September 29, 2022

San Juan Island Oak a Climatic and Edaphic Summary

The conservation of Quercus garryana in San Juan County, Washington is advanced by the consideration of the ecological components of the species distribution. The project analysis is from the iNaturalist observations in the Quercus garryana Range Project and on the San Juan Islands, Washington. The Quercus garryana Range Project is a collection of over 4,700 location specific observations. This dataset is an effort to estimate the climatic boundary of Q. garryana by the climatic values of Annual Mean Temperature (AMT) and Annual Mean Precipitation (AMP). The project compiles the AMT and AMT, the geocoordinates, soil map units, and elevation. This enables mapping of Q. garryana by soil extent, elevation, and climate. These provide a foundation for ecological understanding and to assist in the conservation and recovery.

The known spatial range of Q. garryana extends from southern California at 34.553603 -118.2388 to Campbell River on Vancouver Island at 49.978311 -125.221938. Across this range the elevation of occurrence decreases to the north. The southern California maximum occurrence is 6,734 feet is limited by the height of at the mountain range elevation. In the area of the Salish Sea the elevation range is from sea level to just over 1,700 feet with the highest observation in the San Juan group at905 feet. The San Juan Island observations may be reviewed on iNaturalist. The San Juan Islands are an EPA Level 4 Ecoregion an identifiable and unique subset of the EPA Level 3 Puget Lowlands. This considered ecological habitat area provides a rational area in which to study the ecological forces that define the Q. garryana range in the Salish basin. The San Juan Island study consist of 132 observations. These observations are biased, therefor can not be used to make statistical quantitate inference. The last observed endpoints are less then the species climatic boundaries and the current best estimated limits to guide management activities.

The dataset consists of point geocoordinates provided to iNaturalist. Elevation is estimated by the Google Earth digital terrain model. The climatic variables are the primary determinates of the species range. For the first analysis the AMT and AMP are used to estimate the climatic range by ClimateNA a streaming scale-free point climate values from the PRISM 800-meter grids. The soil data is from the SoilWeb interface to the USDA-NCSS SSURGO and SATSGO Soil Survey Products. The soil map unit is an association of the floristic community and thus it provides a spatial area of the local occurrence of the oak and a predictive area for the identification of addational or potential habitat. The primary edaphic control below the climatic control is the available soil water. This is the critical resource for summer dry season survival and the point of competition with the conifers Spittlehouse (2003). The values from Soilweb are cm of water per the top 100 cm soil profile. For the analysis this is considered an ecological index number. The product of the soil water capacity and growing season precipitation are believed to provide a higher acracy model value but are not at this time analyzed. Aspect is currently not included in the dataset. This is a needed modifying parameter as the quantity of solar input has a direct impact on the plant respiration and the water budget.

The occurrence of Q. garryana is thought to be normal relative to the climatic temperature and precipitation with a mean and variance. Across the spatial range the climatic range is truncated by the mountain height in the south and sea level in the north. The competition by conifers skew distribution in the cool wet realm. Habitat islands occur within the area of ecological exclusion. The identification of these isolated populations within the conifer competition zone are needed to confirmation an extend boundary.

San Juan Oak
Three different Q. garryana habitats are identified, marine shoreline, upland, and mesic or wetlands. This broad range of habitats is a function of genetic diversity within the taxa. The marine shoreline population is evident throughout the Salish Sea and may be a function of a saline soil and a non completive solar exposure of the water side. Examples are;
the image of observation 67730282, in the Cady-Rock Outcrop complex, 5 to 30 percent slopes, Water Index 10.09, AMT AMP Coordinate 9.9, 780
and image from observation 69461554 in Cady-Rock Outcrop complex, 5 to 30 percent slopes, Water Index 10.09m, AMT AMP Coordinate 9.9, 782.
These are among the warmest, high precipitation and mid range water index oak sites with the same values with the upland sites. The median values support the assumption of a high sodium soil.

