Study area

Fieldwork was conducted in El Ejido Encrucijada 3^rd Section (Las Calzadas), Municipality of Carde nas, Tabasco, located at 18° 15' 25'' North latitude and 93 ° 33' 16'' West longitude, and counts with 1505 inhabitants. The topography is a floodplain, with an altitude of 5m and its current vegetation is grassland (^{INEGI, 2010}).

The climate is warm humid (Am) with abundant rains in summer, this climate covers the Tabasco plains, both the base and the east slope of the Sierra Madre Oriental and on the slope from the Pacific of the southeastern portion of the Sierra Madre from Chiapas (García, 1973). The average annual temperature is 26 °C and an average annual rainfall of 2500 mm. Dominant soils correspond to GLvr/2 (Gleysol Vertic) group of medium texture (^{INEGI 2012}). The agricultural potential use corresponds to corn, beans, rice, watermelon and livestock development potential for cultivated pastures with agricultural machinery (^{INEGI, 2012}).

Sample size

In a preliminary tour in the town, informal interviews with local authorities and the use of the sampling frame, the sample size was calculated with the pre-sample formula proposed by ^{Abdoellah et al. (2006)} to obtain 29 home orchards.

Where: n= number of samples; N= number of homes with orchards in the study area (92); Z= value of a normal distribution Z_α/2 (1.96) for a confidence level of 95%; p= probability of success (0.5); and d= sampling error (0.15). Subsequently a meeting with the families in a known location of the town was convened to seek their support and consent, explain the research objectives, stages and activities to do in their home orchards. To locate the sampling units, a flat freehand map was developed with the help of the local authority, which was used to support field guide.

Socioeconomic data collection

First a survey was applied to each householder or responsible in managing the family orchard to obtain socioeconomic information such as family members, sex, age, education, economic activity and land tenure. The socio-economic importance was determined considering the use of plants for consumption and savings for consuming products from the home orchard.

Collecting biophysical data

Considering plant distribution during the preliminary fieldtrips, it was determined to collect the information in two stages; the first consisted on conducting a floristic inventory of woody species, perennial herbs and palms, excluding annual herbs. In the second stage a 16 m² quadrant was established in every home orchard to mainly include annual grasses. The size of the quadrant was determined considering as the main criterion plant density, which was supported with a basic question addressed to the owner, What is the main area of useful herbs for family ?, also the size used served to standardize and compare the sampling units (^{Mostacedo and Frederiksen, 2000}).

The quadrants were drawn with a stick graduated each meter and at the ends were marked with small stakes. In both methods, attribute like common name, scientific name, biological shape, uses and part used were recorded. Outstanding data provided by the owners during the tour into their orchards were recorded and photographed unknown plant by their common name.

Species diversity

Species diversity was obtained by the diversity index Shannon-Weaver.

Where: H’= Shannon-Wiener index; Pi= relative abundance (proportion of individuals of the species i); ln= natural logarithm; and S= number of species.

Floristic similarity

The floristic similarity between the sampling units (home orchards) was obtained by Sörensen index.

Where: A= number of species found in community A; B= number of species found in community B; and C= number of species common to both communities. After collecting field data, proceeded to collect a botanical sample of unidentified species in field for identification by taxonomic code (^{Lot and Chiang, 1986}) and with the support from Dr. Ángel Sol Sánchez from the Postgraduate College in Agricultural Sciences, Campus Tabasco. The information was confirmed using scientific sources on home orchards and through photographs obtained in home orchards.

Floristic composition

203 species belonging to 69 botanical families were identified, being the most representative Lamiaceae, Fabaceae and Rutaceae. A total of 1 968 plants were registered, 1576 through floristic inventory and 392 through 16 m² quadrants, being the most abundant, trees (54%) and herbs (67%) respectively. The number of species is close to that reported by ^{Torres (2010)} with 130, ^{Gomez (2011)} with 83, although it is low compared with the first studies of home orchards in the state of Tabasco, as reported by ^{Ortiz (1979)} with 285 species in their study that included the municipalities of Cardenas, Huimanguillo, Nacajuca and Cunduacan, and that reported by ^{Romero (1981)} with 218 in Cardenas and 219 in Cunduacán. A study made by ^{Herrera et al. (1993)} reported 339 species in home orchards from the Yucatan Peninsula.

