Applying ecological treatments to boost yields among restoration target species of seed production areas

Progress report for GNC19-293

Project Type: Graduate Student
Funds awarded in 2019: $14,942.00
Projected End Date: 10/29/2022
Grant Recipients: University of Illinois at Urbana-Champaign; University of Illinois at Urbana-Champaign
Region: North Central
State: Illinois
Graduate Student:
Faculty Advisor:
Dr. Jeffrey Matthews
University of Illinois at Urbana-Champaign
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Project Information

Summary:

Title: Applying ecological treatments to boost yields among restoration target species of seed production areas

Ecological restoration seeks to repair or assist the recovery of damaged or degraded ecosystems and yields benefits to society. Seed production areas (SPAs), which are plantings of wild plant species that apply agricultural and horticultural practices, are critical to supply these seeds for ecological restorations. SPA managers face challenges when cultivating wild plant species, leading to financial difficulties and unreliable seed supplies. Thus, restoration practitioners are commonly restricted by expensive or unavailable seed. SPA management techniques must be improved to boost seed yields to benefit stakeholders and facilitate ecological restorations. A common method to boost yields is to use chemical fertilizers similar to traditional agricultural techniques. Fertilizer addition has potential negative consequences such as nutrient runoff and promoting weed invasion, however. A promising technique is inoculation with arbuscular mycorrhizal fungi (AMF). AMF are soil fungi which associate with plant roots, providing water, nutrients, and pathogen defense in exchange for plant carbon. Recent studies suggest that soil inoculation with AMF could be an alternative and beneficial management technique that boosts plant growth. Yet, the value of AMF inoculation in commercial settings has not been evaluated.

To study SPA management, I will test nutrient addition and AMF inoculation strategies in experimental SPAs. Using a randomized block design, I will determine how the treatments affect seed yields and managerial input for three restoration species in two study sites across three growing seasons. Learning outcomes of the project include increasing knowledge of SPA management techniques, and generating awareness of the potential of AMF as a sustainable management strategy. Long-term action outcomes include implementation of production techniques which will increase seed yield in SPAs and provide a more reliable source of native plant seed for ecological restorations. I will evaluate the outcomes of this project by a combination of personal interaction with stakeholders at targeted conferences, as well as a follow-up survey of a technical report that I will send directly to producers in the native plant industry. My project will enhance the quality of life for SPA managers in the native plant industry, improve seed supplies imperative for restorations, and make this seed production more sustainable.  

Project Objectives:

My outcomes will target stakeholders in the native plant nursery, particularly native seed producers. This project will create critical knowledge about SPA management techniques for native growers. Such knowledge would improve the abilities of managers to reliably produce their crop. Results could encourage native growers to boost yields using sustainable inoculation techniques rather than fertilizer addition. It will promote a greater awareness about the value of soil manipulation through arbuscular mycorrhizal fungal inoculation. My participating stakeholders will apply both methods to their experimental SPAs. Long-term action outcomes include implementation of production techniques which will increase seed yield in SPAs and provide a more reliable source of native plant seed for ecological restorations

Research

Materials and methods:

2021 Field Season Summary

Seed production areas (SPAs) are important to secure seed supplies for ecological restoration. Despite this importance, management practices to boost SPA yields are not well developed. The objectives of the GNC19-293 project are to study the agronomic production of native prairie wildflowers using arbuscular mycorrhizal fungi (AMF) inoculation and fertilizer application. I established experimental SPAs across three sites in a complete randomized block design, applying the treatments factorially to four prairie wildflower species. I concluded my second year of data collection. Plant survival varied across sites and species, with minor to modest attrition (average 8.2% loss) of study plant individuals. One site, Barefoot Nursery, had substantially smaller plant size and seed production relative to other sites. In 2021, a total of 135 lb of raw seed was harvested, with an estimated value of ~$6,500, assuming 1/3 of harvested material was pure seed. I did not find evidence that per capita seed yield increased with fertilizer or AMF addition. These findings were reinforced by estimates of plant size since there were also no significant differences among treatments. I discuss how potential treatment effects could be obscured by averaging, random field variation, or favorable SPA growing conditions. Seed was distributed to stakeholders for use in restoration or commerce. I hosted another volunteer field day with the Boy Scouts of America in August at the Lake of the Woods site and gave a presentation about the project to the Society for Ecological Restoration Midwest-Great Lakes Chapter. This report details the progress made in the second of three growing seasons of the project and provides preliminary data analyses and discussion of the project going forward. 

