Bunkered ex situ plant conservation and páramo biodiversity farms

By Iván Jiménez (Center for Conservation and Sustainable Development, Missouri Botanical Garden), Carlos A. Vargas (Herbario, Jardín Botánico de Bogotá José Celestino Mutis), Carlos I. Suárez (Colecciones Vivas, Jardín Botánico de Bogotá José Celestino Mutis), and Erika Benavides (Finca Milmesetas, Pasca, Sumapaz, Cundinamarca, Colombia)

As anthropogenic pressures on biodiversity mount, plant species conservation increasingly requires the integration of a variety approaches, including ex situ conservation: the maintenance of populations in intensively managed living collections. Conventional seed banking is commonly regarded as a particularly effective and efficient method of ex situ conservation, because a large number of seeds representing many species can be stored for long periods in relatively small spaces at seemingly low cost. It entails drying seeds to 15% relative humidity and storing them at −20 °C. For some “exceptional” species that cannot be easily represented in conventional seed banks, cryopreservation and associated methods are seen as good choices. In contrast, living collections of whole growing plants are often seen as relatively inefficient, requiring more space and care.

A particular problem with seed banks and cryopreservation projects, however, is that they may suffer from a “bunkered” conception of biodiversity conservation. By example, the Millenium Seed Bank is a “flood, bomb and radiation proof” underground facility designed as a “global insurance policy” to conserve seed diversity. Although focused on crops rather than wild plants, the Svalbard Global Seed Vault has a similar bunker ethos, aiming to guard against the loss of plant diversity due “not only to natural catastrophes and war, but also to avoidable disasters, such as lack of funding or poor management”. These bunker-like seed banks invite obvious questions: what protects them from lack of funding, miscalculation, poor management or extreme political ideology?

Both bunker-like seed banks are remarkable spatial concentrations of resources for ex situ conservation, seemingly at odds with the key biological insight according to which a large spatial spread decreases the probability of extinction. At the same time, these seed banks correspond to what Bruno Latour called “centers of calculation”, institutions where observations and specimens from faraway locations are amassed, organized and combined to produce scientific knowledge. Centers of calculation were foundational to the expansion of European colonialism. The Millenium Seed Bank and the Svalbard Global Seed Vault may be seen as contemporary extensions of the same colonial mindset, repurposed in the context of biodiversity conservation.

While other seed banks might not seem as obviously colonial, many do dislocate plant propagules from their original wild plant populations and human milieu. Most plant diversity in ex situ collections is held in the Global North, largely away from sources at the main centers of plant diversity. Even seed banks focused on nearby regional floras remove propagules from their immediate human and non-human environments.

And while not all seed banks boast about their bunker-like properties, many do sit well within the “ark paradigm”, whereby representative samples of species must be secured away (perhaps even in the back side of the moon, as suggested by a foundational paper) in preparation for a likely apocalyptic future of widespread extinction. The ark paradigm is clearly articulated in a chapter about the role of botanical gardens in ex situ plant conservation: “The primary goal of ex situ collections is to maintain a representation of the species as a source of material for restoration, should the species be lost in the wild, and this should be done as effectively and efficiently as possible”. This salvific post-extinction role for seed banks (let alone cryopreservation projects) seems to have little support in practice.

An alternative to the ark paradigm suggests that ex situ conservation can play a primary role before the extinction of wild populations. Ex situ collections may be used for research, training, education, awareness-raising and incentive programs that directly target the causes of primary threats to wild populations. In terms of this pre-extinction role, the conservation value of ex situ collections may be determined by their geographic location. The primary threats to many plant species are local. To address the causes of such threats, the most valuable living collections may be those able to engage the human communities coexisting with threatened plants. Bunkered living collections, removed from the human and non-human environment of the source plant populations, would likely be ineffective and inefficient at this task.

The alternative to the ark paradigm also suggests that ex situ conservation can play a central role in offsetting the effects of threats to wild populations, through the restoration of wild populations via reinforcement. Ex situ collections may provide plant stock for population management aimed at mitigating the effects of threats. Here, again, the geographic location of ex situ collections may determine their effectiveness and efficiency. Ex situ collections in the vicinity of threatened species would seem best for reinforcement programs. Moreover, issues related to propagation of whole growing plants would seem far more germane in this context than the worries about long-term storage prioritized by the ark paradigm and pursued in seed banks and cryopreservation projects.

An initiative adopting this alternative view of ex situ conservation is taking place in the páramo de Sumapaz, perched on the Eastern Colombian Andes. Páramos are high elevation ecosystems that are central for provisioning water to human populations in the tropical Andes. They are perilously affected by global change. The páramo de Sumapaz occupies about 315,000 hectares and, based on analysis of a recently compiled and edited database, hosts more than 3,000 plant species. Although the conservation status of 76% of these species has yet to be evaluated, currently 64 species are known to be threatened.

In this context, a group of researchers including local campesinos as well as staff and students from the Jardín Botánico de Bogotá, Parque Nacional Natural Sumapaz, Universidad Nacional de Colombia, Washington University in St. Louis, and the Missouri Botanical Garden, are engaged in participatory action research, with partial support from the Living Earth Collaborative. The aim is to develop the concept of “páramo biodiversity farms”, provisionally defined as properties in or near the páramo that derive economic benefits from at least one of four activities: i) biodiversity research, ii) education about biodiversity, iii) ex situ conservation of threatened plant species in living collections, and iv) plant stock production for population or ecosystem restoration.

A pilot páramo biodiversity farm began in 2019 at “El Carmen”, a 40-hectare property in the Sumapaz region. This pilot is focused on an ex situ collection of plants in the genus Espeletia (Asteraceae). Although páramo biodiversity farms would include work on many other plants, the focus on Espeletia at El Carmen is strategic. First, Espeletia are dominant “nurse-plants” in páramos and largely determine the physical structure of these ecosystems. Second, despite being locally dominant, several taxonomic species of Espeletia are threatened. Third, obtaining meaningful monitoring data for conservation is often difficult because the species boundaries in Espeletia are poorly understood and field identification is problematic.

Espeletia plants are dominant in páramos, as shown in the picture of the páramo de Sumapaz on the left. Orlando Romero, a campesino working for the Parque Nacional Natural Sumapaz, collects Espeletia seeds for the living collection at El Carmen. Photos by Iván Jiménez.

The living collection at El Carmen serves multiple purposes. First, it is a “common garden” experiment, designed to understand species boundaries and phenotypic characteristics of Espeletia species from Sumapaz. The experiment entails propagating plants from seeds sourced from +500 mother plants occurring across the páramo de Sumapaz, initially in a nursery and subsequently in an outdoor landscape. Second, the living collection serves as a facility to train local students in plant biology and conservation. Third, the collection conserves ex situ threatened Espeletia species that are endemic to the Sumapaz region. Finally, the living collection may serve as a seed-increase field providing Espeletia plant stock for future population or ecological restoration projects.

The picture on the left shows part of the living collection at El Carmen, including seedling trays (forefront), germination containers (right and back), and 3-year old plants in pots on the ground (back left). On the right Rudy Ortiz (left) and Natalia Beltrán, both biology students at the Universidad Nacional de Colombia, measure Espeletia seedlings at El Carmen. Photos by Erika Benavides.

A central theme of the project is the participation of local campesinos as co-investigators and managers, alongside researchers and officials from academic and environmental institutions. Achieving true participatory research and exchange of knowledge across these actors is far from trivial. Nonetheless, a concrete result of the project is that co-investigators, including campesinos, developed a sophisticated understanding of the phenotypic groups of Espeletia and their geographic distributions across Sumapaz, facilitating conservation monitoring programs. This increase in plant awareness among people coexisting with Espeletia plants is a key step towards addressing the causes of threats to páramo plant diversity. Campesino management of the ex situ collection at El Carmen (and the associated information) provides modest but direct economic benefits to a local family. We hope it also builds local capacity for the governance of biodiversity and collaborative relationships between campesinos and institutions focused on studying and managing biodiversity.

Jorge Penagos (left) and Erika Benavides, both campesinos from Sumapaz, record survival of Espeletia seedlings in the living collection at El Carmen. Photo by Rudy Ortiz.