The mesic wetland populations are a surprising physiological attribute of Q. garryana. In the Willamette Valley, in the winter Q. garryana may be observed standing in flooded or hydric soil. The wet soil likely prevents healthy mycorrhizal biosymbionts with the conifers and weakens the soil foundations making them susceptible to windthrow. Q. garryana is known on San Juan Island that are on a soil complex containing a hydric soil. These oak are generally large trees with full canopies and without conifer competition. Pseudotsuga menziesii the primary conifer competitor is considered to be intolerant of flooding. Examples are the;
image of 89937587 in the Mitchellbay-Sholander-Bazal complex, 0 to 8 percent slopes, Water Index 12.75, AMT AMP Coordinate 9.7, 773,
the image of observation 89978473 in the Mitchellbay gravelly sandy loam, 5 to 15 percent slopes, Water Index 15.25, AMT AMP Coordinate 9.7, 784,
the image of observation 132106814 in the Roche-Killebrew complex, 2 to 10 percent slopes, Water Index 15.95, AMT AMP Coordinate 9.6, 748,
and the image of observation 17148083 in the Coveland-Mitchellbay complex, 2 to 15 percent slopes, Water Index 16.14, AMT AMP Coordinate 9.8, 836,
the image of observation observation in the Cady-Rock Outcrop complex, 5 to 30 percent slopes, Water Index 10.09, AMT AMP Coordinate 9.7, 776

The upland population is in a range of soil moisture capacities from to moist. The driest soil habitat restricts the establishment of conifers. At the moist end conifer competition occurs. In the San Juan Islands this is mostly Pseudotsuga menziesii, a drought tolerant taxa. In soils with a low water index Q. garryana is a dominate canopy taxa. On the wet end the conifers are able to overtop and suppress Q. garryana and prevent reproduction.
Examples are the image of observation 73906103 in the Rock Outcrop-Haro complex, 25 to 75 percent slopes, Water Index 4.01 AMT AMP Coordinate 8.1, 780,
the image of observation 84612194 in the Haro-Hiddenridge-Rock Outcrop complex, 5 to 30 percent, Water Index 4.58 AMT AMP Coordinate 9.5, 779,
the image of observation 122191671 in the Cady-Doebay-Rock Outcrop complex, 25 to 75 percent slopes, Water Index 9.85, AMT AMP Coordinate 8.1, 783,
the image of observation 129864134 in the Whidbey gravelly loam, 3 to 15 percent slopes, Water Index 8.31, AMT AMP Coordinate 9.7, 773,
the image of observation 86668737 in the Doebay-Cady-Rock Outcrop complex, 10 to 30 percent slopes, Water Index 10.91, AMT AMP Coordinate 9.4, 778,
the image of observation 109601732 in the Doebay-Morancreek complex, 5 to 25 percent slopes, Water Index 13.4, AMT AMP Coordinate 9.4, 778.

As noted seasonal precipitation and soil moisture capacity requires addational analysis. The soil water capacity is producing a range of ecological dominances, a dominate oak, a subdominant oak, and a serial oak habitats. In soil that lacks moisture to support conifers Q. garryana is a stable dominate. In soil complexes of mixed moisture capacities a mosaic of Q. garryana and P. menziesii may exist with a dynamic changes in composition with climatic cycles but with separation of the two taxa.

Soil Map Unit----------------------------------------------------------------------- Water Capacity----Hydric Soil

Beaches-Endoaquents, tidal-Xerorthents association, 0 to 5 percent slopes---2.25----------------Complex
Rock Outcrop-Haro complex, 25 to 75 percent slopes---------------------------4.01
Haro-Hiddenridge-Rock Outcrop complex, 5 to 30 percent slopes-------------4.58
Haro-Hiddenridge-Rock Outcrop complex, 25 to 75 percent slopes------------4.58
San Juan sandy loam, 5 to 20 percent slopes-------------------------------------6.91
Whidbey gravelly loam, 3 to 15 percent slopes-----------------------------------8.31
Sucia-Sholander complex, 5 to 20 percent slopes--------------------------------8.73
Cady-Doebay-Rock Outcrop complex, 25 to 75 percent slopes-----------------9.58
Cady-Rock Outcrop complex, 5 to 30 percent slopes---------------------------10.09
Doebay-Cady-Rock Outcrop complex, 10 to 30 percent slopes----------------10.91
Doebay, moist-Cady-Rock Outcrop complex, 10 to 30 percent slopes --------10.91
Doebay, moist-Cady-Doebay complex, 25 to 75 percent slopes---------------11.26
Pilepoint loam, 2 to 8 percent slopes---------------------------------------------11.35
Mitchellbay-Sholander-Bazal complex, 0 to 8 percent slopes------------------12.75---------------Complex
Doebay-Morancreek complex, 5 to 25 percent slopes--------------------------13.4
Roche-Killebrew-Rock Outcrop complex, 5 to 35 percent slopes--------------14.59
Mitchellbay-Rock Outcrop-Killebrew complex, 3 to 15 percent slopes--------14.84
Roche-Killebrew complex, 2 to 10 percent slopes-------------------------------15.95---------------Complex
Mitchellbay gravelly sandy loam, 0 to 5 percent slopes------------------------16.05---------------Complex
Coveland-Mitchellbay complex, 2 to 15 percent slopes-------------------------16.14---------------Complex

