Soil C mineralization and temperature sensitivity in alpine grasslands of the Qinghai-Xizang Plateau

doi:10.3724/SP.J.1258.2013.00102

Abstract

Abstract:

Aims Currently, the temperature sensitivity of soil carbon (C) mineralization and the factors that control it are the focus of studies on soil C cycle and global climate change. The main objectives of this study were to: (1) investigate the effects of temperature and land-use (fenced grassland vs. grazing grassland) on soil C mineralization and its temperature sensitivity (Q₁₀) in the grasslands of Qinghai-Xizang Plateau and (2) determine the relationships of the rate of soil C mineralization with soil properties (e.g. soil organic carbon content (SOC), soil total nitrogen content (STN)).
Methods Eleven pairs of plots (fenced sites vs. grazing sites) were selected along an east-west transect in northwest of Qinghai-Xizang Plateau. Soil samples were collected at a depth of 0-20 cm, to measure soil C mineralization rates under a temperature gradient (i.e. 5, 10, 15, 20, and 25 °C) in laboratory. Data for soil C mineralization rate on the 7th day and 56th day, respectively, were used to assess the short- and long-term effects.
Important findings Soil C mineralization rates declined from east to west on fenced sites, but varied slightly on the grazing sites. Soil C mineralization rates increased significantly with increasing incubation temperature, and were strongly related to SOC and STN; higher the SOC and STN, greater the accumulative soil C mineralization. Q₁₀ showed no apparent spatial pattern along the east-west transect, and was not susceptible to land-use with average Q₁₀values of 1.83 and 1.86 on the fenced sites and the grazing sites, respectively. Moreover, Q₁₀ was not correlated with either SOC or STN. Findings in this study provide new insights on the responses of soil C mineralization and its temperature sensitivity to land-use change on the Qinghai-Xizang Plateau, contributing important information for evaluating soil C sequestration and its response to warming scenarios in this region.

Key words: land use type, Q₁₀, Qinghai-Xizang Plateau, soil organic matter, spatial pattern, temperature sensitivity

XU Li,YU Shu-Xia,HE Nian-Peng,WEN Xue-Fa,SHI Pei-Li,ZHANG Yang-Jian,DAI Jing-Zhong,WANG Ruo-Meng. Soil C mineralization and temperature sensitivity in alpine grasslands of the Qinghai-Xizang Plateau[J]. Chin J Plant Ecol, 2013, 37(11): 988-997.

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URL: https://www.plant-ecology.com/EN/10.3724/SP.J.1258.2013.00102

https://www.plant-ecology.com/EN/Y2013/V37/I11/988

Figures/Tables 8

References 36

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实验样点 Experimental site	封育草地 Fenced grassland (FG)		自由放牧草地 Grazing grassland (GG)
实验样点 Experimental site	经度 Longitude (E)	纬度 Latitude (N)	经度 Longitude (E)	纬度 Latitude (N)
样点1 Site 1	91.973 1°	31.383 5°	91.962 4°	31.376 4°
样点2 Site 2	91.723 8°	31.619 2°	91.719 8°	31.608 2°
样点3 Site 3	91.907 8°	32.302 9°	91.910 5°	32.305 0°
样点4 Site 4	90.459 8°	31.364 4°	90.399 0°	31.374 5°
样点5 Site 5	90.055 3°	31.497 4°	90.055 6°	31.497 8°
样点6 Site 6	90.244 1°	31.391 1°	90.244 4°	31.391 4°
样点7 Site 7	86.653 3°	32.337 9°	86.653 6°	32.338 2°
样点8 Site 8	86.796 9°	31.752 9°	86.797 2°	31.753 2°
样点9 Site 9	85.839 5°	31.924 6°	85.840 0°	31.924 9°
样点10 Site 10	82.910 0°	32.380 9°	82.910 6°	32.381 2°
样点11 Site 11	81.828 2°	32.074 8°	81.828 4°	32.075 3°

实验样点 Experimental site	封育草地 Fenced grassland (FG)		自由放牧草地 Grazing grassland (GG)
实验样点 Experimental site	经度 Longitude (E)	纬度 Latitude (N)	经度 Longitude (E)	纬度 Latitude (N)
样点1 Site 1	91.973 1°	31.383 5°	91.962 4°	31.376 4°
样点2 Site 2	91.723 8°	31.619 2°	91.719 8°	31.608 2°
样点3 Site 3	91.907 8°	32.302 9°	91.910 5°	32.305 0°
样点4 Site 4	90.459 8°	31.364 4°	90.399 0°	31.374 5°
样点5 Site 5	90.055 3°	31.497 4°	90.055 6°	31.497 8°
样点6 Site 6	90.244 1°	31.391 1°	90.244 4°	31.391 4°
样点7 Site 7	86.653 3°	32.337 9°	86.653 6°	32.338 2°
样点8 Site 8	86.796 9°	31.752 9°	86.797 2°	31.753 2°
样点9 Site 9	85.839 5°	31.924 6°	85.840 0°	31.924 9°
样点10 Site 10	82.910 0°	32.380 9°	82.910 6°	32.381 2°
样点11 Site 11	81.828 2°	32.074 8°	81.828 4°	32.075 3°

