title: An overview of nitrogen cycling in a semiarid savanna: some implications for management and conservation in a large African park.
abstract: Nitrogen (N) is a major control on primary productivity and hence on the productivity and diversity of secondary producers and consumers. As such, ecosystem structure and function cannot be understood without a comprehensive understanding of N cycling and dynamics. This overview describes the factors that govern N distribution and dynamics and the consequences that variable N dynamics have for structure, function and thresholds of potential concern (TPCs) for management of a semiarid southern African savanna. We focus on the Kruger National Park (KNP), a relatively intact savanna, noted for its wide array of animal and plant species and a prized tourist destination. KNP's large size ensures integrity of most ecosystem processes and much can be learned about drivers of ecosystem structure and function using this park as a baseline. Our overview shows that large scale variability in substrates exists, but do not necessarily have predictable consequences for N cycling. The impact of major drivers such as fire is complex; at a landscape scale little differences in stocks and cycling were found, though at a smaller scale changes in woody cover can lead to concomitant changes in total N. Contrasting impacts of browsers and grazers on N turnover has been recorded. Due to the complexity of this ecosystem, we conclude that it will be complicated to draw up TPCs for most transformations and pools involved with the N cycle. However, we highlight in which cases the development of TPCs will be possible.
authors: School of Natural Resource Management, Nelson Mandela Metropolitan University, P/Bag 6531 Saasveld, George, 6530, Western Cape, South Africa. Corli.Coetsee@nmmu.ac.za
authors: Corli
authors: C
authors: Coetsee
authors: Shayne
authors: S
authors: Jacobs
authors: Navashni
authors: N
authors: Govender
mesh_terms: D000353:Africa, Southern; D000818:Animals; D003247:Conservation of Natural Resources; D005390:Fires; D060434:Herbivory; D009584:Nitrogen / Q000032:analysis; D058458:Nitrogen Cycle; D018515:Plant Leaves / Q000737:chemistry; D010944:Plants; D012987:Soil / Q000032:analysis
chemical_list: D012987:Soil; D009584:Nitrogen