Searching for Seeds: An Urban Experiment in Native Plants for Ecological Restoration

Written by Li Zhuang and Bingqin Shan

China’s ecological restoration sector is expanding rapidly, however sourcing native plant materials remains a major challenge. While government-led greening projects operate at massive scales, the market for seeds and seedlings remains dominated by ornamental and exotic species. Commercial nurseries prioritize producing high-yield, visually appealing, and fast-selling plants. Peng, who works at a large nursery in the Yangtze River Delta managing millions of plants across Zhejiang and Jiangsu provinces, explains: “Nurseries prioritize uniformity and market demand. Biodiversity doesn’t sell”. Although some project developers and designers increasingly recognize the need for native species, their requests rarely create stable demand, so nurseries see little incentive to diversify.

Current propagation practices deepen the gap. Most plants in the nurseries are produced through cuttings or tissue culture to preserve desirable traits, creating vast clonal stocks with low genetic diversity that are vulnerable to pests and unsuitable for restoration. Seed propagation is rare in commercial nurseries, and when it occurs, genetic origin of these seeds is rarely traceable and often limited to just a few parent trees. Large nurseries usually collect seeds from their own cultivated stock, restricting the gene pool to plants already in the nursery. Smaller nurseries, lacking the time and resources to wait for trees to mature and bear fruit, often collect seeds from the wild instead. However, these collections usually come from a single site, without consideration for the ecological impact of harvesting or the need to preserve genetic diversity. As Chinese regulations do not require suppliers to disclose seed sources, this challenge remains unsolved. Meanwhile, national research institutions maintain extensive germplasm collections, but these resources remain confined to scientific use rather than practical restoration. This fragmented supply chain fails to deliver genetically diverse, locally adapted plant material at scale.

Urbanization compounds the problem. Germplasm surveys and collections for seed banks are often concentrated in protected areas with relatively good natural conditions, leaving highly urbanized areas underrepresented. However, many restoration projects in the Yangtze River Delta are located in highly urbanized areas. In this case, many important native plant species have become critically endangered or locally extinct, even in nearby rural or mountainous areas. This situation increases the difficulty of sourcing native seeds for restoration. Taoran Guo, founder of Forest City Studio, argues that collecting seeds from these remnants is essential to preserve the genetic diversity of urbanized regions. Despite this urgency, such plant populations are typically small and scattered, making systematic collection and propagation even more difficult.

Forest City Studio, a social enterprise based in Shanghai, began collecting native seeds after failing to source suitable plant material for their local restoration projects. Each year during seed maturation, they conduct multiple rounds of collection across the city, prioritizing sites with minimal disturbance and confirmed historical presence. To date, they have gathered seeds from 46 wild annual herbaceous species, 38 perennial herbaceous species, and 23 species of trees and shrubs.

Figure 1 A member of Forest City Studio collecting Patrinia villosa seeds.

Figure 2 Native plant seeds collected by Forest City Studio.

Urban conditions make the collection exceptionally difficult. Best practices recommend collecting from large, genetically diverse populations and preventing overharvesting to protect wild populations (Basey et al. 2015). However, in Shanghai, remnant habitats often contain only a handful of individuals. One case involved Ottelia alismoides, a native aquatic plant once common in Shanghai’s wetlands. It depends on clear, flowing streams and ditches, habitats now lost to channel hardening and urbanization. Guo’s team initially found only one individual in an irrigation canal in Cenbu Village, Qingpu District in Shanghai, and later discovered ten more in nearby villages. However, these ten grew closely together, making it highly likely that they originated from a single individual, which means their genetic diversity could be very limited. “With habitats gone, finding even one plant is considered lucky,” notes Guo.

Figure 3 Ottelia alismoides, now listed as a national Class II protected species. After collection, it is propagated by Forest City Studio for use in small-scale wetland restoration projects.

Figure 4 Ottelia alismoides was collected by Forest City Studio in Qingpu District, Shanghai. The plant grows in farmland irrigation ditches, habitats that are often subject to human disturbance.

The constraints do not end with seed collections. Forest City Studio’s propagation process is limited by both manpower and space, which often results in compromising genetic diversity. In practice, the team selects only early-germinating seedlings for cultivation, discarding trays containing ungerminated seeds. This approach overlooks the ecological value of staggered germination, which allows plant populations to hedge against environmental risks such as late frost or predation (Basey et al. 2015). Although preserving late-germinating seeds could preserve genetic diversity, doing so requires additional labor and time with uncertain yields. As a result, part of the genetic diversity within wild seed populations is lost before restoration even begins.

Figure 5 Seeding and seedling cultivation of native plants at Forest City Studio.

Preventing cross-pollination among seedlots in production is another challenge. Although the suggested separation distances are at least 100 meters for animal-pollinated species (Van Rossum and others 2011) and over 200 meters for wind-pollinated species to prevent hybridization (Robledo Arnuncio and Gil 2005). In reality, small-scale restoration organizations, like Guo’s nursery, lack the space, labor and resources to implement such measures. Moreover, in highly urbanized areas, wild populations are so sparse that the quantity of seeds collected from any single site is often insufficient for establishing isolated production beds. Both limited capacity and limited seed availability make strict spatial isolation infeasible.

Guo emphasizes that seed collection is only the beginning. Restoration in Yangtze River Delta region requires long-term trials to identify resilient species combinations and community dynamics. He envisions a future where seed banks, nurseries, land managers, and practitioners form an integrated system to support ecological restoration in Chinese cities.

Literature Cited

Basey, A. C., Fant, J. B., & Kramer, A. T. 2015. Producing native plant materials for restoration: 10 rules to collect and maintain genetic diversity. Native Plants Journal 16(1): 37–53

Robledo-Arnuncio JJ, Gil L. 2005. Patterns of pollen dispersal in a small population of Pinus sylvestris L. revealed by total-exclusion paternity analysis. Heredity 94(1): 13–22 

Van Rossum F, Stiers I, Van Geert A, Triest L, Hardy O. 2011. Fluorescent dye particles as pollen analogues for measuring pollen dispersal in an insect-pollinated forest herb. Oecologia 165(3): 663–674

The seed-based restoration pipeline for tallgrass prairie in the United States

Written by: Andrew Kaul   Reviewed by: Olga Kildisheva

Prairie loss and seed-based restoration

Tallgrass prairies have been removed from all but a few percent of their historic extent. To preserve this ecosystem, prairie restorations have been carried out for nearly a century. 

