Hawaii relies on agroforestry to meet their 2045 climate goals

A group of researchers quantified the potential of agroforestry systems on islands. The suitable area is large. Sequestration reaches 125 tons per hectare. A value similar to that of native forests

by Matteo Cavallito

 

In Hawaii, converting unused agricultural land to agroforestry areas with the goal of increasing carbon storage capacity maximizes benefits for local communities. That is the conclusion of a study conducted by a team of researchers from the local University of Mānoa, Kamehameha Schools-a local private school system-and the Institute of Pacific Islands Forestry.

The authors conducted interviews with agroforestry system operators and analyzed available literature on the topic, assessing the effects of these practices in different rainfall zones and on different soil types on the islands.

The benefits of agroforestry

Agroforestry is a strategy that combines the protection of native trees and other plants with agricultural crops. To date, explains research published in the journal Scientific Reports, “Indigenous and other place-based multi-strata agroforestry systems are important conservation and agricultural strategies. Yet their ecosystem services, including carbon sequestration benefits, have received little research attention.”

To explore these issues further, the researchers examined the possibility of transforming abandoned agricultural lands into these types of cropping systems.

This approach, they explain in a statement released by the University of Hawaii Mānoa, could also help reduce the risks of extreme wildfires caused by agricultural land abandonment, But also increase local food production and revitalize native land management practices. Finally supporting the islands’ goal of carbon neutrality by 2045.

More than 1,500 square kilometers of available soil

Through the interviews conducted and analytical models employed, the authors were able to outline future scenarios on areas transformed into multi-layer agroforestry, as well as quantify potential benefits and in terms of carbon sequestration. The study then found that more than 1,500 sq. km of unmanaged agricultural land would still be suitable for agroforestry under current climate conditions. This is “about half of unmanaged fallow agricultural lands.”

Moreover, a significant portion of this land, 1,200 sq. km, “remained suitable under a dry climate change scenario.”

Finally, storage models showed that restored agroforestry systems could store between 92 and 125 tons of carbon per hectare in aboveground vegetation alone. This is, on balance, comparable to that of native forests.

 

42 million tons less CO2

The study thus highlights the potential of lands potentially restorable by agroforestry (mainly non-native grasslands and shrublands but also agricultural lands) in carbon sequestration. A consequence of soil regeneration. “Considering both above-ground and soil carbon, overall carbon benefits are expected across over a third of the potential restoration area with just 5% of the area with expected overall losses,” the research explains.

“With potential carbon sequestration similar to or greater than that of native forest restoration, restoration through agroforestry represents an important pathway to achieving carbon benefits.”

Specifically, according to the study, a complete transition of land to an agroforestry system would reduce emissions by about 42 million tons of CO2 in 30 years, which is equivalent to the impact of 100 million barrels of oil, or about two years of total consumption in the state of Hawaii.