Catchment-Scale Modeling of Nitrogen Dynamics in a Temperate Forested Watershed, Oregon. An Interdisciplinary Communication Strategy

Kellie Vaché,Julia Jones,Lutz Breuer,Phil Sollins

doi:10.3390/w7105345

Kellie Vaché, Julia Jones + Show 2 more

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https://doi.org/10.3390/w7105345

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Journal: Water	Publication Date: Oct 12, 2015
Citations: 46	License type: CC BY 4.0

Affiliation: Oregon State University, University of Giessen

Abstract

We present a systems modeling approach to the development of a place-based ecohydrological model. The conceptual model is calibrated to a variety of existing observations, taken in watershed 10 (WS10) at the HJ Andrews Experimental Forest (HJA) in Oregon, USA, a long term ecological research (LTER) site with a long history of catchment-scale data collection. The modeling framework was designed to help document and evaluate an evolving understanding of catchment processing of water, nitrogen, and carbon that has developed over the many years of on-going research at the site. We use the dynamic model to capture the temporal variation in the N and C budgets and to evaluate how different components of the complex system may control the retention and release of N in this pristine forested landscape. Results indicate that the relative roles of multiple competing controls on N change seasonally, between periods of wet/dry and growth/senescence. The model represents a communication strategy to facilitate dialog between disciplinary experimentalists and modelers, to produce a more complete picture of nitrogen cycling in the region. We view this explicit development of complete, yet conceptually simplified models as a useful and important way to evaluate complex environmental dynamics.

Highlights

Human-induced changes to global biogeochemical cycles are large, having for example effectively doubled the global rate of annual N fixation [1] yet the ultimate response of ecosystems to these changes remains unclear
The detailed study of each of these individual units tends to be well-covered by traditional disciplines, such as hillslope hydrology, aquatic ecology, soil biogeochemistry, forest ecology, etc., but with less attention given to the relationships between components
A wide variety of models have been developed to evaluate questions related to nitrogen dynamics, with the variation primarily manifested as different levels of complexity, different scales of application, and different questions of interest

Summary

Introduction

Human-induced changes to global biogeochemical cycles are large, having for example effectively doubled the global rate of annual N fixation [1] yet the ultimate response of ecosystems to these changes remains unclear This lack of clarity is due in part to the inter-dependencies and feedbacks between system components as well as to an incomplete understanding of the complex processes governing biogeochemical cycles. The detailed study of each of these individual units tends to be well-covered by traditional disciplines, such as hillslope hydrology, aquatic ecology, soil biogeochemistry, forest ecology, etc., but with less attention given to the relationships between components That these dependencies, in some sense by definition, fall at interfaces between traditional disciplinary boundaries is an ongoing challenge for ecosystem science, though the emergence of cross-cutting disciplines, such as ecohydrology and hydrobiogeochemistry, is an indication that this challenge is being addressed. The use of numerical models, which are designed to capture relationships between system components, represents one method that can be used to contribute to our understanding of how ecosystems function, and how they may respond to future change in both climate and landcover

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