Enough is enough: The effects of symbiotic ant abundance on herbivory, growth, and reproduction in an African acacia

Understanding how cooperative interactions evolve and persist remains a central challenge in biology. Many mutualisms are thought to be maintained by ‘‘partner fidelity feedback,’’ in which each partner bases their investment on the benefits they receive. Yet, we know little about how benefits change as mutualists vary their investment, which is critical to understanding the […]

Interspecific and temporal variation of condensed tannins and cyanide concentrations in potential dietary sources of extralimital giraffes (Giraffa camelopardalis) in the Karoo

During 2016 and 2018 four giraffe (Giraffa camelopardalis) mortalities occurred in the Karoo potentially caused by acute hydrogen cyanide poisoning. Plants have various defence mechanisms to protect themselves against herbivory, including the production of secondary metabolites such as condensed tannins and hydrogen cyanide. This study quantified condensed tannin and hydrogen cyanide production in selected Karoo […]

Thorns as induced defenses: experimental evidence

We report evidence from controlled experiments that long straight thorns deter herbivory by browsers. Cut branches of three woody species that had their thorns removed suffered significantly greater herbivory by a tethered goat than did paired intact branches. Branches on living Acacia seyal plants that had their thorns removed suffered significantly greater herbivory by a […]

Delayed effects of fire on habitat use by large herbivores in Acacia drepanolobium savanna

Fire is frequently used as a wildlife management tool in savanna habitats (Trollope, 1982). Burning stimulates sprouting of plants (Vesey-Fitzgerald, 1971), improving forage quality (Komarek, 1967; Dorgeloh, 1999). Several studies have supported quantitatively what has been well known by managers for some time, namely that ungulates are attracted by resprouting vegetation in recently burned areas […]

Effects of simulated shoot and leaf herbivory on vegetative growth and plant defense in Acacia drepanolobium

Plants have considerable ability to respond to herbivory, both with (above-ground) regrowth and with increased defense. We simulated both leaf and shoot herbivory in controlled, replicated experiments on individuals of Acacia drepanolobium in Laikipia, Kenya. These experiments were carried out on individuals that had experienced different, experimentally controlled histories of large mammalian herbivory. Both forms […]

Browsing-induced Effects on Leaf Litter Quality and Decomposition in a Southern African Savanna

We investigated the linkages between leaf litter quality and decomposability in a savanna plant community dominated by palatable-spinescent tree species. We measured: (1) leaf litter decomposability across five woody species that differ in leaf chemistry; (2) mass decomposition, nitrogen (N); and carbon (C) dynamics in leaf litter of a staple browse species (Acacia nigrescens) as […]

Shoot characteristics of Acacia tortilis (Forsk.) in wildlife and rangeland habitats of Botswana

Length, branch production, orientation, spinescence and biomass were measured for current shoots of Acacia tortilis shrubs in a range of habitats in Botswana. All shoot characteristics varied between individuals and between habitats with longer, less spinescent shoots produced in the habitat recently protected from wildlife. Biomass allocated to woody material increased with shoot length at […]