Culture and Ecology of Chaco Canyon and the San Juan Basin

Environment and Natural Resources 37R. Powers et al. (1983:8-9, 288-290) used datafrom the Soil Conservation Service and by Maker,Bullock, and Anderson (1974) to examine six landclasses in the San Juan Basin. Although the areascovered by a single land class were often larger thanthe area probably farmed during the Pueblo adaptation,the land in Chaco Canyon fell into classes 3 and4, which were thought to be moderately to severelylimited for irrigation. Class 1 and class 2 landsexisted around the perimeter; e.g., in the San JuanValley, the Chuska Valley, and drainages around thenorth and south perimeters of Lobo Mesa. Powers etal. (1983:289) recognized that the land-class ratingsdefined only general differences and that variability inprecipitation may have been more important than soiland hydrological factors in determining the location ofthe Chacoan structures in their study sample. Theonly Chacoan structures not located on class 1 or class2 soils were in the canyon and Kin Bineola. Both ofthese locations have evidence for water controlfeatures (Lyons, Inglis, and Hitchcock 1972; Lyons,Hitchcock, and Pouls 1976; Gwinn Vivian 1974b,1990).FloraBrand (1937c:46-47) characterized the canyonfloor as a Great Basin microphyll desert. During the1930s, sparse vegetation near site Bc 50 consisted of"chico or black greasewood (Sarcobatus venniculatus),tumble weed or Russian thistle (Salsola pestijer),crownbeard or smelling sunflower (Verbesinaenceliodes exauriculata), and scattered grasses.Herbaceous forms dominate; there is no tree growth;and the chico is the only shrub in the immediate area"(Brand 1937c:39). On the alluvial flats, sagebrush(Artemisia) was the dominant shrub; but greasewood(Sarcobatus vermiculatus) , bunch grasses(Sporobolus), rubberweed (Hymenoxys), tumble weed(Salsola pestijer), salt bushes (Atriplex), rabbit brush(Chrysothamnus) , blue grama (Bouteloua gracilus),galleta grass (Hilaria jamesii), feather grass (Stipa),poverty grass (Aristida), crownbeard (Verbesina), andothers were present. Yuccas and cacti were found ontalus slopes, rocky ledges, and other mesa and valleysurfaces. On sandstone ridges and mesas wereJuniperus (also known as cedars), pinon (Pinusedulis), and sagebrush (Artemisia). Steppe grassesappeared in parklike openings in these settings. Invegetated areas between the mesa levels weresagebrush, rubberweed, blue grama grass, pricklypear, and cane cacti (Opuntia). Joint fir (Ephedra)and redtop grass (Agrostis) were found in very sandysoils; around ponds and lakes in the area are foundcarrizo (Phragmites phragmites), rushes (Juncus) ,bullrushes (Scripus), and sedges (Carex).Brand (1937c:53-55) identified species that wereused for food, medicine, dyes, fibers, matting, andbaskets. Later, Elmore (1943) conducted ethnobotanicalstudies of the Navajo and began collectionsfor a herbarium. By 1965, Gordon Vivian andMathews (1965:23-24) were able to expand thedescription of available flora. Although there is nogreat abundance or wide diversification of plants, thevegetation was characterized as predominantly UpperSonoran with some remnants of the Transitional inmore sheltered coves, and re-entrants. They listedspecies by the general areas in which they were found(canyon floor, exposed soils at outwashes from fromside entrants, and at junctures of the Chaco andEscavada, arroyo bottom, mesa tops, and other higherelevations). Vivian and Mathews (1965) recognizedthat the lists were incomplete, especially for higherand more remote areas on Chacra Mesa. It was theirimpression that erosion control measures taken duringthe 1930s resulted in an increase of black greasewoodand larger shrubs on the canyon bottom. It was in theintermediate zone between the mesa tops and canyonfloor, however, that they noted the greatest variationin vegetation and the largest number of species.By 1969, the wash contained a few trees plantedduring an erosion control program; today, there issome natural recivitment. Species introduced by theSoil Conservation Service during a three-year period(1933 to 1936) include tamarisk (Tamarix); willow(Salix); broad leaf cottonwood (Populus wislizeni);narrow leaf cottonwood (P. angustijolia); wild plum(Prunus americana); Parosela shrubs; western wheatgrass, or bluestem (Argopyron smithii); sacaton (Sporobolus);and sand bunchgrass (Oryzopsis hymenoides)(Brand1937c:47 Footnote 12; Gordon Vivianand Mathews 1965:5). Relict stands of pine trees anda few Douglas-firs existed along Chacra Mesa. In thecentral canyon, relict individual Pinus ponderosa werecut down for firewood. In the 1990s, Windes (personalcommunication, 2003) noted a few individualsupcanyon near the Chaco East community. Healthypopulations are found in higher elevations, toward