Madrean Lower Montane Pine-Oak Forest and Woodland

 

 

 

The Galiuros are not a tall range (only 7663 feet at Bassett Peak) yet hold remarkable swaths of the Madrean Lower Montane Pine-Oak Forest and Woodland ecosystem. The hallmark of the ecosystem is big conifers: Douglas fir (Psuedotsuga menziesii), Arizona cypress (Cupressus arizonica), ponderosa pine (Pinus ponderosa), Chihuahuan Pine (P. leiophylla var. chihuahuana = P. chihuahuana), and a white pine that is either P. flexilis or P. strobiformis. The ecosystem runs along the floor of most major canyons, with ponderosa and Chihuahuan pine reaching elevations as low as 4700 feet. At lower elevations, associated species are generally Emory oak and alligator juniper, both of which are often more common than the pines or cypress.

 

The pine-oak ecosystem also occupies certain north slopes, but with significant changes from the canyon bottom habitat. Chihuahuan pine drops out, and Douglas fir becomes prominent, joined by deciduous bigtooth maple and Gambel oak. The most mesic bits of habitat, such as the north slope of Kennedy Peak (7540 feet), lacked Madrean oaks, and hence could be considered part of the Southern Rocky Mountain Dry-Mesic Montane Mixed Conifer Forest and Woodland (www.natureserve.org). It was not mapped as such, because the extent is so small, and because Madrean oaks, especially silverleaf and netleaf, are always nearby, common on sunnier aspects.

 

As mentioned in the description of the Madrean Pinyon-Juniper Woodland, the steep and rocky landforms that favor pinyon-juniper are also strongly correlated with the pine-oak ecosystem in the Galiuros, possibly because of enhanced runoff or the soils. In any case, in the northern reaches of the study site, in the watershed of Four-Mile Canyon, there is no Madrean Pine-Oak, at least as defined in this study. Many areas of the Four-Mile watershed seem plenty rocky, especially in the west, yet the most of the watershed is Madrean Encinal (oak/grass dominated) or Great Basin Pinyon-Juniper (single-needle pinyon). There was no evidence of Douglas fir, Ponderosa pine, or Chihuahuan pine, despite Four Mile Canyon being a relatively wet canyon, with numerous springs.

 

Further south, in the Rattlesnake watershed, ponderosa pine is abundant, and remarkably free of mistletoe. Still further south, around Bassett Peak, the big pine wanes and is missing for the most part. While hiking up Ash Canyon to Bassett, ponderosa is common only for a half-mile stretch of canyon bottom – and a relatively dry stretch, too.

 

However, this was the same canyon that holds a species of pine with characters intermediate to Southwestern white pine, P. strobiformis, and limber pine, P. flexilis. It is not common, and instead the pine-oak in the southern Galiuros is dominated by Douglas fir and border pinyon (P. discolor).

 

NOTE: The Madrean Pine-Oak mapped on north slopes (which is about two-thirds of the pine-oak mapped in this study, with the remainder occupying canyon floors) would be part of "Madrean Oak-Conifer-Manzanita on Rocks" ecosystem mapped previously in the Rincons, Catalinas, Chiricahuas, Dos Cabezas, and Dragoons. The canyon floors, in most instances, would not be mapped as such. Distinguishing between the two habitats – slope and canyon floor – can be done with digital elevation models and GIS skills.

 

The view down Rattlesnake Canyon, just north of Powers Garden. Near this photo station at 4930 feet (1500 m), ponderosa pine averaged 20-22 m tall and gave 15-25% cover, while Chihuahuan pine were only 5 m tall, with 1-4% cover. The relative amounts of these two pines can change swiftly, with the Chihuahuan pine prevailing on drier aspects. Alligator junipers added little cover – 1 to 4% – but were often large, averaging 10 m. Cypress and sycamore, 15 m and 10 m, mostly traced the unseen rocky bed of (dry) Rattlesnake Creek, but did not exceed 4% cover combined at this photo station. Manzanita popped up in sunny patches, adding another 1-4%. Emory oak and border pinyon were restricted to the understory, with 1-4% cover. Grasses, especially bullgrass and spidergrass, were common here, as were tall stalks of wooly mullein (Verbascum thapsus). 14 May 2011.

