Culture and Ecology of Chaco Canyon and the San Juan Basin

- -~~------~- --- - ---------------42 Chaco Project Synthesiscantha] and winterfat [Ceratoides lanata]) were relativelyunchanged by the drought. Differences in plantpopUlations were noted in an area where thereformerly had been a blacktailed prairie dog (Cynomysludovicianus) town.Transects placed across vegetative communitiesdesignated by Potter (E. Kelley and Potter 1974;Potter 1974; Potter and Kelley 1980) were used tostudy numbers of plant species in Chaco Canyon. Thehabitats included the bench, the pinon-juniperwoodland, two floodplain areas (Casa Chiquita andPueblo Bonito), the wash, the shrub grassland atPueblo Alto, and a similar vegetative community inWerito's Rincon. A. Cully and Cully (1985:Table 2)reported that 12 species of plants (Table 2.2) wereimportant in discriminating among habitats. All butfalse terragon (Artemesia dracunculoides) were dominantswithin habitats. The wash, floodplain, bench,and mesa tops were distinct habitats that could bedistinguished either by species unique to the habitat orby a greater dominance of a particular species. Therewere definite similarities between the study areas atCasa Chiquita and Pueblo Bonito, and the bench andpinon-juniper woodlands were also similar. Withregard to species diversity, the bench had the secondhighest richness, the highest diversity, and the lowestcover. The two floodplain sites, Casa Chiquita andPueblo Bonito, had lower plant diversity than thebench; Casa Chiquita had similar cover, but at PuebloBonito the cover was slightly higher. Plant speciesand biomass varied by year; the plant species werehigher during 1979, when several storms occurred tobring additional precipitation. Biomass differenceswere attributed to species composition and soilconditions, but water availability was most influential.A. Cully and Cully's (1985) results differedslightly from those reported by Potter (1974) andJones (1972), probably because the methods employedin each study were different and because there wereactual changes in the abundance of perennial plants(also noted by Jones [1972] and documented by Scott[1980]). All three studies point to variability inannual plant production, which correlated withprecipitation.The major conclusion to be drawn fromthis study is that both annual and perennialplant species vary between habitats andTable 2.2. Plants important for discriminatinghabitats. aCommon nameBroadscaleFourwing saltbushSagebrushBigelow rabbitbrushGreasewoodJuniperGalleta grassIndian ricegrassFalse terragonCoyote willowTamariskJoint-firSpeciesAtriplex obovataAtriples canescensArtemisia bigeloviiChrysothamnusnauseosusSarcobatus vermiculatusJuniperus monospermaHilaria jamesiiOryzopsis hymenoidesArtemisia dracunculoidesSalix exiguaTamarix pentandraEphedra viridisa Taken from A. Cully and Cully (1985:Table 2).that resources may be available duringdifferent years in different habitats. Thesecond conclusion is that those habitatswith the highest alpha diversity may be thepoorest in terms of food production, andthat the variety of species present isaccompanied by low biomass. (A. Cullyand Cully 1985b:73)Plants are also affected by human disturbancesand may provide useful information for the archaeologist.Young and Potter (1974; Potter and Young1983) selected three sites on mesas and in valleys fromeach of four periods (Basketmaker III, with two mesasites; Pueblo I; Pueblo II; and Late Pueblo III). Theyalso examined several sections of prehistoric roadwaysand three isolated great kivas. Based on specific waterand soil requirements, most plant species providedclues to the type of structure, but they did not provideclues to help date the sites. Nine plant species were'I