Redlins MONet Request
EMSL Project ID
60921
Abstract
Hydraulic redistribution (HR) is the passive movement of water within the soil profile via biological pathways (namely roots and fungal hyphae) from wetter areas to drier areas. The translocation of water from deep soil to the upper soil horizons may have important implications on root morphology, soil-biologic activity, solute transport, carbon stability dynamics, and soil physical and structural properties, especially in water-limited environments such as that found on the western slopes of the Oregon Cascade Mountains. This region is typical of a Mediterranean climate wherein nearly all of its precipitation falls as rain throughout the winter which is contrasted by an extended summer dry period when little to no precipitation occurs. We seek to elucidate how hydraulic redistribution may alter soil physical and biological properties, as well as nutrient dynamics, in what would otherwise be two very similar hillslopes. To explore this, we have chosen sites on two adjacent hillslopes within the HJ Andrews Experimental Forest which have been shown, through previous study, to experience two contrasting hydraulic redistribution regimes: high HR activity, and little to no HR activity. Watersheds within HJ Andrews are typical representations of low-elevation, mixed-use catchments found throughout the western Cascades of Oregon. The hillslopes selected within the Andrews Forest are defined less by differences in surface vegetation, land-use history, and underlying lithology, but are believed to be more defined by differences in water accessibility and near-surface hydrologic variability throughout the summer dry season. It is hypothesized that differences in the relative magnitude of HR, even within high- and low-HR plots, are a result of variation in groundwater accessibility to surface vegetation, and to trees in particular. As such, two sites on each hillslope, one on the toe-slope and one on the mid-slope (4 sites total), have been selected for this project to best capture both inter- and intra-plot variation in groundwater accessibility, and 3 sampling events have been chosen to highlight changes that occur at each site across an entire period of seasonal drought. The MONet soil program will allow us to analyze changes in soil physical properties, carbon dynamics, and biologic activity associated with the near surface soils that are most impacted by the influx of redistributed water. Core and sample collection for the MONet soil program will occur alongside existing efforts at each site to map the magnitude, location, geometry, and flow paths of near surface water using state-of-the-art geophysical techniques. Combined, the MONet soil program and existing research efforts at the sites will provide important insight into the dynamic soil processes associated with variable water accessibility under drought conditions. Furthermore, the national focus of the MONet soil program will allow for exploration into the scalability of our findings.
Project Details
Project type
MONet
Start Date
2023-05-05
End Date
N/A
Status
Active
Released Data Link
Team
Principal Investigator
Team Members