Chin J Plant Ecol ›› 2009, Vol. 33 ›› Issue (1): 97-107.DOI: 10.3773/j.issn.1005-264x.2009.01.011

• Research Articles • Previous Articles     Next Articles

BIOMASS REPRODUCTIVE ALLOCATION AT DIFFERENT ORGANIZATIONAL LEVELS OF THREE STIPA SPECIES IN INNER MONGOLIA GRASSLAND OF CHINA

TIAN Da-Shuan1, BAO Xiang2, GUAN Qi-Ge3, PAN Qing-Min1,*()   

  1. 1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    2Grassland Station of Xilingol Union, Inner Mongolia Autonomous Region, Xilinhot, Inner Mongolia 026000, China
    3Grassland Station of Abaga Banner, Inner Mongolia Autonomous Region, Abaga, Inner Mongolia 011400, China
  • Received:2008-03-31 Accepted:2008-07-23 Online:2008-03-31 Published:2009-01-30
  • Contact: PAN Qing-Min

Abstract:

Aims Resource allocation plays a central role in linking life history evolution and functional plant ecology. Stipa species are widely distributed in the Inner Mongolia grassland of China; however, their resource allocation patterns are not well addressed. We selected three Stipa species, S. krylovii, S. grandis and S. baicalensis and examined their reproductive allocation patterns at four organizational levels. We focused on two specific questions: 1) do these Stipa species exhibit similar or different reproductive allocation patterns at the same organizational level and 2) which step of biomass reproductive allocation is limiting the plant performance of each species?
Methods We conducted this experiment in three sites dominated by S. krylovii, S. grandis and S. baicalensis, respectively, in Inner Mongolia grassland in 2007. At each site we investigated the density, height and biomass of reproductive tillers and vegetative tillers of each species in ten quadrats (1 m×1 m). We randomly sampled 50 reproductive tillers of each species and analyzed reproductive allocation at different organizational levels.
Important findings Three Stipa species exhibited significant divergence in reproductive allocations at different organizational levels. At the bunch level, S. krylovii and S. grandis allocated more biomass to reproductive tillers than S. baicalensis. At the reproductive tiller level, S. krylovii allocated less biomass to reproductive tillers than S. grandis and S. baicalensis. At the spike level, S. grandis and S. krylovii allocated about 60% and 50% biomass to diaspore, respectively, while S. baicalensis allocated about 40% biomass to diaspores. At the diaspore level, S. grandis and S. krylovii allocated about 70% and S. baicalensis allocated about 90% biomass to fertilized diaspores. Despite these differences, the fraction of fertilized diaspore biomass in bunch biomass exhibited convergence. The species had different bottlenecks in reproductive allocation. Stipa grandis and S. krylovii were limited by the allocation of biomass from reproductive tillers to spikes, while S. baicalensis was limited by the allocation of biomass from bunch to reproductive tiller or by the allocation from spike to diaspores. Our experiment suggests these species have developed different life history strategies.

Key words: sexual reproduction, resource allocation, bunchgrass, diaspore, divergence, convergence