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, loosing 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 21st 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.

Restoring Tallgrass Prairies across Iowa

Andrew Kaul is a new Restoration Ecology Post-doc in the Center for Conservation and Sustainable Development at the Missouri Botanical Garden. Here he describes some projects from his dissertation work conducted with Brian Wilsey at Iowa State University.

Tallgrass prairies once covered most of the central United States, but much of this historic ecosystem was lost to agriculture during the 19th and early 20th Centuries. Iowa sits at the heart of the tallgrass prairie range and lost more of its prairie than any other state except Illinois.

Throughout the Midwest, prairie restoration efforts have become increasingly common, and after several decades of research, the practice of prairie restoration has become increasingly complicated. We now know that restoration outcomes can be highly variable, and it is difficult to predict the outcome of any given restoration because there are so many factors that have been documented to influence restoration success, in terms of species diversity and establishment of target species from the seed mix.

Nodding lady’s tresses (Spiranthes cernua) at Doolittle prairie in Story Co, Iowa. Conservative taxa from groups like orchids are common in remnants, but are often missing from restored prairie communities.

For my PhD at Iowa State I studied 93 grassland restoration projects across Iowa. Previous work on grassland restoration had included careful experiments and thorough investigations of novel restoration techniques. What hadn’t been done before was to treat existing restorations each as their own little experiment and to sample broadly across the wide diversity of restorations in the real world. This approach allowed us to describe general patterns across many sites and to investigate which of the many potentially important processes tended to drive restoration outcomes.

With this project, my advisor Brian Wilsey and I sought to test which factors are the best predictors of restoration success in terms of species diversity, degree of invasion, and establishment of sown species. We considered factors including management history, the diversity of the seed mix, land use history of the site, site size and shape, soil characteristics, and weather during the first couple years of vegetation development. We took a retrospective approach to answer these questions, using existing restorations, which were highly variable in their age and how they were undertaken. We sampled vegetation at 93 restoration sites across Iowa over two summers and interviewed the managers of each of those sites afterwards to get information on when the restoration was started, what seed was used, and how it had been managed. We also sampled 5 prairie remnants, as a reference.

Here I am squinting on a sunny day in July of 2015, posed next to a glacial boulder at one of the remnants in our study – Cayler prairie in Dickinson Co, Iowa. (Photo credit: Brian Wilsey)

We found that by far the strongest predictor of plant diversity and recruitment of species from the seed mix was the degree of invasion by exotic species, where the more heavily invaded a site was, the lower the plant diversity and recruitment of target species. The influence of exotic species was more important than soil type, site management, restoration age, or any other aspects of the restoration, indicating control of exotic species is key to restoring prairies, and other temperate grasslands. The degree of invasion was higher in more linear shaped sites, sites with higher soil organic matter, and sites with fewer species in the seed mix, so we found that these variables were negatively related to our restoration success measures because of their indirect effects through exotic species. More linear habitats tend to have more “edge effects” where there are more colonization opportunities for exotic species. The higher invasion rates we found in sites with greater soil organic matter indicate the exotic species are better able to take advantage of nutrient availability. The lower invasion rates in sites seeded with more prairie species indicate that these mixes contain species that together, occupy more niche space and leave less open niches for exotic species to colonize. We also found that sites mowed during the first two years of establishment had higher diversity and establishment of sown species. This practice is supposed to suppress the annual weeds, which start growing before the seeded prairie species can establish.

Roadside prairie plantings have become a common example of restoration in Iowa.
Sown natives, purple coneflower (Echinacea pallida), and beebalm (Monarda fistulosa) are seen in this roadside prairie planting, which has become mostly dominated by European smooth brome (Bromus inermis).

Another goal of this project was to examine the ecology of milkweeds in prairie habitats. Milkweeds are obligate host plants for larvae of the monarch butterfly (Danaus plexippus), and in recent years, conserving and restoring milkweed populations in service of monarchs has become a major conservation priority in North America, especially in the Midwest, where many of the migratory monarchs breed. We counted milkweed stems within a meter of our sample quadrats at each prairie, and used these count data to examine what prairie habitats have the highest milkweed abundances, and what features of a prairie habitat best predict stem density. Specifically, we tested whether stem densities were different between remnant prairies, roadside restorations, and the non-roadside “conservation” restorations, most of which are managed by the Iowa Department of Natural Resources.

Common milkweed (Asclepias syriaca) is abundant in roadsides, and often establishes in restored areas as a volunteer native.

