Introduction

Drawing on a case study from Papua New Guinea (PNG), this paper investigates how managed shade trees can improve labour efficiencies in smallholder coffee production and contribute to the development of more sustainable and resilient livelihood systems. Shade trees have long been used in commercial coffee production to simulate the forest environment in which coffee trees evolved (Alemu 2015). However, in recent decades to raise yields, there has been a trend to unshaded coffee grown in monocultures under intense husbandry using high levels of inputs. While this practice has produced much higher yields in capital-intensive plantation settings, it has often been environmentally unsustainable for smallholders not maintaining the high input levels necessary for healthy and productive coffee trees (Beer et al. 1997; Muschler 2009).

Over 70% of the world’s coffee is produced on small-scale farms in the tropics relying mainly on family labour using simple production and processing technologies (Oxfam 2001 cited in Bacon 2005: 497). As worldwide demand for coffee has increased together with rising demand for speciality and certified coffee, there has been an impetus to develop more sustainable smallholder coffee production systems (Prabhakaran Nair 2010). A growing interest in the social, economic and environmental benefits of agroforestry and regenerative farming is stimulating more research in the use of shade trees in coffee and cocoa production. Much of the research has focused on the role of shade trees in providing ecosystem services that improve agronomic and ecological aspects of multi-crop land-use systems (e.g. Boreux et al. 2013; Jaramillo et al. 2013; Jha et al. 2014; Charbonnier et al. 2017; Hosseini Bai et al. 2017) and the potential of agroforestry production systems in coffee and cocoa for increasing returns to farmers and ameliorating the effects of climate change (e.g. Rosenberg and Marcotte 2005; Lasco et al. 2014; Gao 2018; Jezeer et al. 2018; Gidey et al. 2020; Yunusa et al. 2020; Roach et al. 2021).

Limited research has been undertaken on the delivery of labour efficiencies and socio-cultural benefits for smallholders enabled directly and indirectly by ecosystem services. In this paper we summarise the literature on the advantages and disadvantages of shade trees in coffee production. We describe the smallholder coffee production system in PNG and how production is socially and culturally embedded, and how coffee is part of a broader livelihood system which places significant time and financial demands on smallholder families. The purpose of the paper is to identify areas of potential labour savings for smallholders when growing coffee under shade trees and to stimulate further interest and research in this topic in the effort to find more sustainable and resilient production systems for smallholder coffee farmers.

Smallholder coffee production, shade trees and ecosystem services: a brief review of the literature

Although coffee trees evolved as a forest understorey, when grown as a plantation crop, high yields per hectare can be achieved under intensive production. This is typically associated with modern management techniques using selectively bred high yielding varieties, high planting densities, considerable use of external inputs, particularly fertilisers, and intensive shade management or shade elimination (Maestri and Santos Barros 1977; Muschler 2009). In contrast, smallholder production is often associated with lower yields, fewer external inputs and low inputs of labour (Muschler 2009).

However, there are economic and environmental trade-offs between unshaded and shaded coffee (Herandez-Aguilera et al. 2019). According to Muschler (2009), in unshaded or low shade production systems, the trade-off is cumulative environmental degradation. On the negative side for shaded systems, overshading is likely to lead to declining yields because of greater stimulation of vegetative growth rather than reproductive growth and berry production (DaMatta 2004). Also, Beer (1987) suggested that shade trees may damage the understorey crop when they are pruned or harvested, obstruct crop management, promote pathogens, insect pests and adverse environmental conditions; they can also compete for soil moisture and nutrients.

Unshaded, intensive production of coffee is not practised by most coffee smallholders in the developing world. Smallholder producers typically grow traditional coffee varieties, planted at lower densities under varying levels of unmanaged shade using low-input farming strategies, including few or no external inputs and low inputs of labour. The trade-off in this production system is high yields per hectare; instead, smallholders are satisfied earning more modest incomes with minimal labour inputs and other external inputs.

Much research has been undertaken on the ecosystem services shade trees provide in coffee production and how these can facilitate sustainable environments for smallholder coffee producers. Ecosystem services, defined by Haines-Young and Potschin (2018), that can contribute to the overall productivity, sustainability and resilience of smallholder farming systems include:

  1. 1.

    Provisioning services comprising material outputs for human benefit such as nutrition, materials and energy;

  2. 2.

    Regulation and maintenance services (e.g., of physical, chemical and biological conditions such as micro-climate, soil health and pest and disease control);

  3. 3.

