Burning is a Critical Component of Ecosystem Restoration and Forest Management

A major component to ecosystem management in Missouri and much of the world is burning. Every forest, woodland, savanna, glade, and prairie in Missouri has a history of fire. The indigenous peoples used fire to manage for agriculture and making things like arrow shafts and bows, spears, tools, medicines, and lodges. The indigenous primarily relied on small acreage, cool fires (mild intensity) that were conducted frequently. Dendrochronologist are finding records in tree rings of hot fires that were also a historical component of Missouri ecology. A now extinct grove of chestnuts east of Missouri was found by researchers to be managed with fire for over 4,000 years.

The species of plants and animals that lived on the landscape were a result of fire. Oaks compete very well in fire dominated ecosystems. Many of the native shrubs, grasses, and forbs found on the floors of Missouri's woodlands are fire dependent. The glades of the Ozarks are full of plants that thrive with frequent fire.

We are seeing that removing fire changes the plants and animals we find in Missouri's woodlands and forest. Most of the woodlands haven't had fire in a century. Some of the old-timers I meet tell me they remember fires in the woods when they were younger so we know fires were still being used in our forest more recently. The lack of fire has allowed woodlands and forest to become overcrowded where dominant trees don't have enough spacing to be healthy. The overcrowded trees all become more vulnerable to sickness and death, and much slower growth rates.

The overcrowded trees have a major effect on the understory. Oak seedlings need sunlight to grow. The overcrowded trees in the overstory shades the developing seedlings and most of the oak seedlings die. In their place we are seeing non-oak species that are shade-tolerant, and fire-intolerant species that dominate the seedling and understory layers.

Given enough time the fire-intolerant and shade tolerants grow into the midstory and eventually the overstory. Tree species like sugar maple, hackberry, elm, ash, hickory, and blackgum, and shrub species like ironwood, eastern redbud, spicebush, and dogwood are found dominating in these overcrowded, fire suppressed woodlands.

If the growth of these trees is allowed to continue there are no oak replacements for the large overstory oak trees when they are harvested or die naturally. This leads to a conversion from an oak forest type to a non-oak forest type, which is largely unfavorable for various reasons. For one, acorns are a winter staple for many Missouri wildlife species. When we lose the oaks and acorns, the starving period of winter for wildlife lengthens and intensifies, and the wildlife abundance and diversity changes too.

The increased shade lowers the abundance and diversity of spring and summer forbes and grasses growing on the floor. Wildlife lose important forage during the growing season as a result. The lack of abundance and diversity of forbs and shrubs changes the soil biology, which effects the trees ability to digest nutrients, causing the trees to suffer with low health and increased vulnerability to death.

This story of the value of oaks can be expanded in volumes. Ecosystems in Missouri are largely fire-dependent. People were everywhere burning small tracts of forest, for thousands of years. We inherited fire-dependent ecosystems from the people that managed the great diversity we enjoy today. The chestnut grove managed for over 4,000 years is just one example. The reason the eastern USA has so many edible nut trees, including the once widespread chestnut, was because people were out there everywhere lighting fires for thousands of years.

But the land managers, and the management goals and strategies, changed. The early settlers and colonists in Missouri used fire to remove the forest and convert it to grasslands for grazing livestock and planting crops, like what we see happening in the Amazon forest today. The settlers burned higher intensity fires and more frequently than the indigenous people. The goal was to get the great forest out of the way and grow surplus livestock and monoculture crops in full sunlight.

After some time the increased burning caused concern as Missouri's forest were disappearing, the wildlife was also dissapearing, What was left was sick and vulnerable. We have considerably more forest today than in the late 1800's and early 1900's. Those settlers and early colonizers were professional land clearers.

In the first half of the 20th century Missouri's people began a period of banning burning so forests and wildlife could recover. The Missouri Department of Conservation and US Forest Service began educating folks and started fighting fires in order to suppress them.

Over time burning forests became a taboo. Now there are so many homes and infrastructure on the landscape that open burning is no longer safe for our culture as we have designed it.

Once the burn bans were implemented the forest grew too thick and crowded. The forestry professionals in Missouri then started advocating forest thinning as the strategy for tending forest health. Thinning is when a chainsaw is used to remove undesirable trees to increase spacing in order to deliver quality logs to sawmills. In many places this worked well and achieved good health. When I started my career in forestry in 2003 thinning was the primary management tool. It still is today with most professionals.

The thinning doesn't address ecology needs though. The plants that grow up after the thinning move the system further away from a balanced and resilient ecosystem. Each unique plant hosts unique bacteria compounding the biodiversity, and the losses that occur when a system loses biodiversity. The long term results of the thinning are becoming more evident as we watch more acres of thinned forest grow into maturity.

Controlled burning was used on a limited basis at the time. There were many of the 'old-school foresters' who grew in their careers suppressing fires. There were hostilities between the old-school foresters who didn't want to burn the forest and the younger foresters, and some of the future seeing old-schoolers, about burning woodlands and forests. I was witness to these hostilities in workshops, conference rooms, government offices, and in the field.

