The species richness of tropical dry forests is heterogeneous. To prevent species exploitation, a 3 km barrier was constructed within the tropical dry forest of the RAMSAR site in 1991. Theoretically, the area inside the fence should be the best preserved, with a greater number of species expected. To determine whether the fence influenced woody species richness, 20 transects (0.01 ha each) were established on both sides of the fence. Woody species with a diameter at breast height (DBH) ≥ 1 cm were recorded. Non-parametric estimators, such as sampling effort, bias, precision, accuracy, and the U Mann-Whitney test, were used for data analysis. A total of 77 and 80 species were quantified inside and outside the barrier, respectively. The most species-rich plant families were Fabaceae, Euphorbiaceae, Cactaceae, Rubiaceae, and Burseraceae. Chao 1 and ACE estimators most closely approximated the actual observed species value, with a sampling effort exceeding 92%. Jackknife 1, Chao 1, Chao 2, and ICE showed the least bias, with higher precision and accuracy. The U Mann-Whitney test revealed no significant differences in species richness between the sampled sites inside and outside the fence.

 

Key words: Bias, precision and accuracy, conservation fencing, natural protected areas, non-parametric estimators, sampling effort.