    Socio-cultural services (e.g., spiritual, symbolic and physical interactions that improve mental well-being).

Provisioning services

Coffee provisioning services in agroforestry systems consist of physical outputs for human benefit such as coffee crop, nutrition, materials and energy. Examples include timber for house construction, biofuels for cooking and heating, foods (vegetables, fruit, nuts and honey), ‘bush’ medicines and ornamental plants (Ickowitz et al. 2021). These material outputs can be consumed by the household itself, sold to generate supplementary income or channelled into the indigenous or social economy to support community and socio-cultural activities. They also perform an insurance role by maintaining cash income during periods of depressed coffee prices (Albertin and Nair 2004: 444). Therefore, shaded coffee gardens are multiple-use agroforestry systems generating returns across both the subsistence and cash economies, as well as the social economy. Many of these alternative returns and values are difficult to quantify and are often ignored in analyses of export crop production (Ponette-Gonzalez 2007; Curry and Koczberski 2012; see Rafflegeau et al. 2023).

Regulation and maintenance services

Numerous studies have investigated regulation and maintenance ecosystem services in coffee shade systems. In summary, shade trees that reduce light intensity to coffee by approximately one-third can provide the following regulation and maintenance ecosystem services in the low-input smallholder production system:

  1. 1.

    An improvement in crop physiology, resulting in an extended productive life of coffee trees (Beer 1987; Lin 2009) and increased resilience to pests and diseases (Schroth et al. 2000; Soto-Pinto et al. 2002; Vega et al. 2015).

  2. 2.

    A physical environment more suitable for coffee: more constant ambient temperatures and humidity (Morais et al. 2006; Muschler 2009; Bote and Struik 2011); increased light use efficiency (Charbonnier et al. 2017); physical protection (Stigter et al. 2002); weed control (Bourke 1985; De Silva and Tisdell 1990; Njoroge 1994; Soto-Pinto et al. 2002); soil and water conservation (Blanco Sepúlveda and Aguilar Carrillo 2015; Meylan et al. 2017); increased soil organic matter and nutrient recycling (Prabhakaran Nair 2010); and more efficient nutrient acquisition (Borden et al. 2020).

  3. 3.

    An environment less suitable for many pests and diseases of coffee (Staver et al. 2001); but more suitable for a greater diversity of pollinators and natural enemies of coffee pests and diseases (e.g. Perfecto et al. 2004; Vandermeer et al. 2010; Karp et al. 2013; Mariño et al. 2016; Cerda et al. 2017; Nesper et al. 2017; Escobar-Ramirez et al. 2019; Durand-Bessart et al. 2020; Campera et al. 2022; Ambele et al. 2023).

  4. 4.

    Possibly, greater control of phenology of flowering (Beer 1987), more effective pollination (Roubik 2002; Klein et al. 2003; Ricketts 2004) and production of larger, denser and thus higher value coffee beans (Morais al. 2006; Bote and Struik 2011; Pinard et al. 2014).

Socio-cultural services

Socio-cultural ecosystem services provided in coffee and cocoa agroforestry systems have been identified in relation to biodiversity, and the ritual and aesthetic contributions these diverse systems make to households (for a general overview of the literature on cultural ecosystem services, see Milcu et al. 2013). Bucheli and Bokelmann (2017) found that coffee agroforestry provided a cultural heritage service through connection to the land and elders passing on their knowledge of the land and species to younger generations for preserving culture. Agroforestry systems provide socio-economic and cultural benefits such as resilience to market fluctuations and climate change, stabilising the environment and incomes, and strengthening food security (Mortimer et al. 2018; Singh et al. 2023).

Using a case study from PNG, we introduce labour efficiencies as a form of socio-cultural ecosystem service. We investigate how shade-grown coffee has the potential to improve labour efficiencies in a smallholder low-input production system while improving yield and coffee quality.

An overview of smallholder coffee production in PNG

Coffee is PNG’s second largest export crop, 85% of which is produced by smallholders (CIC 2008). PNG smallholder coffee growers, like smallholder farmers around the world, have very small holdings of coffee (approx. 500 trees or less – Imbun 2014), grow coffee under varying shade levels, use few external inputs and rely mostly on family labour. Coffee income pays for health and education and other general livelihood expenses, and is also channelled into the indigenous exchange economy. It is also a form of insurance: (i) coffee is more drought tolerant than vegetable crops; (ii) it provides income and food security by enabling store food purchases during times of environmental stress (Allen et al. 2001); and (iii) planting coffee shores-up land claims and ‘ownership’ (Imbun 2014).

