Chin J Plant Ecol ›› 2009, Vol. 33 ›› Issue (6): 1065-1074.DOI: 10.3773/j.issn.1005-264x.2009.06.006

• Original article • Previous Articles     Next Articles

EFFECTS OF GRAZING ON FOLIAGE BIOMASS ALLOCATION OF GRASSLAND COMMUNITIES IN XILIN RIVER BASIN, INNER MONGOLIA

REN Hai-Yan, ZHENG Shu-Xia, BAI Yong-Fei()   

  1. State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • Received:2009-01-01 Accepted:2009-04-27 Online:2009-01-01 Published:2021-04-29
  • Contact: BAI Yong-Fei

Abstract:

Aims Our objective is to determine whether 1) characteristics of gazing-induced individual miniaturization differ among plant species and across grassland communities, 2) miniaturized plants have detectable changes in resource allocation, and 3) grazing-induced changes in plant resource allocation affect ecosystem functioning at the plant community level.
Methods Resource allocation of 144 common species from grassland communities, i.e. Carex appendiculata meadow,Stipa baicalensis meadow steppe,Leymus chinensis typical steppe,Stipa grandis typical steppe, Caragana microphylla typical steppe, and Artemisia frigida typical steppe, were investigated along a soil moisture gradient in the Xilin River Basin, Inner Mongolia. We measured morphological traits, including reproductive height, vegetative height, canopy coverage, leaf biomass, stem biomass, stem:leaf ratio, and total biomass of common species at the individual and community levels from paired ungrazed and grazed plots.
Important findings Long-term grazing across the six grassland communities significantly decreased average plant morphological traits such as reproductive height, vegetative height, canopy coverage, leaf biomass, stem biomass, stem:leaf ratio, and total individual biomass in 55%-94% of the common plant species, indicating that individuals tend to miniaturize in response to overgrazing. At the community level, grazing also decreased stem, leaf, and total aboveground biomass. Plant species increased their biomass allocation to leaves, but decreased biomass allocation to stems in grazed plots as compared to the ungrazed plots. This suggests that the increase in resource allocation to photosynthetic organs (e.g., leaves) is likely an important strategy of plants adapting to long-term grazing. In contrast, light grazing increased plant biomass production at both individual and community levels at the meadow steppe. In addition, soil moisture may have important effects on plant resource allocation, with high biomass allocation to stems in wet habitats.

Key words: grazing, morphological traits, individual miniaturization, stem:leaf ratio, resource allocation