Our group prepared the database on agroforestry studies for Mexico in 2022, included 730 studies. Only fifty were carried out in Mexican Arid America (6.8%). The spatial distribution of the inventoried publications is in Fig. 3. The map shows the concentration of studies in southeastern Mexico.

Source: Based on the inventory of agri-silvicultures for Mexico. Lambert Conformal Conic Projection, Datum WGS 1984

Geographical distribution of publications about agri-silvicultures in Mexico, updated to 2022.

The database on ASC studies included articles, book chapters, a report, and a journalistic note. These documents describe 118 places where agri-silvicultures in Mexican Arid America exist. The number of cases in Baja California Sur, Chihuahua, Aguascalientes, Coahuila, and San Luis Potosí stands out. More publications are for Coahuila, Sonora, and Nuevo León states (Fig. 4).

Source: Based on the inventory of Agri-silviculture for Mexican Arid America. Lambert Conformal Conic Projection, Datum WGS 1984

Typology of Agri-silvicultures in Mexican Arid America.

The analysis of the history of agri-silvicultures in Mexican Arid America and their interactions with aridity allowed us to propose a more detailed typology: Agrosilvopastoral, Silvopastoral, Homegardens, Milpa, Oasis, Mesquite and Huisache, and Natives. The first four categories correspond to traditional forms of agroforestry systems [3, 82] but with particularities that we highlight in every case. The following three (Oasis, Mesquite and Huisache, and Natives) describe relationships identified as characteristic of Mexican Arid America due to their specific interactions with situated biocultural diversity (Fig. 4).

We defined agri-silvopastoral types as the relationship promoted by cultural groups between wild and cultivated diversity, and livestock (Fig. 5). This system takes advantage of different spaces, the plots and backyards, to grow fruit trees, vegetables, fodder and maizefield crops, poultry, and other domestic animals, and the pastures to take advantage of, protect, and promote wild or introduced fodder, to raise livestock. In these areas, food produced for humans competes with food intended to feed livestock. The case of maize is illustrative; it has gone from human food to fodder. Families decide about the vocation of their spaces by the need to integrate into the agroindustrial system through some intensive practices such as cattle stabling to speed up fattening and obtain good-weight calves for sale [83]. Figure 5B shows in Sonora state a combination of mesquites, vinoramas, chírahuis, and other native trees that provide forage, with cultivated sorghum in a plot that years ago was used to grow maize and squash (see Table 2 for scientific names).

Agri-silvopastoral. A. Rainfed maize, in the background mesquite and native vegetation, for dual-purpose cattle feed and fresh cheese production in Cobachi, Sonora, Mexico, August 2013. B Rainfed forage sorghum, in the background mesquite, for dual-purpose cattle feeding and fresh cheese production in Pueblo de Álamos, Sonora, Mexico, November 2014. Photographs by Araceli Andablo

In Coahuila, agriculture is seasonal, and the main food crops are maize and beans. Families introduced forage such as sorghum, oats, and wheat to make silos for the dry months; in the backyard, they grow squash, coriander, chili, lettuce, radish, nopales, tomato, and chard; and also have fruit trees such as plum, peach, pomegranate, apple, apricot, and lemon (Table 2). The domestic animals that they manage are cattle, sheep, goats, pigs, horses, mules, donkeys, and poultry (Table 2). The principal livestock product is milk, but they also obtain meat and eggs [84].

Coahuila's agri-silvicultures are for self-consumption, and people also sell the surplus. Salaried work in industries close to the urban area complements the income obtained from agriculture. Families estimate that, on average, a quarter of the production goes to the market. One of the principal vulnerabilities that families identify is the loss of agricultural vocation due to migration to cities. In addition, the constant and prolonged droughts typical of the region and pests make production difficult [85].

In Aguascalientes, an experimental study reported the rotation of sorghum and beans with live barriers of nopal and guaje. The Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias (INIFAP) tested agroforestry strategies for controlling soil erosion in arid conditions with high-intensity and short-duration rainfall [86].

Silvopastoral practices refer to the relationship promoted by cultural groups between wild forage, introduced grasses, and livestock (Fig. 6). The link with local biodiversity is woven through cattle grazing. Spaniards introduced cattle to the Americas, but recently, the modernization process promoted genetic improvement by importing European breeds specialized in meat production. The ASC introduced these breeds into its herds but has adapted them to the arid and semiarid conditions and diversified their production [87]. To take advantage of these environments, they conserve nomadic management practices inherited from colonial times [88]. The pastures introduced by the Green Revolution are part of the strategies in these systems, with undesirable environmental consequences.

