocks favours early re-logging or increases a forest’s Ansell, F. A., Edwards, D. P., & Hamer, K. C. (2011). Rehabilitation of logged rain forests: avifaunal composition, habitat structure, and im- standing value, reducing conversion risk (Edwards, Tobias, et al., 2014), plications for biodiversity-friendly REDD+. Biotropica, 43, 504–511. and whether passive regeneration and the associated lack of forest op- https://doi.org/10.1111/j.1744-7429.2010.00725.x erators increases the risk of illegal encroachment or reclassification to Aronson, J., & Alexander, S. (2013). Ecosystem restoration is now a global industrial plantations (Gaveau et al., 2013; Zahawi, Reid, & Holl, 2014) priority: time to roll up our sleeves. Restoration Ecology, 21, 293–296. https://doi.org/10.1111/rec.12011 are research frontiers. Given various post-logging objectives (Table 1), Asare, R. A., Keyei, A., & Mason, J. J. (2013). A community resource developing multi-stakeholder platforms would help determine the management area mechanism: a strategy to manage African forest type and spatial configuration of interventions to deliver mutual con- resources for REDD+. Philosophical Transactions of the Royal Society servation, timber or social benefits (Ruslandi, Cropper, et al., 2017). B Biological Sciences, 368, e20120311. https://doi.org/10.1098/ rstb.2012.0311 Ashton, M. S., Gunatilleke, I. N., Gunatilleke, C. S., Tennakoon, K., & Ashton, P. S. (2014). Use and cultivation of plants that yield products 8 | CONCLUSIONS other than timber from South Asian tropical forests and their potential in forest restoration. Forest Ecology & Management, 329, 360–374. Retaining unlogged, old-growth forest within networks of protected https://doi.org/10.1016/j.foreco.2014.02.030 Ashton, M. S., Mendelsohn, R., Singhakumara, B. M., Gunatilleke, C. V., areas remains a global priority (Gibson, Lee, Koh, & Sodhi, 2011; Gunatilleke, I. A., & Evans, A. (2001). A financial analysis of rain- Lewis et al., 2015). However, this alone cannot retain tropical spe- forest silviculture in southwestern Sri Lanka. Forest Ecology and cies into the future, reinforcing the importance of human-impacted Management, 5526, 1–11. forests in on-going conservation agendas. Logged tropical forests Asner, G. P., Rudel, T. K., Aide, T. M., Defries, R., & Emerson, R. (2009). A contemporary assessment of change in humid trop- are second only to old-growth forest in their biological value and ca- ical forests. Conservation Biology, 23, 1386–1395. https://doi. pacity to provision an array of ecosystem services valued by human- org/10.1111/j.1523-1739.2009.01333.x kind. However, they are vulnerable to a suite of threats, including Betts, M. G., Wolf, C., Ripple, W. J., Phalan, B., Millers, K. A., Duarte, agricultural conversion (Edwards, Tobias, et al., 2014). In this review, A., … Levi, T. (2017). Global forest loss disproportionately erodes biodiversity in intact landscape. Nature, 547, 441–444. https://doi. we provide evidence that the growing dominance of production org/10.1038/nature23285 forest landscapes and the failures of past efforts to reduce logging Blaser, J., Sarre, A., Poore, D., & Johnson, S. (2011). Status of tropical for- means that alongside working to improve existing logging practices, est management 2011, ITTO technical series No. 38. Yokohama, Japan: post-logging interventions are important for improving logged forest International Tropical Timber Organization. Bonn Challenge. (2018). http://www.bonnchallenge.org/ management and breathing new life into already degraded forests. Brancalion, P. H. S., Lamb, D., Ceccon, E., Boucher, D., Herbohn, J., The research gaps and opportunities for optimising these interven- Strassburg, B., & Edwards, D. P. (2017). Using markets to lever- tions that we have identified require further study to ensure that age investment in forest and landscape restoration in the tropics. logged forests unlock their full potential in emerging global restora- Forest Policy and Economics, 85, 103–113. https://doi.org/10.1016/j. forpol.2017.08.009 tion agendas. CERULLO and EDWARDS Journal of Applied Ecolog y | 117

