Gr. Mcpherson et Jf. Weltzin, HERBACEOUS RESPONSE TO CANOPY REMOVAL IN SOUTHWESTERN OAK WOODLANDS, Journal of range management, 51(6), 1998, pp. 674-678
An understanding of overstory-understory relationships in southwestern
oak woodlands is important for predicting response of these systems t
o disturbance or manipulation, The objective of this study was to eval
uate the response of herbaceous plants to removal of the overstory in
evergreen oak woodlands. Overstory plants were removed from 30 X 30 m
plots in January 1993 and January 1994, and the response of herbaceous
plants in these plots was compared to untreated controls for 5 and 4
years, respectively, The C-4 graminoid and total biomass increased aft
er overstory removal to as much as 10 times greater than controls, rem
ained at elevated levels the second year, declined in subsequent years
to 3-7 times the production of controls, and increased slightly durin
g the final year of the study (1997), Overstory removal was necessary
but not sufficient to affect herbaceous dicot biomass, which increased
relative to controls during years with above-average winter precipita
tion. The C-3 graminoids did not respond to overstory removal.