The pilot biodiversity farm at El Carmen hints at how ex situ collections of whole growing plants may help prevent extinction of wild populations. This kind of collection is often thought to be inefficient because requirements of space and resources may be higher than for seed banks and cryopreservation. Collections of whole growing plants for ex situ conservation can indeed be costly when bunkered inside botanical gardens. But they can be more efficient when spread across lands owned by human communities coexisting with threatened plants. We suspect that páramo biodiversity farms may not be more costly than comparable seed banks in the Global North. And the benefits from páramo biodiversity farms would include ex situ collections that act not only as safeguards (the ark paradigm) but also as tools to prevent extinction in the wild and promote local (rather than colonial) biodiversity governance. Studies comparing costs and benefits, beyond back-of-the-envelope calculations, are needed to determine which approaches to ex situ conservation are more effective and efficient in different regions of the world.

How does prescribed fire affect a threatened terrestrial orchid?

By Leighton Reid and Ryan Klopf

Leighton Reid is an assistant professor of ecological restoration in the School of Plant and Environmental Sciences at Virginia Tech. Ryan Klopf is the Mountain Region supervisor and natural areas science coordinator for the Virginia Natural Heritage Program. They describe a new research project that aims to understand how an important restoration tool impacts the population dynamics of federally threatened small whorled pogonia orchids. This project has an open PhD position available to start in January 2023; details can be found at the end of this post.

Deep in the heart of Virginia’s Shenandoah Valley, nestled against the western edge of the Blue Ridge Mountains, two clusters of small, green orchids grow in the dappled sunlight of a woodland understory. The orchids are small whorled pogonias (Isotria medeoloides) – a rare species that is considered threatened by the United States government because its population is declining so quickly that it could become endangered in the foreseeable future. We have monitored these populations for the past two summers, keeping tabs on every individual, to learn how this species is affected by one of the most important restoration tools in North America – prescribed fire.

A small whorled pogonia orchid with two flowers at Mount Joy Pond Natural Area Preserve. Photo: Lindsay Caplan.

Small whorled pogonia

As their name implies, small whorled pogonias are small (≤25 cm) and whorled (their leaves radiate outward from the stem). This species is a member of the Pogonieae, an orchid tribe that includes species in Asia and eastern North America. Its closest relative is the large whorled pogonia (I. verticillata) which sometimes grows alongside small whorled pogonia, but is distinguished by its purplish stem (small whorled pogonia has a whitish green, glaucous stem).

Small whorled pogonia (left) with a whitish, glaucous stem compared to large whorled pogonia (right) with a purplish stem base. Photos: Sara Klopf (left) & JL Reid (right).

Small whorled pogonias emerge from the leaf litter in late spring and in some years produce one or two solitary greenish yellow flowers, particularly when plants are exposed to more sunlight. Their flowers do not require any help with pollination; they produce the same amount of seed whether they are cross-pollinated or pollinate themselves.

The seeds themselves are tiny – like vanilla seeds, which are in the same orchid sub-family (Vanilloideae). The parent plant (which is usually both a mother and a father) provides almost no resources at all to its offspring. Each seed’s fate is closely linked to whether or not it finds a mycorrhizal fungus in the Russulaceae family to help it acquire the resources that it needs to survive and grow. In a typical relationship between plants and mycorrhizal fungus, the fungus scours the soil for nutrients like nitrogen and phosphorus and provides them to the plant in return for energy in the form of carbohydrates, which the plant produces through photosynthesis.

A developing fruit on a small whorled pogonia orchid at Mount Joy Pond Natural Area Preserve in June 2022. Photo: Andres Cunningham.

Fire and water at Mount Joy Pond

The story of this research project begins about 80 years ago, in a DuPont chemical plant in Waynesboro, Virginia. In the 1930s-1950s, the DuPont facility used mercury to produce rayon – a synthetic, silk-like fiber. Some of the mercury escaped from the plant and leaked into the South River – a tributary of the Shenandoah River. Mercury is a neurotoxin, and in the environment it can accumulate to dangerous levels in animals that are higher on the food chain, like fish. For many years, people living along the South River have been warned about the poor water quality and advised not to eat the fish.

In 2016, DuPont reached a $50 million USD settlement with the United States Department of Justice, the Department of the Interior, and the Commonwealth of Virginia to restore habitat for wildlife in the South River watershed, enhance water quality, and improve recreational areas. This settlement represented one of the largest environmental damage settlements in United States history.

Some of the DuPont settlement money was allocated to the Virginia Natural Heritage Program, a division of the Virginia Department of Conservation and Recreation that uses science-based conservation to protect Virginia’s plants and animals. Specifically, funds were provided to allow the Virginia Natural Heritage Program to protect and restore woodland habitat surrounding a unique wetland at the Mount Joy Pond Natural Area Preserve in Augusta County.

Briefly, Mount Joy Pond is a Shenandoah Valley Sinkhole community; that is, it is a groundwater-controlled wetland that floods intermittently when water percolates up through underlying carbonate rocks and then floods over the top of a clay lens perched in a layer of soil derived from the overlying sedimentary rocks. When this happens, the water becomes trapped, like water in a saucer. This unique situation creates wetland habitats which have persisted for the past 15,000 years and contain numerous rare and disjunct species, including the globally rare Virginia sneezeweed (Helenium virginicum). There are several dozen Shenandoah Sinkhole ponds, but only a handful of them are protected.

Virginia sneezeweed, an endemic species in the southeastern United States with disjunct populations in Virginia’s Shenandoah Valley sinkhole ponds and in a similar wetland situation in the Ozark Mountains of southern Missouri. Photo: JL Reid.

In the past, Mount Joy Pond filled with water every few years, but in recent decades it has filled up less and less often. To restore the wetland’s hydrology, the Virginia Natural Heritage Program set out to thin the surrounding forest and re-introduce fire to prevent fire intolerant trees, such as red maple, from regenerating. This may sound counterintuitive to some, but the logic is this:

• Each tree is like a drinking straw sucking water out of the ground and releasing it into the air via transpiration. If there are a lot of trees, the groundwater may stay too low to fill up the pond.
• Fire used to be much more common in the Shenandoah Valley. Prior to European colonization, Indigenous People burned the landscape and maintained much of it as savanna and open woodland – ecosystem types that have fewer trees than present day forests.
• By removing some trees and reintroducing a regular fire cycle, land managers at Mount Joy Pond Natural Area Preserve can restore an open woodland and raise the groundwater level, causing the pond to flood more often.

The Virginia Natural Heritage Program began to implement this restoration project in 2017, and the first thinning operations and burn were a success. In the years since, the groundwater level appears to have gone up, suggesting that the hydrological restoration plan is working.

Small whorled pogonia discovery

In the first spring after that first fire, a botanist was surveying the burned woods near the pond and found something unexpected – a small population of small whorled pogonia orchids, which had not been seen previously in the preserve despite extensive surveying by the Virginia Natural Heritage Program’s inventory team. Were the orchids there all along and nobody noticed them? Maybe. Or maybe the fire helped the orchid population emerge after years of suppression in the dense leaf litter in the shady understory.

Our team uses a grid sweep survey to search for new small whorled pogonia individuals in June 2022. Photo: JL Reid.

The story became more complicated later that summer when a more intensive search turned up a second population of small whorled pogonia orchids on the preserve – this one in an area that had not been burned.

The immediate consequence of discovering the new pogonia populations was that the United States Fish and Wildlife Service expressed concerns that future fire management might be detrimental to this threatened species. Nobody had studied how small whorled pogonia responds to fire, and there was a chance that burning could damage the population, even if it was good for the nearby pond’s hydrology. Of course, there was also a chance that not burning could damage the population. With fire, inaction is still an action.

To help settle the issue, the United States Fish and Wildlife Service agreed to sponsor a PhD student to study the small whorled pogonias at Mount Joy Pond and figure out how their population dynamics are impacted by prescribed fire.

Lindsay Caplan and Jimmy Francis monitor a population of small whorled pogonias at Mount Joy Pond Natural Area Preserve in June 2022. Photo: JL Reid.

Effects of prescribed fire on small whorled pogonia orchids

The main goal of our ongoing research is to understand how prescribed fire impacts small whorled pogonias. To do this, we will map and monitor the two subpopulations and the woodland plant communities in which they live. Over the next two years, one of the two subpopulations will be burned during a winter or early spring prescribed fire, and we will continue monitoring to document changes in plant vigor, reproduction, and population size. We will pay special attention to the light environment, which seems to be important for small whorled pogonia reproduction, and to the diversity and composition of soil fungi, which are important for small whorled pogonia emergence. We will also conduct annual surveys of the entire reserve to search for additional populations.

