R. Aerts et H. De Caluwe, Nitrogen deposition effects on carbon dioxide and methane emissions from temperate peatland soils, OIKOS, 84(1), 1999, pp. 44-54
Northern peatlands are important sources of carbon dioxide and methane emis
sions to the atmosphere. Increased atmospheric N deposition may have a sign
ificant impact on the emission of these greenhouse gases. We studied CO2 an
d CH4 emissions from untreated temperate pc at soils from a eutrophic and a
mesotrophic Fen in a high N deposition area (the Netherlands) and from a m
esotrophic fen in a low N deposition area (north-cast Poland). In addition,
we investigated the effects of N, P and glucose amendments on the emission
s of CO2 and CH4 from these soils.
Nitrogen availability (extractable NH4+) in untreated pent from the high N
area was 2.5-7.5 times higher than in the low N area, whereas the pH was 0.
9-1.7 units lower. Using 6-week laboratory incubations of peat columns, we
found that mean daily CO2 emission from untreated peat soils from the high
N area was lower than that from the low N area. Both linear and multiple re
gression analysis shelved that CO2 emission was positively related to soil
pH (r(2) = 0.64). Additional N supply led to pn reduction and to lower CO2
emission, especially in the low N peat soils. Thus, increased atmospheric N
deposition lends, probably as a result of soil acidification, to fewer CO2
emission. Although glucose amendments resulted in increased CO2 and CH4 em
ission, we did not find evidence that this was caused by increased minerali
zation of native pest. Mean daily CH4-C emission was about 1-2 orders of ma
gnitude lower than mean daily CO2-C emission. In the untreated peat soils f
rom the high N eutrophic site, methane emission was higher than in the high
N mesotrophic site and in the low N mesotrophic site. Linear regression an
alysis showed a positive relation between methane emission and soil fertili
ty variables (r(2)=0.41-0.55), whereas a multiple regression model revealed
that methane emission was determined by N-related soil chemistry variables
(r(2) = 0.93). Increased nutrient supply initially resulted in higher meth
ane emission from soils of both mesotrophic sites, but there was no effect
on the high N eutrophic soil. These results show that increased atmospheric
N deposition leads to increased methane emission from low-fertility pent s
oils. However, the ultimate effect of atmospheric N deposition on trace gas
emissions and thereby on global warming is determined by the balance betwe
en the ratios of the change in CO2-C emission and CH4-C emission and the ra
tio of their global warming potentials (1:21).