Afforestation programs are a mitigation option for land degradation and ongoing climate change. Increasing soil organic carbon (SOC) concentration is a desirable aspect of afforestation. The selection of arbuscular mycorrhizal fungi symbiotic plants can help us establish the forest cover during afforestation.

Glomalin (operationally defined as glomalin-related soil protein; GRSP) is considered a ubiquitous component of soil protein. Knowing whether glomalin-related root protein concentration can influence glomalin-related soil protein and soil organic carbon pool in tree proximities would have a great significance when managing an afforestation program.

In a study published in Land Degradation & Development, researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences provided evidence that glomalin-related root protein concentration in roots varies with tree species owing to differences in root arbuscular mycorrhizal fungi colonization intensity.

The researchers assessed the glomalin in different tree roots (i.e., glomalin-related root protein; GRRP) and its influence on GRSP and SOC storage in trees’ rhizosphere and interspace.

They selected six native tree species sites (Hardwickia binata, Lagerstroemia parviflor, Diospyros melanoxylon, Terminalia tomentosa, Shorea robusta, and Anogeissus latifolia), and a teak (Tectona grandis) plantation site in central India.

They found that the root arbuscular mycorrhizal fungi colonization intensity and glomalin-related root protein differed among trees, with the higher values appearing in all native or forest trees compared with teak plantation.

Moreover, glomalin-related root protein concentration mediated soil organic carbon storage in tree proximities (rhizosphere and interspace) by influencing the soil's glomalin-related soil protein concentration.

The regression analysis confirmed that glomalin-related root protein was a strong predictor of glomalin-related soil protein (for both rhizosphere and interspace); however, glomalin-related soil protein had strongly predicted soil organic carbon.

"We therefore recommend that reforestation with trees that produce higher glomalin-related root protein can be advantageous to achieve greater glomalin-related soil protein and soil organic carbon storage on degraded land," said Ashutosh Kumar Singh, an Indian postdoc studying at XTBG.