MANHATTAN (KSNT) – The results of a recent study focusing on the relationship between bison and the tallgrass prairie have been released and show some surprising conclusions.
The study was conducted by a team from Kansas State University. It focused on observing the impact of reintroducing bison to the tallgrass prairie. The team reviewed more than 30 years of information from the Konza Prairie Biological Station. Their study was published in the Proceedings of the National Academy of Science journal.
The study found plant communities not only experienced an increase in diversity, but also became more resilient through the most extreme drought in four decades. The gains recorded by the study are among the largest recorded increases in species richness.
“Bison were an integral part of North American grasslands before they were abruptly removed from over 99% of the Great Plains,” said Zak Ratajczak, assistant professor of biology and lead researcher. “This removal of bison occurred before quantitative records and therefore, the effects of their removal are largely unknown.”
The Flint Hills ecoregion was chosen because it’s the largest remaining tallgrass prairie in the Great Plains. Researchers examined plant community composition and diversity using three treatments designed to capture characteristic management regimes:
- No mega-grazers were present.
- Bison were reintroduced and allowed to graze year-round.
- Or, domestic cattle were introduced and allowed to graze during the growing season.
“Our results suggest that many grasslands in the central Great Plains have substantially lower plant biodiversity than would have occurred before bison were widely wiped out,” Ratajczak said. “Returning or ‘rewilding’ native megafauna could help to restore grassland biodiversity.”
The study also found cattle had a positive impact on plant diversity, compared to having no large grazers present. However, increases in plant species richness were significantly smaller than those caused by bison.
“I think this study also shows that cattle can have a largely positive impact on biodiversity conservation in our region, especially considering that many in cattle production conduct the prescribed fires that have kept these grasslands from becoming woodlands,” Ratajczak said. “What this study really suggests is that when it’s economically and ecologically feasible, reintroducing bison might have an even more positive effect on biodiversity conservation.”
Researchers also sought to find out how bison impact plant community resilience to climate extremes. After surviving climate extremes, native plant species in the bison-grazed area were more resilient to drought.
“The resilience we found in the bison grasslands is also consistent with the idea that diversity promotes ecological resilience,” Ratajczak said. “And this resilience will only become more important if our climate becomes more extreme.”
The study was funded by six grants of over $31.6 million since 1980. Research was conducted by distinguished faculty from K-State University, the University of New Mexico, the University of North Carolina and Colorado State University.