It is common to compare planted prairies (restorations/ reconstructions) to remnant prairies that have never been plowed, to evaluate the success of restoration efforts in terms of species composition and diversity, vegetation structure, and ecosystem functioning (Martin et al. 2005, Barak et al. 2017, Newbold et al. 2020, Kaul & Wilsey 2021, Kaul & Wilsey 2023). Restored prairies generally have lower diversity and floristic quality and have unique compositions compared to remnant areas that were never plowed. In practice, most restoration projects rely on commercially available seed mixes and the diversity and selection of species introduced in the initial seed mix is one of the most important predictors of plant diversity in restored prairies. 

The goal of research on the “seed-based restoration pipeline” is to identify those species that occur in remnants but are missing in restorations, and then to assess where these species are being lost in the pipeline. Many studies have directly compared remnant prairies to restored sites (long arrow on left), but more work is required to determine which species, or types of species (i.e. functional groups / traits) are selected for during each of the three transitions. The diagram above shows examples of studies that address these gaps in our understanding of restoration outcomes. Native species found in remnant sites may be lost if they are 1) not hand collected or sold by seed vendors 2) not included in seed mixes, or 3) if they do not establish when seeded.

Transition 1) What species are in the seed market, also known as the “restoration species pool”?

Two recent papers documented biases in the kinds of species that are sold by native plant vendors (Kaul et al. 2023a, Zinnen et al. 2025a). These studies show that there is bias towards species that are longer-lived (woody over herbaceous, perennial over annual), have larger ranges, bloom for a longer duration, and for forbs over graminoids. Both studies also outlined taxonomic/ phylogenetic signals in which species are selected from the species pool. According to these studies, multiple plant families were identified as under-represented in the commercial market, including Orchidaceae, Potamogetonaceae, Cyperaceae, Brassicaceae, Caryophyllaceae, and Euphorbiaceae.

Transition 2) What species tend to be included in restoration seed mixes?

Comparing seed mixes used in restorations to reference remnant sites, can be useful for documenting differences in species diversity, functional group ratios, and functional trait compositions (Kaul & Wilsey 2021, 2023). With the publication of large datasets on seed mixes (Zinnen et al. 2022b) and remnant prairies (Zinnen et al. 2025c) we are now able to broadly quantify these differences across the entire Eastern tallgrass prairie range. For instance, pollinator-oriented seed mixes are lacking the early-blooming forbs common in remnant prairies (Zinnen et al. 2025b).

I am currently working on a project which aims to 1) identify which kinds of species are common to remnants but are often missing from seed mixes, and 2) to quantify how seed mixes differ based on their name and description (Kaul, Zinnen, et al. In Prep). To achieve goal 1) we compared 578 commercial seed mixes from Midwestern seed vendors to species lists for 65 prairie remnants across eight Midwest states. We analyzed a subset of prairie remnants to test how the relative abundance of taxonomic and functional groups differ between remnants and seed mixes. To achieve goal 2) we codified each mix based on keywords in the name to compare mixes based on cost (high diversity vs. economy), soil type (ex. mesic vs. dry), height (ex. tallgrass vs. shortgrass) and intended value to specific animals (pollinators, birds, or wildlife). Preliminary analyses indicate that remnants and seed mixes have highly distinct compositions. We identified several “workhorse” species which are over-represented in seed mixes compared to remnants (ex. Desmanthus illinoensis) and “missing” species which are unique to remnants (ex. Dichanthelium spp., Comandra umbellata). In general, seed mix descriptions were associated with their composition, especially based on height and hydrology. However, mix compositions often overlapped significantly, suggesting that they consist of similar species despite their attributes. Adjusting future seed mix design to include important prairie taxa that are absent from restored sites may improve restoration outcomes by creating more remnant-like communities.

Transition 3) Which species establish and persist when planted?

Many, or even most of the species initially added from an establishment seed mix can be missing within the first few years of community assembly in a novel restoration site. Research on transition 3) investigates which species are “winners” and “losers” and seeks to identify the mechanisms that inhibit the successful establishment of each species (ex. Grman et al. 2015). In a recent study, I worked on a project applying this style of analysis to a seed-based restoration of an herbaceous understory in a temperate woodland (Kaul et al. 2023). We found that recruitment probability was linked to seeding rate, functional group, and conservatism – a measure of species’ fidelity to high-quality natural areas. Species sown at higher rates and with a low “ruderal” conservatism were more likely to have established after two years. This type of analysis is useful for directing future seed mix design, as some species can be sown at lower rates when they establish reliably on a per-live-seed basis. Other species may need to be increased in their relative abundance in the mix to reliably establish. Some groups are establishment-limited and do not recruit even when sown at high rates. Many mechanisms can prevent establishment including genetics, biotic factors, abiotic factors, and site conditions (De Vitis et al. 2022). Only careful research on species recruitment success and growth can inform best practices to increase the success of seed-based restoration efforts. 

