Abstract
Biological soil crusts (BSCs) can improve the stability and health of native plant communities in arid ecosystems. However, it is unknown whether BSCs can also inhibit invasions of exotic vascular plants on stabilized reclaimed sand dunes. To answer this question, we conducted a greenhouse experiment to test the effects of cyanobacteria-dominated BSCs on 1) seed germination and biomass of an exotic grass (Stipa glareosa P. Smirn.), and 2) individual biomass of the exotic S. glareosa growing with two native plants, Eragrostis poaeoides Beauv. and Artemisia capillaris Thunb. Our experiment included three BSC treatments (intact crust, disturbed crust, and bare soil) and five species trials (native E. poaeoides alone, E. poaeoides mixed with exotic S. glareosa, native A. capillaris alone, A. capillaris mixed with exotic S. glareosa, and S. glareosa alone). The results showed that cyanobacteria-dominated crusts can significantly reduce the cumulative percent germination of the exotic grass (P<0.001) and native plants (P<0.001). Maximum cumulative percent germinations of the exotic grass and two native plants were found in bare soil, and minimum in intact crusts. The interaction of crust treatment × species trials on shoot biomass of the two native plants was significant (P<0.05). These results indicate that the presence of BSCs on stabilized sand dunes may reduce the germination of the exotic and two native plants. The effect of reducing exotic and native plant seeds germination would maintain more diverse plant communities and contribute to the formation of clumped vegetation patterns. We conclude that BSCs act as a natural regulator for vegetation patterns and thus promote ecosystem stability and sustainability.
Highlights
Drylands, areas with a severe and fragile ecological environment, cover more than one third of the terrestrial land surface [1,2]
Results of the multiple comparison suggested that seed cumulative percent germination of A. capillaris was significantly different in bare soil than in the two crust treatments, but there were no significant differences between disturbed and intact crust treatments (P = 0.152)
The results showed that the shoot biomass of the two native plants markedly decreased when they were mixed with the exotic grass compared to their growth monoculture, except for A. capillaris in bare soil (Fig 3)
Summary
Areas with a severe and fragile ecological environment, cover more than one third of the terrestrial land surface [1,2]. Drylands are characterized by a sparse presence of vascular plants due to low water availability, and low rates of nutrient turnover or a limited ability to acquire resources due to extreme temperatures [3,4]. The soil surface in drylands is often. BSCs create a boundary for most dissolved inputs and losses from soils [5]. They influence soil water distribution by affecting rainfall infiltration [13,14], decreasing soil evaporation [15,16,17], and absorbing condensation moisture [18,19]. BSCs may improve the stability of soil [20,21] via their ability to withstand erosion [22], and fix carbon and nitrogen [23,24,25]
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