Materials and methods

Study site. Zumpahuacán is in the southern portion of Mexico, between 18° 50’ 11’’ N and 99° 34’ 43’’ W, ranging from 1,000 to 2,600 m asl (^{Estado de México 2023}). It is bounded on the south by the states of Morelos and Guerrero, on the north by the municipality of Tenancingo, on the east by Malinalco, and the west by Guerrero. From a biographic and floristic perspective, it is an interesting zone since it is located at the intersection between the Holarctic and Neotropical regions, and it is part of the biogeographic province known as Sierras y Valles Guerrerenses de la Cuenca del Balsas (^{INEGI 2023}) (Figure 1). It has been designated as a Natural Protected Area, along with Malinalco and Tenancingo (Parque Ecológico y Recreativo de Tenancingo-Malinalco-Zumpahuacán) by the Mexican government since 1981 (^{Gobierno del Estado de México 2023}).

Figure 1 Study site. 

This municipality is dominated by tropical and subtropical vegetation, including pine forest, oak forest, tropical semi-evergreen forest, gallery forest, and tropical deciduous forest (^{López-Patiño et al. 2012}), which cover most of the municipality's land area (^{Casanova 1999}). The typical climate is template, subhumid, with less than 5 % winter precipitation. The average annual temperature is 14 °C, and the average annual rainfall is 651.1 mm (^{López-Patiño et al. 2012}). Zumpahuacán's dominant topography is Karstic, with smooth hills of Cretacic-Jurassic sedimentary rocks (^{INEGI 2010}, Cretaceous Formations of Central America and Mexico) (Figure 2). Zumpahuacán has one of the most extensive areas of Leptosols, which are exploited to extract quarry and other minerals (^{Sotelo-Ruíz et al. 2020}).

Figure 2 Typical karstic landscape of Zumpahuacán, Estado de Mexico: a) Smooth hills with tropical dry forest; b) Cretacic-Jurassic sedimentary rocks; c) milpa growing between sedimentary rocks. 

Zumpahuacán is home to 18,833 people, most of them mestizos, who live in 15 small communities known as delegaciones (^{Gobierno del Estado de México 2004}), and it is classified as one of the twelve poorest municipalities in Mexico (^{Gobierno de México 2022}). Agricultural and cattle activities are developed in this Karstic landscape (Figure 2A-C). They cultivate maize, beans, squash, and watermelon for subsistence. However, many plant products are gathered from wild like Aristolochia orbicularis Duch., tlacopa; Asclepias linaria Cav., soldadillo/siete negritos; Cosmos sulphureus Cav., chuchupal/mozote; Dalea foliolosa (Aiton) Barneby, escoba; Dalea leporina (Aiton) Bullock, escoba; Erigeron karvinskianus DC., escoba; Schkuhria pinnata (Lam.) Kuntze, escoba anis; Tagetes micrantha Cav., escoba. Others are tolerated like Porophyllum calcicola B.L. Rob. & Greenm., pápalo de monte; Porophyllum ruderale var. macrocephalum (DC.) Cronquist, pápalo, and many are protected species, like Leucaena leucocephala (Lam.) de Wit, guaje; Spondias purpurea L., ciruelo. All these mentioned species are part of the hundreds of species from the tropical dry forest and semideciduous forests that satisfy families’ necessities, and they are also sold in regional markets of the Estado de Mexico (Chalma, Malinalco, Tenancingo, Tenango) or some municipalities of the state of Morelos.

This town was part of the Matlatzinca culture's nuclear zone until the Aztec Empire in 1428 (^{Velasco-Godoy 2003}, ^{Garza-Merodio & Fernandez-Christlieb 2016}) and played a major role in trade operations between the shore and the Aztec-dominated central region. However, acculturation processes eradicated both languages, and now no one speaks or understands Náhuatl or Matlatzinca. Despite this, Náhuatl words can be found in the names of flora, animals, and local landmarks (parajes). Its name is a toponym derived from zompantli, meaning "place with skull hangers" (^{Velasco-Godoy 2003}).

