Are Mayan community forest reserves effective in fulfilling people's needs and preserving tree species?

Mayan community forest reserves (MCFR) play an important role in agricultural landscapes in Mexico, as they provide forest products and a broad variety of benefits that contribute to improving local people's livelihoods. Nevertheless, academia has generally considered conservation and use of forest resources to be incompatible. We describe the spatial configuration of MCFR, evaluate floristic and structural characteristics of woody vegetation present in selected reserves, and identify social norms that govern use and conservation of MCFR. These reserves largely consist of mature vegetation (80% of total cover); their plant structure is similar to that of the surrounding tropical sub-deciduous forest; and they house a large number of endemic species. The MCFR studied contain a total of 146 tree species and cover 11% of the study area, which includes at least 140 villages in the north-central part of the Yucatan Peninsula. These reserves are collectively managed and conserved by Mayan peasants in the interest of the common good. The communities in our study area combine conservation and use of forest resources, and we recommend that in public policy, government agencies and NGOs incorporate MCFR as a model of biological conservation and sustainable natural resource use, taking into account traditional knowledge and local norms that allow these reserves to function in a sustainable manner.

Silvopastoral systems of the Chol Mayan ethnic group in southern Mexico: Strategies with a traditional basis.

Silvopastoral systems combine trees and/or shrubs with grazing cattle. In the municipality of Salto de Agua, Chiapas, Mexico, some indigenous communities have developed silvopastoral systems based on their traditional knowledge regarding use of local natural resources. Through analysis of classification based on the composition of tree vegetation, two groups of grazing units were identified in the study area. Different attributes of tree and herbaceous vegetation, as well as of agricultural management and production, were compared between the two groups. Results indicate that at least two strategies of silvopastoral management exist. The first - LTD - is characterized by an average density of 22 adult trees ha(-1) in grazing units with an average surface area of 22.4 ha. The second - HTD - has an average of 54.4 trees ha(-1) in grazing units with an average surface area of 12.2 ha. Average richness per grazing unit for the LTD strategy was 7.2 species, and for HTD strategy it was 12.7 species. Average basal area for LTD was 1.7 m2 ha(-1), and for HTD 3.8 m2 ha(-1). Finally, the average level of fixed carbon for LTD was 2.12 mg ha(-1), and for HTD 4.89 mg ha(-1). For all variables, there was a significant difference between the two strategies. In addition, both strategies differ in prairie management. In the HTD strategy, growers spare their preferred spontaneously growing tree species by clearing around them. Many of these species, particularly those harvested for timber, belong to the original vegetation. In these prairies, average coverage of native grasses (60.8 ± 7.85) was significantly greater than in the LTD strategy (38.4 ± 11.32), and neither fertilizers nor fire are used to maintain or improve the pastures; by contrast, in HTD prairies, introduced grasses, principally Cynodon plectostachyus, have a higher average coverage (43.4 ± 13.75) than in the LTD prairies (17.08 ± 9.02). Regardless of the differences in composition of tree and herbaceous vegetation, in both types of grazing units a similar animal load is maintained. Many attributes of these silvopastoral strategies - based on traditional technology of the Chol farmers of the Tulija River Valley - concord with sustainable agriculture and provide a wide variety of services to the farmer and the environment. Diffusion of this technology in areas similar to that of this region could have a positive impact on the economy of conventional cattle raisers while generating environmental services.

Tropical secondary forest management influences frugivorous bat composition, abundance and fruit consumption in Chiapas, Mexico.

Most studies on frugivorous bat assemblages in secondary forests have concentrated on differences among successional stages, and have disregarded the effect of forest management. Secondary forest management practices alter the vegetation structure and fruit availability, important factors associated with differences in frugivorous bat assemblage structure, and fruit consumption and can therefore modify forest succession. Our objective was to elucidate factors (forest structural variables and fruit availability) determining bat diversity, abundance, composition and species-specific abundance of bats in (i) secondary forests managed by Lacandon farmers dominated by Ochroma pyramidale, in (ii) secondary forests without management, and in (iii) mature rain forests in Chiapas, Southern Mexico. Frugivorous bat species diversity (Shannon H') was similar between forest types. However, bat abundance was highest in rain forest and O. pyramidale forests. Bat species composition was different among forest types with more Carollia sowelli and Sturnira lilium captures in O. pyramidale forests. Overall, bat fruit consumption was dominated by early-successional shrubs, highest late-successional fruit consumption was found in rain forests and more bats consumed early-successional shrub fruits in O. pyramidale forests. Ochroma pyramidale forests presented a higher canopy openness, tree height, lower tree density and diversity of fruit than secondary forests. Tree density and canopy openness were negatively correlated with bat species diversity and bat abundance, but bat abundance increased with fruit abundance and tree height. Hence, secondary forest management alters forests' structural characteristics and resource availability, and shapes the frugivorous bat community structure, and thereby the fruit consumption by bats.