Milkweeds were far more abundant in remnants than restorations. Among restorations, roadsides had higher milkweed densities. Remnant prairies also had a higher diversity of milkweeds, so they are clearly an important habitat for this forb assemblage. Most of the milkweeds we sampled in restorations were common milkweed, even though it is rarely planted. On the other hand, Swamp milkweed (Asclepias incarnata) and butterfly milkweed (Asclepias tuberosa) are often included in restorations seed mixes, but were not nearly as abundant as volunteer common milkweeds.

Across all the restorations, we tested whether milkweed stem density was related to management (burning and/or mowing) or environmental variables including soil characteristics, plant diversity, degree of invasion, and site shape (linearity). We found that milkweeds were more abundant in more linear and invaded sites, and sites with lower soil density, and higher soil pH. These factors indicate that milkweeds are more abundant in areas with more soil disturbance. This is not surprising, considering the “weedy” ruderal nature of many milkweeds, especially common milkweed. The relationship with pH was a novel discovery, and future work will be needed to experimentally test whether milkweed germination or growth is higher in more basic soils, which is what our study indicates.

I am continuing my research on tallgrass prairie restoration with new projects examining plant functional traits to help understand why certain species are under- or over-represented in restorations. We have collected data on plant and leaf functional traits for over a hundred prairie plants and will test how the mean traits of plant communities differ between seed mixes, restorations, and remnants. Additionally, I am working with the Wilsey Lab on a related project examining phenological differences between plant communities in remnant and restored prairies.

Bottle Gentian (Gentiana andrewsii) is being measured for plant height at Doolittle Prairie (Story Co., Iowa) as part of an ongoing project to examine how traits of prairie plants differ between remnants and restored communities.

To learn more, follow me on Twitter @andrew_kaul and check out our milkweed paper in Restoration Ecology. The prairie restoration study was recently accepted in Ecological Applications, under the title, “Exotic species drive patterns of plant species diversity in 93 restored tallgrass prairies.” Look for it to come out soon!

Botanizing a Central Appalachian Shale Barren

Leighton Reid describes a field trip to a unique, natural community with Tom Wieboldt, retired curator of the Massey Herbarium at Virginia Tech.

From southwestern Virginia to central Pennsylvania, ancient shale formations jut out of the mountains at wonky angles. Loose and crumbly, the rocks bake in the sun. Surface temperatures can reach 60° C (140° F) – comparable to a desert. Rocks slip and tumble easily on the steep slopes. Few eastern plants are tough enough to hack it under these conditions. Among those that can, a few are globally unique.

On a warm day in August, I had the opportunity to botanize one such place – a central Appalachian shale barren in Craig County, Virginia – with Tom Wieboldt, retired curator of the Massey Herbarium at Virginia Tech (VPI), and a leading authority on shale barren flora. As we hiked and photographed plants, we talked about the conservation and potential for ecological restoration of these rare communities.

Shale barren wild buckwheat (Eriogonum allenii), a central Appalachian endemic whose relatives are mostly west of the Mississippi.

The gems of the shale barrens are the endemics. Amazingly, 22 species are found mostly or exclusively on central Appalachian shale barrens. Another seven species are rare or disjunct from the rest of their range – typically far to the west. For example, the closest population of chestnut lip fern (Cheilanthes castanea) outside of Virginia and West Virginia is in Oklahoma.

Virginia white-haired leatherflower (Clematis coactilis), a Virginia endemic and one of three leatherflowers endemic to central Appalachian shale barrens.
Shale-barren ragwort (Packera antennariifolia) had already finished flowering by August, but its leaves lived up to their name, looking very much like pussytoes (Antennaria sp.). This plant is strictly endemic to shale and metashale barrens.
Kates Mountain clover (Trifolium virginicum) was long thought to be a shale barren endemic, but it also occurs (rarely) on other substrates.
Shale barren evening primrose (Oenothera argillicola), a strict shale barren endemic.
The teeny-tiny flowers of mountain nailwort (Paronychia montana), a plant that is not quite endemic to shale barrens. It also occurs on a variety of other substrates.

Shale barren plant communities exist in a dynamic equilibrium. The steep, brittle shale formations often are under-cut by rivers, which carry away rocks and cause further erosion. In essence, the entire slope is constantly slipping downwards. Successful plants find the most stable areas and send down deep roots to try to keep their place on the rocky conveyor belt.

Why do shale barrens occur only in the Central Appalachians and not also in the Southern Appalachians? Tom gave me two reasons. First, the shale deposits in the Central Appalachians get thinner south of Montgomery County, Virginia, where Virginia Tech is located. Second, the high Allegheny Mountains in West Virginia create a rain shadow over parts of the Central Appalachians, more so than the more southern and shorter Cumberland Mountains. Drier conditions in the Allegheny rain shadow contribute to the shale barrens’ uniquely western ambiance.

