We analyzed spatial patterns of avocado frontier expansion in Michoacán, Mexico, before and after the implementation of NAFTA and assessed how the relative importance and interactions of spatial determinants explaining these patterns have changed during a 40-year period of turbulent socioeconomic and political change in Mexico. Four major insights emerged from our analysis. First, avocado frontier expansion increased substantially across time and space, most strongly post-NAFTA. Second, the expansion of avocado orchards during 1960–1974 was mainly related to accessibility and environmental factors, i.e., annual precipitation, distance to roads, distance to settlements, and slope, whereas during pre- and post-NAFTA periods, land tenure and annual mean temperature were important factors in determining frontier expansion. Third, potential future expansion areas are likely to shift into more marginal areas than currently, characterized by less precipitation, steeper slopes, and larger distances to settlements, roads, and rivers. This can result in less production potential and important economic repercussions for the livelihoods of small-scale farmers. Fourth, potential future avocado expansion areas will likely entail substantial environmental trade-offs, due to encroachment on important areas for crop wild relatives’ conservation, as well as on areas with high biological value and feasibility for ecological restoration. Considering the increasing demands for agricultural commodities that are rapidly transforming the spatial patterns of land-use change in globalized production systems, our results facilitate a better understanding of frontier expansion dynamics of commodity crops.
Effects of environmental conditions and accessibility on avocado frontier expansion
Distance to settlements was the major accessibility factor determining avocado expansion across the avocado belt in Michoacán during the three periods analyzed. Several studies have linked land-use change (e.g., deforestation for agricultural expansion) to more accessible, flat areas with high road and population density (Jakovac et al., 2017; Salonen et al., 2012; Verburg et al., 2014). Although we found that better accessibility increased the probability of avocado expansion, we also observed a clear trend towards the establishment of new avocado orchards in areas farther away from settlements, roads, and rivers, and with steeper slopes during pre- and post-NAFTA periods. This suggests that avocado frontier expansion is not only driving crop substitution and displacement of traditional crop systems distributed near settlements and local markets but also indicates that avocado orchards are expanding into more distant areas, resulting in pine-oak forest clearing in the region (Bravo-Espinosa et al., 2014). Displacement of shifting cultivation and replacement of forested areas driven by export-oriented crop production are processes observed also in other world regions, especially in Southeast Asia and sub-Saharan Africa, such as Vietnam (Meyfroidt et al., 2013), Congo (Ordway et al., 2017), or Cameroon (Ordway et al., 2019). Increased frontier expansion caused by global agricultural commodity booms can further lead to the marginalization of local small-scale farmers (Levers et al., 2021), negatively affecting their livelihoods by an increased vulnerability due to reduced productive potential and higher exposure to volatile and unstable global markets (Abid et al., 2016; Meyfroidt et al., 2014).
Effects of land tenure on avocado frontier expansion
We found that avocado orchards during pre- and post-NAFTA periods expanded mostly in private lands. Moreover, private lands under optimal conditions were more likely to be converted to avocado orchards, whereas in communal lands, most avocado expansion occurred under suboptimal conditions. Lands under a communal regime are less likely to change towards avocado production, mainly because decisions over land use must be based on the consensus of the community, as opposed to private landowners that have individual agency over their land; therefore, new avocado orchards on communal lands tend to be established on areas that are less productive (i.e., suboptimal) and where there are fewer conflicts among community members. When lucrative activities are involved in communal land use planning, conflict among stakeholders is the most common outcome (Perez-Llorente et al., 2019). It has been reported that land-use changes arise when communal lands are sold to both insiders or outsiders (DiGiano et al., 2013), especially as the reform of Article 27 of the Mexican Constitution in 1992 ended government obligations to redistribute land and authorized individualization and private titling of lands, which also disarticulated the social sector and affected land systems of communal property. The few well-organized communities in the region with strong governance have historically focused their resource management to forestry, preventing avocado expansion and land-use change in general, and thus protecting their natural resources and livelihoods (Barsimantov and Antezana, 2012; Orozco-Quintero and Davidson-Hunt, 2009).
However, for several communities throughout the avocado belt in Michoacán, avocado frontier expansion has resulted in profound land tenure regime changes, reigniting old conflicts over land titling, holding size, and land use (Barsimantov and Antezana, 2012). Moreover, post-NAFTA, economic incentives prompted by state and federal governments only favored large-scale commercial growers and agribusinesses, and small-scale farmers were increasingly left behind (Assies, 2008). The global avocado boom prompted by the implementation of NAFTA has increased and amplified the inequalities between large agribusinesses integrated into the global markets and local small-scale farmers facing land scarcity and lack of economic incentives (Orozco-Ramirez et al., 2017). This has further resulted in an increasing impoverishment of rural small-scale farmers, a disarticulation of local institutions, and has increased conflicts throughout the region (Ornelas, 2018). Such asymmetries in agency and power relations between actors were also observed in commodity frontiers in Argentina (de Waroux et al., 2018), Madagascar (Neimark et al., 2019), Laos (Junquera and Gret-Regamey, 2019; Ramcilovic-Suominen and Kotilainen, 2020), and Indonesia (Pichler, 2015), underlining the importance of land titling and land rights in global agricultural systems, which need to be considered in targeted and contextualized decision making.
