Vanishing of the mighty tunales of central Mexico: A 5-century history of landscape change

When one thinks of arid lands in the Americas, an image of cacti usually comes to mind. Among them, nopales (species of the genus Opuntia), regardless of other types of cacti (columnar, barrel, globose, or candelabriform), are widespread and iconic in these ecosystems. Nopales are usually conceived as midsized shrubs interspersed among other shrubby plants, but few people think of them as thick forests several-meter tall. Such forests were indeed the signature feature of the southern part of the Mexican Plateau before the mid-16th century (Ahumada, 1566).

Soon after the Spanish took over Tenochtitlan in 1521, they began to explore in all directions and appropriate as much land as they could. When in the mid-16th century Spanish explorers were shown silver nuggets and taken to the Cerro de la Bufa (by the current city of Zacatecas), efforts to establish a travel route from there to the city of Mexico soon began (Powell, 1977). Spanish expansion into the southern part of the Mexican Plateau was met with fierce opposition by the bellicose Guachichiles and Zacatecos (2 of the 4 Indigenous groups recognized for the larger region at Contact time; see figure 2 in Mellink et al., 2018) in the “Guerra de los Chichimecas,” the costliest war that the Spaniards ever undertook in the Americas (Powell, 1977). This conflict lasted almost 50 years, because of the elusive nature of the Zacatecos and Guachichiles as well as of the habitat of the latter in that area: large forests of arborescent nopales (Mellink et al., 2018; Rivera Villanueva et al., 2019). These communities were so dense that fighting on horseback in them was not possible, preventing Spanish soldiers from retaliating the Guachichil attacks in their hit and run guerrilla warfare (Ahumada, 1566).

These forests, called tunales after the name “tuna” that is given to the fruits of nopales in Spanish, can be composed, at least nowadays, of up to 10 different morphospecies of nopal, although 5 arborescent species, which can reach several meters of height (Figure 1), dominate them: cardón, Opuntia streptacantha; apalillo, O. lasiacantha; duraznillo, O. leucotricha; cascarón, O. hyptiacantha; and chavena, O. chavena (MER-L, unpublished data), all of them endemic to Mexico (Bravo Hollis, 1978). Tunales are one type of a wider group of plant communities dominated by Opuntia spp. called “nopaleras” (Miranda and Hernández-X, 1963), “matorral crasicaule” (Rzedowski, 1965), and/or “cactus-acacia-grassland” (Gentry, 1957, after Shreve, 1942). The most extensive nopal communities covered large surfaces in the states of Aguascalientes, Zacatecas, San Luis Potosí, and Durango (Miranda and Hernández-X, 1963; Marroquín et al., 1964). However, the description provided by Gentry (1957) suggests that the Durango nopaleras were not of the dense arborescent type. In the southwestern part of the state of San Luis Potosí, nopaleras are found mostly on slopes, alluvial fans of rhyolitic and basaltic origin (both, extrusive igneous rocks), and sometimes on flat terrain adjacent to the former (Rzedowski, 1965).

Although nopales were the dominant plant form in tunales, as in the one that most impressed mid-16th-century Spaniards, these communities could include also shrubby and postrate nopales, as well as leguminous trees, especially mesquite (Prosopis spp.) in humid bottomlands, and huizache (Vachellia spp.) in the drier areas. Also included, although often overlooked, were yucca trees (Yucca spp.), as was documented in the 19th century between San Bartolo and the Hacienda de Jaral de Berrios (Berlandier and Chovell, 1850) and wild maguey (Agave salmiana subsp. crassispina, different from the central Mexico cultivated maguey, A. s. subsp. salmiana). Tunales shared the landscape with other plant communities, including those of magueyes and of yuccas, in addition to the more familiar looking, to Spaniards, grasslands, and oak (Quercus spp.) and pine (Pinus cembroides) stands.

