Palomino Playa Research Natural Area

Vale District , BLM

Northern Basin and Range Ecoregion

Cell(s):

• Bare playa with Davis' peppergrass

Access to playa by a small road north of State Highway 78 that is completely impassable when wet; accessible spring to fall when completely dry.

The 260 ha Palomino Playa RNA protects a dry playa lake near Saddle Butte Lava Fields, northwest of Burns Junction, Malheur County, Oregon. Summers are hot and dry, winters are cool and moist. Annual precipitation averages 15 to 20 cm. The 0.8-km long dry lakebed at 1250 m. is divided by a rocky finger. Shrink-swell clays in the lakebed hold water through winter and spring, then form wide cracks in polygonal patterns when they dry in the summer. The playa supports one of the largest populations of Davis' peppergrass (Lepidium davisii), a special status perennial plant found only on clay soil playas in the Owyhee Uplands of Oregon and Idaho. Palomino Playa is classed as a barren playa because lacks cover by large shrubs such as silver sagebrush (Artemisia cana) or greasewood (Sarcobatus vermiculatus). Unlike other playa lakes that have silty soils from sedimentation in pluvial lakes in large basins, or sandy soils with high concentrations of alkali salts from evaporation, Palomino Playa soils are high in clay, products of the decomposition of volcanic ash commonly found in the Owyhee Uplands. The upland soils are shallow loams over basalt and are dominated by a shadscale saltbush-greasewood (Atriplex canescens/Sarcobatus vermiculatus) community at the lowest elevations, followed by Wyoming big sagebrush-greasewood (Artemisia tridentata ssp. wyomingensis/Sarcobatus vermiculatus) at slightly higher elevations. Because elevation differences are small (3 to 6 m), community changes mostly relate to alkaline soil conditions. Few associated species grow in the shadscale saltbush/greasewood/sagebrush communities; even the grasses have been reduced to scattered bunches of bottlebrush squirreltail (Elymus elymoides). Two noxious weeds, Halogeton glomeratus and Lepidium perfoliatum, are common in the salt desert shrub uplands, and the noxious povertyweed, Iva axillaris, is found in pockets on the playa. Past and current disturbance includes light grazing by livestock in summer; year-round use by wild horses; and a road, which is closed, which bisects the playa.