Inter- and intra-plant variations in nitrogen, tannins and shoot growth of Sclerocarya birrea browsed by elephants Peter F. Scogings • Robert W. Taylor • David Ward Received: 23 March 2011 / Accepted: 14 October 2011 / Published online: 1 November 2011 Ó Springer Science+Business Media B.V. 2011 Abstract Impacts of elephants (Loxodonta africana africana) on woody vegetation has attracted substan- tial attention for decades, but plant-level responses remain a gap in the understanding of savanna ecology. Marula (Sclerocarya birrea caffra) forms an important part of elephant diets. We investigated the relation- ships between browsing intensity and shoot/leaf size, nitrogen (N) and condensed tannin (CT) concentra- tions in upper and lower canopies of male and female marula individuals in Hluhluwe-iMfolozi Park, South Africa. Browsing intensity (54%) did not differ between sexes, suggesting no preference by elephants for either sex. Females had higher [CT] than males and tannin decreased with increasing browsing intensity in both sexes. In lightly or moderately browsed trees, [CT] was controlled by unmeasured factors such that within-tree impacts of browsing were more variable in lightly/moderately browsed than heavily browsed trees. There was little change in [N] up to *60% browsing intensity, but [N] increased dramatically at higher intensity. Shoots and leaves on broken branches in the lower canopy were larger (2.5 and 1.2 times, respectively) than those on unbroken branches in either upper or lower canopies. Chemical responses were systemic and potentially influence browsing among trees, while growth responses were strongly localised and potentially influence browsing within trees. Although marula trees are able to compensate vigorously for browsing at the scale of individual organs, trees may become progressively carbon-defi- cient and have their lives shortened if total plant growth is negatively affected by chronic browsing, e.g. near permanent water. Keywords Browsing lawns Á Compensatory growth Á Herbivory Á Induced responses Á Plant defence Á Specific leaf area Introduction Elephants (Loxodonta africana africana) are impor- tant non-ruminants that consume woody plants in African savannas. Elephant impacts have attracted attention for many decades (Kerley et al. 2008), but the focus of attention has been almost exclusively at scales of populations and communities of plants. Compared with the range of studies involving ruminant impacts, the paucity of studies on plant-level responses to elephants remains a critical gap in the body of fundamental knowledge of savanna ecology. Long- term severe browsing by elephants is reported to P. F. Scogings (&) Department of Agriculture, University of Zululand, Private Bag X1001, KwaDlangezwa 3886, South Africa e-mail: pscoging@pan.uzulu.ac.za R. W. Taylor Á D. Ward School of Biological and Conservation Sciences, University of KwaZulu-Natal, Scottsville 3209, South Africa 123 Plant Ecol (2012) 213:483–491 DOI 10.1007/s11258-011-9996-x