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Revista mexicana de ciencias agrícolas

versión impresa ISSN 2007-0934

Rev. Mex. Cienc. Agríc vol.7 spe 14 Texcoco feb./mar. 2016

 

Articles

Timber trees in the cocoa agroforestry system in Cárdenas, Tabasco, Mexico

Facundo Sánchez Gutiérrez1 

Julián Pérez-Flores2  § 

José Jesús Obrador Olan2 

Ángel Sol Sánchez2 

Octavio Ruiz-Rosado3 

1Universidad Autónoma de Chiapas-Escuela Maya de Estudios Agropecuarios. Playas de Catazaja. (sanchez.facundo@colpos.mx).

2Colegio de Postgraduados-Campus Tabasco. Periférico Carlos A. Molina s/n, km 3.5, A. P. 24 Cárdenas, Tabasco, México. C. P. 86500. (obradoro@colpos.mx; sol@colpos.mx).

3Colegio de Postgraduados- Campus Veracruz. Carretera Federal Veracruz-Xalapa- Vía Paso de Ovejas, km 26.5. A. P. 421, Veracruz, Veracruz, México. C. P. 91700. (octavior@colpos.mx).

Abstract

In order to study the timber resources of the cocoa agroforestry system (cocoa AFS) in Cárdenas, Tabasco, Mexico, 20 sites of 5 000 m2 (100 x 50 m) were sampled, and the trees present in the sites were identified taxonomically and georeferenced. Diameter at breast height (DBH1.3m), total height (Ht) and clean bole height (Hc) were measured on each tree, and DBH was correlated with Ht. Basal area (BA, m2 ha-1) and total and commercial volume were also calculated (VT, VC, m3 ha-1). The products to be obtained from the stand were defined in function of DBH. The 2 856 trees registered belonged to 67 species grouped in 28 families and 58 genera. Erythrina americana Mill., Cedrela odorata L. and Gliricidia sepium (Jacq.) Walp. were the most frequent species. Mean basal area was 18.6 m2 ha-1, ranging from 8.3 to 34.6 m2 ha-1. Mean VT was 192.4 m3 ha-1, ranging from 70.4 to 619.9 m3 ha-1. Average VC was 52.6 m3 ha-1, ranging from 21.86 to 146.6 m3 ha-1, respectively. From the total sampled trees 66.4% were considered useful for sawmilling, having DBH ≥15 cm. Correlation between DBH and height of the tree species in the cocoa AFS was low but significant (r2= 0.48, p = 0.05).

Key words: Cocoa agroforestry system; dasometry; timber resources; tree diversity

Introduction

Worldwide there are approximately 400 million hectares managed in agroforestry systems (AFS) (Watson et al. 2000). Agroforestry systems are defined as those that include a set of land management techniques for combinations of crops, livestock, or both, and forest. The systems can be established simultaneously or stepwise over time and space (Combe and Budowski, 1979). These systems possess a broad spectrum of plant associations and strong potential for production of timber, firewood, fruits, medicines, forages, oils and ornamental plants, as occurs in the cocoa AFS (Sotomayor et al., 2008).

Cocoa AFS is possible since cocoa crop requires low radiation. Then it is established under a tree canopy, (70% of cocoa is cultivated in association with shade trees and/ or with annual and perennial crops (Salgado et al., 2007), although in Africa, Malaysia, Peru, Colombia and Ecuador cocoa production systems under full sunlight have been developed (González, 2005). Having a broad diversity of tree species, AFS are considered as conservation sites for resident and migratory birds; they contain a high diversity of plants and have an important role in the protection and conservation of biodiversity and carbon storage (Parrish et al., 1999; Roa et al., 2009). Moreover, the tree species contributes to the system’s sustainability by producing forest litter, recycling nutrients and preventing soil erosion (Alvim and Nair, 1986). Salgado et al. (2007) point out that cocoa AFS provide favorable habitats for birds, benefic insects and mammals, as well as sites for conservation of flora.

The flora of cocoa AFS has been described in different studies which include shade trees (Ramírez-Meneses et al., 2013). García (1983) reported that the species Erythrina americana Mill, Diphysa robinoides Benth, Gliricidia sepium (Jacq.) Walp, Samanea saman (Jacq.) Merr. and Colubrina arborescens (Mill.) Sarg. are the most outstanding shade trees of the cocoa AFS in Comalcalco, Tabasco, Mexico. Cocoa producers also introduce other species of their preference useful by their timber (Cedrela odorata L.) and fruits as Mangifera indica L., Citrus spp., and Pouteria sapota (Jacq.) H. E. (Garcia, 1983; Cordova et al., 2001). In Nigeria, cocoa is associated with Cola nitida, which is considered as industrial species (Salgado et al., 2007), while in Costa Rica it is associated with Cordia alliodora, Citrus spp., Cocos nucifera, Inga spp. and Cedrela odorata (Somarriba et al., 2003).