 

A north slope in Pipestem Canyon, a half-mile above its confluence with Rattlesnake Canyon. The bright green is bigtooth maple (Acer grandidentatum), among Ponderosa pine, Gambel oak, border pinyon, and oak. 4750 feet (1440 m), 14 May 2011.

 

A stand of cypress (Cupressus arizonica) along Rattlesnake Canyon, a quarter mile up from Rattlesnake Spring, at 5400 feet (1650 m) on 16 May 2011. This view, facing southwest, misses some of the big trees in favor of showing the downed wood and relatively dense understory of netleaf oak (2 m tall) joined by silverleaf oak, deerbrush (Ceanothus integerrimus), coffeberry (Rhamnus californica), and border pinyon (Pinus discolor). The adult cypresses are tall – around 80 feet (25 m) – and dominate with 40-80% cover. Nothing else comes close, although the ponderosa pine get taller yet – an estimated 90 feet (28 m) – and give another 5% cover, along with Douglas fir (25 m). 

 

The view east along a north slope, about two hundred feet above the floor of Rattlesnake Canyon, about ½ mile west of Holdout Spring. 16 May 2011, 5800 ft (1760 m). The tall tree at center is a cypress. This slope was steep, loose, and diverse. The most common woody plants were an understory of Quercus rugosa and Quercus hypoleucoides, each about 6 to 8 feet tall, and each with 15-25% cover. Border pinyon (Pinus discolor) averaged 20 feet tall, and 15-25% cover. Associates included cypress (averaged 20 feet, 10-14% cover), Chihuahuan pine (45 ft, 1-4%), ponderosa pine (45 ft, 1-4%), Douglas fir (45 feet, 10-14%) alligator juniper (30 feet, 1-4%), and manzanita (4 ft, 1-4%.) See also Photo Point 531.

 

The view down the trail along Rattlesnake Canyon, 5900 feet (1800 m), under the arching canopy of bigtooth maple (Acer grandidentatum), typically 35-40 feet tall, with 60-80% cover. This stretch of mesic canyon bottom switches back and forth from maple to Gambel oak, which is also tall (45 feet) and can form a canopy. Still other places can be dominated by 7 foot tall netleaf oak (Quercus rugosa), with over 80% cover. Several aspen, old and isolated, are nearby, upcanyon. Here and there are pockets of false Solomon's-seal, Maianthemum racemosum (=Smilacina racemosa), a shade-loving species. 16 May 2011.

 

 

The view SSE at 6700 feet (2040m) along the north fork of Douglas Canyon, 17 May 2011. The dominant species are Douglas fir and Ponderosa pine, with associated Gambel and netleaf oak (Quercus gambellii and Q. rugosa). The open understory contrasts with nearby Photo Point 623, below.

The view east at 6650 feet (2020m) along the north fork of Douglas Canyon, 17 May 2011. The big conifers are mostly Douglas fir and Ponderosa pine. The heavy underbrush, mostly netleaf oak (Quercus rugosa) contrasts with nearby Photo Point 627, above.

 

The north slope of Kennedy Peak, at 7050 ft (2150 m), East Divide Trail, 17 May 2011. Douglas fir dominates (50 feet tall (15 m), 40-60% cover), with associated Gambel oak (10 m, 10-25%) and ponderosa pine (15 m, 5-9%). Netleaf and silverleaf oak are notably absent, although they are only 100 meters from the photo point. Common shrubs/small trees included snowberry (Symphoricarpos oreophilus), hoptree (Ptelea trifoliata), rock-spirea (Holodiscus dumosus), border pinyon (Pinus discolor), and chokecherry (Prunus sp.).

 

The view NW from the Ash Creek Trail, 6700 feet (2050 m), about 200 meters east of its junction with the East Divide Trail, on 3 October 2011. Here the pine-oak ecosystem reaches nearly to the ridgeline. What's unusual is the presence of a white pine, either Pinus flexilis or P. strobiformis (under review), which apparently only lives in the watershed of Ash Canyon, below Bassett Peak. The white pine, shown here by the branch in the right upper view, and the tree leaning next to the big snag at center, lives in the company of border pinyon (Pinus discolor), with the two species combining for 25-40% cover. Equally common is a relatively low (2-3 m) layer of silverleaf, netleaf, and scrub oak (Q. hypoleucoides, Q. rugosa, Q. turbinella). There are no ponderosa or Chihuahuan pine, but Douglas fir contributes another 5-9% cover.