Silvopastoral. A Cows feed on nopales in the Sierra Huérfana, Pueblo de Álamos, Sonora, Mexico. May 2016. B Meadow with buffel in Tecoripa, Sonora, Mexico. March 2014. Photographs by Araceli Andablo

We recorded between 13 and 42 species in the grazing sites, with a dominance of the Fabaceae family, which contributes to soil regeneration by providing nitrogen. The main species reported are mesquite and huisache [89] (Table 2). In the sites studied, native grasses are essential. Buffel grass exists in the region, an invasive species that reduces native species diversity.

In this group, it is vital to highlight local ancestral management of the "feral or mesteño" cattle. Spaniards developed this management in the Bolsón de Mapimí region in the sixteenth century. This area is at the confluence of the States of  Durango, Coahuila, and Chihuahua. Due to the arid conditions that characterize it, 300 mm average annual precipitation, and vegetation microphyllous desert scrub, cattle ranching could not develop as in other places with better possibilities for cultivated or native forage wealth. In the Bolsón de Mapimí, the cattle became feral for two reasons: first, they could not be kept close to the haciendas due to the low pasture (agostadero) coefficient. The second argument is the constant irruptions of the native ethnic groups in the area did not allow the ranchers to guard their cattle. In this way, cattle grew freely in the area until it was peaceful at the end of the nineteenth century [88].

In these cattle regions, scholars identified recurrent droughts and the alteration of biodiversity caused by grazing. Thinning of the native vegetation to introduce buffel weakens the regenerative capacity of the diversity due to the low availability of nitrogen in the soil [89]. This introduced species has a great invasive potential to replace native biodiversity, affecting native grasslands and adjacent areas [77, 78]. A positive result reiterated in the case studies is the regenerative capacity of the Fabaceae family to face deforestation. Another possible alternative in sites with extreme aridity could be the feral management of livestock to avoid overexploitation of the rangeland.

Homegardens are identified mainly by their proximity to the family home, where cultivated and wild elements are maintained (Fig. 7). Families manage four to 46 species of fruit trees, vegetables, legumes, agaves, nopales, and other wild species (Table 2). The care given to native species such as maguey, mesquites, and cacti promotes their conservation. For example, in Sonora, maguey is germinated and grown in the homegardens until it can be transplanted to the plots [90]. Families, too, have domestic animals, cows, sheep, goats, turkeys, donkeys, horses, and hens, to obtain milk, cheese, meat, eggs, and transportation and cargo services [91].

Homegardens. A–C From Hilda's Homegarden in Pueblo de Álamos, Sonora, Mexico. July 2018. Photograph by Araceli Andablo

The objective of the homegarden is self-consumption and the occasional sale of surpluses. The families studied reported having income from other activities: employment as day laborers in agricultural fields, in tourism companies, other salaried jobs, sale of cheese, calves, bacanora,Footnote 6 migration, and, in the case of two Yaqui communities in Sonora, from renting their land [92, 93].

In arid urban sites, the presence of homegardens contributes to temperature regulation due to the concentration of humidity and shade [94]. Some families have developed strategies to solve problems related to climate and water, such as the reuse of gray water [95]. However, these practices face threats, such as land rental for the establishment of monocultures for export, which causes the loss of diversity and local knowledge about traditional crops; sanitary measures that restrict the presence of domestic animals in the family garden [93]; migration; droughts and frosts; pests and untimely flowering due to climate change; lack of generational replacement [95]. It was also identified that collective or community garden initiatives do not prosper as in the south of the country [96].

Milpas are systems where annual crops interact with forestry elements and wild ruderal species (Fig. 8). Families establish a relationship with biodiversity through their plots. These ASC develop soil conservation and recovery strategies in sites prone to erosion and use native species with thorns to build living fences in cultivation areas such as: ocotillo, palm, organ, mesquite, and other introduced species such as pinabete [97] (Table 2). The predominance of agroindustrial monocultures and politic that support productive specialization threaten the diversity of traditional milpa crops and promote the replacement of food crops with fodder [87].

Milpa. A, B Agricultural plots near Real de Catorce, San Luis Potosí, Mexico, December 2017. Photographs by Gerardo Hernández

In addition to cultivating domesticated species, they conserve other arboreal and ruderal species used as food, medicine, shade, and fencing. In the Tajos of Guanajuato, the people manage 72 species, 47 of which are native such as sage, garambullo, and pitayo, that they use as food and medicine [98] (Table 2). Mestizo collector groups are also located here, particularly in Aguascalientes, where at least 11 species of the genus Amaranthus are collected for food and medicine [99]. Corporate Agriculture threatens these practices by promoting monoculture and substituting food crops for fodder.

