02 – Rivas

Multi-species natural forests, representing more than 90 percent of the total forest area of the world, are a huge resource which can deliver many products and services, in addition to timber. Prominent examples of such natural ecosystems are the communal forests on the Mexican Sierra Madre Occidental, covering approximately 14 million ha. Based on evidence gathered in long-term observational studies in Durango (México), this study presents estimates of forest production in response to specific residual levels of forest density. These estimates permit an evaluation of production losses due to reduced stocking levels in the municipios: Santiago Papasquiaro, San Dímas and Pueblo Nuevo. The available observations show a linear response of forest production to forest density in the communal forests on the Mexican Sierra Madre Occidental, irrespective of site quality, species mixing effects and other variables. Potential production gains are illustrated for the Ejido San Diego de Tezains where detailed compartment data are available. The results regarding potential production gains provide a new basis for improved control of residual forest structures in the natural forests of the Sierra Madre Occidental. However, further studies are needed regarding the response to species diversity and mixing effects as well as specific site variables, as soon as such observations are available.