Chin J Plan Ecolo ›› 2016, Vol. 40 ›› Issue (10): 980-990.DOI: 10.17521/cjpe.2016.0141

• Research Articles • Previous Articles     Next Articles

Influence of nitrogen addition on the primary production in Nei Mongol degraded grassland

Jing WANG1,2, Shan-Shan WANG1,2, Xian-Guo QIAO1,2, Ang LI1, Jian-Guo XUE1, Muqier HASI1,2, Xue-Yao ZHANG1,2, Jian-Hui HUANG1,*   

  1. 1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China

    2College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
  • Online:2016-10-10 Published:2016-11-02
  • Contact: Jian-Hui HUANG


Aims Irrational utilization and global climate change have caused degradation of grassland ecosystems in northern China with low soil fertility, decreased vegetation coverage and productivity. Nitrogen addition has been suggested an effective way to enhance restoration of those degraded grasslands. In this study, we selected a typical steppe with three different degrading levels, including lightly, moderately and heavily degraded communities, in East Ujimqin, Nei Mongol. Our objectives of this study are to examine if and how nitrogen (N) addition can enhance restoration of those degraded grasslands Methods Treatments with four levels of N addition (0, 5.0, 10.0 and 20.0 g N·m-2·a-1) were conducted to each of the three degraded communities from 2014 to 2015. Nitrogen was applied as urea in June of both years. Aboveground biomass was collected at the species level in 1 m × 1 m plot in August each year, all species biomass was summed as net primary production, and biomass of plant functional groups was calculated by perennial rhizome grasses, perennial bunchgrasses, perennial forbs, shrubs and semi-shrubs, annuals and biennials.Important findings Our results showed that the high (20.0 g N·m-2·a-1) and medium level N addition (10.0 g N·m-2·a-1) significantly increased the aboveground biomass of the slightly degraded community by 53.1% and 51.6% compared with no N addition. N addition had no significant effects on the moderately and heavily degraded communities. N addition with high and medium levels increased aboveground biomass of perennial rhizome grasses by 45.1% and 47.7%, but decreased that of perennial forbs by 37.4% and 42.1% at the slightly degraded community. Our results indicated that N addition could increase the growth of perennial rhizome grasses, and the growth of perennial forbs was suppressed consequently. Our results suggest that even the application of N fertilizers can only be helpful to restoration of those slightly degraded grasslands. Besides, N addition had no significant effects on species richness in different degraded communities indicating the fact that the study may not last long enough. For the purpose of increasing aboveground biomass of degraded grassland, we should not only consider the type and quantity of fertilization, but also the attribute of the degraded communities. In addition, the response of degraded community in biomass may strongly be impacted by degrading level of studied grassland.

Key words: degraded grassland, nitrogen addition, aboveground biomass, plant functional group, species richness