The Salt River, known to the Akimel O’Odham people as On’k Akimel, has been dammed, diverted, mined, clear-cut, restored, and ignored over more than a century of intensive manipulation. Although the Hohokam and their descendants irrigated fields with its waters for centuries, diversion intensified dramatically in the early 1900s when the Salt River Project, backed by federal funding, constructed dams and levees that isolated the river from its floodplain and left much of the channel dry. What water remains flows through a handful of reaches where human infrastructure unintentionally or deliberately sustains year-round inundation. In the Sonoran Desert, where riparian and wetland areas cover only about 0.4 percent of Arizona’s land yet support up to 80 percent of its wildlife species, these wet oases are disproportionately important for regional biodiversity.

The research team selected three perennially wet sites representing fundamentally different management philosophies. The first, called Tonto, sits upstream of the urban sprawl within Tonto National Forest, where Stewart Mountain Dam regulates flow and recreationists, kayakers, anglers, and growing herds of feral horses exert ongoing pressure on the ecosystem. The second, Price, is what ecologists call an accidental wetland: it formed beneath and around the intersection of two major highways in the early 2000s and is sustained largely by storm-drain runoff from the roads, agricultural fields on the Salt River Pima-Maricopa Indian Community reservation, and occasional reclaimed wastewater discharge. Beyond access restrictions and occasional harvests of culturally significant plants by Indigenous Elders, Price receives essentially no management. The third site, Rio Salado, is a former dumping ground in downtown Phoenix that the City of Phoenix, the US Army Corps of Engineers, and Audubon Southwest transformed in a restoration project exceeding 110 million dollars, involving litter removal, invasive plant eradication, groundwater wells, and native plantings.

The monitoring itself was methodical and demanding. Bird surveys were conducted seasonally at fixed points along transects crossing the river channel, with a trained observer recording all birds seen or heard within a 50-meter radius over fifteen minutes during calm, clear mornings. Herpetofauna were documented through visual encounter surveys in nine plots per site, conducted by two observers once morning temperatures reached about 21 degrees Celsius, the peak of reptile activity. Vegetation was sampled intensively at the study’s outset in 2012 and again in 2022, with researchers assessing plant cover by species across thirty plots per site using standard Daubenmire cover classes. The team analyzed species richness, abundance, and evenness using the Shannon Diversity Index and analysis of variance frameworks, treating the sites as case studies rather than statistical replicates, a candid acknowledgment that landscape-scale ecology often demands messy but necessary long-term observation.

The results paint a portrait of divergence between taxonomic groups. Bird communities along the river proved remarkably stable, and at the restored Rio Salado site, average annual bird abundance actually rose by 56.7 percent, from 68.5 individual observations in 2014 to 107.3 in 2022, with gains across every habitat preference guild. Aggregated across all three sites, bird species richness showed a statistically significant increase over the study period. Herpetofauna told a different and more troubling story: reptile and amphibian abundance and diversity both declined significantly, with the trend more pronounced at the urban sites. The researchers caution that COVID-19 pandemic disruptions reduced sampling effort and statistical power, but parallel analyses of the same data using different methods have detected similar declines, and the known hazards of urbanization for reptiles, including roads, free-roaming cats, contaminated soils and water, and intensifying heat, lend biological plausibility to the pattern.

The plant communities underwent the most dramatic transformation of all. At both urban sites, vegetation became substantially more abundant, increasing by roughly 50 percent in total cover, and more species-rich by 2022, yet also less evenly distributed, with a few prolific cosmopolitan species such as giant reed, California bulrush, and broadleaf cattail dominating the landscape. The non-urban Tonto site, by contrast, grew more evenly diverse even as drought and horse grazing reduced its obligate wetland plants by about half and its tall trees by roughly two-thirds. This contrast between homogenizing urban sites and diversifying non-urban ones aligns with the well-documented global phenomenon of biotic homogenization, in which cities worldwide increasingly share the same suite of urban-adapted species.

