Yellowstone wolves and willows The study looking to refute Ripple\u2019s claim was led by Daniel R. MacNulty, wildlife ecologist. His research focuses on predator prey<\/a> dynamics and long term carnivore ecology.<\/p>\n The 1,500 percent figure came from converting willow height into volume with a formula that also uses height to define volume. That setup creates a tautological model, a circular method where the output reuses its own input.<\/p>\n MacNulty explained that Ripple\u2019s team had argued that carnivore recovery created one of the world\u2019s strongest trophic cascades, ecological chain reactions where predators indirectly boost plant growth by controlling herbivores. <\/p>\n He added that their conclusion does not hold up because it depended on circular reasoning and violated key modeling assumptions.<\/p>\n A sound test needs independent evidence that is not built from the same measurement. Otherwise, the model will look strong even when biology has not changed.<\/p>\n Changing the math<\/p>\n The volume model assumed dome-like crowns that look like half ellipsoids, which is rare in heavily browsed shrubs. <\/p>\n Many Yellowstone willows<\/a> grew under sustained browsing, producing distorted shapes that break the model\u2019s key assumption.<\/p>\n That means volume was likely overestimated in later years, precisely when some plants grew taller. The mismatch between real crowns and the assumed geometry matters for any volume estimate.<\/p>\n Crowns also vary by species and site, which the model did not capture well. Those differences add bias when a single formula is stretched across a complex landscape.<\/p>\n Foundation for wolves and willows<\/p>\n The trend also mixed different field plots across years, which weakens a before and after comparison. Only a few plots matched between 2001 and 2020, so the baseline was shaky from the start.<\/p>\n Under those conditions, the computed log response ratio, a standardized measure of proportional change, can inflate the apparent effect. The method then blends real change with sampling shifts that look like growth.<\/p>\n Matching the same plants or the same plots over time would fix that issue. Without that match, the loudest signal can come from where and when you sample.<\/p>\n Ripple\u2019s global comparison leaned on a classic meta-analysis<\/a> that assumes systems settle into equilibrium by study end. Yellowstone has not settled, because hydrology and herbivory still vary across sites.<\/p>\n Water limits make that clear. A long term field experiment showed willows with low water tables stayed short even when elk were kept out.<\/p>\n Beaver<\/a> loss and stream incision still shape floodplains, which holds water tables down. That legacy slows willow growth even as predators change elk behavior.<\/p>\n Photos and missing causes<\/p>\n Selective photo pairs can make rare success look like the rule, especially when images come from the same bend in a creek. Recovery is patchy across valleys, so pictures alone do not prove a system wide surge.<\/p>\n Elk also move outside the park where hunting occurs, which changes browsing pressure<\/a> in the park.<\/p>\n The researchers noted that once the analytical problems were addressed, there was no evidence that predator recovery led to a large or system-wide increase in willow growth. <\/p>\n They emphasized that the goal was to clarify the evidence rather than diminish the ecological role of predators.<\/p>\n What the evidence really says<\/p>\n Hobbs and colleagues ran a factorial field study across two decades and found only modest willow responses<\/a> to wolves. Their plots showed that water, browsing, and site conditions set the pace of growth.<\/p>\n MacNulty\u2019s team reconciles those results with Ripple\u2019s claims by showing how a circular model and mismatched plots magnified a single number. <\/p>\n The take home is simple and careful, predator effects in Yellowstone are real but context dependent.<\/p>\n Numbers still matter, but they need context drawn from field reality. That is why the authors combined statistics with site history and hydrology.<\/p>\n Wolves, willows, and science<\/p>\n Predators still matter, and no one is erasing their role in this ecosystem. The current picture just shows a slower and more uneven plant response than a single number suggests.<\/p>\n Yellowstone is teaching an old lesson about complex food webs and shifting water. Patience and careful design will reveal where wolves<\/a> matter most for plants.<\/p>\n For readers, the lesson is plain. Big claims deserve clear tests that do not stack the deck or skip steps.<\/p>\n The study is published in Global Ecology and Conservation<\/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.\u00a0<\/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":"In a new peer reviewed comment, researchers say Yellowstone\u2019s wolf story needs a reset. The researchers challenged a…\n","protected":false},"author":2,"featured_media":294617,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[64,63,128,338],"class_list":{"0":"post-294616","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-wildlife","8":"tag-au","9":"tag-australia","10":"tag-science","11":"tag-wildlife"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/294616","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=294616"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/294616\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/294617"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=294616"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=294616"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=294616"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n
\n ![\"EarthSnap\"\/](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/11\/earthsnap-banner-news.webp.webp\")
\n<\/a><\/p>\n