Photo: Sagebrush habitat with bison, Yellowstone National Park. © 2016 Delena Norris-Tull
Revegetation with Native Plants to restore disturbed sites
Summaries of the research and commentary by Dr. Delena Norris-Tull, Professor Emerita of Science Education, University of Montana Western, September 2020.
Over the past few decades, more and more States and Federal Agencies have come to recognize the importance of revegetating disturbed lands with native plant species. And more and more programs have been developed, to conduct research on, or to grow and produce native plants and native seed, for use in landscaping and revegetation. Here are a few of those programs.
Native Plant Research Projects:
NRCS Plant Materials Program
As stated on the USDA Natural Resources Conservation Service (NRCS) Plant Materials Program website, the NRCS “operates 25 Plant Materials Centers (PMCs), each based in ecologically distinct areas, to evaluate plants and vegetative technologies to support USDA conservation programs and practices. PMCs find vegetative solutions to reduce soil erosion, increase cropland soil health and productivity, improve water quality, produce forage and biomass, improve air quality, improve wildlife habitat (including pollinator habitat), restore wetlands, protect streambank and riparian areas, and stabilize coastal areas.”
The PMCs in the Western States are:
Visit the NRCS website to review the research projects supported by each of these PMCs. These projects focus on the use of native plant species in habitat restoration. Here is a short list of a few of the Bridger PMC projects:
And here are a few projects from the Corvallis PMC:
The Alaska Plant Materials Center, in Palmer, Alaska, is sponsored by the Alaska Dept. of Natural Resources, Division of Agriculture, rather than by the NRCS. In addition to native plant species, this center also conducts research on traditional crops, such as varieties of potatoes that have been grown in Alaska for centuries and are well suited to the extreme climates of Alaska.
Great Basin Native Plant Project
The Great Basin covers a large expanse of the Western US, including most of Nevada, and portions of Utah, Colorado, Idaho, Oregon, and California, and stretches into Mexico. It is defined by its unique hydrology. All watersheds within the Great Basin drain into many small basins, rather than flowing externally to the Pacific Ocean or the Gulf of Mexico. The basin and range topography spreads from the lowest point in the Death Valley to the summit of Mount Whitney. The region is bounded by the Wasatch Mountains on the east, the Sierra Nevada and Cascade Ranges on the west, and the Snake River Basin to the north. Among many other lakes, it includes the Great Salt Lake and Lake Tahoe.
The Great Basin overlaps four separate deserts: the Mojave, the Colorado (part of the Sonoran Desert), the Great Basin and the Oregon High Deserts. It includes mountain forests and desert ecosystems. The region includes numerous rare, endangered, and endemic species, and each desert and mountain range holds its own definitive plant and animal species.
The website for the Great Basin Native Plant Project lists their mission as: “Providing knowledge, technology, and availability of native plant materials across the Great Basin.” This multi-state “research project was initiated in 2001 by the US Dept of the Interior Bureau of Land Management and the US Forest Service Rocky Mountain Research Station’s Grassland, Shrubland, and Desert Ecosystem Research Program.” The focus is on restoration of disturbed rangelands in the Western States, using native plant species.
Federal and State agencies, including numerous university researchers, are collaborating “to improve the availability of native plant materials” for use in restoration projects. The project collaborates with private seed companies, to improve availability of native seed. Several of the research projects are examining the impact of climate change on the Great Basin and the species within it. Refer to the Annual Progress Reports, posted on the GBNPP website, for details of their research.
Revegetation using native plants within highway rights-of-way
A helpful guide on the value of revegetating highway rights-of-way with native plants is Roadside use of native plants (2000), edited by Bonnie Harper-Lore and Maggie Wilson. This book includes a section for each State, identifying native species that might be considered as part of the revegetation of rights-of-way for that State and for use in landscaping within that State.
Niering, 2000, p. 28, points out that, “The highway rights-of-way across America represent a vast potential ecological resource in terms of supporting a diversity of natural and semi-natural plant communities. These rights-of-way can contribute significantly in promoting and preserving biodiversity which is now a current environmental issue of international concern.”