Quercus garryana Climatic Range

AMT Range 17.4 - 6.1 Celsius --------------63.3 - 42.9 Fahrenheit
AMP Range 4130 - 264 mm---------------162.6 - 10.4 inch

San Juan Island Climatic Range

AMT Range 10.52 - 9.6 Celsius------------50.93 - 49.28 Fahrenheit
AMP Range 781 - 593 mm-------------------30.7 - 23.3 inch

The known MAT endpoints of Q. garryana is 16.4 C and 6.1 C, a range of 10.3 dC (61.5 dF to 43.0 dF.) Q. garryana is able to occupy any habitat between the hot and cold temperature boundaries. The MAP difference likewise is significant. Annual precipitation endpoints are 4,130 and 264 millimeters. This is an astounding 12.7 feet to 10.4 inches of annual precipitation. The high precipitation value is not an outlier as other high precipitation observations are similar but lower. This high value is a condition of high elevation winter precipitation and fast runoff on steep slopes. The growing season water that is mostly the soil water. The trees at the lower precipitation boundary are likely limited by heat stress and limited precipitation.

The lower value of AMP may require the removal of the obvious ground water hydration. For this reason future analysis requires a classification of Q. garryana as trees that supported by the climatic precipitation and those that are supported by groundwater. A clear example of groundwater supported oak is observation. This oak is riparian on the bank of the Deschutes River at a 10.9 C and 279 mm AMT AMP coordinate, terrain a vegetative community of sagebrush and grass. The San Juan Islands are completely within the zone of climatic precipitation.
Q. garryana occupies a precipitation niche on the east Cascade slope with and below Pinus ponderosa. The generally excepted limit for P. ponderosa is 16 inches MAP. This identifies the Q. garryana limit as less than Ps. menziesii's the 23 inch San Juan MAP but more then the P. ponderosa limit. Riparian Q. garryana in the east Cascades lower canyons are able to thrive at the MATs but observations suggest the MAP is above 280mm. It is suspected that a climatic decrease in the local summer precipitation or an increase in the MAT may have a negative impact on P. menziesii by increasing the mortality and fire vulnerability.

The San Juan Island Q. garryana are at the cooler end of the AMT range. It is unknown where the cold endpoint is within the islands. It is higher then 1000 feet but not known if it extents to the height of Mt. Constitution. The highest known local elevation of Q. garryana is on Mt. Tuam on Saltspring Island at 1727 feet. The high point of Mount Constitution is 2400 feet. This is an elevation that suggests the topographic range is adequate for a endpoint to be expressed. The known cold end point MAT is at high 5785 foot elevation in the Oregon Cascades. This Oregon Cascade Q. garryana occurrence is restricted to an isolated narrow rock habitats with southern exposure. This indicates that Q. garryana could be found at higher elevations in the islands but observations are lacking for establishing an end point. The wetter higher island locations may not provide competitive niches for Q. garryana.

Also of importance to the management of Q. garryana habitat and a second result of the climatic and edaphic variables is the associated vegetative associations. These are partly visible in the examples of the upland and mesic habitat. Future work should be undertaken to access the association structures as defined by Chappell 2004 and Buechling 2008. Chappell's work was conducted in the Puget Basin and is the first resource for the San Juan Islands. Buechling's work was conducted in the Willamette Valley and is complimentary to the San Juan environment. The upland and mesic observations demonstrate vegetative changes with the soil water capacity.

Posted on September 29, 2022 05:40 PM by carexobnupta carexobnupta

August 11, 2022

Quercus garryana varieties

The identification of the sub taxonomic identity of Quercus garryana is not without some risk of a misapplication. An assured identification requires observation of a number of morphological details. Additionally, the key features are variable over the course of a season, thus, spring and fall features present different appearances. Two diagnostic keys are aviable, the Jepson and the Flora of North America keys. These are similar but contain subtle descriptive narratives. Both keys split the taxa based on habit type of a single trunk or as shrubs or small trees.

