Influences of Root Hydraulic Redistribution on N<sub>2</sub>O Emissions at AmeriFlux Sites

Fu, Congsheng; Lee, Xuhui; Griffis, Timothy J.; Wang, Guiling; Wei, Zhongwang

doi:10.1029/2018gl077789

Cited by 14 publications

(9 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Compared to SMS configuration, the water transported by plant root from deep to shallow soil layers (i.e., upward HR) in PHS supported plant survival and growth during drought events, which increased leaf stomatal conductance (Figure S4) and plant transpiration (Figure S5), and simultaneously promoted carbon uptake via photosynthesis and GPP. In contrast, downward HR that usually occurred during rainfall events transported water from shallow to deep soil layers, which might cause decrease of GPP, although downward HR could also help plant to survive during the following dry events/season (Fu, Lee, et al, 2018; Scott et al, 2008; Wu et al, 2020). The positive correlation between the PHS‐induced GPP increase and annual precipitation amount in the DRY region (Figure 10d) was caused by the fact that more water was available for upward HR when the limited annual precipitation increased from ~100 to ~200 mm yr −1 .…”

Section: Discussionmentioning

confidence: 99%

“…However, as we noted in the methods section, nighttime stomatal conductance tends toward zero in CLM5 simulation. The model deficiency in reproducing nighttime stomatal conductance and transpiration could lead to bias in simulations of HR and subsequently ecosystem GPP (Figures 11 and 13; Fu, Lee, et al, 2018; Wu et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

“…PHS allows for hydraulic redistribution (HR) and compensatory RWU, which means that roots can use a large portion of the soil column to buffer shortfalls in precipitation. Previous studies have incorporated various HR schemes into CLM4.5 and reported significant effects of HR on ecosystem carbon flux during dry seasons and dry events in wet seasons at the local scale (Fu et al, 2016; Fu, Lee, et al, 2018; Fu, Wang, et al, 2018; Wu et al, 2020). Reflecting HR in PHS is an important new feature of CLM5 (Kennedy et al, 2019), but the effects of HR on ecosystem carbon fluxes in different climate zones and during years with different precipitation features (e.g., an extreme dry year, a rainy year, a year with moderate annual precipitation but including serious dry events) remain unclear.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Plant Hydraulic Stress Strategy Improves Model Predictions of the Response of Gross Primary Productivity to Drought Across China

et al. 2020

JGR Atmospheres

Self Cite

View full text Add to dashboard Cite

The response of the terrestrial carbon cycle to droughts, which have recently increased in incidence and severity, is a hot topic in research, but the role played by vegetation water use strategies remains unclear. Both the soil moisture stress (SMS) and plant hydraulic stress (PHS) strategies are used in land surface models, but their performance in simulating the terrestrial carbon cycle and its response to droughts in various climatic zones remains uncertain. In this study, we used Community Land Model Version 5 to simulate gross primary productivity (GPP) across four different climatic subregions of China during 2000-2015 to investigate the roles played by PHS and SMS in the response of GPP to dry events and dry or rainy years in various climate zones. Simulated GPP with the two strategies were overestimated by 2.0-2.3% for the entire China compared to Moderate Resolution Imaging Spectroradiometer (MODIS) data. GPP simulated using PHS configuration fit eddy covariance and MODIS data better than that obtained using SMS across China, except for the Qinghai-Tibet Plateau. PHS increased simulated GPP by 0.10-0.63 g C m −2 day −1 during dry events across different climatic regions because of root hydraulic lift but decreased GPP by 0.37-0.45 g C m −2 day −1 during growing season in the humid southeastern region because of high atmospheric vapor pressure deficit and root hydraulic descent. Simulations forced by data collected locally in China performed better than those forced by CRUNCEP7 global data at the site but worse at the regional scale, in particular for the Qinghai-Tibet Plateau.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Plant Hydraulic Stress Strategy Improves Model Predictions of the Response of Gross Primary Productivity to Drought Across China

et al. 2020

JGR Atmospheres

Self Cite

View full text Add to dashboard Cite

show abstract

“…When HR strongly modulates N mineralization, immobilization, and plant N uptake in the dry season, soil nitrogen decomposition and soil nitrate concentration will be significantly decreased. N 2 O emission is thus reduced [35]. Moreover, HR affects the land-atmosphere water exchange and further feedbacks on the climate.…”

Section: Hydraulic Redistribution (Hr) Implementation and The Implicationmentioning

confidence: 99%

New Representation of Plant Hydraulics Improves the Estimates of Transpiration in Land Surface Model

