Chin J Plan Ecolo ›› 2018, Vol. 42 ›› Issue (4): 430-441.DOI: 10.17521/cjpe.2017.0135

• Research Articles • Previous Articles     Next Articles

Effects of nitrogen addition on the plant diversity and biomass of degraded grasslands of Nei Mongol, China

Qian YANG1,2,Wei WANG2*(),Hui ZENG1,2*()   

  1. 1 Shenzhen Graduate School, Peking University, Shenzhen, Guangdong 518055, China
    2 College of Urban and Environment, Peking University, Beijing 100871, China
  • Online:2018-04-20 Published:2018-03-21

Abstract:

Aims Anthropogenic disturbances and climate change have resulted in large scale degradation of grasslands across the landscapes in Nei Mongol. Fertilization, especially with nitrogen (N) addition, has been proposed and applied as an important management practice to promote primary production for these degraded grasslands. In this study, we examined the changes in plant diversity and biomass at three levels of degradations with N addition.

Methods Nitrogen addition experiment was installed in 2011. Six levels of N addition (0, 10, 20, 30, 40, and 50 g·m -2·a -1) were conducted at grasslands with three levels of degradations. Nitrogen was added at the beginning of each month from May to August each year. We investigated the changes in plant species richness and aboveground biomass by species in August, 2016. The total biomass of the community, as well as the biomass of each plant functional group (grasses and forbs) was calculated based on species composition.

Important findings We found that: (1) N addition decreased species richness and diversity at communities under moderate and severe degradations, but insignificant under extreme degradation. (2) N addition increased the aboveground biomass at communities under three levels of degradations. (3) N addition increased the aboveground biomass of the grasses and its proportion to the total biomass, but not on the total biomass of the forbs although it also decreased the proportion of aboveground biomass. These results indicate that the impacts of N addition on ecosystem function depended on plant function type. In addition, the fertilization effects should are examined at community level and by the degree of the degradation.

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