The Jepson Quercus garryana eflora key to the varieties identifies var. garryana as a tree with large fusiform pubescent buds and with var. breweri and semota as scrub or shrubs with small red or brown buds. These are then separated by the abaxial leaves' stellate hair. The The Flora of North America key allows for separation based on the twig and bud pubescence. Thus, the keys should be interpreted as a choice between two combinations of features; tree and bud structure and pubesence, or scrub-shrub and twig and bud structure and pubesence. However, the plant structure is ambiguous as Q. g. var. garryana presents as tree, scrub, and shrub. The stature of Q. garryana is a function of climate and fire history, as the taxon is found as single stem stately trees and in the form of scrub-shrub thickets. High elevation oak in the Oregon Cascades is mostly that of a shrub structure. Fire also has a impact of the structure of the habit. The high elevation Q. garryana observations appear to be low and tall shrubs. This most likely is the result of fire and growing season. The ambiguity of habit can lead to a misapplication, therefore, the key should be reconsidered to consider the features of the twig and bud with habit as a secondary ambiguous characteristic.

The following observations demonstrate the bud characteristics of the Q. garryana taxa. Twig characteristics are not considered at this time as addational editing of the observations in needed. Changes in twig color over the growing season is not understood. More illustrative observations are required upon which to make a reasonable judgement. Also, needed is observations of the twig pubesence. Q. g. var. garryana twigs are densely pubesent where vars. breweri and semota are mostly glabrous.

Garry Oak Q. g. var. garryana

Brewer's Oak Q. g. var. breweri

Semota Oak

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Posted on August 11, 2022 05:01 AM by carexobnupta carexobnupta | 5 comments | Leave a comment

February 25, 2021

Quercus robur

Quercus robur or as it is known as English Oak or Pedunculate Oak is established and spreading in the range of Quercus garryana. Taxonomically Q. robur and Q. garryana are included in the same subgenus section Quercus the typical White Oaks. Many of the features of the White Oaks overlap creating uncertainty when identifying the taxa. and this oak is often mistaken for Q. garryana. The two species of oak can be differentiated by structure and canopy, bark color and texture, terminal bud size, texture, and color, and leaf outline and texture. Examples of these features are provided below with links to demonstrative observations. A well composed images of Q. garryana that demonstrate many of the Garry Oak features are at and A study of Q. robur is at

Acorn Morphology
Although the western oaks of North America can be identified by many features. The acorn is one of the most reliable characteristics upon which to base an identity and is an epically important identifying feature of the White Oaks. Both Q. garryana and Q. robur have projections, tubercles, around the acorn involucre also known as a cap. There are distinctive fine scale differences. The involucre tubercles of Q. garryana project upwards like worts, creating a course and rough corky surface, an example is the second image at Those of Q. robur are much less pronounced with a finely textured, egg-shale, surface and a velvety or pubescent feel see
Additionally the acorn is morphologically different from Q. garryana. The Q. robur acorn is generally smaller and long and narrow. Observation and demonstrate the longer acorn. Limited measurements of the nut are one inch or slightly more long and half of an inch in diameter. The Q. garryana acorn is larger with a general rotund width and equal length. An example may be viewed at
Q. robur is known as Pedunculate Oak from the distinctive arrangement of the acorns as the acorns are located at a distance from the terminal branch on a long thin stem, a peduncle, of the inflorescence, where the western White Oak acorns are sessile on the terminal branch. This character may be seen at Other Eurasian oaks are pedunculate, however this feature identifies the observation as Q. robur in western North America.

Observational Survey
A survey of Q. robur acorns may be viewed at
and Q. garryana at The survey of Q. robur suggests that some specimen have an outline that is similar to Q. garryana. However the scale is and size are unknown.

Leaf Morphology
The leaves of the western White Oak require study to differentiate from each other. Within each of the native oak species there is notable differences within each taxa. These may be the result of local environmental differences. Observation located in a hot dry canyon on the east slope of the Cascade Range demonstrates a reduced somewhat skeletal leaf with deep sinuses. This leaf form contrasts with the fuller rounder leaf typically found west of the Cascades. This reduced form is also known from the interior Coast Range of Northern California. The Oregon White Oaks found west of the Cascades contrasts with a typically fuller rounder leaf
The leaf base in 48569644 is a typical attenuate shape although the leaf base may also be rounded.
Q. garryana has a subtle feature that is quite distinctive, the secondary lobes. Observation demonstrates this characteristic. These lobes are best defined by the leaf veins. The primary lobe ends with a secondary vein that branches from the primary vein, the vein that extends from the petiole to the distal tip. The secondary lobes end with a vein that branches from a secondary vein. Thus the secondary lobe is a smaller part of the primary lobe. In Q. garryana this secondary lobes is nearly always present, although it may be reduced in size.
Q. robur has a number of subtle features that can help separate the two species. A leaf base feature that is cited as a defining character is an auriculate or ear-lobed base. See observation However this feature may not be present or evident. The leaf petiole is distinctive as it is very short or sessile. Observation features this type of petiole. Note that the leaf bases appear to be directly attached to the terminal bud. A secondary lobe is almost never present in English Oak.