Collaborator selection and interviews. To comprehend tezcalera management, we used ^{Hernández-X.'s (1988)} three axes for studying TAE: ecological, technological, and socioeconomic.

In 2020, we started ethnobotanical studies with students of the Universidad Autónoma Metropolitana in seven communities of this municipality, including the municipal seat. During these studies, we became interested in tezcaleras. Derived from our field experience, in 2021, we decided to work in four to study tezcaleras: Ahuatzingo, San Pedro Guadalupe, Santa Ana Despoblado, and Santa Cruz Atempa (Figure 1). All of them are small communities with a population of less than 400 people, whose principal activity is agriculture.

Before the fieldwork, we contacted the Delegados, the local authorities in these communities, and told them about our interest in studying tezcaleras (^{Albuquerque 2014a}). Following that, we carried out tours inside the communities and spoke with the residents to see if they were interested in joining our project. It is important to mention that this study was developed during the COVID-19 pandemic, and people feared infections. We followed local restrictions throughout the project and were careful to obtain permission before visiting locations or fields to collect and photograph landscapes, plants, and people. The participants were picked according to their availability.

Semi-structured interviews were conducted with six campesinos from each community (total N = 24) to learn about agricultural practices and tools used in tezcalera management, as well as their knowledge of floristic aspects related to wild and agrestal plants growing inside the plots (^{Alexiades 1996}, ^{Albuquerque 2014b}). Following the guided tour method, we also visited the plots to observe and document agricultural practices, take photographs, and interact with the laborers whom the landowner hires to do some work (^{Albuquerque 2014b}).

Campesinos stated several terms during the interviews: roze and quema, tlacolol, milsol, and barbecho. We learned from campesinos’ descriptions and field trips that these terms were linked to temporal/spatial changes of the tezcalera, and we observed variations in floristic composition. Based on this information, we chose seven tezcaleras with different management histories to describe these possible changes in floristic composition based on the kind of crop, fallow period, time with this management, and times of agrochemicals application during one year (Table 1): one tezcalera in the fallow process for six years (tezfa); two tlacololes coming from fallows of dry deciduous forest with different fallow times, and opened the year of the study to cultivate them with milpa (maize) and other crop species (tla15 y tla40); one milsol, which is a tezcalera cultivated with maize for eight consecutive years (milma); two tezcaleras cultivated with Agave angustifolia, also with different years of cultivation (milaga4, milaga2); one tezcalera used for foraging (potrero) (Figure 3); in this case, potreros correspond to milsoles that are destinated to foraging for some years, and then they go into fallow, thus beginning a regeneration process of the tropical dry forest.

Figure 3 Tezcalera plots with different management history: a) tezcalera in the fallow process for six years (tezfa); b) tlacolol coming from fallow period of 15 years (tla15) and cultivate with milpa (maize) and other crop species; c) tlacolol coming from fallow period of 40 years (tla40) and cultivate with milpa (maize) and other crop species; d) milsol cultivated with maize for eight consecutive years (milma); e) tezcalera with Agave angustifolia cultivation for four years (milaga4); f) tezcalera with Agave angustifolia cultivation for two years (milaga2); g) tezcalera used for foraging (potrero). 

To analyze the possible relationship between agricultural practices and the richness, composition, and abundance of native wild and agrestal germplasm growing in this ancestral TAE, a structured interview was applied to the plots’ owners to get specific information about the crops grown, the agricultural practices employed, the tools used, and the dates, names, and amounts of inputs used.

Rather than recording the surrounding vegetation, we recorded the wild and agrestal weed species that thrive within each plot. We followed the "W" method (^{Caamal & Castillo 2011}), which entailed drawing an imaginary diagonal line within each plot and collocating 50 × 50 cm squares every 20 meters, following the silhouette of an imaginary letter W. In each square, the abundance of each morphospecies was registered. To compare with the floristic components of tropical dry forest, we collected voucher specimens from different areas of post-milpa fallows, many surrounding active milpas (Figure 4).

