Opening letter

Hello and happy end of summer! My name is Laura Shriver, and I started as the RAMPS coordinator in February 2023. I have a background working with native plant materials development and restoration in the Southwest and Great Basin, and I am looking forward to working with RAMPS stakeholders and collaborators to research and share the best ways to manage and restore dryland ecosystems. In this issue of our newsletter, we share recent research from RAMPS and the U.S. Geological Survey (USGS), Southwest Biological Research Center (SBSC), look back on the 2023 field season, and outline future RestoreNet plans. I’m looking forward to working with you and please feel free to connect with me at lshriver@usgs.gov or 928 556 7305.

Warmly,

Laura Shriver

RAMPS Coordinator

IN THE FIELD

Monitoring during a “superbloom”

The Southwest had an abnormally wet 2022 – 2023 winter, producing what many have called a “superbloom” when large amounts of plants emerge and flower, often occurring in drylands in response to above average precipitation and soil moisture. This strategy, emerging and flowering only when conditions are just right, is adaptive for many species to make the most of their limited resources.

Many of our RestoreNet sites had higher than average winter precipitation, and we saw a lot of plant emergence and growth at these sites. At many sites, plants emerged that we had never seen before. This abundance of life in RestoreNet plots is ecologically exciting, and we are looking forward to exploring how increased precipitation interacts with the RestoreNet treatments.

Sources/Usage: Public Domain. View Media Details

Sources/Usage: Public Domain. View Media Details

RestoreNet Version 2.0 and Livestock Grazing

In 2023, RAMPS and collaborators received a Western Sustainable Agriculture Research and Education (WSARE) grant to incorporate live soil inoculation, seed balls, and livestock grazing into RestoreNet seeding treatments. Researchers, including Caroline Harvilla from Colorado State University, Kitty Gehring from Northern Arizona University, Elise Gornish from the University of Arizona, and Seth Munson at USGS will investigate the effects of these treatments on seeding success and soil health in partnership with land manager and owner collaborators. This project builds on RestoreNet Version 1.0 to see if restoration outcomes can be improved by increasing beneficial soil microbial communities in degraded soils. Soil will be gathered at reference sites near existing RestoreNet sites in less disturbed, intact plant communities, then beneficial microbes will be increased in the greenhouse before applying soil at RestoreNet sites along-side direct seeding and seedball treatments.

The WSARE grant allows RAMPS to fine-tune our inoculation and seedball methods and test the effects of livestock in tandem with seeding at a subset of RestoreNet sites. Specifically, we will see if flash grazing immediately after seeding could increase seedling emergence through increasing soil-seed contact, creating micro-topography, adding nutrients, and reducing weed cover.

So far, RestoreNet 2.0 has been installed at 13 sites, and in 2024 we will install the treatments at 10 sites. Dr. Kitty Gehring of Northern Arizona University and her lab will help adjust soil inoculation methods and collect soil samples alongside monitoring data in the 2023 growing season. We are looking forward to working with RestoreNet land managers and landowners on this project to produce actionable science that can inform seed-based restoration throughout the Southwest.

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RESEARCH UPDATES

New Publications

What influences seeding success in RestoreNet restoration experiments?

New RAMPS RestoreNet paper finds that soil surface treatments and precipitation timing determine seedling development

The RAMPS RestoreNet project is a growing network of 21 diverse dryland restoration sites across the southwestern United States. These restoration sites received a standardized set of seed mixes and soil surface treatments (pits, mulch, and ConMod artificial nurse plants) designed to enhance seedling establishment. In this paper, RestoreNet collaborators explored the effects of seed mix, soil surface treatments, site characteristics, and temporal environmental variables on seedling emergence, survival, and growth over 3 years of RestoreNet experiments. Generally, they found that soil surface treatments and timing of precipitation were more important than determining seeding success than site-specific characteristics. Using soil surface treatments in tandem with seeding promoted up to 3x greater seedling emergence densities compared with seeding alone, and the positive effect of soil surface treatments became more prominent with increased cumulative precipitation since seeding. The presence of exotic species exerted a negative influence on seedling survival and growth, but not initial emergence. These findings, among others, suggest that seeded species recruitment across drylands can generally be promoted, regardless of location, by (1) incorporation of soil surface treatments, (2) employment of near-term seasonal climate forecasts, (3) suppression of exotic species, and (4) seeding multiple times.

