Warming changes plant competitive hierarchy in a temperate steppe in northern China

Aims Quantifying changes in plant growth and interspecific interactions, both of which can alter dominance of plant species, will facilitate explanation and projection of the shifts in species composition and community structure in terrestrial biomes expected under global warming. We used an experimental warming treatment to examine the potential influence of global warming on plant growth and inter-specific interactions in a temperate steppe in northern China. Materials and methods Six dominant plant species were grown in monoculture and all 15 two-species mixtures for one growing season under ambient and elevated temperatures in the field. Temperature was manipulated with infrared radiators. Important findings Total biomass of all the six plant species was increased by 34-63% in monocultures and 20-76% in mixtures. The magnitude of the warming effect on biomass was modified by plant interactions. Experimental warming changed the hierarchies of both competitive response and competitive effect. The competitive ability (in terms of response and effect) on one C-4 grass (Pennisetum contrasiaticum) was suppressed, while the competitive abilities of one C-4 forb (Artemisia capillaris) and one C-3 grass (Stipa krylovii) were enhanced by experimental warming. The demonstrated alterations in growth and plant interactions may lead to changes in community structure and biodiversity in the temperate steppe in a warmer world in the future.