According to the 1936 State of Oregon Forest Type Map54 which predates extensive logging activities, nearly half the entire John Day Province was covered by pine, fir, and mixed pine–fir forests. About 40% was nonforested with primarily sagebrush-grassland in lower elevations. A surprisingly small proportion of the province, probably less than 10%, was occupied by stands of western juniper during that era. The lack of western juniper is particularly noticeable in the John Day River drainage where only scattered stands existed in the late 1930s. The upper Crooked River drainage east of Paulina also had only scattered stands of juniper.
In the southwest part of John Day Province in the vicinity of Prineville, juniper stands occupied a high proportion of the landscape. They extended east up the Crooked River to about Paulina. Preponderance of juniper around Prineville and lower Crooked River in John Day Province likely is due to the huge seed source provided by junipers that blanketed the nearby pumice-soil area (Mazama Province) from Redmond to Bend and east to about Hampton. Unpublished field studies of juniper stand structure and age classes on these pumice soils helped formulate the concept that western juniper is a climax species on pumice soils in this particular area. Growth-ring counts of huge junipers, some about 3 feet in diameter and most of which were hollow, indicated such trees were hundreds of years old. All age classes were represented in the stand, which indicates the likelihood of stand perpetuation over time, i.e., climax species.40
In the 1960s, Larry Haverfield, an SCS range conservationist, and Bill Anderson observed that the stand of juniper north of the mainstem John Day River was increasing rapidly over the landscape at that time. Likely it had originated from the stand of old juniper growing on rocky ridges several miles to the north. In this study, growth rings on all trees along a transect from the river north to the forest boundary, which was essentially the top of the main ridge, showed increasing age classes from the river to the ridgetop. The study also showed that this expansion of junipers had begun about the early 1900s. The very old juniper, the seedstock, grew on rocky ridgetops where they likely were protected somewhat from wildfire because of lack of surface fuel.
The spread of juniper in the mainstem John Day River valley near Dayville also was documented by a sequence of photos spanning several decades. This set of photos has been used to illustrate the juniper problem in John Day Province. Bill Farrell, then Grant County Extension agent, obtained the first old photo, which was taken in 1920, from a local person. He and E. W. Anderson, then range conservationist for Soil Conservation Service, located the approximate point from which the original photo was taken, and they took photos in 1945, 1956, and 1965 (Fig. 27-a - 27-d).
Figure 27-s: This photo and the three following, taken over a 45-year period, document the spread of western juniper in the mainstream John Day River valley near Dayville. This photo was taken in 1920 by a local person.
Figure 27-b: Taken in 1945 by E.W. Anderson and W. Farrell; the latter was the Grant County Extension agent at that time
Figure 27-c: Taken in 1956 by E.W. Anderson and W. Farrell
Figure 27-d: Taken in 1965 by E.W. Anderson and W. Farrell
The major increase of western juniper in John Day Province has been on lower-elevation soils, such as Tub and Simas, that are geomorphically related to the clayey ancient sediments of the Clarno Formation. One explanation for this phenomenon is that western juniper has an affinity for calcium; the clayey ancient sediments usually are calcareous.
The affinity of western juniper for calcium can be demonstrated by measuring the pH of litter and surface soils under the canopy of a large juniper and then comparing it with the pH of surface soil material away from the juniper canopy. The pH is higher under the canopy, apparently because juniper roots extract calcium from the soil in a very wide radius from each tree and subsequent leaf-fall deposits calcium on the surface under the tree.
The calcareousness of soils formed in ancient sediments of John Day Province can be demonstrated by dropping some diluted hydrochloric acid on a bare, dry surface of Tub or Simas soil in summer after surface-soil moisture has evaporated. The soil surface will effervesce.
These are basic ecological relationships that augment the more common, but only partial, explanation for the spread of juniper, which is that too much fire control has been practiced over the years. Prolonged grazing which severely uses herbaceous ground cover, reducing wildfire’s ability to travel, likely is a significant factor in this complex biological equation. As juniper increase in density, thereby totally dominating the biological situation, solving these problems becomes more difficult and expensive.