The smallholder livelihood system is comprised of a diverse portfolio of activities including coffee production, food gardening for household consumption and marketing, and often very small-scale businesses such as poultry production and retailing of store foods and other goods. Like for oil palm and cocoa, socio-cultural activities remain important and are embedded in the smallholder livelihood system (Curry et al. 2007). A consequence of maintaining a diverse portfolio of livelihoods is that labour inputs in coffee are limited.

Worldwide, smallholder coffee farmers have developed a range of production strategies using various shade species and levels of shading. Toledo and Moguel (2012) identified five typologies of coffee production landscapes based on vegetation structure, variety and composition of species, and the impact of human manipulation. These landscapes range from a traditional ‘rustic’ system where coffee trees are simply inserted into a native forest of multiple plant species, to sun coffee, which is a monoculture of unshaded coffee trees (Fig. 1).

Fig. 1
figure 1

(Source: Toledo and Moguel 2012: 357; reprinted with permission of the publisher Taylor & Francis Ltd, htt1r//www.tandfonline.com)

The five main coffee producing landscapes distinguished by vegetation structure, species variety, and composition, as well as by the impact of human manipulation.

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Using Toledo and Moguel’s (2012) system of classification (Fig. 1), smallholder coffee production in highlands PNG would lie between ‘commercial polyculture’ and ‘traditional polyculture’. Smallholder coffee gardens have transitioned from ‘commercial polyculture’ when they were established initially about 50 years ago into a ‘traditional polyculture’ through long-term low maintenance and the adoption of intercropping with food crops and a polyculture of tree species (Bourke 1985). The dominant shade species in the typical smallholder coffee garden is Casuarina oligodon, a nitrogen-fixing tree endemic to the highlands of PNG. It has been used as a fallow species in subsistence food gardens for many centuries (Bourke 1997) and its integration into coffee plantings in PNG has been shown to increase coffee yields significantly (Yunusa et al. 2020).

Through time, shade levels in smallholder coffee gardens have declined as shade trees have been removed to allow for cultivation of food crops or been felled for timber or firewood and not replaced (Fig. 2) (Afolami and Ezebilo 2021). Yields under unshaded coffee in the PNG highlands are lower than what is usually achieved by smallholder shaded coffee because, in the absence of fertiliser applications, unshaded coffee trees suffer from overbearing dieback resulting in biennial slumps in yield (Talopa 2003).

Fig. 2
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 A partly shaded coffee garden, typical of many smallholder coffee gardens in the highlands of PNG

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A major threat to coffee in the PNG highlands has been the arrival in February 2017 of the devastating coffee pest, Coffee Berry Borer (CBB) (Hypothenemus hampei). It is not yet known what the full impact of this pest will be on coffee production, but smallholders were experiencing significant crop losses in 2023 in areas where infestation rates were high (CIC 2023; also Newton 2020). While agricultural extension is being ramped up to manage this pest, it is not yet known if smallholders will commit the necessary labour to manage this pest.

We argue four main points:

  • The low-input system of production is an enduring aspect of smallholder production in PNG, and in many other parts of the developing world, because it is socially and culturally embedded in local communities in ways that generate socio-cultural value and enable a suite of livelihood activities to be maintained;

  • The social embeddedness of smallholder coffee production within the context of a diverse livelihood system means that smallholders are likely to be highly resistant to extension efforts that seek to promote the adoption of high-input production strategies and technologies;

  • Shade-managed coffee is highly appropriate for smallholders pursuing low-input production strategies because it has the potential to generate ecosystem services that can improve labour efficiency and reduce the need for external inputs;

  • Shade management should be a focus of agricultural extension initiatives for smallholders pursuing low-input production strategies.

Methods

Data were collected between 2010 and 2012 at four field sites in Eastern Highlands Province as part of an ACIAR (Australian Centre for International Agricultural Research) project. The study sites of Asaro, Bena, Baira and Marawaka were selected based on accessibility to markets (see Curry et al. 2017: 14–23 for a full description of the study sites and methods). Asaro and Bena are within 20 km of the provincial capital of Goroka, and Baira and Marawaka are remote sites without road access (Fig. 3).

