Narrow Results

Using the 22” isochronous cyclotron at the University of Chile, we have performed PIXE analyses on a group of samples collected from trees of metropolitan parks in Santiago. Dendrochronology was performed on each sample, which was then sectioned for the PIXE and other analyses, neutron activation and electro-chemistry. Available samples are trunk sections or cores obtained by the use of a 4.0 mm stainless steel incremental corer. We took three cores from each tree with permission of the municipalities. For the PIXE we use infinitely thick targets, as wood slabs taken along the trunk radius, and thin targets obtained by acid digestion of wood pieces and deposition on Kapton foils. Self supporting thick targets were placed directly in the PIXE chamber in a position so as to allow the irradiation of a specific annual ring. Potassium and Calcium appear as the most abundant elements in wood Other elements such as S, Cu, Zn, As, Br and Pb were detected in amounts above the natural background in wood, and can be attributed to environmental contamination. The K/Ca ratios appear to be different for each species of tree, and seem to be related to the physico-chemical properties of wood. Preliminary results show important amounts of As and Cu (supposedly from mining origin) with increasing presence in the recent years. Pb and Zn (supposedly from vehicle origin) are also higher in recent years.

An increase in world population and per capita income has generated unprecedented demands for fiber-based products. Consequently, wood production from timber-producing countries of the Pacific Rim has dramatically increased in recent years. Several countries in Southeast Asia have vast timber resources, primarily from the Dipterocarp forests which reach optimum condition in the evergreen rainforests of Peninsular Malaysia, Sumatra, Borneo, and the Philippines. At the same time, harvesting intensity has caused considerable degradation of the environment and depletion of forest resources, to such an extent that the problems are of great concern to many people. This paper discusses the forest resources of the Pacific Rim as they affect international trade. Indonesia is now the largest timber producer in the region; therefore, special emphasis is placed on the development of its forest products industries and the impact of environmental issues on forest conservation and management. Because the bulk of tropical timbers comes from Dipterocarp ecosystems, which also contain most of the presently underutilized species, their known wood properties and utilization potential are described. Alternative markets for wood use and new technologies to improve the effective utilization of wood are presented.

Sapotaceae, with more than 1,100 species belonging to about 50 genera, constitutes one of the largest families after Dipterocarpaceae. This study, based upon 317 sapotaceous wood samples from 28 genera and 181 species, suggests that four groups of Sapotaceae be introduced in the timber trade: nyatoh, bitis, yellow nyatoh, and NN (no name).