What is the 10 20 30 rule for tree planting in Green Bay?

The 10-20-30 rule for tree planting in Green Bay is a crucial guideline for urban forestry that tree companies and city planners often follow, recommending a community's tree population consist of no more than 10% of any single species, 20% of any single genus, and 30% of any single family. This proactive strategy promotes biodiversity and resilience, directly shaped by the devastating local impact of the Emerald Ash Borer.

The Ghost of Canopies Past: Green Bay's Painful Lesson in Monoculture

For anyone who has lived in Green Bay for more than a couple of decades, the memory of our former streetscapes is a vivid one. Neighborhoods from Astor Park to Allouez were once graced by majestic, vase-shaped canopies of American Elm (*Ulmus americana*). They formed green tunnels over our streets, a defining feature of our city's character. Then, Dutch Elm Disease swept through in the mid-20th century, a relentless plague that left behind skeletal remains and sun-scorched avenues. It was our first, brutal lesson in the danger of loving one type of tree too much.

In the aftermath, a well-intentioned replanting effort began across Green Bay and all of Brown County. Seeking a fast-growing, hardy, and aesthetically pleasing replacement, city planners and homeowners alike turned to another tree: the ash. Green, White, and Black Ash trees from the *Fraxinus* genus quickly filled the void left by the elms. They were beautiful, tough, and seemed like the perfect solution. For a generation, they were. Streets were once again lined with a uniform, handsome canopy. But in our haste to heal the landscape, we repeated the same mistake.

We created a new monoculture. The historical over-planting of specific tree species, such as ash trees to replace elms lost to Dutch elm disease, created monocultures in many urban areas, which proved catastrophically vulnerable to subsequent pest infestations like the Emerald Ash Borer. This wasn't a hypothetical risk; it was a ticking time bomb nestled in the bark of nearly every fourth or fifth tree in our community.

When the Emerald Ash Borer (EAB), a small but devastating beetle, arrived in Wisconsin, that bomb detonated. The result was an ecological and financial catastrophe for Green Bay. We watched as tens of thousands of ash trees, part of the Oleaceae family, succumbed. The cost of Tree Pest Management was astronomical, but the cost of removal, stump grinding, and replanting was staggering. More than just a line item in the city budget, it was a loss of shade, a blow to property values, and a quiet hollowing-out of our urban forest. This recent, painful memory is the crucible in which Green Bay's commitment to a new way of thinking was forged. It’s the reason the 10-20-30 rule isn't just arboriculture jargon here; it's a solemn promise to never let that happen again.

Defining the 10-20-30 Rule: A Blueprint for a Resilient Urban Forest

So, what is the 10 20 30 tree rule, exactly? It’s a simple yet powerful guideline for ensuring biodiversity in an urban tree canopy. It serves as a core principle for modern community forestry and is the bedrock of our local strategy for Climate Change Resilience and Invasive Species Management. At its heart, the rule is a mathematical defense against catastrophic loss.

A widely accepted guideline for tree diversity in a municipal forest is to plant no more than 10% of any one species, 20% of any one genus, and 30% of any one family. Let's break down what each of those levels means for a homeowner or property manager in Green Bay.

• 10% Species Diversity: This is the most specific level. It means that out of all the trees on your property or in your neighborhood, no more than 10% should be of a single species. For example, if you have 10 trees, only one should be a 'Red Sunset' Maple. This prevents a disease or pest that targets a very specific tree from wiping out your entire canopy.
• 20% Genus Diversity: This is the next level up in the biological classification. A genus is a group of related species. The popular *Acer* (Maple Genus) includes Sugar Maple, Red Maple, Silver Maple, and numerous others. The rule dictates that all maples combined should not make up more than 20% of your total tree population. This is critical because many pests, like the Asian Longhorned Beetle, target an entire genus.
• 30% Family Diversity: This is the broadest category. A family is a group of related genera. For example, the Fagaceae (Oak Family) includes the *Quercus* (Oak Genus) as well as beeches and chestnuts. The Sapindaceae family includes the Maple genus. This rule provides a firewall against pests or diseases that can jump between related genera within the same family.

Think of it like a diversified investment portfolio. You wouldn't put all your money into a single stock. Likewise, we shouldn't invest all of our green infrastructure into a single type of tree. Some municipalities and forestry experts even advocate for a stricter guideline, sometimes called the 20 10 5 rule for forestry, which limits a single family to 20%, a genus to 10%, and a species to 5%. While more aggressive, it's based on the same principle: in diversity, there is strength.