Background

To perform ecological restorations, many practitioners use revegetation to assist ecosystem recovery, particularly using seeds due their efficiency to revegetate areas (Brudvig 2011). Seed production areas (SPAs) are critical to supply these seeds for ecological restorations (Broadhurst et al. 2016). SPAs are plantings of wild species which are grown using agricultural and horticultural practices to maximize seed production (Broadhurst et al. 2016). They are considered a viable method to yield seed for restorations when wild seed sources are unavailable.

Despite the role of SPAs in ecological restoration, stakeholders in the native plant industry face severe business challenges. SPA managers have described rigorous labor requirements, poor managerial knowledge, and unreliable seed outputs of their native crops as major obstacles to efficient production (Jones and Young 2005). Likewise, institutional support for SPA managers is low and research regarding SPA management is scarce (Merrit and Dixon 2011). These obstacles can reverberate to other stakeholders. For example, prairie restorationists frequently claim that they are limited by inadequate seed availability and expensive seed prices (Rowe 2010). Restorations are also becoming larger in size and provoking seed shortages in restorations (Broadhurst et al. 2016). Hence, there is a substantial need to improve SPA management and yields (Merrit and Dixon 2011; Broadhurst et al. 2016).

Inoculation with indigenous arbuscular mycorrhizal fungi (AMF) is a promising management strategy to improve SPA yields. AMF are a broad group of soil fungi which penetrate plant roots and generally provide nutrients and water in exchange for an energy source (Berruti et al. 2016). The AMF relationship can benefit a plant by enhancing the plant’s resource acquisition, buffering it from stresses (e.g., drought and herbivory), and even defending against soil pathogens (Berruti et al. 2016). Recent evidence suggests that many restoration target species have substantial growth benefits when they associate with AMF inocula that are indigenous to prairies in experimental settings (Koziol and Bever 2017; Bauer et al. 2017). AMF inoculum was found to improve survival of planted plugs and promote early flowering of prairie restoration target species (Koziol and Bever 2017). Although the positive potential of AMF inoculation to SPAs has been identified, its value in commercial settings has yet to be evaluated.

Alternatively, SPA managers could apply chemical fertilizers to boost SPA yields, which is often done in the industry (Dunne and Dunne 2003). However, fertilizers may be a poor management choice in SPAs. Fertilizer may not be conducive to the ecology of many native target crops. Many SPA crops are slow growing and have growth traits less suited for the quick acquisition of labile soil nutrients (Bauer et al. 2017), in contrast to traditional agricultural species.

For SARE GNC19-293, I created experimental SPAs which tested the effects of AMF inoculation and fertilizer addition as management strategies. This report updates on the progress of the project, including the project’s methods, preliminary findings from the 2020-2021 field season, and outreach. Furthermore, I detail the future of the project.

Methods

Field site descriptions

Three sites were used for the project, representing different stakeholders for SPAs (Fig. Methods-1): Barefoot Nursery & Restoration (Springfield, IL, and hereafter, “Barefoot”), Heritage (Champaign, IL, and hereafter, “Heritage”), and Lake of the Woods Forest Preserve (Mahomet, IL, and hereafter, “LOTW”). These locations represent a private enterprise, a local organization, and a regional conservation organization, respectively.

Figure Methods-1: Locations of the three field sites of experimental SPAs in Illinois.

Barefoot is a private nursery which specializes in native plants, including existing plots for seed production. The site consists of small-scale infrastructure for growing and producing seed mixes. The SPA at this site was established on a 1-acre section of a corn-soy farm field, which was adjacent to the nursery. Soils at the site range from sandy loam to pure sand due to historical deposition from the nearby Sangamon River. Thus, some sections in the SPA appear unusually nutrient-poor, as well as prone to heating and desiccation. The Heritage location is former turf grass managed by the Champaign Park District (Fig. Methods-2). The site is marginal property for the Park District, with low pedestrian and recreational traffic. The site is flanked by a prairie restoration to the east, and Copper Slough to the west. The soils are Drummer silty clay loam, and have a low weed seed bank. Growing conditions at Heritage seem the least stressful (e.g., high quality soil, high water retention). LOTW is a nature preserve managed by the Champaign County Forest Preserve District (CCFPD), consisting of a matrix of woodland, prairie, and savanna habitats. The SPA was established on an acre of old field adjacent to the popular Buffalo Trace Bike Trail. Previously, the site was dominated by Bromus inermis (smooth brome), Trifolium pratense (red clover), and ruderal species. Soils at the SPA are Dana silt loam, and appear to be of intermediate growing quality when compared to Barefoot and Heritage.

fig.2methods

Figure Methods-2: Heaven on Earth, Heritage SPA during peak blooming of Echinacea pallida in June, 2021.