Figure 4 Sampling stages in the different tezcaleras: a) inside each plot, several 50 × 50 cm squares were collocated; b) inside each square, the different weeds were recorded, with their respective abundance; c) voucher specimens were obtained from each plot. 

Two or three voucher specimens of each morphospecies were collected, pressed, and dried according to standard methods (^{Lot & Chiang 1986}). Specimens were identified, and scientific names were adjusted to the International Plant Names Index (^{INPI 2024}).

Data analysis. Interview responses about agricultural practices were analyzed with descriptive statistics. Their descriptions were used to visually represent the management of tezcalera, including dates and tools.

To compare possible differences in agricultural practices between plots with different management histories, information from the plots’ owners was also transformed in numbers to elaborate two values:

The intensity of management value was calculated as the sum of land management and technology level values. Values near zero suggest low-intensity management; high values imply high-intensity management (Table 1). These values were correlated with floristic information.

We constructed an Excel database based on floristic sampling to calculate the relative abundance (RA) and relative frequency (RF) of morphospecies using the following formulas:

With these data, the importance value (IV) of each weed was obtained as follows:

Because the basal area or plant cover was not included, this IV differed from that provided for studies on the relative ecological importance of different species in plant communities (^{Mueller-Dombois & Ellenberg 1974}). Each species may have a maximum value of 2. Values close to 2 suggest that certain species have become dominant. According to ^{Moreno (2001)} and ^{Baselga & Gómez-Rodríguez (2019)}, we evaluated specific richness using richness and abundance data. We also counted the number of herbs, shrubs, and trees (^{POWO 2024}) in each plot, as well as the number of native/exotic species (^{POWO 2024}) and their risk status (^{POWO 2024}).

To evaluate possible relationships between tezcaleras according to their plant composition, we elaborated a database with the absence-presence of species, and we applied a PCoA analysis using PAST 4.

Results

Ecological, technological, and socioeconomic characteristics of tezcaleras. Tezcaleras are TAE found in cretaceous rocks, some more than one meter tall, with rough, often angled surfaces. A thin, sometimes deep, soil layer, as well as humidity, captures between. Campesinos sow seeds of crop species such as maize (Zea mays L.), beans (Phaseolus vulgaris L.), squashes and pumpkins (Cucurbita moschata Duchesne, C. pepo L.), chilacayote (C. ficifolia Bouché), watermelon (Citrullus lanatus (Thunb.) Mansf.), bule (Lagenaria siceraria (Molina) Standl.); maguey (Agave angustifolia Haw.) production has recently displaced conventional crops. Some campesinos promote edible weeds known as "quelites" in some instances. Tezcaleras, according to campesinos, have a cyclic process with multiple stages that begin in tropical dry forests or tiny patches of oak forest (Figure 5). The following are the names and processes involved:

Figure 5 Tezcalera cycle: a) primary vegetation, tropical dry forest; b) roze-quema (slash and burn) where a small plot is cleaned; c) tlacolol: first year of sowing; d) milsol, from the second or more years of continuos cultivation; e) potrero, destinated for foraging. It comes from tlacolol or milsol. New crop, Agave angustifolia. It comes from tlacolol, milsol, or even potrero. The destiny of this kind of tezcalera management is unknown. Pink lines indicate the forward process from tropical dry forest to the traditional milpa system (monoculture or polyculture); blue lines indicate foraging use (potrero) of tlacolol or milsol. It can last only a few months or years; lilac lines indicate the reverse to the fallow process; black lines indicate changes to an intensive permanent crop, Agave angustifolia. 