Perhaps the study’s most provocative finding concerns the unmanaged accidental wetland at Price. Despite being wedged beneath a highway interchange and receiving no ecological stewardship whatsoever, Price harbored the two rarest plant species encountered in the entire survey: Ammannia coccinea, a wetland plant more typical of higher elevations, and Ludwigia erecta, a tropical species found nowhere else within 1000 kilometers. Native plants increased from roughly 23 percent cover to 31 percent, and plants culturally significant to the Akimel O’Odham and Piipaash peoples climbed from about 1 percent to 4 percent cover, even as invasive giant reed and tamarisk proliferated. These observations suggest that accidental wetlands, often dismissed as degraded wastelands, may quietly complement formal restoration efforts and deserve consideration as legitimate components of urban ecological infrastructure.

The findings also complicate the conventional wisdom surrounding invasive species management. At Rio Salado, managers invested heavily in eradicating species such as chaste tree, giant reed, globe chamomile, and floating water primrose, yet these plants recolonized from the surrounding urban matrix despite the costly efforts. Meanwhile, the authors found no evidence that introduced plants were suppressing native or culturally important species, which increased in abundance even at sites dominated by invaders. The team argues that management rationales should be critically evaluated before expensive eradication campaigns are launched, and that holistic goals such as increasing habitat complexity, supporting culturally significant plant populations, and protecting accidental wetlands may deliver greater conservation value than reactive removal programs.

The project’s most visible innovation may be its art. Working with City of Phoenix land managers, the researchers harvested the three most abundant marsh plants targeted for removal, which would otherwise have been sent to landfills, and pulped their biomass using field retting, caustic cooking, and a Hollander beater to create handmade paper. Each study site was represented by two sheets, one made from the dominant marsh species of 2012 and one from 2022, and the team hand-carved linoleum blocks to print community composition graphics directly onto the paper, with each icon representing one percent of annual plant cover. The resulting artworks were exhibited at the Nina Mason Pulliam Rio Salado Audubon Center, a university, and an art center between 2023 and 2025, reaching more than 2000 people and sparking public conversations about the river’s ecological past and future. For the researchers, this embodied mode of science communication demonstrates that ecological data, ecosystem stewardship, and community engagement can be woven together, and that the plants managers routinely discard may hold unexpected value as both scientific evidence and cultural material. As the United Nations Decade on Ecosystem Restoration unfolds, the Phoenix wetlands offer a compelling lesson: in social-ecological systems, surprises thrive where humans least expect them, and listening to a decade of data, sometimes printed on cattail paper, is the first step toward stewarding them wisely.

The study’s framing draws on a social-ecological perspective in which large-scale pressures, such as damming and urban expansion, interact with rapid pulses like drought, recreation, and management interventions to shape what lives in a given reach of river. The authors constructed a Press-Pulse diagram to situate their case studies within this broader context, treating community composition as a visible clue to underlying ecosystem processes that are otherwise difficult to observe directly.

The research also addresses a recognized gap in the urban wetland literature. A review cited by the team identified the mitigation of urban wetlands acting as ecological traps, where animals are attracted to habitats that ultimately reduce their survival, as one of the field’s largest unresolved questions. By monitoring birds, herpetofauna, and vegetation simultaneously rather than focusing on a single taxonomic group, the study captures some of the trophic complexity that single-group surveys miss, since vegetation structure creates habitat for animals while animals, including humans, disperse seeds that reshape the landscape. Invertebrates and fungi, however, were excluded from the analysis.

The authors emphasize that urban wetlands deliver a wide array of ecosystem services in arid settings where such features are spatially rare, including flood mitigation, water quality improvement, phytoremediation, carbon storage, heat reduction, denitrification, and habitat corridors, and even shelter for people experiencing houselessness. Infrastructure itself can generate habitat, as bridge overpasses create shaded niches for plants and animals seeking respite from the sun. Because long-term monitoring and citizen engagement are considered essential for managing these systems rather than working against them, the project’s blend of decade-scale surveys, collaboration with land managers, and public art exhibitions offers a model for how ecological research can remain connected to the communities it studies.

