ADVERTISEMENT

Dung Beetles: Lending A Hand In Mine Rehabilitation

Opencast mines in South Africa are usually rehabilitated using soil that was stripped from the land prior to mining and stockpiled until it is needed for rehabilitation purposes. The soil is stockpiled for long periods during which essential nutrients required for productive plant growth are lost. When the soil is returned for rehabilitation purposes, heavy vehicles transporting and placing the soil increase the soil compaction to such a degree that water runs off the surface at high velocities, leading to erosion, and, eventually, land degradation. Plant growth is consequently limited due to acidic and impermeable soils with very low fertility, creating an inhospitable environment for the establishment of any biotic community, especially fauna that rely on the presence of vegetation.

Some animals can survive in these limiting environments as long as a food source and appropriate climatic conditions are present. Dung beetles mainly rely on the presence of dung to complete their lifecycles, flying as far as 850 meters (although it is suspected to be even further) to the dung source. As low-intensity grazing is a common post-closure land use for mines in developing countries such as South Africa, dung beetles will occur simultaneously with the presence of cattle.

ADVERTISEMENT

Dung beetles are classified into mainly three groups based on how they process dung. Telecoprids (rollers) roll dung balls away from the dung pat and bury the dung ball elsewhere; endocoprids (dwellers) live and breed inside a dung pat; paracoprids (tunnellers) construct tunnels directly beneath dung pats and create broodball clusters at the bottom of the tunnels. Like termites and ants, dung beetles play important roles in the ecological processes of soil, particularly nutrient cycling. As tunneling dung beetlesā€™ burrowing activities are associated with improved soil bioturbation and aeration, it has been observed that plant growth is enhanced where these insects have been active. It was therefore hypothesized that dung beetle activity would lead to similar enhancements on rehabilitated mine soils, providing that dung beetles could dig into the highly-compacted soil surface.

Our study, funded by Coaltech Research Association and published in the journal Applied Soil Ecology, investigated the effects of tunneling dung beetles on soil and plant properties within confinements that simulated conditions associated with rehabilitated opencast coal mines in South Africa. The confinements were constructed to simulate soil conditions that occur on rehabilitated mines with a soil profile consisting of a layer of waste coal, subsoil, and topsoil, and vegetated with typical mine rehabilitation grass species. Three treatments, namely dung + beetles, dung only, and no dung or beetles, were applied to separate confinements (with three replicates each), where after results were analyzed and compared in terms of the following: water infiltration rate, plant biomass yield and protein content, soil compaction, and soil nutrients. Dung beetles were collected from the wild and bred in a breeding facility before they were used for these experiments.

When dung beetles were placed inside the confinements, it was clear that compacted soil did not present a challenge to them. Dung beetles were found to significantly increase water infiltration rate, thereby reducing the likelihood of erosion on the rehabilitated landscape. As the selected species of dung beetlesā€™ tunnels only go down to approximately 15 cm, water will likely not enter the spoils underneath the soil. Plant growth was similarly improved where dung beetles were active by yielding approximately double as much biomass compared to confinements with only dung and confinements with no dung or beetles.

Adding dung beetles to the conventional mine rehabilitation methods may accelerate the reclamation of post-mining soils and would provide job creation where individuals would need to be trained for dung beetle breeding programs. Although not part of our study, it was observed that dung beetles are capable of breeding in these harsh conditions, where we found brood balls containing eggs at the bottom of tunnels. It would be important to investigate the long-term effects of adding dung beetles and cattle dung to post-mining soils, including possible patterns of ecological succession that would indicate a positive trajectory in mine rehabilitation efforts.

ADVERTISEMENT
These findings are described in the article entitled Dung beetle activity improves herbaceous plant growth and soil properties on confinements simulating reclaimed mined land in South Africa, recently published in the journal Applied Soil Ecology.

Comments

READ THIS NEXT

Impact Of Social Media On HPV Vaccine Uptake

In a recently published study in Vaccine, we explored whether a social media health campaign was successful in increasing human […]

Managing Soil After A Fire

Fire is a natural element of ecosystems that has shaped world biomes as we know them today. With the exception […]

Metric System Chart: Learn How To Convert

Need to understand how to convert between metric and other forms of measurement like the Imperial system? Conversion charts, such […]

ā€œI Donā€™t Want To Take The Perspective Of Minority Group Membersā€: Instructions Enhance Reactance And Non-Compliance

Blatant prejudice against refugees is on the rise in many Western countries1. Can we reduce prejudicial attitudes and promote empathy […]

Dinosaur Era Baby Snake Found In Amber

In something that sounds oddly similar to the plotline from Jurassic Park, scientists have found a remarkably preserved baby snake […]

How Daily Care May Affect Aquatic Organisms: Personal Care Products In Wild Mussels From Coastal Waters

Every day, millions of people enjoy the pleasure and benefits of personal care products (PCPs). From hair colors to lipsticks, […]

Speech Directivity And Vowel Sounds

When we are behind someone who is speaking, we hear them less clearly, and it is more difficult to understand […]

Science Trends is a popular source of science news and education around the world. We cover everything from solar power cell technology to climate change to cancer research. We help hundreds of thousands of people every month learn about the world we live in and the latest scientific breakthroughs. Want to know more?