Soil characteristics and ecological thresholds of Suaeda salsa wetlands

Figures & data

Figure 1. Location of the study area.

Figure 2. Changes in soil water content in different degraded areas.

The letters a, b, c, and d indicate significant differences between the different degraded areas for the same soil depth (P < 0.05), while A, B, C, and D represent significant differences between different soil layers in the same degraded area (P < 0.05).

Figure 3. Particle size distribution in the different degraded areas.

Figure 4. Soil total salt content in the different degradation areas.

Letters a, b, c, and d indicate significant differences between the different degraded areas for the same soil depth (P < 0.05), while A, B, C, and D represent significant differences between different soil layers in the same degraded area (P < 0.05).

Figure 5. Soil salt ion concentration in different degraded areas.

Letters a, b, c, and d indicate significant differences between the different degraded areas for the same soil depth (P < 0.05), while A, B, C, and D represent significant differences between different soil layers in the same degraded area (P < 0.05).

Figure 6. Soil pH in different degraded areas.

Letters a and b indicate significant differences between different degraded areas at the same soil depth (P < 0.05), while A and B represent significant differences between different soil layers in the same degraded area (P < 0.05).

Figure 7. Changes in available soil nutrient concentration in different degraded areas.

Letters a, b, c, and d indicate significant differences between different degraded areas at the same soil depth (P < 0.05), while A and B represent significant differences between different soil layers in the same degraded area (P < 0.05).

Figure 8. Soil organic matter content in the different degradation areas.

Letters a, b, c, d, and e indicate significant differences between different degraded areas at the same soil depth (P < 0.05), while A and B represent significant differences between different soil layers in the same degraded area (P < 0.05).

Table 1. Correlation analysis of plant properties of Suaeda salsa.

Properties	Weight per plant	Density	Biomass
Weight per plant	1
Density	0.521**	1
Biomass	0.644**	0.870**	1

* indicates a significant correlation at P < 0.05.

** indicates a significant correlation at P < 0.01.

Table 2. Correlation between Suaeda salsa biomass and soil physicochemical properties.

x	y	Fitted curve equation	R^2	P
Naturallogarithm of biomass	Total salt content	y = −0.022x^2 + 0.5211x + 3.4056	0.402	P < 0.05
	Water content	y = −23.451x^2 + 22.736x + 1.1439	0.598	P < 0.05
	K^+	y = −0.0019x^2 + 0.1044x + 4.9639	0.089	P > 0.05
	Na^2+	y = −2E-06x^2 + 0.0028x + 5.3733	0.114	P > 0.05
	Mg^2+	y = −0.0051x^2 + 0.2197x + 4.1129	0.171	P > 0.05
	Ca^2+	y = −5E-05x^2 + 0.0091x + 6.0347	0.183	P > 0.05
	Sand	y = 0.0042x^2 – 0.1133x + 6.8594	0.062	P > 0.05
	Silt	y = 0.0003x^2 – 0.0595x + 8.9336	0.032	P > 0.05
	Clay	y = 0.0013x^2 – 0.0369x + 6.3943	0.017	P > 0.05
	pH	y = −0.0783x^2 + 0.6716x + 6.202	0.080	P > 0.05
	Alkaline nitrogen	y = 0.0005x^2 – 0.0351x + 6.6323	0.029	P > 0.05
	Availablephosphorus	y = 0.0004x^2 – 0.0278x + 6.4987	0.024	P > 0.05
	Available potassium	y = 2E-06x^2 – 0.0024x + 6.5602	0.056	P > 0.05
	Organic matter	y = 0.006x^2 – 0.1056x + 6.4972	0.072	P > 0.05

Figure 9. Quadratic curve fitting of Suaeda salsa biomass with soil water content and total salt content.