Ethan Dunn uses a canopy imager to measure canopy cover, photosynthetically active radiation, and leaf area index over a tiny small whorled pogonia individual in July 2021. Photo: JL Reid.

This project is just beginning. To date, we have monitored the two populations for two growing seasons (2021, 2022). There is still much work to be done. One of the next steps will be to produce an accurate map of each plant’s location, which will require centimeter-level precision using high-quality GPS equipment under a forest canopy.

We are currently seeking a PhD student to lead this research project starting in January 2023. A description of this opportunity is below. This project is an excellent opportunity for a student to develop expertise in ecological restoration and threatened species conservation from both a scientific perspective and an on-the-ground land management perspective.

Ultimately, the results of from this study will inform management of natural areas and small whorled pogonia restoration projects throughout the species’ wide range – from Ontario to Georgia.

A new perspective for plant translocation science: the International Plant Translocation Conference has been born

By Thomas Abeli, Department of Science, Roma Tre University

Many plant species around the globe are threatened with extinction or have already been extirpated from the wild as a result of habitat loss, pollution, alien invasive species, and climate change. Among the possibilities in the toolkit of conservation biologists to halt and reverse the loss of plant diversity, translocation is now a commonly used approach. Translocation is defined by the International Union for the Conservation of Nature (IUCN) as a deliberate transfer of species from one site to another for conservation purposes that includes different types of movements: population reinforcement of small and genetically depauperate populations, reintroduction of species within their native range in sites where they occurred in the past and from where have been extirpated, and conservation introduction of species outside their indigenous range. While the primary motivation for translocation is often the recovery of single species, translocation also plays a key role in ecosystem restoration – enabling the United Nations to achieve global goals for its 2020-2030 Decade of Ecosystem Restoration.

Reintroduction of Pyne’s ground-plum (Astragalus bibullatus) was featured in a talk by Dr. Matthew Albrecht on adaptive management in reintroduction programs at the first International Plant Translocation Conference in June.

Plant translocation is sometimes highly successful, sometimes dramatically discouraging and unsuccessful. Such variability in translocation outcome is rooted in the still poor understanding and standardization of techniques given that the field of translocation science remains in an early stage of scientific development. Translocation programs are challenging and complex, often requiring an interdisciplinary team that may include conservation biologists, restoration ecologists, taxonomists, geneticists, practitioners, policy makers, indigenous peoples, citizen scientists, and local community members.

It is common in science to organize periodical conferences where scientists from around the world meet and discuss recent findings and share ideas in a specific field. Although plant translocation is often discussed in national and international conservation biology conferences, we lacked a dedicated conference or forum to share experiences and improve plant translocation science and practice to deliver more effective conservation outcomes. With the aim of filling this gap, a group of field-leading scientists developed the 1^st International Plant Translocation Conference as a new forum to share ideas and advance the field of plant translocation.  After multiple delays over the past two years due to the COVID-19 pandemic, the Science Department of the Roma Tre University hosted the inaugural International Plant Translocation Conference (IPTC2022) from 20 to 23 June 2022 in Rome, Italy. Designed as a hybrid conference platform to promote global participation and inclusion, the conference included 71 participants (including online attendees) representing 19 countries and 5 continents.

Attendees and staff of the 1^st International Plant Translocation Conference (IPTC2022) in Rome.

With nine international keynote speakers from the International Union for Conservation of Nature (IUCN), the Center for Plant Conservation (United States), the Missouri Botanical Garden, the Curtin University (Australia), the Meise Botanical Garden (Belgium), the Liverpool John Moores University (United Kingdom), the University of Cagliari, the University of Pavia and the Botanical Garden of Rome (La Sapienza University), along with nearly 40 talks, a poster session, workshop, social events, and a field trip, the IPTC represented an outstanding opportunity for the global community of conservation biologists involved in plant translocation to present recent findings, best practices, learn from each other’s experiences, initiate new collaborations, and transfer knowledge to the next generation of conservation scientists and practitioners. The congress was organized around five thematic sessions covering topics related to translocation techniques, ex situ conservation approaches to support translocation, data sharing and ethics, and translocation case studies from the Mediterranean bioclimatic region.

Additionally, the congress discussed the controversial topics of assisted migration and de-extinction, which generate international news headlines. Assisted migrations are debated on one side for the opportunity they represent to save species threatened by climate change and, on the other side, for the risks they imply for recipient ecosystems. De-extinctions represent the last frontier of conservation. While still in the hypothetical stage, the idea of ​​reviving extinct species is fueling a wide scientific debate among supporters, opponents, and those who advocate conservation approaches that are more pragmatic. Research presented at the IPTC 2022 suggested that herbarium specimens and ex situ collections could support plant de-extinction perhaps more easily than resurrecting extinct animal species via back-breeding, cloning and synthetic biology.

Dr. Hong Liu from Florida International University presenting her research at the IPTC 2022.

The importance for scientists to meet in conferences has been exacerbated over the past two years when the COVID pandemic confined conferences to virtual online events. While virtual conferences remain an important vehicle for exchange of scientific knowledge, the lack of personal interactions through interactive workshops, brainstorming through informal discussions, and social events can stymie engagement and collaborative development. As one of the first post-pandemic congresses to meet in person, the number of new connections and collaborations developed during the IPTC conference should spur many advancements in translocation science.

IPTC2022 attendees relaxing and chatting during the field trip in Castelluccio di Norcia (Central Apennines, Italy).

For example, originating from informal discussions at social events a large group of IPTC attendees are now preparing a manuscript on best practice guidelines for mitigation translocations. The conference also revived discussion about developing a global interoperable register and database of plant translocation – a feature that would undoubtedly accelerate synthesis and meta-analysis and surely benefit the international community. Finally, a special issue of Plant Ecology entitled “Advances in Plant Translocation” will be dedicated to articles derived from IPTC talks.

More broadly, the achievement of the first IPTC and the following editions, are expected to contribute to the United Nations 2030 Agenda that outlines the medium-term strategy to reverse the trend of global biodiversity loss, to integrate policies of sustainable exploitation of natural resources on which the well-being of the growing world population depends, and to reduce and mitigate conflicts between man and the environment. In particular, the IPTC conference will impact the Sustainable Development Goal 15 “Life on Land”, as well as the more specific United Nations initiative “Decade of Ecosystem Restoration”. The organising committee of the IPTC2022 is already at work to identify a suitable location for the next IPTC conference, ideally within the next two/three years. Stay tuned for more exciting news and developments.

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For more on translocations, see Translocating a threatened totem by Adam Cross

Conserving and restoring Missouri bladderpod, a US Midwestern endemic

Matthew Albrecht is a Scientist in the Center for Conservation and Sustainable Development at Missouri Botanical Garden. Here he describes a recent fieldtrip to the Ouchita Mountains to study outlying populations of the federally threatened Missouri bladderpod, Physaria filiformis.

Situated between Rocky Mountains to the west and the Appalachians to the east lies the often overlooked Ouachita (pronounced WAH-shi-tah) Mountains of central and western Arkansas and adjacent Oklahoma. Unlike the Rocky and Appalachian Mountains, the Ouachitas are a relatively small mountain chain that trends primarily east-west. Despite occupying a relatively small area, the Ouachitas harbor a large proportion of the region’s plant diversity and represent a remarkable center for endemism including many rare plants species with extremely narrow distributions.

On a recent spring afternoon, Christy Edwards and I had the opportunity to visit the relatively rare and poorly studied shale outcroppings of the Ouachitas with botanists Brent Baker and Diana Soteropoulos of the Arkansas Natural Heritage Commission. In the Ouachitas, shale formations outcrop on gentle to steep south- or west-facing slopes and occasionally on gently sloping drainages. Upon first glance, these outcroppings with exposed fragments of thin, black shale and patches of sparse vegetation cover appear somewhat other worldly. Upon closer inspection, one finds tucked between shale fragments a number of xeric-adapted herbaceous species capable of surviving in this harsh environment, where the dark, sun-scorched shale at the surface creates extreme ecological conditions.

Ouachita shale glade and barrens. Photo by Matthew Albrecht.

Xeric-adapted species specialize on the thinnest soil portions of shale outcrops. Photo by Christy Edwards.

