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The architecture of shrubs after defoliation and the subsequent feeding behavior of browsers


  • S. M. Cooper,

  • M. K. Owens,

  • D. E. Spalinger,

  • T. F. Ginnett

S. M. Cooper and M. K. Owens, Texas Agric. Exp. Station, Texas A&M Univ. System, 1619 Garner Field Road, Uvalde, TX 78801, USA. ( – D. E. Spalinger, Dept of Biol. Sci., Univ. of Alaska – Anchorage, 3211 Providence Drive, Anchorage, AK 99508, USA. – T. F. Ginnett, College of Natural Resources, Univ. of Wisconsin – Stevens Point, Stevens Point, WI 54481, USA.


We examined regrowth architecture of 4 species of savanna shrubs following 4 levels of defoliation. Defoliation had little effect on the regrowth architecture of honey mesquite (Prosopis glandulosa), which is rarely browsed by mammalian herbivores. The 3 acacia species (Acacia berlandieri, A. greggii, A. schaffneri) responded to defoliation by increasing leaf and spine density on the regrowth branches, but spine length and branching architecture remained unchanged. Only A. greggii, which is a preferred food plant of many browsers, exhibited an increase in the number and length of current annual growth branches in response to defoliation. The changes in plant architecture due to defoliation had little effect on the subsequent feeding behavior of captive white-tailed deer (Odocoileus virginianus). Food intake rate of the deer was most strongly related to internode distance, a parameter not significantly altered by defoliation. This suggests that the architectural responses of these shrubs to defoliation may not provide increased defense against browsing by co-evolved mammals.