Advances in Restoration Technology
Thought Leadership Article By: Jason Stettler, PhD
Introduction:
Ecological restoration has been a cornerstone of federal and state land management agencies in the Western United States for nearly a century, yet direct seeding projects can have over a 95% failure rate for seedling establishment. On average, federal agencies have seeded over 210,000 acres per year since 1950 (1). The success rate for these projects, however, has historically been very low with seeded species failing to establish (2) with typically fewer than 5 seeds that germinate, emerge, and establish to maturity for every 100 seeds that are sown. This is an incredibly low number when you consider that a seed mix will have between 40 and 100 seeds per square foot (SF) over every acre of a project (drill seeding uses 40-60 seeds per SF and broadcast seeding uses 75-100 seeds per SF). Although multiple factors encourage this incredibly low number, the biggest contributors include: invasive weed species, especially annual grasses, low precipitation during the planting year, prolonged drought cycles, project timing (spring vs. fall), and utilizing plant materials that are poorly adapted to the project or site.
Roadblocks and Hurdles:
The early days of restoration work involved using mostly exotic species like Crested wheatgrass (Agropyron cristatus) to fight the invasion of highly toxic Halogeton (Halogeton glomeratus) that was taking over rangelands and causing considerable loss of livestock (3). Although Crested wheatgrass was effective in combatting invasive species, it provided little value to wildlife, pollinators, and ecosystem biodiversity and function. Restoration objectives and practices have evolved during the past 75 years and land management agencies now strive to restore healthy ecosystems with a diverse mix of native grasses, forbs, and shrubs to enhance ecosystem function and biodiversity, improve grazing quality, suppress invasive species, and reduce wildfires.
The biggest hurdle in the past was species availability. Crested wheatgrass was an available forge grass species used in dryland grazing for centuries in Europe/Asia and was introduced to the United States in the early 1900’s. It had a proven track record and available seed sources/producers, so it was an obvious pick to fight invasive species and reclaim the landscape. The seeds of many native grasses, shrubs, and forb species are currently abundant in the thriving native seed industry and market place, so availability is no longer a limiting factor in successful ecological restoration.
One of the biggest hurdles to successful restoration today is unpredictable weather patterns including prolonged droughts and unseasonal heatwaves. We can’t control or predict these weather events to ensure success, so the question becomes, how can we improve the success rates of our restoration projects? We suggest that by improving our methods, we plan for greater successful outcomes. Although there are several ways to increase efficiency, we will focus our discussion on seed coating technologies and live plant based restoration.
Seed Coating:
The current research shows that seed coating technology is one of the best scalable ways to improve restoration success rates in annual grass-invaded landscapes. The control of annual grasses is fairly inexpensive and effective with pre-emergent herbicides. However, these chemical treatments are not selective and will kill the good seeds with the bad. In other words, you can’t control the weeds AND plant seeds in the same season, but if you don’t control the weeds your emerging seedlings will be outcompeted for resources by the aggressive weeds. This is where seed coating technology comes into play. Activated carbon effectively neutralizes herbicides and pre-emergents, so when coated on the restoration seeds, the weeds can be controlled without harming the seeded species (4).
The advancements in seed coating technologies don’t stop there. Activated carbon can be combined with other polymers, chemicals, and hormones to improve multiple challenges that the seed faces once planted. These include tackifiers to absorb and hold water to improve imbibition (5), fungicides to prevent diseases like dampening off (6), surfactants to improve hydrophobic soils formed after wildfires (7), and hormones that improve germination at the right time of the year (8-9). For example, a seed that is primed for germination will often germinate in the fall and be killed by frost and freezing conditions. However, a primed seed that is coated with abscisic acid will delay germination until the hormone is leached into the soil throughout the winter, which causes it to germinate at the right time in the spring and increases the overall survival rate. Other coatings such as insecticide and capsaicin (chili pepper extract) can be applied to reduce seed predation by ants and rodents (10). Although some seed coating technology, such as fungicides and inoculants, has been used in agricultural seed for many decades, the application to wildland/reclamation seed is still novel and has just begun to be adopted at restoration scales.
Live Plants:
Another way to avoid the pitfalls involved with poor germination rates and high seedling mortality rates is to avoid direct seeding entirely and install live plants. Live plant based restoration utilizes keystone species like Big Sagebrush (Artemisa tridetata), Antelope bitterbrush (Purshia tridentata), and Fourwing saltbush (Atriplex canescens) to jumpstart the natural succession process by several years (11-13). These keystone species typically grow slowly from seed in nature due to the harsh conditions of western rangelands, and will typically take several years for a naturally recruited seedling to be 4-6 inches in height. However, when these are grown in the controlled environments of greenhouse systems, seed germination is greatly improved and seedlings can reach up to 6-inches tall in a single growing season. These plants of advanced size and maturity establish very quickly with high survival rates. Fourwing saltbush seedling transplants, for example, have up to 67% survival compared to only 9% of emerged seedlings from direct seeding after 5 years (13).
