Theme 1-2: Rangeland/Grassland Ecology--Poster Sessions
Description
Decomposition is a major determinant of terrestrial nutrient cycling and therefore an important regulator of ecosystem structure and function. It has been widely documented that large mammalian herbivores (LMH) act as a significant driver of changes to aboveground structure and modifications to edaphic properties. Little is known about the role of herbivory, and particularly the loss thereof, in mediating essential ecological processes in a herbivore-adapted system. The Nkuhlu exclosures, a large-scale, long-term exclusion experiment in the Kruger National Park, South Africa, provided an opportunity to explore the effects of herbivory and/or its long-term exclusion on decomposition and stabilisation of detrital plant material. An extended, site-specific version of the Tea Bag Index approach was used to quantify decomposition rate (k) and stabilisation factor (S) of standardised litter substrate. Two hundred and fifty tea bags (125 green and 125 rooibos tea bags) applied in a paired tea bag design were exposed to three herbivore treatments along the sodic zone of the Nkuhlu exclosures and removed after three months of incubation. Decomposition rates (k) were highest in the presence of LMH and lowest in their absence. Conversely, stabilisation factor (S) was significantly higher in treatments from which herbivores have been excluded for ~18 years. Our study provides evidence that LMH can influence essential ecological processes such as decomposition and stabilisation of detrital plant material. Moreover, results confirmed that ecosystems that evolved with herbivores, are sensitive to herbivore loss as it reduces decomposition rates of plant detritus and hence, decelerates ecosystem nutrient cycling.
Citation
Erasmus, L. L.; Van Coller, H.; Claassens, S.; and Siebert, F., "Decomposition Rates of Organic Material across Herbivore Treatments in a Nutrient-Rich Semi-Arid Sodic Savanna" (2022). IGC Proceedings (1993-2023). 10.
https://uknowledge.uky.edu/igc/24/1-2/10
Included in
Decomposition Rates of Organic Material across Herbivore Treatments in a Nutrient-Rich Semi-Arid Sodic Savanna
Decomposition is a major determinant of terrestrial nutrient cycling and therefore an important regulator of ecosystem structure and function. It has been widely documented that large mammalian herbivores (LMH) act as a significant driver of changes to aboveground structure and modifications to edaphic properties. Little is known about the role of herbivory, and particularly the loss thereof, in mediating essential ecological processes in a herbivore-adapted system. The Nkuhlu exclosures, a large-scale, long-term exclusion experiment in the Kruger National Park, South Africa, provided an opportunity to explore the effects of herbivory and/or its long-term exclusion on decomposition and stabilisation of detrital plant material. An extended, site-specific version of the Tea Bag Index approach was used to quantify decomposition rate (k) and stabilisation factor (S) of standardised litter substrate. Two hundred and fifty tea bags (125 green and 125 rooibos tea bags) applied in a paired tea bag design were exposed to three herbivore treatments along the sodic zone of the Nkuhlu exclosures and removed after three months of incubation. Decomposition rates (k) were highest in the presence of LMH and lowest in their absence. Conversely, stabilisation factor (S) was significantly higher in treatments from which herbivores have been excluded for ~18 years. Our study provides evidence that LMH can influence essential ecological processes such as decomposition and stabilisation of detrital plant material. Moreover, results confirmed that ecosystems that evolved with herbivores, are sensitive to herbivore loss as it reduces decomposition rates of plant detritus and hence, decelerates ecosystem nutrient cycling.