Roze-quema.- To clean a plot of forest, mature trees are cut with an ax, cutlass, or electric saw, leaving the base of the trees of different perennial species such as palma (Brahea dulcis (Kunth) Mart.), different species of copales or cuajiotes (Bursera spp.), guaje (Leucaena macrophylla Benth), and cacaloxochitl (Plumeria rubra L.), among others, to allow for further regeneration. The shrubs and herbs are then cut down using a cutlass (Figure 6A, B). All the material is gathered and burned in heaps (rejuntar) throughout the plot (Figure 6C, D). To contain the fire, campesinos clean a 1 m wide line around the plot (guardarraya). The hash is collected and distributed throughout the plot. Campesinos believe that hash fertilizes the soil and kills nixcuitl (bug larvae). This must be done before planting during the dry season.

Figure 6 Agricultural activities followed in tezcalera: a) a fallow plot of tropical dry forest, before slash and burn; b) big trees are cut and left in the plot; shrubs and herbs are then cut down using a cutlass; c) All the material is gathered and burned in heaps (rejuntar); d) weeding with herbicides before sowing; e) Seeds are ready for sowing. Campesinos use bules, morrales, nylon, or buckets. f) Sowing with azadón; g) tools used during sowing: azadón, palo de siembra, barreta or chuzo; g) tools used during harvest: pizcalón, and ayate; h) the maize stems (aguasol) are gathered and burned in milsoles, after harvest. In many cases, campesinos use aguasol to elaborate fences. 

Tlacolol.- After cleaning the plot, campesinos begin cultivating it at the start of the wet season, between May and July. Tlacolol involves two types of management: a) traditional management, which is manual labor, and occurs when campesinos have time for agricultural labor or when milpa (maize) is growing together with other crops like beans (Phaseolus), chilacayote (Cucurbita ficifolia), pipián (C. argyrosperma C. Huber), squash (C. pepo), pumpkin (C. moschata). Campesinos also gather some quelites like different kind of pápalos (Porophyllum ruderale (Jacq.) Cass., P. warnockii R.R. Jhonson), chichihuanche (Euphorbia eglandulosa V.W. Steinm.). To store the seeds and transport them while sowing, they use bules (natural containers elaborated from Lagenaria siceraria fruits), or morrales elaborated with palm leaves (Brahea dulcis), or nylon. During sowing (Figure 6E, F), they sow 4 or 5 seeds in those areas where they consider there is enough soil. To do this, they use palo de siembra (a thin piece of trunk or branch whose point is sharpened with the cutlass), barreta, azadón or chuzo (a thin piece of trunk; in one side, a relatively sharpened piece of iron blade is inserted) (Figure 6G), to make a small hole and incorporate the seeds, then cover them with a small amount of soil that is pushed with the feet. They mention that soil fertility is adequate in this kind of plots, so they do not apply fertilizers or agrochemicals. Two or three weddings are done with cutlass and azadón, depending on the rainy season; they are necessary before ears are ready for eating as elotes, and before the harvest of mature ears (mazorca), at the end of the season. For ear harvest, they use pizcalón, a thin metal rod introduced in the basal area of the leaves that involve the ear; they cut the external leaves and pull the ears. Elotes or mazorcas are kept in ayates (Figure 6H). b) technician management occurs when campesinos apply agrochemicals such as fertilizers, pesticides, and herbicides. This management occurs when campesinos cultivate milpa and wish to "ensure" their yield. Even though the tlacolol soil includes many natural nutrients and some biological interactions, they opt to use them. Herbicides used for weeding include Amina 4, Diablo, Secafin, red-capped Faena, green-capped Faena, and Paraquat. Campesinos dilute 30 ml/ 10 lt of water and sprinkle it with a spray pump before sowing, between May and June, at the start of the rainy season. Because perennial weeds, such as climbs, develop quicker than crops, some apply a second spray one month after sowing. Chemical fertilizer is also used, most typically urea, sulfate, or a combination of both. They are added only once, after the rainy season has begun, to aid in the assimilation of fertilizer into the soil and its absorption by the plants (Figure 7 A, B).

Figure 7 Weeding practice within tezcaleras: a) pump to spray herbicides; b) some of the commercial herbicides. 

