Our research group works at the interface between global change biology, macroecology/biogeography, community and ecosystem ecology.  Much of our research focuses on understanding the biological and climatic drivers that promote shrub expansion and the ecosystem consequences of this vegetation change for tundra ecosystem functions.

We are currently funded by the NERC ShrubTundra project (NE/M016323/1) that sets out to quantify the role of climate as a driver of tundra shrub expansion and tundra greening.

Research Questions

1. How is tundra vegetation changing in response to global change?

There is growing evidence for increasing shrubs in many tundra ecosystems. Increased shrubs could be due to a warming climate and improved growing conditions or a variety of other factors. We use historical data sets such as repeat photography to explore vegetation change in tundra ecosystems. We are interested in research questions such as whether shrub species have the potential to form dominant canopies at the northern range edge or whether growth forms are locally adapted.

2. Does on-the-ground vegetation change correspond with satellite observations of tundra greening?

Satellites are observing a greening of tundra ecosystems concurrent with the recent Arctic warming trend.  Does this greening correspond with on-the-ground observations of vegetation change?  We work with circumArctic datasets and collaborators at sites around the Arctic (ShrubHub, sTUNDRA, ITEX), remotely sensed satellite data and drones (remotely piloted aircraft systems or UAVs) to ask this scaling question at our focal research sites and across the tundra biome as a whole.

3. How will vegetation change modify the tundra ecosystem function?

We investigate the feedbacks among vegetation change, ecosystem functions and climate. Shrubs can influence the reflectivity (albedo) of tundra ecosystems which could feedback to influence climate warming. In winter, shrubs can trap snow.  In summer, shrubs can shade soils. Changes in plant litter inputs can influence the rates of decomposition of tundra soils. These processes could feedback to influence nutrient cycling, carbon stores and biodiversity.  We work with trait databases (TRY), field experiments (Tundra Tea Bag Experiment) and hierarchical models to test the relationships between vegetation change, warming, trait change and ecosystem functions.

Research Approaches

Much of our field research takes place in the Yukon Territory of Northern Canada. In the Kluane Region of the Southwest Yukon, we are exploring changes in the shrubline ecotone. At the Qiqiktaruk – Herschel Island site on the Arctic Coast of the Yukon Territory, we are exploring vegetation-permafrost interactions.

Much of our research is field-based experimental or observational ecology. We conduct collaborative research, use large scale data sets and statistical modelling to explore patterns of change at the tundra biome scale. We use dendroecology to work back in time and understand how shrub growth has changed over the previous decades and to estimate the climate sensitivity of shrub growth. We have established a common garden experiment in 2013 to test for local adaptation in growth form in tundra willows across climate and latitudinal gradients. And we have recently begun to work with drones (remotely piloted aircraft systems or UAVs) to link on-the-ground measurements and satellite observations of tundra vegetation change.