Forest structural controls on boreal peatland eco-hydrology

Boreal peatlands are globally important carbon stores, holding ~22% of terrestrial Carbon. The composition and structure of their vegetation controls the rates and direction of globally important mass and energy fluxes. However, the effect of system structure on functioning and disturbance response remains largely un-known. This PhD investigates how forested peatland structure and organisation influences key eco-hydrological processes at the peatland-atmosphere interface. The primary research outcomes are: (1) disturbance of forest-canopy layers changes the spatio-temporal dynamics of peatland surface temperatures which, vary substantially in space and time, (2) different system structural layers have varying controls on peat-surface temperatures, and their disturbance changes the thermal regime even when no change in mean temperature is observed, (3) meter-scale spatial variability in surface energy balance induced by the tree-canopy, substantially impacts simulated peatland evapotranspiration (ET), increasing ET by 25% and reducing unexplained variance between modelled and measured ET by 8%, (4) responses of key bryophytes to canopy removal is lagged in peatlands (unlike mineral soils), highlighting the potentially important influence of transition periods (system lags) on eco-hydrological feedbacks mechanisms to disturbance. This research provides important new understating of the eco-hydrological functioning of peatland-atmosphere interfaces. It characterises the dynamics of system variability (both intact and disturbed), evidences of how energy and mass flux estimates may be improved, and details how small scale-research could yield important information for assessing changes to system functioning.