From Reaction to Proaction: How Green Bay Implements Urban Forest Diversity

The lessons from the Emerald Ash Borer epidemic have fundamentally changed the practice of arboriculture in our city. The City of Green Bay's Parks, Recreation & Forestry Department has shifted from a reactive stance—dealing with crises as they come—to a proactive strategy rooted in the principles of biodiversity. The 10-20-30 rule is no longer an abstract concept; it's an active management tool.

A key component of this strategy is the city's comprehensive Street Tree Inventory. By cataloging and mapping every public tree, the City Forester can get a real-time snapshot of our urban forest's composition. This data reveals where we are overly reliant on certain species, like the still-popular maples, and guides decisions for future plantings. When a tree is removed, the inventory helps determine a suitable, diverse replacement that strengthens the overall canopy rather than repeating old patterns.

This proactive approach extends to new developments as well. The city's Municipal Tree Ordinance and Tree Selection Guidelines now incorporate diversity metrics. Before a developer can get a Tree Permit for a new commercial property or residential subdivision, their landscaping plan is reviewed to ensure it contributes positively to the city's biodiversity goals. This prevents the creation of new monocultures and ensures that our urban forest grows stronger and more resilient with each new project.

This work is part of a larger movement towards Sustainable Landscaping and the development of Green Infrastructure. The Wisconsin Department of Natural Resources (DNR) supports these community forestry efforts, recognizing that a diverse and healthy tree canopy is essential for everything from Stormwater Management to improving air quality.

A Deeper Look: Comparing Strategies for a Healthy Green Bay Canopy

Understanding the "why" behind tree diversity requires comparing the guiding principles at play. For homeowners and property managers, choosing the right approach impacts long-term costs, maintenance, and the overall health of your landscape.

The 10-20-30 Rule as a Guideline

Pros: It provides a simple, clear, and actionable framework that anyone can understand and apply. It's an excellent starting point that effectively prevents the most egregious errors of over-planting. For a homeowner looking at their yard, it's an easy-to-remember rule of thumb for making smarter choices.

‍

Cons: The rule can be overly simplistic in complex ecosystems. It doesn't inherently account for site-specific conditions, such as a need for Salt Tolerant Trees along a heavily salted road, or the specific Soil Type and Health of a property. It's a guideline, not an unbreakable law, and must be applied with common sense and local expertise.

Urban Forest Resiliency as a Strategy

Pros: This is a more holistic and robust approach. It encompasses the 10-20-30 rule but goes further, considering factors like age diversity (having young, mature, and old trees), climate change adaptability, and creating a robust ecosystem that supports Wildlife Habitat. It's a long-term strategy for a thriving urban environment.

‍

Cons: Implementing a full resiliency strategy is far more complex and data-intensive. It requires deep knowledge of arboriculture, ongoing monitoring through a Street Tree Inventory, and significant long-term planning. For a single property owner, it can feel overwhelming without professional guidance.

Monoculture Vulnerability to Pests

Pros: From a purely initial, short-sighted perspective, planting a monoculture can seem appealing. The trees are uniform in appearance, growth rate, and maintenance needs, which simplifies purchasing and initial care. This is why it became so common in post-war housing developments.

‍

Cons: The risks are catastrophic and, as Green Bay learned firsthand, almost inevitable. A monoculture is a single point of failure. When a pest like EAB or a disease like Dutch Elm Disease or Oak Wilt arrives, the potential for 100% loss is very real. This leads to immense removal costs, drastic loss of property value, and the sudden disappearance of all associated environmental benefits like shade and energy savings. A monoculture is not an asset; it is a significant liability.

Key Factors for Your Green Bay Planting Project

When you decide to plant a tree on your property in Green Bay, you're making a long-term investment. Applying the lessons of urban forest diversity to your decision-making process will ensure that investment pays dividends for decades to come.

Long-term tree health and survival

The single most important principle for tree health is "Right Tree, Right Place." Before you even think about species, a proper Site Assessment is crucial. In much of Brown County, we contend with heavy clay soil, which affects drainage and root growth. You must consider our USDA Plant Hardiness Zone 5b climate, with its cold winters and variable summers. Is the spot sunny or shady? Is it near power lines? Answering these questions first ensures the tree you choose has a fighting chance to thrive, preventing costly and heartbreaking replacements down the line.

