Category Archives: Ask an Expert

Why You Should Know About the Eastern Redcedar Science Literacy Project

This isn’t how America’s Great Plains are supposed to look.

The Western Working Lands for Wildlife initiatives like the Lesser Prairie-Chicken Initiative (LPCI) and the Sage Grouse Initiative (SGI) focus on the concept of rangeland resiliency. In short, rangeland resiliency is the capacity for rangeland to absorb “disturbance,” like drought or fire, without becoming degraded. Resilient rangelands continue to function in the face of disturbance, or they bounce back from periodic disturbances and quickly return to healthy, productive ecosystems after their initial collapse. Rangelands that lack resiliency struggle to recover from disturbances, do not return to their pre-disturbance structure and function, and instead transition to an alternative state that is often less desirable for both agriculture and wildlife.

In the West, Working Lands for Wildlife works to improve rangeland resiliency on private lands across the prairies and grasslands of the Great Plains and the 11 states with sagebrush-steppe landscapes. Many challenges threaten rangeland resiliency in this huge region. Conversion of productive grasslands or sagebrush-steppe to closed-canopy woodlands is one of the biggest ones.

Trees are, of course, historic residents of the West. But over the last 150 years, conifer trees have expanded from their historic range into previously tree-less landscapes. In the sagebrush-steppe, juniper trees are the main culprit. In the Great Plains, Eastern redcedar is perhaps the most notorious example of a native tree turned invasive, and it’s moving into new territory at an alarming rate. Nebraska is now at the front lines of cedar invasion: nearly half a million acres of grazing lands have been lost since 2000 because of expanding redcedar forests.

Across all of the regions, this change is creating numerous impacts.

  • As conifers encroach on grasslands and sagebrush-steppe, wildlife like the lesser prairie-chicken, the greater prairie chicken, and the greater sage grouse move out. Research by SGI and LPCI has shown that as few as one to two trees per acre will cause the birds to leave.
  • Grasslands and sagebrush-steppe are remarkably diverse ecosystems. As they change into forests, much of that biodiversity is lost, and native grassland- and sagebrush-dependent species are negatively affected.
  • Trees use more water than the native plants in prairies and sagebrush range. The trees suck up water that is no longer available to native plants, aquatic life, agriculture, and communities.
  • Woody species also increase the negative impacts from wildfires. The trees fuel more intense wildfires, which impact wildlife, encourage invasive weeds, stress communities, and more.

Nebraska is on the front lines of an eastern redcedar invasion as illustrated by this photo from the Loess Canyons area. Photo by Dirac Twidwell, UNL

One of the leading researchers on the impacts these trees are having on the Great Plains is Dr. Dirac Twidwell of the University of Nebraska-Lincoln. In addition to his research efforts, Dr. Twidwell is also the Associate Director for the new Center for Resilience at the University of Nebraska.

Dr. Twidwell and his colleagues at UNL launched the “Eastern Redcedar Science Literacy Project” in a two-part effort to study the impacts of Eastern redcedars and other conifers and to share their findings with the public. We sat down with Dr. Twidwell to talk about his research, the Project, what this threat means for wildlife and humans, and what land owners and managers can do about it.


Will you start by introducing the Eastern Redcedar Science Literacy Project? What is it? When did it start?

The Eastern Redcedar Science Literacy Project (ERCSLP) is the most comprehensive resource for understanding the spread and impacts of Eastern redcedar, one of the most well-studied and problematic invasive species in North America. I want to acknowledge the contributions of all the researchers and graduate students who helped create the ERCSLP, especially Christine Bielski, a graduate student who led the project’s development.

The project started in response to the increasing demand from private citizens and natural resource professionals for more information on the consequences of the Eastern redcedar invasion. As we studied these impacts, it became increasingly clear that the general public was unaware or ill-informed about the breadth and depth of science related to Eastern redcedars.

ERCSLP homepage image

The Eastern Redcedar Science Literacy Project website is a one-stop-shop for the most up-to-date eastern redcedar science and research.

What was your motivation for creating the project? What are its goals?

As a scientist, I increasingly feel an ethical responsibility to disseminate decades of research findings to the general public, politicians, K-12 educators, natural resource professionals, city planners, and the next generation of scientists. Scientists have reached clear consensus about the problems posed by Eastern redcedar invasions. The ERCSLP provides the facts that should be used to question existing land management practices, to critique existing government policies and future proposals, and to hopefully create a more literate and informed society. My goal is that every citizen in the Great Plains knows the costs of Eastern redcedar invasion and the underlying reasons for why scientists continue to draw attention to this environmental problem.

How did we get here? What allowed eastern redcedar and other conifer trees to expand their ranges so dramatically? 

These are two of the most common questions we are asked, and we actually developed a FAQ section for scientists because they were brought up so frequently (link). Eastern redcedar, while historically rare, has been part of the Great Plains ecosystem for millennia, but it is one of the most fire-sensitive plants in the region. It cannot resprout after a fire, so its survival strategy is to escape fire damage. Historically, fire burned so frequently, with such intensity, and across such a large part of the Great Plains each year that Eastern redcedar distribution was effectively contained in areas where fire didn’t reach.

The removal of fire’s historical control process, coupled with ubiquitous planting and distribution of Eastern redcedar, set the stage for widespread invasion and the proliferation of cedar across multiple states today.

Woody species map

This image shows the extent that woody species, led by eastern redcedars, have expanded throughout the Great Plains from 2000-2018. Image courtesy of UNL.

Why is there a such a strong sense of urgency in the Project’s language?