The most common uses for trees in the cocoa AFS are medicinal, timber, pillars for constructing houses, fence posts, tool handles, fruit production, shade for cocoa, firewood, ornamental and roofing for houses (Ramírez-Meneses et al., 2013). Somarriba et al. (2003) and Orozco and Somarriba (2005) reported that 34% of the trees in cocoa plantations in Costa Rica and 15% in Bolivia are used for thick boards in function of their diameter at breast height (DBH1.3 m).

In the upper stratum of the cocoa AFS (more than 20 m high), the tree species S. saman, D. robinoides, Guazuma ulmifolia, G. sepium, C. arborescens, C. alliodora, Terminalia ivorensis and Tabebuia rosea stand out. The trees in this stratum reach a height of 36 m, DBH of 137 cm and average basal area from 11 m2 to 47.2 2 m2 ha-1 (Somarriba et al., 2003; Ramirez-Meneses et al., 2013). Somarriba et al. (1996) reported that C. alliodora, T. ivorensis and T. rosea had the greatest timber volume in the cocoa AFS. FHIA (2007) reported that Cordia megalantha, Tabebuia donnell, Cojoba arborea and Vitex gaumeri, had the largest timber volume in this system, and Somarriba and Domínguez (1994) had similar results but for T. ivorensis, C. alliodora and T. rosea.

Since timber production would complement cocoa production, the present study was conducted to identify the forest tree species present in the AFS and determine the timber volume in the municipality of Cárdenas, Tabasco. Tabasco possesses 41 117 ha of cocoa AFS and produced 16 560 t of dry cocoa in the year 2010. It is the Mexico’s largest producer state. Cárdenas with an area of 10 487 ha of cocoa AFS is the second main cocoa-producing municipality of Tabasco (SIAP, 2011).

Materials and methods

Study area

The study was conducted in cocoa AFS in different localities of the municipality of Cárdenas, Tabasco. Cárdenas is located in the Chontalpa region (17º 59’ N; 91º 32’ W) at an altitude of 2 to 17 masl. Climate is hot-humid with mean annual precipitation of 2 643 mm and a monthly mean of 355 mm; mean annual temperature is 26 ºC with a maximum of 45 ºC (CNA-SMN-SCDI, 2012).

Sampling sites

Twenty experimental plots 50 x 100 m were set up on Eutric Fluvisols (FLeu) and Eutri-gleyic Fluvisols (FLeugl), which are the representative soils of the study area and of the cocoa-AFS (Palma et al., 2007). In addition to the field observations, authorities of each locality were interviewed to contact cooperating producers and to select the cocoa AFS to sample.

Tree flora composition and dasometric variables

The age and area of the cocoa AFS were recorded within each sampling site. The trees were identified taxonomically and georeferenced with a GPS (Garmin model GSmap60csx®) and assigned a number that was painted on the tree with spray paint (Zarco et al., 2010). The dasometric variables recorded were: diameter at breast height (DBH1.3 m, cm) measured with a diametric tape; total height (Ht, m) and commercial bole (Hc) measured with a Haga® Pistol; basal area (BA, m2) estimated with the equation BA= 0.7854 x DBH2 in which, 0.7854= constant; total and commercial volume (TV, CV, m3) estimated with the equation V= BA x ff x H, where: ff= form factor (0.70) and H= total or commercial height (Dauber, 1997; FAO, 2004).

Classification of canopy based on height and DBH and potential use of trees

Tree canopy was classified following the criteria proposed by Pinelo (2001): very low stratum (<5 m high), low (≥5 - <15 m), medium (≥15 - <25 m), and high stratum (≥25 m high). Information on DBH of trees was organized by diametric category at intervals of 10 cm (1 to 10, 10 to 20...) to determine the frequency of each class with respect to the total classes (Orozco and Somarriba, 2005; Zarco et al., 2010). The potential products to be obtained from individual trees were defined in function of DBH: without use (DBH < 5 cm), firewood (≥5 - <10 cm), posts (≥10 - <15 cm), narrow boards (≥15 - <30 cm), thick boards (DBH ≥30 cm) (Mora and Hernández, 2007).