CITATION: Farrell, H.L., Munson, S.M., Butterfield, B.J., Duniway, M.C., Faist, A.M, Gornish, E. S., Harvilla, C., Larios, L., Reed, S.C., Rowe, H.I., Laushman, K.M., McCormick, M.L. (2023). Soil surface treatments and precipitation timing determine seedling development across southwestern US restoration sites. Ecological Applications, 33(4), e2834. DOI: https://doi.org/10.1002/eap.2834

How does drought tolerance influence RestoreNet outplant success?

New paper demonstrates how drought tolerance predicts restoration success across degraded drylands

Eight of our RestoreNet project sites on the Colorado Plateau received plants initially grown in the greenhouse (outplants) to promote revegetation. RAMPS ecologists examined the relationship between drought responses of the outplants in the greenhouse and their survival in the field. To assess drought response, the researchers compared outplant physiological responses to increasingly dry conditions for 12 common grass and forb species used in restoration on the Colorado Plateau.  Plant species that were able to reduce water in their stem tissues (stem water potential) and maintain water movement through their leaf pores (stomatal conductance) in response to drought did better in restoration sites. This effect was magnified in the driest restoration sites, suggesting that species with physiological adaptations to drought may be some of the best candidates for dryland restoration. The findings suggest that plant species have diverse strategies to resist drought, which is critical to restoration success. As precipitation patterns are forecasted to become more variable in the coming decades, the future success of restoration will become more dependent on capitalizing on periods of favorable moisture and intentionally selecting suitable plant species with effective plant water-use strategies.

CITATION: Butterfield, B.J., Munson, S.M., Farrell, H.L. (2023). Plant water-use strategies predict restoration success across degraded drylands. Journal of Applied Ecology, 60, 1170-1180. DOI: 10.1111/1365-2664.14393

Treating invasive buffelgrass in Saguaro National Park

New paper explores lessons from 10 years of buffelgrass treatments in Saguaro National Park

Buffelgrass (Pennisetum ciliare) is a highly invasive perennial grass in the Sonoran Desert that increases the risk of wildfire and harms native plant communities. Saguaro National Park has been controlling buffelgrass spread with chemical and mechanical treatments for over two decades. RAMPS teamed up with collaborators at the Arizona-Sonora Desert Museum, University of Arizona, and Saguaro National Park to assess the effectiveness of 10 years of treatment in the park, with a focus on how treatments were influenced by stage of invasion, treatment type and intensity, and environmental conditions. The researchers found that treatments can be effective in all but the smallest patches of buffelgrass and found that chemical treatments (glyphosate-based herbicides) were as effective or more effective than mechanical treatments. One of best ways to improve treatment success was to treat buffelgrass more frequently, ideally leaving no more than three years between treatments. Buffelgrass treatments can also be improved by frequent surveillance as small patches can be treated effectively and can spread quickly.

CITATION: Li, Y.M., Munson, S.M., Lin, Y.C., Grissom, P. (2023). Effectiveness of a decade of treatments to reduce invasive buffelgrass (Penisetum ciliare). Invasive Plant Science and Management, 16(1), 27-37. DOI: https://doi.org/10.1017/inpt.2023.2

How do nurse plant effects change over time?