Fig. 3
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(Source: modified from CartoGIS Services, ANU College of Asia and the Pacific, Australian National University)

Field sites in Eastern Highlands Province.

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Data collection

Data were collected at the household level at the four field sites with household selection made with the assistance of village and clan leaders. Three data collection trips were made to Bena, Asaro and Marawaka and two fieldtrips to Baira.

Baseline household socio-economic surveys of 332 households across the four field sites collected data on household socio-demographic characteristics; access to land and labour; coffee holdings, production and management; and other subsistence and income activities (Table 1). This baseline survey included an inspection of each household’s main coffee garden and a questionnaire on farmer technical knowledge in coffee production. Regarding the latter, as part of the baseline survey, farmers were asked questions to assess their level of technical knowledge of coffee garden maintenance and nutrient resource management. They were also questioned on their level of understanding of shade tree management. An inspection of each farmer’s main coffee garden provided a snapshot of standards of coffee garden maintenance and practices, the types and condition of shade trees and the presence of intercrops. Observational data were collected during these inspections.

During the coffee season (the coffee flush period), time allocation surveys of a subset of 105 households from the baseline survey were undertaken over a period of 7–10 days (Table 1). Farm households were visited every second day and all adult members were questioned about how they allocated their time ‘yesterday’ and ‘today’. This enabled us to assess household labour allocation, the gender division of labour, livelihood activities, labour remuneration, access to and control over household labour and labour constraints. At Asaro and Bena an additional round of time allocation surveys was conducted with the same selected households during the coffee off-season (Table 1). These additional data enabled the study to assess differences in livelihood activities and labour demands between the coffee season and off-season.

Table 1 Number of surveys conducted at each study site
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Results

Coffee garden maintenance

For all maintenance categories, most smallholder coffee gardens were categorised as ‘adequate’ and few as ‘very good’ (Fig. 4). Most gardens had shade trees and nutrition levels were ‘adequate’ or ‘good’. Some households at the accessible sites of Asaro and Bena applied inorganic fertiliser, but its use was incidental as farmers were primarily applying it to marketable food crops that were intercropped with their coffee. At Asaro and Bena, the sites with easy access to markets, three-quarters of all coffee gardens were intercropped, and of these gardens, 60% had up to 20% of the coffee garden area intercropped, and 27% had 20–40% of the area intercropped. Intercrops were grown in gaps in the shade canopy where shade trees had died or been removed.

Fig. 4
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Status of coffee garden maintenance

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Farmer technical knowledge

Smallholders’ technical knowledge of coffee husbandry and postharvest processing was low. For example, while 95% of smallholders knew that the most appropriate time to prune coffee trees was just after the main harvest season, only 36% were aware that the most appropriate time to prune shade trees was just prior to coffee flowering. Furthermore, few farmers understood the relationships between shade levels and the incidence of pests and diseases; of 281 farmers interviewed, only two answered correctly to all three questions on the effect of shade tree pruning on Green Scale, Pink Disease and Coffee Leaf Rust. Also, less than one-third of farmers were able to identify the characteristics of fully fermented beans.

Labour allocation

At all sites the immediate family working together was the primary labour strategy in coffee production (mean of 68% of households across the four sites), with a mean of 18% of households for the grower working alone (Fig. 5). Hired labour was the primary labour strategy at only one field site, Asaro, and then for only 8% of households. None of the other sites identified hired labour as a primary labour strategy. Together, these data highlight the importance of family labour in coffee production, and the very limited use of hired labour.

Fig. 5
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The first ranked labour strategy in coffee production as a percentage of households

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The labour allocation surveys conducted during the coffee season revealed key differences in how men and women allocate their time. Men spent more time than women in coffee production while women allocated more time than men to domestic chores, subsistence food production and market gardening (Fig. 6). Regarding coffee, women engaged in harvesting and post-harvest tasks while men had more responsibility for maintenance (e.g., drains, fencing and pruning) and marketing (Fig. 6). Figure 6 includes coffee activities conducted in both the household’s own coffee garden and gardens belonging to others. During the coffee season when labour demands were high, women played an important role in reciprocal labour exchange where they provided harvesting labour through social and kinship networks. Of their total time in coffee work, 17% was in labour exchange assisting other families, largely with harvesting coffee compared with 6% for men.

