Measuring the health of an entire ecosystem is a huge task. Often scientists look at one group of animals or plants as a metric of how well an ecosystem is working, and one good proxy is ant communities. The diversity of ant species in an area can indicate how suitable an ecosystem is for these tiny workers - who perform important ecological roles, from dispersing seeds to breaking down wood and returning the nutrients to the soil - as well as how amenable that place is for as their larger mammalian, reptilian, and plant counterparts.

Aside from performing so many ecological roles, ants are also relatively easy to survey (see the video below for an example of how researchers study ants) making them an ideal proxy for the success of ecological restoration like reforestation. Compared to natural regeneration, or leaving an area to recover from some disturbance on its own, active restoration requires some investment of time, money, and resources. Active restoration can be worth the extra input if it accelerates or increases the recovery of disturbed places, so measuring its effects on the ant community under different conditions can help us better repair the damage we (or natural forces like hurricanes and fires) have caused to ecosystems.

In March of this year, researchers at the Federal Rural University of Rio de Janeiro, Brazil, published a paper that looked at previous studies done on ant communities in restoration projects around the world. They evaluated the differences in the number of ant species and functional groups (groups of ant species that have similar characteristics) between restored areas and similar undisturbed areas. Measuring both the number of species and number of functional groups present in an area is important because when multiple species perform the same ecological roles, an ecosystem is more resilient to environmental change. Selected studies included temperate and tropical ecosystems, former mines and pastures, and different restoration ages, allowing the researchers to gauge recovery speed and test for effects of land use history and ecosystem type on the ant communities. 

Overall, ant communities in restored ecosystems appear to regain functional richness more quickly than species richness, implying low resilience in these areas. This does not mean that restoration is ineffective, but rather underscores the fragility of recovering ecosystems and the importance of preventing disturbance when possible. Restoration ecologists and practitioners might also improve restoration success by facilitating the recovery of species diversity.