SPA preparation and experimental design

Experimental SPAs were created using a randomized block design, with a 2x2 factorial treatment combination, with AMF inoculation and fertilizer addition as treatments (Fig. Methods-2). Each block was 32 ft x 43 ft and consisted of 4 25-ft rows. To prevent treatment spillover, buffers between each row were 6 ft; buffers between rows within blocks were 7 ft (Fig. Methods-2a). Buffers were seeded with turfgrass at Barefoot and LOTW due to the lack of suitable vegetation at these sites.

Figure Methods-2: The dimensions and experimental design of the SPAs at the three sites. A) A visual representation of the dimensions of each block and its components. B) An example of the experimental design, showing randomized treatments within two example blocks. Each block has randomized positioning of the study species within each row.

SPAs were established in early April 2020 by using 4’ Dewitt Sunbelt weed barrier fabric to smother existing vegetation (Figs. 3-4).

Study species descriptions, cultivation, and field transfer

I chose four study species: Asclepias tuberosa (butterfly weed), Echinacea pallida (pale purple coneflower), Eryngium yuccifolium (rattlesnake master), and Parthenium integrifolium (wild quinine). These species were selected because 1) they are herbaceous flowering target species in restorations and are valuable for use in USDA programs such as the Conservation Reserve Program and CP-42 pollinator plantings (National Conservation Practice Standards 2015), 2) they were also previously shown to have positive growth responses to indigenous AMF treatments in experimental settings (Koziol et al. 2017).

I purchased seed of the four study species in January 2020, from Prairie Moon Nursery (Winona, MN). Prairie Moon Nursery sells sourced seed (i.e., local ecotype) from a network of producers throughout the Midwest. All seed was cold moist stratified in double-sterilized sand for 60 days.

I applied the nurse plant method for inoculation. This method pre-infects seedlings or plugs prior to field establishment, which can boost inoculum survival and have infected plants act as nuclei to nearby plants (Koziol et al. 2017). In late March, 2020, seeds were sown into flats containing a mixture of 50-50 sand and general-purpose soil mix (1:1:1 soil/peat/perlite), which was double sterilized using steaming. There were one to two rest days in between each sterilization event. After germination and the appearance of cotyledons, seedlings were transferred to 72-cell growing trays. Thereafter, for all the study species, half of seedlings were put into -AMF growing trays (60-40 double-sterilized sand/potting soil mixture), while the other half were transferred to +AMF growing trays. +AMF growing trays consisted of 45-45 double sterilized sand/potting soil mixture, and 10% by volume of MycoBloom AMF. 10% of AMF mixture by volume is considered a liberal volume by MycoBloom instructions. I used the 50-50 sand/potting soil mixture as the base in growing trays in order to increase nutrient stress to promote +AMF seedling inoculation. Because AMF infection occurs over 2 weeks, seedlings were grown for 4-6 weeks before field transfer to promote root infection. Seedlings were grown in temperature-controlled conditions (24°C) at the University of Illinois Agricultural and Consumer Sciences Plant Care Facility (40° 6' 7" N, 88° 13' 26" W).

Most plugs were planted in-field between late April through June in Heritage and LOTW. Plugs were planted in late June and early July at Barefoot to allow the grass seed in the buffers to stabilize the soil. At each site, a particular species was always planted on a single day to minimize priority effects. Dead seedlings were replaced within 2 weeks of the initial establishment to have more complete rows, while avoiding substantial time elapsed to lead to priority effects. In each row, 6 plugs of each species were planted per row, totaling 24 plants per row across the four study species. Plugs were planted by staggering at a 1.4-ft distance (Fig. Methods-2a); plants were staggered to avoid overcutting the center of the fabric. The fabric was cut by a 15-cm “X” in the plastic to transfer the plugs.    

