The effect of introducing a winter forage rotation on CO2 fluxes at a temperate grassland

Kiely, Gerard

doi:10.1016/j.agee.2012.05.001

Cited by 7 publications

(2 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Most EC systems have been deployed over natural vegetation, while grazed pastures have been studied less often. This imbalance is gradually receding as a number of studies of grazed pastures have been published more recently (e.g., Zeeman et al, 2010;Klumpp et al, 2011;Peichl et al, 2012;Leahy and Kiely, 2012;Wohlfahrt et al, 2012). However, there is still only limited experience with the study of grazed pastures that have to deal with the particular challenge of having small, but continuous, fluxes from GPP and plant and soil respiration that are occasionally punctuated by much larger fluxes from animal respiration during grazing events.…”

Section: Introductionmentioning

confidence: 97%

Modelling carbon and water exchange of a grazed pasture in New Zealand constrained by eddy covariance measurements

Kirschbaum

Rutledge

Kuijper

et al. 2015

Science of The Total Environment

View full text Add to dashboard Cite

We used two years of eddy covariance (EC) measurements collected over an intensively grazed dairy pasture to better understand the key drivers of changes in soil organic carbon stocks. Analysing grazing systems with EC measurements poses significant challenges as the respiration from grazing animals can result in large short-term CO2 fluxes. As paddocks are grazed only periodically, EC observations derive from a mosaic of paddocks with very different exchange rates. This violates the assumptions implicit in the use of EC methodology. To test whether these challenges could be overcome, and to develop a tool for wider scenario testing, we compared EC measurements with simulation runs with the detailed ecosystem model CenW 4.1. Simulations were run separately for 26 paddocks around the EC tower and coupled to a footprint analysis to estimate net fluxes at the EC tower. Overall, we obtained good agreement between modelled and measured fluxes, especially for the comparison of evapotranspiration rates, with model efficiency of 0.96 for weekly averaged values of the validation data. For net ecosystem productivity (NEP) comparisons, observations were omitted when cattle grazed the paddocks immediately around the tower. With those points omitted, model efficiencies for weekly averaged values of the validation data were 0.78, 0.67 and 0.54 for daytime, night-time and 24-hour NEP, respectively. While not included for model parameterisation, simulated gross primary production also agreed closely with values inferred from eddy covariance measurements (model efficiency of 0.84 for weekly averages). The study confirmed that CenW simulations could adequately model carbon and water exchange in grazed pastures. It highlighted the critical role of animal respiration for net CO2 fluxes, and showed that EC studies of grazed pastures need to consider the best approach of accounting for this important flux to avoid unbalanced accounting.

show abstract

Section: Introductionmentioning

confidence: 97%

Modelling carbon and water exchange of a grazed pasture in New Zealand constrained by eddy covariance measurements

Kirschbaum

Rutledge

Kuijper

et al. 2015

Science of The Total Environment

View full text Add to dashboard Cite

show abstract

“…Numerous studies were conducted previously to explore how carbon fluxes and/or ecosystem productivity respond to different managerial factors or species composition within pasture ecosystems [6][7][8][9][10]. For example, Skinner [9] found that season alterations (winter vs. summer) can significantly impact ecosystem productivity and carbon balance of cool-season pasture ecosystems.…”

Section: Introductionmentioning

confidence: 99%

Assessing and Modeling Ecosystem Carbon Exchange and Water Vapor Flux of a Pasture Ecosystem in the Temperate Climate-Transition Zone

Chen

Nevins

et al. 2021

Agronomy

View full text Add to dashboard Cite

The rising frequency of extreme weather events and global warming are greatly challenging pastoral ecosystem productivity, particularly in the temperate climate-transition regions. While this could cause greater gross primary production (GPP) mainly contributed by the warm-season vegetation, the consequences for the dynamics of net ecosystem exchange (NEE) and hydrological responses (e.g., evapotranspiration, ET) on an ecosystem level are poorly known. Here, we investigated the evolution of plant phenology, nutritive value, energy balance, and carbon/water budgets of a cool-season dominated pastoral ecosystem in the temperate zone; integrating both eddy covariance (EC) flux measurement and simulation modeling-based uncertainty analysis. Throughout the two-year duration (2017–2018) of this study, the entire pasture ecosystem remained a strong carbon sink (NEE = −1.23 and −1.95 kg C m−2, respectively) with 74% and 62% of available energy loss explained by EC fluxes, respectively. The cumulative ET was 735.8 and 796.8 mm, respectively; and the overall ecosystem water use efficiency (EWUE) were calculated as 6.5 g C kg−1 water across both growing seasons. The above-ground biomass yield agreed with the cumulative GPP and was inversely correlated with grass nutritive value. The uncertainty analysis indicated that accurate EC flux gap-filling models could be constructed using support vector machine trained time-series models (NEE, R2 = 0.77, RMSE = 11.8; ET, R2 = 0.90, RMSE = 73.8). The performance benchmarking tests indicated that REddyProc-based gap-filling performance was very limiting and highly variable (NEE, R2 = 0.21–0.64; ET, R2 = 0.79–0.87), particularly for estimating NEE. Overall, the warm-season vegetation encroachment greatly filled the production gap of cool-season grasses, leading to greater cumulative NEE and EWUE on a system level, compared with those from many other reported field-crop or grassland studies using EC approaches. The complex and dynamic nature of grassland ecosystems greatly challenged the conventional REddyProc-based EC flux gap-filling performance. However, accurate machine learning models could be constructed for error/uncertainty control purposes and, thus, should be encouraged in future studies.

show abstract

Greenhouse-gas budgets for irrigated dairy pasture and a winter-forage kale crop

Laubach

Hunt

2018

Agricultural and Forest Meteorology

View full text Add to dashboard Cite

The effect of introducing a winter forage rotation on CO2 fluxes at a temperate grassland

Cited by 7 publications

References 35 publications

Modelling carbon and water exchange of a grazed pasture in New Zealand constrained by eddy covariance measurements

Modelling carbon and water exchange of a grazed pasture in New Zealand constrained by eddy covariance measurements

Assessing and Modeling Ecosystem Carbon Exchange and Water Vapor Flux of a Pasture Ecosystem in the Temperate Climate-Transition Zone

Greenhouse-gas budgets for irrigated dairy pasture and a winter-forage kale crop

Contact Info

Product

Resources

About