Texas DOT procedures for promotion of native plants along Texas roadsides
Because the Texas Department of Transportation procedures for maintaining roadways may be helpful to other States, I include below extensive excerpts from Texas Department of Transportation’s Roadside Vegetation Management Manual (revised May 2018). The Manual highlights the importance the State places on the promotion of native vegetation in Texas, and provides information on the importance of native plants. The full Manual is available on the Texas DOT website at http://onlinemanuals.txdot.gov/manuals/AlphaList.html#l_R
Guidelines for mowing along urban highways (p. 1-5):
“Establish non-mow or natural areas… to provide for wildflower preservation, regeneration of native plant species, and to create habitat for the Presidential Memorandum to Promote the Health of Honey Bees and Other Pollinators, and establishment of nesting habitat for wildlife.”
“Set cutting height as five inches… for strong regeneration of grasses.”
“Utilize an aggressive herbicide program with good vegetation management practices.” [The Manual includes guidelines on the use of herbicides].
The Manual includes guidelines for the protection of endangered and threatened plants and animals.
Guidelines for mowing along rural highways (p. 1-7):
“Establish non-mow or natural areas at appropriate locations within the right of way. These areas offer the best opportunity for wildflower propagation, native grass regeneration, and establishment of nesting cover for wildlife.”
“After maximizing the use of non-mow areas, use a maximum of two modified full-width cycles per year… Lands adjacent to Conservation Reserve Program (CRP) and forested properties, should be considered for non-mow areas… The first modified full-width cycle should be scheduled to allow wildflower seeds to mature and reset in late spring. The second modified full-width cycle, if necessary, should be scheduled for the late fall to provide maximum regeneration of native grasses, maintain nesting cover for wildlife and reduce vegetative competition with spring-blooming wildflowers [Note: they may have meant ‘fall-blooming wildflowers’ here]. Strip mowing may be used in lieu of modified full-width mowing cycles.
(P. 1-8) “Set cutting height no lower than seven inches to preserve wildflowers, create residual nesting cover, and to provide for strong regeneration of native grasses and nectar plants.
“Reseed all suitable areas with wildflowers as appropriate. The establishment of non-mow or natural areas provide excellent opportunities for the establishment of significant fall or perennial wildflower displays including fall blooming nectar plants for pollinators.”
(P. 1-10) “To avoid weakening a stand of native grasses, it is important that they not be cut too short or too often. Frequent mowing of native grasses would allow noxious weeds to invade. Once established, native warm season grasses…should be cut no lower than seven inches to ensure survivability.”
(P. 2-2) “Modified full-width mowing: To promote cost savings, on rural roadways with very wide rights-of-way or medians, mowing should be limited to a maximum of 30 foot width.” [The Manual lists exceptions and procedures for strip mowing and spot mowing].
(P 2-14) “Overspray herbicide applications must be coordinated with mowing operations to:
(P 2-16) “The main purpose of vegetation cover on the right of way is to protect the roadside from erosion… observing the [mowing] precautions contained in this section will help:
(P 3-2) “The Texas Department of Transportation has received nationwide recognition for its roadside wildflower program. Since 1929, the department has maintained the practice of withholding mowing until wildflowers have set mature seed and expanding the range of wildflower species…
“Planting roadsides with mixtures of native and introduced grasses, legumes, and wildflowers adheres to the department’s policy of:
(P 3-3) “Native and Introduced Grasses:
“Introduction: Native grasses have had thousands of years to adapt to various Texas climates and soils and they offer a definite advantage in highway right of way environments. Texas is a diverse state with varying climates and vegetative regions, so there is a definite need for selected introduced species of grasses to be included in our seed mixes to ensure quick vegetation coverage and to prevent erosion on the rights of way. Native grasses will prevail eventually, covering and stabilizing the right of way. Benefits of native grasses include:
“Establishment and growth: Native grasses are usually slow to establish and plantings may appear to have failed after the first growing season. Although the inspector may see weed-infested areas with only spindly and scattered individual grass plants, the stand is probably well on its way to becoming established. There are several reasons for the slow establishment:
(P 3-4) “Wildlife Habitat: Many of the game birds, songbirds, deer, rabbits and other small mammals that play an important role in the natural heritage of Texas depend on established stands of native grasses for nesting cover, den cover and food. Properly maintained highway rights of way covered with native grasses provide highly productive wildlife habitats. Research indicates that unmowed roadsides with native plant cover support two to three times the number of bird nests as those that are mowed annually.
