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Most residents of the Willamette Valley do not recognize ponderosa (yellow) pine (Pinus ponderosa) as a natural part of their landscape. Most assume that the scattered ponderosa pine visible in the Valley were grown from seed collected east of the Cascade Mountains.

In fact, some standard references (e.g., Franklin and Dyrness 1973) do not mention ponderosa pine occurring in the Valley north of Eugene. Thus, many are surprised to learn that ponderosa pine has been growing throughout the Willamette Valley for several thousand years (Pearl 1999) and that it is a genetic race distinct from the ponderosa pine found east of the Cascade Mountains (Gooding 1998).

The following is an abstract from a paper being submitted for publication on the ecological history of ponderosa pine in the Willamette Valley.

Prehistoric information.

Sediment cores from Lake Labish and Onion Flats, two neighboring deep peaty deposits in the central Willamette Valley near Salem (Hansen 1947) and an old ox bow near Albany (Pearl 1999) show ponderosa pine pollen rising to the current low levels about 7,000 years ago. Many of the current Willamette Valley prairie and woodland species also became common in the pollen profiles around 7,000 years ago.

Before 1850.

David Douglas describes an oak-pine savanna in the north valley near present-day Newberg in 1826 (Davies 1980) and in the foothills of the western and southern parts of the valley. Johannessen et al. (1971), using GLO survey records of 1852/4, found ponderosa pine occurring in the foothills, on the flood plain, and in riverine forests between Eugene and Halsey.

It was associated always with Oregon white oak (Quercus garryana) and sometimes with Douglas-fir (Pseudotsuga menziesii). Benner and Sedell (1997) also put a ponderosa pine, white oak type in this location.

In the hills immediately south of Eugene, Cole (1977) found ponderosa pine and white oak were common associates of Douglas-fir in 1850 on the hilltops and upper southerly slopes, where 23%-29% of the 64-70 trees per ha was ponderosa pine.

In a survey of two old forest stands south of Eugene, we found that, in 1850, the study area varied from ponderosa pine/Douglas-fir/oak savanna to open woodland to patches of closed-canopy forest. Judging by the surviving trees, the trees of the study area were generally quite young in 1850 (median age = 30 yr).

In the Calapooia basin, Boag (1992) described ponderosa pine as occurring in 1850 with white oak and Douglas-fir as trees scattered in grass.

Today.

A comparison of the historical distribution of ponderosa pine with the current distribution shows some pine present in most of historic locations except the west side of the Valley on the Coast Range foothills.

Since 1850, much ponderosa pine has been lost to harvesting, conversion to other land uses and forest succession. The exclusion of fire from the Valley has allowed the native incense cedar, grand fir, and Douglas-fir to grow up through and shade out the white oak while preventing regeneration of ponderosa pine. Thus, the ponderosa pine will be lost too. Figure 1 shows this species shift at one site south of Eugene.

Literature Cited

Benner, P. A., and J. R. Sedell. 1997. Upper Willamette River landscape: a historical perspective. Pages 23-47 In A. Laenen and D.A. Dunnette (editors) River Quality B Dynamics and Restoration. Lewis Publishers, New York, New York.

Boag, P. G. 1992. Environment and Experience: Settlement Culture in Nineteenth-Century Oregon. University of California Press, Berkeley.

Cole, D. 1977. Ecosystem dynamics in the coniferous forest of the Willamette Valley, Oregon, USA. Journal of Biogeography 4: 181-192.

Davies, J. 1980. Douglas of the Forests. University of Washington Press, Seattle..

Franklin, J. F., and C. T. Dyrness. 1973. Natural Vegetation of Oregon and Washington. USDA Forest Service General Technical Report GTR-PNW-8.

Gooding, G. D. 1998. Genetic variation and mating systems of ponderosa pine in the Willamette Valley of Oregon. Oregon State University, Corvallis. M.S. Thesis.

Hansen, H. P. 1947. Post-glacial succession, climate, and chronology in the Pacific Northwest. Transactions of the American Philosophical Society, Vol. 37, Philadelphia, Pennsylvania.

Johannessen, C. L., W. A. Davenport, A. Millet, and S. McWilliams. 1971. The vegetation of the Willamette Valley. Annals of the Association of American Geographers 61: 286-302.

Pearl, C. A. 1999. Holocene environmental history of the Willamette Valley, Oregon: insights from an 11,000-year record from Beaver Lake. M.S. Thesis. University of Oregon, Eugene.

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