Milsol.- From the second year until the areas fallow again after several years of continuous cultivation, plots are known as milsol. As a result, milsoles of varying ages exist: two years, or ten years. According to the campesinos, the oldest is roughly 20 years old. Milsol plots are cultivated with conventional annual crops, although campesinos have lately added Agave angustifolia, which is changing traditional methods, particularly the time set aside for fallow.

The milsol stage is extremely vulnerable to fertilizers and agrochemicals. Campesinos believe that because soil becomes exhausted and production decreases year after year, they must add chemical fertilizer, which is applied twice or three times during crop growth. Herbicides are also applied twice, three times, or more times. Weeds have no cultural significance in this scenario; they are just named jehuite and eradicated.

Pests such as gusano cogollero (Spodoptera frugiperda (J.E. Smith), Noctuidae), picudo (Curculionidae), and isticuil (Scarabaeidae) are common in these plots. Campesinos use a spray pump to apply Monitor, Malation, or Foley when pests appear. Campesinos stated that they began using these products about 30 years ago. Before it, all practices were carried out completely using human labor and traditional tools. Campesinos mentioned that pests were uncommon. The only problem was gusano cogollero, which used to be controlled with ash.

Barbecho is another farming technique in Zumpahuacán. Because barbecho is performed in even plots with a deeper layer of soil, fallow is relatively brief, lasting just a few months, and maybe plowed with a yunta or tractor (Figure 8 A, B), Zumpahuacán campesinos clearly distinguished it from Tezcaleras. All of them stated that the barbechos that are currently being worked on have always existed, and it is likely that they were also opened from the forest, but they did not see this activity. Occasionally, campesinos move small and loose rocks on one of the borders of the tezcalera to facilitate labor inside the plot. These rocks are collocated on one of the borders like a fence, whose local name is retajo (Figure 8 B).

Figure 8 Variations in landscape management: a) Barbecho, which is used for intensive agriculture; b) Retajo, which is a small fence constructed with small, loose rocks. 

Agricultural activities, in general, rest on traditional socioeconomic and cultural elements that reinforce the characterization of tezcaleras as a traditional agriculture system. As it can be perceived, almost all these activities, except for pesticide application, rely on human labor, which is carried out with familiar labor because hiring laborers is expensive. It is increasingly difficult to find people. They hire laborers for most of the practices, whose numbers vary depending on the type of labor (Table 2).

They also follow some traditional ceremonies completely related to agriculture. Campesinos and their families perform a misa (Catholic ceremony in the temple) on May 15th, corresponding to San Isidro Labrador. The priest blesses the seeds that will be sown and the tools and beasts they will use for agricultural tasks.

The 28th of September corresponds to San Lorenzo. Winds are particularly frequent throughout this month, and it is normal for them to blow down the milpas. Campesinos place pericón crosses (Tagetes lucida Cav.) in the four corners to ward off envy or the devil, who is responsible for throwing them away.

Starting in November, when harvesting season begins, campesinos who are harvesting shoot off fireworks to warn others (Table 2).

Changes in wild and agrestal richness and composition in tezcaleras with different management histories. The results of floristic sampling of tezcaleras with different management provide vital information regarding the effect of cyclic management on wild and agrestal weed richness and composition, as well as their conservation. We collected 161 morphospecies from 45 botanical families, of which 118 were identified to species level, 16 to genera, and seven to family; 27 were still unidentified. Related to their biological form, 51 are woody species (more than 30 %), from which 21 species are trees, 18 are vines, and 12 are shrubs; 82 are annual, perennial, or arborescent herbs, and one parasitic (Table S1). The most common families were Asteraceae, Fabaceae, Poaceae, Euphorbiaceae, and Malvaceae. The rest of the families were represented by five (Solanaceae), or fewer species.

