Original Research
Large herbivore population performance and climate in a South African semi-arid savanna
Submitted: 08 March 2011 | Published: 08 February 2012
About the author(s)
Armin H. Seydack, Scientific Services, Garden Route National Park, South African National Parks, South AfricaCornelia C. Grant, Scientific Services, Kruger National Park, South African National Parks, South Africa
Izak P. Smit, Scientific Services, Kruger National Park, South African National Parks, South Africa
Wessel J. Vermeulen, Scientific Services, Garden Route National Park, South African National Parks, South Africa
Johan Baard, Scientific Services, Garden Route National Park, South African National Parks, South Africa
Nick Zambatis, Scientific Services, Kruger National Park, South African National Parks, South Africa
Abstract
Interpretation according to a climate–vegetation response model suggested that acclimation of forage plants to increasing temperature had resulted in temperature-enhanced plant productivity, initially increasing food availability and supporting transient synchronous increases in population abundance of both blue wildebeest and zebra, and selective grazers. As acclimation of plants to concurrently rising minimum (nocturnal) temperature (Tmin) took effect, adjustments in metabolic functionality occurred involving accelerated growth activity at the cost of storage-based metabolism. Growth-linked nitrogen dilution and reduced carbon-nutrient quality of forage then resulted in phases of subsequently declining herbivore populations. Over the long term (1910–2010), progressive plant functionality shifts towards accelerated metabolic growth rather than storage priority occurred in response to Tmin rising faster than maximum temperature (Tmax), thereby cumulatively compromising the carbon-nutrient quality of forage, a key resource for selective grazers.
The results of analyses thus revealed consistency between herbivore population trends and levels of forage quantity and quality congruent with expected plant metabolic responses to climate effects. Thus, according to the climate-vegetation response model, climate effects were implicated as the ultimate cause of large herbivore population performance in space and over time.
Conservation implications: In its broadest sense, the objective of this study was to contribute towards the enhanced understanding of landscape-scale functioning of savanna systems with regard to the interplay between climate, vegetation and herbivore population dynamics.
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Crossref Citations
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Journal of Biological Systems vol: 24 issue: 04 first page: 495 year: 2016
doi: 10.1142/S021833901650025X