Nopales have played a very important role in Mexican culture and for the survival of different nonagricultural human groups since pre-Hispanic times (Valdés et al., 2015), not only because of the pads and fruits themselves but also because of the wealth of other resources that some of the biological communities they formed provided, including, for example, agave, yucca fruits, several birds and their eggs, peccaries, and packrats (see comprehensive list in Mellink et al., 2018). Their importance was such that an Opuntia plant was part of the foundational myth of the Aztecs and, as such, became one of the 3 main components of the National Emblem of Mexico.

Notwithstanding the cultural importance of nopales and the communities they form since pre-Hispanic times (Sahagún, 1938, written in 1575–1577; Benavente, 1941), as well as their biological importance, they have been disparaged in modern times. Modern contempt for nopal communities is exemplified by 2 events. In 1979, Martín H. González-Alanís, the director of the range research department of the official Instituto Nacional de Investigaciones Pecuarias, instructed technicians under his supervision, EM among them, to evaluate the success of felling, followed by herbicide and diesel applications in removing arborescent nopales, within our study region. The argument behind this was that they had resulted from overgrazing and were “undesirable” (for livestock production). As another example, at an expert technical meeting on fruit-oriented orchards of cultivated nopales in which MER-L was a participant, in 2004, a nopal pest researcher with the Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias argued that communities of wild nopales close to such orchards should be removed because they were pest reservoirs.

Despite the preeminence of nopales in Mexican and regional identity and culture, the magnificent tunales of the southern part of the Mexican Plateau have been almost completely felled. Since the time of first contact between Guachichiles and Zacatecos and the invading Europeans, the landscape has become highly anthropized, with farmed patches, rangelands, and only small remnants of the pre-Contact vegetation (Riojas-López and Mellink, 2005). We concur with Rhemtulla and Mladenoff (2007) in that “…the past cannot be a blueprint for the future, [but] reconstructing these historical patterns and processes is key to understanding how present conditions came about, how ecosystems function, and in contributing to wise management and restoration decisions.” Reconstructing the history of landscape changes since Contact time is not without limitations for, as was found in Nevada, even in places where the arrival of Europeans was relatively recent (late 19th century) and descriptions of the original landscape abound, it is difficult to reconstruct the pre-Contact landscape (Gruell, 2012).

The case for the southern Mexican Plateau is more complicated than that of Nevada as Europeans arrived more than 3 centuries earlier and left few initial descriptions (see Mellink et al., 2018; Mellink and Riojas-López, 2020). Elías Amador (1906) was hampered in his effort to describe the physiography of the state of Zacatecas at Contact time by the lack of data and barely dared to say that the natural products of the landscape were the same as at his day (late 19th and early 20th century). Likewise, in 1997, Martín H. González Alanís, the same that had instructed removal experiments of arborescent nopales 2 decades earlier, claimed that there was no historical information to characterize the original vegetation of the region that we will cover. In contrast to Amador (1906) and González Alanís (1997) we are convinced that by gleaning, interpreting, and synthetizing the limited historical and geographical sources along with biological data and oral history on the region, it is possible to historicize landscape changes (sensu Beller et al., 2017) since the arrival of Spanish conquerors to the region. Here we focus on the magnificent tunales that used to cover large tracts of the region as a means to identify objectively biodiversity conservation needs, restoration efforts, and opportunities. In agreement with this general goal, our objective in this article is to historicize the fate of the magnificent tunales of the southern part of the Mexican Plateau.

Our study area is centered on the Llanos de Ojuelos, in the southern part of the Mexican Plateau, and approximately in the geographical center of the country. It extends eastward to the Valle de San Francisco and Valle de San Felipe, in the state of Guanajuato, and westwards to El Llano, in Aguascalientes (Figure 2). It is a tableland 1800–2500 m above sea level, with a basin and range topography (Nieto-Samaniego et al., 2005). Soils of the 4 eastern valleys are of Quaternary, alluvial origin; those in the westernmost valley, El Llano, originated from Miocene sandstones and polymictic conglomerates, while the mountain ranges are formed mostly by Oligocene rhyolites, rhyolitic tuffs, and ignimbrites (Servicio Geológico Mexicano, 1997; 1998). Soils are underlain by duripan (locally called “tepetate”).