Shale barrens and glades are mosaic plant communities consisting of a remarkable number of endemic, rare, and narrowly-distributed species. According to NatureServe, 36 plant species of state conservation concern and more than 20 globally critically imperiled, imperiled, or vulnerable species occur in this system. New species are still occasionally discovered and a few species remain undescribed in the Ouachita shale barrens. For example, we saw a striking purple-flowered undescribed species of wild hyacinth (Camassia sp. nova) during our visit.

An undescribed wild hyacinth (Camassia sp. nova) growing in a shale glade and barren complex owned and managed by the Ross Foundation. Photo by Matthew Albrecht.

The star of the show that day and the focus of our research expedition to the Ouachitas was the federally threatened Missouri bladderpod (Physaria filiformis).  Many members of the genus Physaria – commonly known as bladderpods due to their inflated seed pods – are recognized for their narrow distributions and edaphic endemism, or restriction to unusual soils. As a small-statured winter annual, Missouri bladderpod showcases brilliant yellow flowers in early spring and specializes on thin-soiled calcareous (dolomite and limestone) outcrops in northern Arkansas and southwestern Missouri. However, at its southern range limit in the Ouachitas, Missouri bladderpod is known from just a few isolated shale glades and barrens.

A profusion of flowering Missouri bladderpod (Physaria filiformis). Photo by Christy Edwards.

Missouri bladderpod (Physaria filiformis) displaying inflated fruits on a shale outcropping. Photo by Matthew Albrecht.

Prior to visiting the Ouachitas I wondered how a presumed calciphile like Missouri bladderpod existed on shale formations, which typically produce acidic soils. Perhaps like a few other species of rocky outcrops in the region – such as Sedum pulchelum (widow’s cross), and Mononeuria patula (lime-barren sandwort) which occur on both acidic and calcareous substrates – I surmised MO bladderpod may also tolerate a broader range of edaphic conditions than previously thought. However, I soon learned the shale outcroppings we visited were interbedded with limestone and supported other calciphilic indicator species such as Ophioglossum engelmannii.

A case of cryptic speciation in the Ouachitas

Once known only from limestone glades in southwestern Missouri, botanists over the years have discovered populations of Missouri bladderpod on limestone, dolomite, and shale outcroppings in scattered locations throughout Arkansas, denying Missouri’s claim of its only endemic species. A recent study led by Christy Edwards at the Missouri Botanical Garden examined range-wide (Arkansas and Missouri) genetic variation in Missouri bladderpod and the degree of genetic differentiation among populations on limestone, dolomite, and shale. Interestingly, genetic data showed isolation by distance – meaning that as geographic distance increased among populations so too did genetic differentiation. Most strikingly, the geographically isolated shale populations in the Ouachitas were highly genetically divergent from dolomite and limestone glade populations further north in Arkansas and Missouri. This strong pattern of genetic differentiation points to a possible cryptic speciation event in the Ouachitas and a previously unrecognized extremely rare species. On one hand, the genetic data was somewhat surprising given there are no obvious morphological differences among Ouachita shale populations and P. filiformis. Conversely, the data do support the remarkable pattern of narrow-endemism observed throughout the Ouachita Mountains. 

As we trekked across Arkansas for a few days – along with Brent and Diana who generously shared their time and expertise – collecting fresh material of Missouri bladderpod for a deeper research dive into whether morphological traits differentiate this previously unrecognized cryptic species in the Ouachitas, the need to conserve and restore glade habitat became ever clearer. At present, there are only three known Ouachita populations, making this cryptic species extremely rare and vulnerable to extinction. Many shale glade and barrens systems are now severely damaged or have been destroyed by mining activities. Fortunately, the largest population we visited consisted of thousands of plants scattered across a shale glade and barrens complex that has been restored and managed with fire and woody thinning by the Ross Foundation. In the absence of periodic, appropriately-timed prescribed burning, glades and barrens slowly become encroached with woody species that eventually choke-out sun-loving plants like Missouri bladderpod.

A large, restored shale glade and barrens complex in the Ouachita Mountains.

Other populations of Missouri bladderpod eek out an existence on small stretches of outcrops on roadsides or private property maintained as cattle pasture. These sites prove challenging to conserve and restore. Sadly, we did visit some sites where populations were barely surviving due to degraded habitat conditions. However, two sites we visited gave us a glimmer of hope that Missouri bladderpod will continue to survive and thrive. First was a newly discovered dolomite glade population on private property in north-central Arkansas. The property owners recently thinned woody vegetation and began prescribed burning to restore their glade and woodland ecosystem. When we visited, Missouri bladderpod was thriving after a recent prescribed burn. Similarly, the second site we visited on public property had been thinned and burned in recent years, resulting in a diverse plant community and flourishing Missouri bladderpod population. These success stories illustrate the importance of restoring degraded habitat to conserve our rarest components of biodiversity.

Population of Missouri bladderpod growing on a roadside dolomite outcropping and pasture in north-central Arkansas.

A degraded site with woody encroachment and a small, declining population of Missouri bladderpod.

A restored hillside glade with a thriving population of Missouri bladderpod.

To learn more about the Missouri bladderpod, read the new, open access paper by Christy Edwards, Matthew Albrecht and others.

How a rare plant provided clues to restoring a degraded ecosystem

Dr. Matthew Albrecht is an associate scientist in conservation biology in the Center for Conservation and Sustainable Development at Missouri Botanical Garden. He describes the ecology of the endangered Pyne’s ground-plum (Astragalus bibullatus).

Formed from the fossilized remains of an ancient tropical sea, the Nashville Basin encompasses the geographic center of Tennessee, stretching north to southern Kentucky and south to northern Alabama. Celebrated by some as the “home of country music,” many of us prefer to revel in the region’s unique flora and fauna associated with the globally rare limestone glades, or limestone cedar glades. Here, thin, rocky soils interspersed with flat, exposed limestone bedrock support sun-loving herbaceous plants adapted to the scorching temperatures and parched soils of summer followed by near-permanently saturated soils in winter. Trees and other woody vegetation struggle to take hold here, creating an open, desert-like ambience.

Limestone Glade in the Nashville Basin with Oenothera macrocarpa (Missouri evening primrose), a rare disjunct species, in bloom. Photo by Matthew Albrecht

Treasured for their unique flora, limestone glades feature over two dozen endemic or near-endemic species along with several unusual disjuncts – known mainly from grasslands far west of Mississippi River. Glade endemics such as Nashville Breadroot (Pediomelum subacaule) and Gattinger’s prairie clover (Dalea gattingeri), occur in open, shallow-soil communities dominated by C₄ annual grasses and C₃ winter annuals, including several members of Leavenworthia spp. Most of these glade-restricted species are widespread throughout the Nashville Basin. However, several of the disjuncts and endemics are extremely rare, such as the federally endangered Pyne’s ground-plum (Astragalus bibullatus). Known from just a few sites in a single-county, Pyne’s ground-plum teeters perilously close to the brink of extinction.

Gattingers prairie clover (Dalea gattingeri; top) and Nashville breadroot (Pediomelum subacaule, bottom), characteristic glade species in the Nashville Basin.

Pyne’s ground-plum in flower (top) and fruit (bottom). Photos by Matthew Albrecht

Why are Pyne’s ground-plum and a few other endemics and disjuncts so rare? At first glance, the obvious culprit appears to be habitat loss from the unrelenting sprawl of Nashville. Just take a drive from Nashville to Murfreesboro on I-24 and you will encounter an uninterrupted sea of strip malls and tract housing. In the late 1800’s, famed botanist Augustine Gattinger collected a specimen of Pyne’s ground-plum much farther north than where present-day populations are found, in a spot now inundated by the J. Piercy Priest Dam and Reservoir near Nashville. Constructed on the Stones River in the 1960s, the dam flooded thousands of acres for “recreational enjoyment” and hydroelectric power generation. Undoubtedly, other rare plant populations, unknown at the time, faced a similar fate. Over time, humans have abused many glades, using them as trash dumps or for off-road vehicle recreation, which could have also led to their demise.

Trash dump at a limestone glade with a Pyne’s ground-plum population. Photo by Matthew Albrecht.

Our long-term research with Pyne’s ground-plum also points to additional factors. In 2010, we began a demographic monitoring study on Pyne’s ground-plum populations to understand how we could reverse this species’ decline. Most remaining populations occupy slightly deeper soil pockets on glade edges where perennial C₄ grasses and forbs form narrow, linear bands that abruptly transition into impenetrable thickets of woody vegetation – mostly of eastern red cedar (hereafter “cedar”). In a few cases, Pyne’s ground-plum grows in small, rocky openings surrounded by dense, dark cedar-hardwood forest.

