Grass and ground dwelling beetle community responses to holistic and wildlife grazing management using a cross-fence comparison in Western Kalahari rangeland, Namibia ⋆ Savory Institute

Science Article

Grass and ground dwelling beetle community responses to holistic and wildlife grazing management using a cross-fence comparison in Western Kalahari rangeland, Namibia

Reinhard, J.E., Geissler, K. & Blaum, N. Grass and ground dwelling beetle community responses to holistic and wildlife grazing management using a cross-fence comparison in Western Kalahari rangeland, Namibia. J Insect Conserv (2022). https://doi.org/10.1007/s10841-022-00410-6

Key Takeaways

In this paper, researchers compared the impact of Holistic Management to wildlife grazing on grass and ground-dwelling beetle species diversity on neighboring farms in Namibian rangeland.
Despite rotational grazing, the typical form of management in southern Africa, land degradation is still seen in the form of bush encroachment. To resolve this, there has been a call for an adaptive grazing management strategy, i.e. Holistic Management, to restore these degraded rangelands and conserve biodiversity. Others advocate for natural wildlife management in the form of “conservancies,” requiring little in terms of infrastructure (fencing, watering, etc.) and allowing for income generation through ecotourism, safari, hunting, and meat production.
To compare the two forms of management, ground beetles were chosen as they have been shown “to be good ecological indicators for biodiversity in many ecosystems” and “are sensitive to changes in structural diversity and small scale habitat changes, easy to sample and extremely species rich in arid systems.”
Beetle populations were studied during the summer growing season, the beginning of winter, and the non-growing season. Vegetation was also surveyed, including bare ground, total vegetation and litter, number of grass species, and percentage cover for each species.
Results showed 16 grass species, all of which were found on the Holistic Management site and 6 of which were found on the wildlife conservancy. The 3 grass species with a Climax successional status were only found on the Holistic Management site.
For beetle populations, 220 specimens of 33 species (18 unique) were found on the holistically managed site while 309 specimens of only 20 species (6 unique) were found on the wildlife conservancy, showing that while the conservancy had a greater total number of beetles, it also had less diversity.
Overall, the holistically managed livestock operation demonstrated greater species richness and biodiversity for both vegetation and beetle populations. While species of beetle differed across the two sites, indicating that Holistic Management doesn’t necessarily “mimick wildlife grazing” as some claim, it provides a superior ecological impact nonetheless.

Summary

Savannahs are often branded by livestock grazing with resulting land degradation. Holistic management of livestock was proposed to contribute to biodiversity conservation by simulating native wildlife grazing behaviour. This study attempts the comparison of the impact of a holistic management regime to a wildlife grazing management regime on grass and ground-dwelling beetle species diversity on neighboring farms in Namibian rangeland. Results show that the response of biodiversity in species richness and composition to holistic management of livestock differs substantially from wildlife grazing with a positive impact. From a total of 39 identified species of ground-dwelling beetles (Coleoptera: Tenebrionidae, Carabidae) from 29 genera, eight species were found to be indicators for holistic management of livestock and three were found to be indicators for wildlife grazed rangeland. Observations suggest that holistic management of livestock may contribute to biodiversity conservation, but the differential effect of grazing management on species assemblages suggests that livestock grazing cannot replace native wildlife herbivory.