Regolith-tree-atmosphere water transport on bedrock, rock joints, and talus and wildfire-mesoscale coupled models

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This research program's goal is to enhance understanding of ecosystem processes by focusing on the integrative connections between ecological processes and the geosphere, hydrosphere, and atmosphere processes. ***Our first set of projects is to model the processes that connect wildfire, fuel, and weather dynamics to the ecological effects of the wildfire at the individual plant and population levels. The project proposes coupling (interacting) a wildfire process model to a mesoscale weather model. The significant advance is the beginnings of a complete fire behaviour-fire ecology- atmospheric model that can be tested in operational situations. This model can be used for hindcasting and forecasting of wildfires (Bakhshaii & Johnson 2017). We have already incorporated as a subprogram in the wildfire model the ecological effect of necrosis and mortality of trees (Michaletz & Johnson 2006; 2008; 2012). The innovation is the coupling of weather at multiple scales and in the use of assimilation methods to improve accuracy of wildfire behaviour (flame length, smoke distribution, rate of spread and pattern of spread) in boreal and subalpine forests. The model proposed here is a coupled system between the combustion and atmospheric processes. This is an important change in viewpoint from the current correlations of fire heat output and rate of spread with temperature, relative humidity. precipitation and wind to a coupled combustion and fluid dynamics process model, in other words showing how the fire works and is influenced by its interaction with mesoscale weather. ***Our second set of projects is to explain how trees survive on three extreme but abundant habitats in the Canadian Rockies that are rarely studied and make up more then half of the area. The significance is that these projects combine geomorphic, hydrologic, and ecologic processes and that these abundant mountain habitats play an important role in the water budgets of these mountain water towers. The approach is to model the water budgets as a soil-root-stem-leaf-atmosphere continuum of water flow to understand their regulation. In addition, the use of stable isotopes will allow determination of the length of time it takes for water from various sources (precipitation, in rocks, in joints, in talus or different rock types) to be transpired by trees. The factors affecting trees on each habitat are different. The cliff habitat has stress joints and bedding planes that have little soil and limited water supply and hence high-water stress. Talus (scree) have talus movement and a surface layer of larger rocks and the subsurface layer of smaller sediment (i.e. well drained surface and moister subsurface). Consequently, the trees have to deal with the competing processes of uprooting and water stress. The third habitat of bedrock hillslopes has varied bedrock types and slope angles and thus varied soil depth and water supply over very short distances. **