Monitoring Pyne’s ground-plum populations located in a glade edge (top) and small opening of a cedar-hardwood forest (bottom).

At the time, the long-standing paradigm was that Pyne’s ground-plum – and some other extremely rare plants like Trifolium calcaricum – thrive in the partial shade cast by these adjacent cedar trees and woody vegetation at the glade edge. As the story goes, some endemics were less hardy and required some shade as a buffer from the extreme microclimate on the thin-soil outcrops. Much of the early, pioneering work on glade ecology by Elise Quarterman and her students – described stable plant communities under edaphic control of the thin, rocky soil. As was typical of that era, they described plant communities on deeper soils according to classical climax theories of eastern deciduous forest succession.

However, several years of careful monitoring and experimentation in my lab began to reveal other factors at play. Initially considered an outlier, one of our monitored populations occurs beneath a utility right-of-way, which rapidly succeeds to woody vegetation in the absence of periodic mowing. Our data showed that plants here grew larger and usually produced far more flowers and fruits compared to shaded sites. After measuring soil properties, light availability, and other vegetation properties in permanent plots, our analyses indicated that the amount of woody vegetation cover rather than edaphic conditions drove growth and reproduction in Pyne’s ground-plum. Follow-up experiments conducted by then REU student, Rachel Becknell, confirmed light-conditions that mimic cedar resulted in reduced growth of Pyne’s ground plum.

Top: Pyne’s ground population growing under a utility line kept open by periodic mowing. Bottom: Permanent monitoring plot with Pyne’s ground-plum and associated species.  Photo by Matthew Albrecht.

With fresh eyes, we began to scrutinize the dense thickets of cedar at our study sites. Upon closer inspection, we noticed the occasional, gnarled, and open-grown (i.e., wolf tree) chinkapin or post oak jutting above the younger, even-aged thickets of redcedar. Chinkapin and post oaks grow slowly in these thin, rocky soils, but their low-lying branches in multiple directions suggest these wolf trees once grew in conditions more open in the distant past. Historical aerial imagery dating back to the 1950’s confirmed that some of these forested sites were once more open, with far fewer cedars.

We speculate that disturbances from prior land-use activities probably kept these deeper soil areas around glade openings in a more savanna-like or open woodland state. In their absence, opportunistic woody vegetation – especially fast-growing cedar – colonized all but the thinnest soils in the limestone glades. Over time, this led to the development of multilayered forests and dense shrub layers that now surround the thin-soil glade openings at many of our study sites.

Dense cedar thicket behind a small remnant population of Pyne’s ground-plum. Photo by Matthew Albrecht.

To dig a bit deeper in time, my colleague, Dr. Quinn Long, and I also examined early land survey records dating back to the late 1700’s. Surveyors would delineate property boundaries based on the tree species (i.e., witness trees). If no tree species were present, surveyors used stakes (or sometimes stacks of rocks) to mark off the property boundary. In the records we examined, eastern redcedar represented just 2% of all witness tree species while oaks and stakes represented a majority of the records. Now, cedars are probably the most abundant tree in the Nashville Basin.

Although we interpret historical data with caution, these multiple lines of evidence imply a historically more open landscape in the Nashville Basin with far fewer cedars. Cedars are fire intolerant, and we hypothesize that periodic fire – naturally set by lightning and Native Americans – maintained historically lower densities of woody vegetation and promoted grassland species surrounding the glade pavement openings. Genetic analyses by our collaborators Dr. Ashley Morris (Furman University) and colleagues show widespread admixture among populations of Pyne’s ground-plum, which also supports a historically open landscape mosaic that facilitated gene flow among remnant populations via pollinator or animal movement.

Prescribed fire at Couchville Cedar Glades and Barrens Natural Area. Photo by Todd Crabtree.

Admittedly, we were not the first to propose a paradigm shift in the ecology of the Nashville Basin. We soon realized a few other astute botanists long before us advocated for the use of fire management to create more open habitat around glades, but with limited data these recommendations never gained widespread traction among land managers or found their way into the scientific literature. Another issue was that ecologists and botanists tended to focus almost exclusively on the plant communities of open, thin-soil glades – which are clearly not fire-dependent – rather than on the matrix plant communities of slightly deeper soil surrounding them.

Not surprisingly, our ideas faced much skepticism and many questions: Hasn’t cedar always been the dominant tree of the Nashville Basin? After all, the Cedars of Lebanon State Park and State Forest – the largest remaining tract of Nashville Basin Glades and Woodlands under public protection – was named after the towering eastern red cedars that reminded early settlers of the Biblical cedar forests around Mount Lebanon.

At about the same time of our research discoveries, Dr. Dwayne Estes, botanist and Director of the Southeastern Grasslands Initiative, also began developing transformative ideas about the Nashville Basin. Like us, he hypothesized that the glades were historically embedded in a savanna and open woodland landscape rather than dense forests as they are now. Unfortunately, there are few historical descriptions of the Nashville Basin before early settlers radically altered the landscape via farming, pasturing, and logging. Estes speculates that lack of detailed naturalist descriptions of the Nashville Basin prior to the Civil War resulted in a misunderstanding of its historical condition. The earliest reports after the Civil War describe a largely forested region with large cedars, which could have easily developed over the 80-year period between the time of settlement and the mid-1800’s.

Long before settlement, we know that American bison and other large mammalian grazers also crisscrossed this landscape along ancient traces or megafauna highways that connected mineral licks and water sources. Formerly known as French lick, what is now present day downtown Nashville contained a large salt lick, once visited by herds of bison and elk according to early accounts. Disturbance associated with grazing and large-animal activity combined with periodic fire and drought probably kept the Nashville Basin in a more open state. Interestingly, Pyne’s ground-plum’s presumed closest relative, Astragalus crassicarpus, is widespread throughout grasslands in the Great Plains. Commonly known as buffalo pea, it also produces large plum-colored fruits eaten by Native Americans and presumably bison. In many years of monitoring, we rarely find that animals eat Pyne’s ground-plum fruits, which slowly dehisce releasing their hard seeds next to mother plants. Seeds contain a double seed coat making them challenging to germinate. After years of experimentation, we have found that exposing seeds to high concentrations of sulfuric acid followed by a short period of cold stratification results in consistently high germination compared to other treatments. We now wonder whether this germination strategy might be linked to ancient relationships with mammalian grazers who possibly dispersed the fruits and scarified the seeds.

How does Pyne’s ground-plum inform restoration of degraded woodland and savanna-like systems in the Nashville Basin? Thanks to the prodigious efforts of conservation agencies, several remnant limestone glades have been protected. However, until recently, the dense, cedar-hardwood forest surrounding open glades received little attention from land managers. In 2012, we along with collaborators at the Tennessee Department of Environment and Conservation (TDEC) and United States Fish and Wildlife Service began thinning woody vegetation in the most shaded Pyne’s ground-plum populations. After a few years, we noticed increased flowering at the most shaded sites. To reestablish a more open woodland and savanna-like structure in protected areas throughout the Nashville Basin, TDEC began widespread thinning of woody vegetation around glade openings and reinitiating the key ecological process of fire.

A recently restored area at Flat Rock Cedar Glade and Barrens Natural Area.  Pyne’s ground-plum (inside cages) was reestablished at this site in 2016 after mechanical thinning and fire removed woody vegetation at the glade edge.

On a warm, sunny afternoon this past October, my colleague, Noah Dell, and I set out to survey restored areas that might be suitable for establishing Pyne’s ground-plum populations. Hiking through recently restored areas we noticed grassland- and savanna-associated species slowly beginning to rebound and increase in abundance. Compared to previous years, it was much easier to find open, deeper soils on well-drained sites that are needed to reestablish Pyne’s ground-plum. With time and continued restoration of ecological processes, we are optimistic that this and many other rare species will continue towards path of recovery in the Nashville Basin.

Save me, Seymour! The increasingly dire plight of Darwin’s “Most wonderful plants in the world”

Adam Cross and Thilo Krueger describe the natural history and conservation of carnivorous plants. Adam is a research fellow at Curtin University , Western Australia and Science Director for the EcoHealth Network. Thilo is a masters student in Adam’s research group and is researching prey spectra and other plant-animal interactions of carnivorous plants.