There were just three exotic species: Chenopodium aff. album L, Cyclanthera dissecta (Torr. & A. Gray) Arn., and Sida abutilifolia Mill. Some have restricted distribution and are endemic to the Balsas region, like Bursera hintonii Bullock, Cordia morelosana Standl., Lippia bicolor Kunth & C.D. Bouché, Marina greenmaniana (Rose) Barneby, Porophyllum calcicola. Thirty-four species were classified as endangered or vulnerable: 29 as least concern, three as vulnerable, and one as nearly endangered (Table S1). A comparison of floristic composition in tezcalera plots with different management history, fallow periods, and agricultural practices reveals significant differences:

The tezcalera under fallow for 5-6 years (tezfa) presented a floristic composition mostly of annual species, as well as some representative shrub and tree species of tropical dry forest: Brahea dulcis, Croton ciliatoglandulifer Ortega, Vachellia pennatula (Schltdl. & Cham.) Seigler & Ebinger., Lysiloma acapulcense (Kunth) Benth., and Acacia cochliacantha Humb. & Bonpl. ex Willd., which suggests that they are some of the pioneer species that begin the succession process (Table 3).

Both tlacolol plots (tla15 y tla40) were destined for milpa cultivation, mixed with other annual crops like squash and beans. Both plots had similar Levels of Technification and Management Intensity values. Both exhibited h the lowest abundance and the highest specific richness values. They also have common woody and vine species, all of them because of regrowth after slash.

In the case of milsoles (milma, milaga4, milaga2), Land Management and Level of Technification values are higher than those of tlacololes. They tend to exhibit lower species, family richness, and specific richness but higher abundance values, and they contain smaller vine species than tlacololes.

The plot destined for foraging (potrero) had the lowest floristic richness scores. Even though the owner considered it an abandoned plot and exhibited the lowest intensity of management values, it has been utilized as pasture for ten years. Thus, the floristic composition has diminished; most species are annual weeds. Despite these differences in richness and abundance, the PCoA based on presence-absence did not exhibit groups between tezcaleras, suggesting that plant composition is similar (Figure 9).

Figure 9 Cluster Analysis based on absence-presence of wild and agrestal species in seven tezcalera plots: tezcalera under fallow process for 5-6 years (tezfa); tlacolol plots (tla15 y tla40); milsoles (milma, milaga4, milaga2); plot destinated for foraging (potrero). 

From the 164 morphospecies, 114 had an intangible or tangible value for Campesinos: 28 are recognized by morpho-physiological attributes (flower color, leaves, and texture) and include regrowth of trees and shrubs, as well as annual weeds; 44 are recognized by their medicinal benefits; 37 species are food plants, including leaves, fruits, or seeds; and ten species are used to elaborate different handcrafts (Table S1). Comparisons between tezcaleras with different management indicated that there were recognizable or useful species; however, in potrero and Agave1 the number of edible plants was lower.

Discussion

Tezcalera is a traditional agroecosystem (TAS), as defined by ^{Dell (1953}), ^{Cruz-León (2003)}, and ^{Pérez-Sánchez et al. (2014)}: it develops in response to environmental factors such as physiography, soil, and water availability, technological level, and function based on human labor. It is also a relic of one of Mesoamerica's most ancient agricultural systems, based on slash-and-burn (^{Cook 1919}, ^{Flannery et al. 1967}). According to local campesinos, in the tezcalera, there are various stages of the same agricultural system, beginning with the cleaning of tropical dry forest plots, where tlacolol corresponds to the first-year cultivation. From the second to subsequent years, tlacololes are named milsol, traditionally cultivated for various years and then abandoned to fallow for other years. This notion of a cyclic process in tezcalera has been fundamental to preserving the entire ecosystem, including many floristic elements that are representative of the Balsas floristic region. Campesinos understand that the fallow process will ensure soil recovery and the possibility of sown in this place someday, some years later. These findings are analogous to those reported by ^{Pérez-García & del Castillo (2017)} in Oaxaca. As we mentioned before, barbecho is an intensive agricultural system that differs in management. Thus, floristic composition and structure have become very simplistic. In the case of Agave monoculture, this is also happening.

