Data from: Repeated clearing as a mechanism for savanna recovery following bush encroachment

Many savannas are experiencing increased cover of trees and shrubs,
resulting in reduced herbaceous productivity, shifts in savanna functional
structure, and potential reductions in ecotourism. Clearing woody plants
has been suggested as an effective management strategy to mitigate these
effects and restore these systems to an open state with higher rates of
grass production and herbivory. This study investigated the effectiveness
of repeated shrub clearing as a tool to mitigate bush encroachment in a
semi-arid savanna in Southern Africa. We present data from a 7-year
experiment in the Mthimkhulu Game Reserve bordering Kruger National Park,
South Africa. Colophospermum mopane stems and re-sprouting shoots
were basally cut 2-3 times per year (2015-2022) in 3 pairs of treatment
and control plots of 60 m x 60 m. We monitored changes in soil moisture,
grass biomass, and herbivore activity via dung counts. We assessed C.
mopane physiological responses to repeated cutting using non-structural
carbohydrates and stable water isotopes to infer changes to energy storage
and functional rooting depth, respectively. The cleared treatment had
higher soil moisture and grass biomass than the control treatment. Dung
counts showed impala and buffalo visited the cleared treatment more
frequently than the control treatment. Repeated cutting had limited
effects on C. mopane survival in the first 2-3 years after
initial clearing, but 80% of individuals were dead after 7 years.
Repeatedly cut C. mopane had lower belowground starch concentrations and
used water from shallower soil depths than C. mopane in control plots.
Synthesis and applications: Repeated cutting increased soil moisture
availability and grass biomass, and attracted charismatic grazing
herbivores. While more costly than once-off clearing methods, this
practice created more employment opportunities for a neighbouring rural
community. Transforming portions of the ecosystem to a grass-dominated
state may increase ecotourism potential through improved game viewing in
open systems.