Inhospitable as they are, shale barrens are not immune from human pressures. They are sometimes crossed by roads or utilities, and shale banks are sometimes quarried for road-building material. Livestock and overpopulated white-tailed deer browse the plants and catalyze erosion, while also adding nitrogen and foreign seeds to the sparse soil.

Craig Creek undercuts several shale bluffs, hastening their erosion and creating the conditions for shale barren plants to flourish.

Can disturbed shale barrens be restored?

When Reed Noss visited a Virginia shale barren for his book Forgotten Grasslands of the South, he found traversing the slippery slopes, lurching from one scattered red cedar to another, “close to suicidal”. I had similar thoughts following Tom up the mountainside. He climbed like a mountain goat, wandering out on thin ledges to collect interesting looking mosses.

Tom Wieboldt collects an interesting-looking moss from the side of a crumbling cliff.

As we walked, Tom wondered aloud whether it would even be possible to restore such a fragile plant community if it was destroyed. Wouldn’t it be better just to leave these places alone?

Undoubtedly leaving these places alone would be better. But I enjoyed thinking about how one might restore a shale barren that had already been destroyed – by quarrying, for instance. A first step might be to recontour the slope, aiming to reestablish a dynamic equilibrium with some areas eroding more actively than others. Perhaps this could be done by a skilled operator with some of the same quarrying equipment that had previously exploited the loose shale.

To revegetate such a place would require a source of propagules. I am teaching a course on Plant Materials for Environmental Restoration, so I put it to my students to find out whether shale barren plants were available from two major conservation seed suppliers. The results were not promising. Out of 86 native, non-woody angiosperms found in central Appalachian shale barrens*, less than a quarter (23.3%) could be purchased from any major seed supplier, and only 2.3% were available as seed collected from Virginia. None of the endemics were available.

As far as I can tell, few shale barren restorations have been undertaken, but I did read about one attempt in a shale barren in Green Ridge State Forest, Maryland. Whereas some shale barrens are actively threatened by acute pressures, like quarrying, this small (0.6 ha) barren was passively threatened by steady encroachment from the surrounding forest. Trees, especially pignut hickory (Carya glabra), were growing into a formerly open barren, stabilizing the soil and cutting off direct sunlight to plants closer to the ground. Managers restored the site in 2010-2011 by removing some of the pignut hickories and by burning the area during the winter. Together, these actions resulted in greater herbaceous vegetation cover and greater species diversity.

Central Appalachian shale barren, Craig County, Virginia, with a mix of shale barren wild buckwheat (Eriogonum allenii) and hairy lip fern (Cheilanthes lanosa) dominating the foreground.

Thanks to Tom Wieboldt for a fun field day, an excellent guest lecture, and stimulating discussions about botany, conservation, and restoration. To learn more about this unique natural community, read Tom’s co-authored chapter about shale barren communities in Savannas, Barrens, and Rock Outcrop Communities of North America, or Reed Noss’s chapter on shale barrens in Forgotten Grasslands of the South.

*For the seed availability exercise, we used the list of plants recorded by the Virginia Natural Heritage Program in their description of Central Appalachian Shale Barren (Shale Ridge Bald / Prairie Type) CEGL008530. We excluded woody plants, non-native plants, and ferns.

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.

Healthy Societies built from Healthy Ecosystems: How Australia and Aotearoa New Zealand are Working at the Intersection of Human Health and Ecological Restoration for a Healthier World

Adam Cross (Curtin University), Kiri Wallace (University of Waikato), and James Aronson (Missouri Botanical Garden) discuss the newly formed Four Islands EcoHealth Network, a regional coalition allied with the global action initiative EcoHealth Network, which aims to increase the amount and effectiveness of ecological restoration throughout the world. The new papers they discuss are published in the journals EcoHealth and Restoration Ecology.

We live in an age of environmental challenges and crises that require societies to sit up and pay more attention to how they function. From heatwaves and water shortages to megafires and sudden floods (sometimes one after the other), new virulent viruses and infectious diseases, salinization where it doesn’t ‘belong’, plastic pollution in our oceans (where it really doesn’t belong), climate change and compromised food and job security for hundreds of millions of people, the combined impact of these challenges on human life are significant, to say the least.

While low-intensity seasonal or episodic fires are a natural part of the ecology in many regions of Australia such as the Kimberley (top left, photo A. Cross), intense, aseasonal or too-frequent fires can be devastating to ecosystems such as kwongan heathland (top right, photo A. Keesing) or seasonal peat wetlands (bottom; photo D. Edmonds).

