Area of Study

Coatetelco is in the municipality of Miacatlán, in the State of Morelos, Mexico (Figure 1). The community is located at an altitude of 980 meters. The weather is Aw0”(w)(e)g, warm with rain during summer, it is the driest of the sub-humid climates. The average annual temperature is 23.2 °C and the annual precipitation is 821.8 mm (^{García, 1988}); the rain season is from June to September.

Figure 1 Location of the study site in Coatetelco (1), Miacatlán Morelos, (2), México (3). 

The plant community shows fragments of dry tropical deciduous forest, where species with fruit, medicinal, ornamental and firewood value are found. Some of the fruit plants are plumb (Spondias spp.), guaje (Leucaena spp.), bonete (Jacaratia mexicana A. DC.) and red guaje (Leucaena esculenta [Moc. & Sessé ex DC.] Benth.); among the medicinal ones are cuachalalate (Amphipterygium adstringens [Schltdl.] Standl.), pega hueso (Euphorbia fulva Stapf.), tepeguaje (Lysiloma divaricatum [Jacq.] J. F. Macbr.) and cuahulote (Guazuma ulmifolia Lam.) and among the ornamental ones there are the ceiba (Ceiba spp. Mill.), clavellina (Pseudobombax ellipticum [Kunth] Dugand), palo dulce (Eysenhardtia polystachya [Ortega] Sarg.) and morning glory (Ipomea spp.). There are also the mesquite (Prosopis spp.) and the cubata (Acacia spp.) that are used as firewood, and copal (Bursera spp.), which has a mystical and religious value (^{Monroy & Ayala, 2003}).

According to the catalog of localities SEDESOL (^{Secretaría de Desarrollo Social, 2013}) there are 9,094 people in the community. Coatetelco has Nahuatl origins (^{Reynoso & Castro, 2002}) and it is considered a marginalized community (^{Consejo Nacional de Población CONAPO, 2010}). The main economic activities in the area are agriculture, fishing, cattle farming and trade. Because of the mentioned economic characteristics, the inhabitants keep alive many of the traditions related to plants (^{Reynoso & Castro, 2002}), some of them linked to the TFH, which motivated the choosing of this place to carry out the research.

Selection of homegardens

The number of homegardens was determined with the accumulation method of the species observed in relation to the number of visited homegardens, it means, it is expected the list of species is bigger by increasing the number of sampled homegardens, but after certain homegardens threshold, the number of species becomes constant. The constant relationship indicated that the maximum number of possible species to be found in the studied area was obtained (^{Moreno, 2001}). The decision taken with this method was to work in 30 homegardens of the locality. The sampling unit for the registration of arboreal species was the entire homegarden. The homegardens were classified into small ones (0-500 m2), medium size ones (501-1,000 m2) and big ones (1,001-1,500 m2).

Arboreal Structure of the homegardens

Species identification. Three botanical samples were collected of each arboreal specie by sample unit, later they were dried and processed at the herbarium “MORE” of the “Universidad Autónoma del Estado de Morelos (UAEM)” The taxonomic determination was done with identification guides (^{Dorado, Flores-Castorena, Almonte, & Martínez-Alvarado, 2012}; ^{Guizar-Nolazco, & Sánchez-Vélez, 1991}), taxonomic keys (^{Calderón & Rzedowski, 2001}) and by the comparison with samples at the herbarium. The scientific names were validated at the webpage ^{The Plant List (2016)}.

Obtaining the Importance Value Index (IVI). The total area of each TFH was registered, number of individuals per species and the basal area estimated with the diameter at the height of the chest. This data were used for the estimation of the parameters that define the structural parameters, the density (individuals∙m2) and the dominance estimated with the basal area; the frequency was not calculated because it only one homegarden per place was taken into consideration. The IVI of the species in each homegarden was obtained having the previous information in mind, through the ^{Cox formula (1985)} modified (IVI = relative density + relative dominance). The maximum result expected of IVI was 200 %.

Relationship of the richness and density of species with the size of the homegarden

The relationship of richness and density of the species with the areas of TFH was determined through the analysis of linear regression (^{Anderson, 2003}), also the correlation coeficient was obtained from Spearman (^{Gibbons & Chakraborti, 2010}). The analysis was done with the program SAS/STAT® version 9.0 (^{Statistical Analysis System Institute Inc. [SAS], 2002}); the size of the homegardens was the independent variable (x), in regard to the richness and density were the dependent variables (y), according to the equation:

Y=β0+β1x+ ε

Cultural Importance of the homegardens

Interviews to the homegarden residents. Semi-structured interviews were appllied in each homegarden (^{Gispert et al., 2009}), they were focused in knowing the common names of trees, their value in use, the destination and the production dates, and management practices.

