Often, the dominant image of natural carbon sequestration is a vast forest canopy, but while reforestation is vital, it is not the most stable long-term carbon sink. Carbon stored in trees is vulnerable: wildfires release carbon as CO₂, and storms cause fallen trees to decompose, feeding microbes that respire carbon back into the atmosphere. To build resilient carbon sequestration systems, we must expand our focus to other ecosystems—such as grasslands sustained by herd animals.
The Role of Herd Animals in Grassland Ecosystems
Restoring and expanding grasslands means dedicating more land to herd animals like bison (North America), wildebeest and antelope (African savannas), reindeer and caribou (Arctic tundra), and elephants (Africa and parts of Asia). Trophic rewilding reestablishes the intricate food webs that sustain these ecosystems. Through grazing, trampling, and nutrient cycling, herd animals regenerate grasslands, making them powerful carbon sinks.
Unlike forests, where carbon is stored in above-ground biomass, grasslands primarily store carbon underground. Their deep-rooted perennial grasses sequester carbon in subsoil and humus, a highly stable form of organic matter that can last centuries or millennia. While tree roots also store carbon, they eventually decompose upon deforestation, releasing CO₂. Conversely, grasslands continuously build soil carbon through root growth and turnover, making them a more enduring carbon sink.
How grazing enhances soil carbon storage
Grazing by herd animals facilitates long-term carbon storage in several ways:
Increased Root Turnover – When grasses are grazed, they shed fine roots, which decay and contribute to humus formation, locking carbon into the soil.
Boosted Microbial and Fungal Activity – Manure, dead roots, and trampled plant material provide organic inputs that fuel microbes, which convert carbon into stable soil compounds.
Stabilized Carbon in Soil Aggregates – Organic matter binds with soil minerals, forming stable aggregates that slow decomposition and protect stored carbon from being released.
