Nebraska is unique, lying at sort of a biological crossroads between the southern and northern plains, eastern deciduous forest and western Rocky Mountain species.
As a result, many of our native tree species are at the fringes of their natural range in terms of rainfall and temperature extremes, meaning that Nebraska may be able to offer a unique range of hardiness and adaptability for a shifting climate.
A few trees from local seed source that are being propagated and promoted include:
Dwarf chinkapin oak. In the far southeast corner of Nebraska grows a unique population of dwarf chinkapin oaks. Preserving this species’ native habitat is essential because it is dwindling in much of its native range. It is listed as imperiled in eight states and vulnerable in five more. This unique, small specimen tree works well in the landscape or in wildlife plantings and shelterbelts so it is worth protecting and propagating.
Paper birch. The natural range of the paper birch extends from Canada south to the far northern edge of Nebraska, in the Niobrara River valley. Paper birch are known for their snow-white exfoliating bark, dark green foliage and excellent golden-yellow fall color. We’re finding that trees grown from native Nebraska seed source are performing well beyond their normal range.
Rocky Mountain birch. Another birch that deserves to be planted more is Rocky Mountain birch, a western species that grows naturally along streams in canyons throughout the Rockies and is native to the northwestern corner of the state. There is a small native population in Sioux County, growing along Monroe Creek in Sow Belly Canyon. This large, multi-stemmed shrub grows 15- to 20-feet high and 15-feet wide and has attractive cherry-like bark and coarsely toothed leaves that turn golden yellow in fall. The Sow Belly™ Birch appears to have great potential for the future.
Hackberry. Though not always a “preferred” species in some areas, hackberries can handle tough conditions in both rural and urban areas. In Nebraska, it grows on the fringes of its natural range in a small spring-fed canyon near Sidney called Lehman Springs. This is an area surrounded for miles by treeless shortgrass prairie. The cool waters of a spring-fed creek have supported a grove of hackberry trees there that has been carbon-dated back 18,000 years based on fossilized seeds. The Nebraska Statewide Arboretum is currently growing seedlings for distribution and testing trees from this seed source, which we think may be an adaptable, leather-tough tree for the future.
Quaking aspen. Here in Nebraska we have isolated pockets of native quaking aspen trees, leftovers from glacial times and a colder climate. One small isolated pocket was originally found growing in a pasture in east-central Nebraska. Trademarked as Prairie Gold™ quaking aspen, it was introduced into the nursery trade by several growers nearly a decade ago and is growing well not only in Nebraska, but also in Kansas and Oklahoma, where it had not been grown previously.
The importance of growing local and native is becoming increasingly clear. Landscapes with a strong sense of place benefit individuals, communities, pollinators and other wildlife. They may also offer the best chance for sustainability in a changing and variable climate.
Bob Henrickson is horticulture program coordinator for the Nebraska Statewide Arboretum. Read more at plantnebraska.org.