Effect of nitrogen deposition on soil respiration in Phragmites australis wetland in the Yellow River Delta, China

doi:10.3724/SP.J.1258.2013.00053

Abstract

Abstract:

Aims Atmospheric nitrogen deposition derived from fossil-fuel combustion, fertilization, land clearing and biomass burning is occurring over almost the entire world. As an important ecosystem, wetland in industrialized regions has experienced greater rates of nitrogen deposition in recent decades. Our objectives were to determine the effect of increased nitrogen deposition on the diurnal and seasonal variation of soil respiration in a reed (Phragmites australis) wetland and to relate the variation to environmental and biological factors.
Methods From June to October 2012, we conducted a simulated nitrogen deposition field experiment in a reed wetland in the Yellow River Delta, China. The levels of nitrogen deposition were control (CK), low nitrogen (LN) and high nitrogen (HN) with 0, 50 and 100 kg N·hm^-2·a^-1, respectively. Soil respiration was measured during the growing season by using a LI-8100 soil CO₂ efflux system.
Important findings Nitrogen deposition promoted soil respiration in the reed wetland during the entire growing season. Compared with CK, the LN and HN treatments increased the average rates of soil respiration by 19% and 58%, respectively. Surface ponding had a significant effect on the diurnal variation patterns of soil respiration. When there was no surface ponding, the diurnal variation of soil respiration in different treatments all showed “a unimodal” pattern. When surface ponding occurred, the diurnal variation of soil respiration did not show a unimodal pattern or the peak value of soil respiration rate was delayed. In addition, response of soil respiration to air temperature was affected by surface ponding. When there was no surface ponding, soil respiration exhibited a significantly positive exponential relationship with air temperature, which explained 69.9%, 64.5% and 59.9% of the seasonal variation of soil respiration in CK, LN and HN, respectively. However, there was no significant relationship between soil respiration and air temperature when surface ponding occurred. The Q₁₀ (temperature sensitivity coefficients of soil respiration) of CK, LN and HN were 1.68, 1.75 and 1.68, respectively, suggesting that low nitrogen deposition increases the temperature sensitivity of soil respiration and high nitrogen deposition has no significant influence on it.

Key words: nitrogen deposition, reed wetland, soil respiration, Yellow River Delta

ZHU Min,ZHANG Zhen-Hua,YU Jun-Bao,WU Li-Xin,HAN Guang-Xuan,YANG Li-Qiong,XING Qing-Hui,XIE Bao-Hua,MAO Pei-Li,WANG Guang-Mei. Effect of nitrogen deposition on soil respiration in Phragmites australis wetland in the Yellow River Delta, China[J]. Chin J Plant Ecol, 2013, 37(6): 517-529.

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Figures/Tables 12

References 57

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处理 Treatment	土壤深度 Soil depth (cm)	铵态氮 Ammonium nitrogen (%)	硝态氮 Nitrate nitrogen (%)	全氮 Total nitrogen (%)	全碳 Total carbon (%)	有机碳 Organic carbon (%)
CK	0-10	1.19 ± 0.11^b	0.76 ± 0.18^a	0.06 ± 0.00^ab	1.57 ± 0.02^ab	0.42 ± 0.04^c
LN	0-10	2.00 ± 0.12^a	1.85 ± 0.67^a	0.08 ± 0.01^a	1.89 ± 0.13^a	0.98 ± 0.07^a
HN	0-10	2.13 ± 0.22^a	2.01 ± 0.88^a	0.09 ± 0.00^a	1.71 ± 0.10^a	0.84 ± 0.03^b
CK	10-20	1.12 ± 0.09^b	0.60 ± 0.08^a	0.05 ± 0.01^ab	1.38 ± 0.05^b	0.30 ± 0.03^c
LN	10-20	1.92 ± 0.24^a	1.08 ± 0.34^a	0.07 ± 0.01^a	1.80 ± 0.05^a	0.84 ± 0.03^a
HN	10-20	1.81 ± 0.15^a	0.92 ± 0.24^a	0.09 ± 0.01^a	1.85 ± 0.13^a	0.69 ± 0.04^b

处理 Treatment	土壤深度 Soil depth (cm)	铵态氮 Ammonium nitrogen (%)	硝态氮 Nitrate nitrogen (%)	全氮 Total nitrogen (%)	全碳 Total carbon (%)	有机碳 Organic carbon (%)
CK	0-10	1.19 ± 0.11^b	0.76 ± 0.18^a	0.06 ± 0.00^ab	1.57 ± 0.02^ab	0.42 ± 0.04^c
LN	0-10	2.00 ± 0.12^a	1.85 ± 0.67^a	0.08 ± 0.01^a	1.89 ± 0.13^a	0.98 ± 0.07^a
HN	0-10	2.13 ± 0.22^a	2.01 ± 0.88^a	0.09 ± 0.00^a	1.71 ± 0.10^a	0.84 ± 0.03^b
CK	10-20	1.12 ± 0.09^b	0.60 ± 0.08^a	0.05 ± 0.01^ab	1.38 ± 0.05^b	0.30 ± 0.03^c
LN	10-20	1.92 ± 0.24^a	1.08 ± 0.34^a	0.07 ± 0.01^a	1.80 ± 0.05^a	0.84 ± 0.03^a
HN	10-20	1.81 ± 0.15^a	0.92 ± 0.24^a	0.09 ± 0.01^a	1.85 ± 0.13^a	0.69 ± 0.04^b

月份 Month	CK (μmol CO₂·m^-2·s^-1)	LN (μmol CO₂·m^-2·s^-1)	HN (μmol CO₂·m^-2·s^-1)
6月 June	1.95 ± 0.13^b	1.95 ± 0.16^b	2.68 ± 0.18^a
7月 July	1.65 ± 0.09^ab	2.23 ± 0.32^a	2.78 ± 0.35^a
9月 September	2.11 ± 0.09^c	2.57 ± 0.09^b	3.33 ± 0.11^a
10月 October	1.19 ± 0.09^b	1.50 ± 0.12^b	2.13 ± 0.20^a
生长季 Growing season	1.67 ± 0.15^b	1.99 ± 0.17^b	2.64 ± 0.21^a

月份 Month	CK (μmol CO₂·m^-2·s^-1)	LN (μmol CO₂·m^-2·s^-1)	HN (μmol CO₂·m^-2·s^-1)
6月 June	1.95 ± 0.13^b	1.95 ± 0.16^b	2.68 ± 0.18^a
7月 July	1.65 ± 0.09^ab	2.23 ± 0.32^a	2.78 ± 0.35^a
9月 September	2.11 ± 0.09^c	2.57 ± 0.09^b	3.33 ± 0.11^a
10月 October	1.19 ± 0.09^b	1.50 ± 0.12^b	2.13 ± 0.20^a
生长季 Growing season	1.67 ± 0.15^b	1.99 ± 0.17^b	2.64 ± 0.21^a

处理 Treatment	气温 Air temperature (℃)	土壤温度 Soil temperature (℃)
处理 Treatment	气温 Air temperature (℃)	5 cm	10 cm	20 cm
CK	0.836^**	0.803^**	0.767^**	0.742^**
LN	0.744^**	0.551^**	0.515^**	0.505^**
HN	0.725^**	0.535^**	0.499^**	0.501^**