New paper addresses this question and restoration implications in Joshua Tree National Park

Nurse plants are perennial plants that benefit the plants growing under their canopies by creating a favorable microclimate. However, we know little about how these benefits may change over time as the nurse plant ages, or if perennials reestablished through restoration can benefit their neighbors as much as natural nurse plants. RAMPS and collaborators at the University of Nevada, Las Vegas addressed these questions through a 12-year study assessing plant communities below native perennials outplanted at disturbed restoration sites compared to open spaces and natural perennials in undisturbed sites in Joshua Tree National Park in the Mojave Desert. The results did not support their hypothesis that facilitation would increase as nurse plants aged. Instead, facilitation by outplants was intermittent and depended on other factors including the group of beneficiary species (native of non-native) and measurement year. Researchers found that non-native plants were facilitated by outplants that were 1-9 years old, but facilitation switched to native plants as outplanted matured to 9-12 years old. Additionally, facilitation was not strongest in dry years (contrary to the stress gradient hypothesis) and the nurse canopy cover was not strongly associated with beneficiary metrics. Overall, it is promising for ecological restoration that reestablishing native perennial plants can facilitate native over non-native plants as restoration sites mature.

CITATION: Abella, S.R., Chiquoine, L.P., Balogh, M.A., Taylor, A.J., Munson, S.M. (2023). Do nurse plant effects strengthen over time? Results from 12 years of desert habitat restoration. Plant Ecology, 224, 299-314. DOI: https://doi.org/10.1007/s11258-023-01297-2

Restoring forests to prevent drought mortality

Landscape-scale forest restoration decreases vulnerability to drought in Southwest ponderosa forest

Drought-induced mortality is a threat to worldwide forests, and the forests of the Southwest US are particularly susceptible to tree mortality due to predicted increases in temperature, drier soils, and forecasts with higher density. The Four Forests Restoration Initiative (4FRI) is a large-scale forest restoration effort in northern Arizona that aims to reduce stand basal area. In this study, RAMPS ecologists John Bradford and Caitlin Andrews, along with colleagues from The Nature Conservancy and University of Nevada, Reno, evaluated how ponderosa pine mortality is expected to be influenced by 4FRI restoration activities. Specifically, they modeled drought mortality in three time periods, one contemporary (1970–2010), and two in the future (2020–2059 and 2060–2099) under three restoration scenarios: no thinning, 4FRI thinning, and a BA reduction beyond the 4FRI plan (4FRI-intensive). They estimated mortality using 11 climate models under two emissions scenarios. Without thinning, the model predicted that by mid-century (2020–2059), changes in climate could increase annual ponderosa pine mortality rates by 45–57% over contemporary rates. However, with thinning, mid-century mortality was predicted to remain near or below contemporary rates and these rates are 31–35% (4FRI) and 46–51% (4FRI-intensive) less than the mid-century scenarios without thinning. The study shows that while climate change is likely to increase tree mortality rates, large-scale forest restoration projects, such as 4FRI, have the potential to ameliorate the effects of climate change and keep mortality rates near contemporary levels for decades.

CITATION: McCauley, L.A., Bradford, J.B., Robles, M.D., Shriver, R.K., Woolley, T.J., Andrews, C.A. (2023). Landscape-scale forest restoration decreases vulnerability to drought mortality under climate change in southwest USA ponderosa forest. Forest Ecology and Management, 509(1), 120088. DOI: https://doi.org/10.1016/j.foreco.2022.120088

How to manage changing pinyon-juniper woodlands

New study identifies where land managers can predict climate-driven ecological transformation in Southwest pinyon-juniper woodlands

Pinyon–juniper (PJ) woodlands are major ecosystem across the western US and are potentially susceptible to ecological transformation. However, predicting the fate of woodlands is complicated by species-specific strategies for persisting and reproducing under drought conditions, uncertainty in future climate, and limitations to inferring demographic rates from forest inventory data. In this study, USGS SBSC Ecologists Adam Noel and John Bradford and colleagues from the University of Nevada, Reno and Conservation Science Partners created demographic models to quantify how climate change is expected to alter population demographics for five PJ tree species in the US West and place their results in the context of a climate adaptation framework to resist, accept, or direct ecological transformation. They found that two of the five study species, Pinus edulis and Juniperus monosperma, are projected to experience population declines, and that population declines are more likely to promote ecological transformation in warmer and drier PJ communities of the Southwest. To actively resist ecological transformation, managers may reduce tree density and mitigate competition to favor species that are projected to decline. The authors assessed the effectiveness of this management strategy and classified southwest woodlands into areas where transformation is (a) unlikely and can be passively resisted, (b) likely but may be resisted by active management, and (c) likely unavoidable, requiring managers to accept or direct the trajectory. Their results inform where this adaptation strategy could successfully resist ecological transformation in coming decades and allow for a portfolio design approach across the geographic range of PJ woodlands.