References

Barak RS, Ma Z, Brudvig LA, Havens K (2022) Factors influencing seed mix design for prairie restoration. Restoration Ecology 30:e13581

Barak RS, Williams EW, Hipp AL, Bowles ML, Carr GM, Sherman R, Larkin DJ (2017) Restored tallgrass prairies have reduced phylogenetic diversity compared with remnants. Journal of Applied Ecology 54:1080–1090

De Vitis M, Havens K, Barak RS, Egerton-Warburton L, Ernst AR, Evans M, Fant JB, Foxx AJ, Hadley K, Jabcon J, O’Shaughnessey J, Ramakrishna S, Sollenberger D, Taddeo S, Urbina-Casanova R, Woolridge C, Xu L, Zeldin J, Kramer AT (2022) Why are some plant species missing from restorations? A diagnostic tool for temperate grassland ecosystems. Frontiers in Conservation Science 3

Grman E, Bassett T, Zirbel CR, Brudvig LA (2015) Dispersal and establishment filters influence the assembly of restored prairie plant communities. Restoration Ecology 23:892–899

Kaul A, Wilsey BJ (2023) Exotic species explain plant functional trait differences between seed mixes, restored and reference prairies. Applied Vegetation Science 26:e12709

Kaul AD, Barash M, Albrecht MA (2023a) Common, showy, and perennial species dominate a restoration species pool. Restoration Ecology 31:e13969

Kaul AD, Dell ND, Delfeld BM, Engelhardt MJ, Long QG, Reid JL, Saxton ML, Trager JC, Albrecht MA (2023b) High-diversity seed additions promote herb-layer recovery during restoration of degraded oak woodland. Ecological Solutions and Evidence 4:e12202

Kaul AD, Wilsey BJ (2021) Exotic species drive patterns of plant species diversity in 93 restored tallgrass prairies. Ecological Applications 31:e2252

Ladwig LM, Zirbel CR, Sorenson QM, Damschen EI (2020) A taxonomic, phylogenetic, and functional comparison of restoration seed mixes and historical plant communities in Midwestern oak savannas. Forest Ecology and Management 466:118122

Martin LM, Moloney KA, Wilsey BJ (2005) An Assessment of Grassland Restoration Success Using Species Diversity Components. Journal of Applied Ecology 42:327–336

Meissen JC, Glidden AJ, Sherrard ME, Elgersma KJ, Jackson LL (2020) Seed mix design and first year management influence multifunctionality and cost-effectiveness in prairie reconstruction. Restoration Ecology 28:807–816

Newbold C, Knapp BO, Pile LS (2020) Are we close enough? Comparing prairie reconstruction chronosequences to remnants following two site preparation methods in Missouri, U.S.A. Restoration Ecology 28:358–368

White A, Fant JB, Havens K, Skinner M, Kramer AT (2018) Restoring species diversity: assessing capacity in the U.S. native plant industry. Restoration Ecology 26:605–611

Zinnen J, Barak RS, Matthews JW (2025a) Influence of ecological characteristics and phylogeny on native plant species’ commercial availability. Ecological Applications 35:e3070

Zinnen J, Chase MH, Charles B, Harmon-Threatt A, Matthews JW (2025b) Pollinator seed mixes are phenologically dissimilar to prairie remnants. Restoration Ecology 33:e14352

Zinnen J, Chase MH, Charles B, Meissen J, Matthews JW (2025c) RELIX: A Dataset of Vascular Plant Species Presence for 353 Prairie Remnants in the Midwestern United States, with Prairie Remnant Metadata. Natural Areas Journal 45:150–158

Zinnen J, Matthews JW (2022a) Native species richness of commercial plant vendors in the Midwestern United States. Native Plants Journal 23:4–15

Zinnen J, Matthews JW (2022b) Species Composition and Ecological Characteristics of Native Seed Mixes in the Midwest (USA). Ecological Restoration 40:247–258

Expanding Our Reach: Introducing the INSR Ambassador Program and its Ambassadors

Written by: Marcello DeVitis, Sina Bohm, Andrew Kaul, Qiming Liang, Gabriele Vieira, Jill Wagner

Reviewed by: Olga Kildisheva

Since its establishment in 2015, one of the core objectives of the International Network for Seed-based Restoration (INSR) has been to connect professionals, practitioners, scientists, and stakeholders working on seed-based restoration. and facilitate the exchange of knowledge and experiences among them. By facilitating the exchange of knowledge and experiences, INSR aims to create a collaborative effort that will advance the field of seed-based restoration and ultimately have a positive impact on biodiversity conservation.

Since its inception, the network has grown and has been focused on ensuring the availability of key information to support native seed-based restoration worldwide. Some milestones include the production of the native seed film and the collaborative publications, such as the International Standards for Native Seed in Ecological Restoration, that became a reference in the field, and through organizing regular stakeholder engagement activities such as publishing a quarterly newsletter, organizing webinars, symposia, membership meetings, among others.

Even though the INSR had gained recognition globally, its Board was aware that the network wasn't reaching all regions and local communities and a more targeted, grassroots approach was necessary to engage with these underrepresented groups. To address this need, INSR recently established an Ambassador Program. INSR Ambassadors are members who assist the Board in connecting with local communities in their respective regions. They do this by promoting the organization at local events and conferences and by sharing useful resources. Ambassadors also help regional and local stakeholders connect with the broader community by sharing their stories through the INSR's channels. 

The INSR Ambassador Program launched in January 2025 and was fortunate to quickly attract interest from many members who wanted to become Ambassadors! We are excited to introduce our cohort of Ambassadors:

Marcello De Vitis

Marcello has been working on plant conservation and seed science with applications to restoration for more than a decade, conducting research and managing projects within Botanic Gardens, NGOs, and universities between Italy, the United Kingdom, and the Unites States, often working on projects with international breadth and impact. He served as a member of the INSR Board from 2017 to 2021 and he now serves as the Ambassador Program Lead. He is passionate about engaging communities, connecting people and leveraging efforts to advance knowledge and improve outcomes in plant conservation and habitat restoration. He currently works as a Conservation Officer at Botanic Gardens Conservation International supporting the implementation of The Global Biodiversity Standard, a site-based certification framework that recognises and promotes the protection, enhancement and restoration of biodiversity across multiple land uses and sectors. Marcello also sits on the Executive Committee of the recently formed Italian Network for Ecological Restoration.

Besides plants and conservation, he is passionate about hiking and playing volleyball.