Results and discussion

Ten of the 36.5 ha of cocoa AFS visited were sampled. The average area of the AFS was 1.8 ha, ranging from 0.5 to 5 ha indicating that cocoa plantations belong to the small producers. Somarriba et al. (2003) reported an average area of 1.3 ha, varying from 0.25 to 15 ha in Talamanca, Costa Rica.

Tree flora composition

In the 10 ha sampled it was found 2 856 forest trees, 67 species belonging to 58 genera and 28 families. Ramírez-Meneses et al. (2013), sampled 6 ha in Tabasco Mexico and found 38 species, 35 genera and 24 families. García (1983), also in Tabasco, recorded 40 species of 19 families in a survey of 72 producers, while Salgado et al. (2007) in the Soconusco region in Chiapas Mexico recorded 790 trees belonging to 23 families, 38 genera and 47 species in 7.2 ha. In our study a broader diversity of species and families were recorded than that reported by Garcia (1983) y Salgado et al. (2007). In contrast, Rosa (2003), in Brazil, recorded a smaller number of trees (2 514) but a larger number of species and families (293 and 52 respectively), probably because the cocoa AFS were found in cleared rainforests areas or because the sampling area was larger (15 ha). Moreover, in Nigeria Do and Odebiyi (2007) reported 487 trees belonging to 45 species and 24 families in 1.3 ha.

The average number of species per hectare was 14, ranging from 6 to 35. The most common species were E. americana and C. odorata. Orozco and Somarriba (2005), in Bolivia, reported Swietenia macrophylla, Schyzolobium parahyba and Amburana cearensis. as more frequent species per hectare.

In this study, mean density was 286 trees ha-1, varying from 96 to 618 trees ha-1. The families Fabaceae and Meliaceae were more predominant. In Panama and Costa Rica, Somarriba et al. (1996; 2000) recorded 278 trees ha-1; Mogollon et al. (1996) in Venezuela reported 300 trees ha-1, while Rosa (2003) in Brazil reported from 47 to 355 trees ha-1. The four studies mentioned coincide with ours in tree density per hectare, and also in that the Fabaceae family was the most frequently used for shading the cocoa crop.

Frequency of tree species by plantation age

The age of cocoa AFS sampled varied from 6 to 35 years-old Table 1). In this entire range of ages, Mote (E. americana), 28.4%, Spanish cedar (C. odorata), 20.1%, and Cocoite (G. sepium) 8.7% were outstanding. This agree with Cordova et al. (2001) who reported 25% E. americana in Cárdenas, Tabasco, but contrasts with this same study for G. sepium (75% of the shade trees). Rosa (2003) in Brazil indicated that the most frequent species used to shade cocoa were Schefflera morototoni (Aubl.) Maguire, and Artocarpus heterophyllus Lam., with 8 and 7%, respectively. In Nigeria 10 species accounted for 76% of the trees recorded: Elaeis guineensis Jacq., Cola nitida (Vent.) Schott et Endl., C. sinensis, Mangifera indica, Anacardium occidentale L., Psidium guajava L., Persea americana Mill., Ricinodendron heudelotii Muell. Arg., Citrus reticulata L. and Cocos nucifera L. (Oke and Odebiyi, 2007). In Talamanca, Costa Rica, C. alliodora, Citrus spp., C. nucifera, Inga spp., and C. odorata were outstanding (Somarriba et al., 2003), but in Bolivia the outstanding species were S. macrophylla, S. parahyba, A. cearensis, Centrolobium ochroxylum and C. odorata (Orozco and Somarriba, 2005). These studies, compared with ours, recorded similar species but different density, which is reasonable since the species used for shade in the cocoa AFS vary not only among countries but also among regions of the same country.

Table 1 Frequency of species according to the number of trees recorded in cocoa AFS of different ages, Cárdenas, Tabasco, Mexico. 

In 6-, 20- and 25-year-old cocoa AFS, the most frequent tree species used to shade the cocoa AFS was C. odorata, with a frequency of 78.0, 41.9 and 15.1%, respectively. In 15- and 20-year-old plantations G. sepium was the most frequent with 35.1 and 27.1%. Erythrina americana was the most frequent in the 18-, 25- and 30-year old cocoa AFS with frequencies of 46, 45.4 and 56.6%, respectively. Tabebuia rosea was most frequent in plantations 18- and 35-years-old with 15.2 and 15.8%. Diphysa robinioides was the most frequent in 27- and 33-year-old plantations accounting for 47.8 and 38.5%. In 30-, 33- and 35-year-old plantations, C. arborescens was most frequent with 17.5, 12.8 and 16.9%, respectively (Table 1).