Both basaltic and rhyolitic igneous formations are in John Day Province; basalt is by far the more prominent. Rhyolite is light in color, even pinkish; basalt is dark in color. Chemically, rhyolite is acidic; basalt is basic. It is not known whether the chemistry of soils formed in each of these materials is ecologically significant. However, casual observation not supported by data indicates there might be an ecological significance. For example, observations of soils formed in rhyolite indicate that they tend to be more clayey than soils formed in basaltic materials. Also, Idaho fescue seems to be better adapted to clayey rhyolitic soils than is bluebunch wheatgrass, provided of course that the effective environment of the site is suitable for growth of Idaho fescue.
In northeastern Jefferson County south of Ashwood is a large area of rhyolitic parent material known as Blizzard Ridge. The Prag soil series formed in these rhyolitic parent materials.62 In July 1959 the extensive rhyolitic area on Blizzard Ridge contained no juniper; however, on the adjacent hilly ancient sediments—calcareous Tub and Simas soils—juniper were profuse. Prag, Tub, and Simas series all are clayey soils.
Since the affinity of western juniper for calcium in the soil has been verified, the question now is whether the absence of western juniper on soils derived from rhyolitic parent materials is due to the acidic nature of rhyolite.
Another example of how different plant communities might be related to rhyolitic and basalt parent materials occurs near Mitchell in Wheeler County. White Butte, which is likely a rhyolitic volcanic cone, and Black Butte, which is likely a basaltic volcanic cone, produce different plant communities. Western juniper is prominent on Black Butte but not on White Butte.
Soil–plant relationship studies of ecological sites in John Day Province indicate that nearly all nonforested sites originally were natural shrub–grasslands, i.e., having 10% or more canopy cover of shrubs. However, steep north-facing slopes in John Day Province nonforested areas likely are natural grasslands on which Idaho fescue very strongly dominated the plant community. A variety of shrub species occur sparsely (less than 10% canopy cover collectively) on these steep north-facing sites in spite of the strong competition from dense Idaho fescue. These shrubs include bitterbrush, wax currant, rose, low Oregon-grape, buckwheats, green rabbitbrush, and common snowberry.
On lower-elevation, more arid natural shrub–grassland sites in John Day Province, the canopy cover of shrubs includes big sagebrush, bitterbrush, gray horsebrush, gray and green rabbitbrushes, buckwheats, wax currant, low sagebrush, and broom snakeweed. On higher-elevation, more moist natural shrub-grassland sites, the shrub component additionally includes such species as rose, low Oregon-grape, common snowberry, serviceberry, and green rabbitbrush.
The natural shrub–grassland site locally called scabland, which is mainly on very shallow, very stony ridgetops, occurs in John Day Province as well as in Columbia Basin and Blue Mountain provinces. The major shrub on scabland in John Day Province is low sagebrush but is rigid sagebrush on scabland in Columbia Basin and Blue Mountain provinces. On some plateaus and ridges in John Day Province is a unique land pattern locally called biscuit scabland. For an explanation of the origin of this land pattern, refer to the section on Columbia Basin Ecological Province; there, biscuit scabland is prominent and widespread.
The widespread occurrence of basin wildrye on small colluvial fans, terraces, and pockets of colluvial soil scattered over the landscape in hilly ancient sediments is typical for John Day Province. Erosion and local deposition of fine materials creates these pockets or stringers of deeper colluvial soils where basin wildrye becomes established (Fig. 28). Basin wildrye also dominates on floodplains and fans along intermittent and small perennial streams. Prominent perennial streams, such as Bear Creek near Seneca, typically produce wet-meadow vegetation, sometimes interspersed with patches of dry-meadow vegetation on high spots, and usually with a dry-meadow fringe around the perimeter where the meadow adjoins the uplands.
Figure 28: A managed natural shrub-grassland on which basin wildrye (the light-color vegetation) is growing in colluvial soils on uplands near Waterman Flat, Wheeler Country, in John Day Province, Oregon
Natural stands of coniferous trees occupied about half the area in John Day Province in 1936. These stands constituted five generalized plant communities which have management implications.