How predictive is traditional ecological knowledge? the case of the Lacandon Maya Fallow Enrichment System

La habilidad de predecir mediante una asociación estadística o conocimiento causal es la clave característica del conocimiento científico. Sin embargo, el poder predictivo del conocimiento ecológico tradicional basado en datos obtenidos de observaciones pocas veces ha sido evaluado o criticado. Analizamos el poder predictivo de los resultados de un estudio de caso en el manejo de acahuales (vegetación secundaria). Para este propósito aplicamos tres análisis estadísticos contrastantes; análisis de covarianza, modelación espacial descriptiva y modelo gráfico. Nuestros resultados sugieren la necesidad de contar con cierto grado de abducción o explicación a posteriori para el análisis de las observaciones derivadas de las estrategias realizadas por los indígenas. A pesar de ello pudimos reconocer el poder predictivo del conocimiento indígena a partir de una combinación de experiencia, deducción e inducción probabilística. El presente estudio de caso sugiere que el conocimiento ecológico tradicional lacandón es de utilidad para guiar los esfuerzos hacia la restauración del ecosistema selvático, particularmente con el uso de Ochroma pyramidale como agente de enriquecimiento del suelo.

The ability to predict through causal understanding or statistical association is a key feature of scientific knowledge. However, the predictive power of traditional ecological knowledge in an observational setting is rarely critically evaluated. We analyze the results of an applied case study of indigenous fallow management in the context of its predictive power. In order to do this we applied three contrasting statistical analyses; visual pattern matching, general linear modelling and graphical models. Our results suggest that a degree of abduction or a posteriori explanation is typically needed in the analysis of the observations of natural phenomena that indigenous people make. Despite this, contextually useful predictive power may be extracted from such information through a combination of experience, deduction and probabilistic induction. The present case study suggested that the traditional ecological knowledge of the Lacandon people could provide useful guidance for the restoration of ecosystem function. In particular, the results support the use of Ochroma pyramidale as a soil enriching agent.

A habilidade de predizer mediante uma associação estatística ou conhecimento causal é a clave característica do conhecimento científico. No entanto, o poder preditivo do conhecimento ecológico tradicional baseado em dados obtidos de observações poucas vezes tem sido avaliado ou criticado. Analisamos o poder preditivo dos resultados de um estudo de caso no manejo de "acahuales" (vegetação secundária). Para este propósito aplicamos três analises estatísticas contrastantes; analise de co variação, modelação espacial descritiva e modelo gráfico. Nossos resultados sugerem a necessidade de contar com certo grau de abdução ou explicação a posteriori para a análise das observações derivadas das estratégias realizadas pelos indígenas. A pesar disto podemos reconhecer o poder preditivo do conhecimento indígena a partir de uma combinação de experiência, dedução e indução probabilística. O presente estudo de caso sugere que o conhecimento ecológico tradicional lacandon é de utilidade para guiar os esforços para a restauração do ecossistema selvático, particularmente com o uso de Ochroma pyramidale como agente de enriquecimento do solo.

Caracterización del uso tradicional de la flora espontánea en la comunidad Lacandona de Lacanhá, Chiapas-México / Characterization of the traditional used spontaneous flore to the community Lacandona of Lacanhá, Chiapas, México

Entre 1993 a 1999 se realizaron herborizaciones sistemáticas en selva alta perennifolia, acahuales (comunidades secundarias) de diferentes edades y milpas pertenecientes a la comuidad de Lacanhá Chansayab, en la Selva Lacandona. Los especímenes recolectados se identificaron y procesaron como ejemplares de herbario acompañados de información sobre habitat, forma de vida y formas de aprovechamiento. Se recabó información sobre la importancia relativa de estas especies útiles en la estructura de las selvas altas y acahuales del sureste mexicano. Se registraron 485 especies de plantas vasculares, de las cuales el 73,4 por ciento (356 especies) fue reconocido y aprovechado por los lacandones. De un alto porcentaje (77 por ciento) de estas especies se obtuvieron materiales vegetales para satisfacer necesidades de autoconsumo como construcción, alimentos, leña y medicamentos; otros materiales son extraídos con fines comerciales como los requeridos para elaborar artesanías, y venta de fibra de pita y de hojas de palmas. En la estructura de la selva y acahuales destacan 124 especies utilizadas por los lacandones. El uso de estas especies a lo largo de un gradiente sucesional nos muestra el carácter persistente del aprovechamiento del recurso vegetal por esta etnia; así la riqueza de especies utilizada por lacandones se incrementa directamente con el período de descanso de la vegetación