Species with greater basal area by age of cocoa AFS

The 20-year-old cocoa AFS had the smallest BA and the 25-year-old AFS the largest: 12.2 and 22.7 m2 ha-1, respectively. The three forest species with the largest BA in the sampled AFS (6 to 25 years old) were E. americana (6 m2 ha-1), E. poeppigiana (3.8 m2 ha-1) and C. odorata (1.6 m2 ha-1), while each of the remaining 64 species had a BA of ≤1 m2 ha-1 (Figure 1).

Figure 1 Species with the largest basal areas (m2 ha-1) in cocoa AFS of different ages in Cárdenas, Tabasco, Mexico. 

Cedrela odorata was the outstanding species in BA in both 6- and 20 year-old cocoa AFS (15.7 and 2.2 m2 ha-1, respectively). Guazuma ulmifolia was outstanding in 6- and 18-year old cocoa AFS (0.6 ad 1.9 m2 ha-1). In those cocoa AFS aged 15, 25 and 30 years, it was E. poeppigiana (7.8, 9.1 and 1.9 m2 ha-1). Gliricidia sepium had the largest BA in 15, 20 and 35-year-old AFS (4.3, 2.7 and 3.5 m2 ha-1), E. americana in AFS aged 15, 18, 25 and 30 years (3.3, 8.3, 8.2 and 14 m2 ha-1), M. indica in 18-, 30- and 33-year-old AFS (1.4, 0.9 and 2.6 m2 ha-1); S. saman in 25- and 33-year-old AFS (1.7 and 7 m2 ha-1). The 27-, 33- and 35-year-old ASF shared D. robinioides as the outstanding species in BA (3.5, 2.5 and 1 m2 ha-1) (Figure 1).

Basal area (BA) of all the registered trees was 185 m2, with a mean of 18.5 m2 ha-1 and a range of 8.3 to 34.6 m2 ha-1. Ramirez-Meneses et al. (2009) in Cárdenas, Tabasco, reported a mean of 48.2 m2 ha-1, highlighting the species S. saman (12 m2 ha-1), D. robinoides (7.8 m2 ha-1) and G. ulmifolia (5.6 m2 ha-1). These values are higher than those found in our study since the species are of larger diameter and higher frequency (S. saman).Somarriba et al. (1996), in Panamá, reported a mean of 11 m2 ha-1; the species C. alliodora (12 m2 ha-1), T. ivorensis (11 m2 ha-1) and T. rosea (10 m2 ha-1) had the largest BA. Concha et al. (2007) in Lima, Peru, reported average BA of 5.71 m2 ha-1 and the species with the largest BA were Inga sp, Citrus nobilis and Piptadenia favia. Somarriba and Domínguez (1994), in Costa Rica, reported an average BA of 4.1 m2 ha-1; the outstanding species were T. ivorensis (52 m2 ha-1), T. rosea (4.5m2 ha-1) and C. alliodora (2.8 m2 ha-1). FHIA (2007), in Honduras, reported an average BA of 4.8 m2 ha-1. The four cited authors recorded smaller BA than that of our results because the trees were young and had small diameters.

Total timber and commercial volumes (TV, CV)

There is a large quantity of timber in cocoa AFS that can and should be used in a sustainable way. A TV of 1 923.8 m3 in logs was found in the 20 sampled sites. The average TV was 192.4 m3 ha-1. It ranged 70.4 to 619.86 m3 ha-1. Ten species accounted for 87.4% of the TV; the outstanding species were E. poeppigiana 33.5% (64.4 m3 ha-1), E. americana 20.9% (40.3 m3 ha-1) and C. odorata 8.1% (15.5 m3 ha-1) (Figure 2). Somarriba et al. (1996), in Panama, reported the species C. alliodora (90 m3 ha-1), T. ivorensis (81 m3 ha-1) and T. rosea (46 m3 ha-1) as having larger volumes than those of our study, as they were established preferentially for shade. The values similar to those reported by FHIA (2007) in Honduras for the species C. megalantha 118 m3 ha-1, T. donnell 33.9 m3 ha-1, C. arborea 33.6 m3 ha-1 and V. gaumeri 32.6 m3 ha-1. Somarriba and DomÍnguez (1994) in Costa Rica reported T. ivorensis with 35 m3 ha-1, C. alliodora with 21 m3 ha-1 and T. rosea with 19 m3 ha-1 TV.