Field management

Fig.3

Figure Methods-3: Post-mowing appearance of Heritage. Picture was taken in late July, 2021. Note the orange flowering A. tuberosa in the background.

Throughout the growing season, buffers within the blocks were mown approximately once every 10 days (Fig. 3). Rows were weeded as needed, generally monthly for Heritage and Barefoot, and biweekly for LOTW. In August, 2020, I began fertilization treatments across all +nutrient rows in the three sites. The fertilizer used was Peters Excel 15-5-15 (NPK) fertilizer; a high N:P ratio was sought out because P fertilization is less important with respect to seed production (Ken Fromm, personal communication). Fertilization treatments consisted of, and will consist of for the duration of the experiment, adding 350 mL at 125 ppm (N) concentration to each individual plant within the +fertilizer rows.

Data collection in fall, 2021

fig4afig.4b

Figure Methods-4: Lush growth of P. integrifolium (left) and A. tuberosa (right) at Heritage +fertilizer rows in August 2021. Both plants pictured are ready for data collection, which included leaf area estimates and seed collection, if applicable. Note the brown seed heads of P. integrifolium in the left, suggesting this individual is ready for seed harvest.

Like last year, at each site I determined each individual plant’s survival, flowering status, and size (Fig. Methods-4). Size was assessed by measuring a plant’s height and its estimated leaf area. For each plant, leaves were subjectively counted as “small,” “medium,” or “large” based on the species. For each species, I estimated the area of each size class by averaging twenty samples of each species-leaf size combination. Leaf size class counts were then multiplied by the calculated average, and then summed for each plant. Seed was hand-harvested by row. Seeds were weighed in November 2021. For plant size estimators and seed yield, I averaged the values across species and within rows, yielding mean per capita leaf area and seed production.  

I calculated survival for each site-species combination, as well as the percent change for each combination between 2020 and 2021. For each site-species-treatment combination, I used Kruskal Wallis tests to determine if there were significant differences in log-transformed per capita seed yield (g) and log-transformed estimated leaf area (cm2) among treatments. Kruskal Wallis tests were used as alternatives to ANOVAs due to less restrictive statistical assumptions. I compared per capita seed yields across sites and within species using Wilcoxon rank-sum tests. All data analyses were conducted using R v. 4.0.2 (R Core Team 2020).

References

Bauer J.T., Koziol L., Bever J.D. 2017. Ecology of Floristic Quality Assessment: testing for correlations between coefficients of conservatism, species traits, and mycorrhizal responsiveness. AoB Plants: plx073.

Berruti A., Lumini E., Balestrini R., et al. 2016. Arbuscular mycorrhizal fungi as natural biofertilizers: Let’s benefit from past successes. Frontiers in Microbiology 6: 1559.

Broadhurst L.M., Jones T.A., Smith F.S., et al. 2016. Maximizing seed resources for restoration in an uncertain future. BioScience 66: 73-79.

Brudvig L.A. 2011. The restoration of biodiversity: Where has research been and where does it need to go? American Journal of Botany 98: 549-558.

Dunne R.A., Dunne C.G. 2003. Trends in the Western native plant industry since 1990. Native Plants Journal 4: 88-94.

Gibson-Roy P. 2018. Restoring grassy ecosystems- Feasible or fiction? An inquisitive Australian’s experience in the USA. Ecological Management and Restoration 19: 11-25.

Jones T.A., Young S.A. 2005. Native seeds in commerce: More frequently asked questions. Native Plants Journal 6: 286-293.

National Conservation Practice Standards. 2015. Conservation cover (Ac.): Code 327. (http://www.gfseedco.com/uploads/3/4/9/2/34921431/conservation_cover_il327_october_2015_final.pdf)

Koziol L., Schultz P.A., Bever J.D., et al. 2017. User Manual: A practical guide to inoculation with arbuscular mycorrhizal fungi in ecological restoration. SERDP Project RC-2330.

Merrit D.J., Dixon K.W. 2011. Restoration seed banks—A matter of scale. Science 332: 424-425.

R Core Team. 2020. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/.

Rowe H.I. 2010. Tricks of the trade: Techniques and opinions from 38 experts in tallgrass prairie restoration. Restoration Ecology 18: 253-262.