Budiharta, S., Meijjaard, E., Erksine, P. D., Rondinini, C., Pacifici, M., & tropical biodiversity. Nature, 478, 378–381. https://doi.org/10.1038/ Wilson, K. A. (2014). Restoring degraded tropical forests for carbon nature10425 and biodiversity. Environmental Research Letters, 9, 114020. https:// Gilroy, J. J., Woodcock, P., Edwards, F. A., Wheeler, C., Baptiste, B. L. G., doi.org/10.1088/1748-9326/9/11/114020 Medina Uribe, C. A., … Edwards, D. P. (2014). Cheap carbon and bio- Campbell, M. J., Edwards, W., Odell, E., Mohandass, D., & diversity cobenefits from forest regeneration in a hotspot of ende- Laurance, W. F. (2015). Can lianas assist in rainforest resto- mism. Nature Climate Change, 6, 503–507 https://doi.org/10.1038/ ration? Tropical Conservation Science, 8, 257–273. https://doi. nclimate2200 org/10.1177/194008291500800119 Gourlet-Fleury, S., Beina, D., Fayolle, A., Ouèdraogo, D.-Y., Mortier, F., Cosset, C. C. P., & Edwards, D. P. (2017). The effects of restoring logged Bènèdet, F., … Decocq, G. (2013). Silvicultural disturbance has lit- tropical forests on avian phylogenetic and functional diversity. tle impact on tree species diversity in a Central African Moist Ecological Applications, 6, 1932–1945. https://doi.org/10.1002/ Forest. Forest Ecology and Management, 304, 322–332. https://doi. eap.1578 org/10.1016/j.foreco.2013.05.021 Dawkins, H. C., & Philips, M. S. (1998). Tropical moist forest silviculture Gourlet-Fleury, S., Mortier, F., Fayolle, A., Baya, F., Ouédraogo, D., and management: A history of success and failure. Wallingford, UK: Bénédet, F., & Picard, N. (2013). Tropical forest recovery from CAB International. logging: a 24-year silvicultural experiment from Central Africa. Durán, S. M., & Ernasto, G. (2013). Carbon stocks in tropical forests de- Philosophical Transactions of the Royal Society B Biological Sciences, crease with liana density. Biology Letters, 12, e20130301. https://doi. 368, e20120302. https://doi.org/10.1098/rstb.2012.0302 org/10.1098/rsbl.2013.0301 Griscom, B. W., Goodman, C. R., Burivalova, Z., & Putz, F. E. (2017). Edwards, D. P., Ansell, F. A., Ahmad, A. H., & Hamer, K. C. (2009). The value Carbon and biodiversity impacts of intensive versus extensive tropi- of rehabilitating logged rainforest for birds. Conservation Biology, 23, cal forestry. Conservation Letters, 11, e12362. 1628–1633. https://doi.org/10.1111/j.1523-1739.2009.01330.x Guariguata, M. R., Garcia-Fernandez, C., & Sheil, D. (2010). Compatibility Edwards, D. P., Backhouse, A. R., Wheeler, C., Khen, C. V., & Hamer, K. of timber and non-timber forest product management in natural C. (2011). Impacts of logging and rehabilitation on invertebrate com- tropical forests: perspectives, challenges, and opportunities. Forest munities in tropical rainforests of northern Borneo. Journal of Insect Ecology and Management, 259, 237–245. https://doi.org/10.1016/j. Conservation, 16, 591–599. foreco.2009.11.013 Edwards, D. P., Fisher, B., & Boyd, E. (2010). Protecting de- Harrison, R., & Swinfield, T. (2015). Restoration of logged humid trop- graded rainforests: Enhancement of forest carbon stocks ical forests: An experimental programme at Harapan Ranforest, under REDD+. Conservation Letters, 3, 313–316. https://doi. Indonesia. Tropical Conservation Science, 8, 4–16. https://doi. org/10.1111/j.1755-263X.2010.00143.x org/10.1177/194008291500800103 Edwards, D. P., Gilroy, J. J., Woodcock, P., Edwards, F. A., Larsen, T. Holl, K. D. (2017). Restoring tropical forests from the bottom up. Science, H., Andrews, D. J. R., … Wilcove, D. S. (2014). Land-sharing