A comparative assessment of the contribution of two different models for clearing invasive alien plants using grazing regimes in the Eastern Cape, South Africa

Abstract

Invasive alien plants (IAPs) compromise the productive capability of a land parcel from both an economic and a biodiversity perspective. Given the magnitude of degradation and the benefits of landscape-scale restoration, a unified approach among stakeholders is required to upscale restoration efforts. Seeking such an approach, we compare the efficiencies of two restoration and land use models for the period 2014–2016. Model A is characterised by both mechanical and bioturbation as methods to control the IAPs combined with short duration, high-density rotational grazing. Model B uses mechanical and chemical methods to control IAPs, as well as a mixed rotational rest grazing system. We found that Model B’s unit cost was 47% higher than that of Model A (R13 747, compared with R9 327 ha⁻¹). Model B is also less efficient with respect to the use of time and labour required to clear a hectare. We also note that seeking to simultaneously achieve dual objectives (e.g. ecological and social) using a single instrument, such as clearing IAPs, violates Tinbergen’s Golden Rule in Public Finance. By seeking efficiency on a single objective, e.g. with respect to ecological indicators, restoration will yield more benefits and impact more people for longer.