Field Notes: Corral Bluffs, Sept 27th, 2008
Tass Kelso

 We visited both the upper portion of Corral Bluffs around the Hilaire property and some of the lower flats east of the Bishop property off CO94. Some of the cliff face communities were also viewed. The area surveyed consisted of 3 different plant communities, all in good condition with relatively few non-native or noxious weed species; these communities interfinger somewhat and differ in the amounts and types of certain species: the upper grasslands have more shortgrass prairie species and forbs, the cliff faces have more shrub cover and only scattered forbs and grasses, and the lower portions had a higher component of tall to midgrass species that are typical of moister and/or deeper sandy soils, along with sand specialist species. No rare species or communities were noted. 

 The upper plateau is dominated by shortgrass prairie typical of plains east of Colorado, where the most abundant grass is blue grama (Bouteloua gracilis);  grassland cover here is high, with few signs of overgrazing. Scattered and abundant herbaceous plants are also typical of this kind of grassland, with somewhat alkaline soils. 

Grasses
Bouteloua gracilis (blue grama)
Stipa viridis (green needlegrass)
Aristida purpurea (3 awn)
Sporobolus cryptandrus (dropseed)
Calamovilfa longifolia (prairie sandreed)
Bouteloua curtipendula (sideoats grama) 

Shrubs
Rhus trilobata (3 leaf sumac)
Kraschennikovia lanata (winterfat)
Ribes cereum (wax current)
Ribes aureum (golden current)
Rosa sp. (wild rose)
Chrysothamnus/Ericameria nauseosus (rabbitbrush)
Symphoricarpos cf. occidentalis (snowberry)
Cercocarpus montanus (mt. mahogany)
Prunus virginiana (chokecherry) 

Forbs
Liatris punctata (Kansas gayfeather)
Senecio spartioides (Senecio)
Lupinus spp. (lupines)
Oxtropis  spp.(locoweed)
Ratibida columnifera (coneflower)
Yucca glauca (yucca)
Cynoglossum officinale* (hounds tongue): significant infestation; aggressive adventive species in disturbed area

 The canyon face consisted of more open  soils, and vegetation composed of a few (generally scattered) grasses (notably sideoats grama and dropseed) and more individuals of shrubs such as mt. mahogany, occasional single seed juniper (Juniperus monosperma). Cliff faces are eroded, with a few flat shelves with open sandy soils. In late summer condition, few flowering species were noted; one that was quite abundant, however, was Eriogonum jamesii (James wild buckwheat) 

The lower sandy arroyos consisted of deeper, looser sandy soils and clear erosion channels with signs of ongoing  flood disturbance/erosion in the arroyo channels. Side vegetation was composed of dry, sandy grasslands, with more common occurrence of species such as little bluestem, Canada wildrye, and prairie sandreed, along with occasional individuals of big bluestem where moisture is more abundant. We did not survey much beyond the arroyo channels, but observed at some distance the flatter benches above the flood channels; these appeared to be mixed vegetation  but generally highly native in context. A few noxious species were noted here: tamarisk and oriental clematis both occurred, the latter somewhat abundantly. 

Grasses
Calamovilfa longifolia (prairie sandreed)
Andropogon gerardii (big bluestem)
Elymus canadensis (Canada wildrye)
Oryzopsis hymenoides  (Indian rice grass)
Distichlis stricta (saltgrass) 

Shrubs
Most of the xeric upper plateau shrubs (rabbitbrush, mt. mahogany, 3-leaf sumac)
Tamarix ramossisma (tamarisk)* noxious species, several large individuals observed 

Forbs
Helianthus  sp. (sunflower)
Dalea candida (white dalea)
Ambrosia psilostachya (ragweed)
Amaranthus blitoides (mat amaranth)
Chamaesyce missurica (prairie sandmat)
Chenopodium subglabrum (smooth goosefoot) 

Given the late season, little was in bloom in the arroyo channels, but the visible flora and soils composed of deep open sand suggest the likelihood in these arroyos of additional open sand endemics, which would be visible earlier in the summer, esp. under conditions when moisture is abundant. The significant drought this summer probably diminished the occurrence of sand annuals this year.