The area is part of 3 hydrologic regions: Lerma-Santiago (Río Verde Grande basin), Salado (different drainages), and Pánuco (Río Tamuín basin). The existence of tepetate and the basin and range condition promote the existence of springs, small endorheic bodies of water, and seeps, especially during the rainy season. Currently, the water that drains often does not reach the lower parts of the valleys or the rivers as it is intercepted with dams, and earthen levees.

The climate is temperate semiarid, with rainfall being rarely abundant or regular. The annual precipitation is 400–700 mm, 80% of which falls between June and September, with no mid-summer drought. Pan evaporation exceeds precipitation in all months of the year. Mean annual temperature is 16°C–18°C, with a minimum in January (−2°C), and maximum in May (32°C). Frost can occur between November and April. Three climatic seasons can be defined: dry cold, dry warm, and rainy (see Mellink et al., 2016).

This region is part of Wagner’s (1964) “steppe, thicket & scrub desert.” Currently, the vegetation of the area is a mosaic of extensive, but overgrazed, grasslands (with grasses of the genera Bouteloua, Muhlenbergia, Eragrostis), xerophytic shrublands dominated by nopales (Opuntia robusta, O. joconostle, and O. leucotricha), and legume shrubs and trees (Vachellia spp., Mimosa spp.), with remnants of open forests of arborescent nopales (O. streptacantha, O. hyptiacantha, and O. leucotricha; Rzedowski, 2006). The mesas are occupied by grasslands, yucca communities (Y. decipiens and Y. filifera), and dwarf oaks (Quercus spp.), which occur also in ravines. The highest ranges have Mexican pinyons (P. cembroides). There has been no detailed inventory of the flora of Llanos de Ojuelos, but good approximations are found in Rzedowski and McVaugh (1966) and Harker et al. (2008).

We relied on 2 main documentary sources that provide information on habitats in the region at different periods. The first one was published literature, including formal books and journal articles, “gray” documents (publications with limited circulation, theses), and little-known works. These, we searched for in the library system of the Universidad de Guadalajara, the Biblioteca Pública del Estado de Jalisco “Juan José Arreola,” the University of California in San Diego, and regional libraries in Aguascalientes, Zacatecas, and San Luis Potosí, as well as the authors’ personal collections, internet databases, and scientific journals. The second source were unpublished documents guarded in the Archivo General de la Nación, México, the state historical archives of Jalisco, Aguascalientes, San Luis Potosí, and Zacatecas, the Biblioteca del Estado de Aguascalientes, the Archivo Diocesano del Arzobispado de Guadalajara, Special Collections of the University of California in San Diego, and the Archivo General de Indias, in Seville, Spain. We complemented this with the insight gained by us as a result of our research on wildlife ecology in the region in 1978–1981 and from 1995 to date, including events in which we directly participated. All locations mentioned in the text are indicated in Figure 3.

At the time of Spanish arrival to the southern part of the Mexican Plateau, tunales were extensive. Herrera y Tordesillas (1725) reported one between Zacatecas and the Chalchihuites mine as being over 50 leagues in length (240 km). Although this seems somewhat exaggerated as this length exceeds greatly the actual distance between these 2 locations, he was undoubtedly referring to a very large tunal. Likewise, around 1550 Fray Toribio de Benavente, better known as “Motolinía,” reported tunales in an area apparently between Jalostotitlán and Aguascalientes (Benavente, 1941; written in 1536). In 2 cases, tunales received specific names: Tunal Grande and Tunal Frontero (Ahumada, 1566). Based on the account of Ahumada (1566) and fieldwork specific for the purpose, we drew the approximate extension of these 2 tunales (Figure 4).