Fig. 6
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Time allocated to coffee activities during the coffee season at all sites, by gender (Note: ‘Not specified’ includes labour exchange activities that were unspecified)

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When comparing all smallholder activities occurring during the coffee season, community and cultural activities were allocated much more time by both men and women than any other activity (Fig. 7). One-third of women’s time and 42% of men’s time was allocated to community and cultural activities. Men allocated almost twice as much time to community and cultural activities as they did to coffee production, their second most important labour activity. For women, they spent almost twice as much time in community and cultural activities than in subsistence gardening, their second most important labour activity (Fig. 7).

Fig. 7
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Time allocated to coffee and other livelihood activities during the coffee season by gender, as a percentage of total time

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At the two accessible sites of Asaro and Bena where coffee season and off-season time allocation surveys were conducted, the proportions of household time allocated to community and cultural activities declined from 37% of total time in the coffee season to 27% in the off-season. Women’s involvement in coffee production declined from 22% of their time in the coffee season to 8% in the off-season (Fig. 8). In the off-season a larger share of their total time was devoted to subsistence gardening. Both men and women increased their allocation of time to market gardening and other economic activities during the coffee off-season. More time was also spent on domestic activities.

Fig. 8
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Time allocated to different livelihood activities during the coffee season and off-season by gender, at Asaro and Bena

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Constraints on coffee production

Smallholder households reported a range of constraints on coffee production including a lack of farm inputs such as tools, other equipment and agrochemicals (39% of households), labour shortages (30%), poor access to markets and low coffee prices (38%) (Table 2). While poor access to markets and low prices are largely beyond the control of farmers, labour shortages and low farm inputs can be partly addressed by enhancing ecosystem services. We return to this topic later in the paper.

Table 2 Major constraints on coffee production (Per cent of HHs).
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Discussion

In this section we first consider the key factors that limit the supply of labour and external inputs in coffee production. To do so, requires consideration of how the indigenous economy conditions the supply of labour and the amount of coffee income that is reinvested in production. Then we explore how ecosystem services delivered by appropriate shade tree species and cover can fulfill some of the labour and farm input roles in coffee production that are not met by the low input production strategy.

The smallholder livelihood system and labour allocation

Like cocoa growers in PNG (Curry et al. 2007; Scudder et al. 2022), coffee smallholders typically follow a low-input production strategy relying mainly on family labour with minimal or no applications of external inputs (Fig. 5) (Curry et al. 2017). Low inputs of labour and external inputs are recognised by smallholders themselves as major constraints on production (Table 2). These labour and input constraints lead farmers to tolerate relatively high crop losses to pests and diseases. While aware of the losses, they do little to control pests and diseases through labour or chemical inputs (Uniquest 2013). Therefore, under a low-input production strategy, yields are typically much lower than plantation yields where all the inputs are applied (Sengere 2016; Sengere et al. 2019).

Yet, coffee extension does not recognise the enduring nature of the low input production strategy and its resistance to change. Agronomic recommendations delivered through extension continue to promote high-input, capital-intensive plantation style production with an emphasis on yield per hectare and an implicit assumption that labour is not a constraint (Sitapai 2012; Scudder et al. 2022; also, Vanclay 2004 on extension that ignores farmers’ lifestyles). Extension strategies in PNG across all commodity crops have been premised on the view that smallholder farmers were moving from low-input farming to high-input ‘modern’ farming, and the purpose of extension was to facilitate this transition. However, the very high degree of resistance to technology adoption and to increasing labour inputs such as through using hired labour has long been a source of frustration for the coffee and cocoa industries and has led to farmers being labelled as ‘backward’ or ‘lazy’ (Curry et al. 2007, 2021). This perspective on smallholder production misrepresents farmers’ lifeworlds and values, and overlooks how farming practices are socially and culturally embedded.

Moreover, extension’s almost exclusive focus on the economic dimensions of coffee production fails to consider the opportunity costs of labour and other inputs associated with maintaining a suite of livelihood activities – coffee is just one of several livelihood activities. It also ignores the multiple uses and values of coffee gardens beyond coffee itself such as food production, timber, fuelwood and fibre to name a few.

Explaining the persistence of the low input farming strategy

Labour is a critical bottleneck in smallholder coffee production as evidenced by the fact that at all four study sites, labour was identified by smallholders in their top four constraints on coffee production (Table 2). Based on household interviews and survey data, the labour supply and farm input constraints appear to be an outcome of several interrelated factors. These include:

  1. 1.

    absolute shortages of family labour;

  2. 2.

    the competing demands on labour from alternative livelihoods;

  3. 3.

    the underutilisation of household labour; and.

