The importance of nutrient hotspots for grazing ungulates in a Miombo ecosystem, Tanzania

PLoS One. 2020 Mar 30;15(3):e0230192. doi: 10.1371/journal.pone.0230192. eCollection 2020.

Abstract

While movement patterns of grazing ungulates are strongly dependent on forage quality their use of nutrient hotspots such as termite mounds or grazing lawns has rarely been quantified, especially in savanna ecosystems where soil-nutrient quality is low. Additionally, few experiments have been conducted to determine the role of termite mound- and grazing lawn-derived soils in improving forage quality in the field. We studied wild ungulate grazing activities around ten termite mounds, six grazing lawns and their respective control sites in a Miombo system of Issa Valley, western Tanzania, in the same system. We used indirect observations (i.e., dung, tracks) to identify seasonal and spatial variations in habitat use of various wild mammalian grazers. Grazer visitation rates were nine and three times higher on termite mounds and grazing lawns, respectively, compared to control sites. During the rainy season, termite mounds were more frequently used than grazing lawns while the latter were used more often during the dry season. In an additional pot experiment with soils derived from different areas, we found that Cynodon dactylon in termite mound-derived soils had twice as high Nitrogen and Phosphorous contents and biomass compared to grasses planted in grazing lawn soils and control site soils. We highlight that both termite mounds and grazing lawns play a significant role in influencing seasonal nutrient dynamics, forage nutrient quality, habitat selectivity, and, hence, grazing activities and movement patterns of wild ungulate grazers in savannas. We conclude that termite mounds and grazing lawns are important for habitat heterogeneity in otherwise nutrient-poor savanna systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biomass
  • Cynodon / chemistry*
  • Ecosystem
  • Feeding Behavior / physiology
  • Grassland
  • Isoptera / chemistry
  • Mammals
  • Nitrogen / chemistry
  • Nutrients / chemistry*
  • Phosphorus / chemistry
  • Plants / chemistry
  • Poaceae / chemistry*
  • Seasons
  • Soil / chemistry
  • Tanzania

Substances

  • Soil
  • Phosphorus
  • Nitrogen

Associated data

  • figshare/10.6084/m9.figshare.11940906.v1

Grants and funding

This research was funded by The German Academic Exchange Service (DAAD), the African Centre for Research, Agricultural advancement, Teaching Excellence and Sustainability (CREATES), and the Greater Mahale Ecosystem Research and Conservation Project (GMERC).Support for GMERC comes from the UCSD/Salk Center for Academic Research and Training in Anthropogeny (CARTA).