Pinus jeffreyi Grev. & Balf. Jeffrey Pine Pinaceae Pine family James L. Jenkinson Jeffrey pine (Pinus jeffreyi) was discovered in 1852 Summer nights are warmer and differences in in the Shasta Valley of California by John Jeffrey, a day-night temperatures are smaller for Jeffrey pine Scottish botanical explorer. Partly overlapping in the western Sierra Nevada and southern Califor- ponderosa pine (Pinus ponderosa) in range and su- nia than elsewhere in the range. July day-night dif- perficially resembling it, Jeffrey pine was first clas- ferences in these regions are as little as 11” C (20” sified as a variety of ponderosa pine (28,45). These F), and rarely exceed 19” C (34” F). In the Klamath western yellow pines produce wood of identical struc- Mountains and east of the Sierra-Cascade crest, July ture and quality and are closely related taxonomical- day-night differences mostly exceed 19” C (34” F), ly (10). Jeffrey pine is distinct chemically, ecological- approach 26” C (47” F) in some areas, and decrease ly, and physiologically and is readily distinguished to 13” C (24” F) only for stands at highest elevations. from ponderosa pine on the basis of bark, leader, Throughout the range, precipitation falls mostly needle, bud, and cone morphology (23). during the winter season. Mean annual rainfall averages as little as 380 to 430 mm (15 to 17 in) in Habitat places east of the Sierra-Cascade crest, is only 200 mm (8 in) for certain stands scattered along the east- Native Range ern Sierra Nevada and Virginia Range of western Nevada (3), and exceeds 1270 to 1520 mm (50 to 60 Primarily a California species, Jeffrey pine (figs. in> in parts of the western Sierra Nevada and 1,2) ranges north through the Klamath Mountains Klamath Mountains. Mean snowfall in Jeffrey pine into southwestern Oregon, across the Sierra Nevada localities typically ranges from 30 cm (12 in) or less into western Nevada, and south in the Transverse at lowest elevations in the Klamath Mountains to and Peninsular Ranges into northern Baja California well over 520 cm (204 in) at high elevations in the (10,20). This distribution is intimately linked with Sierra Nevada, particularly along the central crest. edaphic factors in the northwest portion of the range and strongly reflects climatic and elevational factors Soils and Topography in the northeast, central, and southern portions. Jeffrey pine thrives in comparatively harsh en- Perhaps one-fifth of the distribution of Jeffrey pine vironments throughout most of its range is on ultramafic soils. At middle elevations on the (1,21,24,55,58). Contrasted with ponderosa pine, Jef- western slope of the northern Sierra Nevada and in frey pine completes annual top growth sooner, enters the North Coast Range and Klamath Mountains, Jef- dormancy earlier, and requires longer cold exposure frey pine often dominates and is almost entirely for leader growth in spring (27). Because Jeffrey pine restricted to soils derived from ultramafic rocks- is especially cold hardy (21,221, tolerant of drought peridotites and their alteration products, serpen- (51,58,59), and adapted to short growing seasons, it tinites. The typical forest soils formed on such rocks competes well and typically dominates other conifers are fine, fine loamy, and clayey texture skeletal sur- on cold, xeric, and infertile sites. face soils. On these highly infertile, mostly shallow soils, Jeffrey pine descends to low elevations: 490 m Climate (1,600 R) in Butte County, 260 m (850 ft) in Hum- boldt County, 60 m (200 ft) in Del Norte County, CA, Jeffrey pine grows well in diverse temperature and 183 m (600 ft) in Douglas County, OR. The only regimes. Cold winters largely distinguish its range native Jeffrey pine in California’s South Coast Range east of the Sierra-Cascade crest from that in the grows on an isolated mass of sterile serpentine in Klamath Mountains, western Sierra Nevada, and San Benito County (19). Jeffrey pine’s innately short southern California. Most populations east of the growing season, limited nutrient and water crest are exposed to January mean minima between demands, and extensive root growth probably ensure -13” and -5” C (So and 23” F), while those in the west its presence on poor sites. and south are between -7” and 2” C (19“ and 36” F). Above 1600 m (5,250 ft) in ultramafic regions and at all elevations everywhere else within its range, Jeffrey pine grows on any well-drained forest soil, The author is Plant Physiologist, Pacific Southwest Forest and regardless of parent material. Most of the usual soils Range Experiment Station, Berkeley, CA. that carry Jeffrey pine are coarse or gravelly sandy 359 - jeffreyi Pinvs jcffrcri Gloup of stonds more thon 2 miles across x Stonds loss than 2 miles across or of unknOWn siZ0 ---- Proboble limit but no type doto c Extinct stond Stonds on ultmmofic rOit Figure l-The native