DOI: 10.5061/dryad.h18931zsf
title: Protecting the resource: an assessment of mitigation methods used to protect large trees from African elephant impact in a savanna system

description: African elephants (Loxodonta africana) can alter the structural components
 of savanna ecosystems, often through the reduction of the large tree
 (&gt;5 m height) cover component. Elephant impact can be amplified in
 small, protected areas, or areas where water is readily available to
 elephants. One management option is to protect large trees directly using
 applied mitigation methods to limit elephant impact. In this paper, we
 assessed and compared the effectiveness and logistical requirements of
 four mitigation methods that have been applied to protect large trees from
 elephant impact in South Africa’s Greater Kruger National Park - namely
 African honeybees (Apis mellifera scutellata) in beehives; creosote oil in
 glass jars, concrete pyramids arranged in circles around trees, as well as
 wire-netting the trees’ main stems. For each method, elephant impact
 levels and tree mortality rates were measured over a 2–5-year period
 depending on the method in use. Sample sizes ranged from 43 to 59 trees
 per mitigation method, with a comparable control, which was a tree of the
 same species and morphological dimensions but lacking any mitigation
 application. Beehives were the most effective method at reducing tree
 loss, significantly reducing tree mortality from 34% (6.8%/year) in
 control trees to only 10% (2%/year) over the five-year experimental
 period. However, beehives were the most expensive method to apply to a
 tree, although this cost can be compensated through honey sales. Concrete
 pyramids reduced tree loss when the combined pyramid radius was
 &gt;1.5 m in length, whilst wire-netting was effective against
 bark-stripping by elephants but was still vulnerable to heavier forms of
 impact such as uprooting and stem snapping. Creosote jars did not prevent
 elephants from impacting treated trees. Our results provide managers with
 a toolkit for protecting large trees against elephant impact, commenting
 on both the efficacy and the logistical constraints for each method.
description: # Protecting the resource: an assessment of mitigation methods used to
 protect large trees from African elephant impact in a savanna system In
 this study, we assess the effectiveness of four mitigation methods that
 have been used to protect marula (*Sclerocarya birrea*) trees from African
 elephant (*Loxodonta africana*) impact in the Associated Private Nature
 Reserves (APNR) in South Africa. The four mitigation methods included
 beehives, creosote jars, concrete pyramids and wire-netting. Each
 'treated' tree was compared with control (no protection) trees,
 with the levels of impact assessed and compared between the method and
 control trees. ## Description of the data and file structure The datasets
 are divided into the following sections: **1) Elephant impact scores**
 Impact scores were measured at the start and end of each method's
 experiment. Impact scores were assessed according to the following
 assessment table: **Table 1.** Elephant impact scoring system for impact
 on large trees, as defined by Walker (1976) and modified by Greyling
 (2004). | Impact-type | Impact-type severity classes | | ----------- |
 ---------------------------- | | 1 | 2 | | Bark-stripping | No impact | |
 Primary branch breakage | No impact | | Uprooting | No impact | | Main
 stem snapping | No impact | | Secondary branch breakage | No impact since
 baseline assessment | Time was measured as 0 (Project start) and 1
 (Project end). This data was used to assess how each method protect the
 trees against various forms of elephant impact. Greyling, M. D. 2004. Sex
 and age related distinctions in the feeding ecology of the African
 elephant, *Loxodonta africana*. PhD Thesis, University of the
 Witwatersrand, Johannesburg, South Africa. Walker, B. H. 1976. An approach
 to the monitoring of changes in the composition and utilization of
 woodland and savanna vegetation. South African Journal of Wildlife
 Research – 6: 1-32. **2) Survival analyses** Survival analyses data
 includes the method name (*Method*), whether it is a control or treated
 tree (*Treatment*), the number of years that the tree survived (*Time*)
 and whether the tree survived (0) or was killed (1) (*Status*). This data
 was used to assess the effectiveness of each method at prolonging the
 persistence of marula trees in the APNR. Each method was compared against
 its control trees. **3) Regression** The regression data was used to
 assess how tree survival was affected by the type of mitigation, tree
 height (m), as well as stem diameter (cm). The tree height and stem
 diameter values have been logged. Mortality is recorded as 0 (tree alive)
 or 1 (tree dead). The Excel file contains a metadata tab for each data
 tab, complete with variable descriptions. ## Sharing/Access information
 Further information regarding the dataset can be obtained by contacting
 the lead author (Robin Cook; robincook@elephantsalive.org) or the Director
 of Elephants Alive (Dr. Michelle Henley;
 michelephant@savetheelephants.org). ## Code/Software All statistical
 analyses were conduced in R-studio. The following R-packages were used for
 the survival analyses: *survival* package, Therneau 2022 Therneau, T. T.
 2022. survival: Survival Analysis. R package version 3.4-0.