Ecosystem engineers of the dry zone
In the semi-arid central dry zone of Myanmar, prominent dirt mounds built by fungus-farming termites, primarily of the genus Odontotermes, fundamentally alter the landscape. These termites are ecosystem engineers, meaning they physically modify their environment in ways that affect other organisms. The mounds, which can be several meters in diameter, are complex structures; they are complex structures and biogeochemical hotspots creating "islands of fertility" in an otherwise nutrient-poor environment.
The process begins underground. Worker termites forage for dead organic matter like wood and leaf litter, which they transport back to their subterranean nest. There, they cultivate a symbiotic fungus, Termitomyces, on a special comb-like structure made from their fecal matter and the gathered plant material. This fungus predigests the tough lignocellulose in the plant matter, making it digestible for the termites. As the termites build and maintain their mounds using saliva and feces, they concentrate nutrients scavenged from a wide surrounding area. This results in mound soil that is significantly enriched with essential plant nutrients. Studies show mound soils often have higher concentrations of phosphorus, potassium, calcium, and magnesium compared to the adjacent, unmodified soils. The physical structure of the mound also changes, typically showing a much higher clay content than the surrounding sandy or loamy soils.
Islands of life
The altered soil chemistry and physics of termite mounds have a direct impact on local plant life. The increased availability of nutrients like phosphorus and nitrogen, combined with better water retention from higher clay and organic matter content, creates a favorable microhabitat for plant growth. This leads to a visible pattern in the landscape: the mounds and their immediate vicinity support denser and often different vegetation than the surrounding plains. The improved soil structure, with its network of internal tunnels, allows water to penetrate deeper, making the mounds moist refuges for plants during the dry season.
This effect creates distinct plant communities. Species that thrive in nutrient-rich conditions congregate on and around the mounds. In the dry zones of central Myanmar, this can include species from the Fabaceae (legume) and Verbenaceae families. The ecological impact extends beyond plants. These patches of vigorous vegetation attract herbivores, which in turn attract predators, increasing the overall biodiversity of the region. The mounds persist in the landscape for long periods, influencing soil properties and plant distribution even after a termite colony has died out. These abandoned mounds slowly erode, distributing their concentrated nutrients into the surrounding soil. This long-term nutrient redistribution makes the termites a foundational species for the health of the entire dry zone ecosystem.