RestoreNet: Collaboration to Improve Success of Seed-Based Restoration

Introduction

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Land degradation in arid and semiarid ecosystems is often difficult to reverse because low rainfall and high temperatures impede reestablishment of vegetation. Seed-based restoration success and recovery rates are also impeded by harsh climatic conditions and remain extremely low. Additionally, little information is available to land managers about the performance of contrasting seed-based restoration techniques and seed mixes to help increase restoration success. Researchers from the U.S. Geological Survey (USGS), Colorado State University, University of Arizona, New Mexico State University, Northern Arizona University, and University of California-Riverside are working with land managers from local ranches, federal, state, and tribal land management agencies to implement a network of restoration field trials collectively called “RestoreNet”. RestoreNet tests the effectiveness of different combinations of restoration treatments and seeded plant species in a small scale, low risk environment. Researchers co-produce this knowledge with land managers to inform practices that are likely to be successful following large-scale disturbance across the southwestern U.S. and Colorado Plateau. 

In water-limited ecosystems, treatments that increase soil water retention can increase germination and establishment of plants. How the preferred climate conditions of the seeded plant species (warm/dry or cool/wet season species) align with post-seeding weather at the restoration site can also influence success. From 2018 to present, USGS and university researchers collaborated with land managers to establish treatment plots across the southwestern US and implemented treatments in the season rainfall typically occurs. In the Colorado Plateau, this is typically between July and September. Each plot received one of five treatments: control, seeded only, or seeded plus wood mulch, pitting, or above-ground structure structure
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Learn more about structure called a Connectivity Modifier (ConMod). Wood mulch was taken from regional forest thinning projects; pitting is a traditional practice still used by southwestern U.S. tribes where small pits are dug into the soil to catch water after rain; and the above-ground structures mimic nurse plants by increasing shade, reducing wind speed, and intercepting runoff water. The perennial grasses and forbs used in seeding trials are native to the region the trial is implemented, and were selected based on prevalence of use in the region, land manager priorities, and commercial availability. Although it remains largely untested, using heat- and drought-tolerant species may become more suitable as the degree of aridity from climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

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Land managers often test multiple revegetation methods on small scales but the lessons learned are not often shared with other land managers who have similar climate and soil conditions. To encourage greater knowledge sharing, researchers from the USGS and universities are partnering with land managers to share lessons learned from RestoreNet broadly across the Southwest. Each RestoreNet site is co-produced with land managers and landowners that are seeking optimal restoration techniques for the area in which they work. Results from RestoreNet are being shared through regular field trips, workshops, reports, the RestoreNet website, and publications in scientific research journals. 

Key Issues Addressed

Drylands are highly vulnerable to climate change as ecosystems here exist in a precarious balance with available water resources, like soil moisture. Because soil moisture is the primary factor limiting seedling recruitment, treatments that increase water retention can support germination in these water-limited ecosystems to improve establishment. There is a need to test restoration treatments that can effectively increase soil moisture and improve success of dryland restoration.

The plant species used for restoration projects have unique climate preferences (wet/cool and hot/dry). It remains unknown which species (and climate preferences) to prioritize for improvement of short- and-long term restoration success.

Land managers may have little information available to them about best management practices for restoration that are likely to be effective under climate change and implementable at large scales. When restoration methods are tested, the results are often not shared in a way that is accessible to land managers working under similar conditions.

Project Goals

• Test the ability of above-ground structures, surface wood mulch, and below-ground pitting to prolong soil moisture and help seeds grow. 
• Improve guidance for seed mixes by testing native species that grow in wetter and cooler conditions with those growing in hotter and drier conditions which are potentially more climate change adapted.
• Co-develop field trials with land managers to find cost-effective solutions for stakeholders that face restoration challenges while increasing the availability of this information for land managers across the Southwest.

Project Highlights

More to Come: This was the first year of an ongoing study that covers all drylands in the Southwest. Additional results will be posted to www.usgs.gov/sbsc/ramps as they become available!

• Traditional Ecological Knowledge: Pitting is a traditional gardening practice of Zuni Pueblo and other southwestern Native American Tribes that has been used for millennia and is still in use today. 
• The Winning Treatment: The pitting treatments were the most successful on the Colorado Plateau, resulting in 44.2% higher seedling density while also limiting the establishment of non-native species threefold relative to the unseeded control. 
• Which Treatment to Use & Which Species to Plant?: Combining seeding with any of the three restoration treatments (mulching, pitting or above-ground structures), increased seedling density, regardless of the plant species used. However, the seed mix containing species who tend to grow in cooler and wetter conditions had higher germination success than the warm-dry mix in the wetter than normal year of the study.
• Land Manager Participation: Active participation of land managers was critical to project success. Participation was incentivized by allowing space to try restoration treatments tailored to problems each land manager is facing on the land they managed. The techniques used were informed by how likely they are to be used by partners.
• Report Cards: RestoreNet researchers produced regular “report cards” to communicate the results of the trials to project partners. Sharing report cards meant partners met regularly, stayed informed and involved in the project, and ensured that objectives were being met. 

Lessons Learned

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The success of pitting, compared to mulch and above-ground structures, may be due to how pits increase soil moisture. Pits capture water when it rains by pooling and slowing water down, whereas mulch reduces evaporation from the soil surface. In addition to digging pits, it may be possible to make use of areas that already have a lot of natural pits and roughness that slow and capture water to increase success of seeding efforts.

Despite the positive effects of the above-ground structures on seedling recruitment found in past studies, they were the least effective of the three restoration treatments used in this study. Above-ground structures mostly increased non-seeded invasive annual species rather than seeded perennial species. This was also the case for other restoration treatments. Overall, The establishment of unseeded species was ~three times higher than that of seeded species and ~40% of these species were non-native annuals. 

The relatively wet/cool conditions in the initial study period may explain why the wet/cool species had higher success rates than the hot/dry species. However, it may be better to use both wet/cool and warm/dry species in seed mixes to help hedge bets against a range of climate conditions that the site may experience, especially more arid conditions that are forecasted with climate change. 

RestoreNet successfully identified interested land managers with specific restoration goals by reaching out through networks of the U.S. Geological Survey Restoration Assessment and Monitoring Program of the Southwest, which orchestrates RestoreNet. Actively engaging land managers, landowners, and restoration practitioners helps with the development of restoration methods and selection of seeded plant species, in addition to helping with interpretation of the results of the field trials.

Next Steps

• Re-install the experiment on the same sites to compare results across different weather years. 
• Experiment with new treatments including soil amendments, seed coating technologies, timing of seeding, seed provenance (where seed is sourced), and more.
• Provide insight about modifications to the list of priority restoration species to account for anticipated changes in climate. 

Resources

• Sign up for RestoreNet newsletters at: https://listserv.usgs.gov/mailman/listinfo/ramps
• Restoration Assessment and Monitoring Program of the Southwest
• Zuni Waffle Gardening
• RestoreNet website
• Aqua Fria National Monument
• Montezuma Well National Monument
• Petrified Forest National Park

Contacts

Molly McCormick, USGS/RAMPS: mmccormick@usgs.gov

CART Lead Author

Ariel Léger, Grassland Coordinator, CCAST: arielleger@arizona.edu

Suggested Citation

Munson, S.M., M.L. McCormick, and Scott, M. (2022). “RestoreNet: Collaboration to Improve Success of Seed-Based Restoration on the Colorado Plateau.” CCAST. Retrieved from https://www.fws.gov/project/restorenet-collaboration-improve-success-seed-based-restoration.