RESUMO
Introducción: Swietenia macrophylla King ("caoba") es la especie arbórea de mayor importancia comercial en el sureste mexicano y utilizada como guía en el manejo forestal, por lo que conocer su edad y tasas de crecimiento es fundamental para la sostenibilidad de los aprovechamientos maderables. Objetivos: Estimar laedad (E t ) a partir del método del 'tiempo de paso' (Tp) y calcular las tasas de crecimiento absoluto (TCA) y relativo (TCR) para Swietenia macrophylla en Quintana Roo, México. Métodos: Se ajustaron ecuaciones para calcular TCA y TCR con remediciones periódicas durante 15 años del diámetro normal (d) en 403 árboles de S. macrophylla en Felipe Carrillo Puerto, Quintana Roo, México; también, se determinaron el Tp y la E t para el cálculo del incremento corriente anual (ICA) e incremento medio anual (IMA), y definir así los turnos comercial y técnico. Resultados: La máxima TCR se alcanzó a los 28 cm de d (0.015 cm año-1) (aplicación de aclareos), mientras que la mayor TCA (0.69 cm año-1) y menor Tp (3.5 años) a los 55 cm de d (turno comercial). El máximo ICA al considerar la E t fue de 1.43 cm en la categoría diamétrica de 50 cm, con un IMA de 0.67 cm año-1 a una edad de 75 años, mientras que el turno técnico (ICA = IMA) se alcanzó a los 96 años (incrementos de 0.78 cm año-1). Conclusiones: A través de mediciones periódicas del diámetro normal en S. macrophylla es posible obtener su edad, además los resultados pueden ser utilizados para elaborar programas de manejo y ejecutar prácticas silvícolas que propicien el incremento diamétrico en Quintana Roo.
Introduction: Swietenia macrophylla King (Mahogany) is the most commercially important tree species in Southeastern of Mexico and is used as a guide in forest management. Therefore, knowing its age and growth rates is essential for the sustainability of timber harvest. Objective: Estimate the age (Et) from the 'step time' (Tp) method and calculate the absolute (TCA) and relative (TCR) growth rates for Swietenia macrophylla in Quintana Roo, Mexico. Methods: Equations were adjusted to calculate TCA and TCR with periodic re-measured for 15 years of the normal diameter (d) in 403 S. macrophylla trees in Felipe Carrillo Puerto, Quintana Roo, Mexico. Tp and Et were determined for the calculation of the annual current increase (ICA) and average annual increase (IMA), to define the commercial and technical shifts. Results: The maximum TCR was reached at 28 cm of d (0.015 cm year-1) (thinning application), whereas the highest TCA (0.69 cm year-1) and lower Tp (3.5 years) at 55 cm of d (commercial shift). The maximum ICA when considering Et was 1.43 cm in the 50 cm of diametric category with an IMA of 0.67 cm year-1 at an age of 75 years, while the technical shift (ICA = IMA) was reached at 96 years (increments of 0.78 cm year-1). Conclusions: Through periodic measurements of the normal diameter in S. macrophylla it is possible to obtain its age, these results also can be used to elaborate management programs and apply silvicultural practices that propitiate the diametric increase in Quintana Roo.
RESUMO
Half of the 10 million children who die annually in the world are from Sub-Saharan Africa (SSA). The reasons are known; but lack of will and resources avoid the development of sustainable policies. Associated factors to the high infant mortality rate (IMR) in SSA have been investigated in this research. An ecological multi-group study was designed comparing rates within SSA. The dependent variable is the IMR and health services; economic and development indicators are the independent variables. Information and data sources were WHO; World Bank; UNICEF and UNDP (1997-2007). IMR mean value is 92.2 (per 1000 live births) and a relationship with several of the factors could be observed. In the bi-variate analysis direct relationship was observed with maternal mortality rate and an inverse relationship was observed with prenatal care coverage; births assisted by skilled health personnel; gross national income per capita; per capita government expenditure on health; social security expenditure; adult literacy rate; net primary school enrolment rate; population with access to safe drinking water (in urban and rural areas) and with population with access to basic sanitation in rural areas. In the multi-variate analysis IMR had an inverse relationship with children under 5 years with diarrhoea who receive oral re-hydration; with social security expenditure as percentage of general government expenditure on health and with per capita government expenditure on health. The situation in SSA would change if their inhabitants received education and information to demand more equitable polices and better investments from their governments