THE CARE AND PROTECTION OF BIG & IMPORTANT TREES

Tree preservation is an old practice – people have recognized the importance of individual, remarkable trees for millennia. There are several considerations for preparing to protect a large or historic tree, and all physical work should be completed with the assistance (or under the direction) of an ISA-certified arborist.

There are two main ways to protect an important tree: cultural and physical. If a tree is not culturally protected, even if it is physically supported it is at risk of removal by people who do not understand how important the tree is. If it is not physically protected, there is no amount of cultural protection that can keep gravity, lightning, rot, and high winds from ending the life of the tree.

CULTURAL PROTECTION

National Champion Trees are, in general, not legally protected from damage or removal unless specifically protected by a local ordinance.

Local ordinances are a great way to start protecting important trees in your area. First, you’ll have to identify who makes these decisions – it’s usually a city council, a county board of supervisors, a prefecture’s assembly, or a parish council.

Usually, their meetings are open to the public and you can submit something for consideration or bring up a topic during the meeting. Rules about this vary from place to place, so make sure you find out what your local procedures are.

To prepare for this, do some research on the importance of trees (or this specific tree) to your community. Do people know this tree? Is there historical documentation showing that it was living during important events in your town’s history? Has it been designated as a Local, State, or National Champion Tree?

One extremely effective way to protect a tree is to give the tree a name! It’s not very interesting to protect another “Southern Red Oak”, but it can be very meaningful to protect the locally-beloved “Grandmother Oak”.

It also helps to do some research on how other similarly-sized cities/towns/counties have written their Tree Protection Ordinances.

Once you speak to your area’s decision-makers about putting together an ordinance to protect trees, continue to build community support for the idea. Some effective ways to build support are:

• Hosting events under/near the important tree
  • Poetry readings, local musicians, reading books to children, having a picnic/cookout, hosting an art class or workshop, even creating a festival!
  • The goal is “placemaking” – transforming an area from a ‘space’ to a ‘place’ by building connections between people and the space. When we use a space for storytelling, sharing values and experiences, or creating relationships with our community, it makes the space more “legible” or understandable to the people who are there.
    • Another similar idea is “meaning-making” – when people think about your tree, we want them to remember what a good time they had there and all the wonderful people they were with! Sometimes, negative meaning-making can happen – when we have a bad experience in a place, we’re less likely to go back there or to protect it. We protect the things and the places we care about. Making positive meaning in a space can change it from a spot that nobody cares about to a place that people love.
• Sharing the story of the tree
  • Reach out to local news with the story of your tree!
    • Giving it a name really helps with this part – a tree in danger of getting cut down isn’t news, but if someone wanted to cut down “The Angel Oak” in South Carolina, it would be huge news. That tree is beloved, easily recognizable, and has been featured in books and television ads!
  • Post about the tree on social media and see if local organizations will post about it too.
    • Spread the word with beautiful pictures and personal stories – way more impactful than general facts about trees. Numbers are interesting, but people are truly moved by a good story.
  • Work together!
    • A single drop of water is a nuisance, but a whole bunch of water can carve through mountains and lift up cars. Build connections in your local community to amplify your message.
• Create art about the tree
  • This ties into meaning-making – the more culturally important your tree is, the harder it is for other people to remove or harm it.

With tenacity, courage, teamwork, and creativity, you can help protect important trees for our grandchildren’s grandchildren to enjoy!

PHYSICAL PROTECTION

There are many new and old technologies to help physically protect trees: bracing, cabling, lightning rods, and (maybe the most important) protecting the critical root zone. These methods should be done in conjunction with an ISA certified arborist – without their expertise and insurance, you might be opening yourself up to liability lawsuits and a huge legal headache!

1. Cabling and Bracing:

a. Cabling helps to hold trees upright, to keep them from splitting, or to support a heavy limb. A strong metal cable is screwed into or threaded through the limb/trunk in question and the other end is attached either to another sturdier part of the tree, to other trees nearby, or to an anchor in the ground. Dynamic cabling systems may be wrapped around the limb or trunk and are designed to expand as the tree grows to give more flexibility and natural movement than a rigid cabling system. Typically, canopy anchoring by cable occurs in the top third of the crown above the fork and requires skilled climbers to install.

b. Bracing is used to prevent “crotches” or forks in the tree from splitting further, and to prevent cavities from further weakening the entire structure of the tree. There are a few different types – some are long, metal bolts, rods, or pipes threaded through both halves of the tree/branch and secured on either side. Some braces do not run through the tree but instead act to support a limb or stem from the outside.

Installed cables and braces should be regularly inspected to ensure that they have not failed.

These methods are usually last resorts, attempted only after other methods have been considered and tried/failed or rejected. Sometimes, pruning and removing large branches or codominant stems can reduce the amount of weight pulling on and splitting the tree, or can reduce the effect of wind blowing through the canopy like the sail of a ship. Removing limbs and stems can also negatively impact the aesthetic of the tree, or the health of the tree, but should be considered before moving to cabling and bracing.

2. Construction Damage:

Some of the greatest dangers to trees in the urban environment (and during this time of urban sprawl) are construction/development. It is nearly impossible for trees to recover from construction damage – the only way to ensure the survival and health of the trees on a construction site are to prevent the damage from occurring in the first place.

With attempting to prevent construction damage to trees, we are primarily concerned with soil compaction and contaminants, altering the pH of the soil, and harming the tree directly through contact with people and machinery. The damage done by construction often does not appear for many years – trees store a great amount of resources in their woody structures. Once that stored energy is depleted, the tree will rapidly decline.