In this cycle process, maize or milpa is the essential component, which can be cultivated alone or accompanied by other crops. This process is very similar to those descriptions made a century ago. ^{Cook (1919)} and ^{Diehl (1969}) described milpa as "the raising of corn on clearings in tropical forest areas, and these plots are abandoned after two or three crops, or possibly more, depending on the characteristics of the specific plot, the amount of time it has rested since last used, and the work habits of the individual farmer."

During literature revision, we found variations in the terms used in Zumpahuacán. For example, ^{Dell (1953)} referred to milpa and tlacolol as distinct systems closely linked in the processes involved. Many scholars have regarded milpa as an obliged polyculture system based on maize, beans, and squash since the 1960s. This concept was supported by ^{Grigg (1974)}. For the inhabitants of Zumpahuacán, milpa is just maize, growing alone or accompanied by other crop species.

Some authors considered the concepts tlacolol and barbecho to be synonyms ^{Flannery et al. (1967) Moreno-Calles et al. (2013)}; others, such as ^{Lees (1971)}, consider the whole cycle process (from slash and burn to fallow) and barbecho to be synonyms: "a system of "barbecho" is practiced: the natural vegetation is cut down with cutlass´s, horned on the field, the field is plowed and planted for perhaps three to five years, then left fallow for about the same amount of time, and the cycle is repeated again."

According to ^{Barrett (1970)}, slash and burn vary from barbecho due to the length of the fallow: “The methods used to raise these crops were several. Palerm describes three general systems as being widespread in Mesoamerica: slash and burn (roza), fallow (barbecho), and irrigation (regadío), The roza system, with its long-term forest fallow, was largely restricted to humid tropical areas, but a combination of irrigation and short-term fallow, or barbecho, was undoubtedly practiced in the Tepalcatepec lowland.” Zumpahuacán collaborators distinguished slash and burn from barbecho; thus, their conception is more like ^{Grigg (1974)} description: “In the uplands of the Mesa Central, and particularly on the steeper slopes, is found the barbecho system. There is some soil preparation after burning, and the fallow period rarely exceeds the period under crops, so the natural vegetation is not allowed to regenerate.”

The socioeconomic dynamics involved in tezcalera management add elements that characterize it as a TAS: most of the activities and the tools employed during them are sustained by human energy. ^{Cook (1919)} stated in the instance of milpa: “...since only a minimum of labor and equipment is required. The ax, or the cutlass, is the only necessary tool. Tribes who did not have effective cutting implements felled or girdled the trees by building fires around them.” He also described different aspects of milpa agriculture based on the family’s labor. As we described in the results, this pattern was found again 100 years later in tezcaleras. The prevalence of this TAS exhibits a real adaptation to socio-environmental conditions.

Cultural practices are the third component to characterize this TAS: those ceremonies followed at different moments of the agricultural cycle of milpa have been documented very early in colonial literature (^{Acuña 1986}, ^{Sierra-Carrillo 2007}). They are clearly part of the Mesoamerican cosmovision, adapted during the colonial epoque, and at present generate links between different communities, enhancing the identity of their inhabitants. Because they are related to seed and land “protection” through religious practices, Campesinos ensure not only useful products (corn, beans, quelites), but also the maintenance of the ecosystem.

Floristic composition in tezcaleras with a different management history. Tezcaleras in Zumpahuacán are important habitats for native and endemic tropical species. As previously stated, a relevant characteristic of this TAS is that practically all the wild and agrestal species that are growing in the tezcaleras are native, which is a remarkable finding given that at least 40% of the species in previous research in other agroecosystems were exotic (^{Vieyra-Odilón & Vibrans 2001}, ^{Rendón-Aguilar et al. 2021}, ^{Rivera-Ramírez et al. 2021}). These findings support the notion that many native weeds are adapted to milpa traditional management due to life-history characteristics that allow them to resist the presence and displacement of exotic weeds (^{Molina-Freaner et al. 2008}). In this case, the very rocky topography and significant seasonality could favor the presence of native species despite the extensive use of herbicides.