The “Mapa de las Villas de San Miguel y San Felipe de los Chichimecas y el pueblo de San Francisco Chamacuero” (elaborated in 1579 and Archived at the Real Academia de la Historia, Madrid; Figure 5), the oldest reference to the vegetation of the area, depicts the Valle de San Francisco as covered by a dense community of arborescent nopales, in which later accounts included mesquite (Berlandier and Chovell, 1850; Berlandier, 1980, based on his 1826–1834 reconnaissance) and, after their introduction by the Spaniards along the Camino Real de Tierra Adentro, pirules (Peruvian pepper trees; Schinus molle L.). These tunales were the habitat of the southern Guachichiles (Mellink et al., 2018) and were the stronghold for their resistance to the entrance of the Spaniards (Powell, 1977), largely because of the inability of the Spaniards to fight back on horseback in them (Ahumada, 1566).

West (1964), in apparent disbelief of the majestic nopal communities still present in the first half of the 20th century, indicated that “…the large stands of single desert species, such as the opuntia cactus, may have been due as much to human action as to edaphic conditions.” Similarly, Janzen (1986) contended that “[t]here is the strong possibility that some of the extensive nopaleras in the San Luis Potosi - Zacatecas region of the southern Chihuahuan desert are hardly more than the unkempt remnants of Indian orchards sustaining a large fauna of vertebrate pests.”

Two and a half centuries after the arrival of the Spaniards, tunales were still widespread and vigorous in and around the region, as reported for the Pinos area (Rendón, 1953), between this town and Ojuelos (Beltrami, 1830), between Lagos de Moreno and Encarnación de Díaz (Ruxton, 1848), and the area southwest of the city of San Luis Potosí (Peña, 1948). By mid-20th century, some tunales near settlements in San Luis Potosí had been totally cleared (Rzedowski, 1965). Bottomland mixed nopal-mesquite forests were present in Valle de San Francisco (Poinsett, 1825; Berlandier and Chovell, 1850; Berlandier, 1980), Ciénega de Mata, La Troje, Ledesma, El Puesto, La Punta, and San Francisco el Alto (Bárcena, 1888), and between San Bartolo and the Hacienda del Jaral de Berrios (Berlandier and Chovell, 1850).

In 1824, Giacomo Constantino Beltrami, traveling from Pinos to Ojuelos, indicated that he had journeyed “…travers l’empire des Opuntia …à travers toutes les espèces de Cactus …” (Beltrami, 1830) and, in 1827 Henry George Ward (1828) found that by La Tlachiquera (misspelled in the source), between Ocampo and San Felipe within the Tunal Grande area, the habitat was of loose stones and dense nopales, which impeded the lassoing of replacement mules, and that they had to make way for the cart by cutting nopales and shrubs. In 1846, the road from Lagos de Moreno to Encarnación de Díaz was devoid of trees but adorned with nopales and tunas (Ruxton, 1848).

In his report to Emperor Maximilian, Luis Robles Pezuela (1866), the Secretary of Development, wrote “…the one [fruit] that deserves more attention is the tuna called cardona, which is produced in great abundance in the departments of San Luis, Guanajuato, and Jalisco, because it forms a good part of the vegetal wealth of those regions and is called to figure as one of the most productive fruits” [our translation from Spanish]. Similarly, at the end of the 19th century “…in many parts [of Zacatecas] there are extensive mountains …” with more kinds of tunas than in any other state of the country, listing >50 types of tunas (Bonilla, 1889).

