A Prairie Ecologist’s Perspective on Arbor Day

Today is National Arbor Day – a holiday initiated by J. Sterling Morton right here in my home state of Nebraska.  The idea of Arbor Day is to encourage the planting of trees. However, as a prairie ecologist, I spend considerable effort trying to keep trees from taking over the prairies I manage and/or care about.

As a result, I have some mixed feelings about Arbor Day.

A cottonwood tree in a Platte River prairie at sunrise.

A cottonwood tree in a Platte River prairie at sunrise.  Beautiful, but not without some impacts on prairie ecology.

I don’t harbor any particular enmity toward trees themselves.  In fact, some of my favorite places in Nebraska have fantastic woodlands, including The Nature Conservancy’s Rulo Bluffs Preserve and Niobrara Valley Preserve.  I also really like the trees in my yard – especially the one that produces a big crop of pie cherries each year!

On the other hand, I don’t hesitate to use all necessary force to remove trees from grasslands.  Why?  There are numerous reasons.  Here are a few examples:

– The shade from trees changes the microclimate underneath them, suppressing the growth of many prairie plants and favoring others, including some nasty invasive species that can then spread into prairies.

– Trees completely change the habitat structure of a prairie, making it unsuitable for many wildlife species that rely on wide open habitats.  As trees and shrubs increase in density, prairie animals are forced out.

– Many grassland birds avoid nesting near woodlands, or even lone trees.  There are multiple reasons for this, but a big one is the abundance of predators that hang around in and under trees.  A line of trees along the edge of a prairie creates a wide “dead zone” within which very few prairie bird species will nest.  In landscapes where most prairies are already small and fragmented, the loss of that additional habitat can have serious consequences.

– Once trees and shrubs become established, they tend to promote the establishment of more.  Some spread by rhizomes (underground stems) and all of them are good perch sites for birds, which drop seeds out both ends onto the ground beneath the trees.  Once on the ground, shade from the trees reduces the vigor of prairie plants and helps woody seedlings thrive.  Dense tree and shrub patches can also become fire proof because their shade prevents grass growth beneath them – and it’s grass that carries fire.

Burning prairie can suppress the encroachment of trees, including eastern red cedars.

Burning prairie can suppress the encroachment of trees, including eastern red cedars.

Woody plants, including both trees and shrubs, have always been good at invading prairies but, historically, fires and dry climate helped keep them from becoming established across most of the grasslands of the Great Plains.  Today, fire suppression, landscape fragmentation, and even changing levels of carbon and nitrogen in the atmosphere are giving trees the upper hand.  As a result, my staff and I (ok, mostly my staff nowadays) spend an inordinate amount of time cutting trees down, burning grasslands to kill trees, and treating trees with herbicides.

Can you see why a holiday that promotes tree planting – especially in a grassland state like Nebraska – might make me a little nervous?  There’s absolutely nothing wrong with planting trees, but the kind of trees being planted and the location they’re planted in makes all the difference in the world.

If you live near a prairie, here are two important tips to consider as you prepare to celebrate National Arbor Day by planting a tree (or lots of trees).

1. Do some research on the tree species you plant.  Some species, such as Siberian elm, Russian olive, Autumn olive, and other non-native trees and shrubs can be very invasive in grasslands, quickly spreading by seed far from the parent tree.  A quick internet search using the name of the tree and the word “invasive” will tell you whether or not the tree species you’re considering is one that could cause problems.  However, even many native trees can spread into grasslands, so that leads us to…

2. Carefully consider the location of your proposed tree planting.  As mentioned earlier, even a single tree, let alone a row along the edge or (heaven forbid!) through the middle of a prairie can wreak havoc on grassland birds and other species.  Prairies and their plant and animal inhabitants thrive in wide open habitats; adding trees to those habitats can really mess things up.

By all means, plant trees in your yard, around your farmstead, or in a local park or school.  Trees provide shade, habitat, food, and aesthetic beauty to cities, towns, and acreages, and you should feel good about contributing toward those things.  However, as you celebrate Arbor Day, please don’t forget about prairies, the plants and wildlife that rely on them, and the hard-working prairie ecologists and land managers trying to conserve them.


Happy Arbor Day!

(please celebrate wisely)

If You Play With Fire…

There’s nothing playful about safe and effective prescribed burning.  Too many things can go wrong to take it lightly.  Sometimes, I think people see prescribed fire as something that needs to be done to maintain prairies, but they can’t necessarily point to specific objectives for a particular fire.  Nor can they describe what kind of burning (season, intensity, size, ignition pattern) is needed to achieve those objectives.  Falling into the trap of burning because it seems like the right thing to do leads to two big risks.  First, there’s a good chance that the fires will not be conducted in a way (or at the right time of year) that do much good – and could even be counterproductive.  Second, because prescribed fire can be a hazardous activity, conducting one without clearly defined reasons means taking big risks for no good reason.

