|Abstract or Summary
- Pacific madrone, tanoak, and California black oak are the most economically promising native California hardwoods. Volume and value data indicate upward trends in growing stock levels and prices received for their products. These trends are likely to continue. They suggest research is particularly needed for: (1) seed fall and
regeneration, (2) sprout growth and development, (3) stand growth and yield, and (k) species adaptation and strategy. Much new material in these categories is presented here. The ability to produce copious amounts of seed at frequent intervals
is a hallmark of Pacific madrone and tanoak, and only slightly less so for California black oak. Few of these seeds result in trees, but enough do so to insure continuous environmental tuning of the species. For Pacific madrone a seedbed free of an organic layer, which harbors invertebrates (slugs) and post-emergence fungi, is best for regeneration. A partially shaded environment is best for natural development of the oaks. Reversing polarity of tanoak and California
black oak acorns speeds up germination and enhances seedling survival and growth.
Fertilization with nitrogen and phosphorous significantly boosted California black oak seedling height growth, but was less effective for tanoak. In spite of irrigation, fertilization, shading, and use of containers, survival of tanoak seedlings in a plantation was only 33 percent after 4-6 years. Dieback and deformation were
rampant. Tanoak apparently cannot be established in conventional plantations. Survival of California black oak was 64 percent after 7 years and establishment in standard plantations is recommended. In clearcuttings, sprouts of these hardwood species initially number up to 150 per clump, but after 10 growing seasons decrease to less than 35. Height and crown width after 10 years is about 20 and 10 feet, respectively, with only minor differences among species. For the same timespan, sprouts in a shelterwood are about half as tall and three-fourths as wide. Based on new volume tables, cubic volume growth of thinned stands ranged from 48 to 93 cubic feet per acre per year with indications
that thinning to 100-125 square feet of basal area per acre was best. Ecologically, Pacific madrone, tanoak, and California black oak possess a host of adaptations that serve them well in severe environments. Huge numbers of seeds and sprouts insure that the species both remain in place and capture new area. Other adaptive phenomena discussed are the means taken to discourage competition beneath tree crowns, epicormic branching, the role of seed disseminators, competitiveness of sprouts, the stretched-out germination period, root-shoot
ratios, thickened rootstocks, need for multiple stems per clump, and ability to withstand high moisture stress.