“Many species of birds and mammals depend on roadsides during in at least a part of their life cycle. [Various species] will benefit from rights of way planting with native grasses intermixed with wildflowers.”
Page 3-5 includes guidelines for use of native seed, including information on reusing topsoil from roadway construction sites. Pages 3-8 to 3-26 provide extensive guidelines for wildflower propagation, including information on the wildflower species suitable to each vegetative region of Texas.
Chapter 4 includes pruning guidelines, including information on managing for oak wilt, a fungal disease that has killed many Texas oaks in recent decades.
Chapter 5 on vegetation management and wildlife habitat describes how much natural habitat has already been lost in Texas.
(P 5-2) “More than one-half of the wetland habitats in the continental United States have disappeared. Land use changes have resulted in similar losses of coastal wetlands in Texas. Almost two-thirds of hardwood bottomlands… are now gone. In the lower Rio Grande Valley, more than 95% of native brush has vanished. Native longleaf pine forests have declined from an estimated 6,000,000 acres to less than 1,000,000 acres. Some 95% of the originally occurring native prairies have also disappeared.”
The chapter points out that roadsides have become an important supplement to wildlife habitat, as natural habitats have declined.
(P 5-4) “Plant diversity is essential to maintaining an abundant and varied wildlife population. Growth structure is another important factor affecting the quality of wildlife habitats. ‘Growth structure’ simply refers to the height and coverage of the vegetative canopy. Promoting a diverse vegetative growth structure will also encourage wildlife diversity.” This section provides guidance for “mowing wisely” in a variety of diverse habitats, including intensive agricultural areas, wetlands, and rangelands. And it describes the value of including trees and shrubs in roadsides, to increase diversity of habitats for wildlife.
In a section on nurturing seeds, the Manual points out that allowing roadside plants to go to seed enables native seed to spread to surrounding areas. “In many areas of Texas, roadsides represent the only possible source for natural regeneration… Wildflower seeds provide food for many wildlife species, including birds and small mammals. The plants also participate in an intricate food web, supporting many insects and other invertebrates that other wild animals depend upon.”
Links to additional Rangeland Restoration practices:
Links to additional Innovative Solutions:
Revegetation with Native Plants to restore disturbed sites
Summaries of the research and commentary by Dr. Delena Norris-Tull, Professor Emerita of Science Education, University of Montana Western, September 2020.
Over the past few decades, more and more States and Federal Agencies have come to recognize the importance of revegetating disturbed lands with native plant species. And more and more programs have been developed, to conduct research on, or to grow and produce native plants and native seed, for use in landscaping and revegetation. Here are a few of those programs.
Native Plant Research Projects:
NRCS Plant Materials Program
As stated on the USDA Natural Resources Conservation Service (NRCS) Plant Materials Program website, the NRCS “operates 25 Plant Materials Centers (PMCs), each based in ecologically distinct areas, to evaluate plants and vegetative technologies to support USDA conservation programs and practices. PMCs find vegetative solutions to reduce soil erosion, increase cropland soil health and productivity, improve water quality, produce forage and biomass, improve air quality, improve wildlife habitat (including pollinator habitat), restore wetlands, protect streambank and riparian areas, and stabilize coastal areas.”