Sina Bohm

Sina has been working in the fields of seed banking and plant translocations over the past 6 years in the Netherlands, trying to discover the limitations that populations of threatened plant species are currently experiencing. She feels lucky to collaborate with a dedicated team of researchers and practitioners who share the aim of safeguarding and restoring viable plant populations and ecosystem processes in the Netherlands. In a recent study she completed, she explored the role of microbial inoculation in plant translocation success. While conducting her PhD, she was the curator of the Dutch National Seed Bank (Foundation Het Levend Archief) and she is continuing to work in (seed-based) translocations and restoration within her new position as vegetation and landscape researcher at Wageningen University. Sina is keen to take part in the INSR Ambassador Program to further develop her skills and knowledge in the fields of plant translocations and ecological restoration and to engage in knowledge transfer internationally.

Andrew Kaul

Andrew is a restoration ecologist in the Center for Conservation and Sustainable Development at the Missouri Botanical Garden, in St. Louis, Missouri, USA. He studies plant community ecology, focusing on restoration of Midwestern US prairies, and woodlands. His research provides actionable recommendations to improve restoration practice, broadly following four crosscutting themes: seed-based restoration, land management, invasion ecology, and socio-ecology of restoration. His seed-based research addresses why certain species are present in restored habitats and others are not. Native species found in high-quality sites may be lost along three transitions in the “seed-based restoration pipeline” if they are 1) not hand collected or sold by seed vendors 2) not included in seed mixes, or 3) if they do not establish when seeded. His work has documented what kinds of species (based on functional groups or traits) tend to succeed or fail across each of these transitions. In addition to SER, he is also a member of the Ecological Society of America, and the Natural Areas Association. He also mentors a student each year through the American Society of Naturalists’ EEB mentor match program. In his free time, he enjoys baking, running, and playing with his three cats.

Qiming Liang

Qiming is a program officer at WWF China, focusing on grassland conservation in the Hulunbuir steppe—known as one of the best natural pasture on Earth. His involvement with INSR began by translating the documentary Native Seed: Supplying Restoration into Chinese. In collaboration with Bingqin Shan, one of SER & INSR’s China contacts, he contributed to translating key restoration standards and organized outreach events across China. Qiming also worked to promote a native seed supply chain in the Yangtze River Delta, emphasizing local plant materials and nursery networks. He is exploring the potential of using native seeds in WWF’s grassland restoration work, particularly for wetlands, waterbird habitats, and as high-quality forage for traditional natural pastures. Native seeds are closely linked to the traditional knowledge and cultural identity of Indigenous and local communities, as highlighted in the documentary. Qiming believes this connection is vital for place-based, community-led restoration, and he hopes to align his work with INSR’s vision of “the right seed, in the right place, at the right time.”

Gabriele Vieira

Gabriele is currently involved in academic and technical work related to seeds and seed-based ecological restoration in her region. She primarily works with species from the Atlantic Forest, which predominates in the Southeast region of Brazil, but she also works with Cerrado species—the Brazilian savanna-like biome—since she lives in an ecotone where both ecosystems meet. Her main focus is on forest seeds, especially seed quality, germination, and vigor, with an emphasis on their use in ecological restoration through direct seeding (known in Brazil as 'muvuca'). For her final undergraduate project, she is working on making the tetrazolium test more objective, aiming to improve its reliability in evaluating seed viability and vigor. Gabriele participates in discussions and initiatives related to native species restoration and contributes to Brazil’s Native Seed Committee. Outside academic activities, she enjoys reading literature from around the world, learning new languages, exploring data analysis, and practicing handicrafts with seeds. She sees her journey as a process of learning and contribution, and she is excited to keep deepening her knowledge and engagement in seed-based restoration.

Jill Wagner

Jill Wagner has been a forester in Hawaii for 30 years.  She started at the Amy Greenwell Ethnobotanical Garden as a horticulturalist for the garden, where she grew native Hawaiian species.  She received a Bachelors Degree from the University of Hawaii in Ethnobotany.  She has been conducting forest restoration projects for the State of Hawaii, Department of Hawaiian Homelands, The Nature Conservancy, The National Park Service, Kamehameha Schools and other private land owners.  She has trained people in ecosystem restoration and nursery management for decades.

She started the Hawaii Island Seed Bank (HISB) in 2008, which saves native seeds for large landowners on Hawaii Island. HISB supports farmers throughout the State by also banking food crop seeds for the Hawaii Seed Growers Network.  Crucially, it also serves as a model for small, regional seed banks, called Seed Arks. 

Ms. Wagner trains people all over the world so they can save their native and food crop seeds to build regional resiliency.  Seed Arks are off-grid, solar-powered seed banks that are built to keep seeds in the hands of the people.  Ms. Wagner is dedicated to supporting seed banks and networks everywhere.

Saving the Dutch Flora: Restoring Wild Plants in a Fragmented Landscape

Written by: Sina Bohm      Edited by: Olga Kildisheva

The Netherlands is a densely populated country. Anthropogenic impacts impose challenges for many wild species. Wild plant populations can experience many challenges: pollution, nitrogen deposition, genetic erosion, scarce pollinator presence, fragmented landscapes, and more. For many species, it is impossible to cope with these pressures by themselves. Often, human intervention is needed to ensure their local survival. 

As an ecologist, my work focuses on identifying the limitations that populations of threatened plant species face. The more I study these wild plant populations, the more I realize the complexity of the challenges they face and the interdependence of their relationships. Plants are connected to and rely on their surroundings in countless ways: bacteria and fungi shape soil function and make nutrients and water available; co-existing plant species affect each other's light conditions; animals forage on plants and disperse seeds; and pollinators promote gene flow. External pressures, often human-induced, can influence these intricate relationships and create cascading effects throughout entire ecosystems.

Ultimately, by identifying these challenges, I aim to find ways to improve the health and resilience of plant populations. In a fragmented landscape like the Netherlands, the natural recovery of many rare plants is difficult because of changes in land use. For example, traditional grazing practices with roaming sheep, which historically helped with seed dispersal, are now much less common.

For plant species that have lost their dispersal vectors, targeted reintroductions can help them colonize new, suitable habitats. The ultimate goal is to re-establish a healthy plant metapopulation with enough connectivity and restored dispersal methods to ensure its long-term self-sufficiency and resilience. Therefore, plant reintroductions can be an effective conservation tool, but only when they are part of a larger plan for ecosystem and process restoration.

