scholarly journals Effects of nitrogen fertilization on the understorey carbon balance over the growing season in a boreal Pine forest

2013 ◽  
Vol 10 (8) ◽  
pp. 14093-14113
Author(s):  
D. B. Metcalfe ◽  
B. Eisele ◽  
N. J. Hasselquist
Keyword(s):  
Boreal Forests ◽  
Nitrogen Availability ◽  
Growing Season ◽  
Carbon Fluxes ◽  
Nitrogen Addition ◽  
Carbon Uptake ◽  
Sink Strength ◽  
Understorey Vegetation ◽  
Ecosystem Carbon ◽  
Photosynthetic Carbon

Abstract. Boreal forests play a key role in the global carbon cycle and are facing rapid shifts in nitrogen availability with poorly understood consequences for ecosystem function and global climate. We quantified the effects of nitrogen availability on carbon fluxes from a relatively understudied component of these forests – understorey vegetation – at three intervals over the summer growing period in a northern Swedish Scots Pine stand. Nitrogen addition altered both photosynthetic carbon uptake and respiratory release, but the magnitude and direction of this effect depended on the time during the growing season and the amount of nitrogen added. Specifically, nitrogen addition stimulated net ecosystem carbon uptake only in the late growing season. We find evidence for species-specific control of understorey carbon sink strength, as photosynthesis per unit ground area was positively correlated only with the abundance of the vascular plant Vaccinium myrtillus and no others. Comparison of photosynthetic carbon uptake with data on plant carbon dioxide release from the study site, indicate that understorey vegetation photosynthate was mainly supplying respiratory demands for much of the year. Only in the late season with nitrogen addition did understorey vegetation appear to experience a large surplus of carbon in excess of respiratory requirements. Further work, simultaneously comparing all major biomass and respiratory carbon fluxes in understorey and tree vegetation, is required to resolve the likely impacts of environmental changes on whole-ecosystem carbon sequestration in boreal forests.

scholarly journals Effects of nitrogen fertilization on the forest floor carbon balance over the growing season in a boreal pine forest

2013 ◽  
Vol 10 (12) ◽  
pp. 8223-8231 ◽  
Author(s):  
D. B. Metcalfe ◽  
B. Eisele ◽  
N. J. Hasselquist
Keyword(s):  
Boreal Forests ◽  
Forest Floor ◽  
Nitrogen Availability ◽  
Environmental Changes ◽  
Vascular Plant ◽  
Growing Season ◽  
Carbon Fluxes ◽  
Nitrogen Addition ◽  
Sink Strength ◽  
Understorey Vegetation

Abstract. Boreal forests play a key role in the global carbon cycle and are facing rapid shifts in nitrogen availability with poorly understood consequences for ecosystem function and global climate change. We quantified the effects of increasing nitrogen availability on carbon fluxes from a relatively understudied component of these forests – the forest floor – at three intervals over the summer growing period in a northern Swedish Scots pine stand. Nitrogen addition altered both the uptake and release of carbon dioxide from the forest floor, but the magnitude and direction of this effect depended on the time during the growing season and the amount of nitrogen added. Specifically, nitrogen addition stimulated net forest floor carbon uptake only in the late growing season. We find evidence for species-specific control of forest floor carbon sink strength, as photosynthesis per unit ground area was positively correlated only with the abundance of the vascular plant Vaccinium myrtillus and no others. Comparison of understorey vegetation photosynthesis and respiration from the study site indicates that understorey vegetation photosynthate was mainly supplying respiratory demands for much of the year. Only in the late season with nitrogen addition did understorey vegetation appear to experience a large surplus of carbon in excess of respiratory requirements. Further work, simultaneously comparing all major biomass and respiratory carbon fluxes in forest floor and tree vegetation, is required to resolve the likely impacts of environmental changes on whole-ecosystem carbon sequestration in boreal forests.

