Fluxes of N2O, CH4 and CO2 in a meadow ecosystem exposed to elevated ozone and carbon dioxide for three years

Influence of increasing temperature and nitrogen input on greenhouse gas emissions from a desert steppe soil in Inner Mongolia

“…The small variations (ranging from 0.319 to 0.338 mL L ) soil (Ullah et al 2005;Kanerva et al 2007), but greater than that reported for shortgrass steppe soil (1.9 mg N m À2 h À1 ; Mosier et al 1997). The highest N 2 O emission occurred during the spring, most likely when freeze-thawing occurred (Table 5).…”

Multifactor controls on terrestrial N<sub>2</sub>O flux over North America from 1979 through 2010

“…For example, nitrogen (N) input may stimulate N 2 O production by increasing substrate availability (Kettunen et al, 2005;Mcswiney and Robertson, 2005); elevated atmospheric CO 2 may reduce N availability in soil owing to progressive N accumulation in plant biomass McGuire et al, 1995), which inhibit the N 2 O emission (Phillips et al, 2001); alternatively, elevated atmospheric CO 2 might increase photosynthetic products and stimulate microbial process, and thus increase N 2 O emission (Kettunen et al, 2005;Ineson et al, 1998). If these two effects are counterbalanced, it may appear as neutral response of N 2 O flux to elevated atmospheric CO 2 (Kanerva et al, 2007;Ambus and Robertson, 1999). Tropospheric O 3 pollution may alter microbial community (Kanerva et al, 2008) and cause an increase or decrease in N 2 O emission, depending on time and location (Kanerva et al, 2007).…”

“…If these two effects are counterbalanced, it may appear as neutral response of N 2 O flux to elevated atmospheric CO 2 (Kanerva et al, 2007;Ambus and Robertson, 1999). Tropospheric O 3 pollution may alter microbial community (Kanerva et al, 2008) and cause an increase or decrease in N 2 O emission, depending on time and location (Kanerva et al, 2007). By comparison, the effects of climate variability and land conversion on the N 2 O emission are more complicated, largely replying upon the specific site condition (Jiang et al, 2009;Goldberg and Gebauer, 2009;Zhang et al, 2007b).…”

“…N 2 O flux has been recognized as a result of a suite of microbial processes influenced by a variety of environmental factors (Conrad, 1996;Williams et al, 1992;Pilegaard et al, 2006). Global change will alter these environmental factors and substrates, and further change the N 2 O flux (Bouwman et al, 1993;Conrad, 1996;Goldberg and Gebauer, 2009;Kanerva et al, 2007;Kettunen et al, 2005;Williams et al, 1992;Ambus and Robertson, 1999). For example, nitrogen (N) input may stimulate N 2 O production by increasing substrate availability (Kettunen et al, 2005;Mcswiney and Robertson, 2005); elevated atmospheric CO 2 may reduce N availability in soil owing to progressive N accumulation in plant biomass McGuire et al, 1995), which inhibit the N 2 O emission (Phillips et al, 2001); alternatively, elevated atmospheric CO 2 might increase photosynthetic products and stimulate microbial process, and thus increase N 2 O emission (Kettunen et al, 2005;Ineson et al, 1998).…”

How does elevated ozone reduce methane emissions from peatlands?

“…This may be through reduced litter quantity or quality, although effects of O 3 on nitrification, denitrification, microbial biomass and plant uptake of N have also been reported (Wittig et al, 2009;Li et al 2010;Bhatia et al, 2011;Pereira et al, 2011;Bassin et al, 2015). In nitrogen (N) poor systems such as peatlands, reduced below-ground allocation of N could cause reduced activity of heterotrophic soil microorganisms, such as methanogens (Kanerva et al, 2007). However, lower availability of ammonium (NH 4 ), the dominant form of inorganic N in peatlands, could also promote methanotrophic activity (Keller et al, 2006), and O 3 has been reported to reduce soil NH 4 concentrations in meadows (Kanerva et al (2006) and soybean crops (Pereira et al, 2011).…”