Socio-environmental trade-offs and future development pathways
Our results revealed substantial socio-environmental impacts of the ongoing avocado production in Mexico, and thus support previous findings showing that avocado production in Michoacán has triggered deforestation, illegal logging, and landownership conflicts (De la Vega-Rivera and Merino-Perez, 2021; Perez-Llorente et al., 2019). We showed that new avocado orchards expanded into increasingly less suitable areas throughout the study region since 1974, and we expect that this trend will likely continue in the future. This process of marginalization can result in poverty traps for small-scale farmers (Barrett, 2008; Mastrangelo et al., 2019; Meyfroidt et al., 2013), increasing their vulnerability and impairing their ability to sustain their livelihoods. In addition, climate change trends modeled for the region are expected to negatively impact avocado production systems due to higher temperatures, lower precipitations, and more frequent extreme climate events (e.g., frosts and hail), further increasing the pressure on small-scale farmers (Charre-Medellín et al. 2021).
Although we observed that priority sites for biodiversity conservation were not strongly affected by past avocado frontier expansion, some important sites for crop wild relatives’ conservation have been and will likely be transformed into avocado orchards. Moreover, our results revealed that the avocado frontier is likely to expand into sites with high restoration feasibility, thus reducing the possibilities of maintaining and restoring the biological diversity and ecological functions of those sites. Our findings identified ongoing and future hotspots of avocado expansion that could potentially compromise the long-term preservation of the region’s biodiversity. For instance, the boundaries of protected areas — although effective — are already under high pressures, as well as several priority sites for biodiversity conservation and important sites for crop wild relatives’ conservation (Sanchez et al., 2019).
According to official census data, the total land devoted to avocados in 2018 was 175,014 ha, corresponding to an increase of 22,521 ha since 2011 (SIAP, 2018). Following our results, using a probability threshold of ≥ 0.7, suitable areas for potential avocado expansion only accounted for half of this area (11,827 ha). Yet, potential expansion in moderately suitable areas for production (threshold between < 0.7 and ≥ 0.5) accounted for 27,617 ha. This suggests that avocado expansion in the past years likely occurred in both suitable and less suitable areas. Avocado production and exports are expected to continue in the future, which will likely result in further expanding avocado frontiers providing that areas for production — even under suboptimal conditions — are still available. Yet, this scenario could change anytime. For instance, NAFTA’s transition into the United States–Mexico–Canada Agreement (USMCA) in 2018 raised concerns and increased tensions among the actors involved in the avocado industry. A potential hold-up in the ratification process was initially suggested, which would have put Mexico’s food export markets at risk. In the longer-term, it could also be possible that growing environmental concerns affect avocado demand on a global scale. Despite these concerns, the avocado industry has overcome several instabilities, such as the COVID-19 pandemic, underlining the strength of its supply chain and collaboration strategies (Lopez-Ridaura et al., 2021).
However, the environmental footprint of global avocado consumption patterns continues to exert serious pressures on local small-scale farmers, indigenous communities, and common property lands. A major concern is that as suitable lands for growing avocado become scarce, and the impacts on the environment are amplified, this system integrity can potentially be comprised. Moreover, these impacts can in turn be exacerbated in the future by reduced water availability, intense droughts, and higher susceptibility to pest invasions (Charre-Medellín et al. 2021; Chávez et al., 2019), by fluctuating market prices, changing consumer preferences, and by a fragile ecosystem facing a continuously more eroded genetic diversity of crops and crop wild relatives (Contreras-Toledo et al., 2018; Ford-Lloyd et al., 2011; Vincent et al., 2019).
In this study, we assessed the spatial patterns of avocado frontier expansion before and after NAFTA implementation based on environmental, land accessibility, and social factors determining that expansion. Aside from expansion, the intensification of land management is crucial to understand commodity frontier dynamics as both processes usually occur together in regions characterized by export-oriented crop production (Barretto et al., 2013; Byerlee et al., 2014; Varkkey et al., 2018; Zabel et al., 2019). In Michoacán, the increasing market demands, and rising prices have stimulated the continued expansion of the avocado frontier during the past three decades and have promoted land-use intensification to increase avocado yields to meet market demands. As land for agricultural expansion becomes scarce, agricultural intensification is likely to increase (Barretto et al., 2013; Lambin and Meyfroidt, 2011; Zabel et al., 2019). Evaluating the spatiotemporal patterns of land-use intensification across the entire avocado belt region was beyond the scope of this analysis due to major data gaps about system inputs (e.g., capital per land area, cropping frequency) and outputs (e.g., agricultural yields, production volumes). However, including intensification patterns and change trajectories in our analysis would have allowed us to further improve the understanding of land-system changes and the underlying factors in this dynamic commodity frontier region.