Carnivorous plants are a unique and fascinating group that have captivated scientists and the public, as well as inspired writers and film makers, for well over a hundred years. During his seminal 1875 work Insectivorous Plants, while studying one of the sticky-leaved Sundews (Drosera), British naturalist Charles Darwin once famously and not at all exaggeratedly wrote “I care more about Drosera than the origin of all the species in the world”. These incredible species have flipped the traditional perception of plants as immobile producers, and possess highly modified leaves that have evolved to attract, capture and digest animal prey – mostly small insects, but for some species occasionally also birds and small mammals.

Drosera leioblastus (Droseraceae) is an example of a carnivorous plant species threatened by high-intensity or aseasonal fire events. An extreme bushfire north of Perth, Western Australia, in 2006 reduced the only known population at the time from several thousand individuals to eleven in 2008. As of 2020, just seven plants remain at this site. Photo: Thilo Krueger.

Capturing prey allows carnivorous plants to obtain nutrients in habitats where soils are extremely nutrient-poor, and they thrive in areas like swamps, rocky seepages and dripping rock walls, seasonally-flooded lowlands and even the canopies of tropical rainforests. Many species of these predatory plants grow in almost pure sand or in laterite soils, which are notoriously low in important nutrients for plants such as nitrogen and phosphorus. In these habitats, carnivory represents a very effective strategy for competition and survival.

A field of the stunning Sarracenia leucophylla growing in Long Leaf Pine savanna in Louisiana, USA – sadly, once-common sights like these are becoming increasingly rare as habitat continues to be lost. Photo: Adam Cross.

While there are several very well-known carnivorous plants, such as the Venus Flytrap (Dionaea) and Trumpet Pitcher Plants (Sarracenia) of North America, there are in fact over 860 species that are currently described world-wide. Incredibly, carnivory has independently evolved at least 11 times in different plant lineages, and at many different points in time. This evolutionary development has led to a wide diversity not only in the size and form or carnivorous plants, but also their function and biology. While some species are not much larger than a single grain of sand (such as the diminutive Utricularia simmonsii, one of the smallest of all flowering plants), the largest species are vines growing up to 60 m into rainforest canopies (Triphyophyllum peltatum). Many species are terrestrial, occurring in habitats ranging from mountain tops to Mediterranean scrubland to seasonally-wet swampland, and numerous species have become partially or even fully aquatic. Within tropical rainforests, there are even a number of epiphytic carnivorous plants – species growing high in the canopy on the mossy trunks or branches of trees.

The colourful and intricately veined pitchers of Sarracenia leucophylla, which apparently almost glow under moonlight and capture large numbers of night-flying moths. Photo: Adam Cross.

However, perhaps most incredibly, there are many different structures and methods that plants have evolved for carnivory. A range of genera, including Byblis (Byblidaceae), Drosera (Droseraceae), Drosophyllum (Drosophyllaceae), Pinguicula (Lentibulariaceae) and Triphyophyllum (Dioncophyllaceae) employ sticky leaves to capture prey, relying upon mucilage produced by specialized sessile or motile glands containing digestive enzymes to snare and absorb nutrients from insects. Philcoxia (Plantaginaceae) also produces sticky leaves, but holds these beneath the soil surface to capture small nematodes and other small subterranean fauna. Some species produce leaves modified to form pitchers of varying complexity with slippery walls to prevent the escape of captured prey, which drown and are digested in pools of water and enzymes (Brocchinia and Catopsis [Poaceae], Cephalotus [Cephalotaceae], Nepenthes [Nepenthaceae], and Darlingtonia, Heliamphora, Sarracenia [Sarraceniaceae]). Still others utilize quick-moving, snapping lobed traps (Dionaea and Aldrovanda [Droseraceae]), and many species even produce highly complex subterranean corkscrew and suction traps (Genlisea and Utricularia [Lentibulariaceae]). Some of these structures are capable of making among the fastest movements in the plant kingdom.

The critically endangered carnivorous plant Byblis gigantea (Byblidaceae) growing in a wetland near Perth, Western Australia. This species has suffered dramatic population declines in the last 30 years, losing approximately two thirds of all recorded subpopulations to urban development. Photo: Thilo Krueger.

A number of carnivorous plants also exhibit amazing biological mutualisms, being rather paradoxically reliant upon animals for their growth and survival. Roridula (Roridulaceae) produces sticky resin from glands on its leaves, but lacks the capability to produce any digestive enzymes and instead relies upon a unique digestive mutualism with a Hemipteran bug (Pameridea species) to absorb nutrients from captured prey, as these bugs can move among the resinous glands without being captured and defecate onto the leaf surface. Similar digestive mutualisms are known for Hemipteran bugs of the genus Setocoris with Byblis and some species of Drosera. The digestive fluid of the pitcher plant Cephalotus follicularis provides crucial breeding habitat for a species of stiltfly (Badisis ambulans), while Nepenthes hemsleyana provides a safe roosting site for Hardwicke’s bat and in return benefits from digesting the ablutions of roosting bats in addition to capturing insect prey. Other Nepenthes, such as the Bornean N. lowii, produce an appealing food for tree shrews on the underside of the pitcher lid, which has a laxative effect and results in the shrew depositing a package of nutrients into the pitcher ‘latrine’ in return for the feed. It has even been proposed that the squat pitchers of Nepenthes ampullaria, which are open to the rain and catch falling leaf detritus, could be vegetarian.

Nepenthes albomarginata growing in Malaysia. Photo: Thilo Krueger.

These predatory plants can be found on every continent except Antarctica, but there are distinct “hotspots” of carnivorous plant diversity in South America, South Africa, Southeast Asia and Australia. Almost a quarter of all currently described carnivorous plants can be found in the ancient, nutrient-poor landscapes of Western Australia, for example. Unfortunately, many of these areas are also experiencing some of the world’s highest rates of habitat destruction – in the southwest of Western Australia, where approximately 120 species of carnivorous plants occur, approximately 70% of all native vegetation (and up to 97% in some regions) has been cleared for agriculture and urban development. What little native vegetation remains is often isolated, heavily fragmented, and significantly degraded from weed invasion and poor fire management.

Carnivorous plants have been described as harbingers of ecosystem integrity, as they are often the first to disappear after disturbance. As might be expected given their unique ecologies, most carnivorous plants have very small ecological niches and are extremely sensitive to environmental change. Given that they often rely on habitats such as nutrient-poor wetlands, which are particularly vulnerable to human impacts and represent some of the most threatened ecosystems globally, carnivorous plants face an existential threat in the 21^st Century.

The summit of Mt Roraima, a tepui in Venezuela, isolated from the surrounding savanna by 800 m high cliffs and harbouring numerous species of carnivorous plants including species of the unique Sun Pitchers (Heliamphora). Photo: Adam Cross.

A recent international study by Cross et al. (2020) examining the conservation status and threats faced by carnivorous plants found approximately a quarter of all species around the world were at risk of extinction. The highest numbers of critically endangered species occurred in Australia, Brazil, Indonesia, Philippines, Cuba and Thailand – in many cases, the same areas regarded as the most significant hotspots of carnivorous plant diversity. Importantly, 89 species of carnivorous plants (over 10% of all species) are only known from a single location, making them particularly vulnerable to any disturbances, and particularly rapid impacts, to their habitats.

Nepenthes fusca, a tropical pitcher plant, growing in a dense peat-swamp forest remnant in Malaysian Borneo. Photo: Adam Cross.

Due to their unique insect-capturing traits and often spectacular appearance, many carnivorous plants are very popular with horticulturists and hobby plant collectors. Unfortunately, this has created a significant market for illegal collection – also known as poaching – of carnivorous plants and several species have already been driven to the brink of extinction by poachers. Pitcher Plants such as Tropical Pitcher Plants from south-east Asia and the Albany Pitcher Plant from Western Australia are particularly affected by poaching but even the iconic Venus Flytrap from the United States continues to be plagued by unscrupulous poachers. There must be immediate and concerted global action to cease the illegal collection of wild plants, and much greater regulatory enforcement of biodiversity protection laws to end carnivorous plant poaching.

The snapping traps of the Venus Flytrap, Dionaea muscipula, on individuals growing in open wet savanna at one of the increasingly few remnant populations of this iconic species in North Carolina, USA.

