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Response of aboveground biomass and diversity to nitrogen addition along a degradation gradient in the Inner Mongolian steppe, China.

Xu X, Liu H, Song Z, Wang W, Hu G, Qi Z - Sci Rep (2015)

Bottom Line: Fields with a higher level of degradation tended to have a higher saturation value (20 g N m(-2) yr(-1)) than those with a lower degradation level ( < 10 g N m(-2) yr(-1)).After three years of experimentation, species richness showed little change across degradation levels.Among the four functional groups of grasses, sedges, forbs and legumes, grasses shared the most similar response patterns with those of the whole community, demonstrating the predominant role that they play in the restoration of grassland under a stimulus of nitrogen addition.

View Article: PubMed Central - PubMed

Affiliation: College of Urban and Environmental Sciences and MOE Laboratory for Earth Surface Processes, Peking University, Beijing, 100871, China.

ABSTRACT
Although nitrogen addition and recovery from degradation can both promote production of grassland biomass, these two factors have rarely been investigated in combination. In this study, we established a field experiment with six N-treatment (CK, 10, 20, 30, 40, 50 g N m(-2) yr(-1)) on five fields with different degradation levels in the Inner Mongolian steppe of China from 2011-2013. Our observations showed that while the external nitrogen increased the aboveground biomass in all five grasslands, the magnitude of the effects differed with the severity of degradation. Fields with a higher level of degradation tended to have a higher saturation value (20 g N m(-2) yr(-1)) than those with a lower degradation level ( < 10 g N m(-2) yr(-1)). After three years of experimentation, species richness showed little change across degradation levels. Among the four functional groups of grasses, sedges, forbs and legumes, grasses shared the most similar response patterns with those of the whole community, demonstrating the predominant role that they play in the restoration of grassland under a stimulus of nitrogen addition.

No MeSH data available.


Related in: MedlinePlus

Response of total aboveground biomass to the nitrogen addition. AF = abandoned farmland, ED = extremely degraded grassland, SD = severely degraded grassland, MD = moderately degraded grassland, MG = mature grassland. Bars with the same letter (e.g., a, b) were not significantly different in tests of S-N-K. Regression parameters were estimated with N treatment in each graph. Significant differences are reported as NS, P > 0.05; *, P < 0.05; **, P < 0.01; ***, P < 0.001. The error bars indicate the standard deviation.
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f1: Response of total aboveground biomass to the nitrogen addition. AF = abandoned farmland, ED = extremely degraded grassland, SD = severely degraded grassland, MD = moderately degraded grassland, MG = mature grassland. Bars with the same letter (e.g., a, b) were not significantly different in tests of S-N-K. Regression parameters were estimated with N treatment in each graph. Significant differences are reported as NS, P > 0.05; *, P < 0.05; **, P < 0.01; ***, P < 0.001. The error bars indicate the standard deviation.

Mentions: Biomass generally increased with increased N-treatment in all fields, as indicated by the positive slope values. Moreover, the slopes increased with the level of degradation (P = 0.007), especially in 2012. Biomass in AF (abandoned farmland, with the most severe degradation) increased most notably, with the greatest slopes being observed in the first two years. Although the general slope of AF decreased in 2013, the slope of the lower N-treatment (from CK to N-20) was still very large, reaching 30.53. In SD (severe degradation) and ED (extremely severe degradation), biomass increased with N-treatment throughout the three-year experimental period. The MD (moderate degradation) responded least significantly, with slopes remaining very close to 0 until 2013. For MG (mature grassland), the slopes were positive in 2011, but became negative in 2012 and 2013. Although the biomass of MG increased with the addition of nitrogen between N-0 and N-30 (with large slopes of 10.20 and 5.23) in 2012 and 2013, biomass decreased when nitrogen addition reached N-40 (Fig. 1).


Response of aboveground biomass and diversity to nitrogen addition along a degradation gradient in the Inner Mongolian steppe, China.

Xu X, Liu H, Song Z, Wang W, Hu G, Qi Z - Sci Rep (2015)

Response of total aboveground biomass to the nitrogen addition. AF = abandoned farmland, ED = extremely degraded grassland, SD = severely degraded grassland, MD = moderately degraded grassland, MG = mature grassland. Bars with the same letter (e.g., a, b) were not significantly different in tests of S-N-K. Regression parameters were estimated with N treatment in each graph. Significant differences are reported as NS, P > 0.05; *, P < 0.05; **, P < 0.01; ***, P < 0.001. The error bars indicate the standard deviation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508527&req=5

f1: Response of total aboveground biomass to the nitrogen addition. AF = abandoned farmland, ED = extremely degraded grassland, SD = severely degraded grassland, MD = moderately degraded grassland, MG = mature grassland. Bars with the same letter (e.g., a, b) were not significantly different in tests of S-N-K. Regression parameters were estimated with N treatment in each graph. Significant differences are reported as NS, P > 0.05; *, P < 0.05; **, P < 0.01; ***, P < 0.001. The error bars indicate the standard deviation.
Mentions: Biomass generally increased with increased N-treatment in all fields, as indicated by the positive slope values. Moreover, the slopes increased with the level of degradation (P = 0.007), especially in 2012. Biomass in AF (abandoned farmland, with the most severe degradation) increased most notably, with the greatest slopes being observed in the first two years. Although the general slope of AF decreased in 2013, the slope of the lower N-treatment (from CK to N-20) was still very large, reaching 30.53. In SD (severe degradation) and ED (extremely severe degradation), biomass increased with N-treatment throughout the three-year experimental period. The MD (moderate degradation) responded least significantly, with slopes remaining very close to 0 until 2013. For MG (mature grassland), the slopes were positive in 2011, but became negative in 2012 and 2013. Although the biomass of MG increased with the addition of nitrogen between N-0 and N-30 (with large slopes of 10.20 and 5.23) in 2012 and 2013, biomass decreased when nitrogen addition reached N-40 (Fig. 1).

Bottom Line: Fields with a higher level of degradation tended to have a higher saturation value (20 g N m(-2) yr(-1)) than those with a lower degradation level ( < 10 g N m(-2) yr(-1)).After three years of experimentation, species richness showed little change across degradation levels.Among the four functional groups of grasses, sedges, forbs and legumes, grasses shared the most similar response patterns with those of the whole community, demonstrating the predominant role that they play in the restoration of grassland under a stimulus of nitrogen addition.

View Article: PubMed Central - PubMed

Affiliation: College of Urban and Environmental Sciences and MOE Laboratory for Earth Surface Processes, Peking University, Beijing, 100871, China.

ABSTRACT
Although nitrogen addition and recovery from degradation can both promote production of grassland biomass, these two factors have rarely been investigated in combination. In this study, we established a field experiment with six N-treatment (CK, 10, 20, 30, 40, 50 g N m(-2) yr(-1)) on five fields with different degradation levels in the Inner Mongolian steppe of China from 2011-2013. Our observations showed that while the external nitrogen increased the aboveground biomass in all five grasslands, the magnitude of the effects differed with the severity of degradation. Fields with a higher level of degradation tended to have a higher saturation value (20 g N m(-2) yr(-1)) than those with a lower degradation level ( < 10 g N m(-2) yr(-1)). After three years of experimentation, species richness showed little change across degradation levels. Among the four functional groups of grasses, sedges, forbs and legumes, grasses shared the most similar response patterns with those of the whole community, demonstrating the predominant role that they play in the restoration of grassland under a stimulus of nitrogen addition.

No MeSH data available.


Related in: MedlinePlus