range of Jeffrey pine. 360 Pinus jeffreyi soils. Locally prominent are Douglas-fir (Pseudotsugu menziesii), Port-Orford-cedar (Chamaecyparis law- soniana), ponderosa pine, sugar pine (Pinus lamber- tiana), western white pine (I? monticola), knob-cone pine (I? attenuatu), Digger pine (Z? sabinianu), and Sargent cypress (Cupressus sargentit). Above 1600 m (5,250 ft) in the Klamath Mountains, North Coast Range, and northern Sierra Nevada, Jeffrey pine shares various soils and sites with California red fir (Abies magnifica), white fir (A. concolor), sugar pine, incense-cedar, western white pine, and Sierra lodgepole pine (Pinus contorta var. murrayana). South of the Pit River in northeastern California and on the east side of the Cascade Range in south- western Oregon and northern California, Jeffrey and ponderosa pines form extensive forests and usually intermingle in both closed and open, parklike stands. Jeffrey pine forests range widely from 1520 to 2130 m (5,000 to 7,000 ft) of elevation in the northern Figure 2-A virgin Jeffrey pine forest near Half Dome, Yosemite Sierra Nevada, and from 1830 to 2900 m (6,000 to Park in the western Sierra Nevada, in 1916. National 9,500 ft) in the central and southern Sierra Nevada. Ponderosa pine, sugar pine, white fir, incense-cedar, loams or loamy coarse sands that often merge with California red fir, western white pine, lodgepole pine, rocklands. Where these soils are of recent volcanic and western juniper (Juniperus occidentalis) all mix origin (ashes, pumice, or cinders) they are Dystric or in locally, but few of them join Jeffrey pine on south Typic Xerorthents or Xeropsamments of the order slopes and granitic soils (9,44). Entisols. Jeffrey pine characteristically grows on Jeffrey pine is the dominant yellow pine in forests granitic soils in the Sierra Nevada (fig. 2). These east of the Sierra Nevada crest and in the Transverse soils extend over complex systems of branching and Peninsular Ranges into Baja California. In the ridges, ravines, and canyons at elevations ranging Sierra San Pedro Martir, it ranges from 1830 to 3050 from 1520 to 2740 m (5,000 to 9,000 ft), are usually m (6,000 to 10,000 ft) and shares the southern limits found in a humid microthermal climate, and vary of sugar pine, white fir, incense-cedar, and lodgepole from about 0.6 to 1.4 m (2 to 5 ft) deep. They are pine (10,45,52). Dystric and Typic Xerochrepts and Xerumbrepts of Jeffrey pine forests constitute one of the more un- the order Inceptisols. Volcanic soils and mud flows usual forest cover types in western North America commonly support Jeffrey pine in the northern Sier- (14). Because Jeffrey pine has wide edaphic and ra Nevada and adjacent Cascade Range. They are elevational ranges in diverse physiographic regions, extensive on gentle to steep slopes of dissected Jeffrey Pine (Society of American Foresters Type plateau-like areas at elevations up to 1830 m (6,000 247) is highly variable and adjoins or merges with ft), and most vary from 0.5 to 1 m (1.6 to 3.3 ft) deep many others: Red Fir (Type 207), White Fir (Type (31). They are Ultic, Typic, and Dystric Haploxeralfs 211), Lodgepole Pine (Type 218), Pacific Douglas-Fir of the order Alfisols. (Type 229), Port-Orford-Cedar (Type 231), Douglas- East of the Sierra Nevada crest from Lassen to Fir-Tanoak-Pacific Madrone (Type 234), Interior Alpine Counties, CA, and along the Virginia Range Ponderosa Pine (Type 2371, Western Juniper (Type of adjacent western Nevada, isolated patches of Jef- 2381, Pinyon-Juniper (Type 239), Sierra Nevada frey and ponderosa pines grow on more than 125 Mixed Conifer (Type 243), Pacific Ponderosa Pine- islands of altered andesite (3). These edaphically Douglas-Fir (Type 2441, Knob-cone Pine (Type 2481, restricted stands range in elevation from 1310 to Canyon Live Oak (Type 2491, and California Mixed 2130 m (4,300 to 7,000 ft), and many are within the Subalpine (Type 256). Associated understory species Pinyon-Juniper woodland (20). are diverse, reflecting climatic influences (14, p. 123). Associated Forest Cover Life History Incense-cedar (Libocedrus decurrens) is the most Our present understanding of Jeffrey pine’s life widespread associate of Jeffrey pine on ultramafic history is probably limited, because most studies 361 Pinus jeffreyi have concentrated on populations in northern harvest seeds by gnawing cones in the tree. Mice and California. voles efficiently gather, cache, and consume large quantities of shed seed. Reproduction and Early Growth Like seeds of most pines in temperate climates, Jeffrey pine germinates quickly the spring after Flowering and Fruiting-In California, Jeffrey seedfall. For starting new stands after harvest, how- pine flowers in June or July, depending on the ever, natural regeneration is seldom quick and never climatic region, elevation, aspect, and annual varia- reliable (fig.