In 1930, there were still “…the typical endless nopaleras …” near the city of San Luis Potosí (Nieto in Márquez, 1986). In Pinos there were “…extensive magueyeras in which nopales sometimes grow in patches” (Rodríguez, 1946). Throughout southeastern Zacatecas, especially by the San Luis Potosí border, all terrain that was more or less flat and that had not been opened to farming was covered by “cardón-type” tunales. Lots within these tunales were assigned to the ejidatarios for the gathering of tunas for consumption or sale, and for the manufacture of queso de tuna (fruit paste of cardón tunas) and melcocha (jamed cardón tunas; no sugar added). In addition, they used the pads as fodder for cattle, while the fallen tunas were consumed by pigs and “beasts” of burden (horses, mules, asses; Peña, 1948). Queso de tuna and melcocha continue to be prized regional delicacies and obliged souvenirs to this date. A third product, colonche (alcoholic beverage produced by fermenting the juice of cardón tunas) is also a famed local product, but its shelf-life is only a few days and it grew very rare through the 21st century.

In 1959–1960 there were nopaleras with “…a large population and exuberance of plants …” especially at the boundaries of Zacatecas with San Luis Potosí and Aguascalientes (Claverán Alonso, 1961). Nopales cardón (perhaps including the closely resembling apalillo, cascarón, and/or chaveño), and duraznillo covered large areas on volcanic hills and even plains mostly from San Luis de la Paz, San Luis Potosí, to near Sombrerete, Zacatecas (Figure 6; González and Scheffey, 1964; Miranda and Hernández-X, 1964; Rzedowksi, 1964). Nopaleras occurred also in neighboring areas in the states of Guanajuato and Jalisco, but they were not included in the map describing the above. The densest area of nopales was west of San Luis Potosí, toward Pinos, with densities of up to 101–200 plants/ha of each of the 2 nopal species (Figure 6-left; González and Scheffey, 1964). Most of the areas covered by dense stands of arborescent nopales in the late 1950s have now been cleared (Figure 6-right). At present, arborescent nopaleras continue to disappear in the region (Figures 7 and 8). This felling of tunales has recently included the establishment of a photovoltaic power station (Figure 9).

Our study exemplifies how natural iconic communities once widely distributed can vanish almost inadvertently. Tunales in the region have disappeared extensively, but gradually. For example, the 2 tunales depicted in Figure 4 have been completely felled; while Figures 6–8 exhibit their disappearance during the last 60 years. Agriculture of the 17th to 19th centuries affected mostly those in humid bottomlands as the availability of water at these sites made them highly desirable for their conversion to agriculture, especially for wheat, but also for other crops such as corn (e.g., in Valle de San Francisco; Figure 4). In 1822, much of the bottomland mesquite-nopal-yucca stands between San Bartolo and Hacienda de Jaral de Berrios that had described before by Berlandier and Chovell (1850) had already been transformed into farmland (Poinsett, 1825).

According to the descriptions of Beltrami (1830), Ruxton (1848), and Ward (1828), the part of the Tunal Grande that was on hills and slopes escaped the initial transformation to cropland. So, at the beginning of the 19th century, the Hacienda de Jaral de Berrios complemented its income from the cultivation of corn and wheat in the bottomlands and the rising of livestock, with that from tunas and their derivates, including large quantities of colonche (Berlandier, 1980). This cropping of tunas required the existence of large tracts of tunal, which by that time occurred mostly on hills and slopes. At the end of the 19th century, tunas and their byproducts remained very important in the region (Robles Pezuela, 1866; Bonilla, 1889), reflecting the persistence of large tunales. Additionally, mesquite-nopal associations, sometimes with yuccas, were still found in Ciénega de Mata, Ledesma, La Troje, El Puesto, La Punta, and San Francisco el Alto in 1888 (Barcena, 1983).

The evidence available reveals that large tracts of arborescent nopal “forests” survived in the region well into the 19th and 20th centuries (Ward, 1828; Beltrami, 1830; Ruxton, 1848; Robles Pezuela, 1866; Rodríguez, 1946; Berlandier, 1980). Their persistence until right after the Mexican Revolution agrees with memories of going to a nearby large tunal to elaborate colonche, melcocha, and queso de tuna (María Ortíz, elder, Santa Rosa, Guanajuato, personal communication, 27/10/2016).