versus 355, 455–456. https://doi.org/10.1126/science.aam5432 land-sparing logging: Reconciling timber extraction with biodiver- Jalonen, R., Valette, M., Boshier, D., Duminil, J., & Thomas, E. (2017). sity conservation. Global Change Biology, 20, 183–191. https://doi. Forest and landscape restoration severely constrained by a lack of org/10.1111/gcb.12353 attention to the quantity and quality of tree seeds: Insights from a Edwards, D. P., Tobias, J. A., Sheil, D., Meijaard, E., & Laurance, W. F. global survey. Conservation Letters, 11, e12424. (2014). Maintaining ecosystem function and services in logged trop- Kainer, K. A., Wadt, L. H., & Staudhammer, C. L. (2014). Testing a sil- ical forests. Trends in Ecology and Evolution, 29, 511–520. https://doi. vicultural recommendation: Brazil nut responses 10 years after org/10.1016/j.tree.2014.07.003 liana cutting. Journal of Applied Ecology, 51, 655–663. https://doi. FAO. Estruch, E., & Rapone, C. (2013). Promoting decent employment in org/10.1111/1365-2664.12231 forestry for improved nutrition and food security. Background paper Kettle, C. J. (2010). Ecological considerations for using diptero- for the International Conference on Forests for Food Security and carps for restoration of lowland rainforest in Southeast Asia. Nutrition, 1–14. Rome. Biodiversity Conservation, 19, 1137–1151. https://doi.org/10.1007/ FAO. van Hensbergen, B. (2016). Forest concessions—Past, present and s10531-009-9772-6 future? Forestry Policy and Institutions Working Paper 36, 1–59. Kleinschroth, F., Healey, J. R., & Gourlet-Fleury, S. (2016). Sparing for- Rome. ests in Central Africa: Re-use old logging roads to avoid creating new Fisher, B., Edwards, D. P., Larsen, T. H., Ansell, F. A., Hsu, W. W., ones. Frontiers in Ecology and the Environment, 14, 9–10. https://doi. Roberts, C. S., & Wilcove, D. S. (2011). Cost-effective con- org/10.1002/FEEKleinscrothletter.1 servation: calculating biodiversity and logging trade-offs in Laurance, W. F. (2000). Cut and run: The dramatic rise of transnational Southeast Asia. Conservation Letters, 4, 443–450. https://doi. logging in the tropics. Trends in Ecology & Evolution, 15, 433–434. org/10.1111/j.1755-263X.2011.00198.x https://doi.org/10.1016/S0169-5347(00)01962-5 García-Fernández, C., Ruiz-Pérez, M., & Wunder, S. (2008). Is multiple- León, M. M. G., Izquierdo, L. M., Mello, F. N. P., Powers, J. S., & Schnitzer, use forest management widely implementable in the tropics? Forest S. A. (2018). Lianas reduce community-level canopy tree reproduc- Ecology and Management, 256, 1468–1476. https://doi.org/10.1016/j. tion in a Panamanian forest. Journal of Ecology, 107, 737–745. foreco.2008.04.029 Lewis, S. L., Edwards, D. P., & Galbraith, D. (2015). Increasing human Gaveau, D. A., Kshatriya, M., Sheil, D., Sloan, S., Molidena, E., Wijaya, A., dominance of tropical forests. Science, 349, 827–832. https://doi. … Meijaard, E. (2013). Reconciling forest conservation and logging in org/10.1126/science.aaa9932 Indonesian Borneo. PLoS ONE, 8, e69887. https://doi.org/10.1371/ Meli, P., Holl, K. D., Rey Benayas, J. M., Jones, H. P., Jones, P. C., Montoya, journal.pone.0069887 D., … Mateos, D. M. (2017). A global review of past land use, climate, Gaveau, D. A., Sheil, D., Husnayaen, P., Salim, M. A., Arjasakusuma, S., and active vs. passive restoration effects on forest recovery. PLoS Ancrenaz, M, … Meijaard, E. (2016). Rapid conversions and avoided ONE, 12, e0171368. https://doi.org/10.1371/journal.pone.0171368 deforestation: examining four decades of industrial plantation expan- Mori, S. M., Lertzman, K. P., & Gustafsson, L. (2016). Biodiversity and sion in Borneo. Scientific Reports, 6, e32017. https://doi.org/10.1038/ ecosystem services in forest ecosystems: A research agenda for ap- srep32017 plied forest ecology. Journal of Applied Ecology, 54, 12–27. Gibson, L., Lee, T. M., Koh, L. P., Brook, B. W., Gardner, T. A., Barlow, J., O’Brien, M. J., Reynolds, G., Ong, R., & Hector, A. (2017). Resistance … Sodhi, N. S. (2011). Primary forests are irreplaceable for sustaining of tropical seedlings to drought is mediated by neighbourhood 118 | Journal of Applied Ecology CERULLO and EDWARDS