Obtention of the Cultural Value Index (CVI). Cultural Value Index (CVI) of the present work is different from others because instead of applying the sum of variables (^{Colín-Bahena, Monroy-Martínez, & Rodríguez-Chávez, 2016}), the estimation was made based on the weighted values; in other words, the high value (8) represented the fruit value in use (VU), the most mentioned one, then in decreasing order, medical (7), shade (6), firewood (5), living fence (4), ornamental (3), recreational (2) and fence (1). The sum of the values of use mentioned for each species in each homegarden (ΣVU sp.∙homegarden-1), was divided by the sum of the values of use of all the species (ΣVU spp.∙homegarden-1) to obtain the cultural value index:

CVI=∑VUsp.   ∙homegarden-1∑VUspp.  ∙ homegarden-1

Relationship between indexes

The information derived from (IVI) and (CVI) was submitted to an analysis of regression to know the relationship between both variables. The IVI and CVI of each species in each homegarden were added together and were standardized with ln(x) to adjust the data to a normal distribution, verified through a Shapiro- Wilk (^{Taeger & Kuhnt, 2014}) test. Once obtained the normalized values for each specie, the correlation with Pearson’s coeficient (^{Gibbons & Chakraborti, 2010}) it was calculated in SAS/STAT® program versión 9.0 (^{SAS, 2002}). The CVI represented the independent variable and the IVI the dependant variable.

Characteristics of Homegardens

The traditional fruit homegardens of Coatetelco, in general, have a rectangular shape and area between 220 and 1,500 m2. Women decide what species to stablish in the homegarden and which of the native species from the tropical deciduous forest will stay inside the homegarden; the men and children collaborate in tree pruning, fruits harvesting, among other activities. Land destinated for homegardens varies in size due to different reasons. One of the main ones is possesion of the area and its use, for one or many families. In general, big homegardens are home of many families and the land can or cannot be fractionated, while small homegardens belong to one family.

Arboreal Richness of the Homegardens

The accumulation curve indicated a maximum of 65 arboreal species. This number was kept constant from homegardens 26 to 30; 26 homegardens represent the maximum threshold number of expected species by homegarden in Coatetelco. The interviewees mentioned 62 common names; one specie had two names and four did not have common name. From the 65 trees, 61 were identified at a specie level, two at genus and two were not identified because of the lack of reproductive structures (Appendix 1). Figure 2 shows the 24 registered families, the best represented one was Fabaceae (11 species, 18 %), followed by Anacardiaceae and Rutaceae (seven species, 11 % per each family), similar to what was found in the tropical deciduous forest of the Huautla mountain range for the Fabaceae (^{Arias, Dorado, & Maldonado, 2002}). The comparison of the managed environment and the natural one is interesting because it reflects two important qualities of the human criteria: the interest for the conservation of the native resource original from the tropical deciduous forest that surrounds the homegarden, based on the attributed value in use; and the practice of tolerance-auspice of native species inside the homegarden, important action that with time will lead to domestication of those wild plant species. The richness of arboreal species of Coatetelco was superior to the nine species that were found by ^{Gispert, Colín, Monroy, Vales, and Vilamajó (2012)} in Acamilpa homegardens, municipality of Tlaltizapán, Morelos, which might be due to the fact that the homegardens in this locality have small surfaces, between 250 and 300 m², while in Coatetelco they measure up to 1,500 m².

Figure 2 Number of genera and species of the tree families found in traditional fruit homegardens in Coatetelco, Morelos. 

Table 1 shows the 10 species with high IVI and CVI in the TFH of Coatetelco. The main characteristics of these species is that they have multiple use, except for the Citrus aurantiifolia (Christm.) Swingle that has only fruit use. Species are sold in the market, same as native species of the tropical deciduous forest (^{Zizumbo & García, 2008}) like Leucaena leucocephala (Lam.) De Wit, L. esculenta, Spondias purpurea L. and Pithecellobium dulce (Roxb.) Benth. The most important species in Coatetelco because of their CVI were also documented with high values in use in other studies, as it is the case of L. esculenta (^{Maldonado et al., 2013}) and Mangifera indica L. (^{Gispert et al., 2012}). This last one has become culturally important because of its economic value; in other words, inhabitants of Coatetelco adopt introduced species, keep then in their homegardens and make part of their culture, because they obtain fruit that represent satisfiers for self-consumption and sell.

Table 2 shows the species with low IVI and CVI in Coatetelco which were registered in one homegarden only, among them some native ones from the tropical deciduous forest like A. adstringens, Enterolobium cyclocarpum (Jacq.) Griseb. Swietenia humilis Zucc., Ceiba aesculifolia (Kunth) Britten & Baker f. e Ipomoea pauciflora M. Martens & Galeotti. Such species have different uses to the fruit, some are medicinal and some others are used as firewood. The presence of S. humilis is important for the owner of the homegarden because he/she sells the seeds in the local market for medicinal use against stomach-ache and diarrhea. The homegarden is transcendent for such native species since it works as a genetic reservoir of a resource present in the list of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (^{CITES, 2016}), although it is unknown for the land owner. In the case of C. aesculifolia, the species was not important, according to CVI since it is only use for shade; on the other hand, in Southeast Mexico, a species belonging to the same genus (Ceiba pentandra [L.] Gaernt.) is considered sacred and is used food, for handcraft, building, industrial, for wood, medicinal and ornamental purposes (^{Mariaca, 2012}).