Subject of Research: Long-term changes in bird, herpetofauna, and plant community composition across managed, restored, and accidental urban wetlands of the Salt River in Phoenix, Arizona

Article Title: A portrait of changing community composition in three urban wetlands of the Salt River, Phoenix AZ USA

Article References: Ramsey-Wiegmann, L., Bateman, H. L., Childers, D. L., Green, H., & Makings, E. (2026). A portrait of changing community composition in three urban wetlands of the Salt River, Phoenix AZ USA. Discover Ecology, 2(1), Article 18. https://doi.org/10.1007/s44396-026-00030-3

Image Credits: AI Generated

DOI: 10.1007/s44396-026-00030-3

Keywords: urban ecology, wetlands, Salt River, Phoenix, biodiversity, herpetofauna, invasive species, restoration ecology, accidental wetlands, plant communities, long-term monitoring, science art

Urban farms have emerged as pockets of resilience within cities, providing fresh produce while fostering community engagement. Sager and Petrosino’s research aims to bridge the gap between academic knowledge and practical application by forming partnerships that leverage both theoretical frameworks and the realities faced by urban farmers. This approach not only enriches academic discourse but also empowers local communities to adopt sustainable practices that directly benefit their ecosystems and economies.

One of the study’s key findings is the recognition that urban farms can serve as laboratories for sustainability experiments. By studying and collaborating with these farms, researchers can identify effective strategies and techniques that promote sustainable urban agriculture. This iterative process of research and practice enhances our understanding of urban ecosystems, enabling us to develop more effective interventions that are tailored to specific local contexts.

At the heart of this research lies the concept of collaboration. Sager and Petrosino emphasize the importance of involving various stakeholders, including city planners, local governments, non-profits, and the farmers themselves. Engaging these groups in meaningful dialogue allows for a more holistic understanding of the challenges and opportunities present in urban farming. This collaborative approach fosters a sense of ownership among all participants, leading to more sustainable outcomes.

The researchers also explore the role of technology in urban agriculture and sustainability. Innovations such as vertical farming, hydroponics, and aquaponics present exciting opportunities for maximizing space and resources in crowded urban environments. However, the successful implementation of these technologies relies on a deep understanding of the local context, which can only be achieved through collaborative research efforts. The study points out that technology should not be viewed as a panacea; rather, it must be integrated thoughtfully within the framework of existing practices and community needs.

Another important dimension of this research is its focus on education and capacity building. Sager and Petrosino argue that empowering urban farmers with the knowledge and skills necessary to implement sustainable practices is crucial for long-term success. Through workshops, training sessions, and hands-on experiences, researchers can equip farmers with the tools they need to thrive in an ever-evolving landscape. This emphasis on education not only enhances individual farmers’ abilities but also strengthens community resilience as a whole.

As cities continue to expand and populations grow, food security becomes an increasingly pressing concern. Urban agriculture has the potential to alleviate some of this pressure by providing fresh, local produce to city dwellers. However, the researchers caution that scaling up these efforts in a sustainable and equitable manner requires intensive collaboration and careful planning. They highlight successful case studies that demonstrate how community-driven initiatives can lead to significant positive impacts on food systems and local economies.

Importantly, the study addresses the cultural aspects of urban farming. Urban farms can serve as spaces for cultural exchange, allowing diverse communities to come together and share knowledge, traditions, and practices. Sager and Petrosino emphasize that acknowledging and respecting cultural differences is essential for building effective partnerships. This not only enriches the collaborative process but also fosters a sense of belonging among participants, which is vital for the sustainability of these initiatives.

Furthermore, the research underscores the need for policy support to create an enabling environment for urban farms. Policymakers play a pivotal role in facilitating access to land, resources, and funding for urban agricultural projects. Sager and Petrosino advocate for policies that prioritize sustainability and community engagement, ensuring that urban farms are viewed as integral components of the urban fabric rather than fringe projects. These policy frameworks should also address equity, ensuring marginalized communities have access to the benefits of urban farming.

The environmental implications of urban agriculture are profound. By integrating green spaces into urban environments, these farms can contribute to biodiversity, reduce urban heat islands, and improve air and water quality. Sager and Petrosino’s research outlines specific strategies for optimizing these environmental benefits through collaborative practices that encourage ecosystem restoration and conservation. The researchers provide insights into how urban farms can act as ecological corridors, supporting wildlife and promoting ecological health.

