Effect of the competition mechanism of between co-dominant species on the ecological characteristics of Populus euphratica under a water gradient in a desert oasis

Abstract

The relationship between the growth characteristics of vegetation and factors that limit the protection of relevant populations and communities needs to be clarified. To gain a deeper understanding of the mechanism that couples groundwater factors with the growth of Populus euphratica in a desert ecosystem, as well as to explore the effect of its competitive relationship with Tamarix chinensis under the restrictive conditions of self-development and community succession, we established 11 typical sample plots in the Daliyaboyi Oasis in the Taklimakan Desert. In the current study, we evaluated the competitive relationship between these two dominant species under a groundwater gradient to illustrate the effect of the competition between groundwater factors and restrictive conditions on the plasticity of the ecological characteristics of P. euphratica via redundancy analysis. The results showed that groundwater depth and pH were the main variables that controlled growth and development of P. euphratica. Spatial heterogeneity of the water environment caused changes in the morphological and physiological characteristics of P. euphratica. Groundwater factors induced competition between P. euphratica and T. chinensis. Such a stress relationship prompts P. euphratica to reduce its own population density as well as photosynthetic and metabolic rates to ensure its survival and remain as a dominant species. Our results support the hypothesis that competition does not produce a single elimination effect and that complex symbiotic mechanisms may reduce the severity of low-density population competition to ensure the coexistence of species.

Keywords

• Species coexistence
• Groundwater factors
• Groundwater depth
• Competition mechanism