  4. 4.

    the social embeddedness of labour and production.

Absolute labour shortages of family labour can be a problem for some households such as elderly households without co-resident adult offspring and households with dependants too young to work. Usually, however, such constraints are not common because most elderly or young households have adult children or siblings, respectively, living nearby. In contrast, maintaining a portfolio of livelihoods, as identified in the time allocation survey, can limit the time available for coffee production (Fig. 7). These livelihood activities include not only coffee but also subsistence food production, production and local marketing of fresh garden produce and small-scale businesses which often operate intermittently. Thus, labour inputs in coffee reflect the opportunity costs of labour in a diverse range of farm and non-farm livelihoods (Curry et al. 2007; McKillop and Wood 2010: 28).

While absolute labour shortages and competing demands for labour may partly explain labour shortages, they do not explain why family labour is not fully utilised, nor the very limited use of hired labour. Also, they do not explain why farm families reinvest so little of their coffee income in their coffee gardens. To understand why this is so, we must consider gender relations and the social embeddedness of coffee production.

Underutilisation of labour

Intra-household relations, particularly gender relations, determine how household labour is allocated and remunerated (Curry et al. 2017). In PNG, export cash cropping is the domain of men, and while women contribute significantly to harvesting and processing, their primary focus is garden food production both for subsistence needs and marketing. Generally, men control the income earned from women’s labour in export crop production. Studies since the 1980s have shown that women’s labour input alone in export crop production may not give them secure rights to the income generated from their labour, often resulting in gendered conflicts over women’s labour and remuneration, particularly if men have not allocated women sufficient income to meet household needs (e.g., Strathern 1982; Grossman 1984; Sexton 1986; Johnson 1988; Collett 1992; Overfield 1998; Koczberski 2007; Curry et al. 2019). Gendered conflicts over the payment of labour can have negative impacts on the quantity and quality of smallholder production. For example, Overfield (1998) in a study of coffee production in the Benabena District, of Eastern Highlands Province, PNG, argued that the poor returns to women’s labour constrained the supply of female labour in coffee production to the extent that smallholder production and incomes were reduced significantly.

Social embeddedness of labour and production

While the financial opportunity costs of alternative livelihood options including gendered opportunity costs are important determinants of labour supply and external farm inputs in coffee production, the social opportunity costs are also important. Investments of time, labour and income in activities to maintain and strengthen the indigenous socio-economy and community are also critically important (Curry and Koczberski 2012; Curry et al. 2015). An exclusive focus on the economic dimensions of coffee production overlooks the broader socio-cultural context and associated values surrounding the deployment of labour and income (Ponette-González 2007). It is the social embeddedness of labour and production that explains the resilience and persistence of the low input production strategy.

Community and cultural activities were allocated much more time by households in our study than any other activity (Sillitoe 2010: 341–343 reported similar findings amongst the Wola of the Southern Highlands). Such activities include participation in, and contributions to, bride prices and funeral ceremonies, church and community activities, reciprocating with friends or relatives through labour and wealth (cash earned from coffee) exchange and ‘leisure’ pursuits (Curry et al. 2017). Garden food crops and pigs, and the embodied labour in their production, are also channelled into socio-cultural and religious events and networks.

The time allocated to community and cultural activities was significantly higher during the busy coffee season compared with the off-season. The higher cash incomes during the coffee season are harnessed for investment in the indigenous exchange or social economy. The increase in socio-cultural activities during the coffee season has been noted previously (Grossman 1984) and a similar phenomenon has been identified in oil palm in PNG where socio-cultural activities amongst village smallholders increase in frequency following monthly oil palm paydays (Curry 2003; see also De Silva and Tisdell 1990; Scudder et al. 2022).

While reciprocal labour arrangements were important during the coffee season and within the context of indigenous exchange, the use of hired labour was extremely limited at all sites. This is because labour arrangements remain very much kinship-based and within the realm of indigenous exchange. Hired labour challenges these fundamental principles and few smallholders countenanced a labour market in coffee production. While labour exchange by women and, to a lesser extent by men, helps alleviate labour shortages experienced by some households during the coffee harvesting season, its social value resides in its importance as a mechanism for building social capital (Curry and Koczberski 2012). Such exchange transactions also include the gifting of harvesting rounds. These exchange relationships are social investments that establish trust, build or maintain social relationships and strengthen common values and group identity (for a fuller discussion of the social value of labour, see Curry and Koczberski 2012; Barnes-Mauthe et al. 2015). Traditionally, they also served an important insurance role for individuals and groups by enabling access to the resources of others during periods when food security was threatened by, for example, extreme weather events.