In this context, it is clear that diversity may differ between home orchards from place to place, from one region to another or from one country to another, however, there are common factors that are affecting species richness, among them are the agroecological factors such as biophysical site conditions, soil fertility, cultural practices and socio-economic framework as lifestyle, socio-economic status, farmers interest, modernization processes influence the variability of richness and species diversity (^{Zimik et al., 2012}).

The best represented botanical families in the floristic inventory were Fabaceae and Rutaceae with eight species each, followed by Malvaceae and Musaceae with seven, while in the 16 m² quadrants corresponded to Lamiaceae (nine species), Araceae, Asteraceae and Rosaceae with six species each. The species from the Fabaceae family like chipilco (Diphysa robinioides Benth.), Mote (Erythrina americana Mill.), Palo sangre (Pterocarpus hayesii Hemsl.) and cuinicuil (Inga jinicuil Schltdl.) associated with cocoa agro-ecosystem, contributing to the wealth of home orchards (^{Escolástico, 1983}).

Species like Terminalia catappa L. and Muntingia calabura L., although they are part of the vegetation of the Ejido, were less common in home orchards, this might be due to the preference of fast-growing plants and steady production as species diversity of banana: valery banana (Musa acuminata Colla), banana bellaco (Musa paradisiaca L.), banana ciento en boca (Musa acuminata Colla), cuadrado banana (Musa balbisiana Colla), dominico banana (Musa paradisiaca L.), manzano banana (Musa sapientum L.) and morado banana (Musa acuminata Colla).

The species richness in the floristic inventory ranged from 4 to 33, regarding orchards with higher richness (27 to 33 species) were characterized by having high density (75 to 160 plants) of fruit and timber, which gave away a complex physiognomy around the housing. In such orchards 33% of the plants, contributing 60% on average to vegetation cover, reflecting the efficient use of space in its horizontal arrangement were recorded. The canopy of vegetation from orchards with greater richness was 7 549.56 m² which represented 92% of 8167 m² of their area, which reflected an efficient use of both vertical and horizontal space, leaving a small open space by vegetation. Moreover, these home orchards were managed by adult members of a family, and both genders participated in all activities, like planting, watering, pruning, and harvesting. ^{Chi (2009)} did not rule out the participation of both genders, but noted that there are activities exclusive for men such as hunting or fishing, as reported by ^{Lerner et al. (2009)}. Age and more labor may influence the diversity and greater richness of home orchards (^{Avarez-Buylla et al., 1989}; ^{Kehlenbeck et al., 2007}).

By contrast, in less rich orchards (four to 11 species), had lower density (31 plants in total) so the coverage was low (1 293.99 m² representing 34% of 3 751.29 m²), recording higher abundance of valery banana (Musa acuminata Colla) and achiote (Bixa orellana L.). The low richness, coverage was because home orchards recorded confined areas to establish plants, which results in fragmentation of ownership; also were located in areas susceptible to flooding, families were not interested in gardening plants and members age, since most were underage, not yet directly involved in managing home orchards.

A frequency analysis of species recorded in the inventory showed the following species in descending order: mango (Mangifera indica L. [in 24 orchards]), coconut (Cocos nucifera L. [22]), orange (Citrus sinensis (L.) Osbeck [21]), pink poui (Tabebuia rosea (Bertol.) A. DC. [20]) and cedar (Cedrela odorata L. [19]). The most common species were identified in all strata; most of these dominated the top strata, except Citrus sinensis (L.) Osbeck that dominated the lower stratum. Mangifera indica L. was the most common species and the most abundant varieties as follows: as banana mango, mamey mango, manila mango, criollo mango, pajaro mango, rosa mango, injerto mango, ataulfo mango and durazno mango, these varieties were reported by ^{Ortiz (1979)}.

It was observed that the floristic composition was dynamic, because families grow plants according to their preferences and needs, always trying to take advantage of all space available and depending on sunlight or shade requirements (^{Fernandes and Nair, 1986}). For example, cocoa trees were placed in the shade and soursop trees were located in open spaces. Furthermore, in each orchard plants were placed according to the available area and preferred areas by the owner.