In the century after the Mexican Revolution ended (1921), the local population increased 6-fold (Figure 10), as per the national population censuses (available at the Instituto Nacional de Estadística y Geografía). This increase in peasant population led to the postrevolutionary agrarian land redistribution (specially in 1934–1940), and many hills and slopes that had been spared until then were plowed. So, although the destruction of tunales had been more frequent on moderately deep soils which were most useful for agriculture (Miranda and Hernández-X, 1964), eventually those that occurred on hillsides were also destroyed. Areas that were covered by arborescent nopaleras until then are evidenced by nopal-related place names, small patches of arborescent nopales, stumps of large nopales and, specially, by the memories of older inhabitants. An example of this occurs on the southeast slope of the San Pedro mountain range, that was part of the prehispanic Tunal Grande (Figure 4). Such land-use transformation may have been similar in other areas that had tunales, where peasants converted virgin lands to cultivation even if they were not very suitable for agriculture. This process of change from Tunal to cropland can be seen in the upper-right area of both images in Figure 11.

In the 1950s, smoke columns still spiraled everywhere in the area between El Rayo, Matancillas, and Ojo de Agua de la Palma during the tuna season as peasants prepared colonche, melcocha, and queso de tuna (Venustiano Castañeda, farmer, Ojo de Agua de la Palma, Jalisco, personal communication, 05/02/2008). During the 1960s–1970s, this landscape, seen from the Mesa del Sitio, “seemed to be ablaze” during nopal fruit season because of the insurmountable number of red tunas (Abel Martínez Gil, farmer, Ojo de Agua de la Palma, Jalisco, personal communication, 23/07/2008). In the late 1970s and into the late-1990s, some large tracts of tunales still persisted in the region (EM and MER-L, personal observation). Since then, they have been reduced drastically, and relicts are found mostly as scant, small patches (Figures 6–9).

As far back as written evidence exists, the tunas of nopal cardón have been preferred by humans over those of other nopal species (e.g., Robles Pezuela, 1866; Rzedowski, 1964), and the name Cardonas is a common place-name in the region (as in the lower part of Figure 11). In the mid-20th century when corn was in short supply, rural people were said to eat from several to many hundreds tunas cardonas per day, and Indigenous communities moved around following tuna ripening (Rzedowski, 1964). In 1950, tunas cropped from wild nopales for the market were estimated at 12,000 t in the state of San Luis Potosí and 3.5 t in that of Zacatecas, not including tunas cropped for self-consumption and for the fabrication of queso de tuna, melcocha, and colonche (Rzedowski, 1964).

The demise of tunales during the late 20th century is evidenced by comparing land use maps generated by the Secretaría de Agricultura y Recursos Hidráulicos (SARH; Ministry of Agriculture and Hydraulic Resources) in the late 1970s with the current state of the landscape. This transformation could have even been promoted by SARH itself through its 1972–1983 Programa Nacional de Desmontes (PRONADE; National Land Clearing Program) or through general policies to increase plowed surface and boost agricultural production.

As tempting as the suggestions of anthropogenic origin of tunales forwarded by West (1964) and Janzen (1986) might appear, there is no evidence to support them. West (1964) misconceived such large tunales as single-species communities when, in fact, they were composed of different, morphologically similar arborescent species. As for Janzen’s claim, part of it might have derived from the persistence of nopaleras despite the Late Pleistocene extinction of the megafaunal seed dispersers with which arborescent nopales very likely evolved (Janzen and Martin, 1982). However, he disregarded the dispersing role that medium and small animals, especially birds, some rodents, and ants, can play in their maintenance (see, e.g., Gonzalez-Espinoza and Quintana-Ascencio, 1986; Mellink and Riojas-López, 2002). Collard peccaries, Dicotyles tajacu (Linnaeus), white tailed deer, Odocoileus virginianus (Zimmerman), coyotes, Canis latrans Say, and gray foxes, Urocyon cinereargenteus (Screber) all disperse seeds after consuming fallen tunas, as commonly seen in the feces of the last 2 species (see also Mellink and Riojas-López, 2002).