1. Western juniper with an understory of bunchgrasses such as bluebunch wheatgrass, Idaho fescue, Sandberg bluegrass, Thurber needlegrass, basin wildrye; a wide variety of perennial forbs; shrubs such as bitterbrush, big sagebrush, gray horsebrush, and green rabbitbrush; and juniper reproduction.
2. Ponderosa pine with an understory of bunchgrasses such as Idaho fescue, bluebunch wheatgrass, Wheeler bluegrass, Thurber needlegrass, prairie junegrass, and sedge; many perennial forbs; a wide variety of shrubs such as bitterbrush, mountain and common snowberry, wax currant, low Oregon-grape, curlleaf mountain-mahogany, and wax currant; an occasional western juniper; and pine reproduction.
3. Ponderosa pine with an understory dominated by sedge and a wide variety of grasses such as big, Kentucky, Wheeler, and Sandberg bluegrasses, Idaho fescue, mountain brome, prairie junegrass, pinegrass; many perennial forbs; shrubs such as bitterbrush, mountain and common snowberry, snowbrush, willow, and wax currant; and pine reproduction.
4. Ponderosa pine/Douglas-fir/grand fir with a midstory of saplings and pole-size trees; a dense cover of sedge with some big, Kentucky, Sandberg, and Wheeler bluegrasses, pinegrass, prairie junegrass, and other bunchgrasses; shade-tolerant forbs such as arnica, woollyweed, green lupine, pearleverlasting, strawberry; shrubs such as bitterbrush, common snowberry, spirea, willow, and low Oregon-grape; and reproduction of all tree species.
5. Douglas-fir/grand fir/ponderosa pine, usually on north-facing slopes above 3,500 feet elevation, with abundant saplings and pole-size trees; a sparse understory of shade-tolerant grasses, forbs, and shrubs; and reproduction of all tree species although ponderosa pine is sparse.
The different kinds of soil that help differentiate John Day Province forested areas from Blue Mountain Province forested areas are reflected in significant differences in site-specific plant communities. For example, John Day Province has natural juniper stands but Blue Mountain Province does not. Ponderosa pine/bunchgrass ecological sites are in both provinces, and based on superficial observation they resemble each other—pine trees, grasses, forbs, and shrubs. However, field studies of this ecological site in both provinces reveal significant differences in the species that constitute the plant community of the site. In John Day Province, the following species regularly occur on the pine–bunchgrass site but are rarely, if ever, found on this site in Blue Mountain Province: Wheeler bluegrass, Thurber needlegrass, mountain snowberry, curlleaf mahogany, green rabbitbrush, big sagebrush, and western juniper. On the other hand, the following species regularly occur on the pine–bunchgrass site in Blue Mountain Province but are rarely, if ever, found on this site in John Day Province: onespike oatgrass, threadleaf sedge, huckleberry, mockorange, and herbaceous sage.
Even greater differences occur on the ponderosa pine–sedge ecological site in each of these provinces. For example: the following species regularly occur on this site in John Day Province but rarely, if ever, occur on this site in Blue Mountain Province: basin wildrye, Wheeler bluegrass, mountain snowberry, curlleaf mahogany, green rabbitbrush, big sagebrush, and western juniper. The following species regularly occur in Blue Mountain Province on this site but rarely, if ever, occur on this site in John Day Province: slender wheatgrass, timber oatgrass, western fescue, Columbia needlegrass, threadleaf sedge, blue wildrye, slender hairgrass, deerbrush, elderberry, spirea, huckleberry, ninebark, serviceberry, dogbane, syringa, chokecherry, bittercherry, oceanspray, bearberry, and herbaceous sage.
Generally, John Day Province pine/fir plant communities consist of fewer species than those in Blue Mountain Province. This might be related to the soils and climate of the two provinces. Average precipitation for John Day Province is significantly lower than for Blue Mountain Province, and the percentage of annual precipitation that falls during the growing season of perennial herbaceous species also is lower (see the section on climate in each province description).
It also should be noted that the herbaceous understory of pine/sedge and pine/Douglas-fir/sedge ecological sites in John Day Province is strongly dominated by sedge, whereas the herbaceous understory of equivalent ecological sites in Blue Mountain Province is strongly dominated by pinegrass. This situation also might be related to soils and climates of the two provinces.