Cross et al. found that the continuing clearing of natural vegetation for agriculture, urban development and mining projects represented by far the most severe and immediate threat to carnivorous plants. In just the past two decades, massive areas of pristine habitat have been converted into oil palm plantations in Southeast Asia, cattle farms in Brazil, or suburban housing and industrial development in Australia. For example, two of the last remaining populations of the Critically Endangered rainbow plant (Byblis gigantea) in Perth, Western Australia, were destroyed for the construction of a liquor supermarket and a logistics distribution centre. Several populations of sundews (Drosera) near the town of Hermanus, in South Africa, are rather paradoxically being lost to the development of a settlement known as “Sundew Villas”. Much stronger protections are required to ensure that remnant carnivorous plant habitats are protected and conserved.

One of the World’s rarest carnivorous plant species, Drosera oreopodion, from Perth, Western Australia. This critically endangered species is known from only a few hundred plants in an area just a few square metres in size. The population is situated in a narrow and unmanaged railway reserve, threatened by weed infestation, disturbance and fire events. Its population count continues to shrink, and one fire or clearing event would likely cause immediate extinction. Photo: Thilo Krueger.

Climate change poses another significant threat to carnivorous plants, especially the many species occurring in Mediterranean climate regions where warming, drying trends are already becoming evident. Extreme and prolonged drought conditions, such as have been recently experienced in many Mediterranean climate regions around the world, can not only impact directly upon species and communities, they can also fuel high-intensity and aseasonal fires. Although fire forms a natural part of the ecology of many ecosystems in which carnivorous plants occur, fire regimes have been increasingly altered by climate change and inadequate fire management practices. The effect of altered fire regimes on carnivorous plants is complex, idiosyncratic and often still poorly understood; while some species (especially geophytes such as tuberous Drosera) may benefit from high-intensity fires that remove competition from other vegetation, the same fire can have devastating impacts on other species lacking underground structures for resprouting. For example, an extreme summer bushfire in 2006 near Perth, Western Australia, fuelled by record drought conditions at the time, reduced the only known population of the critically endangered Drosera leioblastus from several thousand individuals to just 11 plants, while simultaneously inducing mass-flowering of most tuberous Drosera in the same area. The complex effect of fire and the need for sound fire management policies is highlighted by the Albany Pitcher Plant (Cephalotus follicularis), which is threatened both by prescribed burning at short fire intervals as well as long-term fire suppression. Weed invasion can further exacerbate fire management, and Cross et al. (2020) suggest that simultaneous prioritisation should be afforded to invasive species management and the maintenance and preservation of natural ecosystem processes such as fire regimes and hydrological functioning.

The iconic Cephalotus follicularis (Albany Pitcher Plant; Cephalotaceae) from south-west Western Australia produces highly modified cup-shaped leaves filled with a mixture of water and digestive enzymes. Prey is captured by falling into the trap (which features slippery walls and inward pointing “teeth” to prevent escape). After drowning in the digestive fluid, the plant will absorb the prey’s important nutrients such as nitrogen and phosphorus. Photo: Thilo Krueger.

Ecological restoration offers not only hope for the return of many carnivorous plant species to regions from which they have been lost, but also an effective mechanism by which ecosystem functioning and natural processes like fire and hydrology can be reinstated in degraded landscapes where these processes have been impaired. While there is growing urgency to conserve what little natural carnivorous plant habitat remains, Cross et al. (2020) highlight the growing imperative to begin scaling up restoration efforts in areas where habitat loss and ecosystem disturbance have been most severe, in order to concomitantly provide new habitat for these species and provide buffers for protected areas. Far too often remnant habitats are not only highly fragmented but also abut farmland or urban developments, and the restoration of ecological corridors and buffer zones will confer resilience and greater ecological integrity to these increasingly beleaguered ecosystems.

The loss of carnivorous plants would not only be a devastating loss for future generations, but could potentially have detrimental effects across ecosystems. They have captivated scientists and the public for hundreds of years, from their portrayal as horrifying monsters in popular films to providing inspiration for the development of non-stick surfaces. But they are integral parts of ecosystems, important cogs in the complex biodiverse systems in which we live and upon which we rely, and we must preserve them. The number of vulnerable, endangered and extinct species continues to grow despite conservation efforts around the world, and it is clear that we must begin investing significantly in the restoration of carnivorous plant habitats, particularly in regions such as Australia, Brazil, South Africa, southeast Asia and North America, if they are to survive for future generations to marvel at.

Sarracenia flava growing in Florida, USA. Photo: Thilo Krueger.

Our global review of the conservation status of carnivorous plants can be read in full, open access, here. To learn more about the unique and incredible biology of our carnivorous plant heritage, see a recent international monograph about their ecology, biology and evolution to which the present authors were contributors. The authors have also recently written books on some of the most amazing carnivorous plant species, including the Waterwheel Plant, Aldrovanda vesiculosa and the Albany Pitcher Plant, Cephalotus follicularis.

Plant diversity, soil carbon, and ecological restoration in Virginia grasslands

Kathlynn Lewis is an undergraduate researcher in the School of Plant and Environmental Sciences at Virginia Tech. She is studying soil carbon storage as part of a larger project on grassland floristics, conservation, and restoration in northern Virginia. Keep up with her research on Twitter by following @KathlynnLewis.

How many rare or “cool” plants do you drive by every day without noticing? Do you brake for Buchnera americana? Do you pull over for Pycnanthemum torreyi? This is something not a lot of people think about, and I didn’t think about either until very recently. The answer is that there are more cool plants along roadsides than you would think. Some of the rarest grassland plants in Virginia have found a home in roadside clearings and powerline cuts where regular removal of trees has created an opening for them to grow and sometimes thrive.

This summer the Virginia Tech Restoration Ecology Lab team has been hard at work doing plant and soil surveys in several counties of northern Virginia. We are partnering with the Clifton Institute and Virginia Working Landscapes to find out where these rare grassland plants can be found and what are the greatest threats these populations face.

American bluehearts (Buchnera americana) – a charismatic hemiparasite and rare denizen of high-quality Virginia grasslands. Photo by JL Reid.

Many of the native vegetation surveys have taken us to the locations people might expect to find high-quality grassland plants, such as parts of Manassas Battlefield National Park where the soil and ecosystem have remained relatively undisturbed for almost 80 years. Other areas are much less expected. Rare plants also show up in power line right of ways and strips of roadside with tire tracks crisscrossing them in every direction and markers stuck in the ground indicating the soil was completely displaced to bury utility lines.

A flourishing native grassland at Manassas National Battlefield Park. In July, it was bedazzled with the hot pink inflorescences of scaly blazing star (Liatris squarrosa). Photo by JL Reid.

A hidden gem – high diversity native grassland along a back road in Culpeper County. The two lines show our 50 × 2 m sampling transect. Photo by JL Reid.

During June, we collected samples from 29 sites to compare plant species diversity with the amount of carbon stored in the soil. We also sampled soils from grassland restoration plantings and pastures “improved” with tall fescue (Schedonorus arundinaceus) to compare the effect of different management practices and ecological restoration on soil carbon sequestration. The soil work is my part of the project. My prediction is that soil carbon storage will be greatest in diverse, native grasslands and lowest in degraded fescue fields. I expect that restored grasslands will be intermediate.

A “blackjack” soil sample from a power line right of way in Culpeper County. This soil had so much clay you could pull it out of the probe and tie it in an overhand knot. Photo by JL Reid.

Power line right of ways are an interesting focus of this study because they present both opportunities and challenges for plant conservation. Power companies keep these areas open by cutting out trees and spraying young sprouts with herbicide. This management is the only reason that grasslands exist in these places today, but the rare plants that live there are at constant risk of collateral damage. At least two of the areas that we sampled in June were sprayed in July, harming populations of rare plants like Torrey’s mountain mint (Pycnanthemum torreyi) and stiff goldenrod (Solidago rigida).

Rose-pink (Sabatia angularis) next to a power line right of way in Prince William County. This plant can give away a good grassland even at 60 miles per hour. Photo by JL Reid.

The vegetation surveying team has already observed over 450 species across the 29 sites sampled. Not all of these species are a welcome presence though. Invasive species appear to pose one of the largest threats to Virginia grassland ecosystems we have observed in the field. A newly emerging and particularly aggressive invader is joint-head grass (Arthraxon hispidis) which we have found in many of the sites we are sampling. This annual grass is similar to Japenese stiltgrass (Microstegium vimineum) but there is very little information about its effects on grassland ecosystems or methods for controlling it.

Joint-head grass (tan-colored thatch) smothering one of the most diverse grasslands in northern Virginia. Photo by JL Reid.

