José Luis Martínez-Sánchez

Is there a relationship between floristic diversity and carbon stocks in tropical vegetation in Mexico

Tropical vegetation plays an important role in the terrestrial carbon stocks, and Mexico has a considerable amount of this vegetation that may store a large amount of carbon. However, an important variable of vegetation is its floristic diversity. Floristic diversity influences in a great extent the biomass of an ecosystem and hence carbon stocks. The purpose of this study was to determine whether there is a relationship between floristic diversity and carbon stocks in the case of tropical vegetation in Mexico.

Light-related variation in sapling architecture of three shade-tolerant tree species of the Mexican rain forest

Se analizo la arquitectura de la copa de tres especies tolerantes a la sombra (dos del sotobosque y una del dosel medio) en relacion con el ambiente luminico del sotobosque de la selva. El objetivo fue examinar el grado de variacion que presenta la arquitectura de la copa de especies tolerantes a la sombra. Para esto, se midieron 13 variables arquitecturales en 265 arboles juveniles (50-300 cm de altura) distribuidos desde sitios de selva madura hasta claros de diversos tamanos, en la selva humeda tropical de Los Tuxtlas, Mexico. El analisis mostro que las tres especies cambian la arquitectura de su copa a medida que aumenta la disponibilidad de luz, pero de diferente forma. Ninguna especie presento el tipico modelo de copa plana esperado para las especies tolerantes a la sombra. Las dos especies del sotobosque tendieron a adoptar una copa intermedia entre plana y alargada, mientras que la especie del dosel medio, tendio hacia una copa alargada. El area horizontal de la copa se mostro como la variable mas relacionada con la luz y altura del arbol. Se concluye que a pesar de ser especies tolerantes a la sombra, aprovechan los ambientes mas luminosos para su desarrollo. La arquitectura de copa de las especies tolerantes a la sombra no es tan rigida como se creia en un principio

Relationship between Structural Diversity and Carbon Stocks in Humid and Sub-Humid Tropical Forest of Mexico

ABSTRACT Two structural-diversity and two biodiversity indexes and carbon stocks were determined at eight humid and sub-humid tropical forest sites 20–120 years old in southeastern Mexico. All trees >10 cm at diameter breast height were measured and species identified in 131 randomly located plots. The number of species (S), Shannon (H′), biomass-species (BS) and abundance-biomass-species (ABS) indexes were related to Mg C ha-1 and the age of the sites. Values were: S, 27–109; H′, 3.9–5.31; BS, 7.39–16.0; ABS, 9.87–18.2; Mg C ha-1, 39.7–130.7. The relationships between BS and ABS to carbon and the site age were linear and positive, showing that stand structure directly influenced carbon storage. The relationship between site age and carbon was remarkably high (R2 = 0.79). Humid forests showed higher values of carbon than sub-humid forests (104.4 vs. 70.6, t = 2.07, p = 0.04) but their structural diversity was similar (BS, 11.25 vs. 8.3, p = 0.134; ABS, 13.9 vs. 10.6, p = 0.135). It is concluded that forestry management of tree diameter may be a factor that can favor more carbon storage in secondary forest regrowth as it starts to reach maturity.