Damages within the Critical Root Zone are especially harmful to the health of the tree.

Creating a Tree Protection Zone is an effective way to protect the trunk and critical roots of a tree.

There should be a physical barrier around the TPZ that cannot be easily moved, and it should be clearly communicated through signage (in multiple languages, with respect to the native languages of people working and visiting the site) and safety meetings what behaviors are prohibited in this area. If it is a barrier that is easily crossed or moved, people will almost certainly do so.

Prohibited behaviors may include but are not limited to stockpiling materials or debris, parking vehicles or equipment, piling soil or mulch, trenching for utilities or irrigation system installation/repair, driving or walking over the area (compacting soil), changing soil grade, installing impervious surfaces, attaching anything to the tree itself, wounding the trunk with equipment, breaking stems or branches through contact with vehicles or heavy equipment.

Often, we are required to perform work that requires digging around the tree. It’s important to pay attention to the distance from the trunk to ensure that the tree is better able to compartmentalize the damage without endangering its own stability.

Linear trenching should be (at a minimum) 3 times the trunk diameter away from the trunk, 5 times is preferred. Cutting roots at a distance 6 times the trunk diameter minimizes the impact on tree health and stability. When digging and trenching where tree roots are present, roots greater than 3 inches in diameter should be preserved – those are structural and vital for the stability of the tree during weather events. The best methodology is to use an air spade to blast away the soil around the root system and then thread the utility lines beneath the root system. This is more time consuming than simply trenching and chopping the roots as you dig, but it has a significant and positive impact on the long-term health of the tree, saving on future costs for tree/soil remediation and tree removal (and, worst case scenario, the death or injury of a person due to the failure of the tree.)

The TPZ on a construction site often requires consistent enforcement from the people responsible for the site, and the work of protecting these trees doesn’t stop after the construction is finished. Trees protected during construction should be monitored for signs of stress or pest activity for around 5 years, and they should not receive supplemental nutrition for the first year after the construction is done.

When a human is sick, we often prescribe rest, fluids, and nutritious food like chicken noodle soup – the goal is to create the best possible environment for healing, and to ensure that the person’s basic needs are met so their immune system can function at its best. The same goes for trees! By employing good plant healthcare practices during that 5-year monitoring period, we’re giving these trees the opportunity to recover from the shock and disruption of construction.

3. Other notable ways to physically protect trees:

a. Lightning protection systems

A large, old tree is often one of the prime targets for lightning strikes in a landscape. The tree’s species, height, spatial relationship to buildings and pathways, and cultural value all contribute to deciding which trees should be prioritized for this type of protection. Some tree species are more likely than other species to suffer significant harm from a lightning strike – this depends on both their internal moisture content and the climactic differences across regions.

This system requires an arborist with specialized training. The arborist climbs to the top of the tree or uses a mechanical lift to reach the top – the conductor cable should be attached as high as possible to attract the lightning bolt to it. The conductor cable is then secured to the tree’s branches and fed down the side of the trunk. A trench is dug from the base of the tree out past the crown, a minimum of ten feet from the trunk. The cable is installed in that trench and at the edge of the trench farthest from the trunk, it is attached to a grounding rod that is driven to a depth of 8 feet into the ground. These grounding rods should be placed well away from other structures, especially houses. Some soils are too shallow for an 8-foot-deep rod, so adjustments may be made depending on the site’s characteristics.

Large-crowned trees may require multiple conductor cables to fully protect the tree. These cables should be installed at the highest points in the crown and then spliced together at the stem to run down the trunk.  

These systems require frequent inspections in order to do their job well – damaged components must be replaced, and the system must be secured to the tree. The ANSI (American National Standards Institute) provides guidelines for lightning protection systems in the ANSI A300 (Part 4).

b. Landscaping

Trees can be socially, culturally, and physically protected through thoughtful and conscientious landscaping.

The most common tree protection landscaping is a simple circle of mulch around the base of the tree (not in a “mulch volcano” but spread evenly with the root flare at the base of the trunk clearly visible above-ground). A large circle of mulch and a small decorative landscaping fence can create a visual cue that this area is not for walking or piling materials. This mulch circle should extend to (at a minimum) the dripline of the tree, or the outermost edge of the crown, but for true protection should extend to cover the full CRZ which may be significantly larger based on the age, health, and size of the tree.

Additionally, shade-loving plants can further protect the area underneath the tree, providing even more incentive to stay off the roots – plants like hostas, ferns, and geraniums all have shallow roots and thrive under the dappled light of a large shade tree.

A boardwalk constructed to lead visitors to the tree and allow them to walk around the tree can also mitigate the compaction caused by people walking over the CRZ. The lifted walkway protects delicate plants and soil beneath the boardwalk and off the path nearby, and can be an attractive architectural feature to highlight the importance and value of the tree.

Lighting the tree at night can help to reduce vandalism and make it clear that the space is attended by people who care for the tree, but light pollution can negatively affect the other organisms that rely on the tree for habitat so features like this should be used only after thoughtful consideration. Signage, art, and small monuments/sculptures can help make meaning in the space, as well as provide much-needed interpretation. For people who aren’t “tree people”, it’s easy to overlook trees as part of the haze of background greenery happening behind our vibrant human lives. With informative communication and art that resonates with people beyond words, we can create physically and culturally protected zones to ensure that our magnificent trees live for many generations to come.