实验样点 Experimental site	优势植被 Dominant vegetation	土地利用方式 Land-use type	有机碳含量 Organic carbon content (g·kg^-1)	全氮含量 Total nitrogen content (g·kg^-1)	pH
样点1 Site 1	高山嵩草	封育草地 Fenced grassland	19.04 ± 0.04^a	1.52 ± 0.02^a	8.04 ± 0.12^a
	Kobresia pygmaea	自由放牧草地 Grazing grassland	10.30 ± 0.01^b	0.94 ± 0.01^b	8.33 ± 0.36^a
样点2 Site 2	高山嵩草	封育草地 Fenced grassland	24.42 ± 0.08^a	1.91 ± 0.03^a	8.56 ± 0.52^a
	K. pygmaea	自由放牧草地 Grazing grassland	13.31 ± 0.02^b	1.21 ± 0.08^b	7.77 ± 0.48^a
样点3 Site 3	高山嵩草	封育草地 Fenced grassland	11.76 ± 0.01^a	1.05 ± 0.00^a	8.43 ± 0.05^a
	K. pygmaea	自由放牧草地 Grazing grassland	11.12 ± 0.01^b	1.13 ± 0.01^b	7.78 ± 0.41^a
样点4 Site 4	紫花针茅	封育草地 Fenced grassland	12.27 ± 0.03^a	1.18 ± 0.03^a	7.79 ± 0.57^a
	Stipa purpurea	自由放牧草地 Grazing grassland	10.23 ± 0.01^b	1.09 ± 0.03^b	8.38 ± 0.19^a
样点5 Site 5	紫花针茅和羊草	封育草地 Fenced grassland	10.31 ± 0.09^a	1.04 ± 0.04^a	9.07 ± 0.02^a
	S. purpurea and Leymus chinensis	自由放牧草地 Grazing grassland	8.92 ± 0.07^a	1.14 ± 0.05^b	8.53 ± 0.55^a
样点6 Site 6	紫花针茅	封育草地 Fenced grassland	8.96 ± 0.06^a	0.97 ± 0.01^a	7.83 ± 0.30^a
	S. purpurea	自由放牧草地 Grazing grassland	12.17 ± 0.03^b	1.21 ± 0.03^b	8.33 ± 0.22^a
样点7 Site 7	紫花针茅	封育草地 Fenced grassland	6.40 ± 0.16^a	0.71 ± 0.04^a	9.94 ± 0.01^a
	S. purpurea	自由放牧草地 Grazing grassland	3.95 ± 0.06^b	0.70 ± 0.03^a	10.09 ± 0.02^b
样点8 Site 8	紫花针茅	封育草地 Fenced grassland	13.36 ± 0.13^a	2.14 ± 0.05^a	8.73 ± 0.03^a
	S. purpurea	自由放牧草地 Grazing grassland	10.14 ± 0.13^b	1.39 ± 0.08^b	8.53 ± 0.03^b
样点9 Site 9	紫花针茅和薹草	封育草地 Fenced grassland	6.70 ± 0.31^a	0.99 ± 0.03^a	9.28 ± 0.03^a
	S. purpurea and Carex moorcroftii	自由放牧草地 Grazing grassland	6.91 ± 0.10^a	1.03 ± 0.09^a	8.94 ± 0.04^b
样点10 Site 10	沙生针茅和羽状针茅	封育草地 Fenced grassland	17.40 ± 0.13^a	1.23 ± 0.05^a	8.62 ± 0.09^a
	S. purpurea and S. pennata	自由放牧草地 Grazing grassland	11.89 ± 0.16^b	0.94 ± 0.02^b	8.82 ± 0.03^b
样点11 Site 11	沙生针茅和羽状针茅	封育草地 Fenced grassland	3.76 ± 0.31^a	0.59 ± 0.06^a	9.12 ± 0.01^a
	S. purpurea and S. pennata	自由放牧草地 Grazing grassland	6.55 ± 0.17^a	0.79 ± 0.06^b	9.05 ± 0.03^b

