Identifying localized and scale-specific multivariate controls of soil organic matter variations using multiple...

Area of Science:

• Environmental Science
• Soil Science
• Geospatial Analysis

Background:

• Soil organic matter (SOM) distribution is influenced by environmental factors at various scales.
• Previous research often focused on individual factors, neglecting their combined effects on SOM.
• Understanding multivariate controls is crucial for accurate soil mapping and environmental management.

Purpose of the Study:

• To compare univariate and multivariate environmental factor controls on SOM distribution along two transects in China.
• To assess the localized and scale-dependent relationships between SOM and environmental variables.
• To identify dominant individual and combined environmental factors influencing SOM variations.

Main Methods:

• Calculated bivariate wavelet coherence (BWC) for SOM and individual factors.
• Employed multiple wavelet coherence (MWC) to analyze combinations of factors controlling SOM.
• Utilized Average Wavelet Coherence (AWC) and Percent Area of Significant Coherence (PASC) to quantify factor dominance.

Main Results:

• Mean annual temperature (MAT) was the dominant factor for SOM along the NE transect (AWC=0.39, PASC=16.23%).
• Topographic wetness index (TWI) dominated SOM variations along the N transect (AWC=0.39, PASC=20.80%).
• MWC revealed synergistic effects: Slope, NPP, and MAP (NE transect; AWC=0.91, PASC=58.03%) and TWI, NPP, NDVI (N transect; AWC=0.83, PASC=32.68%) were highly influential combinations.

Conclusions:

• Multiple wavelet coherence (MWC) effectively identifies combined environmental factor controls on SOM variations.
• Multivariate analysis provides a more comprehensive understanding of SOM dynamics at larger spatial scales.
• Findings can enhance digital soil mapping accuracy and landscape-level soil management strategies.