Head of Group: Dr Andrew Tanentzap
We study how disturbances alter the functioning and biodiversity of the world's ecosystems in order to generate solutions for mitigating the impacts of global change. We focus on plants and their interactions with microbes, animals, and biogeochemical processes in terrestrial and freshwater systems. Our aim is to generate solutions for complex social, economic and environmental challenges, such as food security and the provision of ecosystem services, by developing predictive models to inform policy and management interventions. Currently, our work is: (i) identifying terrestrial controls over the functioning of aquatic ecosystems; and (ii) testing how evolutionary history influences the responses of ecosystems to disturbances. We are also engaged in other projects at the interface of conservation science and ecology, particularly in the agri-environment.
Current projects include:
Boreal regions hold upwards of 60% of the planet’s useable freshwater, but anthropogenic activities are dramatically altering these landscapes. Increasingly, local watersheds are seen as critical controls of aquatic ecosystems, spurred by the discovery that pathways of energy mobilization through lake food webs rely on the quantity and quality of organic matter originating from terrestrial vegetation. But a pressing question is how will the delivery of key ecosystem services provided by aquatic ecosystems, such as clean drinking water and productive fish populations, change as nutrient exports from terrestrial catchments are altered by anthropogenic activities.
We are using gradients in forest cover and large field experiments to test whether disturbances that remove terrestrial plant biomass will reduce the quantity and quality of organic matter inputs into freshwater, and thereby dampen the productivity of aquatic food webs. We believe that microbes are the gate keepers to higher energy mobilization in these systems and so are focusing on their interactions with phytoplankton for macronutrients. We are also using state-of-the-art fluorescent spectroscopy techniques to quantify the quality of organic matter emanating from different plant communities and relating this to the downstream consequences for ecosystem functioning.
Phylogenetic trait-based approaches to biogeography
We are interested in how patterns of biodiversity through geological time, and their responses to disturbances, are an outcome of evolutionary processes acting upon physiological and morphological traits. We are using large-scale vegetation surveys and controlled experiments to reconstruct the evolution of flooding and drought tolerance in wetland and woody plants so as to predict the responses of species to water stress. Recently, we have become interested in linking traits to patterns of gene expression to generate molecular mechanisms for explaining species distributions. Some of our other work is testing the consequences of megafaunal extinctions for trait distributions and tree regeneration in New Zealand forests.
Priority effects in explaining plant diversification
Identifying the processes underlying the origins of biodiversity is a central question in ecology and evolution. A widely-noted but poorly understood pattern is that the diversification of plant species on islands varies greatly, even among closely related lineages that evolved under similar conditions. Alongside Prof Bill Lee (Auckland, Landcare Research) , Dr Peter Heenan (Landcare Research), and Dr Tad Fukami (Stanford), we are part of a three-year Royal Society of New Zealand Marsden Project that aims to test whether colonization order drives the evolution of species richness within clades of alpine plants, and how the strength of these relationships are shaped by environmental and disturbance gradients.