"Relationship between carbon stocks and structural diversity in humid and subhumid tropical forest of Mexico\ud "

"Two structural-diversity and two biodiversity indexes and carbon stocks were determined at eight humid and sub-humid tropical forest sites between 20-120 yrs-old in southeastern Mexico. The dbh of all trees > 10 cm was measured and species were identified in 131 randomly located plots of different sizes. Results for the number of species (S), Shannon (H'), biomass-species (BS) and abundance-biomass-species\ud (ABS) indexes were related to Mg C ha-1 and the age of the sites. Values found 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 C and the age of the sites were linear and positive, showing that stand structure directly influenced carbon storage. The relationship between site age and C was remarkably high (R2 = 0.79). Humid forests showed higher values of C than the 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.