Zinnen J., Broadhurst L.M., Gibson-Roy P., Jones T.A., Matthews J.W. 2021. Seed production areas are crucial to conservation outcomes: benefits and risks of an emerging restoration tool. Biodiversity and Conservation 5: 1233–1256.

Research results and discussion:

Preliminary findings

Here, I present some preliminary analyses of the data from the 2020-2021 field seasons. This includes survivorship among the study sites, and comparisons between plant size and per capita seed yield.

fig.5

Figure Results-1: Survival of plugs planted in 2020. Above each bar plot is the % change between 2020 and 2021. Note that P. integrifolium at LOTW increased, likely due to dormant plants being counted as dead in the 2020 field season or reseeding into empty cells.

Survival varied between the sites, partially reflecting the legacy of the 2020 season (Fig. Results-1). Total percent survival was highest in Barefoot, followed by Heritage. LOTW had poor survival of plugs due to intense herbivory during 2020. Although survival was highest at Barefoot, note that this finding is misleading since many plants merely persisted and failed to grow to appreciable sizes. Across sites, E. pallida had the highest survival (~85%), followed closely by P. integrifolium (82.5%). A. tuberosa and E. yuccifolium both had lower survival overall at <80%.

There was substantial attrition in plants for about half of the site-species combinations between 2020-2021. There was an average 8.2% decrease in survival between 2020 and 2021. Counted P. integrifolium survival increased in survival in 2021 by 21% compared to 2020. This was likely due to two artifacts: 1) plants in 2020 counted as dead were dormant, or 2) some plants counted as surviving in 2021 may have been sprouts from 2020 seeds.  

Seed yields were substantial in the 2021 field season (Table 1). During 2021, we harvested ~135 lb of raw seed mass (including chaff) between E. pallida, E. yuccifolium, and P. integrifolium, which was 43, 33, and 59 lb, respectively. Although nearly 2/3 (64%) of A. tuberosa individuals flowered during the 2021 season across all sites, only a handful produced viable seed pods, so we only collected leaf area estimates for this species. Raw seed mass substantially varied among sites (Table 1): Heritage had the highest yield (~81 lb), followed by LOTW (51 lb); Barefoot yields were extremely low (~3.4 lb) due to the stressors on site.  

Site

Spp.

Raw mass (lbs)

Pure seed weight estimate (lbs)

*Estimated value ($)

Heritage

A. tuberosa

 

0.0

0.0

$0.00

 

E. pallida

 

21.3

7.1

$852.00

 

E. yuccifolium

 

16.9

5.6

$672.00

 

P. integrifolium

42.7

14.2

$2,556.00

 

 

 

Sum: 80.9

Sum: 26.9

Sum: $4,080.00

 

LOTW

A. tuberosa

 

0.0

0.0

$0.00

 

E. pallida

 

21.4

7.1

$852.00

 

E. yuccifolium

 

15.2

5.1

$612.00

 

P. integrifolium

14.2

4.9

$882.00

 

 

 

Sum: 50.8

Sum: 17.1

Sum: $2,346.00

Barefoot

A. tuberosa

 

0.0

0.0

$0.00

 

E. pallida

 

0.4

0.1

$12.00

 

E. yuccifolium

 

1.0

0.3

$36.00

 

P. integrifolium

2.0

0.7

$126.00

 

 

 

Sum: 3.4

Sum: 1.1

Sum: $174.00

 

 

 

TOTAL: 135.1 lbs

 

TOTAL: 45.1lbs

 

TOTAL: $6,600.00

Likewise, the estimated monetary value of the seed varied between sites. Heritage seed was estimated at >$4,000.00; this was due to high yields of P. integrifolium, combined with good yields for the other two species due to favorable growing conditions, low weed competition, and excellent survival. Likewise, when organized across sites and species, per capita seed production in 2021 was always significantly higher than the 2020 field season (Fig. Results-2; p<0.001).

fig.6

Figure Results-2: Comparisons of per capita seed yield between the 2020 and 2021 field seasons for A) E. pallida, B) E. yuccifolium, and C) P. integrifolium. Rows and thus treatments were pooled for this figure for simplicity. *** indicates a significant difference (p<0.001) in per capita seed production between the years within the listed site. Some that some rows had no seed yield for 2020 (viz., Eryngium in B).

