Growth Dynamic of Tamarix chinensis Plantations in High Salinity Coastal Land and Its Ecological Effect

Abstract

Tamarisk (Tamarix chinensis), a pioneer native halophyte from the coastal region of North China, has a high potential to establish in high salinity soil. The ecological benefits from planting tamarisk include changes to the structure and function of the saline land ecosystem. However, field experiments on the ecological benefit of using tamarisk in the restoration of saline lands along the coastal areas of China are lacking. In the current study, tamarisk was planted in 2005, 2007, and 2009 to assess the effectiveness of the plant in vegetation and saline soil restoration. The individual biomass, carbon sequestration, species diversity, and soil characteristics of tamarisk plantations in the different planting years were investigated. The results showed that tamarisk grew well with increasing individual biomass during the experimentation period. Carbon density increased from 0.98 t(C) hm⁻² (land without tamarisk) to 4.78 t(C) hm⁻² in the 3-year plots, 5.56 t(C) hm⁻² in the 5-year plots, and 6.89 t(C) hm⁻² in the 7-year plots. Significant soil quality improvement was indicated by lower soil salinity and higher organic matter. Salt content in the 0- to 10-cm soil layer of barren land was 10.53 g kg⁻¹, while it was only 3.35 g kg⁻¹, 1.86 g kg⁻¹, and 5.54 g kg⁻¹ in the 3-, 5-, and 7-year plots with tamarisk, respectively. Potassium (K) availability in the soil was increased. In addition, tamarisk played a significant “eco-engine” role in terms of increasing the species of surrounding grasses. Where only 8 grass species existed in this area before tamarisk planting, a total of 15 grass species existed in the 7-year plot. However, the importance value of salt-tolerant species decreased in tamarisk plots. Clonal plants such as Aeluropus sinensis and Sonchus arvensis became more dominant than seed propagation plants such as Suaeda salsa. This suggested that tamarisk plants progressively alleviated salt stress in the coastal environment. The study demonstrated that tamarisk was effective in vegetation regeneration in saline lands, improving soil quality and increasing carbon sequestration.