I consider myself fortunate to collaborate with a dedicated team of researchers and practitioners who share the goal of protecting and restoring viable plant populations and ecosystems in the Netherlands. At the heart of this collaboration is the "The Living Archive Foundation” (Het Levend Archief). This organization manages the National Seed Bank of the native Dutch flora, which serves as both a safeguard for wild plants and a source of seeds for reintroductions. The foundation also facilitates communication among a diverse group of stakeholders from different institutions: nature managers who care for plant populations in the field, botanists and volunteers who collect seeds, and researchers like me who investigate the best practices for plant reintroductions.

In a recent study that I performed as part of my PhD research, I investigated the role of native microorganisms in reintroduction success of three rare plant species, Hypericum pulchrum, Solidago virgaurea, and Primula elatior. To do so, I grew plants from seeds from wild populations in a greenhouse – in total about 400 individual plants per species. Half of the plant containers were amended with a small amount of soil that I collected from the same wild populations, with the idea that the soil fungi and bacteria might affect seedling growth. The other half, I left untreated as a control. After growing the plants for a couple of weeks in the greenhouse, I transferred them to a suitable reintroduction site. I found that two species, Solidago virgaurea and Hypericum pulchrum, responded positively to microbial inoculation. However, for Primula elatior, microbial inoculation negatively affected plant survival and growth. 

Whether a species benefits from microbial inoculation likely depends on both its specific plant traits and the soil conditions. For example, Primula elatior grows under relatively nutrient-rich and moist conditions and can likely acquire most of the essential nutrients and water on its own, without the additional help of beneficial mycorrhizal fungi or bacteria. In contrast, Solidago virgaurea and Hypericum pulchrum, grow on poorer soils and appear to benefit from the presence of native microorganisms, which likely help with nutrient acquisition. The negative response of Primula elatior to microbial inoculation could have been pathogen-borne, as inoculation using soil from native plant population can transfer not only beneficial but also harmful microorganisms, though additional research is needed.

For conservation reintroductions, it would be very useful for practitioners to know which plant species are most likely to benefit from microbial inoculation and which are not. To answer this question, more experimental reintroductions are needed on a broad range of different plant species. My colleagues and I are working on this!

A Case of Active Urban Rewilding Shanghai Urban Biodiversity Education Base

Written by: Li Zhuang, Taoran Gua, Bingqin Shan

In 2019, Forest City Studio launched the Shanghai Urban Biodiversity Education Base to explore active urban rewilding strategies in high-density urban areas. Unlike passive rewilding approaches common abroad, China’s dense population, fragmented green spaces, and lack of native plant supply chains create obstacles to restoring ecosystem structure and function. This project aimed to restore urban biodiversity through guided design and management, offering a replicable model for urban wilderness construction.

The 1.7-hectare site, located in Pujiang Country Park, was formerly a flat, artificial forest. The design followed five key principles:

1)    Use native nursery stock from the Yangtze River Delta

2)    Design quasi-natural plant communities to foster ecological succession

3)    Diversify habitats to support wildlife movement

4)    Create features for target species conservation

5)    Minimize visual disturbance with low-impact infrastructure

A technical roadmap (Figure 1) guided the process from baseline surveys to habitat creation, species introduction, and long-term monitoring. The site was divided into 7 ecological zones, including Native Butterfly Attracting Zone, Native Shrub Zone, Native Aquatic Species Conservation Zone, Native Evergreen Tree Zone, Environmental Education Activity Zone, Mixed Native Evergreen/ Deciduous Tree Zone, and Native Deciduous Tree Zone to maximize habitat diversity within limited space.

Figure 1. Diagram of the technical roadmap

The site experienced a notable recovery of biodiversity in the first year. From May 2019 to November 2020, monitoring conducted with the project team and the East China Normal University recorded 260 native plant species, 255 insect species, 7 amphibian and reptile species, 71 bird species, and 6 mammals, showing higher biodiversity and animal population density than unrestored artificial forests nearby. Invasive species cover dropped from 65 percent to 5 percent in 1 year through competitive planting of pioneer species. In addition, maintenance has remained minimal by eliminating chemical control and relying on ecological processes such as natural pest regulation and nutrient cycling through deadwood decomposition.

Figure 2. Before restoration, the site was dominated by Alternanthera philoxeroides and Trifolium repens, with dead Ligustrum lucidum in the background.

Figure 3. Seven bee hotels filled with reed stalks were installed across different habitats, successfully attracting Megachilidae spp.and providing evidence of their nesting preferences.

Since its public opening in May 2020, the site has hosted 18 environmental education programs with 4,500 participants, including a nocturnal wildlife observation event that attracted over 1,500 visitors. Interpretive signage and citizen science activities further enhance its role as a living laboratory for biodiversity restoration and public engagement.

The project demonstrates the technical feasibility of active rewilding in large Chinese cities through habitat division, native species introduction, natural community construction, and ecological benefit assessment. It provides valuable insights for future applications in country parks, ecological corridors, and environmental education bases. However, limitations remain, particularly in balancing biodiversity goals with recreational use, which the team plans to address in future projects. Active urban rewilding still requires further research and policy support in China, but this case shows its ecological and social benefits are both achievable and scalable.

Yangtze River Delta Ecological Restoration Network (YRDERN）

Written by: Li Zhuang

Who We Are

The Yangtze River Delta Ecological Restoration Network (YRDERN) is a group of researchers, practitioners, and citizens dedicated to improving ecological restoration in one of China’s most populated and industrially developed areas, the Yangtze River Delta.

Established in 2024, YRDERN was founded in response to a growing realization. Ecological restoration efforts in the Yangtze River Delta have accelerated in recent years, yet the field remains fragmented and underdeveloped. Researchers, seed suppliers, landscape architects, policymakers, and practitioners often work in isolation, with limited coordination or shared standards. YRDERN was created to bridge these gaps by bringing together key stakeholders to foster a more integrated, locally informed approach to ecological restoration.

