Nitrogen Inputs and Cycling in Ecosystems of the Western Cape Province of
Supported by the A.W. Mellon Foundation
United States PI:
Dr. Jason Neff, Geosciences Department, CU Boulder
Dr. Nichole Barger, Ecology and Evolutionary Biology, CU Boulder
South Africa Collaborating Scientist:
Dr. John Stockton, Department of Geological Sciences, University of Cape Town
In this project we outline a study of nitrogen (N) cycling across the diverse flora of the Western Cape province of South Africa. This region of South Africa has a remarkable diversity of floral assemblages that are arrayed across (and associated with) an equally diverse collection of geologic settings. We propose a study of nitrogen inputs and cycling that will be closely tied to an ongoing NRF funded study led by John Stockton of the University of Cape Town that is focused on understanding the role of geologic and geochemical variation in the control of floral composition in this region. This current project is oriented around the study of the inputs and cycling of macro and micronutrients (excluding N) in ecosystems that range from the Strandveld coastal ecosystems to the mountain Fynbos ecosystems of Table Mountain National Park. This existing set of sites and studies offers a remarkable opportunity to not only examine N cycling across a range of settings, but also to better understand the interaction between the N cycle and the cycling of other P and the micronutrients. In this project we will specifically focus on the response of N fixation to variation in soil nutrient status and marine aerosol N input into Western Cape Ecosystems. We expect to find increasing reliance on N fixation derived N in the Fynbos ecosystems compared to the coastal settings where marine aerosol inputs are higher. However, the extraordinary diversity of geochemical settings in this area (and the corresponding variation in vegetation cover) suggests the possibility that micronutrient and P availability may interact with, and potentially control, the biological fixation of N to these ecosystems. The combination of the proposed N studies and the ongoing geochemical and floristic opportunities offer a unique opportunity to examine the interactions between the major biogeochemical cycles and the role that these interactions play in structural biological communities.