Water- and Plant-Mediated Responses of Ecosystem Carbon Fluxes to Warming and Nitrogen Addition on the Songnen Grassland in Northeast China

Jiang, Li; Guo, Rui; Zhu, Tingcheng; Niu, Xuedun; Guo, Jixun; Sun, Wei

doi:10.1371/journal.pone.0045205

Cited by 38 publications

(40 citation statements)

References 36 publications

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“…Experimental warming also reduced average GPP and AGB in 2012 in the alpine meadow at the low elevation [52] and it was also a drier year of 2012 (312.8 mm) compared to the mean precipitation of 1963–2015 (Fig 1). These implied that the response directions of plant growth to experimental warming varied with years and experimental warming did not have a continuous negative effect on biomass production at the low elevation, which was in line with previous studies [27–29,53,54]. The variable response directions may be due to the variable environmental temperature and humidity among years [27,29] and plant growth was more sensitive to moisture than temperature change when water was lower than a certain threshold value [53,55].…”

Section: Resultssupporting

confidence: 91%

“…These implied that the response directions of plant growth to experimental warming varied with years and experimental warming did not have a continuous negative effect on biomass production at the low elevation, which was in line with previous studies [27–29,53,54]. The variable response directions may be due to the variable environmental temperature and humidity among years [27,29] and plant growth was more sensitive to moisture than temperature change when water was lower than a certain threshold value [53,55]. The precipitation in 2014 was 38.6 mm higher compared to the mean precipitation (398.7 mm), whereas the precipitation in 2012 and 2015 was 85.88 mm and 98.48 mm lower compared to the mean precipitation, respectively.…”

Section: Resultssupporting

confidence: 91%

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Environmental Humidity Regulates Effects of Experimental Warming on Vegetation Index and Biomass Production in an Alpine Meadow of the Northern Tibet

Shen

2016

PLoS ONE

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Uncertainty about responses of vegetation index, aboveground biomass (AGB) and gross primary production (GPP) limits our ability to predict how climatic warming will influence plant growth in alpine regions. A field warming experiment was conducted in an alpine meadow at a low (4313 m), mid- (4513 m) and high elevation (4693 m) in the Northern Tibet since May 2010. Growing season vapor pressure deficit (VPD), soil temperature (Ts) and air temperature (Ta) decreased with increasing elevation, while growing season precipitation, soil moisture (SM), normalized difference vegetation index (NDVI), soil adjusted vegetation index (SAVI), AGB and GPP increased with increasing elevation. The growing season Ta, Ts and VPD in 2015 was greater than that in 2014, while the growing season precipitation, SM, NDVI, SAVI, AGB and GPP in 2015 was lower than that in 2014, respectively. Compared to the mean air temperature and precipitation during the growing season in 1963–2015, it was a warmer and wetter year in 2014 and a warmer and drier year in 2015. Experimental warming increased growing season Ts, Ta,VPD, but decreased growing season SM in 2014–2015 at all the three elevations. Experimental warming only reduced growing season NDVI, SAVI, AGB and GPP at the low elevation in 2015. Growing season NDVI, SAVI, AGB and GPP increased with increasing SM and precipitation, but decreased with increasing VPD, indicating vegetation index and biomass production increased with environmental humidity. The VPD explained more variation of growing season NDVI, SAVI, AGB and GPP compared to Ts, Ta and SM at all the three elevations. Therefore, environmental humidity regulated the effect of experimental warming on vegetation index and biomass production in alpine meadows on the Tibetan Plateau.

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 91%

Environmental Humidity Regulates Effects of Experimental Warming on Vegetation Index and Biomass Production in an Alpine Meadow of the Northern Tibet

Shen

2016

PLoS ONE

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“…In general, ecosystem C fluxes are closely related to SWC in grassland ecosystem [28], [29]. However, we found no significant relationship between ecosystem C fluxes and SWC in our freshwater wetland.…”

Section: Discussionmentioning

confidence: 60%

Effects of Elevated CO2 and Nitrogen Deposition on Ecosystem Carbon Fluxes on the Sanjiang Plain Wetland in Northeast China

