Gravelly 20-24" PZ

Description

The Tallgrass/Midgrass Community is a fire-influenced tall and midgrass plant community. Shrubs are widely scattered along the slopes and tops, but make up 10 percent, or less, of the total plant community. Recurring fires have kept woody and cacti species in check, but forbs are relatively abundant. Sideoats grama and little bluestem are the dominant or co-dominant grasses throughout the site. There are other tallgrasses occurring on the site, but in smaller amounts. Common shortgrasses include hairy grama, blue grama, buffalograss, and occasionally black grama. Characteristic forbs are catclaw sensitivebriar, plains actinea, dotted gayfeather, black Samson, baby white aster and golden dalea. The primary woody plant is catclaw mimosa with lesser amounts of feather dalea, skunkbush sumac, yucca, and redberry juniper.

The Midgrass/Shortgrass/Shrubs Community developed due to the lack of fire along with overgrazing and has reduced the more palatable species and opened up the grass cover for the invasion of the woody species that had been held in check by competition and fire. Redberry juniper, yucca, pricklypear and occasionally mesquite may increase in number and size, but are not seriously impacting forage production at this point. The encroaching brushy species are generally less than four feet tall and provide less than 15 percent canopy. Less palatable grasses, such as hairy grama, hairy tridens, threeawns and sand dropseed along with forbs such as goldenaster, plains greenthread and Lamberts crazyweed are beginning to replace the dominants of the reference community.

Submodel

Description

The Shrubland State on the Gravelly site is the result of long-term overgrazing by livestock accompanied by the decrease in intensity and frequency of fires. Redberry juniper, yucca, pricklypear, broom snakeweed, mesquite and occasionally Havard oak may become the dominant woody species. There are several Gravelly site areas in western MLRA 78B that are dominated by Havard oak (>50%). On other Gravelly sites, mesquite was an early invader, but juniper has increased considerably the past few decades and often dominates the plant community. The most common woody invader of this site is broom snakeweed. Common understory shrubs and herbaceous vegetation in the interspaces include catclaw mimosa, feather dalea, and skunkbush sumac with low quality shortgrasses and annuals replacing the tall and midgrass species. Characteristic grasses are hairy tridens, hairy grama, threeawns, and sand dropseed. As the brush canopy increases in density and thickens, and the percent bare ground increases. Only sparse stands of hairy tridens, threeawns, Texas grama and annuals will occupy the interspaces between the woody plants or motts.

Submodel