Another feature of this TAS is the presence of 35 species classified in one of the risk categories, which is a high value compared to previous publications. We found twelve species endemics to the Balsas region or southern Mexico, without information on their risk status. This study provides a window into these species' ecological and biogeographical characteristics, which are much more interesting when they are part of the dynamic of agricultural management. A comparison of plots with different management histories gives evidence of the ecological influence of management intensity on floristic composition and native germplasm conservation. Tlacolol had more species and families and a greater specific richness. A similar pattern was found in one of the Agave plots (milaga 2), which had a comparable Intensity of Management value. Because intense Agave cultivation is new (less than seven years), it will be interesting to see how it affects floristic richness and composition. Potrero represents another management history, where intense management may drastically diminish the floristic richness and affect the composition. Intensity of Management is the sum of different components. However, previous studies have suggested that herbicides seem to influence the species richness, as well as the relative abundance of some species (^{Rivera-Ramírez et al. 2021}, ^{Rendón-Aguilar et al. 2021}). This pattern was observed in milsoles, where weeding control with herbicides is frequent. These issues have been discussed with campesinos, who are clear that weed richness and abundance have changed and decreased. However, they argue that weed management is faster, and they don't have time to manually clean their plots. It is necessary to evaluate more plots to have comparably more data and to understand the dynamic of this kind of management, including herbicides and chemical fertilizers on floristic richness and composition, as ^{Velasco-Murguía et al. (2021)} suggested.

Floristic composition is primarily composed of native species. An important proportion corresponds to woody species and vines, which are representative of the tropical dry forest. The presence of tocones is important to the faster recovery of vegetation during fallow periods (^{Pérez-García & del Castillo 2016}, ²⁰¹⁷). The presence of surrounding areas with different fallow times is necessary to allow rapid recovery of milsoles and potreros, to maintain carbon reservoirs, to maintain wild and weed native germplasm, and to the resilience of this important area of tropical dry forest within the biographic province of Cuenca del Balsas (^{Velasco-Murguía et al. (2021)}.

We conclude that tezcalera is a biocultural unit, clearly differentiated from others, based on ecological, technological, and cultural elements that characterize it. Because of the intrinsic nature of tezcalera, most ancient traditional practices have survived and have had a positive impact, not only on the floristic richness and composition of native weeds but also on the entire ecosystem. This TAE has allowed the coexistence of domesticated, tolerated, and wild elements, many of them with tangible and intangible values, thus favoring the local necessities. Also, has allowed the prevalence of some ancestral rituals that maintain the bond and respect between local campesinos with nature.

The persistence of slash -and-burn practices followed by fallow seasons has allowed tropical dry forest to regrow while avoiding the intrusion of exotic species. Tezcaleras, like other TAS, have been regarded as low-yielding and damaging due to slash and burn. However, our results indicated the opposite: tezcaleras has proven to be a sanctuary for agrobiodiversity, including numerous endemic species, and/or in one of the risk categories.

Regarding crop productivity, they produce enough for families 'subsistence and occasionally for sale. The most serious issues are the uncontrolled use of herbicides and the introduction of perennial crops, such as the Agave crop, which are displacing annual and native crops and potentially affect native wild and agrestal agrobiodiversity. The introduction of technology has also altered social organization. Campesinos used to band together to aid one another in sowing, weeding, and harvesting. In recent years, most of them have found work outside of the town, so they do not have time to participate in this community organization. It is also difficult to find peones (laborers) from the local communities.

Efforts must be made to protect tezcaleras, promote their products for local and regional consumption, and support local farmers in continuing their traditional crops and management practices. Thus, tezcaleras can exemplify a sustainable traditional agriculture system and a biocultural unit in the Balsas region.

Supplementary material

Supplemental data for this article can be accessed here: https://doi.org/10.17129/botsci.3422

Supplemental material.