A STELLA Model to Estimate Water and Nitrogen Dynamics in a Short-Rotation Woody Crop Plantation

Abstract

Although short-rotation woody crop biomass production technology has demonstrated a promising potential to supply feedstocks for bioenergy production, the water and nutrient processes in the woody crop planation ecosystem are poorly understood. In this study, a computer model was developed to estimate the dynamics of water and nitrogen (N) species (e.g., NH-N, NO-N, particulate organic N, and soluble organic N [SON]) in a woody crop plantation using STELLA (tructural hinking and xperiential earning aboratory with nimation) software. A scenario was performed to estimate diurnal and monthly water and N variations of a 1-ha mature cottonwood plantation over a 1-yr simulation period. A typical monthly variation pattern was found for soil water evaporation, leaf water transpiration, and root water uptake, with an increase from winter to summer and a decrease from summer to the following winter. Simulations further revealed that the rate of soil water evaporation was one order of magnitude lower than that of leaf water transpiration. In most cases, the relative monthly water loss rates could be expressed as evapotranspiration > root uptake > percolation > runoff. Leaching of NO-N and SON depended not only on soil N content but also on rainfall rate and duration. Leaching of NO-N from the cottonwood plantation was about two times higher than that of SON. The relative monthly rate of N leaching was NO-N > SON > NH-N. This study suggests that the STELLA model developed is a useful tool for estimating water and N dynamics from a woody crop plantation.

A STELLA-Based Model to Simultaneously Predict Hydrological Processes, N Uptake and Biomass Production in a Eucalyptus Plantation

“…A conceptual diagram showing the dynamics of water and N in a growing eucalyptus plantation is shown in Figure 1, which is modified from Ouyang et al [27]. Since the mathematical functions for soil water dynamics in a eucalyptus plantation have been published in Ouyang et al [28] and the mathematical functions for N dynamics are very similar to those in other short-rotation woody crop plantations that have been published by Ouyang et al [27], an elaborate description of these functions is beyond the scope of this study. However, the mechanisms for eucalyptus N uptake and biomass production in a growing plantation are not included in Ouyang et al [27,28].…”

“…For typical weather conditions, transpiration ceases at night due to stomata closure and resumes at dawn [29]. The diurnal factor in Equation ( 2) is introduced to reflect this daily variation and is given as [27]:…”

“…In summary, although the aforementioned experimental and modeling studies have provided valuable insights, little effort has been devoted to modeling eucalyptus biomass production as affected by water and N availability in conjunction with time series hydrological processes. Recently, Ouyang et al [27] developed a STELLA (Structural Thinking and Experiential Learning Laboratory with Animation) model to estimate water use and N uptake in a mature cottonwood plantation using an hourly time step. The model consists of water dynamics including surface runoff, rainfall/irrigation, evaporation, percolation, and water uptake by roots in the transpiration stream, as well as N dynamics including mineralization, nitrification, denitrification, sorption, leaching, volatilization, uptake, and fertilizer application.…”

“…The purpose of this study is to modify the cottonwood model developed by Ouyang et al [27] for simultaneously estimating soil hydrological processes, nitrogen (N) uptake, and biomass production in a eucalyptus (E. grandis × urophylla) plantation. More specifically, our objectives were to: (1) modify the STELLA model [27] to incorporate the eucalyptus biomass production component and its response to water use, N uptake, and stand age; (2) calibrate and validate the model using experimental data; and (3) apply the model to assess eucalyptus annual net primary production (ANPP) and woody biomass production (WBP), as well as their relationships to water use and N uptake during the entire cultivation period.…”

SIMULASI MODEL DINAMIK PENGARUH LEGUME COVER CROPS (LCC) TERHADAP LIMPASAN DAN SEDIMEN DI LAHAN HUTAN TANAMAN (Dynamic model simulation of the effects of Legume Cover Crops (LCC) on runoff and sediment in plantation forest land)

“…Siklus air dan hara pada ekosistem hutan dapat dipelajari dengan menggunakan model dinamik berbasis sistem (Ouyang, Zhang, Leininger, & Frey, 2015). Pada penelitian ini digunakan pendekatan model dinamik STELLA untuk melakukan simulasi skenario pengelolaan lingkungan pertumbuhan tanaman dalam mempengaruhi siklus air dan hara yang terjadi pada ekosistem.…”