Reintroducing bison to Kansas prairies doubled native plant diversity over decades, helping grasslands recover from drought and resist tree growth.<\/p>\n
In October 1987, a small herd of bison stepped onto a tallgrass prairie in the Flint Hills of northeastern Kansas. Bison had been gone from the state for about a century.<\/p>\n
Nearly three decades of records later, scientists found that the grazers had roughly doubled the number of native plant species growing where they roamed, compared with prairie left ungrazed.<\/p>\n
The study, published in 2022, followed plant communities at Konza Prairie Biological Station for 29 years. The gains in diversity kept building over time and recovered after one of the harshest droughts the region had seen in decades.<\/p>\n
Thirty bison, one long experiment<\/p>\n
About 30 bison were introduced to Konza in 1987, according to the station\u2019s environmental education program<\/a>. The herd has since grown to roughly 300 animals that roam about 2,400 acres (970 hectares) year-round, without supplemental feed.<\/p>\n The site covers about 8,600 acres (3,480 hectares). It is owned mainly by The Nature Conservancy<\/a> and run as a field research station by Kansas State University\u2019s Division of Biology.<\/p>\n That setup allowed researchers to compare three kinds of prairie side by side. Some watersheds had no large grazers, some had bison all year, and others had cattle during the growing season, from May to September.<\/p>\n The project was led by Zak Ratajczak, an assistant professor of biology at Kansas State University<\/a> at the time of publication. Co-authors came from several universities, including the University of New Mexico<\/a> and Colorado State University<\/a>.<\/p>\n \u201cBison were an integral part of North American grasslands before they were abruptly removed from over 99% of the Great Plains,\u201d said Ratajczak.<\/p>\n What bison do to a prairie<\/p>\n In bison pastures, native plant species richness was 103 percent higher than in ungrazed areas when measured in small plots of about 108 square feet (10 square meters). At the scale of whole watersheds, the increase was 86 percent.<\/p>\n The main reason lies in what bison eat. They feed mostly on dominant grasses such as big bluestem and little bluestem, which tend to crowd out other plants when left unchecked.<\/p>\n By cropping those grasses, the animals open up light and space for wildflowers and other broadleaf plants. Konza\u2019s education program notes that these plants, along with annual species, are more common in bison pastures.<\/p>\n Bison also graze in a patchy way. They return to the same spots and keep them short, creating \u201cgrazing lawns\u201d that sit beside taller, ungrazed stands.<\/p>\n That mix of short and tall vegetation gives more species a place to grow. Similar effects have been reported in Yellowstone, where heavy bison grazing<\/a> sped up nutrient cycling while plant productivity and soil carbon held steady.<\/p>\n Impact of cattle vs. bison<\/p>\n Cattle also raised plant diversity at Konza, but the increase was less than half of what bison achieved. Cattle tend to graze smaller, more uniform patches and are present only part of the year.<\/p>\n The researchers did not frame the results as a case against ranching. Cattle still raised diversity compared with having no large grazers at all.<\/p>\n \u201cI 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,\u201d said Ratajczak.<\/p>\n \u201cWhat this study really suggests is that when it\u2019s economically and ecologically feasible, reintroducing bison might have an even more positive effect on biodiversity conservation,\u201d he added.<\/p>\n How livestock are managed matters elsewhere too. In Inner Mongolia, scientists have used drones to detect early grassland stress<\/a> as grazing pressure rises.<\/p>\n Surviving the worst drought<\/p>\n The long record also captured a severe test. During the study, the Great Plains went through one of the most extreme droughts recorded since the Dust Bowl years of the 1930s.<\/p>\n Native plant richness in the bison pastures dipped at first. Afterward, it returned to the upward trend seen before the drought, rather than settling at a lower level.<\/p>\n \u201cThe resilience we found in the bison grasslands is also consistent with the idea that diversity promotes ecological resilience,\u201d said Ratajczak. \u201cAnd this resilience will only become more important if our climate becomes more extreme.\u201d<\/p>\n That point carries weight as grasslands face hotter, drier conditions. One recent analysis warned that up to half of the world\u2019s key grazing land<\/a> could become unsuitable for pastoralism by 2100.<\/p>\n What newer research adds<\/p>\n Konza\u2019s experiment has continued since the 2022 paper. In October 2025, a team including Ratajczak reported results from a 30-year comparison in areas where fire had been suppressed.<\/p>\n Without regular burning, tallgrass prairie tends to fill in with eastern red cedar and other trees. Fire is the usual tool for holding them back, as studies of controlled burns<\/a> in other grasslands have shown.<\/p>\n In the unburned Konza areas, bison seemed to act as a brake on tree expansion. The team found lower tree cover and more short grass species where bison grazed, likely due to occasional browsing and physical disturbance.<\/p>\n Native plant species richness was 97 percent higher in bison-grazed uplands and 38 percent higher in lowlands, compared with ungrazed areas. The findings appeared in the journal Ecological Applications<\/a>.<\/p>\n Lessons for grassland restoration<\/p>\n Tallgrass prairie once covered more than 170 million acres (69 million hectares) of North America. Today, only about 4 percent remains, according to The Nature Conservancy, and the Flint Hills hold roughly two-thirds of it.<\/p>\n \u201cOur 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,\u201d said Ratajczak. \u201cReturning or \u2018rewilding\u2019 native megafauna could help to restore grassland biodiversity.\u201d<\/p>\n Bison are only part of the picture. Smaller animals such as prairie dogs and grasshoppers can also act as grassland engineers<\/a>, shaping how nutrients move through the soil.<\/p>\n The gains in plant diversity may matter well beyond the plants themselves. Doug Levey, a program director at the U.S. National Science Foundation<\/a>, commented on the wider significance of the findings.<\/p>\n \u201cWe are so accustomed to seeing prairies without bison that we\u2019ve overlooked how their reintroduction can have positive effects across the entire plant community. More diverse plant communities lead to more diverse communities of insects, birds and mammals,\u201d he said.<\/p>\n The full study was published in the journal Proceedings of the National Academy of Sciences<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Reintroducing bison to Kansas prairies doubled native plant diversity over decades, helping grasslands recover from drought and resist…\n","protected":false},"author":2,"featured_media":879711,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[51],"tags":[79,201],"class_list":["post-879710","post","type-post","status-publish","format-standard","has-post-thumbnail","category-wildlife","tag-science","tag-wildlife"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/879710","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/comments?post=879710"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/posts\/879710\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media\/879711"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/media?parent=879710"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/categories?post=879710"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us\/wp-json\/wp\/v2\/tags?post=879710"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}