Removal of trees infected with the Sudden Oak Death Syndrome (SOD) might be desirable because of hazard issues or utilization potential. This project was initiated to analyze the potential value of using the infected wood for value-added products and to further understand the risk of spreading the disease through disposal and utilization channels. Of the hardwood host trees known to be infected, only Lithocarpus densiflorus (tanoak) and Quercus keloggii (California black oak) have any previously demonstrated value as commercial lumber. However, if other infected species can be effectively used to produce a value added product it can help defer some of the costs of removal and disposal. In addition, if it is confirmed that other commercial lumber species are viable hosts for the disease and likely to aid in the spread of the disease then SOD has the potential to be a major threat to the forest products industry. The primary focus of this study is to evaluate the effects this disease has on the raw material properties of infected material and to evaluate disposal and utilization options. The objectives are to: 1/ survey the existing utilization markets and processing infrastructure for the host tree species, 2/ analyze the basic wood properties of the most severely infected tree species, and 3/ determine the utilization potential and best uses for infected wood.
This paper reports on the preliminary wood quality results of Quercus agrifolia (coast live oak). Physical and chemical properties of healthy (control specimens) trees were compared with early symptomatic, advanced symptomatic, and dead trees. Two different sites in Marin County were sampled. Properties measured include wood density, extractive content, and sugar analysis (total polysaccharides and degradation of cellulose and hemicellulose). Density, a benchmark property for utilization, decreased with increasing levels of disease, as much as a 20% reduction was measured in infected, dead trees but the results are confounded by the large variations of density within the species tested – coast live oak. Sapwood extractive content also followed the progression of the disease and decreased from about 10% (by mass) to 2% in the dead specimens, suggesting metabolic activity of biodeteriogens. A slight decrease in NaOH solubility with advancing levels of disease also supports the observation of sapwood degradation. At this time, the role of secondary pathogens (hypoxylon, other decay fungi, ambrosia beetles, and bacteria) is not clear. Lignin and sugar contents, tree form and the large density variation found in infected trees preclude the use of coast live oak for lumber used. Based on the preliminary chemical analysis, this material has potential for uses as firewood, compost, hog fuel, pulp, and fuel ethanol. Further study of each of these suggested uses is needed to determine the effects of processing on the viability of the disease and the risk of spread in processed material.
Project Funded in part by USDA Forest Service-Pacific Southwest Region, Agreement # 01-CA-11272138-127
