Why Ecoregions Beat USDA Growing Zones in the Native Plant Game

Why Ecoregions Beat USDA Growing Zones in the Native Plant Game

by | Jul 27, 2025 | Ecology, Native Plants, Rewilding

What is an "Ecoregion" exactly?

Ecoregions are areas defined by shared environmental conditions: climate, geology, soil, water availability, and—crucially—plant and animal communities. They go way beyond temperature extremes, which is the only thing the USDA zones measure.

The EPA and other scientists classify these regions through a mix of satellite data, climate records, and field observations. Basically they ask “What ecological systems have the living world established here, and what makes them different or similar to the neighboring land conditions?”

The Layers of Specificity

There are 4 distinct levels of ecoregion classification that progressively divide the land into more and more specific areas of resources/climate/flora and fauna. Starting with Level I and ending with Level IV. There are other ways that the land is categorized on a smaller scale, but for this post, we’re just going to stick to these. 

Level I

The most Course Scale. Broad continental patterns. 15 total regions in North America. (e.g., Eastern Temperate Forests, Great Plains, Marine West Coast Forest.)

Level II

Intermediate Scale.  Subdivides Level I into 50 different regions.  (e.g. Southern Plains within the Eastern Temperate Forests.) 

Level III

Refines Level II further to show regional ecosystems. There are 182 Level III regions in North America. (e.g. Piedmont, Central California Valley.)

Level IV

The most detailed classification. Refining level III down to 967 different specific ecoregions in the U.S. Most valuable to the Native Gardener.  (e.g. Inner Piedmont, Northern Inner Piedmont (subregions within the Piedmont).

Ecoregions vs. USDA Zones : A Gardening Showdown

Let’s be real: USDA zones only tell you how cold it gets in winter and how hot it gets in summer.  On AVERAGE. That’s it. They don’t care if your soil is dry sand or sticky clay, or if your summers are soggy or arid.

Ecoregions, on the other hand, account for whole ecological systems – which means they’re vastly better at predicting what plants will not just survive, but thrive in a given space. There are such things as “Evolutionary Filters” that organisms have to pass through to establish a stable relationship with the surrounding flora and fauna. In some cases, this co-evolution has taken hundreds of thousands – even millions – of years. E.g., Monarch caterpillars need to eat milkweed to pupate. These evolved relationships are what construct functioning ecosystems from the ground up, and the introduction of organisms that don’t have them can have disastrous results. E.G. Chinese Pivet in American Woodland.

Why Scientists and Gardeners are Obsessed

For ecologists, ecoregions are crucial for studying biodiversity patterns, conservation strategies, and habitat restoration. Every relationship matters from the largest tree, to the smallest microbe.

For gardeners and landscapers, they’re like a cheat code for choosing plants that will not only thrive in the area, but also establish solid and stable plant communities that contribute areas of habitat to local ecosystems and increase biodiversity.

And for scientists, they help track the effects of climate change, pollution, the impact of human development, species movement, and land use over time.

Think of it like zooming in on Google Maps—from country to county to neighborhood

Why They Matter When Rewilding Your Yard

If you’ve made it this far, chances are you have already dipped your toe in the “Kill Your Lawn” movement. You have probably realized the damage our lawns and landscaping have done to the living world. So you want to bring back the bees, birds, and butterflies, huh? You need to speak the language of your land—and that means choosing native plants from your ecoregion. Plants from a different zone might look native-ish but won’t support the same insects, fungi, or ecosystem functions.

Rewilding works best when your yard becomes part of the surrounding natural matrix. Ecoregions tell you how to do that.

The Importance of Ecosystem Restoration Beyond Financial Value

I’ll go in depth in another blog, but for now….Just click the link below.  

Eco-Health Relationship Browser

5 Ways Native Plants Enhance Local Ecosystems

5 Ways Native Plants Enhance Local Ecosystems

by | Apr 3, 2025 | Native Plants

5 Ways Native Plants Enhance Local Ecosystems

Explore how native plants play a crucial role in supporting and revitalizing local ecosystems, offering sustainable solutions to environmental challenges.