Species diversity and selection

This is where the 10-20-30 rule comes directly into play. Look around your yard and your immediate neighbors' yards. Do you see a sea of maples? Then planting another Autumn Blaze, despite its beauty, is not a resilient choice. Choosing from a list of underutilized Native Wisconsin Trees or well-adapted non-natives adds strength to the entire neighborhood canopy. Diversity isn't just a defense; it also creates a more interesting, year-round landscape and provides varied food and shelter for local wildlife.

Cost of proactive planting vs. reactive mass removal

The financial argument for diversity is undeniable. The cost to purchase and properly plant a single, high-quality tree might be a few hundred dollars. The cost to have a large, dead, hazardous ash tree professionally removed from near your home can be several thousand dollars. Multiply that by the thousands of trees lost in Green Bay, and the economic lesson is clear. Investing a little more time and thought into a proactive, diverse planting strategy now is an insurance policy against the massive, reactive expense of mass removal later.

Property value preservation

A lush, healthy, and mature tree canopy is consistently shown to increase residential property values. A diverse collection of trees is a stable, appreciating asset. A monoculture of ash trees, as many discovered, can become a multi-thousand-dollar liability overnight, dragging down the value of your property. By planting with diversity in mind, you are not just beautifying your yard; you are protecting and enhancing its long-term market value.

Your Yard is Part of the Solution: Building a Diverse Canopy, One Tree at a Time

The resilience of Green Bay's urban forest doesn't just depend on the City Forester. It's a collective effort, and private property owners play a massive role. Your yard is a vital piece of our community's Green Infrastructure. You can contribute directly to our city's health and beauty by applying the 10-20-30 rule to your own property.

Here is a simple framework to perform a basic Site Assessment and diversity check:

1. Identify and Count: Walk around your property and identify the trees you have. If you're unsure, there are many excellent tree identification apps or guidebooks available from the University of Wisconsin-Extension. Tally them up by species (e.g., 2 Silver Maples, 1 River Birch) and then by genus (e.g., 2 *Acer*, 1 *Betula*).
2. Look Next Door: Peer over the fence. Your trees don't exist in a vacuum. If your neighbor has three large maple trees, you should factor that into your calculation. The goal is neighborhood-level diversity.
3. Plan for the Future: When it's time to plant a new tree, use your inventory as a guide. If your yard is already heavy on the *Acer* (Maple Genus), it's time to explore other options. This simple act of strategic Cultivar Selection makes a huge difference.

Beyond the Usual Suspects: Underutilized Trees That Thrive in Green Bay

One of the biggest challenges in promoting diversity is breaking free from old habits. Many people plant what they know—maples, oaks, and lindens. While these are wonderful trees, their overuse can create the next monoculture problem. Here are some fantastic, tough, and beautiful trees that are under-planted in our area and deserve a place in our landscape.

Tried and True (But Don't Overdo It)

Trees from the *Quercus* (Oak Genus), *Acer* (Maple Genus), and *Tilia* (Linden/Basswood Genus) are staples for a reason. They are generally well-adapted to our region. However, they are often the most heavily planted. If you choose one of these, select a less common species or cultivar and ensure it doesn't push your property over the 20% genus limit.

Excellent, Underplanted Choices for Brown County

• Celtis occidentalis (Common Hackberry): Perhaps the toughest urban tree you can plant. It's highly tolerant of our clay soils, drought, and street salt. It features unique, corky bark and produces small berries that are a favorite of birds.
• Kentucky Coffeetree (*Gymnocladus dioicus*): This native tree has a striking, rugged appearance in winter and large, tropical-looking leaves in summer. It's very adaptable and has no serious pest problems. A male, seedless cultivar is often preferred for yard settings.
• Swamp White Oak (*Quercus bicolor*): While it's an oak, it's one of the most underutilized. It is far more tolerant of the compacted, poorly-drained clay soil common in Green Bay than many other oaks. It's a fantastic and long-lived shade tree.
• Ironwood (*Ostrya virginiana*): A smaller, slow-growing native tree that is perfect for smaller yards or as an understory tree beneath larger ones. It has beautiful, hop-like seed pods and a high tolerance for shade and tough conditions.