CITATION: Noel, A.R., Shriver, R.K., Crausbay, S.D., Bradford, J.B. (2023). Where can managers effectively resist climate-driven ecological transformation into pinyon-juniper woodlands of the US Southwest? Global Change Biology, 29(15), 4327-4341. DOI: https://doi.org/10.1111/gcb.16756

How are dryland seed banks impacted by fire?

New study addresses this question in four North American desert sites

It is well documented that the recovery of dryland plant communities following fire can be variable, and that the legacies of fire can have long-lasting effects on aboveground plant communities. However, less is known about how dryland soil seed banks are impacted by fire. In this study, USGS SBSC Ecologist Sasha Reed and colleagues at New Mexico State University used a time-since-fire approach to investigate soil seed bank community changes approximately 15 and 30 years after wildfire to determine the influence of microsites (shrub vs. interspace) on seed bank composition. They assessed soil seed bank metrics through greenhouse trials across four North American deserts, including two cold desert sites (Colorado Plateau and Great Basin) and two warm desert sites (Chihuahuan and Sonoran). They found that warm desert seed banks were dominated by annual plants, while cold sites had greater proportions of perennial species, regardless of fire history. In cold desert sites, fire significantly altered seed bank species composition even 30 years after fire, and shrub vs. interspace microsites did not influence seed bank composition. In contrast, seed bank species richness was greater under shrubs in warm deserts. They found that while non-native species were present in all seedbanks, some were particularly abundant in burned sites, suggesting some degree of vulnerability to future disturbances in burned sites, as fire can create amplifying feedback with many non-native plants. Their results highlight strong differences in fires’ relationship with seed banks in warm and cold desert sites that may lend insight into how fire relates to the composition and diversity of the seeds that play a fundamental role in future plant communities.

CITATION: Hosna R.K., Reed, S.C., Faist, A.M. 2022. Long-term relationships between seed bank communities and wildfire across four North American desert sites. Ecosphere (14)3. DOI: https://doi.org/10.1002/ecs2.4398

Establishing big sagebrush seedlings on the Colorado Plateau

Explore the fact sheet for Utah State University Extension

Big sagebrush (Artemisia tridentata) is a foundational rangeland species important to wildlife habitat in the western U.S. Most scientific knowledge of big sagebrush comes from the Great Basin, and researchers know less about how to restore sagebrush on the Colorado Plateau, where soils are different, and conditions are warmer and drier. This fact sheet, co-created by USGS SBSC researcher Mike Duniway and researchers at Utah State University and New Mexico State University, describes research about establishing and restoring sagebrush seedlings in the Colorado Plateau. Through seedling establishment studies in the Utah, they found that planting in coarser, shallower soils in wet years and caging seedlings can improve sagebrush restoration. They also note that digital soil mapping could be used to identify and prioritize areas with soil textures and depths that are best for establishing sagebrush seedlings.

CITATION : Veblen, K.E., Thacker, E., Larese-Casanova, M., Nehring, K., Duniway, M., Brungard, C. (2023). Establishing big sagebrush seedlings on the Colorado Plateau [Fact sheet]. Utah State University Extension.

RAMPS is a program of the USGS Southwest Biological Science Center located in Flagstaff, AZ

RAMPS engages stakeholders within the U.S. Department of the Interior, other federal and state agencies, Tribal governments, and on private lands to provide guidance and support for effective restoration strategies across the southwestern U.S. The RAMPS network consists of over 500 individuals representing 50+ agencies, organizations, and universities working together to increase land productivity and reduce threats posed by environmental hazards. 

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