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Let's start with the Basics

What is a Native Plant?

Native plants are species that have evolved in a particular region. Adapting, over thousand of years to the local climate, soil conditions, precipitation, herbivory, etc. They also have very specialized relationships with animals and insects of the area.

What is an Ecosystem?

An ecosystem is a community of living and non-living things that interact with each other in a specific environment. It includes plants, animals, microorganisms, soil, water, air, and sunlight, all working together to create a functioning system.

What is an Eco-Region

An ecoregion is an area of land or water containing a unique combination of natural features like climate, soil, vegetation, and wildlife. Defined by distinct geography, geology, and ecological characteristics that support specific flora and fauna.

1. Provide Food, Shelter and Habitat.

Native plants provide food, shelter, and habitat for local wildlife. Birds, bees, butterlies, beetles and yes, even flies have evolved relationships the native plants. Some insects have evolved symbiotic relationships with plants. In other words, if the plant dies out, the insect dies out.  Monarch butterflies(Danaus plexippus)are one of those. They require the Milkweed (Asclepias) plant to reproduce. Their caterpillars can ONLY eat the milkweed plant. Other pollinators use the stems of some native plants to over-winter within. Oak trees(Quercus) are ecological powerhouses, supporting over 400 species of insects.

2. Reduces Invasive Species

Every bit of space taken up by a Native Plant takes that space away from possible destructive and invasive plants.  Unfortunately it works both ways. There are things called “Evolutionary Filters” that control populations and help maintain ecological equilibrium. Whether it be bugs or animals that eat them, competition with specific other species, or even pathogens that keep them balance. Non-native plants can outcompete native species for resources because they don’t have these “checks and balances” with often times leads to a decline in local biodiversity. By using native plants, you can reduce the risk of invasive species taking over and restore a bit of that natural balance.

3. Water Conservation

This one is a little more tenuous a claim. A lot depends on the ecosystem and the plants being referenced. If you’re planting prairie plants MANY of them are deep rooted, which leads to more drought tolerance. Some wetland plants would be the opposite, and completely contrary to that claim. Many forest plants tend to create a large carpet of roots. It’s important to acknowledge these differences. However, ALL native plants are adapted to their own local climate conditions. If you’re referring to grassland plants, then yes these plants TEND to require less irrigation compared to non-native species. Their deep-root systems allow them to access water from deeper soil layers, reducing the need for supplemental watering. It’s imperative to understanding these difference when creating functioning plant communities.

4. Reduced Need for Pesticide and Chemical Fertilizers

Since plants that are native to your region evolved to thrive in your local ecosystem; that usually means they are less susceptible to pests and diseases, because they tend to grow better and be healthier. This reduces the need for pesticides and fertilizers, which can harm local wildlife, contaminate soil, and pollute water ways. Native plants also play a crucial role in maintaining soil health. Most people don’t consider that even the roots create habitat for native fungus, bacteria, and other microscopic helpers, all of which are killed or damaged by pesticide/herbicide use. By choosing native plants, we can create resilient ecosystems that thrive without chemical intervention, creating a net positive for the world and saving you money on the “Lawn Management” scam.

5. Enhancing Ecosystem Services

Native plants do so much for local-ecosystems: Soil stabilization, carbon sequestration, and in a broader scale, climate regulation. Before the Great Plains were destroyed by agriculture, there were very few natural lakes (exactly 0 in Oklahoma). The open prairie held all of the water it needed to sustain itself. The density of the plants and richness of the soil built over millennia  regulated the weather. This tightly packed network of plants provided food, shelter, breeding grounds. It filtered water, cleaned the air and regulated ground temperature and humidity. Ecosystems have become so fragmented that even a single native plant helps provide a springboard for the living world in the vast, dead, concrete deserts we’ve created.

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