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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #320084
Title: Functional approach to simulating short-rotation woody crops in process-based models

Author
item GUO, TIAN - Purdue University
item ENGEL, BERNARD - Purdue University
item SHAO, GANG - Purdue University
item Arnold, Jeffrey
item SRINIVASAN, RAGHAVAN - Texas A&M University
item Kiniry, James

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/21/2015
Publication Date: 11/9/2015
Publication URL: http://handle.nal.usda.gov/10113/62888
Citation: Guo, T., Engel, B.A., Shao, G., Arnold, J.G., Srinivasan, R., Kiniry, J.R. 2015. Functional approach to simulating short-rotation woody crops in process-based models. BioEnergy Research. 8:1598-1613.

Interpretive Summary: Energy security and sustainability require a suite of biomass crops, including woody species. Hybrid poplar and cottonwood (both hereafter referred to as Poplar) can produce large quantities of biofuel. Quantifying water use for Poplar growth is important should it be widely planted. Poplar growth and its impacts on runoff, sediment and nitrate losses were simulated by the Soil and Water Assessment Tool (SWAT). SWAT tree growth algorithms and parameters for hybrid poplar in Midwestern US and cottonwood in Southern US were improved based on hybrid poplar and cottonwood site data. Tree growth representation led to code changes including a new leaf area parameter, new leaf area index algorithm, and leaf biomass algorithm, while fraction of tree biomass accumulated each year converted to residue during dormancy was removed. The modified SWAT realistically simulated hybrid poplar leaf area index and aboveground woody biomass. The model reasonably simulated cottonwood aboveground biomass, seasonal runoff, sediment, nitrate-N, and total nitrate. Thus, the modified SWAT model can be used for modeling Poplar biofeedstock production and hydrologic and water quality response to its growth.

Technical Abstract: Energy security and sustainability require a suite of biomass crops, including woody species. Populus has the potential to produce significant quantities of biofuel. Quantifying hydrologic and water quality responses to Populus growth is important should it be widely planted. Populus growth and its impacts on runoff, sediment and nitrate-N losses were simulated by the Soil and Water Assessment Tool (SWAT). SWAT tree growth algorithms and parameters for hybrid poplar (Populus balsamifera L. × P.tristis Fisch) in Midwestern U.S. and cottonwood (Populus deltoides Bartr.) in Southern U.S. were improved based on hybrid poplar and cottonwood site data. Tree growth representation led to SWAT2012 code changes including a new leaf area parameter (TREED), new leaf area index algorithm, and leaf biomass algorithm, while fraction of tree biomass accumulated each year converted to residue during dormancy (BIO_LEAF) was removed. The modified SWAT simulated LAI, biomass yield, runoff, sediment and nitrate-N losses of Populus growth were compared with observed values. Performance of the modified SWAT simulated hybrid poplar LAI and aboveground woody biomass (PBIAS: -57 ~ 7%, NSE: 0.94 ~ 0.99, and R2: 0.74 ~ 0.99), and cottonwood aboveground biomass, seasonal mean runoff, mean sediment, mean nitrate-N and total nitrate-N were satisfactory (PBIAS: -39 ~ 11%, NSE: 0.86 ~ 0.99, and R2: 0.93 ~ 0.99). Improved algorithms and associated parameters, and values and potential parameter ranges for Populus were reasonable. Thus, the modified SWAT model can be used for Populus biofeedstock production modeling and hydrologic and water quality response to its growth.