Potential Management of Chamaedorea seifrizii (Palmae), a Non-timber Forest Product from the Tropical Forest of Calakmul, Southeast Mexico1 LEONEL LOPEZ-TOLEDO*,2,3, CHRISTA HORN3, ANTONIO LÓPEZ-CEN4, RODOLFO COLLÍ-DÍAZ4, AND ANGELICA PADILLA4 2
Centro de Investigaciones en Ecosistemas, Universidad Nacional Autonóma de México, Apartado Postal 27-3 Xangari 58089, Morelia, Michoacán, México 3 Division of Applied Plant Ecology, Institute for Conservation Research, San Diego Zoo Global, 15600 San Pasqual Valley Road, Escondido, CA 92027, USA 4 Pronatura-Península de Yucatán, A.C. Calle 32 No. 269, Col. Pinzón II, Mérida, Yucatán, México C.P. 97207 *Corresponding author: e-mail:
[email protected],
[email protected]
Potential Management of Chamaedorea seifrizii (Palmae), a Non-timber Forest Product from the Tropical Forest of Calakmul, Southeast Mexico. Leaves and seeds of Chamaedorea (xate) palms are important non-timber forest products (NTFPs). In the Calakmul region (Yucatan Peninsula) of Mexico, several communities have sporadically collected and sold seeds of C. seifrizii since 1980. However, harvesting has intensified recently, raising concerns about overexploitation. To evaluate the economic potential of leaf and seed exploitation in the area, we collected information on abundance, population patterns, and leaf and seed stocks in Ejido Conhuas, a community within the Calakmul Biosphere Reserve (CBR). Then we combined these data with current market values and hypothetical management regimes obtained from the literature for leaves and seeds. Conducting a quantitative analysis of 43 0.1ha plots with differences in forest and soil type, we assessed the abundance of C. seifrizzi in the area. We also conducted interviews to estimate the importance of xate in the local economy. We found C. seifrizii density to be highly variable, with a mean (±SE) of 295 (±35), with forest type being the most influential factor. Population structures differ between forest types, with healthy populations in medium and lower forest. We found a mean density of leaves of harvestable size of 3,750 (±380) leaves ha-1, while seed production was 1.5 (±0.3) kg/ha-1 of fresh seeds. Assuming sustainable harvest rates of 30–50% for leaves and 80% for seeds, one hectare of forest could generate USD 7.0–15.9/ha-1. Considering the number of households (102) and 10% of the total area managed each year (5,700 ha), this harvest could generate a household income of USD 391–838 annually. At the moment, xate trade represents a minor component in the economy of the community, but given the area’s extensive forest (>57,000 ha), the resource abundance, and the low human population, we believe the NTFPs derived from C. seifrizii have a potentially great economic impact in the area. Manejo potencial de Chamaedorea seifrizii (Palmae): Un producto forestal no maderable del bosque tropical de Calakmul, sureste de México. Las hojas y frutos de las palmas Chamaedorea (xate) representan un importante producto forestal no maderable. En la region de Calakmul, varias comunidades han recolectado y vendido esporadicamente semillas de C. seifrizii. Sin embargo, la cosecha se ha intensificado y hay preocupaciones de sobreexplotación. Para evaluar el potencial de la cosecha de hojas y semillas en la región de Calakmul realizamos una investigacion de abundancia y de su potencial económico en el Ejido Conhuas, una comunidad dentro de la Reserva de la Biosfera Calakmul. Evaluamos la abundancia de C. seifrizii en 43 sitios de 0.1 ha con diferencias en tipos de bosque y de suelo. Encontramos que la densidad de C. seifrizii es muy variable con una media (±ES) de 295 (±35), siendo el tipo de bosque el factor
1 Received 2 February 2011; accepted 8 August 2011; published online 26 November 2011.
Economic Botany, 65(4), 2011, pp. 371–380 © 2011, by The New York Botanical Garden Press, Bronx, NY 10458-5126 U.S.A.
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mas importante. La estructura de la población difiere entre tipos de bosques con las mejores poblaciones en selva mediana y baja. Las hojas cosechables fueron muy abudantes con una media de 3,750 (±380) leaves ha-1, mientras que la producción de frutos fue de 1.5 (±0.3) kg/ha de fruto fresco. Asumiendo 30%–50% hojas of leaves and 80% de frutos como maximo de cosecha sustentable, la extracción de C. seifrizii generaría USD 7.0–15.9/ha. Considerando un número de familias (102) y el manejo de un 10% del área total de la comunidad (5,700 has), la cosecha de xate podria generar un ingreso annual de USD 391–838 anuales. Creemos que C. seifrizii representa un PFNM con un gran potencial económico. Key Words:
Xate, NTFPs, leaves and seed harvesting, Yucatan Peninsula.
