Roy, Douglass F. 1966. Silvical characteristics of redwood (Sequoia semper- virens [D. Don] Endl.). Berkeley, Calif., Pacific SW. Forest & Range Exp. Sta. 20 pp., illus. (U.S. Forest Serv. Res. Paper PSW-28) Describes the climatic, edaphic, physiographic, and biotic habi- tat conditions of the natural range of redwood (Sequoia semper- virens [D. Don] Endl.) and how this tree reproduces, grows, and dies. 181:174.7 Sequoia sempervirens Roy, Douglass F. 1966. Silvical characteristics of redwood (Sequoia semper- virens [D. Don] Endl.). Berkeley, Calif., Pacific SW. Forest & Range Exp. Sta. 20 pp., illus. (U.S. Forest Serv. Res. Paper PSW-28) Describes the climatic, edaphic, physiographic, and biotic habi- tat conditions of the natural range of redwood (Sequoia semper- virens [D. Don] Endl.) and how this tree reproduces, grows, and dies. 181:174.7 Sequoia sempervirens Contents Page Introduction------------------------------------------------------------------------------------ 1 Habitat Conditions ---------------------------------------------------------------------------- 1 Climatic ---------------------------------------------------------------------------------- 1 Edaphic ---------------------------------------------------------------------------------- 2 Physiographic --------------------------------------------------------------------------- 2 Biotic ------------------------------------------------------------------------------------ 3 Life History ----------------------------------------------------------------------------------- 4 Seeding Habits -------------------------------------------------------------------------- 4 Vegetative Reproduction -------------------------------------------------------------- 6 Seedling Development ----------------------------------------------------------------- 7 Seasonal Growth ----------------------------------------------------------------------- 9 Sapling Stage to Maturity --------------------------------------------------------- ---- 9 Special Features ------------------------------------------------------------------------------ 12 Race and Hybrids ----------------------------------------------------------------------------- 13 Literature Cited ------------------------------------------------------------------------------- 14 Appendix -------------------------------------------------------------------------------------- 17 The Author DOUGLASS F. ROY is responsible for the Station's silvicultural studies of pines, mixed conifers, and true fir types. Native of San Francisco, he earned B.S. (1946) and M.S. (1962) degrees in for- estry at the University of California. Upon joining the U.S. Forest Service in 1946 he was assigned to the Station's research staff at Berkeley. Since 1963, he has been headquartered at Redding, California. Figure 1 . ― The natural range of redwood. he first record of redwood (Sequoia Although he did not explain the origin of the sempervirens [D. Don ] Endl.) was generic name, it seems certain that it honors the T written by Fray Juan Crespi on Tues- Cherokee Indian, Sequoyah, or George Guess. Se- day, October 10, 1769, in his diary of the Don quoyah was talented, active, and prominent in Gaspar de Portola Expedition. On that day the working for his tribe, and is best known for de- expedition traveled northwestward from a camp veloping an 83-character syllabic alphabet for the on the Pajaro River, now the boundary between Cherokees (Jepson 1910; Save-The-Redwoods Santa Cruz and Monterey Counties, into low hills, League 1935). well forested with very high trees of a red color. The natural range of redwood extends south- No one recognized these trees so they were named ward from two groves on the Checto River in the redwood (palo colorado) from their color. extreme southwest corner of Oregon to Salmon Archibald Menzies, surgeon and botanist with Creek Canyon in the Santa Lucia Mountains of the Vancouver Expedition, is credited with the southern Monterey County, California. This red- botanical discovery of redwood. He probably saw wood belt is an irregular, narrow coastal strip this tree at one or more points on the California about 450 miles long and 5 to 35 miles wide.1 It coast in 1792 or 1793, but his collection is dated has a transverse break along the headwaters of the 1794 (Jepson 1923). Mattole River in southern Humboldt County. Stephen Endlicher, the noted Hungarian bot- And south of Sonoma County, redwoods are found anist, named the genus and the species in 1847. in detached and irregular areas (fig. 1). Habitat Conditions Climatic Annual precipitation varies between 25 and The mild climate of the redwood region with 122 inches and falls mostly as winter rain, al- its equable temperatures can be classed broadly though the highest ridges sometimes