Other species with low IVI and CVI are the introduced as Moringa oleifera Lam., Ficus carica L. and Citrus grandis (L.) Osbeck; its consumption is not common in Coatetelco. In the case of M. oleifera, the species was recently introduced from India because of the medicinal properties in its leaves but it has no fruit value in use.

The cultural importance is related to each region’s features, through learning and knowledge accumulation about the multiple use of species that compose the biodiversity and its ecosystems (^{Monroy, 2009}; ^{Casey & Wynia, 2010}).

Area of the Homegardens

Family decisions have fragmented homegardens due to distribution of land as heritage between offsprings. As a consequence of that, 40 % of homegardens have areas between 223 and 500 m2, 37 % between 501 and 1,000 m2 and 23 % between 1,001 and 1,500 m2. The relationship between homegarden area and richness of species represents high dispersion of data and low determination coefficient (β₀ = 8.0699, β₁ = 0.0054, P-value < 0.0001, R2 = 0.2209); however, the slope is positive and significant, which indicates that richness in homegardens increases with each additional meter (Figure 3).

Figure 3 Relationship between richness of species and area of the traditional fruit homegardens (TFH) in Coatetelco, Morelos. 

The relationship between the surface of the homegarden and the density was positive even though it presents high dispersion of data and correlation coefficients (0.22) and low determination (β0 = 19.4150, β1 = 0.0123, P-valor < 0.0001, R² = 0.0484), which means that the density in homegardens increases with each additional meter because the slope is positive and significant (Figure 4). The aforementioned means that at larger area of the homegarden greater are the density and richness of the species, therefore, a reduction of the surface means a decrease of the density and richness of the species.

Figure 4 Relationship between density and area of traditional fruit homegardens TFH in Coatetelco, Morelos. 

According to IVI and CVI, the loss of species by area of homegarden would affect present species introduced, like C. grandis, F. carica and M. oleifera and some large native species from the tropical deciduous forest, like A. adstringens, S. humilis, J. mexicana and E. cyclocarpum. In regard to M. oleifera, it is known that the plant was taken to the homegarden without particular interest but probably as time goes by it will be taken advantage of the different documented uses (^{Anwar, Latif, Ashraf, & Hilany, 2007}) and even multiplied, since this type of plants with potential value in market can influence culture by generating new habits and use patterns.

Values in use of the Traditional Fruit Homegardens

Out the total of species, 57 % presented multiple use whereas 43 % registered only one value in use, similar to the indicated by Colín et al. (2016), who reported 59 % of species with multiple use. The values in use were eight: shade (36 %), fruit (35 %), ornamental (10 %), firewood (8 %), medicinal (6 %), living fence (2 %), recreative (2 %), and fence (1 %). The shade is used for protection against solar radiation in different areas: house, laundry area, patio, living fences, and as benefit for other plants. The fruit species are used for fruit and due to its cultural importance the term traditional fruit homegarden is obtained. On the other hand, ornamental species are generally appreciated because of the looks of their flowers; in the case of plants for medicinal use, their leaves, bark and seeds are used. Firewood comes from the pruning of tree branches which compose a living fence and the continuous trimming of branches are used to set land limits, while recreational use is for trees where swings and hammocks hang from.

Production in homegardens is carried out all year long, although the months with greater fruit harvest of 19 species belong to the dry season, during April and May, among them some native from the tropical deciduous forest like S. purpurea, J. mexicana and P. dulce, contrary to what was found by ^{Colín, Hernández-Cuevas & Monroy (2012)}, where summer months are the ones of the least production. The aforementioned represents a big contribution for marginalized communities like Coatetelco, since the production means earning for self supply and selling at the time when there is a shortage in other localities. The production of trees in other 19 homegardens is used for self supply and at 11 homegardens, fruit and medicinal plants are also obtained to be sold at the local market.

The IVI and CVI had a positive relationship 86 % (P < 0.0001) (Figure 5). Species with high value in use are more important in biocultural terms, as a similar result found by ^{Maldonado et al. (2013)}, but different from the one of ^{López-Toledo & Valdez-Hernández (2011)}, study where the species with high CVI values presented low IVI which was attribuited to loss of traditional knowledge.

Figure 5 Relationship between importance value index and cultural value index of the arboreal species of traditional fruit homegardens TFH in Coatetelco, Morelos.