The plant survey team is now doing a second round of sampling to identify later-blooming species, and they are collating information about the land use history at each of our study sites. The soil samples we collected are currently being analyzed (by me) in a lab at Virginia Tech. We will start analyzing data in the fall and hope this summer’s fieldwork will help inform future research projects and the conversation around land management in Virginia grasslands.

The author collects a panic grass (Dichanthelium sp.) for further observation. Photo by JL Reid.

To find out how ecological restoration affects grassland soil carbon storage in northern Virginia, follow the author on Twitter @KathlynnLewis.

Cactus conservation and restoration of arid environments in Central Mexico

En route to attending the 4th meeting of the Ecological Restoration Alliance of Botanic Gardens Conservation International, in Xalapa, Veracruz, Mexico, James Aronson stopped off to visit Beatriz Maruri Aguilar, a recent Bascom Fellowship recipient who works as Scientific Research Coordinator at the Cadereyta Regional Botanic Garden, and her colleagues, Director Emiliano Sanchez Martinez, and Research assistants Hailen Ugalde de la Cruz and Hugo Altamirano Vázquez in Cadereyta de Montes, Queretaro, north of Mexico City. Beatriz and Hailen describe the Garden’s work conserving an endangered, endemic cactus, and an innovative restoration project.

Main entrance to Cadereyta Regional Botanic Garden

Cadereyta de Montes is close to the southern end of the Chihuahuan Desert, in the semiarid zone of Queretaro and Hidalgo. The place is relevant for biodiversity because of its number of endemic arid plants. However, today some habitats have been definitively altered and several special plants are on the brink of extinction.

One of those emblematic species, popular among succulent plant collectors around the world, is under severe threat to its survival. Worldwide growing successfully in cultivation, Mammillaria herrerae Werderm. is facing tough conditions and could eventually disappear from its original habitat. Scientists from the Cadereyta Regional Botanic Garden have done a survey which indicates that there are only a few hundred individuals remaining in the wild, that the species shows very low recruitment by seed, and that seedlings grow on rocky substrates beneath nurse plants.

Expedition day: James and Beatriz descend the slopes where Mammillaria herrerae lives. Photo by Hailen Ugalde de la Cruz.

Observing the remaining individuals is a shocking experience that moves to reflection.

They look small and fragile, but these geometric, almost spherical, plants are a beautiful example of the precision of nature, which gives each organism the characteristics it requires to survive in its natural habitat.

The beautiful Mammillaria herrerae Werderm., also known as “golf ball cactus” or “bolita de hilo” (small ball of thread). Photo by Beatriz Maruri Aguilar.

Densely covered with white spines and half-buried in the rock, Mammillaria herrerae hides its presence in the limestone soil. Its densely-distributed spines also help harvest fog at this elevation, where atmospheric moisture can condense. In an arid region like central Mexico, such adaptations provide species with strategies to reach the vital element.

A small group of Mammillaria herrerae struggle to persist on the steep slope. Photo by Hailen Ugalde de la Cruz.

Their permanence wouldn’t be menaced, but infrastructure development has reached them.

The pipes of the “Acueducto II” Hydraulic system climb more than 1200 meters to reach an elevated point from which it carries water by gravity to Queretaro City. Photo by Beatriz Maruri Aguilar.

In such a challenging environment, the construction of this infrastructure has severely damaged the landscape where Mammillaria herrerae lives. Photo by Beatriz Maruri Aguilar.

As the aqueduct was constructed over several years, several efforts were conducted to relocate bigger native plants. Photo by Hailen Ugalde de la Cruz.

Efforts will continue. The Cadereyta Regional Botanic Garden team will conduct a 2-year demographic study, study the floral biology of the species, and describe plant community biodiversity at the specific distribution points. Stock propagation at the Garden will continue. The path is being prepared to, one day, return these jewels to their place in their natural environment, and to protect them better in situ.

Hailen Ugalde (left), Hugo Altamirano (center), and Beatriz Maruri (right), the staff of the Cadereyta Regional Botanic Garden, visit a remnant population of Mammillaria herrerae . Photos by James Aronson (left) and Hailen Ugalde de la Cruz (right).

The landscape around M. herrerae’s natural habitat. The mountain in the background is the southern facies of the Sierra del Doctor, part of the Sierra Madre Oriental. Photo by Hailen Ugalde de la Cruz.

Some of the globose companions of Mammillaria herrerae Werderm. Left: Astrophytum ornatum (DC.) Britton & Rose; Right: Mammillaria parkinsonii Ehreb. Photos by Hailen Ugalde de la Cruz.

“An unusual model of assisted ecological restoration”

At first sight, the arid scenery of the surroundings of the small city of Cadereyta, in Queretaro, Central Mexico, could transport us to past times.

Panoramic view from Cadereyta de Montes, and the ancient flavor of the streets. Photos by José Belem Hernández Díaz.

However, this semi-urban and semi-rural zone combines the features of ancient Mexican villages and landscapes with the unmistakable signs of the transformation that progress usually brings.

The peripheral landscape of Cadereyta de Montes (14,000 inhabitants) is showing signs of transformation. The urban area is gradually displacing the agricultural parcels and the native flora, giving rise to an interface formed of irregular patches that combine new houses and small agricultural parcels. A third type of ground, neither agricultural nor urban, is also present. This type of land is isolated from wild and agricultural areas, and can degrade easily.

The polygon of the Cadereyta Regional Botanic Garden, highlighted in yellow, in the vicinity of Cadereyta de Montes. Map prepared by Beatriz Maruri Aguilar.

In additional to its formal collections and buildings, the Cadereyta Regional Botanical Garden maintains an area that exemplifies the conditions found in much of the surrounding semi-arid region. Xerophytic shrub-dominated matorral is the main vegetation type which is generally highly degraded by human activities over the last decades, and surviving remnants in good ecological condition are only found quite isolated from agricultural areas. The vegetation comprises an interesting assemblage of native species in the Asteraceae, Poaceae, Solanaceae, Verbenaceae, Euphorbiaceae, Cactaceae, Fabaceae and other families, many of which are struggling to survive within large patches of invasive grasses.

A view from the top: looking down at degraded land to be managed by the Botanic Garden. Photo by Hailen Ugalde de la Cruz.

Another view from the top: Hugo, Beatriz, and James observe the transformed landscape of Cadereyta de Montes from one of the Garden’s balconies. Photo by Hailen Ugalde de la Cruz.

In this area, the Botanic Garden is working on restoration models that will be of interest – and direct use – to local landowners. It is an unusual model of assisted ecological restoration, with an agroforestry approach. The core idea is that through the implementation and monitoring of native vegetation and economic plant mosaics, it should be possible to combine conservation of biodiversity, sustainable development for small farms, and ecological restoration of degraded lands.

The pilot project will have two different types of parcels for comparative and demonstration purposes. One type will be built following an ecological approach to restoration, using only native plant species; the other will have an agroforestry approach, combining a group of native species with some selected edible/useful species. The area of the plots where the two strategies will be implemented will be prepared by removing an invasive species of grass (Melinis repens Willd. (Zizka), or “pink grass”). The agroforestry model will also generate useful products, such as agave leaves, which are used in the region for several purposes including to make pulque – an ancient beverage made by the fermentation of the agave sap, highly popular in this region. This model will also include aromatic plants – such as the asters Matricaria chamomilla L. and Calendula officinalis L. and the mint Salvia sp., as well as other useful plants as the euphorb Jatropha dioica Sessé, “sangregado”, commonly used as an ingredient in shampoos and formulas against gray hair.  These human uses are valuable in areas like this, where some human populations are suffering from an elevated degree of marginalization. The Cadereyta Regional Botanical Garden has developed propagation protocols of native species, and part of the stock produced will be used in the model described.

Some of the stock of native species produced at the Cadereyta Regional Botanic Garden. Photos by Beatriz Maruri Aguilar (top) and Hugo Guadalupe Altamirano Vázquez (bottom).

At Cadereyta de Montes, some areas need a helping hand to keep the landscape in good shape. Other places hide extremely valuable living treasures that are currently struggling for survival. The Cadereyta Regional Botanic Garden is working every day to contribute to the conservation of the highly remarkable flora of the southern end of the Chihuahuan Desert, as well as to offer sustainable solutions for landscape use in a transforming environment. This way, the Garden intends to become an active participant for the achievement of Mexico’s goals for plant conservation.