YRDERN Co-founder Bingqin Shan speaks at Shanghai Climate Week, sharing insights on native plant supply chains for ecological restoration.

Our Mission

Our vision is to help restore vibrant, resilient ecosystems across the Yangtze River Delta. We are committed to strengthening local knowledge, rebuilding native plant communities, and connecting people who care about the land. We believe that ecological restoration is not just a technical task, but a collective effort that requires shared learning, open dialogue, and cooperation.

Why We Start: Toward a More Connected Approach to Restoration

The Yangtze River Delta (YRD) is one of China's most economically developed regions, home to over 220 million people and a hub of urban growth and industrial development. But beneath this prosperity lies a fragmented and vulnerable ecological foundation.

Wetlands are degraded. Native plant communities have been replaced by simplified monocultures. Rivers are heavily engineered, and much of the urban greening lacks ecological function. While ecological restoration is now a national priority in China, practical progress in the YRD has been slow and uneven.

In this region, restoration faces multiple structural challenges:

●        Native plant supply chains remain poorly developed and fragmented

●        Scientific knowledge is rarely integrated into project planning and execution

●        Public engagement and long-term site stewardship are minimal

●        Technical standards and evaluation benchmarks are lacking

●        Stakeholders across disciplines and sectors have few opportunities to collaborate meaningfully

We are here to address this gap.

What We Do

YRDERN acts as both a knowledge hub and a collaboration platform, serving those working at the intersection of ecology, land management, design, horticulture, and community action.

Translating Knowledge into Local Practice

We translate key ecological restoration research from around the world into Chinese, making scientific concepts more accessible to practitioners. At the same time, we document lessons from local projects and co-develop practical guidance grounded in real-world conditions.

Topics include:

●        Native seed supply chain

●        Plant community dynamics and ecological succession

●        Species selection for functional and resilient landscapes

●        Soil and hydrology considerations in degraded habitats

●        Biotope-based site planning and evaluation frameworks

Sharing Insights and Building Dialogue

We regularly host knowledge exchange activities, both online and in person. Through these events, we bring together scientists, designers, nursery professionals, NGOs, and public-sector actors into discussion.

Topics include:

●        Technical challenges and solutions in restoration projects

●        Case studies, both successful and failed

●        Policy trends and implementation bottlenecks

●        New ideas from international practice and research

Supporting Community-Led Restoration Projects

YRDERN serves as a connector for those launching or supporting ecological restoration initiatives. Within our network, members collaborate on:

●        Project planning and design

●        Sourcing native plant material and conducting field trials

●        Monitoring site development and adapting practices over time

●        Mentoring younger professionals and supporting capacity building in the field

By fostering trust and coordination among diverse actors, we aim to create more consistent, ecologically grounded outcomes across the region.

Where We’re Headed

We believe the future of ecological restoration in the Yangtze River Delta depends on better relationships between theories and practices, between cities and nature, and among people who care about the land.

YRDERN is still young, but it is growing through collaboration, curiosity, and commitment to place. We welcome connections with peers around the world, whether you are a researcher, practitioner, educator, or policymaker. If you want to learn more or get in touch, please contact      Bingqin Shan (the_restor@163.com)

Understanding the Tetrazolium Test in Seed Analysis

Written by: Gabriele Vieira; Reviewed by: Olga Kildisheva

The tetrazolium test (TZT) has been developed and refined since the early 20th century, originally designed to assess seed viability. Over time, methodological advances have expanded its application to include the evaluation of seed vigor across various species, including forest species.

Seed viability and seed vigor

Seed viability refers to the ability of a seed to remain alive and capable of germination under ideal conditions. It indicates the presence of metabolically active and structurally intact embryonic tissues capable of developing into a normal seedling. Seed vigor, on the other hand, is a broader concept that encompasses the seed’s potential to germinate rapidly, uniformly, and produce strong seedlings even under suboptimal or stressful environmental conditions. While all vigorous seeds are viable, not all viable seeds are necessarily vigorous. Both attributes are essential for successful seedling establishment and can be evaluated through physiological and biochemical tests, such as the tetrazolium test.

Principles of the test

The TZT indirectly assesses the respiratory activity of the cells that make up seed tissues. It is based on the activity of dehydrogenase enzymes, which catalyze key reactions in mitochondrial respiration—particularly during glycolysis and the Krebs cycle. These enzymes reduce the colorless tetrazolium salt in metabolically active (living) tissues.

When immersed in the colorless tetrazolium solution, the dye penetrates seed tissues and interferes with the reduction processes of the living cells by accepting a hydrogen ion. In its reduced form, the tetrazolium solution becomes a red-colored, stable, non-diffusible substance called triphenyl formazan, or simply formazan.

Tetrazolium reduction reaction, Source: França-Neto, J. B.

Procedures of the test

Seeds are initially preconditioned using moist germination paper (slow moistening) to reach moisture levels that activate mitochondrial respiration. This method is preferred for larger seeds, as it allows tissues to imbibe water without damage and prevents death from anaerobic conditions like full water immersion. For smaller seeds, water immersion is a faster alternative but requires careful timing to avoid tissue damage.

Preconditioning may also include dormancy-breaking treatments. Seeds often need cutting, perforation, or seed coat removal to facilitate water and tetrazolium solution uptake. Sharp tools must be used to avoid damaging seeds and compromising test accuracy.

Tetrazolium solutions at 1% or 0.5% concentrations are common, with pH maintained between 6.5 and 7.5 to ensure proper staining. A 1% solution is prepared by dissolving 10 g of tetrazolium salt in 1 liter of distilled water.

During staining, seeds must be fully submerged and protected from light to prevent unwanted salt reduction. After staining in a light-proof container, seeds are incubated at species-specific temperatures and durations, following established protocols when available. Concentrations can vary if results remain reliable. Finally, seeds are rinsed to remove excess solution.

