Coupling ecological and geophysical processes three projects:Hydrology & riparian tree populations, Process model of fire frequency,Complex modular network of plant distribution.

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This research program has three projects connecting ecological and geoscience processes. 1. Most riparian tree studies are for sand-silt alluvial rivers. Here we will study the population dynamics of alder on a gravel bed-bedrock river and how the populations are influenced by the hydro-geomorphic processes. A hydraulic model will be used to determine where and how seeds become stranded on shore. After stranding, these stranding locations' temperature and water potential will be used in a hydro-thermal model of seed germination to predict times of seed germination. Finally, a water budget model will determine how the plant's growth rate maintains a positive water budget, and a mechanistic model will show how plants resist (or not) the river forces causing breakage and uprooting. The model in this project will give an integrated approach to the basic causal forces acting on most riparian trees and will thus help in riparian planning. 2. Determination of landscape fire frequency has been largely statistical curve fitting. This project will start the development of a causal-based simulation with integrated: climate/ meteorological model of fuel moisture and lightning ignition, a computational fluid dynamics (CFD) model of fire spread through thermally-thin vegetative fuels, a heat transfer and combustion model of how trees are killed, and then a tree population dynamics model after and between fires. This will start the development of a fire frequency based on governing equations. 3. Vegetation is critically controlled by moisture and its distribution on a landscape. This project defines the network patterns of saturated flow (topographic wetness values) on both real landscapes and landscapes created by landscape development models in geomorphology. This approach allows an understanding of how landscape structure and the hydrological, biotic, and geomorphic processes that create landscapes explain the moisture (and nutrient) gradients that so influence vegetation distribution. The application of this understanding could provide a process basis for biophysical land classification and ecosystem landscape processes.