Vegetation Responses to 2 Brush Management Practices in South Texas

Abstract

Brush management for improving wildlife habitat in SouthTexas is important because of the economic value of wildlife. We determined vegetation responses to (1) roller chopping of guajillo (AcaciaberIandieriBenth.)-blackbrush acacia (A. rigidulaBenth.)dominated rangeland and (2) heavy dischrg of whitebrush (Aloysia &ioides Cham.)-dominated rangeland to improve white-tailed deer (Odocoileus virginianus Raf.) habitat. Canopy cover of vegetation was estimated seasonally during August 1988 to April 1990. Both treatments reduced brush canopy cover, but herbaceous response depended on rainfall. Mean herbaceous cover was 65 and 136% higher on roller chopped sites than on untreated sites when averaged across all sampllng dates. Heavy diseing reduced relative canopy cover of whltebrush but increased cover of spiny hackberry (Celtis pallida Torr.), an important browse species. Forb species richness was higher on roller chopped and disced sites than on untreated sites, but species diversity was similar. Because herbaceous response to brush removal may depend on rainfall, other factors such as effects on browse availability and nutritional quality may need to be considered when plannhrg brush management strategies to improve white-tailed deer habitat.

Nutrient Enrichment, Tannins, and Thorns: Effects on Browsing of Shrub Seedlings

“…Although both species coexist in nutrient-limited habitats throughout most of their range, blackbrush acacia seedlings are smaller and are more physically defended than guajillo seedlings. The lower height and mass of blackbrush acacia seedlings, relative to guajillo seedlings, is consis-tent with observations that sprouts of mature blackbrush acacia grow less rapidly than those of mature guajillo following removal of top growth (Bozzo et al 1992, Reynolds et al 1992. Anti-herbivore defense strategies of the 2 species were similar in that both species had high tannin concentrations when nutrients were limited.…”

“…Although blackbrush acacia and guajillo occur sympatrically on calcareous, relatively infertile soils, guajillo appears to grow relatively rapidly following plant damage, but blackbrush acacia grows slowly (Bozzo et al 1992, Reynolds et al 1992. Both shrub species are spinescent-armed with sharp-pointed woody outgrowths.…”

An approach to tree thinning to structure southern African savannas for long-term restoration from bush encroachment

“…Competitive interactions between the woody and herbaceous components of savannas, involving mainly available soil water as the primary determinant of production, have been reported worldwide (Australia: Walker et al, 1986Walker et al, , 1989Harrington and Johns, 1990;Scanlan and Burrows, 1990;North America: Scifres et al, 1982;Scifres, 1987;Archer et al, 1988;Bozzo et al, 1992;Haworth and McPherson, 1994; southern and east Africa: Donaldson and Kelk, 1970;Dye and Spear, 1982;Scholes, 1987;Belsky et al, 1989;Smit, 1994;Smit and Swart, 1994;Smit and Rethman, 1999;2000;Richter et al, 2001).…”

Structure of vegetation patches in northwestern Patagonia, Argentina

“…Forb species richness was greater during the first year after discing than on untreated areas in southern Texas (Bozzo et al 1992). Because herbaceous species diversity may temporarily increase, treatments such as discing and roller chopping may result in posttreatment plant communities that are temporarily greater in species diversity than nontreated communities (Fulbright 1996).…”