Variation in glomalin in soil profiles and its association with climatic conditions, shelterbelt characteristics, and soil properties in poplar shelterbelts of Northeast China

Glomalin-related soil protein (GRSP) sequesters large amounts of carbon and plays important roles in maintaining terrestrial soil ecosystem functions and ecological restoration; however, little is known about GRSP variation in 1-m soil profiles and its association with stand characteristics, soil properties, and climatic conditions, hindering GRSP-related degraded soil improvement and GRSP evaluation. In this study, we sampled soils from 1-m profiles from poplar ( Populus spp.) shelterbelts in Northeast China. GRSP contents were 1.8–2.0 times higher in the upper 40 cm soil layers than at 40–100 cm. GRSP-related soil organic carbon (SOC) sequestration in deeper soil layers was ~ 1.2 times higher than in surface layers. The amounts of GRSP-related nutrients were similar throughout the soil profile. A redundancy analysis showed that in both surface and deeper layers, soil properties (pH, electrical conductivity, water, SOC, and soil nutrients) explained the majority of the GRSP variation (59.5–84.2%); the second-most-important factor in GRSP regulation was climatic conditions (temperature, precipitation, and altitude), while specific shelterbelt characteristics had negligible effects (