There was little evidence for treatment effects across the study sites and species (Fig. Results-3). At Heritage and LOTW, there were no significant differences in per capita seed production among treatments for all three species (df=3, p>0.5 for Heritage; df=3, p>0.2 for LOTW). At Barefoot, there were no significant treatment differences for E. pallida or E. yuccifolium (df=3 and p>0.15). However, at Barefoot, there was a marginally significant difference in per capita seed yield for P. integrifolium (df=3; p=0.07), which appeared to be due to well-performing +nutrient/+AMF rows.

fig.7

Figure Results-3: Log-transformed per capita seed yields per row (n=8) of three study species across three study sites and four treatments for 2021. For species, “E. pall.,” “E. yucc.,” and “P. int.” stand for E. pallida, E. yuccifolium, and P. integrifolium, respectively. Treatment codes are “C” (control), “+N” (fertilizer addition), “+M” (AMF addition), and “+NM” (fertilizer and AMF addition). “ns” means there was no significant difference between treatments (p>0.1) in a Kruskal Wallis test; the gray period indicates a marginally significant treatment difference for P. integrifolium at Barefoot.

Like last year, using leaf area as a proxy, estimated per capita leaf area closely matched the negative findings of per capita seed yields (Fig. Results-4). There was some indication that treatments led to different per capita leaf areas for P. integrifolium and E. pallida at Barefoot; however, these differences were still not significant (p=0.11 for both). There was a similar nonsignificant difference in A. tuberosa at Barefoot (p=0.15). There were no significant treatment effects of per capita leaf area for E. yuccifolium (p=0.81) at Barefoot. At Heritage and LOTW, there were no significant differences in per capita leaf area among treatments across all four species (p>0.22).

fig.8

Figure Results-4: There were no significant differences among log-transformed estimated leaf areas across the species and study sites. For species, “A. tub.,” “E. pall.,” “E. yucc.,” and “P. int.” stand for A. tuberosa, E. pallida, E. yuccifolium, and P. integrifolium, respectively. Treatment codes are “C” (control), “+N” (fertilizer addition), “+M” (AMF addition), and “+NM” (fertilizer and AMF addition). “ns” means there was no significant difference between treatments (p>0.1) in a Kruskal Wallis test. Leaf area estimates were calculated by multiplying and then summing counts of leaf size classes for each species based on averaged leaf sizes (cm2) for each species.

However, upon further exploration of the data, some of these measurements were clearly influenced by the number of survivors per row. Specifically, measurements for rows with fewer surviving plants suggested that the plants tended to be larger on average. For example, Fig. Results-5 shows the relationship between per capita seed output and number of individuals per row for P. integrifolium. The survivor-leaf area relationships were even more pronounced and appeared to decline to an asymptote with increasing survivors (data not shown). These trends reinforce my speculations that per capita measures using means may be problematic, and could be due to release from competition, or a lower probability of sampling “straggler” individuals (see Prospective section below).

fig.9

Figure Results-5: An example of context dependency of per capita measures. Shown here is the linear decline of per capita seed mass of P. integrifolium at Heritage, suggesting that rows with fewer surviving individuals perform better on average. Each data point represents the per capita seed mass of a row (n=32).

Discussion

During 2020-2021, I did not find substantial evidence for treatment effects of fertilizer or AMF addition. Although there may yet be identifiable treatment effects in these data, the evidence hitherto is not overwhelming or obvious. What could be the result of these counterintuitive findings? I suggest these null results could be due to confounding variables, as well as the unique ecology of SPAs.

First, I highlighted several challenges of the response variables, particularly with respect to per capita measurements. For example, per capita measures are sensitive to nominally surviving but small individuals, as well as latently influenced by per-row survival. Additional data exploration will be necessary to determine if the null results are robust with different response variables related to seed production and plant size. Secondly, SPAs themselves have unique ecologies. Zinnen et al. (2021) describe how plants in SPAs have an enhanced fitness potential due to decreased or absent stressors relative to wild conditions. Perhaps larger individuals may approach an asymptote of size or seed output in SPAs, or the treatment effects may be less important relative to random block environmental variation.

