Study materials
In this study, four abundant species in the Inner Mongolia Steppe were
used. S. grandis and S. krylovii were used as the target
species and as neighbor for each other. Both S. grandis andS. krylovii , two perennial tussock grasses, are the two of the
most widely distributed grasses and dominate the landscape of the vast
semi-arid area of the Inner Mongolia steppe, China. S. grandiswith a canopy height over 100cm is a superior competitor for light and
has lower tolerance to unfertile condition than S. krylovii , thusS. grandis occupies relatively moist and fertile typical
grassland while S. krylovii occupies dry and infertile habitats
(Chen et al. , 2013). The growth potential of S. kryloviishould be comparable to that of S. grandis because the
communities under seriously disturbance such as grazing, S.
krylovii would co-dominate the communities with S. grandis or
even dominate the communities by replacing the dominance of S.
grandis (Lu and Wu 1996).
Leymus chinensis and Agropyron cristatum were used as
neighbor species in this study. L. chinensis can be a dominant
species in the meadow grasslands, and usually co-dominates the typical
communities with S. grandis or S. krylovii in the Inner
Mongolia steppe, which indicated that the growth potential of L.
chinensis may be one of the highest in the Inner Mongolia Steppe and
the tolerance to low nutrition of L. chinensis should be
comparable to that of S. krylovii (Zhu, 2004). A.
cristatum is a companion species in non-degraded S. grandiscommunity and a subdominant species in moderate-grazed S. grandisor S. krylovii communities, suggesting that the growth potential
and the tolerance to low nutrition of A. cristatum are between
those of S. grandis and S. krylovii (Xu et al. 2015).
In a S. grandis - S. krylovii community in the middle of
Inner Mongolia Steppe (44°15’N, 116°23’E, 1132 m altitude), the seeds of
the four species were obtained and 5 ~20 cm soil was
collected and homogenized for the microcosm experiment. The soil was a
Calcic luvisol (FAO-UNESCO), with the pH of 7.35. The soil organic
matter, availability of N and P were 15.6 mg/g, 0.17 mg/kg, 4.72 mg/kg,
respectively.