The strong sense of urgency in the Project’s language matches the overall narrative of scientific experts. Many people seem to expect scientists to emphasize technical points and use an almost robotic style when they communicate with the public. But there is strong concern voiced in the scientific community about the lack of attention to this environmental challenge that spans multiple states. That is what this site is all about. Increasing literacy is not just about knowing the facts, but also understanding the tone and urgency from the scientists that have spent their entire careers studying this issue.

Why tackle this problem now?

The clock is ticking to conserve the last remaining prairie regions in the central and southern Great Plains. Cedar distribution is rapidly expanding, and I am part of a group of scientists tracking its change and impact on rangeland resources. No state has effectively prevented cedar invasion from overtaking rangelands, and no state has restored large areas of rangeland after conversion occurred. The ranching community is particularly affected, since the transition from grassland to cedar woodland can displace 75% or more of rangeland productivity used for livestock production. It is simply in our best interests to tackle this problem and avoid further losses to this and other ecosystem services.

The Project’s website says that “Eastern redcedar is considered one of the greatest threats to human well-being and to the unique flora and fauna of the Great Plains.” Will you share some of the impacts to human well-being that eastern redcedars pose?

The impacts of Eastern redcedar to human well-being are very well studied. The negative consequences span wildlife and biodiversity, livestock productivity, water quality and quantity, increased wildfire danger and a reduced ability for firefighters to successfully suppress wildfires, and reductions in school funding for public education. Recent research has linked cedar impacts to today’s allergy problems and insect-based disease vectors. Very few plants affect this number and array of resources that are so important to our lives.

Are there specific types of wildlife that are more impacted by encroaching conifers than others?

Cedar so severely changes the structure and function of rangelands over time that it affects all grass-dependent species. Multiple species become rare or locally extinct after conversion to cedar woodlands. We cover this in detail in the Science Literacy webpage. However, it is true that some wildlife are more sensitive than others. For example, prairie chickens are particularly sensitive and decline at very low levels of cedar encroachment.

Aren’t there also benefits to wildlife? How do you reconcile negative consequences versus benefits?

One of the most common misconceptions is that because wildlife are seen using cedar trees, they must need them. There is a video series where scientists breakdown these types of misconceptions. Dr. Dwayne Elmore, from Oklahoma State, has a great set of points in his video and the following powerful quote, “No wildlife require cedar.” This is an important point. While wildlife might use cedar for various purposes, those uses do not outweigh the consequences to wildlife when their habitat is lost to an unsuitable, alternative ecosystem.

In short, the displacement of native species with habitat generalists that tolerate invading trees should not be acceptable to the conservation community.

Are there examples where management is sustaining rangeland in the face of cedar invasions?

Yes, there are two examples: The Flint Hills in Kansas and the Loess Canyons area in Nebraska.

In the Flint Hills, there is still a culture of fire and a relatively intact fire regime across approximately 3 million acres. It is a great example of resilient rangelands where the intact disturbance regimes build resilience, which helps prevent major problems from occurring. Fire in this region is effectively preventing the establishment and spread of Eastern redcedar.

Kansas’ Flint Hills still have an intact fire regime, which has helped prevent eastern redcedar trees from encroaching on the valuable grasslands. Photo: Jim Minnerath, USFWS via Flickr.

In the Loess Canyons area, landowners established prescribed burn associations to restore fire in an attempt to regain the livestock productivity and wildlife diversity lost to Eastern redcedar. It is one of the most heavily invaded ecoregions of Nebraska, yet landowners have been able to rebuild a fire culture and are now cooperating on over 200,000 acres. Since 2013, cedar cover has stabilized and stopped its steadily increasing trend. This is the first example we have found where a community adapted their management practices and restored fire back into the system. The result is the stabilization of a region that had become heavily infested with Eastern redcedar.

Prescribed fire in the Loess Canyons

Prescribed fire like this have helped landowners in the Loess Canyons area of NE stem the invasion of eastern redcedar trees. Photo: Dirac Twidwell, UNL

What’s next for the Eastern Redcedar Science Literacy Project?

The ERCSLP was created to meet landowner needs for communication, and we foresee it continuing to evolve in ways that meets their needs in the future. Right now, we are creating landowner stories across the Great Plains so that people better understand their legacy and management challenge.

If you could leave readers with one key take away, what would it be?

I would actually say there are two key takeaways: The first is Prevent, Prevent, Prevent. Do not underestimate how difficult it is to restore iconic rangeland regions after cedar compromises its integrity and resilience. The second is that loads of scientific evidence counters the myth that converting grassland ecosystems to forested ecosystems will actually benefit ecosystem services and human well-being.

The conversion of grassland to cedar forest does not support the same amount of diversity, agricultural productivity, water resources, or protection from wildfire risk. Sure, some species – especially generalists – use cedar trees (and other conifers), but native grassland species are reliant upon large areas of grasslands and they require those grasslands to remain healthy and tree-free. We shouldn’t jeopardize the future of those grassland-dependent species or other critical ecosystem services simply because a few localized benefits are observed when these trees invade.

Meet the Expert

Do you have redcedars in your yard?

Dirac Twidwell

Dr. Dirac Twidwell. Photo courtesy of UNL.

My family and I just bought a property, and it happens to have lots of Eastern redcedar. I look forward to teaching my kids proper rangeland management, so I would enjoy answering this question again in a couple of years.

What is your role with Working Lands for Wildlife?

I am a science partner with Working Lands for Wildlife and share the philosophy of scaling up conservation for future generations to enjoy productive and diverse ecosystems. My aim is to co-produce science that can help the team address some of the grand challenges we face in rangelands and to better unify expertise across private-public-academic partners, especially in the Great Plains. More importantly, being involved in Working Lands for Wildlife helps me better understand how to develop use-inspired science.

What do you like to do in your free time?

Family, fishing, and travel. I also better mention that I am a lifelong St. Louis Blues Hockey fan since they won their first Stanley Cup this year!