Rolling pits of Hartmann's mountain zebra (Zebra equus hartmannae) increase vegetation diversity and landscape heterogeneity in the Pre‐Namib. Issue 19 (25th August 2021)

• Record Type: Journal Article
• Authors: Wagner, Thomas C.; Uiseb, Kenneth; Fischer, Christina
• Is Part Of: Ecology and evolution. Volume 11:Issue 19(2021)
• Page Start: 13036
• Page End: 13051
• Publication Date: 2021-08-25
• Subjects: bioturbation -- ecosystem engineer -- microsite -- Namibia -- savanna -- trophic cascade -- wallow; Ecology -- Periodicals; Evolution -- Periodicals; 577.05
• DOI: 10.1002/ece3.7983
• Languages: English
• ISSNs: 2045-7758

Abstract

Abstract: Microsites created by soil‐disturbing animals are important landscape elements in arid environments. In the Pre‐Namib, dust‐bathing behavior of the near‐endemic Hartmann's mountain zebra creates unique rolling pits that persist in the landscape. However, the ecohydrological characteristics and the effects of those microsites on the vegetation and on organisms of higher trophic levels are still unknown. In our study, we characterized the soil grain size composition and infiltration properties of rolling pits and reference sites and recorded vegetation and arthropod assemblages during the rainy season of five consecutive years with different amounts of seasonal rainfall. We further used the excess green vegetation index derived from drone imagery to demonstrate the different green up and wilting of pits and references after a rainfall event. In contrast to the surrounding grassland, rolling pits had finer soil with higher nutrient content, collected runoff, showed a higher infiltration, and kept soil moisture longer. Vegetation in the rolling pits was denser, dominated by annual forbs and remained green for longer periods. The denser vegetation resulted in a slightly higher activity density of herbivorous arthropods, which in turn increased the activity density of omnivorous and predatory arthropods. In times of drought, the rolling pits could act as safe sites and refuges for forbs and arthropods. With their rolling pits, Hartmann's mountain zebras act as ecosystem engineers, contributing to the diversity of forb communities and heterogeneity of the landscape in the Pre‐Namib. Abstract : The dust‐bathing behavior of the Hartmann's mountain zebra creates unique rolling‐pits that persist in the landscape. In contrast to the surrounding grassland, the rolling‐pits have finer soil with higher nutrient content, collect run‐off, show a higher infiltration and keep soil moisture longer. Vegetation in the rolling‐pits is denser, dominated by annual forbs and remains green for longer periods. This denser vegetation results in a slightly higher activity density of herbivorous arthropods, which in turn increases the activity density of omnivorous and predatory arthropods. In times of drought, the rolling‐pits act as safe‐sites and refuges for forbs and arthropods. With their rolling‐pits Hartmann's mountain zebras act as ecosystem engineers, contributing to the diversity of forb communities and heterogeneity of the landscape in the Pre‐Namib. (Image credit: Theo Allofs, https://www.naturefineart.com ).