Leaf Out-line
The complexity of the oak leaf is somewhat confusing as a result of the sinuses and lobes. This requires a mental exercise of tracing the outline without the sinuses or tracing the outline on paper from lobe tip to lobe tip. Q. garryana has a wide ovate-elliptical shape with the mid point near the primary axis center. The Q. robur outline is a narrow elliptical-spathulate shape with the mid point shifted to the distal end and that can be described as obovate. Examples are found at, the leaf in this observation lacks the auriculate leaf base and has an attenuate base and
Leaf Margin

Twig Morphology
The twigs of Q. garryana and Q. robur are notably different. The Oregon Oak twig is relatively thick and robust where English Oak is gracile. Q. garryana twig structure may be viewed at and the forth image at Q. robur at,,, and

Terminal Bud Morphology
The buds are one of the most reliable features to differentiate the two oaks. The buds in both oaks change over the seasons, in summer they are smaller and enlarging through fall and winter.
The large pubescent terminal buds of Oregon Oak are distinctive from English Oak which are small and glabrous. The terminal buds in Q. robur are small round or oval and glabrous the second image in Summer buds are green and winter buds before spring brake are reddish-chestnut. The buds in Q. garryana are large robust conical with dense rusty hair. Observation captures the size and shape of the winter bud. Here the summer hair color has weathered to a gray and the bud scales have also darkened.

Trunk and Canopy
Canopy Structure
There is considerable variance in the canopy structure Q. robur generally it is a thick dense closed canopy but some trees demonstrate a more open structure. Various canopies may be viewed at

The texture and color of the bark of Q. robur and Q. garryana are different. These are best understood by direct observation to understand the features.

Q. garryana has a thick bark with rows of plates more or less in rows and separated by deep narrow furrows, the color is light gray. Observation captures the typical aspect.
Q. robur bark has a thinner bark the ridges are smaller and light gray, the furrows are shallow and reddish brown in the shallow bottom. Observations and demonstrate. The bark in saplings and small diameter trees has a cherry bark like banding, observation

Morphological Range
Q. robur has a extensive range in the palearctic region. It appears that the morphology of the taxa may also reflect that range and that regional characters. The comparison between native and introduced oak in the Pacific West Coast region requires consideration of the origin of the Eurasian oak. There are observations that suggest grater variance then suggested. It is likely that addational features require consideration based to the origin and variance of this oak. Thus origin may influence the features under review and this should be considered.

Other taxa of Eurasian Quercus with pedunculate infloresences are known which suggests a need to examine the North American observations of Q. robur to determine if there is other taxa with these features that are being misapplied. Wikipedia reports the existence of synonyms, hybrids, and horticultural cultivars. This comparison is a consideration to separate Q. robur from Q. garryana within the range of Q. garryana.

Posted on February 25, 2021 11:54 PM by carexobnupta carexobnupta | 0 comments | Leave a comment

June 03, 2017

The Current Summary of Q. garryana on the Washington and Oregon East Cascade Slopes.

The current observation set was mapped against the Little Atlas Quercus garryana mapped range. The data set demonstrates the range is much more extensive than the mapped boundaries. Considerable oak is present in Klickitat County Washington east of Goldendale, Washington and in Wasco County Oregon in the area around Tygh Valley. The boundaries of the Omernik level III & IV EcoRegions have been found to be useful in describing the species range on the east slope. Currently, I am looking at the local soil types as an tool in identifying the local range. This is promising. In Washington the Gunn soil mappes the dominate oak woodlands. In Oregon the Skyline and Wamic soils define the occurrence of oak woodlands.

Posted on June 03, 2017 07:40 AM by carexobnupta carexobnupta | 0 comments | Leave a comment

June 27, 2016

26 June 2016

Started at Columbia City along the Columbia River, stopped at downtown St. Helens and McCormick Park, then took Old Portland Highway to Scappoose Bay Marina, transited the Warren Plain via Church Road and to the south. Oregon Oak common from Columbia City, St. Helens, to Scappoose along Highway 30. Occasional oak in Warren Plain. No oak observed from Scappoose to Buxton. Oregon Oak observed at Buxton at Highway 26 - Highway 47 intersection. Common along Highway 26 east of Highway 47 to urban development.

Posted on June 27, 2016 05:42 AM by carexobnupta carexobnupta | 0 comments | Leave a comment