Spatial scaling of soil salinity indices along a temporal coastal reclamation area transect in China using wavelet analysis

ABSTRACT

High spatial variability of soil salinity in coastal reclamation regions makes it difficult to obtain accurate scale-dependent information. The objectives of this study were to describe the spatial patterns of saline-sodic soil properties (using soil pH, electrical conductivity (EC_1:5) and sodium ion content (SIC) as indicators) and to gain knowledge of the scaling relationships between those variables. The soil pH, EC_1:5 and SIC data were measured at intervals of 285 m along a 13,965-m temporal transect in a coastal region of China. The spatial variability of soil pH was weak but it was strong for soil EC_1:5 and SIC at the measurement scale. There was a significant positive correlation between soil EC_1:5 and SIC, while correlations between soil pH and either EC_1:5 or SIC were weak and negative. For each saline-sodic soil parameter, the variability changed with the decomposition scales. The high-variance area at the larger scales (≥570 m) occupied less than 10% of the total area in the local wavelet spectrum, which meant that the spatial variations of the salinity indicators were insignificant at these scales. For local wavelet coherency, at a scale of 1500–2800 m and a sampling distance of 0–4500 m, the covariance was statistically significant between any two of the saline-sodic soil parameters.

KEYWORDS:

• Saline-sodic soil
• spatial variation
• wavelet analysis
• scaling

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary Material

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Additional information

Funding

This work was supported by the National Nature Science Foundation of China through grants no. 41471180, the Open Funding Project (no. JXSB201304) of Jiangxi Provincial Key Laboratory of Soil Erosion and Prevention (Jiangxi Institute of Soil and Water Conservation), the Excellent Creative Talents Support Program of Hohai University, and by the Fundamental Research Funds for the Central Universities (2015B14814), and by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).