Shade and labour

The very limited supply of labour in coffee due to competing demands for labour from alternative livelihoods, the gendered nature of export crop production, and the limited reinvestment of coffee income in external farm inputs, means there is limited scope to improve farm productivity under the low input production strategy. However, natural capital or what might be termed ‘natural technologies’ in the form of ecosystems services delivered by appropriate shade levels and shade tree species could partly meet these shortfalls.

We propose that an appropriate shade level and shade tree species in coffee can fulfill an unmet labour role and partly address the deficit in external inputs to improve coffee productivity, particularly labour efficiency. This could produce positive outcomes for livelihood security and smallholders’ capacity to engage in the social economy.

Ecosystem services that improve labour efficiency and/or provide ‘free’ or low cost inputs are likely to be attractive to smallholders. This is providing they contribute to, rather than challenge, the sustainability of the low-input production strategy that enables smallholder families and communities to maintain indigenous socio-cultural and economic values and diverse livelihoods. Regulation and maintenance ecosystem services are a form of natural technology that can improve the efficiency of smallholder labour, in much the same way that tools and external inputs improve labour efficiency and returns to labour (Fig. 9). For example, weed suppression from direct shading and from shade tree mulch reduces the need for labour for weeding or for herbicide (Bourke 1985; De Silva and Tisdell 1990; Njoroge 1994; Soto-Pinto et al. 2002). At the same time, it improves access to coffee trees for harvesting and pruning, leading to more efficient utilisation of maintenance and harvesting labour.

Fig. 9
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Increased labour efficiencies in coffee production from the application of good shade management practices

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Shade’s potential to increase synchronisation of coffee flowering, as suggested by Beer (1987), could also improve labour efficiency. With a shorter coffee season in which the annual production of coffee berries is concentrated, the deployment of labour across different livelihoods would be more efficient with greater temporal specialisation of labour in particular livelihood activities. This is especially true for women where different livelihood activities, particularly food crops, compete for women’s labour (Curry et al. 2019).

Whether smallholders would respond to extension advice and commit additional labour to shade pruning just prior to coffee flowering seems unlikely. However, in the context of CBB, the incentives to manage shade may increase. Crop sanitation with fortnightly harvesting is the most effective control strategy for CBB (Aristizábal 2018); Infante 2018) and is currently the recommended method of CBB control for smallholders in PNG. With crop sanitation, bean quality improves because of lower CBB infestation rates and because frequent harvesting leads to a reduction in overripe berries (Aristizábal 2018). Although more labour is required to implement crop sanitation, crop losses (weight and quality) can be very high under high CBB infestation rates, and without some level of sanitation, coffee production may become unviable in PNG. With appropriate shade, sanitation labour to control CBB can be made more efficient in two main ways:

  1. 1.

    shade-induced weed suppression giving easier access to coffee trees for harvesting and sanitation, particularly the berries on the lower branches that may be hidden by tall weeds; and

  2. 2.

    with timely shade pruning, greater synchrony of flowering enabling a final ‘strip pick’ of all berries at the end of the coffee season. This would reduce CBB reproduction and therefore through time reduce CBB infestation levels. Complete removal of all berries is the only method guaranteed to disrupt the pest’s life cycle (Vega et al. 2015).

The second point above, would be difficult to achieve and require large investments in extension. Smallholders would be unlikely to increase their labour inputs in the absence of CBB. However, given the predicted crop losses due to CBB, some smallholders may be encouraged to provide additional labour for CBB control. This remains to be seen.

Shade and smallholder extension services

Despite extensive research on the ecosystem services provided by shade trees in coffee and other export crops, few extension agencies and smallholders in PNG appreciate the potential economic, environmental and socio-cultural benefits of appropriate shade levels in a low-input production strategy. Few are aware of how, with comparatively low inputs of labour, effectively managed shade trees can elevate the productivity of their coffee trees while also providing them with an additional source of income and a sustainable and a more climate change resilient system of production. Also, shaded coffee has marketing advantages as many certifying organisations have a requirement for shade (DaMatta 2004). The current output of research on the use of shade trees in commercial coffee production should be of particular interest to those providing extension support and other resources to smallholder coffee growers practising low-input production strategies.