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

PLoS ONE ◽  
2012 ◽  
Vol 7 (9) ◽  
pp. e45205 ◽  
Author(s):  
Li Jiang ◽  
Rui Guo ◽  
Tingcheng Zhu ◽  
Xuedun Niu ◽  
Jixun Guo ◽  
...  
Keyword(s):  
Northeast China ◽  
Carbon Fluxes ◽  
Nitrogen Addition ◽  
Ecosystem Carbon ◽  
Ecosystem Carbon Fluxes

Effects of Nitrogen Deposition on Ecosystem Carbon Fluxes in Sanjiang Plain Marsh of Northeastern China

2011 ◽  
Vol 71-78 ◽  
pp. 2957-2961
Author(s):  
Jian Bo Wang ◽  
Xiao Ling Fu ◽  
Hong Wei Ni ◽  
Xiao Liang Zhou
Keyword(s):  
Net Primary Productivity ◽  
Ecosystem Respiration ◽  
Growing Season ◽  
Carbon Fluxes ◽  
Sanjiang Plain ◽  
Northeastern China ◽  
Long Term Effects ◽  
Ecosystem Carbon ◽  
Ecosystem Carbon Fluxes

It has widely been demonstrated that nitrogen (N) addition enhances plant growth and net primary productivity of terrestrial ecosystems. Moreover, N enrichment could have a profound impact on ecosystem carbon fluxes, especially in the regions where N is deficient. However, there is still debate on how N affects net ecosystem CO2 exchange (NEE). A field experiment manipulating N has been conducted in Calamagrostis anagustifolia community of Sanjiang Plain marsh of northeastern China from 2009 to 2010. N was added at a rate of 5 and 10gN m -2 yr -1with NH4NO3. The results for the 2 yr showed that gross ecosystem productivity (GEP) was higher than ecosystem respiration, leading to net carbon(C)sink (measured by NEE) over the growing season in the study site. Furthermore, low nitrogen (LN) and high nitrogen (HN) addition all significantly stimulated growing-season NEE, on average, by 22 and 36%, respectively. It’s indicated that air temperature plays a major role in regulating ecosystem net C exchange and their responses to climatic change in Sanjiang Plain of northern China. we need long-term field studies to predict the long-term effects of N deposition on ecosystem processes.

Seasonal and interannual variability in13C composition of ecosystem carbon fluxes in the U.S. Southern Great Plains

Tellus B ◽  
2011 ◽  
Vol 63 (2) ◽  
Author(s):  
Margaret S. Torn ◽  
Sebastien C. Biraud ◽  
Christopher J. Still ◽  
William J. Riley ◽  
Joe A. Berry
Keyword(s):  
Interannual Variability ◽  
Great Plains ◽  
Carbon Fluxes ◽  
Southern Great Plains ◽  
Seasonal And Interannual Variability ◽  
Ecosystem Carbon ◽  
Ecosystem Carbon Fluxes ◽  
The U.S

Red spruce seedling gas exchange in response to elevated CO2, water stress, and soil fertility treatments

1994 ◽  
Vol 24 (5) ◽  
pp. 954-959 ◽  
Author(s):  
L.J. Samuelson ◽  
J.R. Seiler
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Soil Fertility ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Red Spruce ◽  
Fertility Treatment ◽  
Sink Strength ◽  
Growth Enhancement ◽  
Growing Seasons

