Management approaches of conservation areas: Differences in woody vegetation structure in a private and a national reserve

• We compare 3D woody vegetation structure in a private and statutory protected area.
• Each area had different succession timelines from cattle ranching to conservation.
• Differences below 3 m are due to bush-clearing and cattle ranching legacy.
• Differences above 6 m are a result of presence of megaherbivore densities.
• Areas can be successfully converted from cattle ranching to conservation.

Management approaches taken in protected areas will affect their ability and effectiveness to conserve biodiversity. MalaMala (a concession within Sabi Sand Wildtuin, a private game reserve), and an adjacent area in the Kruger National Park (Kruger, statutory protected area) in South Africa provide a comparison of different types of conservation management. We measured three-dimensional woody vegetation structure, as an integral component of biodiversity, across 6200 ha in the two reserves using a LiDAR (Light-Detection-and-Ranging) sensor. We compared how different management approaches in the two reserves affected woody structural diversity. Vertical canopy diversity was measured using: i) percent cover of woody vegetation extracted from LiDAR canopy height models, ii) a volumetric pixel (voxel) approach to extract 3D vertical canopy-height profiles; and iii) horizontal diversity using landscape metrics. MalaMala had higher vegetation density than Kruger in the < 3 m (2.5 times) and > 6 m (2.7 times) height classes. This vegetation was in the form of larger, more cohesive patches as a result of the legacy of previous land-use (cattle ranching) and current management practices (bush clearing) and the recent increase in megaherbivores. Length of exposure to, and recent higher densities of, megaherbivores (particularly elephants) has altered the density of tall trees in the two reserves, thus affecting structural heterogeneity and associated habitat options for small-bodied vertebrates. These differences in vegetation structure are exacerbated by current management practices (e.g. bush-clearing and fire regime), with potential implications for faunal biodiversity conservation across a wide range of scales.