A prescribed fire we conducted last week. This one went off without a hitch. Most of them do.

We’ve completed two prescribed fires so far this spring.  As always, we spend way more time planning our fires than implementing them.  That planning starts with setting clear ecological objectives (defining why we’re burning in the first place) which dictate the location, size, season, and even the tactics used during the fire.  Once we know what we’re aiming for, we write a burn plan that can help us achieve that in the safest way possible.  Our plans detail the kinds of weather conditions and tactics needed to be successful, but also spend a lot of time on contingencies.  What will we do if the fire gets away?  What does the surrounding landscape offer in terms of safe areas and threats in the case of an escaped fire.  How will we respond if someone gets hurt?  For me, writing a good burn plan means thinking through all the worst case scenarios.  There’s nothing fun about it.

Unfortunately, even after all that planning, things still go wrong.  Last spring, I wrote about a burn we did in which we ran into repeated equipment issues, and had to shut down for a while until we could get re-equipped and complete the burn.  In another fire last year, I overestimated the strength of our blackline containing the fire, and the wind-driven head fire jumped it in one place, forcing us to quickly chase it down.  This spring, our first prescribed burn started out well, but the wind came up sooner than had been forecast, and we shut the fire down because a Red Flag Warning was issued.  In all of those cases, there were no serious repercussions, and our training and planning helped us deal effectively with unexpected circumstances.  Because we’d planned for each contingency, everyone knew how to react when the time came.  No property was damaged and no one got hurt.

The threat of injury is what makes prescribed fire especially stressful for me.  Between potential equipment mishaps and quickly-changing weather and fire conditions, there are numerous opportunities for someone to get hurt.  So far, I’ve never had anyone get injured on a fire I’ve been a part of, but that fortunate record certainly isn’t making me complacent.  As if I needed a reminder of the danger, one of our crew was helping a partner organization with a fire last week and suffered some slight burns on his neck and face while trying to extinguish a drip torch.  After trying and failing to smother the flame at the tip of the torch with a gloved hand (per protocol) the crew member then tried to blow the flame out, and some of the burning torch fuel splattered onto the cotton bandana around his neck.  Before he could get the bandana off of his head, he suffered small burns in several places.  After a quick trip to a nearby medical clinic, he was fine – though he had to shave off the remainder of his singed beard.

It appears there were several things that contributed to the torch incident, possibly including some issues with the torch itself that caused excessive fuel to build up in the torch’s tip, making it particularly difficult to extinguish.  After the fire was wrapped up there was considerable discussion about what happened, and hopefully we all learned some things that will make us all safer in the future.  Regardless of the cause, however, the aspect of the event that struck me the most was that our crew member was injured doing something he had done hundreds of times before.  It’s sobering to know that something as mundane as extinguishing a torch led to injury, and that it could have been much worse than it was.

Lighting the head fire of our prescribed burn last week. This was the easy part. The planning, training, weather monitoring, equipment preparation, and black-lining were all done. (Not pictured - the knot in my stomach)

I am a strong and vocal advocate for the use of prescribed fire to manage both private and public lands.  On the other hand, prescribed burning is not a sport, it’s a tool, and it’s a tool that we should employ strategically – not for fun, or without specific objectives in mind.  If someone can’t clearly explain what they’re trying to achieve by conducting a particular burn, I don’t know how they can justify taking the risk of dropping a match.  In addition, if some doesn’t have a clear and detailed plan for how to ignite and contain a fire, and how to respond when things go wrong, I don’t think they have any business lighting that fire in the first place. 

I know people that really enjoy conducting prescribed fires.  Frankly, those people make me nervous, especially if they’re in charge.  I don’t dislike prescribed burning, and I get a feeling of satisfaction whenever we wrap one up successfully – especially because I can appreciate the ecological benefits of doing so.  But while there is active fire on the ground, there’s a knot in my stomach, and that knot subsides slowly, even after the last of the smoke has faded into the sky. 

It’s fantastic that the use of prescribed fire is growing among prairie landowners and land managers.  More importantly, the greatly increased availability of training and equipment means that we’re not only burning more acres, but we’re also more sophisticated – and hopefully safer – as we do so.  However, things will still go wrong.  Property will be damaged and people will get hurt.  It can happen during even the simplest fires.  That doesn’t mean we shouldn’t burn.  It does, however, mean that we should burn only when it can be done safely and only when we can burn in ways that achieve important objectives.  Otherwise, the risk can quickly outweigh the rewards.

Be safe out there…


You may be interested to read these previous posts about prescribed fire:

The importance of equipment redundancy in prescribed fire.

Why prescribed fire doesn’t contribute to global warming.