How do water table drawdown, duration of drainage and warming influence
greenhouse gas emissions from drained peatlands of the Zoige Plateau?
Abstract
As an important soil carbon pool in Qinghai-Tibet Plateau (QTP), alpine
peatland are extremely sensitive to global change. Duration of drainage
and water table drawdown lead to rapid soil degradation and C losses,
and this may worsen under warming as the soils are no longer protected
by anaerobic conditions. Hence, the objective of this study was to
assess the effect of drainage on microbial characteristics, greenhouse
gas (GHG) emissions and their influencing factors, and further analyze
whether the the variability of GHG emissions increases with warming. The
results showed that the influence of water table drawdown on microbial
community structure was greater than that of duration of drainage. Both
the fungal and prokaryotic community compositions varied with water
table gradient, and soil microbiota may served as a biomarker to analyze
the differences in GHG emissions among three different water table
treatments. Intriguingly, the GHG emission decreased with the increase
of drainage age, while water table drawdown reduced the CO2 and CH4
emission rates, and increased N2O emission rates. In addition, high
temperature increased CO2 by 75% and N2O by 42%, but not significantly
decreased the CH4 emission rates. Structural equation modeling suggested
that microbial community composition was the primary factor affecting
GHG emissions from drained peatlands, especially prokaryotes. Overall,
our results indicate that water table plays a more important role in GHG
emissions than duration of drainage, and the variability of GHG
emissions increases with warming.