Herbaceous species were located in areas with less risk of flooding and easy access to be managed. These areas did not show a pattern in its design and plant distribution, but were located somewhere in the housing, regularly next to it to show its beauty and floristic composition, as well as being protected againts pets, avoid theft and were handled primarily by the lady of the house. ^{Coomes and Ban (2004)} reported that the proximity of homw orchards allows families to grow in time and monitore to reduce the risk of theft.

The herbs areas, the 16 m² quadrants were established, its richness ranged from 0 to 16 species, being higher those presenting a clearly defined area, which are not susceptible to flooding during the rainy season (June to November), which differs from areas with low richness. These areas had better management such as weeding and watering, and care by women, which contrasted with the participation of men, since they were devoted to woody plants (^{Romero, 1981}).

In areas of low richness, herbs are planted in pots that are placed in different containers and surfaces (wheelbarrow, tires, stem or tree stump), which facilitated their mobility in case of flooding. ^{Pérez et al. (2012)} considered that the use of different containers for herbs creates a threedimensional space formed by trees, shrubs and perennial herbs as fixed components. Meanwhile, ^{Coomes and Ban (2004)} considered that the annual floods affect the potential of growing plants.

Plants management was based on gender; men managed woody components (fruit trees and multipurpose trees) by the difficulty or skill required to climb and women herbaceous plants (ornamental and medicinal plants). It was identified that women choose the type of plant to introduce and experiment in the orchards, especially ornamental and medicinal herbs, so it was confirmed that women influence the diversity (^{Lerner et al., 2009}) and is more accurate their knowledge on shape and frequency of use in herbal medicines. ^{Adhikari et al. (2004)} considered that gender is a socially constructed role and assigns responsibilities (activities and access to resources) to men and women (including children) in a given culture and place.

The high diversity of herbs that are planted next to the house, reflected on medicinal plants, these were the second category of use in inventories and quadrants. 80 species belonging to 43 botanical families, highlighting the Lamiaceae with 10 species, followed by Asteraceae with sic species and Acanthaceae with five species.

Medicinal plants play an important role in family units, help to counteract various aches and represent the main source of aid. In these cases, the lady of the house is responsible to prepare or elaborate a cure, as reported (^{Chi, 2009}), or in special cases come to a "comadrona" (person who is dedicated to cure with medicinal plants). The current use of medicinal plants, pointed out that even the traditional knowledge of medicinal plants in this rural town, as well as others in the state of Tabasco is preserved (^{Ortiz, 1979}; ^{Magaña et al., 2010}).

Medicinal plants offered a wide variety of uses such as: healing, control blood pressure, lower body temperature, inflammation, wound healing, avoid itching on the body, remove toothache, earache, eliminate cold, lower sugar, heal burn, reduce skin inflation by cutting and removing pimples (newborn), swollen kidney, lower triglycerides, remove colic, deworming, remove diarrhea, asthma, cough, awe sun, lower cholesterol, remove stomach pain, headache, control diabetes, refresh the body, remove foot fungus, avoid bad breath, pull teeth, remove head heating, remove body aches, ulcer, control the nerves and muscle aches.

Biological forms

The biological forms were distributed as follows: tree (54%) with 1053 plants, herbs (33%) with 646 plants, bush (8%) with 161 plants, palm (5%) with 100 plants, biological form climber and vine recorded six and two plants respectively. Biological form dominance of tree coincides with Nair (1985), ^{Gomez (2011)}, the most important component of home orchards. The main role of trees is to provide building material and fruit for human consumption, this coincided in the most abundant species such as Tabebuia rosea (Bertol.) A. DC, and Theobroma cacao L. with 197 and 168 individuals respectively. Medicinal plants recorded four biological forms, being the most abundant in the following order: herbs with 190 individuals (82%), tree with 23 (10%), bush 14 (10%) and vine with four (2%). The parts employed were: leaf (81%), fruit (9%), bark (3%), flower (3%), sap (1%), root (1%), seed (1%) and stem (1%).