Context-specific studies linking local scale processes to global international trade dynamics by means of spatially explicit models are still rare, although they could greatly improve our understanding of how telecoupled systems interact (Friis et al., 2016; Gasparri et al., 2016; Yu et al., 2013). Here, we addressed a set of important environmental, land accessibility and social factors determining avocado expansion. Yet, a clear understanding of the local underlying factors driving conflicts and land-use change dynamics throughout the avocado belt is still necessary. Our analysis could be greatly improved by incorporating economic (e.g., market prices for agricultural exports, export volumes, GDP growth, labor force), institutional (e.g., trade policies, domestic agricultural policies, trade tariffs changes), and other social (e.g., access to technology) drivers of avocado frontier expansion, which we could not incorporate due to data restrictions. Moreover, addressing flows, feedbacks, spillovers, and trade-offs along the avocado supply chain in a spatially explicit way and linking those processes to local land-use changes would offer an exciting opportunity to accurately quantify the environmental footprint of avocado production and to track the value chain from production to consumption (da Silva et al., 2021). Such approaches fall beyond the scope of the present study.
In this study, we assessed avocado frontier expansion for three periods using the avocado frontier inventory available for years 1974, 1995, and 2011. Yet, avocado production in Mexico and demand from elsewhere has continued to increase since then (Cho et al., 2021; Denvir et al., 2021). One key step towards more reliably assessing the impacts and trade-offs the avocado industry has left on this major production region is to generate an updated wall-to-wall version of the avocado inventory. This would allow validating the potential expansion areas predicted by our model against the actual avocado orchards currently found in Michoacán and in adjacent states such as Jalisco, a new and rising production hotspot. It would further allow for re-assessing the importance of spatial determinants explaining expansion patterns. Also, mapping settlement expansion since 1960 would allow to better capture settlement expansion dynamics, to refine our models’ predictions, and to deepen our understanding of how this spatial determinant has influenced avocado expansion.
Finally, by using XGBoost and SHAP values, we were able to better understand the interaction effects between land tenure and environmental and accessibility variables, which thus allowed us to gain a unique insight into some underlaying processes of this expanding frontier in central Mexico. As future research, it would be useful to integrate and compare the present results with other modeling approaches based on cellular automata (Soares et al., 2006) or other land allocation models that allow incorporating dynamic variables (Verburg et al., 2013).
Landscape configuration reflects historical effects of land-use changes prompted by public policies. Avocado frontier expansion took place in a context of land policy and land tenure reforms in Mexico, but also as part of a wider context of agricultural development and trade policies (Assies, 2008). As such, the avocado industry has been shaped by context-specific circumstances and has been mediated by national and global external forces. Our results further foster and support the discussion about the need for improving the representation of small-scale farmers in policies, regulations, and governance, and for strengthening communal land rights.
First, policies oriented towards increasing the integration of small-scale farmers into the agricultural sector are highly needed, as well as the design and implementation of strategies and incentives aimed at supporting small-scale farmers producing subsistence and domestic-oriented crops. Second, as avocado production is highly spatially concentrated, and communal lands are a key component for maintaining natural areas and avoiding conversion to avocado orchards, efforts to minimize the socio-ecological impacts of the international trade of avocado should focus on the reinforcement of communal land rights and local governance (Barsimantov and Antezana, 2012; Denvir et al., 2021). Such actions could improve the situation for the environment and small-scale farmers and could help to sustainably manage and protect biodiversity-rich areas currently at risk by expanding avocado frontiers (Sanchez et al., 2019). Third, government policy schemes could tax the environmental footprint of land converted to avocado orchards, potentially benefiting small-scale farmers already using degraded lands, over large ones clearing large areas of forests in regions with suitable environmental conditions. Fourth, the identification and mapping of supply chain actors and connections is crucial to accurately assess the environmental and social risks embedded in the production, consumption, and trade of agricultural commodities (Godar et al., 2016). Efforts to promote avocado supply-chain transparency and sustainability should focus on improving conventional regulatory frameworks and governance through multi-stakeholder initiatives (Cho et al., 2021).
Finally, fair and more equitable sharing of benefits arising from agricultural trade commodities, particularly among small-scale farmers, is essential to move towards more sustainable, efficient, and inclusive telecoupled food systems.