实验样点 Experimental site	优势植被 Dominant vegetation	土地利用方式 Land-use type	有机碳含量 Organic carbon content (g·kg^-1)	全氮含量 Total nitrogen content (g·kg^-1)	pH
样点1 Site 1	高山嵩草	封育草地 Fenced grassland	19.04 ± 0.04^a	1.52 ± 0.02^a	8.04 ± 0.12^a
	Kobresia pygmaea	自由放牧草地 Grazing grassland	10.30 ± 0.01^b	0.94 ± 0.01^b	8.33 ± 0.36^a
样点2 Site 2	高山嵩草	封育草地 Fenced grassland	24.42 ± 0.08^a	1.91 ± 0.03^a	8.56 ± 0.52^a
	K. pygmaea	自由放牧草地 Grazing grassland	13.31 ± 0.02^b	1.21 ± 0.08^b	7.77 ± 0.48^a
样点3 Site 3	高山嵩草	封育草地 Fenced grassland	11.76 ± 0.01^a	1.05 ± 0.00^a	8.43 ± 0.05^a
	K. pygmaea	自由放牧草地 Grazing grassland	11.12 ± 0.01^b	1.13 ± 0.01^b	7.78 ± 0.41^a
样点4 Site 4	紫花针茅	封育草地 Fenced grassland	12.27 ± 0.03^a	1.18 ± 0.03^a	7.79 ± 0.57^a
	Stipa purpurea	自由放牧草地 Grazing grassland	10.23 ± 0.01^b	1.09 ± 0.03^b	8.38 ± 0.19^a
样点5 Site 5	紫花针茅和羊草	封育草地 Fenced grassland	10.31 ± 0.09^a	1.04 ± 0.04^a	9.07 ± 0.02^a
	S. purpurea and Leymus chinensis	自由放牧草地 Grazing grassland	8.92 ± 0.07^a	1.14 ± 0.05^b	8.53 ± 0.55^a
样点6 Site 6	紫花针茅	封育草地 Fenced grassland	8.96 ± 0.06^a	0.97 ± 0.01^a	7.83 ± 0.30^a
	S. purpurea	自由放牧草地 Grazing grassland	12.17 ± 0.03^b	1.21 ± 0.03^b	8.33 ± 0.22^a
样点7 Site 7	紫花针茅	封育草地 Fenced grassland	6.40 ± 0.16^a	0.71 ± 0.04^a	9.94 ± 0.01^a
	S. purpurea	自由放牧草地 Grazing grassland	3.95 ± 0.06^b	0.70 ± 0.03^a	10.09 ± 0.02^b
样点8 Site 8	紫花针茅	封育草地 Fenced grassland	13.36 ± 0.13^a	2.14 ± 0.05^a	8.73 ± 0.03^a
	S. purpurea	自由放牧草地 Grazing grassland	10.14 ± 0.13^b	1.39 ± 0.08^b	8.53 ± 0.03^b
样点9 Site 9	紫花针茅和薹草	封育草地 Fenced grassland	6.70 ± 0.31^a	0.99 ± 0.03^a	9.28 ± 0.03^a
	S. purpurea and Carex moorcroftii	自由放牧草地 Grazing grassland	6.91 ± 0.10^a	1.03 ± 0.09^a	8.94 ± 0.04^b
样点10 Site 10	沙生针茅和羽状针茅	封育草地 Fenced grassland	17.40 ± 0.13^a	1.23 ± 0.05^a	8.62 ± 0.09^a
	S. purpurea and S. pennata	自由放牧草地 Grazing grassland	11.89 ± 0.16^b	0.94 ± 0.02^b	8.82 ± 0.03^b
样点11 Site 11	沙生针茅和羽状针茅	封育草地 Fenced grassland	3.76 ± 0.31^a	0.59 ± 0.06^a	9.12 ± 0.01^a
	S. purpurea and S. pennata	自由放牧草地 Grazing grassland	6.55 ± 0.17^a	0.79 ± 0.06^b	9.05 ± 0.03^b

样点 Site	培养7天		培养56天
	Incubation for 7 d		Incubation for 56 d
	D 值	p值	D 值	p值
	D value	p value	D value	p value
	(μg C·g^-1soil)		(μg C·g^-1soil)
样点1 Site 1	25.92	0.023	148.99	0.012
样点2 Site 2	39.38	0.02	218.41	0.018
样点3 Site 3	-0.63	0.8	-41.79	0.091
样点4 Site 4	7.68	0.008	50.23	0.011
样点5 Site 5	9.96	0.003	70.45	0.006
样点6 Site 6	-9.81	0.01	-85.59	0.003
样点7 Site 7	1.7	0.047	31.94	0.123
样点8 Site 8	3.75	0.325	69.53	0.005
样点9 Site 9	5.75	0.064	58.81	0.009
样点10 Site 10	15.86	0	63.21	0.009
样点11 Site 11	-8.36	0.024	-80.58	0.012