Nevertheless, certain nopaleras might have been partially of anthropogenic origin. From about 200 C.E. to about 1100–1200 C.E., the area was occupied by a northward extension of Mesoamerica, which collapsed at the end of this period (Weigand, 1977; Elliot et al., 2010). The vestiges of Mesoamerican people in the region include unstudied archaeological terraces at Rancho Viejo, Chinampas, which are currently covered by 2 species of nopal (MER-L and EM, personal observation). These terraces might have been agricultural (sensu Fish et al., 1985; Nelson, 1992), rather than a pyramid as believed by local peasants. At La Quemada, some 120 km northwest of Rancho Viejo, plants cultivated on terraces probably included maguey (Nelson, 1992) in addition to maize and squash and, perhaps, nopal (Trombold and Israde-Alcantara, 2005). However, given the widespread abundance of nopal in our region, using valuable agricultural land to grow it would not make much sense. After the collapse of this Mesoamerican northern expanse, the area was reoccupied by hunter-gatherers (Kirchhoff, 1954; Powell, 1977; Elliot et al., 2010) or by semisedentary tunal inhabitants (Mellink et al., 2018) lacking, in either case, agriculture. Hence, the nopal community on the Rancho Viejo terraces more likely derived from defecation of the seeds of preferred tuna species by the Chichimeca later inhabitants, especially nopal cardón, one of the two species covering them.

One other anthropogenic nopalera, at La Providencia, Guanajuato, is of much recent origin. It is composed of only 2 species and has a fairly regular nopal distribution pattern. It was the product of intentional growing in the late 19th and early 20th centuries to improve the range for the raising of fighting bulls (Bruno Portugal, farmer, La Providencia, Guanajuato, personal communication, 07/07/2005). Likewise, nopal cardón in Villa de Arriaga grasslands has been argued to have been planted (Gómez González, 1963). We have not found further documentation of these 2 cases or of similar ones.

Five centuries ago the southern Guachichiles satisfied all their needs from tunales, namely, at least 10 plant species that provided food, alcoholic beverages, and hallucinogens, 7 birds (including their eggs), 6 mammals, 4 reptiles, grubs, and honey, in addition to at least 6 vertebrate species hunted at the tunal’s edges with grasslands and shrublands or in more open patches of tunal (Mellink et al., 2018). Now, of the majestic and imposing tunales of the region (Figures 1 and 5) only traces remain, and these, quite small, in a landscape matrix of agricultural parcels (Figures 6–8 and 11). Sadly, some of the most recent land from which tunal was removed has been seldom used to grow a crop, and has remained idle most years (e.g., that in Figure 7).

Although none of the plant species that were originally components of tunales seem to have become extinct, with the loss of this majestic habitat, the region has lost a unique, iconic plant community which harbored several plant species endemic to Mexico. The environmental services provided by the tunales have not been fully recognized and have been underestimated. These services included plant and animal resources, conservation of biodiversity, soil formation and erosion prevention, water retention, and carbon sequestration. Moreover, tunales were an important biocultural element that provided a sense of belonging and pride for the region’s inhabitants, but the current human generation has been deprived of that cultural anchoring.

As the comparison of the area northwest of Ledesma exhibits, abandoned cropland can over time grow new communities of arborescent nopales (Figure 11). In some areas, tunal could develop from small remaining patches. In other, however, it might require active establishment and management. Arborescent nopales are hardy species, but to avoid the complete disappearance of the tunales, their ecological and biocultural importance and significance must be revaluated, and strong lobbying efforts and management actions developed.

