Zonation and management of mountain forests in the Sierra de Manantlán, México

Abstract

The woody species composition and the environment of secondary mixed Quercus forest in the Sierra de Manantlán, Mexico are described, based on 60 circular permanent plots of 500 m2 each, in which adult trees and saplings, as well as environmental variables (altitude, aspect, slope, physiography, litter and humus depth, grazing, erosion, canopy openness, herbaceous and shrub cover) were recorded. Using classification by TWINSPAN we identified seven oak community types, each dominated by one or two of the six oak species found. Canonical Correspondence Analysis ordered the plots mainly by differences in altitude and physiography. The six oak species were found in particular associations depending on the ecological zone where they were growing. The community dominated by Quercus castanea was found at the lowest altitudes and on gentle slopes; the Q. laurina community was found on abrupt slopes at intermediate altitudes; whereas the community dominated by Q. crassipes was found at the highest altitudes and on the flattest terrains. Based on species composition and environmental variables, the study area can be divided in at least two different management zones, where management here is considered for silvicultural purposes only. One zone with stands dominated by Q. crassipes could be managed using even-aged methods, e.g. a shelterwood cutting system. The second zone, mainly with stands dominated by Q. candicans, Q. laurina and Q. rugosa, could be managed using uneven-aged methods, e.g. a selection cutting system.