Today the standard seems to be to conduct forest thinning first in the restoration process. Then conduct burning, if at all.

When we thin an unmanaged and overstocked forest, the result is often that the understory and seedling layers of undesirable trees and shrubs grow to dominate the newly created open spaces. The overstory trees benefit from the thinning as their spacing improves, but the long-term consequences create a situation where many undesirables are growing up into the open spaces. The abundance and diversity of desirable native forbs, grasses, shrubs, ferns, and tree seedlings is generally low following the thinning. Thinning first can accelerate the conversion of an oak forest type into a non-oak forest type.

Before the first thinning we can conduct a few low intensity controlled burns. The first low intensity burn usually helps eliminate fire-intolerant tree seedlings, some small fire-intolerant shrubs, and some fire-intolerant forbs. A year or two later we conduct another mild intensity controlled burn and we further eliminate the fire-intolerants in those layers and bigger shrubs and tree saplings. The third mild intensity controlled burn a year or two later can further eliminate undesirables and some of the larger midstory trees.

After each burn we watch the results develop to decide when the next burn is needed. Schedules aren't as helpful as being present and observing. Burning two seasons in a row is ok if there has been good precipitation and growth.  If there has been a drought, burning is generally avoided two years in a row. Burning three years in a row can be too stressful.

After so many burns have been conducted the frequency can be lessened so more years pass between the burns. A decade or more can pass between burns once the initial burns have nurtured an understory of desirable diversity and abundance. The frequency of burning will largely be determined by goals, weather, and results of last burns.

Each burn has the potential to reduce sick and unhealthy trees from the overstory. The key is mild intensity burning that will stress vulnerable trees but do-no-harm to healthy trees. Research has shown that healthy trees can respond with greater growth rates the growing season following a mild-intensity burn. The last thing we want is a moderate or high intensity burn that damages and kills healthy trees. The fire reducing some of the sick and healthy trees, along with some of the fire-intolerant species, does some of the thinning without the need for a chainsaw.

With each burn, the leaf layer on the forest floor is reduced which leads to increased germination rates for seeds. Many native plants and trees have tiny seeds that once germinated, struggle to find the soil below the leaf litter. Even larger seeds like acorns have trouble surviving after germination when the leaf layer hasn't been reduced. Burning reduces the leaf litter and exposes the soil so seeds have contact with bare mineral soil, or a thinner leaf litter layer. Farmers till and disc fields for the same reason. Seed germination rates increase when seeds have contact with the soils.

With each burn, we see a flush of seed germination for many native plants, including the acorns of oaks. Many times after a burn we see a carpet of oak seedlings in a forest that previously had no oak seedlings. Oaks generally love fire. The reason we have a great oak forest is because the indigenous cultivated them through the use of fire. The oak forest is an inheritance and gift from those who tended the land. We can see that when fire is removed, the oaks are replaced with other species and the oak forest is converted to another dominant species, like maple, hackberry, or blackgum.

After the frequent low-intensity burns have cultivated desirable species on the forest floor, shrubs, tree seedlings, and understory trees, the first thinning can be conducted to improve spacing of overstory trees and provide sunlight to the cultivated crop of desirables below. After the lower layers have been tended to, the thinning releases them to fill in the newly created open spaces.

Slowly slowly we are returning to the wisdom of the people that managed this landscape for millennia. At first, the settlers went to one extreme by burning too hot and too often. Then people went to the other extreme of banning burning. We see both of these extremes have had devestating effects on forest and wildlife.

It is a pleasure to be alive in this time when we are restoring balance. We will continue to work out the nuances and the young professionals will further explore and discover. I'm not convinced the strategy I share is the best, nor do I think it is applicable on every site or situation.

I trust that the professionals will listen more to the indigenous people who still carry their traditions and are willing to share. Nuance is biodiversity. Thousands of years of management created a lot of nuance.

We've lost a tremendous amount of biodiversity and abundance since the first Europeans started trading and settling here. And then the big wave of Americans that came as the country moved west. Today in Brazil a similar story is unfolding with the frontier in the Amazon moving west. We can learn from all of this, integrate it into our lifestyle, cultural, and management decisions. We can be good stewards of this great biodiversity that was stewarded before.

I think most people see a forest and think that it's the same as it always was. Static and unchanging. That it will always restore itself to some natural static state. That is not how it works. It was managed by indigenous people to become the great forest that the first settlers witnessed and went to work on. It was managed by the settlers and all those that followed. We don't see many giant trees today because there are loggers and sawmills cutting trees down before they become giants. It is all managed today. We decide what management strategies are used.

Controlled burning is a major component to restoring our great oak forest and all the biodiversity it can contain. There is nuance and subletities in how we use fire to restore and manage ecosystems. Not all controlled burns are the same and rarely do they produce the same repeatable results.

We can continue to watch and learn, integrate and update our strategies. And to remember the ways of the people who maintained this landscape for millennia. Forest management requires multiple entries of cool burning for the site preparation of forest thinning.