A literature search revealed few reports concerning the influence of fire on native vegetation of the Texas High Plains. Consequently a study was initiated in 1965 to investigate the effects of burning upon this plant community at the Texas Technological College Research Farm near Amarillo city (southwest USA).
Main grasses comprised blue grama Bouteloua gracilis, sand dropseed Sporobolus crytandrus, windmillgrass Chloris verticillata, buffalograss Buchloe dactyloides, red threeawn Aristida longiseta and tumblegrass Schedonnardus paniculatus.
In 1965, six adjacent 100 x 50 ft (30.4 x 15.2 m) plots were established. Ten 0.89 m² quadrats were placed along a transect through each. In autumn 1965, 1966 and 1967, measurements of height, basal area and number of seed stalks were taken on 25 plants of blue grama, sand dropseed and red threeawn per plot; and basal area and 10 leaf lengths on 25 windmillgrass plants per plot. Herbage yields were determined at the end of the 1966 and 1967 growing seasons.
Two plots were burned in autumn 1965 (one with and the other against the wind), and two plots similarly in spring 1966. One plot was burned in summer 1966. One plot was unburned (control). Plots burned with the wind in autumn and spring1965 and 1966, were burned again a year later.
All burn treatments significantly reduced total forage production (by 15-35%) in the two years subsequent to burning (dry yield 1966: 916-1,078 lb/acre; 1967: 513-638 lb/acre) compared to the control (1966: 1,384 lb/acre; 1967: 962).
Although yields were less on burned plots, vigour of the main desirable forage grass, blue grama, appeared benefited by burning; basal area increased from 1966 to 1967 except in the plot burned in two consecutive springs. Burning appeared to reduce vigour of two less desirable grasses (threeawn and dropseed); burning significantly reduced seed stalk production of dropseed in both subsequent years.
Windmillgrass appeared resilient to fire, as burning had no influence on leaf lengths or basal cover.
Spring burning is recommended over autumn burning.
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