The PMCs in the Western States are:
- Bridger Plant Materials Center, in operation since 1959, located in Bridger, Montana, and serving Montana & Wyoming
- Lockeford Plant Materials Center, in operation since 1939, located in Lockeford, California
- Ho'olehua Plant Materials Center, in operation since 1957, in Hawaii, serving Hawaii and the Pacific Basic Area Islands: Guam, American Samoa, Northern Mariana Islands, Federated States of Micronesia, Republic of the Marshall Islands, and the Republic of Palau
- Aberdeen Plant Materials Center, in operation since 1939, located in Aberdeen, Idaho, and serving areas of Idaho, Nevada, Oregon, Utah, and Wyoming
- Great Basin Plant Materials Center, in operation since 2006, located in Fallon, NV, and serving areas of Nevada, Oregon, California, and Utah
- Los Lunas Plant Materials Center, in operation since 1937, located in Los Lunas, NM, and serving areas of Arizona, Colorado, New Mexico, and Utah
- Corvallis Plant Materials Center, in operation since 1957, located in Corvallis, OR, and serving areas of California, Oregon, and Washington
- Pullman Plant Materials Center, in operation since 1935, located in Pullman, WA, and serving areas of Idaho, Oregon, and Washington
Visit the NRCS website to review the research projects supported by each of these PMCs. These projects focus on the use of native plant species in habitat restoration. Here is a short list of a few of the Bridger PMC projects:
- Bluebunch wheatgrass initial evaluation planting comparing the performance of 65 seed sources for use in eastern Montana and Wyoming.
- Comparative study testing the performance of Plant Materials selection against local seed sources for restoration of weed invaded areas.
- Montana Native Plants for Pollinator-Friendly Plantings highlights the importance of establishing nectar and pollen sources, shelter and breeding environments for pollinators and other beneficial insects.
And here are a few projects from the Corvallis PMC:
- Facilitate commercial availability of native plants and seed through development and publication of seed production and plant propagation protocols such as the Native Seed Production Manual for the Pacific Northwest.
- Collaborate with US Fish and Wildlife Service and other partners to grow seed of select populations of threatened and endangered plant species and nectar/host plants for threatened and endangered butterflies in order to meet goals laid out in recovery plans.
- Promote establishing, maintaining, and enhancing habitat for pollinators, beneficial insects, and other wildlife on working lands through field trials, training, and development of technical publications. Practices include hedgerows, windbreaks, riparian plantings, conservation cover, insectary plantings, buffer strips, and cover crops.
The Alaska Plant Materials Center, in Palmer, Alaska, is sponsored by the Alaska Dept. of Natural Resources, Division of Agriculture, rather than by the NRCS. In addition to native plant species, this center also conducts research on traditional crops, such as varieties of potatoes that have been grown in Alaska for centuries and are well suited to the extreme climates of Alaska.
Great Basin Native Plant Project
The Great Basin covers a large expanse of the Western US, including most of Nevada, and portions of Utah, Colorado, Idaho, Oregon, and California, and stretches into Mexico. It is defined by its unique hydrology. All watersheds within the Great Basin drain into many small basins, rather than flowing externally to the Pacific Ocean or the Gulf of Mexico. The basin and range topography spreads from the lowest point in the Death Valley to the summit of Mount Whitney. The region is bounded by the Wasatch Mountains on the east, the Sierra Nevada and Cascade Ranges on the west, and the Snake River Basin to the north. Among many other lakes, it includes the Great Salt Lake and Lake Tahoe.
The Great Basin overlaps four separate deserts: the Mojave, the Colorado (part of the Sonoran Desert), the Great Basin and the Oregon High Deserts. It includes mountain forests and desert ecosystems. The region includes numerous rare, endangered, and endemic species, and each desert and mountain range holds its own definitive plant and animal species.
The website for the Great Basin Native Plant Project lists their mission as: “Providing knowledge, technology, and availability of native plant materials across the Great Basin.” This multi-state “research project was initiated in 2001 by the US Dept of the Interior Bureau of Land Management and the US Forest Service Rocky Mountain Research Station’s Grassland, Shrubland, and Desert Ecosystem Research Program.” The focus is on restoration of disturbed rangelands in the Western States, using native plant species.
Federal and State agencies, including numerous university researchers, are collaborating “to improve the availability of native plant materials” for use in restoration projects. The project collaborates with private seed companies, to improve availability of native seed. Several of the research projects are examining the impact of climate change on the Great Basin and the species within it. Refer to the Annual Progress Reports, posted on the GBNPP website, for details of their research.
Revegetation using native plants within highway rights-of-way
A helpful guide on the value of revegetating highway rights-of-way with native plants is Roadside use of native plants (2000), edited by Bonnie Harper-Lore and Maggie Wilson. This book includes a section for each State, identifying native species that might be considered as part of the revegetation of rights-of-way for that State and for use in landscaping within that State.