Categories of use

Villagers recognize 15 categories of use, being the most abundant ornamental use (30%), followed by food (26%) and medical (16%) (Figure 1). The abundance of the registered uses indicated the traditional characteristics of home orchards (^{Abdoellah et al., 2006}) by reporting mainly medicinal ornamentals, fruits and medicinal, noting that commercial orchards dominate plant and ornamental. Ornamental dominance could reflect the active participation of women to introduce and experiment in home orchards, so it is said to be a women’s space (^{Chávez, 2011}), although home orchards are located along roads or paths fulfilling the role of beautifying home (^{Blankaert et al., 2004}; ^{Peyre et al., 2006}).

Figure 1 Categories of use. 

Categories of use registered resemble to that reported by ^{Ortiz (1979)} and ^{Gómez (2011)}. The categories of ornamental, edible and medicinal use that dominated in home orchards studied by ^{Ortiz (1979)}, ^{Romero (1981)}, ^{Kabir and Webb (2008)} and ^{Chi (2009)}) support the role of traditional home orchards.

From counting the uses given by biological form and category of use, trees had 13 applications, mostly edible, so its main function is to meet food needs of the families (Nair, 1985; ^{Fernandes and Nair, 1986}; ^{Perera et al., 1991}; ^{Kabir and Webb, 2008}). The functions of traditional home orchards are given from a high diversity, climatic conditions, property size, structural arrangement, plant density, management practices and species composition, which vary at local or regional level (^{Pulami and Paudel, 2004}; ^{Sthapit et al., 2004}; ^{Abdoellah et al., 2006}). Meanwhile ^{Subedi et al. (2004)} considered the cultural and religious framework, and to a lesser degree the economic determines the number of usesvalue of crops a home orchard.

In addition to providing satisfactions and savings, the traditional agro-ecosystems such as home orchards, also contribute to food security and play an important role in the conservation of biodiversity and agro-biodiversity in rural communities (^{Pulami and Paudel, 2004}; ^{Sthapit et al., 2004}; ^{Subedi et al., 2004}; ^{Peyre et al., 2006}) thus as productivity, so ^{Kabir and Webb, 2008}; ^{Henry et al., 2009} and ^{Huai and Hamilton, 2009}, noted that home orchards could be a pillar in the conservation, coming to replace primary forests if they were to degrade or where there are none, as in the Ejido La Encrucijada.

Species diversity

The diversity index H’ of species that were inventoried ranged from 0.94 to 3.09, being more uniform and more diverse by increasing the value. The uniformity is related to the relative abundance of species. 76% of sampled orchards showed a tendency to be more uniform and diverse by registering values higher than two. According to ^{Sunwar (2004)} a general rule on the diversity of a particular place may be higher if species are equally distributed in abundance and the maximum value that can reach the H’ index depends on the number of species in the plant community and its uniformity.

The trend to uniformity and high diversity are sustained on Figure 2 and as noted by ^{Kehlenbeck et al. (2007)}. H’ index values do not decrease as the size of home orchards increase, on the contrary, if the values decrease to larger size of home orchards, probably is due to a uniform planting pattern and dominance of few species, as showed in an orchard (arrowed), which dominated the species of Theobroma cacao L.

Figure 2 Correlation between H' index / size of home orchards. 

From a classification of home orchards for its size; (A) very large (x-=2 498 m²), B) large (x-=1 670 m²), C) medium (x-=1 219 m²), D) regular (x-=718 m²); and E) small (x-=429 m²) and its respective diversity index, Student t test was performed. There were no significant differences (p> 0.05) between A-B, A-C, A-D, A-E, D-E and C-E pairs, but in B-C, B-D, B-E and C-D pairs there were significant differences. So size does not necessarily mean greater richness, but perhaps abundance of some species over others and where there were differences, size influenced richness.

Diversity indices obtained are close to that reported by ^{Torres (2010)} for three localities in the municipality of Cardenas, ranging from 2.20 to 3.43 and ^{Ortiz (1979)} intianed an index H’= 2.7 in a community from Cunduacán, both municipalities in the State of Tabasco. According to ^{Coomes and Ban (2004)}, ^{Sthapit et al. (2004)} and ^{Subedi et al. (2004)} the diversity of a home orchard is attributed to factors such as size and structure of the orchard, age of the orchard, exchange of species (including seeds and cuttings) between neighbors or relatives, ecological and climatic conditions, agro-geographical conditions, easy market access, specific needs, tastes, knowledge, culture and experience of the owner as well as the social factor (needs and requirements of the family), cultural and religious framework (preference for certain species).