Tetrazolium test interpretation

The primary objective of the tetrazolium test (TZT) is to distinguish viable seeds from non-viable ones. This distinction is based on staining patterns and tissue integrity, allowing for a clear separation between the two groups. Moreover, it is critical that the technician has a thorough understanding of seed structures, which may vary depending on the species.

A. Embryo structure of tomato/bell pepper seed; B. embryo stained by the tetrazolium solution. (tg) tegument/seed coat; (ct) cotyledons; (en) endosperm; (rh) radicle-hypocotyl axis. Source: França-Neto, J. B.

In color interpretation, faint normal red typically indicates vigorous tissue, intense red signifies deteriorating tissue, and absence of staining denotes dead tissue. Viable seeds are those capable of producing normal seedlings in a germination test under favorable conditions, once dormancy has been overcome. These embryos typically exhibit uniform staining; however, partially stained embryos may also be considered viable if their staining patterns indicate metabolic activity. Necrotic tissues may be present in different regions of these embryos, and the viability classification depends on the size and position of such areas—not necessarily on the intensity of the staining. Tissue firmness is another crucial criterion that must accompany staining patterns to ensure proper identification and classification of viable seeds.

Non-viable seeds, by contrast, do not meet the above criteria. They often display irregular or poorly defined staining and contain flaccid or unstained essential structures. Seeds exhibiting abnormal embryo development—or other defective vital structures—are considered non-viable, regardless of their staining. Empty seeds must also be classified as non-viable. In the case of conifers, seeds with rudimentary embryos are likewise regarded as non-viable.

Another application of the TZT is to assist in categorizing the vigor levels of different seed lots and in estimating their performance under both optimal and stressful field conditions. Vigorous seeds are capable of developing into normal seedlings, whereas non-vigorous seeds are not. The TZT can also be used in conjunction with germination tests to account for potential dormancy-related discrepancies.

Tomato seeds stained by tetrazolium solution. A, viable and vigorous seed; B, viable non vigorous; C, non-viable seed; D, non-viable (dead) seed. Source: França-Neto, J. B.

In some forest seed laboratories in Brazil, such as the Laboratório de Sementes e Mudas (LASEM) at the Federal University of São Carlos, Sorocaba campus, standardized evaluation forms are used to support the assessment of seed viability and vigor. However, interpretation can still be subjective, as the accuracy of the test relies heavily on the technician’s skill and experience. Expanding the use of the test to a broader range of native species from the Brazilian flora would be extremely beneficial—especially in ecological restoration projects, where high seed diversity and time-sensitive decision-making are common. This highlights the importance of developing and publishing more species-specific TZT protocols, since morphological characteristics, dormancy-breaking requirements, and other factors play a critical role in achieving accurate evaluations.

In forest restoration projects, the tetrazolium test has proven to be a promising tool for evaluating the physiological quality of forest seeds due to its low operational cost and faster results when compared to germination tests. It enables a quick assessment of seed viability, especially for species that require long periods to complete germination, thus supporting timely decision-making by restoration teams—particularly in projects that employ the muvuca technique (see 'Muvuca' Direct Seeding Restoration Method for Biodiversity and People).

Given the test’s practical importance and interpretative challenges, technological solutions are increasingly relevant. With advances in computerized image analysis techniques, efforts should be directed toward developing software tools capable of digitally estimating seed viability and vigor, enhancing the accuracy and objectivity of TZT evaluations.

References

Association of Official Seed Analysts (AOSA). 2010. Seed vigor testing handbook. East Lansing, MI: AOSA.

Brasil. Ministério da Agricultura, Pecuária e Abastecimento. 2025. Teste de Tetrazólio. In Regras para análise de sementes (Chapter 5). Brasília, DF: Secretaria de Defesa Agropecuária. https://wikisda.agricultura.gov.br/pt-br/Laborat%C3%B3rios/Metodologia/Sementes/RAS_TZ 

França-Neto, J. B., Krzyzanowski, F. C., & Costa, N. P. 1998. O teste de tetrazólio em sementes de soja. Londrina: EMBRAPA-CNPSo. https://www.infoteca.cnptia.embrapa.br/infoteca/handle/doc/461306 

França-Neto, J. B. 1999. Testes de tetrazólio para determinação do vigor de sementes. In F. C. Krzyzanowski, R. D. Vieira, & J. B. França Neto, Vigor de sementes: conceitos e testes. Londrina ABRATES. https://loja.abrates.org.br/vigor-de-sementes 

França-Neto, J. B., & Krzyzanowski, F. C. 2018. Metodologia do teste de tetrazólio em sementes de soja. Londrina, PR: Embrapa Soja, Ministério da Agricultura, Pecuária e Abastecimento. (Documentos/Embrapa Soja, ISSN 2176-2937; n.º406). 
 https://www.infoteca.cnptia.embrapa.br/infoteca/bitstream/doc/1098452/1/Doc406OL.pdf 

International Seed Testing Association (ISTA). 2025. International rules for seed testing (Ed. 2025, Chapter 6: The tetrazolium test). Wallisellen, Switzerland: ISTA.

Fish as Seed Dispersers in the Amazon

Written by: Gabriele Vieira; Reviewed by: Olga Kildisheva

Seed dispersal plays a vital role in maintaining biodiversity and ensuring the ecological balance of forest ecosystems. While birds and monkeys are commonly associated with this process, in the seasonally flooded forests of the Amazon, an unexpected group also helps spread plant life: fish.

Many tropical tree species depend heavily on animals to transport their seeds. In fact, around 75% of them would struggle to survive in their natural state without these plant-animal interactions. In flooded tropical forests, numerous plants have adapted to the rhythms of rising and falling waters, timing their flowering and fruit production to coincide with the flood season.

Fish may have been the first vertebrate seed dispersers. During these seasonal floods, frugivorous fish venture into the forest in search of food, inadvertently aiding in seed dispersal. This process, known as ichthyochory, is especially important in such dynamic and complex landscapes. There, dispersal occurs not only through water currents (hydrochory) but also thanks to the crucial ecological role played by fish, which help maintain plant populations and promote the colonization of new areas.