Niering, 2000, p. 28, points out that, “The highway rights-of-way across America represent a vast potential ecological resource in terms of supporting a diversity of natural and semi-natural plant communities. These rights-of-way can contribute significantly in promoting and preserving biodiversity which is now a current environmental issue of international concern.”
Texas DOT procedures for promotion of native plants along Texas roadsides
Because the Texas Department of Transportation procedures for maintaining roadways may be helpful to other States, I include below extensive excerpts from Texas Department of Transportation’s Roadside Vegetation Management Manual (revised May 2018). The Manual highlights the importance the State places on the promotion of native vegetation in Texas, and provides information on the importance of native plants. The full Manual is available on the Texas DOT website at http://onlinemanuals.txdot.gov/manuals/AlphaList.html#l_R
Guidelines for mowing along urban highways (p. 1-5):
“Establish non-mow or natural areas… to provide for wildflower preservation, regeneration of native plant species, and to create habitat for the Presidential Memorandum to Promote the Health of Honey Bees and Other Pollinators, and establishment of nesting habitat for wildlife.”
“Set cutting height as five inches… for strong regeneration of grasses.”
“Utilize an aggressive herbicide program with good vegetation management practices.” [The Manual includes guidelines on the use of herbicides].
The Manual includes guidelines for the protection of endangered and threatened plants and animals.
Guidelines for mowing along rural highways (p. 1-7):
“Establish non-mow or natural areas at appropriate locations within the right of way. These areas offer the best opportunity for wildflower propagation, native grass regeneration, and establishment of nesting cover for wildlife.”
“After maximizing the use of non-mow areas, use a maximum of two modified full-width cycles per year… Lands adjacent to Conservation Reserve Program (CRP) and forested properties, should be considered for non-mow areas… The first modified full-width cycle should be scheduled to allow wildflower seeds to mature and reset in late spring. The second modified full-width cycle, if necessary, should be scheduled for the late fall to provide maximum regeneration of native grasses, maintain nesting cover for wildlife and reduce vegetative competition with spring-blooming wildflowers [Note: they may have meant ‘fall-blooming wildflowers’ here]. Strip mowing may be used in lieu of modified full-width mowing cycles.
(P. 1-8) “Set cutting height no lower than seven inches to preserve wildflowers, create residual nesting cover, and to provide for strong regeneration of native grasses and nectar plants.
“Reseed all suitable areas with wildflowers as appropriate. The establishment of non-mow or natural areas provide excellent opportunities for the establishment of significant fall or perennial wildflower displays including fall blooming nectar plants for pollinators.”
(P. 1-10) “To avoid weakening a stand of native grasses, it is important that they not be cut too short or too often. Frequent mowing of native grasses would allow noxious weeds to invade. Once established, native warm season grasses…should be cut no lower than seven inches to ensure survivability.”
(P. 2-2) “Modified full-width mowing: To promote cost savings, on rural roadways with very wide rights-of-way or medians, mowing should be limited to a maximum of 30 foot width.” [The Manual lists exceptions and procedures for strip mowing and spot mowing].
(P 2-14) “Overspray herbicide applications must be coordinated with mowing operations to:
- Ensure effective control of target plant species
- Avoid damage to desirable plant species such as wildflowers, legumes, and forbs beneficial to wildlife.
(P 2-16) “The main purpose of vegetation cover on the right of way is to protect the roadside from erosion… observing the [mowing] precautions contained in this section will help:
- Ensure efficient and environmentally sound mowing operations
- Promote wildlife habitat
- Maintain seed sources for the state’s native flora.”
