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Herbivore-vegetation interactions in savanna: importance of fluxes and stoichimetry of nitrogen and phosphorus

English title Herbivore-vegetation interactions in savanna: importance of fluxes and stoichimetry of nitrogen and phosphorus
Applicant Edwards Peter J.
Number 120305
Funding scheme Project funding (Div. I-III)
Research institution Institut für Integrative Biologie Departement Umweltwissenschaften ETHZ
Institution of higher education ETH Zurich - ETHZ
Main discipline Ecology
Start/End 01.09.2008 - 31.08.2011
Approved amount 237'384.00
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Keywords (9)

savanna; vegetation; acacia; ecological stoichiometry; giraffe; grazers; nutrient cycling; spatial ecology; wildebeest

Lay Summary (English)

Lead
Lay summary
We will study how different herbivore species in an African savanna influence the spatial distribution and turnover of nutrients, and how these processes affect competition between grasses and Acacia trees. The study area is the Saadani National Park in Tanzania.Plant nutritional quality in savanna ecosystems is regulated by complex interactions between herbivores, nutrients and fire. Particularly important are feedback mechanisms between herbivores and plants. There is large variation among herbivores (e.g. giraffe vs. wildebeest) in tissue nitrogen (N) and phosphorus (P) concentrations of their food, which in turn has a considerable effect upon N and P concentrations in their dung. Also, herbivores vary widely in their spatial patterns of feeding and dung excretion.Our aim is an improved understanding of how different herbivore species influence the spatial distribution and turnover of N and P in savanna ecosystems, and thereby affect the structure and species composition of vegetation. Our research will contribute to a better understanding of how grazing ecosystems function, and how different herbivores affect N and P cycling and vegetation composition. Given that two of the grazers, wildebeest and zebra, are not native in our study region, it may also reveal whether the ecosystem maintains itself, or whether it will develop in such a way that it eventually becomes unsuitable for these animals. This type of information will be valuable for managing Saadani National Park, as well as in attempts to recreate grazing ecosystems in other savanna areas that have lost their wildlife.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Structure and biomass along an Acacia zanzibarica woodland-savanna gradient in a former ranching area in coastal Tanzania
Cochard R, Edwards PJ (2011), Structure and biomass along an Acacia zanzibarica woodland-savanna gradient in a former ranching area in coastal Tanzania, in JOURNAL OF VEGETATION SCIENCE, 22(3), 475-489.
Tree dieback and regeneration in secondary Acacia zanzibarica woodlands on an abandoned cattle ranch in coastal Tanzania
Cochard R, Edwards PJ (2011), Tree dieback and regeneration in secondary Acacia zanzibarica woodlands on an abandoned cattle ranch in coastal Tanzania, in JOURNAL OF VEGETATION SCIENCE, 22(3), 490-502.
N and P Cycling in Tanzanian Humid Savanna: Influence of Herbivores, Fire, and N-2-Fixation
Cech PG, Venterink HO, Edwards PJ (2010), N and P Cycling in Tanzanian Humid Savanna: Influence of Herbivores, Fire, and N-2-Fixation, in ECOSYSTEMS, 13(7), 1079-1096.
Why is Abundance of Herbaceous Legumes Low in African Savanna? A Test with Two Model Species
Cech PG, Edwards PJ, Venterink HO (2010), Why is Abundance of Herbaceous Legumes Low in African Savanna? A Test with Two Model Species, in BIOTROPICA, 42(5), 580-589.
Effects of herbivory, fire and N-2-fixation on nutrient limitation in a humid African savanna
Cech PG, Kuster T, Edwards PJ, Venterink HO (2008), Effects of herbivory, fire and N-2-fixation on nutrient limitation in a humid African savanna, in ECOSYSTEMS, 11(6), 991-1004.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Association of Tropical Ecology 21.02.2011 Frankfurt
Tropentag 14.09.2010 Zurich


Associated projects

Number Title Start Funding scheme
105778 Recolonization of a savanna ecosystem by ungulate herbivores after abandonment of ranching 01.01.2005 Project funding (Div. I-III)
122590 Herbivore-vegetation interactions in oligothrophic savanna: exploring the limits for grazers to drive landscape dynamics 01.11.2008 Project funding (Div. I-III)

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