Wang

Zhu

et al. 2013

PLoS ONE

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BackgroundIncreasing atmospheric CO2 and nitrogen (N) deposition across the globe may affect ecosystem CO2 exchanges and ecosystem carbon cycles. Additionally, it remains unknown how increased N deposition and N addition will alter the effects of elevated CO2 on wetland ecosystem carbon fluxes.Methodology/Principal FindingsBeginning in 2010, a paired, nested manipulative experimental design was used in a temperate wetland of northeastern China. The primary factor was elevated CO2, accomplished using Open Top Chambers, and N supplied as NH4NO3 was the secondary factor. Gross primary productivity (GPP) was higher than ecosystem respiration (ER), leading to net carbon uptake (measured by net ecosystem CO2 exchange, or NEE) in all four treatments over the growing season. However, their magnitude had interannual variations, which coincided with air temperature in the early growing season, with the soil temperature and with the vegetation cover. Elevated CO2 significantly enhanced GPP and ER but overall reduced NEE because the stimulation caused by the elevated CO2 had a greater impact on ER than on GPP. The addition of N stimulated ecosystem C fluxes in both years and ameliorated the negative impact of elevated CO2 on NEE.Conclusion/SignificanceIn this ecosystem, future elevated CO2 may favor carbon sequestration when coupled with increasing nitrogen deposition.

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“…In addition to GPP, ecosystem respiration is also sensitive to warming and changes in phenology [37,52]. Warmer air and soil temperatures will have direct effects on plant autotrophic and soil heterotrophic respiration.…”

Section: Discussionmentioning

confidence: 99%

Variability and Changes in Climate, Phenology, and Gross Primary Production of an Alpine Wetland Ecosystem

et al. 2016

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Abstract:Quantifying the variability and changes in phenology and gross primary production (GPP) of alpine wetlands in the Qinghai-Tibetan Plateau under climate change is essential for assessing carbon (C) balance dynamics at regional and global scales. In this study, in situ eddy covariance (EC) flux tower observations and remote sensing data were integrated with a modified, satellite-based vegetation photosynthesis model (VPM) to investigate the variability in climate change, phenology, and GPP of an alpine wetland ecosystem, located in Zoige, southwestern China. Two-year EC data and remote sensing vegetation indices showed that warmer temperatures corresponded to an earlier start date of the growing season, increased GPP, and ecosystem respiration, and hence increased the C sink strength of the alpine wetlands. Twelve-year long-term simulations (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011) showed that: (1) there were significantly increasing trends for the mean annual enhanced vegetation index (EVI), land surface water index (LSWI), and growing season GPP (R 2 ě 0.59, p < 0.01) at rates of 0.002, 0.11 year´1 and 16.32 g¨C¨m´2¨year´1, respectively, which was in line with the observed warming trend (R 2 = 0.54, p = 0.006); (2) the start and end of the vegetation growing season (SOS and EOS) experienced a continuous advancing trend at a rate of 1.61 days¨year´1 and a delaying trend at a rate of 1.57 days¨year´1 from 2000 to 2011 (p ď 0.04), respectively; and (3) with increasing temperature, the advanced SOS and delayed EOS prolonged the wetland's phenological and photosynthetically active period and, thereby, increased wetland productivity by about 3.7-4.2 g¨C¨m´2¨year´1 per day. Furthermore, our results indicated that warming and the extension of the growing season had positive effects on carbon uptake in this alpine wetland ecosystem.

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Water- and Plant-Mediated Responses of Ecosystem Carbon Fluxes to Warming and Nitrogen Addition on the Songnen Grassland in Northeast China

Cited by 38 publications

References 36 publications

Environmental Humidity Regulates Effects of Experimental Warming on Vegetation Index and Biomass Production in an Alpine Meadow of the Northern Tibet

Environmental Humidity Regulates Effects of Experimental Warming on Vegetation Index and Biomass Production in an Alpine Meadow of the Northern Tibet

Effects of Elevated CO2 and Nitrogen Deposition on Ecosystem Carbon Fluxes on the Sanjiang Plain Wetland in Northeast China

Variability and Changes in Climate, Phenology, and Gross Primary Production of an Alpine Wetland Ecosystem

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