The interactive influences of ambient (374 μL•L−1) or elevated (713 μL•L−1) CO2, low or high soil fertility, well-watered or water-stressed treatment, and rooting volume on gas exchange and growth were examined in red spruce (Picearubens Sarg.) grown from seed through two growing seasons. Leaf gas exchange throughout two growing seasons and growth after two growing seasons in response to elevated CO2 were independent of soil fertility and water-stress treatments, and rooting volume. During the first growing season, no reduction in leaf photosynthesis of seedlings grown in elevated CO2 compared with seedlings grown in ambient CO2 was observed when measured at the same CO2 concentration. During the second growing season, net photosynthesis was up to 21% lower for elevated CO2-grown seedlings than for ambient CO2-grown seedlings when measured at 358 μL•L−1. Thus, photosynthetic acclimation to growth in elevated CO2 occurred gradually and was not a function of root-sink strength or soil-fertility treatment. However, net photosynthesis of seedlings grown and measured at an elevated CO2 concentration was still over 2 times greater than the photosynthesis of seedlings grown and measured at an ambient CO2 concentration. Growth enhancement by CO2 was maintained, since seedlings grown in elevated CO2 were 40% larger in both size and weight after two growing seasons.

Nitrogen addition amplifies the nonlinear drought response of grassland productivity to extended growing‐season droughts

Ecology ◽  
2021 ◽  
Author(s):  
Bo Meng ◽  
Junqin Li ◽  
Gregory E. Maurer ◽  
Shangzhi Zhong ◽  
Yuan Yao ◽  
...  
Keyword(s):  
Growing Season ◽  
Nitrogen Addition ◽  
Drought Response ◽  
Grassland Productivity

scholarly journals Ozone deposition into a boreal forest over a decade of observations: evaluating deposition partitioning and driving variables

2012 ◽  
Vol 12 (24) ◽  
pp. 12165-12182 ◽  
Author(s):  
Ü. Rannik ◽  
N. Altimir ◽  
I. Mammarella ◽  
J. Bäck ◽  
J. Rinne ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Water Vapour ◽  
Environmental Variables ◽  
Total Ozone ◽  
Explanatory Power ◽  
Growing Season ◽  
Sink Strength ◽  
Ozone Deposition ◽  
Air Space ◽  
Flux Measurements

Abstract. This study scrutinizes a decade-long series of ozone deposition measurements in a boreal forest in search for the signature and relevance of the different deposition processes. The canopy-level ozone flux measurements were analysed for deposition characteristics and partitioning into stomatal and non-stomatal fractions, with the main focus on growing season day-time data. Ten years of measurements enabled the analysis of ozone deposition variation at different time-scales, including daily to inter-annual variation as well as the dependence on environmental variables and concentration of biogenic volatile organic compounds (BVOC-s). Stomatal deposition was estimated by using multi-layer canopy dispersion and optimal stomatal control modelling from simultaneous carbon dioxide and water vapour flux measurements, non-stomatal was inferred as residual. Also, utilising the big-leaf assumption stomatal conductance was inferred from water vapour fluxes for dry canopy conditions. The total ozone deposition was highest during the peak growing season (4 mm s−1) and lowest during winter dormancy (1 mm s−1). During the course of the growing season the fraction of the non-stomatal deposition of ozone was determined to vary from 26 to 44% during day time, increasing from the start of the season until the end of the growing season. By using multi-variate analysis it was determined that day-time total ozone deposition was mainly driven by photosynthetic capacity of the canopy, vapour pressure deficit (VPD), photosynthetically active radiation and monoterpene concentration. The multi-variate linear model explained the high portion of ozone deposition variance on daily average level (R2 = 0.79). The explanatory power of the multi-variate model for ozone non-stomatal deposition was much lower (R2 = 0.38). The set of common environmental variables and terpene concentrations used in multivariate analysis were able to predict the observed average seasonal variation in total and non-stomatal deposition but failed to explain the inter-annual differences, suggesting that some still unknown mechanisms might be involved in determining the inter-annual variability. Model calculation was performed to evaluate the potential sink strength of the chemical reactions of ozone with sesquiterpenes in the canopy air space, which revealed that sesquiterpenes in typical amounts at the site were unlikely to cause significant ozone loss in canopy air space. The results clearly showed the importance of several non-stomatal removal mechanisms. Unknown chemical compounds or processes correlating with monoterpene concentrations, including potentially reactions at the surfaces, contribute to non-stomatal sink term.

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