Wei

et al. 2021

Forests

Self Cite

View full text Add to dashboard Cite

Transpiration represents more than 30% of the global land–atmosphere water exchange but is highly uncertain. Plant hydraulics was ignored in traditional land surface modeling, but recently plant hydraulics has been found to play an essential role in transpiration simulation. A new physical-based representation of plant hydraulic schemes (PHS) was recently developed and implemented in the Common Land Model (CoLM). However, it is unclear to what extent PHS can reduce these uncertainties. Here, we evaluated the PHS against measurements obtained at 81 FLUXNET sites. The transpiration of each site was estimated using an empirical evapotranspiration partitioning approach. The metric scores defined by the International Land Model Benchmarking Project (ILAMB) were used to evaluate the model performance and compare it with that of the CoLM default scheme (soil moisture stress (SMS)). The bias score of transpiration in PHS was higher than SMS for most sites, and more significant improvements were found in semi-arid and arid sites where transpiration was limited by soil moisture. The hydraulic redistribution in PHS optimized the soil water supply and thus improved the transpiration estimates. In humid sites, no significant improvement in seasonal or interannual variability of transpiration was simulated by PHS, which can be explained by the insensitivity of transpiration demand coupled to the photosynthesis response to precipitation. In arid and semi-arid sites, seasonal or interannual variability of transpiration was better captured by PHS than SMS, which was interpreted by the improved drought sensitivity for transpiration. Arid land is widespread and is expected to expand due to climate change, thus there is an urgent need to couple PHS in land surface models.

show abstract

“…Soil water dynamics reflect the comprehensive influences of rainfall, evapotranspiration, and lateral leaching; therefore, we used the soil water content to validate the modeling results for the water cycle. In our previous C/N modeling studies based on CLM4.5, CLM4.5 roughly captured the net ecosystem exchange (NEE) dynamics at a site in Minnesota representing the United States Corn Belt, a Douglas fir site in Washington State, a Mesquite Savanna site in Arizona, an oak pine forest site in southern California, and an Amazon evergreen forest site in Brazil [30,31]. Moreover, CLM4.5 reproduced gross primary production (GPP), net primary production (NPP), soil organic C content, and litter and fine root masses [31].…”

Section: Land Surface Modelmentioning

confidence: 99%

Influences of Extreme Weather Conditions on the Carbon Cycles of Bamboo and Tea Ecosystems

Zhu

Gao

et al. 2018

Forests

Self Cite

View full text Add to dashboard Cite

Tea plantations have expanded rapidly during the past several decades in China, the top tea-producing country, as a result of economic development; however, few studies have investigated the influence of tea plantations on the carbon cycle, especially from the perspective of climate change and increases in extreme weather events. Therefore, we employed combined observational and modeling methods to evaluate the water and carbon cycles at representative bamboo and tea plots in eastern China. Green tea growth and the corresponding water and carbon cycles were reproduced using the Community Land Model after applying fertilizer. Old-growth bamboo was reasonably simulated as broadleaf evergreen forest in this model. The mean observed soil respiration ranged from 1.79 to 2.57 and 1.34 to 1.50 µmol m−2 s−1 at the bamboo and tea sites, respectively, from April 2016 to October 2017. The observed soil respiration decreased by 23% and 55% due to extreme dryness in August 2016 at the bamboo and tea plots, respectively, and the model reproduced these decreases well. The modeling results indicated that tea acted as a stronger carbon sink during spring and a stronger carbon source during autumn and winter compared with old-growth bamboo. The carbon cycle was affected more by extremely dry weather than by extremely wet weather in both the bamboo and tea plots. Extremely dry periods markedly reduced the carbon sink at both plots, although this trend was more pronounced at the tea plot.

show abstract

Influences of Root Hydraulic Redistribution on N₂O Emissions at AmeriFlux Sites

Cited by 14 publications

References 50 publications

Plant Hydraulic Stress Strategy Improves Model Predictions of the Response of Gross Primary Productivity to Drought Across China

Plant Hydraulic Stress Strategy Improves Model Predictions of the Response of Gross Primary Productivity to Drought Across China

New Representation of Plant Hydraulics Improves the Estimates of Transpiration in Land Surface Model

Influences of Extreme Weather Conditions on the Carbon Cycles of Bamboo and Tea Ecosystems

Contact Info

Product

Resources

About

Influences of Root Hydraulic Redistribution on N2O Emissions at AmeriFlux Sites

Cited by 14 publications

References 50 publications

Plant Hydraulic Stress Strategy Improves Model Predictions of the Response of Gross Primary Productivity to Drought Across China

Plant Hydraulic Stress Strategy Improves Model Predictions of the Response of Gross Primary Productivity to Drought Across China

New Representation of Plant Hydraulics Improves the Estimates of Transpiration in Land Surface Model

Influences of Extreme Weather Conditions on the Carbon Cycles of Bamboo and Tea Ecosystems

Contact Info

Product

Resources

About

Influences of Root Hydraulic Redistribution on N₂O Emissions at AmeriFlux Sites