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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.


Response of the percentage of aboveground biomass of different functional groups to the nitrogen addition. AF = abandoned farmland, ED = extremely degraded grassland, SD = severely degraded grassland, MD = moderately degraded grassland, MG = mature grassland. The different colors showed in the figure represent the percentage of each functional group in the total aboveground biomass.
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f2: Response of the percentage of aboveground biomass of different functional groups to the nitrogen addition. AF = abandoned farmland, ED = extremely degraded grassland, SD = severely degraded grassland, MD = moderately degraded grassland, MG = mature grassland. The different colors showed in the figure represent the percentage of each functional group in the total aboveground biomass.

Mentions: The biomass of the grass group showed a significantly greater increase with nitrogen addition than that of other functional groups. Although the aboveground biomass of sedges and legumes changed during the three years (Table S1), this change had little influence on the total biomass because of their low proportion (Fig. 2). The grass group showed positive slopes, while the other groups showed negative or non-significant slopes (Table S2). The trend in the grass group was similar to that of the total biomass, which was more obvious in the degraded grassland than in the mature grassland. In AF, ED and SD, after a year of nitrogen addition the dominance of the grass group was enhanced. In the third year, this phenomenon also occurred in MD. However, MG showed the opposite trend. Nevertheless, the biomass of grass in all fields during all years increased with increasing N-treatment. In contrast, the biomass of legumes decreased significantly and the biomass of sedges and forbs showed no clear trend (Fig. 3, Table S2).


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 the percentage of aboveground biomass of different functional groups to the nitrogen addition. AF = abandoned farmland, ED = extremely degraded grassland, SD = severely degraded grassland, MD = moderately degraded grassland, MG = mature grassland. The different colors showed in the figure represent the percentage of each functional group in the total aboveground biomass.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Response of the percentage of aboveground biomass of different functional groups to the nitrogen addition. AF = abandoned farmland, ED = extremely degraded grassland, SD = severely degraded grassland, MD = moderately degraded grassland, MG = mature grassland. The different colors showed in the figure represent the percentage of each functional group in the total aboveground biomass.
Mentions: The biomass of the grass group showed a significantly greater increase with nitrogen addition than that of other functional groups. Although the aboveground biomass of sedges and legumes changed during the three years (Table S1), this change had little influence on the total biomass because of their low proportion (Fig. 2). The grass group showed positive slopes, while the other groups showed negative or non-significant slopes (Table S2). The trend in the grass group was similar to that of the total biomass, which was more obvious in the degraded grassland than in the mature grassland. In AF, ED and SD, after a year of nitrogen addition the dominance of the grass group was enhanced. In the third year, this phenomenon also occurred in MD. However, MG showed the opposite trend. Nevertheless, the biomass of grass in all fields during all years increased with increasing N-treatment. In contrast, the biomass of legumes decreased significantly and the biomass of sedges and forbs showed no clear trend (Fig. 3, Table S2).

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.