Although AMF did not appear to increase seed production or leaf area, this finding has several explanations. Most importantly, AMF treatments may be overridden by background AMF communities in the soil. Perhaps the conservative study species are capable of productive associations with many AMF communities (i.e., they could have low fidelity to specific AMF species). In a study of remnant-restricted species in Australia, Gibson-Roy et al. (2014) found, contrary to their expectations, that previously disturbed communities had similarly abundant AMF to high-quality remnant ones.

References

Gibson-Roy P., McLean C., Delpratt J.C., Moore G. 2014. Do arbuscular mycorrhizal fungi recolonize revegetated grasslands? Ecological Management and Restoration 15: 87-91.

Wyatt R. 1976. Pollination and fruit-set in Asclepias: a reappraisal. American Journal of Botany 63: 845-851.

Zinnen J., Broadhurst L.M., Gibson-Roy P., Jones T.A., Matthews J.W. 2021. Seed production areas are crucial to conservation outcomes: benefits and risks of an emerging restoration tool. Biodiversity and Conservation 5: 1233–1256.

Participation Summary
3 Farmers participating in research

Educational & Outreach Activities

1 On-farm demonstrations
1 Tours
1 Webinars / talks / presentations
1 Workshop field days

Participation Summary:

Education/outreach description:

Outreach

fig.10

Figure Outreach-1: The interpretative sign in front of the LOTW site provides information to bike trail patrons. The description describes the project and the broader relevance of ecological restoration and SPAs.

The physical locations of the study sites were conducive to informal outreach. Public outreach and accessibility were one of the primary reasons to expand the project to the LOTW location, where both experimental and volunteer SPAs are adjacent to a bike trail popular among Champaign County residents. Over the season, I spoke to several patrons about the project between the Heritage and LOTW sites, including some teachers at nearby Mahomet High School. Anecdotally, I have noticed the SPA fencing is a popular stretching site for Mahomet cross country runners. The CCFPD has erected an interpretive sign at the site, which describes SPAs and the project with respect to prairie restorations at LOTW (Fig. Outreach-1).

In April 2021, I gave a presentation for this project at the online 2021 Society for Ecological Restoration Midwest-Great Lakes Chapter Annual Meeting. Here, I focused on the LOTW site, and emphasized the combination of experimentation and volunteerism occurring here.

Fig.11

Fig. Outreach-2: A volunteer field day for the Boy Scouts at LOTW in June, 2021. Volunteers planted P. pilosa ssp. sangamonensis and other prairie forbs under a tent due to the heat.

Additionally, I managed another volunteer day at the Lake of the Woods site with ~8 masked Boy Scouts on June 12, 2021 (Fig. Outreach-2). Scouts assisted with planting plugs in an additional, volunteer seed production section. Like last year, I gave a short lecture talking to the Scouts about seed production areas, their utility to ecological restoration, information about the study species, the status of the site (Fig. Outreach-3), and the importance of plant biodiversity. I was working closely with an intern from the University of Illinois IGNITE Undergraduate Research Program, who received valuable research and field experience from the project.

fig.12

Figure Outreach-3: Volunteer plots at the LOTW of flowering Phlox pilosa ssp. sangamonensis in May 2021. This taxon is a state-endangered and endemic subspecies of prairie phlox planted by last year’s Boy Scout field day. Seed harvested in 2021 is currently cold-moist stratifying and awaiting approval for planting among stakeholders’ properties (viz., LOTW and Grand Prairie Friends).

The 2022 field season will be the final year of data collection, which is intended to be a repeat of the methods of 2021. However, I am planning an outreach technical report for stakeholders in the native plant industry. This will occur during the second half of 2022 and be an overview of the native plant industry in the Midwest; I will include some details of my project therein. Furthermore, my advisor and I plan to partner with the University of Illinois Agricultural Extension to create and distribute the report.

I will be speaking with the stakeholders of the project this year about continued management and/or expansion of the experimental SPAs as I complete my graduate studies (Fig. Outreach-4).

fig.14afig.14b

Figure Outreach-4: Early season appearances of the SPA. Left: budding plants at LOTW in early April. Right: robust growth of E. pallida (pictured in the foreground) in late-April, 2021 at Heritage.