(P 3-2) “The Texas Department of Transportation has received nationwide recognition for its roadside wildflower program. Since 1929, the department has maintained the practice of withholding mowing until wildflowers have set mature seed and expanding the range of wildflower species…
“Planting roadsides with mixtures of native and introduced grasses, legumes, and wildflowers adheres to the department’s policy of:
- Providing a safe and comfortable road network…
- Enhancing environmental protection and developing over 800,000 acres of roadside wildlife habitat
- Reducing erosion losses…
- Providing cost-efficient maintenance activities”
(P 3-3) “Native and Introduced Grasses:
“Introduction: Native grasses have had thousands of years to adapt to various Texas climates and soils and they offer a definite advantage in highway right of way environments. Texas is a diverse state with varying climates and vegetative regions, so there is a definite need for selected introduced species of grasses to be included in our seed mixes to ensure quick vegetation coverage and to prevent erosion on the rights of way. Native grasses will prevail eventually, covering and stabilizing the right of way. Benefits of native grasses include:
- excellent erosion control once established and maintained properly
- long lived (up to 100 years)
- excellent wildlife habitat (food and cover)
- highly resistant to invasions of noxious weeds
- low maintenance costs
- well adapted to Texas soils and climates
- resistant to agricultural chemical runoffs
- aesthetically pleasing
- part of our natural heritage.
“Establishment and growth: Native grasses are usually slow to establish and plantings may appear to have failed after the first growing season. Although the inspector may see weed-infested areas with only spindly and scattered individual grass plants, the stand is probably well on its way to becoming established. There are several reasons for the slow establishment:
- Native grasses commonly have more extensive root development than above-ground growth during the first year.
- Many native grasses do not begin growing until late spring or early summer, making their first year growing season short.
- A stand of native grasses generally requires about three years to reach maturity. Once native grasses become established, however, very few weeds can compete with them for essential nutrients and water in the soil. At maturity, native grasses may have a fibrous root system extending to a depth of 5 feet or more.”
(P 3-4) “Wildlife Habitat: Many of the game birds, songbirds, deer, rabbits and other small mammals that play an important role in the natural heritage of Texas depend on established stands of native grasses for nesting cover, den cover and food. Properly maintained highway rights of way covered with native grasses provide highly productive wildlife habitats. Research indicates that unmowed roadsides with native plant cover support two to three times the number of bird nests as those that are mowed annually.
“Many species of birds and mammals depend on roadsides during in at least a part of their life cycle. [Various species] will benefit from rights of way planting with native grasses intermixed with wildflowers.”
Page 3-5 includes guidelines for use of native seed, including information on reusing topsoil from roadway construction sites. Pages 3-8 to 3-26 provide extensive guidelines for wildflower propagation, including information on the wildflower species suitable to each vegetative region of Texas.
Chapter 4 includes pruning guidelines, including information on managing for oak wilt, a fungal disease that has killed many Texas oaks in recent decades.
Chapter 5 on vegetation management and wildlife habitat describes how much natural habitat has already been lost in Texas.
(P 5-2) “More than one-half of the wetland habitats in the continental United States have disappeared. Land use changes have resulted in similar losses of coastal wetlands in Texas. Almost two-thirds of hardwood bottomlands… are now gone. In the lower Rio Grande Valley, more than 95% of native brush has vanished. Native longleaf pine forests have declined from an estimated 6,000,000 acres to less than 1,000,000 acres. Some 95% of the originally occurring native prairies have also disappeared.”
The chapter points out that roadsides have become an important supplement to wildlife habitat, as natural habitats have declined.
(P 5-4) “Plant diversity is essential to maintaining an abundant and varied wildlife population. Growth structure is another important factor affecting the quality of wildlife habitats. ‘Growth structure’ simply refers to the height and coverage of the vegetative canopy. Promoting a diverse vegetative growth structure will also encourage wildlife diversity.” This section provides guidance for “mowing wisely” in a variety of diverse habitats, including intensive agricultural areas, wetlands, and rangelands. And it describes the value of including trees and shrubs in roadsides, to increase diversity of habitats for wildlife.
In a section on nurturing seeds, the Manual points out that allowing roadside plants to go to seed enables native seed to spread to surrounding areas. “In many areas of Texas, roadsides represent the only possible source for natural regeneration… Wildflower seeds provide food for many wildlife species, including birds and small mammals. The plants also participate in an intricate food web, supporting many insects and other invertebrates that other wild animals depend upon.”
Links to additional Rangeland Restoration practices:
Links to additional Innovative Solutions: