Controls on primary productivity in tropical dry forests

About the project

About the Project What nutrients limit primary production in tropical dry forest (TDF)? Without answering this question, we cannot predict how 40% of the world’s tropical forest will respond to elevated CO 2 , nitrogen deposition, or other forms of nutrient pollution. This knowledge gap also constrains our capacity to manage and restore TDF to meet climate mitigation targets. Since the seminal work of Walker and Syers in the 1970s, ecosystem ecologists have predicted that plant growth in temperate regions is limited by the availability of nitrogen (N), whereas productivity in the tropics is limited by the availability of phosphorus (P). This is because the younger, recently glaciated soils of higher-latitude ecosystems tend to be N-deprived, whereas the old, highly weathered soils that characterize many tropical forests are highly P-deficient. However, many TDF occur on soils that are not ancient or extensively weathered, yet rates of biological N fixation are also extremely high. This calls into question the identity of the nutrient(s) that might constrain forest growth in these systems. In this PhD project, you will analyse data from the world’s first and largest tropical dry forest fertilization experiment. Since 2015, N, P, or the combination of both have been added to replicate 25 x 25 m plots in a regenerating tropical dry forest in Northwest Costa Rica, and the growth of individual trees has been measured with dendrometers. You will also have the opportunity to explore micronutrient limitation of vegetation dynamics through greenhouse and shadehouse experiments, and may conduct additional field manipulations to explore micronutrient responses of adult trees. You will join the Waring Ecology Lab at Imperial College London, where we investigate how the ecology of plant and soil microbial communities influences the carbon cycle and its feedbacks on climate change. The PhD offers the opportunity for close collaboration with the Powers Lab at the University of Minnesota, and the chance to conduct research at a field station in northwest Costa Rica. This PhD opportunity will be funded through a competitive standard scholarship via Imperial College London’s Department of Life Sciences. For more information about this specific project opportunity, contact Bonnie Waring at b.waring@imperial.ac.uk

Research areas