Figure 2 Species with the highest timber volumes (m3 ha-1) in cocoa AFS in Cárdenas, Tabasco, Mexico. 

Commercial timber volume (clean bole) recorded in the 20 sampled sites was 526.29 m3 log, an average of 52.6 m3 ha-1, ranging from 21.9 to 146.7 m3 ha-1. Ten species accounted for 82.9% of the total VC; of these, E. poeppigiana 27.4% (14.4 m3 ha-1), E. americana 18.7% (9.9 m3 ha-1) and C. odorata 11.9% (6.1 m3 ha-1) were outstanding (Figure 3). Calero (2008), in Costa Rica reported to C. alliodora as the species with the largest VC (31 m3 ha-1); this is explained by its preferential establishment for shade. Cedrela odorata had a smaller VC, which was also smaller than that recorded in our study.

Figure 3 Species with the largest commercial volumes (m3ha-1) in the cocoa AFS, in Cárdenas, Tabasco,Mexico. 

Strata of canopy by height

Mean Ht was 10.1 m varying from 2 to 35.5 m; 5.8% of the trees were placed in the stratum of very low canopy (height <5 m). These were new-planted timber species such as C. odorata, T. rosea and C. arborescens. Most of the trees (84.2% of the total) were concentrated in the low canopy (≥5 - <15 m) and 1% in the high canopy (≥25 m) (Figure 4). In this last category were grouped species such as Eritrina (E. poeppigiana), Samán (S. saman) and Chestnut (A. altilis). Ramírez-Meneses et al. (2013) in Cárdenas, Tabasco, also reported some trees of 36 m, mainly of the species S. saman, G. ulmifolia and C. arborescens, evidencing that cocoa AFS contains tree species of similar height to those found in the tropical rainforests. Somarriba et al. (2003) reported up to 30 m for the upper canopy of cocoa AFS in Talamanca, C. R. Somarriba et al. (1996) in Panama and the FHIA (2007) reported average heights of 17 and 13 m, respectively, which are higher than those recorded in our study, probably because the timber species recorded are not pruned.

Figure 4 Trees distribution by height (m) in cocoa AFS in Cárdenas, Tabasco, Mexico. 

Classification of trees by diameter at breast height (DBH1.3m)

DBH values varied from 1 to 146 cm, with a mean of 23 cm. Of the 2 856 trees registered, 91% had a DBH of 1 to 40 cm and among these, 53% had 10 to 30 cm DBH (Figure 5). Orozco and Somarriba (2005) stated that in Bolivia 45% of the trees in cocoa AFS had DBH of 10 to 20 cm, while Ramirez-Meneses et al. (2013) reported a maximum DBH of 137 cm for some species in Cárdenas, Tabasco. Somarriba et al. (1996) in Panamá and FHIA (2007) in Honduras reported average DBH of 25 and 28 cm, respectively. Both authors reported larger DBH than those found in our study, probably because they averaged only three timber species, while we averaged all the timber species found in the cocoa AFS.

Figure 5 Categories of trees by diameter at breast height (DBH1.3m) of the cocoa AFS in Cárdenas, Tabasco, Mexico. 

Potential use of trees in function of diameter at breast height (DBH1.3 m)

According to the DBH, the main timber uses of the registered trees were narrow and thick boards, 39 and 27.4%, respectively, and 6.9% of the trees were recorded without any use (Figure 6) because they were reforestation species established in areas without shade. Use varies with species, age, diversity and culture, among other factors. Somarriba et al. (2003), in Talamanca, Costa Rica, registered 34% of the trees with use for thick boards, and Orozco and Somarriba (2005) in Bolivia reported 15% with this use.

Figure 6 Potential timber use by diameter at breast height (DBH1.3m) of trees from the cocoa AFS in Cárdenas, Tabasco, Mexico. 

Conclusions

In cocoa AFS in Cárdenas, Tabasco, is present a wide diversity of tree species important for conservation of biodiversity. The most common species used as shade trees were E. americana, C. odorata, G. sepium, C. arborescens and D. robinioides. Moreover, because of the large quantity of tree species found in cocoa AFS, there is a timber volume that can be used sustainably in different ways. The species with the largest timber volumes were E. poeppigiana, E. americana, C. odorata, S. saman and G. sepium. The principal uses of the trees in function of their diameter at breast height (DBH1.3 m) were narrow boards and thick boards.

Acknowledgements

The authors are grateful to LPI-2 and LPI-8 of the Colegio de Postgraduados, for the support received to conduct this research.

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Received: October 2015; Accepted: January 2016

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