Mammalian herbivore movement into drought refugia has cascading effects on savanna insect communities

Trisos, Matthew Owen; Parr, Catherine; Davies, Andrew B.; Leitner, Monica; February, Edmund C.

doi:10.1111/1365-2656.13494

Cited by 2 publications

(2 citation statements)

References 70 publications

(98 reference statements)

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“…Since climate and sampling time (i.e., season) does not affect the abundance and richness of arthropods sampled at the savanna and grasslands of sub-Saharan Africa [64,65], plant diversity, stocking rates and grazing intensities could be associated with the varying response of arthropods at different exclosures of KNP [8,10,23,26,33,46,47,[65][66][67]. Therefore, mammal activity and heterogeneity of plants needs to be understood and correlated with assemblages of arthropods to ascertain the direct and indirect impact of mammal grazing on the abundance, species richness and composition of arthropods at KNP.…”

Section: Plos Onementioning

confidence: 99%

“…Gradual decline in the number of grazers per unit area was attributed to poaching, predation, disease, climate change and culling during seasons where food resource is inadequate at the protected nature reserve [22][23][24][25]. Change in the number of grazers influences heterogeneity of landscapes, abundance, diversity and composition of plants, mammals, birds and arthropods [1,[26][27][28]. Thus, the topdown pressures inflicted by grazers should be thoroughly understood to encourage conservation of species in the ecosystem.…”

Section: Introductionmentioning

confidence: 99%

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Long-term mammal herbivory on arthropod assemblages at Kruger National Park, South Africa

2023

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Protected savannas are essential reserves for biological diversity, including endangered arthropod species, however, extreme grazing by mammals has cascading impacts on the communities and disrupts the functioning of these ecosystems globally. The current study assessed the abundance, species richness and composition of arthropods at the long-term grazing exclosures of Kruger National Park, South Africa. Pitfall traps and active searches were used to sample arthropods at the ungrazed, moderately, and heavily grazed exclosures. We found that Hymenoptera, Coleoptera, Diptera and Araneae were the most abundant orders of arthropods sampled. The abundance of multi-taxon, Diptera and Hymenoptera was significantly different between exclosures. In contrast, Coleoptera had high numbers of morphospecies compared to Hymenoptera, Araneae and Diptera. Species richness for multi-taxon, Diptera and Hymenoptera was significantly high at the heavily grazed compared to moderately grazed and ungrazed exclosures. Up to 22.2%, 41.2%, and 44.4% of the morphospecies were unique to the ungrazed, moderately and heavily grazed exclosures, respectively. A high proportion of morphospecies shared between exclosures were Coleoptera (41.0%) and Hymenoptera (38.5%) compared to Diptera and Araneae with less than 5% recorded across exclosures. Thus, morphospecies within the least abundant orders, namely Diptera and Araneae, were represented by singletons that were unique to particular exclosures compared to the most abundant arthropod orders (e.g., Coleoptera and Hymenoptera). We conclude that long-term mammal grazing enhances species richness and niche composition together with sparse and unique arthropods in the protected savannas. Therefore, managed grazing regimes can serve as a tool for maintaining the integrity of the protected savannas.

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