Introduction Commercialization of non-timber forest products (NTFPs) may support both forest conservation and the livelihood needs of forest-based populations (Ticktin 2004). Leaves and seeds of Chamaedorea palms (commonly known as xate in Mexico) are one of the most important NTFPs for rural communities in several regions of Mexico and Central America, representing in some cases up to 75% of a household’s income (Bridgewater et al. 2006; López-Feldman and Taylor 2009). In Mexico, Chamaedorea palms are particularly attractive given its high species richness (about 50 sp.) (Hodel 1992). In the Calakmul region of the Yucatan Peninsula, a highly biodiverse ecosystem and home to the largest tropical protected area in Mexico (Martínez and Galindo-Leal 2002), Chamaedorea’s six species make it the most diverse genus of understory palms. C. seifrizii Burret (Palmae) seems to be the most abundant, as well as the only one with a local market (Padilla et al. 2009). Several communities in the Calakmul region have collected and sold C. seifrizii seeds to the U. S. markets since the mid-1980s (Wilsey 2010), albeit on a small scale. In the past 30 years, colonists from other regions of Mexico and Guatemala have settled in the Calakmul region, threatening the protected area and its high biodiversity by bringing their agricultural and livestock grazing traditions with them (Escamilla et al. 2000). The risk of land conversion has increased, largely due to the lack of economic alternatives (Lopez-Toledo et al. 2011). Harvesting of C. seifrizzi seeds and leaves may represent one such alternative. Recently, seed harvesting has been on the rise to meet increasing demand, and this increase has generated concern about overexploitation, since it occurs without the benefit of a management plan (Padilla et al. 2009).
Numerous case studies have demonstrated the need for resource assessments and management plans, even for NTFPs where only parts, such as leaves or seeds, are harvested (Bernal 1998; Ratsirarson et al. 1996; Svenning and Macia 2002). Palm leaf harvesting rarely results in the immediate death of individual palms. For example, 33–50% of harvestable leaves of C. elegans, C. oblongata, and C. ernesti-augustii can be harvested twice a year without damaging the vital rates (survival, growth, and fecundity) and the population growth rates (Hernández-Barrios 2008; Lopez-Toledo 2003; Martínez-Ramos et al. 2009). By contrast, several studies have noted negative effects of frequent and high-intensity harvests. For instance, 100% of harvesting and two to four harvests a year of C. radicalis or C. elegans may put the population at risk (Endress et al. 2006). The overexploitation of several palm species for their leaves or stems has diminished populations in several tropical areas (Svenning and Macia 2002; Zuidema et al. 2007). Even with xate, the heavy extraction has drawn into question the sustainability of exploiting wild populations (Bridgewater et al. 2006). Some areas have experienced local extinction of certain xate species due to overharvesting, adversely affecting not only the species population, but the people who had come to use the resource and depend on it for income (Bridgewater et al. 2006; CEC-NA 2002; Sanchez-Carrillo and Valtierra-Pacheco 2003). For species with long life cycles, such as palms, few concerns have been raised regarding fruit and seed harvest. Several theoretical and monitoring studies have shown seeds are not as important as other life stages for population stability and that a high proportion of seeds (80–93%) can be removed with relatively low impact on the population dynamic (Bernal 1998; Ratsirarson et al. 1996; Ticktin 2004 and references therein). However, species and location specific studies are
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vital to assess sustainability and potential management strategies of seed removal. We believe information about the abundance of the species is a fundamental step necessary in implementing conservation and/or sustainable management programs. Additionally, understanding the quantity and location of a resource stock is key to developing a permanent source of income for communities. In the last four years the trade of seeds has increased from 1 ton/yr (or less) to 3–4 tons/yr, indicating a growing market for seeds. There is also an emerging market for previously unexploited leaves. This scenario makes it necessary to evaluate the potential impacts of extraction in order to avoid overexploitation. To determine whether sustainable management is achievable and to help local authorities prepare a management plan, it is essential to determine the abundance of the species, the product stocks (i.e., numbers of leaves and seeds), and the areas with higher potential for extraction. This information can then be used to establish a reliable source of income for residents of the Calakmul region while avoiding overexploitation and land conversion. For our study, we collected basic ecological information in order to contribute to the conservation and sustainable use of Chamaedorea seifrizii in the Calakmul Biosphere Reserve (CBR), southeast Mexico. Specifically, we predicted that C. seifrizii density and population patterns vary as a function of forest and soil types. We then evaluated whether or not C. seifrizii can be managed sustainably and whether it can generate a significant income. We addressed the following questions: 1) Where does C. seifrizii attain its highest densities? 2) What is the demographic structure of the populations within the study area? 3) What are the leaf and seed stocks within the study area? Using data from household interviews we also determined xate’s current contribution to local incomes. With these analyses we project the possible income generated from seed and leaf harvesting. We conclude with suggestions for the conservation and future management of the species.