Project Outcomes

1 Farmers changed or adopted a practice
1 Grant received that built upon this project
1 New working collaboration
Project outcomes:

This project is one of the first of ites kind to scientifically study seed production area management. During the 2021 field season, I continued the project by working with stakeholders, collecting data, and harvesting seed for use in commerce and restoration. Thus far, contrary to my expectations, I have not detected significant treatment effects during 2021. Null findings are still scientific findings nonetheless, so a resulting publication for this project could be to highlight how basic SPA management practices themselves (e.g., plastic rows, low density plantings) and random field variation may override specific treatment effects. If I do not find treatment effects for fertilizer, this may suggest that fertilizer addition is unnecessary for some conservative native plant species.

This project has had several social benefits. Specifically, my outreach at LOTW has exposed young minds to ecological restoration and the native plant industry. Most importantly, however, the project has provided my stakeholders native seed with substantial market value. For the Champaign County Parks District, I was told my yields were helpful due to a below average in situ seed harvesting season. Thus, although the hypotheses of this project have not met expectations, the pragmatic value for the stakeholders has been impressive. I suggest this project has been a demonstrative "proof-of-concept" for using SPAs on marginal lands, and I have been in early discussions about the future of the SPAs after my graduate studies. 

Knowledge Gained:

Prospective

Surprises and challenges of 2021 field season

There were several challenges, changes, and shortcomings of the 2021 field season. One minor problem is the continuous attrition of plants in the experiment. Some individuals appeared to die between winter, 2020 and spring, 2021; I also noticed others rotted or died after emerging throughout the spring and summer. The LOTW site has been particularly problematic in both field seasons due to intense herbivory and weeds; this could explain the discrepancy between P. integrifolium survival recorded in 2021 versus 2020. 

Another challenge was the lack of consistent seed production for A. tuberosa. Most flowers failed to develop seeds, and the vast majority of pods that did develop consisted of nonviable seed. At the end of the season, only a handful of pods produced viable seeds. This may have been due to infestations of milkweed bugs (Oncopeltus spp.) and aphids (Aphis nerii), which commonly swarm developing milkweed pods. Furthermore, Asclepias species have complex pollination requirements, and have unusually intricate floral structures (Wyatt 1976) compared to the other study species. Thus, although this species is an excellent restoration target species, studying its seed production in scientific field settings may be complicated by these factors. For the 2022 season, we will only measure size (e.g., height and leaf size estimates) to stay consistent between the years.

A major finding of my exploratory data analysis for the report is that the number of survivors in rows apparently has a strong effect on per capita measures (e.g., Fig. Results-5). I suspect this is due to two reasons. First, a few surviving individuals in a row are likely to be larger due to limited competition from intraspecific neighbors. Secondly, and more importantly, if there are more individuals in a row, there is a higher chance we sampled an individual that is smaller, or only marginally persisting. Anecdotally, I noticed that many plants survive and persist, but appear stunted. This was true across all four species, but especially P. integrifolium and A. tuberosa. These “straggler” individuals merely cling to life, and likely considerably decrease the per capita response variables. This represents a confounding variable and will complicate analysis. Some approaches include incorporating survival into a linear mixed effects model as a covariate, rerunning analyses with medians instead of means, or using the number of flowering versus total individuals. Thus, my impression of this project is that it is successful at producing valuable goods and services to stakeholders, but the data are messy and will require considerable and additional cleaning and inspection before final analyses.  

Finally, the largest challenge of the field season was the simple logistical requirements during late summer and early fall. Surviving plants were much larger, making leaf area estimates time-consuming, tedious, and difficult. Once this process started in late August (first for E. pallida), leaf and height measures were conducted almost daily until early November.

One positive change in 2021 was the reinforcement of the deer fences at Barefoot and LOTW; fence posts were reinforced with 7-12 foot metal posts. Unlike the 2020 field season, deer encroachment into the plots (while not completely nullified) had substantially decreased, and herbivory had decreased. I conjecture this was due to improved fencing, plus mature plants being less palatable or attractive to deer or rodents.

The seed has been turned over to the Champaign Parks District and CCFPD (Fig. Knowledge Gained-1).  to be used in local ecological restorations. Mike Dobron (Barefoot Nursery) was also given seed from his site, likely to sell it or include it into commercial seed mixes for the Springfield, IL area.

Fig.13

Fig. Knowledge Gained-1: Delivering seed from Heritage to the Champaign County Parks building for storage and processing post-weighing. Note each bag is likely contains >$300.00 worth of prairie seed.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.