 

 

The Madrean Pine-Oak ecosystem includes elements of several vegetation types mapped or described in other classification schemes. In each of the seven schemes referred to below, the * symbol marks the vegetation type most similar to the Madrean Pine-Oak ecological system.

 

And what is meant by ‘most similar’? For the USFS Plant “Habitat Type” (Potential Association) and the Brown, Lowe, and Pase “Biome”, the * symbol denotes the best fit based on the description of the Habitat Type or Biome. For the Landfire, ReGap, and USFS PNVT and mid-scale dominance classifications, which are presently mapped as 30 meter pixels, the * symbol denotes the classification that was most commonly attributed within the Madrean Pine-Oak, as mapped in this effort. The actual percentage attributed is given in parenthesis (%).

 

For example, the Madrean Pine-Oak polygons created by this study were used as a 'cookie-cutter' on the Landfire Existing Vegetation Type (EVT) layer (see methods). Within this study’s Madrean Pine-Oak ecosystem, 29% of the EVT pixels were attributed as Madrean Encinal, 28% as Madrean Pinyon-Juniper, 22% as Madrean Pine-Oak, and 12% as Rocky Mountain Warm Desert Riparian Systems.

 

Landfire Existing Vegetation Type (EVT, version 1.0.5)

Madrean Encinal * (29%)

Madrean Pinyon-Juniper Woodland * (28%)

Madrean Lower Montane Pine-Oak Forest and Woodland (22%)

Rocky Mountain Warm Desert Riparian Systems (12%)

Mogollon Chaparral (includes (Q. turbinella alliance) (6%)

Southern Rocky Mountain Ponderosa Pine (1%)

 

Landfire Biophysical Setting (BpS, version 1.0.0, which is older but judged by the author as locally more accurate)

Madrean Pinyon-Juniper Woodland * (25%)

Madrean Encinal * (25%)

Rocky Mountain Montane Riparian Systems * (23%)

Madrean Lower Montane Pine-Oak Forest and Woodland (20%)

Mogollon Chaparral (4%)

 

Madrean Pine-Oak * (62%) (PINUS_QUERC)

Oak-Juniper-Pinyon Mix (22%) (JUDE2, JUDE2_QUAR, JUDE2_QUEM, JUDE2_QUERC, JUMO, JUNIP_QUERC, PICEB, PIMO, QUAR, QUAR_QUEM, QUEM, QUEM_QUOB, QUERC, QUOB)

Upper Evergreen Forest Tree Mix (9%) (PIPO_PSME, PSME, TETX)

Ponderosa Pine (6%)

Note: the mid-scale map attributed 27,987 acres (11,326 ha) as 'upper-pine oak', while this study attributed only 6842 acres (2769 ha).

Pseudotsuga menziesii/Acer grandidentatum  PSME/ACGR

Pseudotsuga menziesii/Quercus gambelii PSME/QUGA

Pseudotsuga menziesii/Quercus hypoleucoides PSME/QUHY

 

Pinus ponderosa/Quercus gambelii PIPO/QUGA

Pinus ponderosa/Quercus hypoleucoides PIPO/QUHY

Pinus ponderosa/Acer grandidentatum PIPO/ACGR

 

Pinus leiophylla var. chihuahuana (=Pinus chihuahuana)/Quercus emoryi   PILE/QUEM

 

Cupressus arizonica/Quercus hypoleucoides CUAR/QUHY

 

USFS Potential Natural Vegetation Type (PNVT) based on 24 Oct 2011 draft map

Madrean Pine-oak Woodland * (66%)

Mixed conifer – Frequent Fire (18%)

Interior Chaparral (13%)

Madrean Encinal (3%)

Brown, Lowe, and Pase Biome

Madrean Evergreen Forest and Woodland (Encinal Series)

 

Southwest Regional GAP Ecological System

Madrean Pine-oak * (64%)

Rocky Mountain Ponderosa Pine (18%)

Mogollon Chaparral (14%)

Madrean Pinyon–Juniper (2%)