EcoPoint has found that the timing of live plant installation in western rangelands is almost as crucial to success as using the right germplasm sources. Winter precipitation in the Sagebrush Steppe typically comprises over 50% of annual precipitation, so we exploit this vital resource by installing live plants in the fall. EcoPoint has found that an October installation is an optimal time for much of the northern Sagebrush Steppe. During this period the soil moisture profile is usually within the top few inches of the surface. The soil also remains warmer than the air temperatures longer into the season, so the roots are able to actively grow and will mine deep into the soil before going dormant at the onset of winter. EcoPoint also prepares our seedlings for installation by gradually exposing them to the harsher conditions of nature to reduce transplant shock and improve establishment rates.
We’ve observed survival rates that are very high for plants installed the first day of the project and decrease each day it takes the contractor to install the plants. The reason is because the soil and plants desiccate in their pots while waiting at the site to be transplanted. This detail often gets overlooked by land managers and contractors, but can be easily resolved by regularly watering the plants after they are moved to the restoration site. EcoPoint actively monitors and records plant survival seasonally to provide real time data delivery to our customers. Using live plants for restoration is highly effective and will lead to higher success rates and long term establishment of a thriving ecosystem.
Conclusion:
Restoration methods and practices are as varied as the western rangelands are vast, and there is no single method that works for all project conditions and objectives. However, by implementing these technologies and practices ecological restoration success rates will increase. The cost of implementing these new practices are much lower than the cost of project failure, which leads to more invasive annual species and increased fire risks. Restoring our damaged ecosystems and returning them to biodiversity hotspots is possible and the advancements we discussed are getting us closer every year.
Works Cited:
1. Pilliod, D. S., Welty, J. L., & Toevs, G. R. (2017). Seventy-five years of vegetation treatments on public rangelands in the Great Basin of North America. Rangelands, 39(1), 1-9.
2. Copeland, S. M., Baughman, O. W., Boyd, C. S., Davies, K. W., Kerby, J., Kildisheva, O. A., & Svejcar, T. (2021). Improving restoration success through a precision restoration framework. Restoration Ecology, 29(2), e13348.
3. Tisdale, E. W., & Zappetini, G. (1953). Halogeton studies on Idaho ranges. Rangeland Ecology & Management/Journal of Range Management Archives, 6(4), 225-236.
4. Davies, K. W., Clenet, D. R., Madsen, M. D., Brown, V. S., Ritchie, A. L., & Svejcar, L. N. (2024). Activated carbon seed technologies: Innovative solutions to assist in the restoration and revegetation of invaded drylands. Journal of Environmental Management, 371, 123281.
5. Madsen, M. D., Davies, K. W., Boyd, C. S., Kerby, J. D., & Svejcar, T. J. (2016). Emerging seed enhancement technologies for overcoming barriers to restoration. Restoration Ecology, 24, S77-S84.
6. Hoose, B. W., Geary, B. D., Richardson, W. C., Petersen, S. L., & Madsen, M. D. (2022). Improving dryland seedling recruitment using fungicide seed coatings. Ecological Solutions and Evidence, 3(1), e12132.
7. Madsen, M. D., Zvirzdin, D. L., Roundy, B. A., & Kostka, S. J. (2014). Improving reseeding success after catastrophic wildfire with surfactant seed coating technology. American Society for Testing and Materials STP, 1569, 44-55.
8. Larson, A. J., Cartwright, M. M., Jones, W. D., Luce, K., Chen, M. Y., Petersen, K., … & Madsen, M. D. (2023). Slow release of GA3 hormone from polymer coating overcomes seed dormancy and improves germination. Plants, 12(24), 4139.
9. Richardson, W. C., Badrakh, T., Roundy, B. A., Aanderud, Z. T., Petersen, S. L., Allen, P. S., … & Madsen, M. D. (2019). Influence of an abscisic acid (ABA) seed coating on seed germination rate and timing of bluebunch wheatgrass. Ecology and Evolution, 9(13), 7438-7447.
10. Pearson, D. E., Valliant, M., Carlson, C., Thelen, G. C., Ortega, Y. K., Orrock, J. L., & Madsen, M. D. (2019). Spicing up restoration: can chili peppers improve restoration seeding by reducing seed predation?. Restoration Ecology, 27(2), 254-260.
11. Davies, K. W., Bates, J. D., & Clenet, D. (2020). Improving restoration success through microsite selection: an example with planting sagebrush seedlings after wildfire. Restoration Ecology, 28(4), 859-868.
12. Davies, K. W., Boyd, C. S., Bates, J. D., & Gearhart, A. (2017). Legacy microsite effect on the survival of bitterbrush outplantings after prescribed fire: capitalizing on spatial variability to improve restoration. Restoration Ecology, 25(5), 723-730.
13. Jonas, J. L., Grant-Hoffman, M. N., & Paschke, M. W. (2018). Restoration of North American salt deserts: A look at the past and suggestions for the future. Ecological Restoration, 36(3), 177-194.