As the authors highlight, the success of these partnerships hinges on fostering trust and mutual respect among all participants. Building lasting relationships is paramount for sustaining collaborative efforts, as it creates a network of support that extends beyond individual projects. By actively promoting communication and feedback mechanisms, stakeholders can continuously learn from one another, adapting practices and strategies as needed.

In conclusion, the research conducted by Sager and Petrosino presents a comprehensive framework for developing sustainable urban agriculture through collaborative partnerships. Their findings underscore the urgent need for stakeholders to work together, leveraging their unique expertise and resources to create resilient urban ecosystems. By focusing on education, technological integration, cultural understanding, policy support, and trust-building, communities can transform urban farming into a viable solution for contemporary challenges. This collaborative approach not only benefits local food systems but also paves the way for sustainable urban living that prioritizes both people and the planet.

With the future of our cities hanging in the balance, Sager and Petrosino’s work shines a light on the path forward. By bringing together researchers, urban farmers, policymakers, and community members, we can catalyze significant changes in urban food systems. This kind of multidisciplinary collaboration is essential to harness the potential of urban agriculture, ensuring that it can sustain future generations in an increasingly uncertain world.

Subject of Research: Sustainable urban agriculture and collaboration between stakeholders.

Article Title: From soil to sustainability: developing collaborative research practice partnerships with urban farms.

Article References:

Sager, M.T., Petrosino, A.J. From soil to sustainability: developing collaborative research practice partnerships with urban farms.
Discov Cities 2, 97 (2025). https://doi.org/10.1007/s44327-025-00141-8

Image Credits: AI Generated

DOI: https://doi.org/10.1007/s44327-025-00141-8

Keywords: Collaborative research, urban farming, sustainability, food security, community engagement, technology, education, policy support, environmental impact.

Microbial communities associated with trees—their microbiomes—play critical roles in supporting tree growth, nutrient cycling, and resilience against environmental stressors. These microorganisms include beneficial fungi such as ectomycorrhizal fungi, essential partners that colonize tree roots and enhance nutrient uptake, as well as bacteria that contribute to carbon and nitrogen cycling. However, the stresses imposed by urban environments—ranging from increased heat and air and soil pollution to fragmented habitats—are profoundly altering these microbial assemblages, often to the detriment of tree health.

The recent study, published in Nature Cities, focused specifically on the microbiomes of oak trees, a common ectomycorrhizal species, comparing urban street trees with those in rural forests. Through meticulous analysis of fungal and bacterial diversity, tree physical characteristics, and soil properties, lead researchers Jenny Bhatnagar and Kathryn Atherton uncovered a disturbing pattern: urban trees suffer from a pronounced loss of beneficial microbes alongside an increased presence of pathogens and microbes capable of generating potent greenhouse gases like nitrous oxide.

One of the most striking findings is the loss of ectomycorrhizal fungi in urban tree roots. These fungi are known to form symbiotic associations that not only aid in nutrient acquisition—particularly phosphorus and nitrogen—but also enhance water absorption and provide protection against diseases. Without these critical partners, urban trees are left vulnerable to a cascade of stressors, including drought and soil compaction. Concurrently, urban trees accumulate more pathogenic fungi and bacteria which can exacerbate wood rot and other diseases, undermining tree longevity.

Furthermore, the study highlights that urban tree microbiomes harbor more bacterial species capable of producing nitrous oxide (N2O), a greenhouse gas with a global warming potential approximately 300 times greater than carbon dioxide. Conversely, methanogens, bacteria that consume methane and thus mitigate greenhouse gas emissions, are less abundant beneath urban trees compared to their rural counterparts. This shift suggests that urban tree-associated microbial communities could inadvertently contribute to urban greenhouse gas emissions, compounding climate concerns.

The disruption to tree microbiomes is closely tied to specific urban environmental conditions—higher temperatures caused by urban heat islands, reduced soil moisture, degraded soil organic matter, and increased deposition of atmospheric aerosols and pollutants. These factors directly and negatively influence microbial diversity and function, creating a hostile environment for many of the beneficial organisms crucial for tree health.