Ichthyochory

Ichthyochory refers to the process of seed and fruit dispersal carried out by fish. This specific form of zoochory—in which animals act as dispersal agents—plays a crucial role in the regeneration and maintenance of aquatic ecosystems and seasonally flooded environments. One of the most iconic examples of such habitats is the igapó, a type of Amazonian floodplain forest that becomes submerged for several months each year due to the rise of blackwater rivers like the Rio Negro. In these nutrient-poor and waterlogged areas, many plant species have evolved to release their seeds during the flood season, taking advantage of water currents and aquatic fauna to spread their offspring.

Ecologically, ichthyochory supports the survival and diversity of many plant species that depend on water-based dispersal routes. Some fish swallow whole seeds or parts of fruits, and the seeds that pass through the digestive tract intact may be deposited far from their parent plant, where they can successfully germinate. This interaction is especially common among frugivorous fish, which are found in both freshwater and marine environments. Their feeding behavior not only nourishes them but also strengthens the connectivity between aquatic fauna and plant reproduction in flood-prone landscapes.

Key Species Involved

Researchers have identified at least 276 fish species as potential seed dispersers in tropical flooded forests. However, this estimate is based primarily on studies conducted in Neotropical floodplain areas, so the actual number may be even higher. In a study aimed at evaluating how different fish species contribute to seed dispersal in oligotrophic blackwater floodplain forests of the Amazon, a total of 41 fish species were found to contain seeds. Among them were Brycon amazonicus, Myloplus asterias, and Serrasalmus rhombeus (Weiss et al., 2023.).

Species of seed-dispersing fish found in the Uatumã River basin. Source: Weiss et al., 2023. 

Another study showed that seed size negatively influences the number of fish species that act as dispersers, with only a few capable of dispersing larger seeds. Among Brycon species, the probability of dispersal increases with individual body size. Large-bodied frugivorous fish also tend to masticate seeds less frequently than smaller species, which favors seed survival. Moreover, they can disperse a wider range of seed sizes—including non-floating and disperser-limited large seeds—playing a key role in the regeneration of flooded forests (Correa et al., 2015).

Brycon amazonicus measuring 35 cm. Source: Correa et al., 2015.

This feeding behavior, central to ichthyochory, varies according to fish and seed traits, and can lead to both dispersal and predation. During the seasonal floods in the Amazon, frugivorous fish enter the flooded forests to feed on fruits and seeds that are either floating on the water surface, submerged, or attached to vegetation. By consuming whole fruits or seeds, these fish inadvertently disperse seeds when they excrete them intact in new locations, often far from the parent plant. However, depending on the fish species and seed characteristics, some seeds may be crushed or digested, resulting in seed predation rather than dispersal. This dynamic feeding behavior highlights the dual role of fish as both seed dispersers and seed predators, making them key players in the regeneration and maintenance of flooded forest ecosystems.

Conservation Challenges for Frugivorous Fish

Despite the ecological importance of ichthyochory, the frugivorous fish responsible for this ecosystem service remain largely overlooked in conservation strategies. Several factors pose direct threats to these aquatic seed dispersers, particularly large-bodied species such as Colossoma macropomum, which play a key role in dispersing large, non-buoyant seeds. Overfishing has significantly reduced their populations, diminishing the effectiveness of seed dispersal across vast areas of flooded forests.

In addition to fishing pressure, the degradation of aquatic habitats represents an increasing threat. Deforestation along riverbanks and floodplain forests compromises the availability of fruits during the flood season, directly affecting the diet and feeding behavior of these fish. The construction of dams and other infrastructure also disrupts natural flooding regimes, fragmenting ecological corridors and limiting access to areas traditionally used for foraging and seed dispersal.

Although these impacts are still insufficiently quantified, they highlight the vulnerability of a mutualistic interaction that sustains much of the biodiversity in tropical flooded forests. Therefore, including frugivorous fish in conservation policies and sustainable fisheries management is essential to ensure the continuity of the natural regeneration cycle that connects aquatic and terrestrial ecosystems in the Amazon.

References

Correa, S. B., Araujo, J. K., Penha, J. M. F., Nunes da Cunha, C., Stevenson, P. R., & Anderson, J. T. (2015). Overfishing disrupts an ancient mutualism between frugivorous fishes and plants in Neotropical wetlands. Biological Conservation, 191, 159–167. https://doi.org/10.1016/j.biocon.2015.06.019 

Correa, S. B., Costa‐Pereira, R., Fleming, T., Goulding, M., & Anderson, J. T. (2015). Neotropical fish–fruit interactions: eco‐evolutionary dynamics and conservation. Biological Reviews, 90(4), 1263-1278. https://doi.org/10.1111/brv.12153 

Weiss, B., D. Santana, F., Petene Calvi, G., Costa, G., Zuanon, J., & Piedade, M. T. F. (2024). Effectiveness of fish assemblage as seed dispersers in Amazon oligotrophic flooded forests. Austral Ecology, 49(1), e13330. https://doi.org/10.1111/aec.13330 

Call for papers on "Impacts of Climate Change on Long Term Viability of Trees Species with Recalcitrant Seeds"

Narkis Morales San Martin, Adjunct Professor in the Departamento de Ecosistemas y Medio Ambiente at the Pontificia Universidad Católica de Chile, is co-editing a new article collection, “Impacts of Climate Change on Long Term Viability of Trees Species with Recalcitrant Seeds” on the journal Frontiers in Forests and Global Change. You can learn more about the scope of the topic and its accepted article types here: Impacts of Climate Change on Long Term Viability of Trees Species with Recalcitrant Seeds.

If you are interested in contributing to the special issue, please feel free to register via the link above. Frontiers will shortly provide further details.

Whilst not mandatory, you are encouraged to submit an abstract (or short outline of the manuscript) by 12 August 2022. The deadline for submissions is 12 October 2022, but Frontiers will aim to accommodate extensions on a case-by-case basis.

For further queries you can reach the dedicated specialist, Lily Campbell at orestsandglobalchange.submissions@frontiersin.org should you need any help.