Oases are a type of colonial agroforestry management and are among the most studied in arid zones (Fig. 9). These ASC develop in natural wetlands in the desert, where cultivated elements inherited from the missionary era interact with fruit trees, livestock, and annual crops. Isolation of these systems contributes to conserving strategies adapted to aridity as complex irrigation systems and stratified crops for water and soil retention.

Oases. A and B Oasis en Baja California Sur, Mexico. Photographs by Enedely Vargas, 2017

Cariño et al. [100, p. 152] note that "oases are more than natural wetlands in deserts"; these sites constitute species conservation niches and the relics of management practices imported by the Jesuits from other arid zones in Asia and Europe [16]. The isolation of the Baja California peninsula has allowed the Rancheros, the cultural group finally colonized the region after the expulsion of the Jesuits, to conserve management strategies inherited from the missionary era for centuries. In Baja California Sur, The Rancheros cultivate up to 42 species in multiple strata with water retention and conduction management typical of oases, such as missionary olive, missionary grape, and quince [16] (Table 2).

In Quitovac, Sonora, where Pápagos (Tohono O'odham) survive, up to 139 species are in oasis plots: date palm, fig, lemon, orange, peach, and pineapple, among others [101]. The oases make a significant contribution to the food sovereignty of their inhabitants; they also constitute a relict of conservation of management adapted to and respectful of a fragile environmental balance that does not tolerate overexploitation. However, this fragility represents a significant risk in the face of modernizing ideologies and corporate exploitation that have affected the region since the expansion of the Green Revolution at the end of the last century [16, 100].

The Mesquite and Huisache types represent initiatives to reconnect with the trees that predominate in the scrublands of arid zones (Fig. 10). The case studies are in Baja California, Sonora, Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, and Guanajuato. People are revaluing the multipurpose function of these trees and other native species (Table 2) as food and fodder, for reforestation, to deal with recurring droughts and famines, for soil conservation and recovery, for medicinal purposes, as fuel, and for the production of furniture and handicrafts.

Mesquite and Huisache. A Mesquite orchards in Matamoros, Coahuila, Mexico. April 2023. Photography Ing. Samuel Atahualpa Ramírez Macías. B Pruning in mesquite orchards in Los Whiles, San Pedro de las Colonias, Coahuila, Mexico. December 2015. Photograph by Alejandro Moreno-Reséndez

People use the mesquite péchita (pod) to make flour, atole, and bread, an ancestral subsistence activity promoted by international and local organizations in the region. [52]. The Mesquite and huisache pods are fodder for cattle, and their flowers are melliferous [102]. These cases constitute a strategy to face environmental changes and contribute to rural families' food sovereignty. However, agricultural policies that favor corporate management threaten this agroforestry due to competition for water.

The cases grouped as Native stand out for the persistence of practices like hunting, fishing, and gathering of local species as essential activities for the subsistence of native groups of Mexican Arid America. The marginalizing conditions of these groups provoke a loss of ancestral knowledge about native biodiversity and abandonment of nomadism as a subsistence strategy and protecting their lands [103].

Sales-Colín et al. [104] reported that Makurahue (Guarijío) people cultivated 45 species in the ancient farming systems: Mahuechi, Verano, and Solar. They registered that the guarijíos gathered 58 species in their lands, too. People cultivated since pre-Hispanic times macuchi, a local species of tobacco (Table 2) [105].

In the case of the Raramuri rancherías of Chihuahua, most of their plots are on hillsides, where they grow mainly maize and at least five other species. In their homegardens, they report 12 species of fruit trees for self-consumption and the production of fruit preserves for sale. Hunting is very relevant to the Raramuri: they hunt seven minor and two major species, fish in rivers for six species, and collect 20 wild species (Table 2) [103, 106]. Raramuri people obtained from wild and weedy plants, on average, 21.9% of the annual biomass that they consumed [70].

The Seri (Comcáac) are probably the last cultural group today to subsist primarily on fishing and gathering. Felger and Mosser [107] reported in 1976 that the Seri people used at least 75 species for food and approximately 95 more in the traditional pharmacopeia. The incorporation of the ethnic group into modern life has caused the disorganization of their nomadic tradition and the integration of the Western diet into their way of subsistence. Therefore, the Seris people today face the loss of their food wealth and ancestral knowledge about their territory [108]. In 2015, Narchi et al. [109] reported 25 species used as medicine in various preparations, 12 species of marine origin, and 13 terrestrial plants (Table 2).

Threats to these cultures are migration, pollution due to tourism activities in the Tarahumara Sierra, and the water fight in the case of the Guarijíos in Sonora, and all ethnic groups face the loss of ancestral relationship with their lands practiced through the fishing, gathering, and hunting.