Resources for Local Expertise

For more ideas and to see mature examples of these trees, a visit to the Green Bay Botanical Garden is an invaluable resource. Additionally, the local office of the University of Wisconsin-Extension is a wellspring of research-based information on Native Wisconsin Trees and other species well-suited for our specific conditions.

Common Questions About Tree Planting in Northeast Wisconsin

Making the decision to plant a tree often comes with a few practical questions. Here are answers to some common queries we hear from residents in the Green Bay area.

Is October too late to plant a tree in Green Bay?

Absolutely not. In fact, autumn is often considered the ideal planting season in our climate. Planting a tree in late September or October allows the root system to become established during the cool, moist fall months without the heat stress of summer. The tree can focus all its energy on root growth instead of producing leaves. The general window for fall planting is from late August until the ground freezes, which is typically in early to mid-November here. A proper Tree Watering Schedule is still crucial until the ground is frozen.

Why does Bill Gates say "don't plant trees"?

This is a common misinterpretation of a more nuanced point. Bill Gates has never advocated against planting trees in general. His commentary was specifically about the idea that simply planting a few trees is a silver-bullet solution for climate change. His argument is that for meaningful Carbon Sequestration, the focus should be on protecting existing old-growth forests and undertaking massive, strategic reforestation projects, which are far more effective at scale than individual yard trees. For us here in Green Bay, our primary goals for tree planting are different but equally vital: increasing biodiversity, managing stormwater, creating a resilient canopy, reducing the Urban Heat Island Effect, and improving quality of life. Our strategic planting contributes to a healthy local environment, which is a critical piece of the larger climate puzzle.

What are the basics of proper tree planting?

Proper planting technique is essential for long-term survival. Key Tree Planting Specifications include digging the hole two to three times wider than the root mass, but no deeper. The spot where the trunk flares out to meet the roots should sit at or slightly above ground level. When dealing with Container Grown Trees, be sure to cut any circling or Girdling Roots. For Ball and Burlap Trees, remove all twine and at least the top half of the wire basket. With Bare Root Trees, ensure the roots don't dry out before planting. After placing the tree, backfill with the native soil, avoiding Soil Compaction, and water thoroughly. Finally, apply a 2-3 inch layer of Mulching, keeping it away from the trunk itself to prevent rot.

Making the Right Choice for Your Needs

The principles of tree diversity and resilience are universal, but how you apply them depends on your specific role and goals. The best strategy is one tailored to your situation.

For the Municipal Urban Forester

Your responsibility is the entire community's canopy. The 10-20-30 rule should be the foundational metric guiding your Tree Planting Specifications for parks, public spaces, and streetscapes. Your focus must be on large-scale data analysis using your Street Tree Inventory, long-term planning for Climate Change Resilience (e.g., exploring assisted migration of species from more southerly zones), and extensive public education to get homeowners on board. You are the chief advocate and strategist for the city's green assets.

For the Proactive Homeowner

You may have personally experienced the cost and loss from the Emerald Ash Borer. Your goal is to never repeat that. View your yard not as an island, but as a crucial part of your neighborhood's ecosystem. Your primary tool is smart Species Diversity. When you plant a new tree, make a conscious choice to select an underutilized species. A Kentucky Coffeetree or Hackberry may be less familiar than a maple, but it's a far more powerful choice for building a resilient landscape. Your investment protects your property and strengthens your entire community.

For the Commercial Property Manager

Your decisions are driven by budget, safety, aesthetic value, and liability. Monocultures represent a massive financial risk. A diverse landscape is a managed risk. Planting a variety of species, including Drought Tolerant Species to reduce watering costs and Salt Tolerant Trees near parking lots and sidewalks, lowers long-term maintenance and replacement expenditures. A healthy, varied, and beautiful landscape enhances curb appeal, increases property value, and contributes to tenant and customer satisfaction. It's a smart business decision that aligns with ecological responsibility.

Ultimately, creating a strong, resilient, and beautiful urban forest in Green Bay is a shared responsibility. The lessons of the past have shown us the peril of uniformity and the strength found in diversity. By making informed, strategic choices—whether on a city block or in a single backyard—we can cultivate a canopy that will thrive for generations. For a professional Site Assessment, expert tree selection advice tailored to your property, and planting services that ensure long-term health, contact our family-owned team at Hardy Wood Products today.