Although the study centers on oak trees, which depend on ectomycorrhizal fungi, the researchers suggest that similar disruptions may affect other tree species and plants that rely on different types of symbiotic fungi or microbial communities. However, this remains an open question and a ripe area for future investigation, emphasizing the need to broaden the scope of urban microbiome research across diverse urban flora.

Understanding these microbial relationships is more urgent than ever given the rapid pace of urban growth worldwide. It is estimated that urban areas will double in size by 2050, with profound implications for natural habitats and the resilience of urban ecosystems. In the United States alone, over 20% of forest land is projected to be overtaken by urban expansion by mid-century, with 90% of the population living in cities. The health of urban tree populations will directly impact air quality, carbon sequestration, urban cooling, and biodiversity conservation.

Another compelling aspect of this research is its application potential. By identifying the key environmental drivers behind microbiome disruption, such as soil organic matter decline and moisture stress, urban planners and environmental managers can implement targeted strategies to restore and maintain microbial diversity. Simple interventions like adding mulch around trees to improve soil moisture and organic content could foster the recovery of beneficial microbial symbionts, enhancing tree stress tolerance and longevity.

Importantly, the research team is pioneering “microbiome rewilding” experiments aimed at reintroducing beneficial mycorrhizal fungi into urban soils. This approach draws inspiration from forest restoration ecology, where inoculating tree roots with mutualistic fungi has successfully reduced mortality rates. Rewilding urban tree microbiomes has the potential to transform city landscapes into thriving ecosystems, improving tree survival rates and the ecological services they provide.

From a broader perspective, integrating microbiome knowledge into urban forestry policy could revolutionize how cities manage their green spaces. Microbial considerations could enhance urban tree resilience, improving ecosystem services such as air pollution filtration, carbon capture, and microclimate regulation, while also contributing to more equitable access to healthy green spaces across socio-economic boundaries.

In addition to informing urban management, these findings have implications for public engagement. Understanding that the tiny organisms beneath a tree’s surface can drastically affect its health and the broader urban environment encourages a shift in how individuals and communities care for urban trees. Simple actions like applying mulch and advocating for green infrastructure can support these complex microbial networks and contribute to healthier urban forests.

The study reminds us that urban trees are not solitary organisms but are embedded in intricate and dynamic relationships with countless microbial partners. As urban pressures escalate, safeguarding these invisible communities is critical to preserving urban forest health, mitigating climate impacts, and enhancing the quality of urban life. The research from Boston University opens new horizons, signaling a paradigm shift toward viewing urban vegetation through the lens of microbial ecology, with profound consequences for sustainable urbanization worldwide.

The path forward involves rigorous exploration of the specific microbial and environmental factors that most strongly predict urban tree health outcomes. Advanced modeling efforts are underway to delineate these relationships, hopefully enabling the identification of priority targets for urban afforestation and management practices. Coordinated interdisciplinary efforts that unite microbiologists, ecologists, urban planners, and policymakers will be vital in translating these findings into actionable solutions.

This research also underscores the broader implications of urban environmental change on interconnected ecosystems, human health, and climate dynamics. As cities aspire toward net-zero emissions and climate resilience, the microbiological underpinnings of urban forests must be elevated to a central role in scientific inquiry and practical interventions.

By shedding light on the complex microbial dimensions of urban tree health and offering promising avenues for remediation, this study serves as a call to action for researchers, city officials, and residents alike. The future of urban trees—and by extension, urban life—depends on recognizing and nurturing the invisible microbial allies beneath our feet.

Subject of Research:
Not applicable

Article Title:
Disruption of the oak tree microbiome with urbanization

News Publication Date:
3-Oct-2025

Web References:
http://dx.doi.org/10.1038/s44284-025-00322-x

References:
Bhatnagar, J., Atherton, K., et al. (2025). Disruption of the oak tree microbiome with urbanization. Nature Cities. DOI: 10.1038/s44284-025-00322-x

Keywords:
Microbiota, Mycorrhizal fungi, Fungi, Forest ecosystems