diversity. Nature Ecology and Evolution, 1, 1643–1648. https://doi. managed Amazonian forests. Current Biology, 25, 787–788. https:// org/10.1038/s41559-017-0326-0 doi.org/10.1016/j.cub.2015.07.034 Oliver, C. D., Nassar, T. N., Lippke, B. R., & McCarter, J. B. (2013). Carbon, Sasaki, N., Asner, G. P., Knorr, W., Durst, P. B., Priyadi, H. R., & Putz, F. fossil fuel, and biodiversity mitigation with wood and forests. Journal E. (2011). Approaches to classifying and restoring degraded tropical of Sustainable Forestry, 33, 248–275. forests for the anticipated REDD+ climate change mitigation mecha- Österblom, H., Jouffray, J. B., Folke, C., & Rockström, J. (2017). nism. iForest, 4, 1–6. https://doi.org/10.3832/ifor0556-004 Emergence of a global science-business initiative for ocean steward- Schnitzer, S. A., & Carson, W. P. (2010). Lianas suppress tree regeneration ship. Proceedings of the National Academy of Sciences of the USA, 114, and diversity in treefall gaps. Ecology Letters, 12, 849–858. https:// 9038–9043. https://doi.org/10.1073/pnas.1704453114 doi.org/10.1111/j.1461-0248.2010.01480.x Ouédraogo, D. Y., Beina, D., Picard, N., Mortier, F., Baya, F., & Gourlet- Schulze, M. (2008). Technical and financial analysis of enrichment plant- Fleury, S. (2011). Thinning after selective logging facilitates floristic ing in logging gaps as a potential component of forest management in composition recovery in a tropical rain forest of Central Africa. Forest the eastern Amazon. Forest Ecology and Management, 255, 866–879. Ecology and Management, 262, 2176–2186. https://doi.org/10.1016/j. https://doi.org/10.1016/j.foreco.2007.09.082 foreco.2011.08.009 Schwartz, G., Bais-Moleman, A. L., Peña-Claros, M., & Arts, B. J. M. Pearson, T. H., Brown, S., Murray, L., & Sidman, G. (2017). Greenhouse (2016). Profitability of silvicultural treatments in logging gaps in the gas emissions from tropical forest degradation: An underesti- Brazilian Amazon. Journal of Tropical Forest Science, 28, 68–78. mated source. Carbon Balance and Management, 12, 3. https://doi. Schwartz, G., Pereira, P. C., Siviero, M. A., & Yared, J. A. (2017). Enrichment org/10.1186/s13021-017-0072-2 planting in logging gaps with Schizolobium parahyba var. amazonicum: Peña-Claros, M., Fredericksen, T. S., Alarcón, A., Blate, G. M., Choque, A financially profitable alternative for degraded tropical forests in U., Leano, C., … Putz, F. E. (2008). Beyond reduced-impact log- the Amazon. Forest Ecology and Management, 390, 166–172. https:// ging: Silvicultural treatments to increase growth rates of tropical doi.org/10.1016/j.foreco.2017.01.031 trees. Forest Ecology and Management, 256, 1458–1467. https://doi. Shakleton, C. M., & Pandey, A. K. (2014). Positioning non-timber forest org/10.1016/j.foreco.2007.11.013 products on the development agenda. Forest Policy and Economics, Phalan, B., Green, R. E., Dicks, L. V., Dotta, G., Feniuk, C., Lamb, A., … 38, 1–7. https://doi.org/10.1016/j.forpol.2013.07.004 Balmford, A. (2016). How can higher-yield farming help to spare na- Sist, P., Picard, N., & Gourlet-Fleury, S. (2003). Sustainable cutting cycles ture? Science, 351, 450–451. https://doi.org/10.1126/science.aad0055 and yields in lowland mixed dipterocarp. Annals of Forest Science, 60, Poorter, L., Bongers, F., Aide, T. M., Aide, T. M., Almeyda Zambrano, A. 803–814. https://doi.org/10.1051/forest:2003075 M., Balvanera, P., Becknell, J. M., … Rozendaal, D. A. (2016). Biomass Sloan, S., Edwards, D. P., & Laurance, W. F. (2012). Does Indonesia’s