Why is Central Oregon So Biodiverse?

As gardeners, landscapers and owners of a native plant nursery for over 30 years, we’ve had our fair share of interesting, sometime humorous, but never stupid questions. One common theme is the difficulty of growing ANYTHING in our challenging area, but more specifically, what CAN we grow in our wonderful soils and climate. Our answer is always “native plants!” There are hundreds of native plants that grow well in gardens and landscapes, but most never reach the commercial market. Getting started with native plant landscapes is a bit easier with a general understanding of plants, where and why they occur and the conditions in which they thrive. And along with that, an awareness of the incredible diversity of plants native to central and eastern Oregon is essential.

Many newcomers to central Oregon love the climate and the outstanding recreational opportunities available, but have limited knowledge of the amazing diversity of plants and animals that occur east of the Cascades. And it really is amazing! Driving through the sagebrush steppe east of Bend looks desolate and boring, but the richness of the plant community is difficult to see at 65 miles per hour. And the subtle changes in plant communities often go unnoticed.

Compared to the Willamette Valley — often thought of as a highly diverse region — central and eastern Oregon contain about four times the number of native plants (~ 350-500 in the valley; ~2,000 in central and eastern Oregon, according to Oregon Native Seed Strategy. But why?

Condensing a long discussion into a brief summary comes down to three primary reasons: topography, microclimates and ecotones. There are, of course, a number of variables that affect each of these drivers at different scales, but the basic reason there are so many different plant species is that there are so many different environments east of the Cascades.

For example, Hells Canyon on the Oregon-Idaho border drops to an approximately 1,000 ft. elevation, capturing heat in the deepest gorge in North America and creating unique thermal conditions that support specific types of plants. Contrasting those plants with the flora at the top of Steens Mountain (approximately 9,700 feet) shows how a huge variation in elevation and climate affects what kind of plants live where. Then quickly dropping east off Steens Mountain to the Alvord Desert — a drop of over 5,000 vertical feet — reveals many different plant communities from alpine to alkali flats in a very short distance. Incredible!

The Steens Mountains in southeast Oregon host a wide plant diversity. Credit: Rick Martinson

The different environmental conditions that occur in small areas on this side of the state, generally referred to as microclimates, reflect specific soil, precipitation patterns, geography and geology, and play a huge role in supporting the plant diversity in central and eastern Oregon. There are plants that are adapted to “islands” of unique soil chemistry, or that have evolved with our nutrient poor soils or highly variable rain and snow patterns or specific amounts of sun or shade. The variation in microclimates has an enormous effect on the diversity of plants growing in even very small areas and contributes to the amazing biodiversity throughout the region.

The third primary reason for the high degree of diversity in our part of the world is ecotones. Ecotones are areas where two or more large environments merge together. Those ecotones contain plants and animals that are characteristic of each of those larger environments, but may also contain species that are unique to those blended conditions. I hope that makes sense. For example, the west side of Bend is predominantly a ponderosa pine forest, while the east side of the city is characterized by western juniper. Where those two major plant types come together forms an ecotone that supports not only plants that occur in both plant communities, but also some unique plants and a suite of insects, birds and mammals that occur only in the distinctive conditions found within that ecotone.

A highly diverse plant community in Sheldon National Wildlife Refuge on the Oregon-Nevada border. Credit: Rick Martinson

So next time you’re traveling through the east side of Oregon, stop and check out different areas that offer examples of microclimates, ecotones or unusual topography. Each location will have a range of plants, insects, and animals that are well adapted to the conditions found there. Those types of areas show exactly why the biodiversity of central Oregon is so profound. And you might discover your next favorite plant that you can incorporate into your own garden!

Rick Martinson is the founder of the High Desert Horticultural Center, a Bend-based nonprofit working to increase the understanding and appreciation of native plants and their contribution to resource conservation in urban landscapes. Contact them at www.highdeserthort.org, or Rick@highdeserthort.org.

This article appears in the Source August 6, 2026.