SPECIAL FEATURE
Climate Change and Biodiversity Conservation in East Asia
as a token of memory for the 7th EAFES in Daegu, Korea
Huai Yang
•
Shirong Liu
•
Yide Li
•
Han Xu
Diurnal variations and gap effects of soil CO
2
,N
2
O and CH
4
fluxes in a
typical tropical montane rainforest in Hainan Island, China
Received: 31 January 2017 / Accepted: 5 December 2017 / Published online: 26 December 2017
Ó The Ecological Society of Japan 2017
Abstract Accurate estimations of soil greenhouse gas
(GHG) fluxes in tropical montane rainforests are critical
for assessing the role of tropical forests in influencing
global climate change. This research aimed to determine
the diurnal variation in soil GHG fluxes and understand
the effects of forest canopy gaps on GHG fluxes, and
their major controlling factors. The diurnal fluxes of soil
carbon dioxide (CO
2
), nitrous oxide (N
2
O) and methane
(CH
4
) inside and outside three forest canopy gaps in a
tropical montane rainforest were measured with a closed
static chamber system in June 2015. The main results are
as follows. (1) There was an obvious single-peak daily
variation of soil GHG fluxes. (2) The averaged soil CO
2
,
N
2
OandCH
4
fluxes of the whole day were closest to the
daily average emission fluxes at 9:00 and 12:00 for CO
2
,
6:00 and 9:00 for N
2
O, and 9:00 and 12:00 for CH
4
,
respectively. (3) Soil CO
2
and N
2
O emissions (positive
values) and CH
4
uptake (negative values) were higher
inside gaps than outside. (4) There were stronger expo-
nential relationships between soil CO
2
and N
2
O emis-
sions and temperature inside gaps than outside, and
there was a stronger quadratic relationship between CH
4
uptake and temperature outside gaps than inside.
However, significant relationships between soil CO
2
(or
CH
4
) and soil moisture only occurred inside gaps
(P < 0.01). There were clear diurnal variations and
significant effects of gaps on soil CO
2
,N
2
O and CH
4
fluxes. Our study indicated that understanding the dif-
ferent diurnal variations of soil CO
2
,N
2
OandCH
4
fluxes inside and outside canopy gaps could improve the
accurate evaluation of soil GHG fluxes in tropical
montane rainforests under a changing climate.
Keywords Soil greenhouse gases fluxes Æ Diurnal
variation Æ Forest canopy gap Æ Tropical montane
rainforest Æ Soil temperature
Introduction
Carbon dioxide (CO
2
), methane (CH
4
) and nitrous oxide
(N
2
O) are key radiatively active greenhouse gases
(GHGs) contributing to global warming (Stocker 2014).
Forest soils are the main natural source or sink of these
GHGs. Soil CO
2
efflux is an important component of
the carbon (C) cycle in forests and contributes 50–95%
of total ecosystem respiration (Janssens et al. 2001;
Yuste et al. 2005). Emissions of N
2
O from tropical
rainforest soils are 2.2–3.7 Tg N
2
O-nitrogen (N) year
À1
,
accounting for 24% of the global atmospheric N
2
O
budget (Prather et al. 2001). In addition, forest soils are
recognized as the most efficient sinks for atmospheric
CH
4
(Le Mer and Roger 2001). Humid tropical forests
cover an estimated 1150 ± 54 Mha (11.8%) of the
global land surface (Achard et al. 2002). The annual soil
GHG emissions in humid tropical forests, if accurately
estimated and simulated, could be used in predicting and
simulating future climate change. However, the esti-
mates of GHG emissions in tropical forest soil are cur-
rently uncertain (Mutuo et al. 2005; Gibbs et al. 2007),
mainly because of the lack of field observation data for
nighttime as a result of the difficulties in taking field
measurements during the night. Thus, field measure-
ments during both day and night are urgently needed to
improve our ability to estimate the source strength of
tropical rainforest soils for GHGs.
The in situ measurements of soil CO
2
,N
2
O and CH
4
fluxes of tropical rainforests are of great importance to
H. Yang Æ S. Liu (&)
International Center for Bamboo and Rattan, Beijing 100102,
People’s Republic of China
E-mail: liusr@caf.ac.cn
Tel.: 86-10-62889311
S. Liu
Key Laboratory of Forest Ecology and Environment, State For-
estry Administration, Institute of Forest Ecology, Environment
and Protection, Chinese Academy of Forestry, Beijing 100091,
People’s Republic of China
Y. Li Æ H. Xu
Research Institute of Tropical Forestry, Chinese Academy of
Forestry, Guangzhou 510520, People’s Republic of China
Ecol Res (2018) 33: 379–392
DOI 10.1007/s11284-017-1550-4
@Phil_Robichaud
@deepthiw
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