resilience of neotropical secondary forests. Nature, 530, 211–214. REDD+ moratorium on new concessions spare imminently threat- https://doi.org/10.1038/nature16512 ened forests? Conservation Letters, 5, 222–231. https://doi. Putz, F. E., & Redford, K. H. (2009). Dangers of carbon-based conser- org/10.1111/j.1755-263X.2012.00233.x vation. Global Environmental Change, 19, 400–401. https://doi. Swinfield, T., Afrianda, R., Antoni, F., & Harrison, R. D. (2016). Accelerating org/10.1016/j.gloenvcha.2009.07.005 tropical forest restoration through the selective removal of pioneer Putz, F. E., & Romero, C. (2015). Futures of tropical production forests species. Forest Ecology and Management, 38, 209–216. https://doi. (CIFOR Occasional Paper no. 134). Center for International Forestry org/10.1016/j.foreco.2016.09.020 Research. Thomas, E., Jalonen, R., Loo, J., Boshier, D., Gallo, J., Cavers, S., … P u t z , F. E., Zuid e m a , P. A., Sy n n ot t , T., Pe ña‐ C la ros , M., Pina rd , M. A., S h eil , D., Bozanno, M. (2014). Genetic considerations in ecosystem resto- … Zagt, R. (2012). Sustaining conservation values in selectively logged ration using native tree species. Forest Ecology and Management, 333, tropical forests: The attained and the attainable. Conservation Letters, 66–75. https://doi.org/10.1016/j.foreco.2014.07.015 5, 296–303. https://doi.org/10.1111/j.1755-263X.2012.00242.x Villegas, Z., Peña-Claros, M., Mostacedo, B., Alarcón, A., Licona, J. C., Leaño, Rist, L., Shanley, P., Sunderland, T., Sheil, D., Ndoye, O., Liswanti, C., … Choque, U. (20 09). Silvicultural treatment s enhance grow th rates of N., & Tieguhong, J. (2012). The impacts of selective logging future crop trees in a tropical dry forest. Forest Ecology and Management, on nontimber forest products of livelihood importance. Forest 258, 971–977. https://doi.org/10.1016/j.foreco.2008.10.031 Ecology and Management, 268, 57–69. https://doi.org/10.1016/j. Walsh, T. A., Hidayanto, Y., & Asmui, A. B. (2012). Ecosystem restoration foreco.2011.04.037 in Indonesia’s production forests: Towards financial feasibility. Good Rockwell, C. A., Guariguata, M. R., Menton., M., Arroyo Quispe, E., Business: making private investments work for tropical forests. ETFRN Quaedvlieg, J., Warren-Thomas, E., … Salas, A. J. Y. (2015). Nut NEWS 54. European Tropical Forest Research Network, 35–41. production in Bertholletia excelsa across a logged forest mosaic: West, T. A., Vidal, E., & Putz, F. E. (2014). Forest biomass recovery after conven- Implications for multiple forest use. PLoS ONE, 10, e0135464. tional and reduced impact logging in Amazonian Brazil. Forest Ecology and https://doi.org/10.1371/journal.pone.0135464 Management, 314, 59–63. https://doi.org/10.1016/j.foreco.2013.11.022 Ruslandi, Cropper, W. P., & Putz, F. E. (2017). Effects of silvicultural inten- Zahawi, R. A., Reid, J. L., & Holl, K. D. (2014). Hidden costs of passive res- sification on timber yields, carbon dynamics, and tree species compo- toration. Restoration Ecology, 22, 284–287. https://doi.org/10.1111/ sition in a dipterocarp forest in Kalimantan, Indonesia: An individual- rec.12098 tree-based model simulation. Forest Ecology and Management, 390, 104–118. https://doi.org/10.1016/j.foreco.2017.01.019 Ruslandi, Romero, C., & Putz, F. E. (2017). Financial viability and car- How to cite this article: Cerullo GR, Edwards DP, Actively bon payment potential of large-scale silvicultural intensification in restoring resilience in selectively logged tropical forests. J Appl logged dipterocarp forests in Indonesia. Forest Policy and Economics, Ecol. 2019;56:107–118. https://doi.org/10.1111/1365- 85, 95–102. https://doi.org/10.1016/j.forpol.2017.09.005 Rutishauser, E., Hérault, B., Baraloto, C., Blanc, L., Descroix, L., Doff 2664.13262 Sota, E., … Sist, P. (2015). Rapid tree carbon stock recovery in