The threat of climate change is growing each year. With global temperatures rising, sea levels are knocking on our coastal doors. Carbon emissions, totalling 40 million metric tonnes annually, are a major contributor to this temperature rise. Governments worldwide are implementing measures to reduce carbon emissions by transitioning to clean energy sources. Another method to decrease carbon in the atmosphere is by enhancing its absorption into our environment. 

Planting trees helps with carbon sequestration by removing carbon dioxide from the environment and storing it as biomass. However, trees can struggle to survive in low-rainfall regions. With this in mind, the Maharashtra Forest Department (MFD) decided to plant grasses instead of trees in the dry areas of Solapur District.

The question that emerged was whether these grasses are successful at capturing carbon. To explore this issue, MFD collaborated with researchers from the Ashoka Trust for Research in Ecology and the Environment (ATREE) to study the effects of ecological restoration with native grass plantations on soil carbon.

Under the Compensatory Afforestation Fund Management and Planning Authority (CAMPA) Act of 2016, the MFD has been planting indigenous grass species like Dichanthium annulatum, Chrysopogan fulvus, and Cenchrus setigerus since 2019 in the Malshiras Range of the Solapur Forest Division. 

Researchers aimed to investigate the impact of a three-year ecological restoration with native grasses on soil carbon densities. Traditionally, this involves collecting soil samples annually to track changes over time. However, the researchers opted for an alternative method called space-for-time substitution. This approach involves collecting soil samples from sites that have undergone restoration for one, two, and three years. Additionally, soil samples were gathered from control sites with no restoration and from two reference sites where native grasses have naturally thrived for a long period of time. Manan Bhan, Fellow in Residence at ATREE and lead author of the study, says, 

We need two things when measuring carbon stored in soil: soil organic carbon (SOC), which is the percentage of carbon in the soil, and bulk density, which is the density of the soil. 

To measure SOC and bulk density, researchers obtained soil samples by digging up to 30 cm deep. SOC was estimated using combustion gas chromatography, while bulk density was determined by the soil’s mass per unit volume. Using these values, researchers calculated the average SOC value per hectare, which will be compared across treatment and control sites.

“We found that restoration had a positive effect on soil carbon sequestration, with nearly a 50% increase in carbon after three years compared to the control sites,” says Abi Vanak, Senior Fellow, Director of the Centre for Policy Design, and second author of the study. The results show that soil carbon sequestration increases over time. The oldest plantations, aged three years, showed the highest increase in SOC at 53%, followed by two-year plantations at 28%, and one-year plantations at 23%.

“Restoration efforts that focus on planting indigenous grasses not only enhance carbon sequestration but also support local biodiversity. This dual benefit can be extended to other grasslands, promoting ecological integrity and resilience,” says P. C. Nath, a research associate at the Mobius Foundation, a sustainability think tank based in Delhi.

Highlighting the study’s importance, Vanak adds,

Our study also examines the cost of carbon sequestration by comparing below-ground carbon sequestration by grass plantations in soil to above-ground carbon sequestration in trees. Planting trees can be costly, as it requires transporting water to these semi-arid and dry areas.