Effects of grazing on total nitrogen and stable nitrogen isotopes of plants and soil in different types of grasslands in Inner Mongolia

doi:10.11686/cyxb2020149

Abstract

Abstract:

In order to explore the effect of overgrazing on nitrogen （N） cycling in different grassland ecosystems， we selected three main types of grassland （meadow grassland， typical grassland and desert grassland） in Inner Mongolia， northern China， and analyzed the effects of long-term overgrazing on plant biomass， total nitrogen （TN） and stable nitrogen isotope （δ¹⁵N） values in plant leaves， roots and soil. The results showed that overgrazing significantly reduced the aboveground and underground biomass of grassland vegetation （P<0.05）. Under zero grazing conditions， the TN and δ¹⁵N values of leaves， roots and soil samples from the three main types of grassland showed a downward trend from east to west， and the TN and δ¹⁵N of plant leaves （R²=0.73， P<0.001） and roots （R²=0.86， P<0.001） showed significant positive correlation in all cases. Overgrazing reduced the values of TN and δ¹⁵N in the plant leaves， roots and soil of the three grassland types. In summary， overgrazing has caused substantive impact on N cycling in all three grassland types studied， so we recommend adoption of diversified management methods to ensure sustainable grassland ecosystem development.

Key words: grassland type, overgrazing, vegetation biomass, total nitrogen, stable nitrogen isotope

Guang-yi LV, Xue-bao XU, Cui-ping GAO, Zhi-hui YU, Xin-ya WANG, Cheng-jie WANG. Effects of grazing on total nitrogen and stable nitrogen isotopes of plants and soil in different types of grasslands in Inner Mongolia[J]. Acta Prataculturae Sinica, 2021, 30(3): 208-214.

Figures/Tables 7

References 23

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指标 Index	荒漠草原Desert steppe		典型草原Typical steppe		草甸草原Meadow steppe
指标 Index	无牧NG	重度放牧HG	无牧NG	重度放牧HG	无牧NG	重度放牧HG
全氮TN (%)	2.45±0.24a	2.40±0.25a	1.83±0.44a	1.47±0.07a	3.59±0.27a	1.33±0.60b
稳定氮同位素δ¹⁵N (‰)	0.77±0.44a	0.34±0.24a	-0.85±0.19a	-1.14±0.24a	3.72±0.79a	-1.98±0.59b

指标 Index	荒漠草原Desert steppe		典型草原Typical steppe		草甸草原Meadow steppe
指标 Index	无牧NG	重度放牧HG	无牧NG	重度放牧HG	无牧NG	重度放牧HG
全氮TN (%)	2.45±0.24a	2.40±0.25a	1.83±0.44a	1.47±0.07a	3.59±0.27a	1.33±0.60b
稳定氮同位素δ¹⁵N (‰)	0.77±0.44a	0.34±0.24a	-0.85±0.19a	-1.14±0.24a	3.72±0.79a	-1.98±0.59b

指标 Index	荒漠草原Desert steppe		典型草原Typical steppe		草甸草原Meadow steppe
指标 Index	无牧NG	重度放牧HG	无牧NG	重度放牧HG	无牧NG	重度放牧HG
全氮TN (%)	0.15±0.01a	0.14±0.01a	0.19±0.03a	0.18±0.02a	0.31±0.04a	0.13±0.01b
稳定氮同位素 δ¹⁵N (‰)	3.48±0.24a	3.27±0.22a	4.38±0.34a	3.23±0.19b	4.31±0.22a	3.32±0.46b

指标 Index	荒漠草原Desert steppe		典型草原Typical steppe		草甸草原Meadow steppe
指标 Index	无牧NG	重度放牧HG	无牧NG	重度放牧HG	无牧NG	重度放牧HG
全氮TN (%)	0.15±0.01a	0.14±0.01a	0.19±0.03a	0.18±0.02a	0.31±0.04a	0.13±0.01b
稳定氮同位素 δ¹⁵N (‰)	3.48±0.24a	3.27±0.22a	4.38±0.34a	3.23±0.19b	4.31±0.22a	3.32±0.46b

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