Ants to the Rescue: How Spoil Heaps Turn into Thriving Ecosystems

Mining often leaves behind landscapes we imagine as barren and lifeless. Yet, as PhD student Marie Hovorková discovered, these post-mining “spoil heaps” can host vibrant ant communities that steadily reshape and restore the land. In this interview, Marie shares how ants recolonize these sites—sometimes developing in ways just as rich and diverse as nearby forests—and what this unexpected resilience can teach us about conservation, restoration, and the power of nature to bounce back.

Edited by Gaurav Agavekar and Salvatore Brunetti

MNB: Could you tell us a bit about yourself?

MH: My name is Marie Hovorková. I am a student in the PhD program in Environmental Science at the Institute for Environmental Studies, Charles University, and I am interested in ants and their ecology. More specifically, my PhD thesis is focused on ant communities in endangered grasslands in the White Carpathians, disturbed and restored post-mining ecosystems, and the role of ants in ecosystem restoration and the use of ants in bioindication.

MNB: Could you briefly outline your research on “Consistent successional trajectories of ant species richness, composition, and functional traits on post-mining sites in European deciduous forest” in layman’s terms?

MH: Simply put, our research focused on observing how the ants have been recolonising spoil heaps after brown coal mining. We were interested in changes in the composition of ant communities over the course of time and which environmental parameters influenced these changes. To answer those questions, we used both chronosequence approach, which means that we selected several sites of different ages on the spoil heaps instead of observing a single site for several years or decades and comparing changes that occurred over time on given sites. In our case, we looked at how the ant communities have changed after approximately 20 years, and we had a chronosequence of sites ranging from 1 to 50 years. We also compared sites reclaimed by afforestation with those overgrowing by natural revegetation. We were interested in whether the composition of ant communities would be different between them, as other studies have shown that sites left to spontaneously revegetate often host more species-rich communities with rare and endangered species.

MNB: What is the take-home message of your work?

MH: We found ant communities on spoil heaps to consistently develop towards those in the surrounding landscape. The composition of ant communities was heavily affected by site age and also by parameters related to soil and vegetation development, such as bare soil cover and canopy cover. Surprisingly, there were no differences in the development of ant communities between reclaimed and spontaneously revegetated sites. The number of forest species increased with site age and forest stands aging.

MNB: What was your motivation for this study?

MH: The main motivation was my view on spoil heaps. Initially I viewed spoil heaps and post-mining area on the whole as a desolate wasteland. However, when I started my studies at Charles University, I soon learned that this was not the case and that the situation was often exactly the opposite. While mining activities heavily damage and often basically erase the original landscape, new areas are created in their place. Many of these areas, especially if created by natural revegetation, host rare and endangered species of plants and animals. I found this fascinating and wanted to learn more about this topic.

MNB: What was the biggest obstacle you had to overcome in this project?

MH: One of the biggest obstacles was that mining activities were still ongoing. Due to this, some of the originally sampled sites were destroyed, so we had to select new ones with characteristics that were as similar to the original ones as possible. Another obstacle was the high number of game on the spoil heaps. We wanted to use pitfall traps as a standard method for collecting ants to supplement our data obtained by hand sampling, which was our main method for studying the composition of ant communities. The majority of placed traps were, however, destroyed by wild boars, so we were not able to use this method.

MNB: Do you have any tips for others who are interested in doing related research?

MH: It is important to collaborate with the parties involved and to plan thoroughly.

MNB: Where do you see the future for this particular field of ant research?

MH: There is room for similar studies, which would then allow for synthesis and searching for general rules and patterns. Despite the chronosequences being a good alternative to long-term studies, it would be valuable to perform long-term studies as well, as they are very rarely done in animal studies and may be able to detect subtle and fine-scale changes in communities. Apart from researching the succession of ant communities in post-mining areas, studying the ecosystem services ants might provide in such places and their potential to aid in restoring degraded habitats would be another direction.