Termites, ants and earthworms are widespread around the world and make up a significant proportion - both in numbers and biomass - of soil invertebrates. These "ecosystem engineers" contribute to soil mixing by creating unique structures such as termite mounds, ant nests and earthworm tunnels. These change the microenvironment and provide both food and habitats for other biological groups. They therefore play an important role in the nutrient cycle and the preservation of biodiversity.
Over 1000 scientific articles from six continents analyzed
An international research team led by Sun Yat-sen University in Guangzhou (China) and with the participation of iDiv’s synthesis center sDiv analyzed the soil-improving effect of the three most important groups of invertebrates in various ecosystems worldwide. To do this, they evaluated more than 1000 specialist articles from six continents.The scientists found that all three groups of invertebrates increased plant biomass, soil microbial biomass and soil respiration by improving macronutrients in the soil. As termites prefer warmer climates, they improve soil respiration and plant biomass especially in warmer regions; the strongest effects were seen in the tropics. As previous studies show that global warming could drive wood decomposition by termites, this could enhance net carbon sequestration in and around termite-created structures.
From tropical to arid zones: important drivers of plant biomass and fitness
Termites and ants play an important role in increasing plant productivity by counteracting phosphorus and nitrogen limitation in tropical and temperate regions, respectively. In phosphorus-poor regions, termite mounds help to increase phosphorus levels in plants and soils, thereby increasing plant biomass. Ant hills, on the other hand, significantly increase the nitrogen content of plants, which also leads to an increase in plant biomass, particularly in nitrogen-poor regions. Prof. Nico Eisenhauer, research group leader at iDiv and co-leader of the sDiv group sOilFauna, concludes: "These results indicate that soil invertebrates make a significant contribution to natural carbon sequestration in terrestrial ecosystems."The new results also suggest that the effect of termites and earthworms on the fitness of plants under dry conditions could be even greater. In tropical rainforests, for example, higher termite activity was observed after drought events. Compared to forests without termites, this improved soil moisture, the survival rate of young plants, the decomposition rate of litter/wood and the nutrient heterogeneity of the soil. Although earthworms are less abundant in arid regions, their burrowing activity helps plant roots in arid ecosystems to take up the limited nutrients available in deeper soil layers.
The researchers emphasize that the three groups of invertebrates studied contribute to more nutrient-rich zones for plants and soil microorganisms. Since environmental factors influence many of the soil-improving effects of termites, ants and earthworms, environmental changes could also affect the ecosystem functions and biochemical cycles that invertebrates help to shape. We know that global climate change, with its extreme events and intensification of land use, is threatening ants, earthworms and termites. It is time to recognize their importance for the functioning of ecosystems and protect them accordingly," says Nico Eisenhauer.
a. supported by the German Research Foundation (DFG; FZT-118). It is the result of an international collaboration in which members of the sDiv working group sOilFauna were also involved. iDiv’s synthesis center sDiv finances working group meetings in which researchers from all over the world work together on scientific questions.
