Population dynamics of Artemisia scoparia in heterogeneous habitats in the desert steppe

Abstract

To understand the intra- and inter-annual population dynamics of Artemisia scoparia in the desert steppe, we set up three treatments, i.e., increasing the precipitation by 30%, reducing the precipitation by 30%, and the control (CK) in each soil habitat of aeolian sandy soil, sierozem soil, and bedrock weathered sedimentary soil. We drew up the dynamic life table to produce population survival and death curves and analyzed the population dynamics of A. scoparia in different habitats. Results showed that the survival curve of A. scoparia was approached to Deevey-1type. The survival rate was high in the early growth stage and tended to be relatively stable. The mortality rate maintained at a low level, but rose fast at the end of the growth stage. The individual survival number of A. scoparia in all habitats fluctuated at the early stage and declined at the later stage. The mortality rates of A. scoparia in habitats of both aeolian sandy soil and sierozem soil fluctuated greatly. There was no significant difference in the effects of increased and decreased precipitation treatments on the mortality rate of A. scoparia. Soil types had significant effects on all parameters, including the plant height, crown width, density, cover, and biomass of A. scoparia. Precipitation treatments had significant impacts on plant height, crown width and coverage of A. scoparia, and had no significant effect on plant density and biomass. The interactions between soil type and precipitation treatments had only a significant impact on plant height and crown width. The plasticity index of biomass in the habitat of bedrock weathered sedimentary soil was significantly higher than that in habitats of aeolian sandy soil and sierozem soil, while the plasticity index of plant coverage in the habitats of both sierozem soil and bedrock weathered sedimentary soil were significantly higher than that in the habitat of aeolian sandy soil. The density plasticity index of increased precipitation treatment was significantly higher than those of CK and the decreased precipitation treatments. The plasticity index of plant height and crown width were higher than other parameters, indicating that A. scoparia could respond to habitat changes by giving priority to these two parameters under different habitat pressures.