Introduction
Annually, Idaho’s forests extract thousands of tons of water from each hectare of soil while producing tons of carbon-based biomass: carbon/water fluxes are fundamentally linked. Recent reports by the National Academy of Sciences emphasize the need to better understand the sources and sinks of carbon dioxide and other greenhouse gases and the impacts of human and natural processes on these sources/sinks. The North American Carbon Plan emphasizes the need for both measurements and modeling of carbon storage and fluxes over various ecosystems and the integration of measurements and mechanistic models at multiple scales.

Idaho’s EPSCoR investment will provide measurements and modeling of coupled carbon/water fluxes in forest-landscape-climate types not currently represented in existing nation-wide efforts (i.e., mixed-age, mixed-conifer forest ecosystems in moderate-elevation, complex terrain, with a sustained dry period during the growing season). This work will include isotopic tests of the processes simulated by the models, thus strengthening our understanding of the coupling between the carbon and water balance and our ability to quantify the impact of large-scale disturbances (i.e., insects/disease, species replacement, climate change) on carbon/water fluxes. Idaho is well-suited for these studies because water availability is a limiting factor in plant growth, making the coupling of carbon/water flux particularly important, and much of the available water comes from snowpack at moderate elevations, which is particularly vulnerable to climate changes.

Research Plan
The research goal is to understand and quantify the magnitude, timing, distribution, and coupling of carbon and water fluxes in mountainous forestlands. Key processes include the exchange of carbon/water between the atmosphere and the land surface (i.e., soil and vegetation) and the flux and storage of carbon/water by the soil and vegetation. These will be addressed via three key objectives: 1) to improve the biophysics of the models at the tree and canopy scale by merging innovative measurements with models; 2) to evaluate the impacts of human and natural perturbations on regional carbon balance by applying models at the landscape scale; and 3) to simulate the impacts of climate change and/or policy decisions by using models in a predictive mode. Research efforts are framed around three specific questions:

1. How do carbon and water fluxes from individual trees and soils contribute to aggregated canopy-scale fluxes (~100 m2) and vary seasonally and spatially?

2. How do canopy-scale fluxes and their coupling vary with disturbance, specifically species replacement, insect infestation, and climate variability?

3. How much improvement in existing canopy and landscape-scale models can be achieved by enhanced coupling of carbon and water dynamics? Which parameters can be estimated using remote sensing, and how accurately can parameters be measured?

Mica Creek Experimental Watershed Website