Demography of Bursera glabrifolia, a tropical tree used for folk woodcrafting in Southern Mexico: An evaluation of its management plan

Abstract

Tropical dry forest in Mesoamerica has long been disturbed by the extraction of different forest products by local inhabitants. Bursera glabrifolia (white "copalillo") is a dry tropical forest tree extensively used in several communities of the State of Oaxaca, Mexico, for the elaboration of folk-art woodcarvings called "alebrijes". Historically, the extraction of B. glabrifolia had not been regulated however, in October 2002, the first management plan for this species was implemented in San Juan Bautista Jayacatlan, based on abundance, distribution and dasonomic data. However, no demographic information is available on which to base a sounder management plan that would guarantee the ecological sustainability of this extractive activity. Thus, we studied the population dynamics of this species over a 2-year period in Jayacatlan, where no tree extraction had taken place since 1998. We used stem expansion rates and observations on survival and fecundity to build size-based population projection matrices. The projected population growth rate values (lambda) were 1.14 and 1.04 for the 2001-2002 and the 2002-2003 periods, respectively. These values suggest that the B. glabrifolia population at Jayacatlan shows a growing trend. Several harvesting scenarios were simulated to theoretically assess the impact on population dynamics of harvesting whole trees and, in particular, to ascertain whether the extraction regime recommended by the management plan (8 trees/ha/yr) is sustainable. For this purpose, we used an average population matrix where specific entries were modified to simulate different extraction levels. The results suggest that the harvesting regimes established in the management plan for B. glabrifolia are sustainable. However, resource managers should not exceed the amounts recommended by the management plan and should avoid extrapolating our results to other regions of the country where no demographic studies have been carried out. The need for long-term demographic studies and their incorporation in 'adaptive management plans' is discussed.