North American Warm Desert Riparian

Cottonwood and ash are abundant in the Four Mile Canyon at the northern end of the study area. This view is south, upcanyon, at about 4500 feet, on 26 September 2011. The riparian trees are festooned with canyon grape (Vitis arizonica) and poison ivy, with some vines as thick as a man's wrist.

 

The view up Redfield Canyon near its confluence with Jackson Canyon, at 4000 feet, on 23 September 2010, 4000 feet. Although long stretches of Redfield hold no surface water for much of the year, the canyon supports a distinctly riparian assemblage of sycamore (Platanus wrightii), alder (Alnus oblongifolia), willow (Salix bonplandiana), walnut (Juglans major), and hackberry (Celtis reticulata). Photo by Lon and Queta.

 

 

 

 

The presence of cottonwood, willow, walnut and sycamore are the surest indicators of the North American Warm Desert Riparian ecosystem, for they cannot persist outside the riparian corridor. As mapped in this study, the ecosystem ranges from 3900 feet, where Rattlesnake Canyon exits the National Forest, up to 5000 feet, at Mitchell Spring.

 

For this study, the North American Warm Desert Riparian ecosystem is distinguished from the cooler Rocky Mountain Montane Riparian by the lack of big pines (meaning, all pines but pinyon) and cypress. The transition from one to the other occurred in two places: near the confluence of Rattlesnake and Pipestem Canyons and near the confluence of Redfield Canyon and Gold Gulch (just south of Hooker Cabin). Elsewhere, the Warm Desert Riparian usually graded upsteam into Madrean Lower Montane Pine-Oak, as obligate riparian species were replaced with big pines and cypress that were capable of living both in the canyon bottom and on the slopes.

 

This ecosystem, while called riparian, has dry stretches at a scale too fine to map for this study. Yet although long stretches may be dry for much of the year, subsurface water supports unusually large trees. For instance, in Redfield, there are hackberries (Celtis reticulata) up to 50 feet tall.

 

Finally, short stretches of outstanding riparian habitat were mapped, sometimes only a quarter mile long, such as Norton Spring in Scanlon Wash, and Mitchell Spring in its namesake canyon. The latter holds willow, ash, cottonwood, sycamore, walnut, willow, cattails and, in September of 2001, thousands of blooming cardinal flower, Lobelia cardinalis.

 

Canyons mapped in this ecosystem include:

 

Four Mile Canyon

Sycamore Canyon

Redfield Canyon

Oak Creek

Rattlesnake Creek

Paddy's River

Norton Spring, in upper Scanlon Wash (west side, near Sombrero Butte)

Pipeline Canyon (a west side tributary of Copper Creek)

Kielberg Canyon

Sunset Canyon

Negro Canyon

South Negro Canyon

Jackson Canyon

Mitchell Canyon

Bear Canyon

 

 

The North American Warm Desert Riparian ecosystem includes elements of several vegetation types mapped or described in other classification schemes. In each of the six schemes referred to below, the * symbol marks the vegetation type most similar to the Warm Desert Riparian.

 

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 Warm Desert Riparian, as mapped in this effort. The actual percentage attributed is given in parenthesis (%).

 

For example, the grassland 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 Warm Desert Riparian ecosystem, 27% of the EVT pixels were attributed as Warm Desert Riparian, while 24% were Mogollon Chaparral, and 20% were Madrean Mixed Juniper.

 

 

North American Warm Desert Riparian* (27%)

Mogollon Chaparral (24%)

Madrean Pinyon-juniper (20%)

 

North American Warm Desert Riparian Systems - Stringers * (37%)

Mogollon Chaparral (28%)

Madrean Pinyon-Juniper (11%)

Rocky Mountain Montane Riparian (9%)

North American Warm Desert Riparian (7%)

 

Oak Juniper-Pinyon * (71%) (JUDE2, JUDE2_QUAR, JUDE2_QUEM, JUDE2_QUERC, JUMO, JUNIP_QUERC, PICEB, PIMO, QUAR, QUAR_QUEM, QUEM, QUEM_QUOB, QUERC, QUOB)

Upper Pine-Oak (14%) (PINUS_QUERC)

(Note: the Coronado Mid-scale map did not map riparian habitat, and hence had no riparian vegetation type)

 

 

Brown, Lowe, and Pase Biome

Interior Southwestern Riparian Deciduous Forest and Woodland

 

Southwest Regional GAP Ecological System

Mogollon chaparral * (63%)

Mesquite upland shrub (18%)

Madrean pine-oak (11%)

Madrean pinyon-juniper (6%)