PARENT SESSION
Contributed Oral Session 51: Arid Land Management, Vegetation, and Nutrient Dynamics
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 522 A, Level 5, Palais des congrès de Montréal
Differences in nutrient limitation among tree species and riparian areas in Kruger National Park, South Africa.
Hicks, Caitlin*,1, Cadnesso, Mary2, Pickett, Steward1, 1 Institute of Ecosystem Studies, Millbrook, NY2 Yale University, New Haven, CT
ABSTRACT- In the savanna systems of Kruger National Park, South Africa, riparian areas are possible hot spots of nutrients compared to the adjacent uplands. There are several types of riparian areas, which are located along mainstem rivers or tributaries and on top of basalt or granite bedrock. The ability of the riparian zone to act as a nutrient hot spot may differ among these heterogeneous riparian types. We compared the foliar nutrient ratios (C:N, C:P, and N:P) of 10 ubiquitous woody species in four types of riparian sites and two types of upland sites. To investigate nutrient limitations, we used the documented terrestrial threshold of 33 for N:P ratios, above which there is possible P-limitation and below which there is possible N-limitation. When averaged across sites, the within-species variation of the nutrient ratios was low. However, the between-species variation of nutrient ratios was high with some species seemingly N-limited, while others were seemingly P-limited. Despite the large differences among species, when the nutrient ratios of all species were averaged together by site, there were significant differences in the mean nutrient ratios between locations. Both upland sites and granite tributary sites had N:P ratios less than 33, suggesting N-limitation, while all mainstem sites had N:P ratios greater than 33, suggesting P-limitation. This information can indicate how the different riparian areas of Kruger National Park may mediate the flow of nutrients between the rivers and the uplands.
Key words: savanna, riparian, nutrient limitation, woody vegetation