Four large provenance studies of ponderosa pine were established between 1911 and 1927. A study at Flagstaff, Arizona by Gus Pierson tested 26 provenances (1912-17), another at Priest River, Idaho by Walter Kempf tested 22 (1911-17), one in Oregon-Washington by Thornton Munger (1926) tested 10 provenances on six study sites, and one in New Zealand by A.M. Moore tested 13 (1927) at a single site. Eighty-year data have been taken on the first two studies, 60-year data on the third, and 25-year data is available on the fourth.
The studies are remarkable in their good sampling of nearly the entire species range, but the success of establishing equal provenance representation was not as good. However, the outcome of the four long-term studies gives a reasonably clear general picture of some limits of usefulness of seed movements to improve growth. For example, all but three provenances from near the study site of the Idaho study had less volume at 80 years than at 50 years. For the Arizona study at 80 years, only those provenances from Arizona, New Mexico, Utah and Colorado survived. Needle diseases decimated the New Zealand study soon after its 25-year report.
The Oregon-Washington study, known as the Ponderosa Pine Regional Races Study, has a complex pattern of provenance (race) responses at 60 years. Between 50 and 60 years, yields changed from being clearly related to growth rate, to being clearly related to survival. Because three of the sites are in Douglas-fir forests, too mesic for Ponderosa Pine to occur naturally, the pattern on them has been that the provenances from west of the Cascades have shown far the best height and volume increment.
This race study of the USDA-Forest Service Experiment Station has special significance to the Willamette Valley Ponderosa Pine Conservation Association in providing some actual data in how widely Willamette race may be adapted outside the Willamette Valley. The five remaining sites of the study provide greatly different responses that may indicate where it might be used, and where it should not. The study tested ten regional races of Ponderosa pine on six sites. Races were from around the periphery of its range, three west of the Cascade summit, and three east of it.
The Willamette race originated at 100 feet elevation near Peoria, OR . The Willamette Valley study site was at 900 feet on a south slope seen looking north from Corvallis (on the McDonald Forest). On this site it was the tallest of the 10 races until 1943, when this slender race was largely borne down by a record ice storm. At the Bend site, the Willamette race is clearly the tallest and best yielding of the 10 races. Likewise, at the Whitman site in the Blue Mountains near John Day, OR, it is the tallest, and best yielding, but is being increasingly challenged by a race from 4600’ in the Bitterroot Mountains of western Montana. On Pack Forest (U of W) west of the Cascade Mountains at 1,150’, it ranks only 5th in yield, and has suffered from snow and ice break. At Wind River site (Forest Service) just north of the Columbia Gorge, though second in height and yield there, it is being rapidly decimated along with the other races by Armallaria melia. What this tells is that even in the Willamette Valley, it had best be used near the Valley floor and not subjected to heavy snows and ice of the surrounding uplands. It may be moderately tolerant of the low temperatures and the droughts east of the Cascades, but its limits beyond this study are not known. Also it can be decimated by Armallaria melia.
The other nine regional races express an equally strange array of traits from site to site in this study. The stocky Eldorado race from Placerville, CA was fastest-growing on West-side sites, but failed from cold on sites east of the Cacades. The bushy Steilacoom race, gradually overtook, and is now the highest yielding at McDonald site, but also failed at Wind River, Pack, Bend and Whitman sites. Rogue race, from east of Crater Lake, is average except for being top preformer in the cold-air drainage of Wind River site. Lassen race, from the rain-shadow formed by Mt. Lassen, is generally slow growing, except at the rain-shadow of Bend site where it rates second. Deschutes race, from downtown Bend area, has good survival at Bend and Whitman sites, but is slow-growing and low-yielding even there. Harney race, from the Black Hills SD, is primarily 2-needled and slowest growing of the ten at all sites. Coconino, AZ race is surprisingly third best yielding at Pack site, but generally slow growing elsewhere and poor surviving on other sites. Carson NM race is slow growing and poor surviving at all sites. The latter three races are obvious failures on these Oregon and Washington test sites.
Up to 30 years, despite seedling losses to animals and drought, sufficient numbers survived to have adequately stocked most racial plots at all sites. But while yields up to 40 years were related to growth rates of the races, between 50- and 60- years, yields became primarily related to their survival. By 76 years, this was fairly obvious at the Bend site. The Whitman site has much the same pattern as the Bend site. The Wind River site is now virtually decimated. McDonald site is rapidly deteriorating, and Pack site has only one promising race remaining. It seems young provenances attempt to grow at their inherent growth rates whenever conditions are favorable, but that trees age and weaken like humans.