Thursday, August 9, 2007 - 8:20 AMOOS 36-2: Cacti diversity in perturbed and conserved sites of a tropical Mexican dry forest
Luis A. Arias-Medellin and Cristina Martinez-Garza. Universidad Autonoma del Estado de Morelos
To plan future restoration projects, we evaluate cacti diversity in three perturbed and three conserved sites (0.25 ha each one) in the dry forest of Sierra de Huautla, Morelos. In these sites all cacti were tagged, measured (DBH and height for trees and shrubs and cover for prostrate cacti) and identified. In perturbed sites we found a total of seven species (four genus) and 359 individuals. Opuntia velutina (80.22 ± 65.9 cm height) was the most abundant (116 individuals) followed by Opuntia puberula (95 individuals; 0.30 ± 0.43 m2 cover). In conserved sites we found five species (four genus) and 238 individuals: Pachycereus grandis was the most abundant (214 individuals; 4.76 ± 2.95 m height, 17.52 ± 4.3 cm DBH) followed by Opuntia puberula (16 individuals; 0.18 ± 0.19 m2 cover). Besides, we recorded 68 individuals of Coryphantha elephantidens, a threatened species, in perturbed sites and only 4 individuals in conserved ones. The richness between sites was similar (t = 2.00, P> 0.05) while diversity was significantly higher in perturbed sites (Shannon diversity, t = 5.65, P < 0.01; evenness t = 5.49, P <0.01; Simpson diversity, t = 5.65, P<0.01). Perturbation seems to favor Opuntia velutina and Coryphantha elephantidens, and negatively affects Pachycereus grandis probably because of lower tree cover and higher light levels in the secondary forest. We suggest planting Pachycereus grandis in perturbed sites to fully restore cacti diversity; this will attract frugivorous birds and later increase plant diversity through seed rain.