Providing extension to smallholders to facilitate a transition from low-input to high-input intensive mono-cropping of coffee does not recognise the very strong social embeddedness of coffee production that makes the low-input production strategy highly resistant to change. To be effective, extension strategies must accommodate low-input production strategies to deliver financial and social returns. This means they should encompass holistic approaches to smallholder coffee extension that recognise the diverse livelihoods and socio-cultural priorities of most smallholder families. The social returns enabled by the low input production strategy such as time and coffee income devoted to socio-cultural and community activities are all about an indigenously defined quality of life, which gives the low input production strategy its robustness. Thus, there should be a focus on strategies to improve and sustain livelihoods in what is defined by Toledo and Moguel (2012) as a traditional polyculture system of production. For example, recommendations should be provided on incorporating shade trees and crops that provide food and resources such as vegetables, fruits and nuts, timber and firewood, fibre, and ornamental and medicinal plants, that diversify household income and livelihoods. Shade management should be an integral part of extension to promote labour-efficient production strategies that facilitate sustainable production, produce better quality and higher value coffee beans while strengthening livelihood resilience, indigenous values, practices and cultural infrastructure.

This preliminary research investigated how ecosystem services delivered by effective shade management might fulfil a labour role in coffee garden maintenance and partly address an unmet need for external farm inputs such as fertiliser, pest and disease control and weedicides. Our research suggests several broad areas for further research including the adoption of a more holistic perspective that encompasses the multiple use values of coffee gardens, recognises that coffee is part of a suite of livelihoods, and understands the implications for quality of life arising from the social and cultural embeddedness of coffee production. Key areas warranting further research include:

  1. 1.

    The labour efficiencies generated under different shade levels and shade species composition;

  2. 2.

    Assessments of the true productive value of coffee gardens that consider the multiple use values of coffee gardens (e.g. values for food, fibre and energy), and how to enhance these values (e.g. intercropping coffee with food crops);

  3. 3.

    Assessments of the trade-offs between coffee and alternative livelihoods to optimise the mix of livelihoods for delivering economic and social outcomes for smallholder families and their communities.

Conclusions

The paper identified the labour and farm input shortages typical of smallholder export crop production in PNG and in much of the developing world. Labour shortages were due to a range of factors including: barriers to mobilising women’s labour; the competing demands on labour arising from maintaining a portfolio of livelihoods; the absence of a market in hired labour; and the time, labour and income demands of the indigenous socio-economy. Like subsistence food production, coffee is socially and culturally embedded with relations of production determined by kinship rather than a labour market, with much of the coffee income channelled into the indigenous exchange economy for bride prices, mortuary payments and related socio-cultural and community activities. During the coffee season when there is more cash around, the social embeddedness of coffee production leads to socio-cultural activities increasing in scale with more than double the amount of time allocated to community and cultural activities than to coffee itself. The demands of the social economy on labour and coffee income, which are tied to quality of life, mean that labour for coffee garden maintenance and coffee income to fund external inputs are in short supply. Extension efforts over decades to shift farmers to high input farming have failed because they have not recognised the role of the low input production strategy for enabling a way of life where indigenous socio-cultural and economic values are able to persist and flourish.

From the recognition that the low input production strategy is enduring for socio-cultural reasons, we explored how ecosystem services delivered with improved shading might fulfil some labour and other farm input roles. Knowledge of the economic, environmental and socio-cultural benefits that can be provided by ecosystem services in agroforestry must be communicated to smallholder farmers practising the low-input production strategy. Although further research is required in this area, we have pointed out areas in which labour efficiencies could be improved through enhancing ecosystem services through using shade.

Finally, the paper has highlighted the importance of farmer extension training not being based on top-down, imported extension models that assume coffee production occurs in a vacuum independent of the lifeworld of smallholders and that labour is not a constraint. Instead, as also suggested by Valencia et al. (2015) and Scudder et al. (2022), extension materials should be co-designed with smallholders to ensure that local knowledge, and indigenous socio-cultural and economic values are not undermined by extension. An extension approach based on the low-input production strategy must highlight to smallholders the many unobservable physical processes, such as nitrogen fixation, nutrient cycling, weed suppression, biodiversity and pest and disease control, as well as social complexes such as the gendered nature of coffee production and income distribution which may limit the participation of women in coffee production.