Strong scale-dependent relationships between fine-root function and soil properties uncovered with spatially coupled...

Area of Science:

• Ecology
• Plant Biology
• Soil Science

Background:

• Fine-root trait variation often occurs at fine spatial scales but is infrequently linked to soil (edaphic) properties.
• Understanding the interplay between root traits and soil conditions is vital for forest ecosystem functioning.

Purpose of the Study:

• To investigate the spatial scales of variation in fine-root traits and soil properties.
• To identify the edaphic drivers influencing fine-root function in Handroanthus ochraceus.
• To explore relationships among various fine-root traits.

Main Methods:

• A nested sampling scheme was employed across multiple spatial scales (within trees, among trees, and across sites).
• Fine-root samples were analyzed for physiological, symbiotic, morphological, chemical, and architectural traits.
• Paired soil physical and chemical properties were quantified.

Main Results:

• Both fine-root traits and soil properties exhibited significant variation, often most pronounced at fine spatial scales.
• Root arbuscular mycorrhizal colonization and phosphomonoesterase activity were linked and influenced by coarse-scale soil heterogeneity (bulk density, magnesium, phosphate).
• A trade-off between root diameter and specific root length, respiration, and nitrogen concentration was driven by fine-scale ammonium heterogeneity.

Conclusions:

• Intraspecific fine-root trait responses to soil properties can manifest across multiple spatial scales simultaneously.
• Accurate spatial matching of root and soil variation is essential for detecting these responses.
• Base cations played a more significant role than nitrogen and phosphorus in influencing fine-root traits.