are covered as superhumid or humid (Thornthwaite 1941). with snow. The distribution of precipitation at Mean annual temperatures vary between 50° and Scotia, Humboldt County, by seasons is: winter, 60° F. Differences between mean annual maxi- 55 percent; spring, 23 percent; summer, 2 per- mum and mean annual minimum temperatures cent; and autumn, 20 percent. Generally, January range from 10° to 15° F. for coastal points to 30° is the wettest month, and August is the driest F. for the eastern edge of the redwood type. Tem- (Martin and Kincer 1934). peratures rarely fall below 15° F. or climb above The frequent summer fogs which blanket the 100° F. The frost-free period lasts from 6 to 11 redwood region seem to be more important to months (Person 1937; U. S. Forest Service 1908). redwood than the amount of precipitation. Fog de- creases water loss from evaporation and trans- piration and adds to the soil moisture supply to 1 some degree. The relationship between redwood By Forest Survey definition, which classifies a forest and fog seems intimate because the natural range stand as redwood type if redwood trees comprise 20 percent of the stand, including hardwood and conifer of this tree is limited to the regions where heavy cover, the commercial forest land area in redwood summer fogs from the ocean provide a humid at- type totals 1.6 million acres. mosphere (Cooper 1917). 1 Edaphic lowest amount of soil moisture available during the year. This minimum available moisture, ex- The parent rock material of the redwood region pressed as a percentage of storage capacity, ranged is largely massive marine sandstone formed in the between 18 and 86, with 62 correlated with maxi- Tertiary and upper Mesozoic periods. Consider- mum basal area (Waring and Major 1964). able shale and lesser amounts of Mesozoic lime- stones and Franciscan slates, cherts, limestones, and sandstones also are represented, and schists are fairly common in some localities (Person 1937). Physiographic Soils vary from thin rocky loams on some of Redwood stands are largely confined to coastal the steepest slopes to deep sandy loams on flats topography between latitude 35° 41' N. and 42° and benches. Sometimes clays are close to the sur- 09' N. Much of the land configuration is charac- face and clay loams replace the more typical loams terized by irregular ridges oriented northwest to and sandy barns. One characteristic soil is mod- southeast with deep, narrow valleys between (Poli erately deep sandy loam containing a variable ad- and Baker 1954). Consequently, the principal mixture of fine to coarse rocky material, usually streams drain to the northwest. sandstone, with a clayey subsoil (Person 1937). Although this mountainous area is still develop- ing by fold-faulting (Hinds 1952), the topography Productive soils for redwood are the Hugo, is characteristic of early maturity in the fluvial ero- Josephine, Melbourne, Empire, Sites, and Larabee sion cycle. Much of the terrain is rough, steep, and series, and associated alluvial soils. The residual extremely dissected both by major streams and soils of high site quality have been derived from smaller drainages (Roy 1957). In spite of the either consolidated or soft sedimentary rocks. rugged terrain, the total relief is small for a moun- They are light grayish brown or light reddish tainous country. Only occasional peaks reach ele- brown to brown in color, and are moderately to vations of 4,000 to 4,500 feet above sea level. strongly acid (Gardner 1960; Roy 1957). Red- Redwoods grow from sea level to about 3,000 wood tolerates a soil pH between 5.0 (acid) and feet (Jepson 1910), but most are found between 7.5 (alkaline), with 6.5 as the optimum (Zinke 100 and 2,500 feet (Person 1937). The best stands 1964). Soil textures grade through loam, sandy have developed on the flats and benches along the loam, fine sandy loam, silt loam, to clay loam larger streams, on moist coastal plains, river deltas, (Gardner 1960; Roy 1957). moderate westerly slopes, and valleys opening Limits of redwood forests sometimes are de- toward the sea. Some of the flats and benches sup- termined by soil types. For example, redwood does port pure redwood stands of almost unbelievable not grow on soils having high amounts of magne- volumes (Person 1937). sium and sodium (Zinke 1964). Although the main bodies of redwood are close to the ocean, redwood does not tolerate ocean Fertility of soils under redwood stands has been winds. And considerable evidence suggests that it studied by measuring the replaceable calcium con- is sensitive to ocean salts carried inland during centration, expressed in equivalents, present in a storms (Jepson 1923). Where redwoods grow square meter to a depth of 30 cm. This measure close to the coast line,