Old termite mounds help support high insect biodiversity in tropical rainforests

Living Dicuspiditermes termite mound

A new study by Dr Tom M. Fayle of Queen Mary University of London, Dr Kalsum M. Yusah of the Royal Botanic Gardens, Kew, and Dr Jiri Tuma of the Biology Centre of the Czech Academy of Sciences, Czech Republic, published today in the journal Soil Ecology Letters, shows the importance of old termite mounds as habitats for a wide range of insects and other invertebrates in Bornean tropical rainforest. 

Termites play a critical ecological role in many ecosystems. By building and maintaining their nests and mounds, they influence soil turnover, chemical soil properties, and nutrient distribution. Once these mounds are abandoned by their original builders, they potentially serve as a suitable home for various other animals. Tuma et al took samples of unoccupied mounds of a common termite (Dicuspiditermes spp) and compared the animals with those found in nearby soil. The authors found a high diversity of invertebrates, especially ants, in unoccupied mounds of soil-feeding termites, in both undisturbed and logged rainforest in Borneo. 

 Lead author Dr. Tuma said, “When walking through the rainforest in Borneo, you notice the very apparent mounds built by these soil feeding termites, sometimes found at high densities. However, there is surprisingly little knowledge about their ecological importance as a microhabitat for other species. Much previous work has been carried out on the species that live in large African or Australian termite mounds, but these rainforest termites have received little attention.” The team found that unoccupied mounds had five to nine times higher abundance of insects and other invertebrates than the surrounding soil in undisturbed forest. This boost to biodiversity remained the same in forest that had been logged, although overall abundance of invertebrates was lower. The most commonly found insect group in the unoccupied mounds were ants, which often built their own colonies once termites had left, with 17 different ant species being found. 

Senior author Dr. Fayle said: “These unoccupied mounds are much more important as a habitat for other animals than previously thought. We estimate that they are home to more than 340,000 insect and other invertebrate individuals in every hectare in primary forest, and more than 17,000 individuals per hectare in logged forest. These mounds should be considered as comparable in importance to microhabitats such as dead logs, and should be included in future biodiversity surveys”. 

Co-author Dr Yusah said “Our study demonstrates the broader importance of this group of ecosystem engineers, and has implications for conservation of biodiversity in the face of ongoing anthropogenic habitat change. For example, it may be worth prioritising conservation of areas with high termite diversity, or even considering novel methods such as “planting” termite colonies along with trees during habitat restoration.”