A calculation of the index H’ from the species recorded in quadrants, ranged from 0.50 to 2.62, being more uniform the distribution of species and greater richness as the value is greater. 28% of the orchards were diverse and showed greater proportion in the distribution of individuals among species with values ≥ 2.04 and <2.63, while 72% was not diverse and there was smaller proportion of individuals among species by recording values ≤ 1.91.

^{Sunwar (2004)} suggested that the use of equity indexes (J) and Simpson (λ) to complement the H’ index because it helps to better assess the diversity of species in home orchards. The first index measures uniformity, the second dominance (greater relative abundance of H’ index) of one or a few common species and H’ index expresses the diversity and measures richness within a plant community. Thus, 76% of the orchards showed uniformity or equal abundance of species, which coincides with the trend to diversity through the H’ index which recorded higher values to tow and 10% was dominated by one or a few species, corresponding to the orchards susceptible to flooding during the rainy season.

The study of the diversity of home orchards is important to establish strategies for conservation of agro-biodiversity at community level, contribute to food security through a diversified diet (^{Sunwar, 2004}) and to continue fulfilling various functions such as subsistence production, to nutrition security in terms of protein, minerals and vitamins, trade (income), socio-cultural and ecological services (^{Kehlenbeck et al., 2007}).

Floristic similarity

The greatest floristic similarity from the inventoried species was present in large orchards pairs (B) and medium (C), which was 74%, indicating that orchards share species and instead those who had lower similarity were the very large (A) and small (E) with a percentage of 56%.

Socio-economic importance

The social importance was related to the following activities and services: a) labor division among family members to manage the orchard; b) the exchange of plants between families and neighbors, which happens in all traditional societies (^{Coomes and Ban, 2004}; ^{Kehlenbeck et al., 2007}); and c) in the yard different family gatherings are made (baptisms, first communion, XV years, weddings) and ejido, it is a place to socialize and children can play there (^{Abdoellah et al., 2006}). Also in the yard are stored the fruits harvested from the orchard or from the cocoa agro-ecosystem, protect firewood, tools, do housework and personal hygiene.

The economic importance relates to; a) the sale of fruits, mainly cocoa, and rarely banana, orange, lemon and pepper; b) savings by consumption of fruits, herbs and vegetables; c) savings by family labor; d) savings by using local materials and inputs (wood, palm leaves, posts, dead leaves, manure from poultry, pigs and sheep); e) production over the year according to production cycles of each species; f) revenues from backyard sales such as: pigs (S. scrofa domestica), turkeys (Meleagris), hens and chickens (Gallus gallus domesticus), ducks, goose (Anser anser), songbirds (Poicephalus), black bellied tree duck (Dendrocygna autummalis) and sheep (Ovis orientalis aries). Revenues from the sale of animals were not recorded in this study.

An estimate on sales and savings from consumption of harvested products in home orchards, recorded a contribution of $122 815 representing 16% of the annual income of all family units which was $ 753 792 for the concept of welfare programs like Prospera, 70 and +, for wages, own business, remittance, sales of cocoa and achiote bread. The sale of cocoa and achiote was supplemented in those households units that also count with cocoa agro-ecosystem (^{Ortiz, 1979}). The contribution from home orchards represented 1/3 of the total income (12.40% to 18%) (^{Chi, 2009}). Sol (2012) and ^{Van der Wal et al. (2011)} reported that if the production of the home orchard is of a similar proportion to consumption and marketing, the sales volume can range from $20 600 to $23 800 a year, including fruits, vegetables and domestic animals per family.

^{Alvarez-Buylla et al. (1989)} reported that family is the socioeconomic unit, productive and responsible for deciding and managing their economic options. A major capital held by the family is the empirical knowledge about the traditional use of plants, orchard management and plant ecology as sunlight and shade requirements, their production cycles, seeds and plants selection, as well as inputs use obtained within home orchards. Such knowledge ranged between members of households and gender. This difference in gender was also in management activities, while men were responsible for the fruit and timber trees; women did it in perennials, ornamental and medicinal herbs.