Notwithstanding the disappearance of the large tunales, and despite decades of neglect, the cultural association with tunas has not faltered, and queso de tuna and melcocha have never ceased to be produced. Optimism is raised by the fact that although still extremely low-scale and local, the use of colonche is beginning to revive in the Tunal Grande region, with an annual “Feria del Colonche” having been organized since 2015 in Laguna de Guadalupe. The interest for these products by themselves will not bring tunales back into the future, but they can stimulate or help in forwarding restoration and conservation demands for this mighty habitat.

The destruction of the tunales occurred in 3 major phases: (1) tunales in humid bottomlands begun to be felled in the 17th century, to allow cultivation, especially of wheat; (2) tunales on dry habitats and slopes were cleared after the agrarian reform that followed the Mexican Revolution in the early 20th century; and (3) most of the last remaining tunales succumbed to a drive of agricultural expansion in the late 20th and early 21st centuries.

With the vanishing of the majestic tunales, the region has lost a very important biocultural element that provided a sense of belonging and pride for the region’s inhabitants and provided several ecosystem services. Arborescent nopales are hardy species, but to avoid the complete disappearance of the tunales, their ecological and biocultural importance and significance must be revaluated, and strong lobbying efforts and management actions developed.

This article is based on analysis of published and archival information and no data sets were generated.

We dedicate this article, with great respect, to Eulogio Pimienta-Barrios. We thank the staff of the following archives (particular staff members who were especially helpful): Archivo General de la Nación, the state historical archives of the states of Aguascalientes, San Luis Potosí, and Zacatecas, the Biblioteca del Estado de Aguascalientes (Martín Oliva), the Archivo Diocesano del Arzobispado de Guadalajara (Sister María de Teresa), Special Collections at the University of California at San Diego, and the Archivo General de Indias, in Sevilla (Antonio Sánchez de Mora). The following colleagues provided important logistical support or information: Jaime Luévano (Centro de Investigación Científica y de Educación Superior de Ensenada, B.C.; CICESE), José Antonio Rivera (Colegio de San Luis), Faustino Moreno Ceja and Diana Anabel Sánchez García (CUCBA, Universidad de Guadalajara), María Elena Siqueiros (Universidad Autónoma de Aguascalientes), Martín Escobedo (Universidad Autónoma de Zacatecas), Celina Becerra (CUCSH, Universidad de Guadalajara), Celina Solís Becerra (University of Vancouver), Antonio Gómez (consultant), Pedro Arturo Martínez Hernández (Departamento de Zootecnia, Universidad Autónoma Chapingo), and Salvador Arias (Universidad Nacional Autónoma de México). Many persons in the Llanos de Ojuelos who provided us information, valuable insights, permission to work in their properties, and logistical support: Armando Esparza, Santoyo family, Melquiades Contreras, Gilberto Cardona, Margarita Chávez, and Ezequiel Martínez. Drs Exequiel Ezcurra and Suzanne Fish kindly assisted during the editorial process. We extend our deepest appreciation to all of them.

Funds for this project were provided by Mexico’s Consejo Nacional de Ciencia y Tecnología (CONACYT, CB-2010-01-157186), Universidad de Guadalajara, CICESE, and personal resources from the authors. We wrote the first version of this article while MER-L was on sabbatical stay at the Laboratoire Chrono-environnement, University of Burgundy - Franche-Comté, and EM was on a sabbatical stay at the Institut Universitaire de France, in Besançon, both with support from CONACYT.

The authors declare that they do not have any competing interests.

Contributed to conceptualization of research and manuscript, literature and archival review, interpretation, writing, approval of final version: MER-L, EM.

How to cite this article: Riojas-López, ME, Mellink, E. 2023. Vanishing of the mighty tunales of central Mexico: A 5-century history of landscape change. Elementa: Science of the Anthropocene 11(1). DOI: https://doi.org/10.1525/elementa.2022.00114

Domain Editor-in-Chief: Steven Allison, University of California, Irvine, CA, USA

Associate Editor: Danielle Ignace, Smith College, Northampton, MA, USA

Knowledge Domain: Ecology and Earth Systems