Materials and Methods STUDY SPECIES Xate, or bamboo palm (Chamaedorea seifrizii), is an understory dioecious palm with clonal growth (Hodel 1992). It currently ranks as one
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the most commercially significant Chamaedorea species in the United States. Seeds are used to produce indoor or landscape plants, and leaves are used as foliage in floral arrangements and for Palm Sunday (CEC-NA 2002; Eccardi 2003). Each individual plant (genet) grows by the addition of new shoots (ramets). Within the CBR, C. seifrizii is not larger than 3 m; it flowers and fruits between June and December. Fruits are globose, 10x8 mm in size, and contain one seed. Highly resistant to drought and sunlight intensity, C. seifrizii develops well in the Yucatan Peninsula forest (Hodel 1992). Within the CBR, apart from occasional use as fullsun ornamental plant, local people do not use C. seifrizii. However, local inhabitants have occasionally collected its seeds to sell to intermediaries, who then export the seeds to the U.S. Starting in 2005, the number of harvesters increased, pushing annual extraction to about 3–4 tons a year. Though there are no legal limitations on the commercial sale of seeds, the study area’s status as a protected area necessitates the development of management plans for resource extraction. Despite its growing significance, extraction and selling of xate leaves or seeds has not been organized and there is no management plan for the region. Thus extraction remains illegal.
STUDY AREA The study area consists of 2,400 ha within the forest reserve of the Ejido Conhuas, Campeche, in the southeast of the Yucatan Peninsula. Conhuas is a relatively new community formed in the 1950s by people from Central/South Mexico with little knowledge of the tropical forest of Yucatan Peninsula. Indigenous people representing six different groups constitute 15% of the population; the remaining are mestizo people. A total of 583 people comprising 102 families live in the community. Their main economic activities include agriculture, apiculture, raising livestock, and tourism (Padilla et al. 2009). With 56,358 ha of mostly primary forest, Ejido Conhuas forms part of the Calakmul Biosphere Reserve’s (CBR) buffer zone and it is part of the largest area of tropical forest in Mexico and Mesoamerica (Fig. 1). The most extensive vegetation types are medium tropical semi-evergreen (MTSE) forest, low tropical semi-evergreen (LTSE) forest, and mixed seasonally flooded forest (MSFF). A tropical sub-humid climate with summer rains and a pronounced winter dry period
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Fig. 1. Location of the study area. The inset in a shows the location of Campeche state in Mexico. b the Calakmul Biosphere reserve and The Ejido Conhuas. c This chart shows details of the 2,400-ha studied area. MTSE: medium tropical semi-evergreen forest; LTSE: lower tropical semi-evergreen forest; and MSFF: mixed seasonally flooded forest. Filled circles in c) show sampled plots.
dominates the region. Mean annual precipitation is 1,076 mm and mean temperature is 22.5°C. Abundant karst outcroppings characterize the shallow soils of the Calakmul region, provoking low water availability (Martínez and Galindo-Leal 2002; Pérez-Salicrup 2004).
SAMPLING DESIGN We conducted rapid field assessments (RFAs) to explore the abundance and population patterns of C. seifrizii. RFAs were conducted in the Conhuas forest reserve at random sampling points. At each point 10 50×2 m plots (0.1 ha) were sampled. We sampled 43 points for a total of 4.3 ha. At each site all C. seifrizii genets (>5 cm stem length) rooted within the plots were recorded. For each sampling point, we registered forest and soil type. For each genet the number of ramets was recorded; for each ramet, stem length, number of leaves, sex, number of old and new infructescences and fruits (hereafter often called fruits or seeds) were also registered. C. seifrizii bears infructescences for 12–20 months and differences in coloration allow easy differentiation
between old and new infructescences. Thus, we registered the infructescences and fruits produced in the 2007 and 2008 seasons.
DATA ANALYSIS Population patterns of C. seifrizii were evaluated through a population structure analysis at the genet level. We classified palms according to the number and size of living ramets present for each genet: seedlings (ramets 10 cm stem length), and adults (varying in number of ramets: Ad1 = 2–3, Ad2 = 3–5, Ad3 = 6–9, Ad4 ≥10 ramets). To evaluate the production potential of C. seifrizii in the study area, we estimated the number of harvestable leaves and seeds produced per hectare by adults. Two types of generalized linear model (GLM) were conducted: 1) one-way GLM for assessing differences in density per hectare among forest and soil types, and 2) two-way GLM to assess differences in population structure, number of leaves, and number of seeds among: i) forest type, ii) genet size, and iii) their interaction. GLMs
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were performed in R version 2.10.0 (Crawley 2007; R Development Core Team 2009). To evaluate the variation of seed production between years, we correlated the seed production from 2007 and 2008. We analyzed this relationship through a regression using count data and a GLM (Crawley 2007). To evaluate the economic potential of C. seifrizii, we estimated the income in U.S. dollars per hectare, which would result from the collection and trade of both seeds and leaves. We used different harvest intensities reported in previous palm studies and used prices (in USD) for the area in 2009 (Bernal 1998; Endress et al. 2006; Hernández-Barrios 2008; Lopez-Toledo 2003; Martínez-Ramos et al. 2009; Ratsirarson et al. 1996). Finally, to estimate the importance of xate in the current local economy we conducted interviews with the head-of-household for each of the 102 families in the community. We applied open-ended questions to determine their annual income generated by economic activities, including xate seeds collection, during 2007. Based on annual income and the percentage obtained by xate trading, each household was classified as i) high (>50%), ii) medium (