The ecological and economic impacts of the environmental disaster known as climate change have resulted in thousands of jurisdictions in dozens of countries declaring a climate emergency, including many in Australia and Aotearoa New Zealand. Both countries are predicted to experience a hotter, drier climate in the coming years, a trend already showing itself through ominous impacts on forests and other ecosystems on land and at sea, including the oceans on Australia’s eastern coasts, where coral reefs and kelp forests are showing clear early signs of collapse. In both Australia and New Zealand, aseasonal or large-scale fires appear to be pushing some endangered species towards extinction and vital habitats and ecosystems to the brink. During the Australian summer of 2019-2020, unusually intense wildfires burnt an estimated 18.6 million hectares (46 million acres) across Australia and left ecosystems and communities reeling: the fires killed 34 and destroyed approximately 3,000 homes, and are estimated to have killed over a billion native animals.

Australia’s exceptional biodiversity includes many unique species, such as the Thorny Devil (Moloch horridus; Left), Emu (Dromaius novaehollandiae, Center), and Echidna (Tachyglossus aculeatus; Right). All photos Sophie Cross.

These fires and their aftermath have created a flashpoint where conflicting responses to climate change and its effects are emerging in sharp relief. Strong social divisions have long existed over expanding gas, oil, and coal mining projects in mainland Australia and Tasmania, all of which of course contribute massively to anthropogenic climate change. Debate and conflict over logging in the remaining natural forests has also intensified. The degradation of ecosystems can also cause significant public health impacts. Studies have linked high rates of depression and even suicides in farming communities to the stresses of drought and fire. The fragmentation and clearing of forests for timber and unsustainable agricultural practices has isolated and displaced Indigenous Peoples and communities, leading to conflict, loss of cultural identity, and damage to livelihoods, and has contributed to a rise in zoonotic (animal-transmitted) diseases such as the catastrophic and ongoing effects of Covid-19. Smoke from the recent Australian bushfires reduced air quality to dangerous levels in cities around Australia, potentially killing 12-times more people than the flames did, and the smoke plume travelled over 11,000 km across the Pacific Ocean to South America.

Time for Deep Change

In support of the upcoming UN Decade on Ecosystem Restoration (to run from 2021–2030, concurrently with a Decade on Ocean Science for Sustainable Development), two recent articles by Breed et al. and Aronson et al. bring new weight to the argument that ecological restoration is one of the most promising strategies we have to stop and reverse our current trajectory of environmental chaos. Indeed, Breed and colleagues suggest that the human health benefits of undertaking and engaging in ecological restoration might be so significant that restoration could be considered an economically and politically effective large-scale public health intervention. These benefits might be at the scale of the individual, resulting from direct participation in restoration activities (e.g., the act of working together on restoring an area can reduce anxiety and depression-related diseases). Or, they might be at the population and community levels, resulting from the indirect outcomes of ecological restoration (e.g., restored ecosystems and reintegrated landscapes provide cleaner water, and more health-promoting microbiomes, reducing a number of disease risks).

Restoration projects, such as the Arbor Day planting events of People, Cities & Nature, at Waiwhakareke Natural Heritage Park in Hamilton, New Zealand, can bring community together and may have significant public health benefits for participants. All photos C. Kirby.

Breed and colleagues proposed five key strategies to help us better understand the potential of ecological restoration as a public health initiative:

  1. Collaborations and conversations. Promoting greater collaboration among scientists of various disciplines, health professionals, restoration practitioners, and policymakers to better understand the links between ecological restoration and human health and wellbeing (including jobs and livelihoods).  
  2. Education and learning. Restorationists need to learn about human health, and health professionals must in turn learn about the real potential of ecological restoration as a public health intervention.
  3. Defining the causal links. Research is needed to determine the causal links between ecosystem restoration and health outcomes, to provide the empirical evidence required to understand and advise communities and decision makers.
  4. Monitoring restoration and health outcomes. We need better and standardized methodologies for the effective, cost-efficient monitoring and evaluation of the public health benefits from ecosystem restoration.
  5. Community ownership and stewardship. A global movement toward a restorative culture needs community involvement and engagement, and embracing of the importance of traditional ecological knowledge.

Putting these strategies into action at a scale required to meet the aspirations of the coming UN Decade means we must collaborate across continents and disciplines to identify and build links between ecological restoration and human health.

One such initiative is the Ecohealth Network (EHN), established in 2017 to bring together pioneering sites, hubs, and regional networks to work cohesively towards rapidly increasing the amount and effectiveness of ecological restoration throughout the world, and to accelerate understanding and awareness of its feasibility and benefits, especially for public health.

The first EHN regional network emerged from a workshop held in February 2020. The group calls itself the Four Islands EcoHealth Network, in reference to North Island and South Island, the two largest islands of Aotearoa New Zealand, plus Tasmania, and mainland Australia. It aims to explore how different sites and hubs with various climatic and cultural contexts can come together to share insights and pursue research into the physiological, psychological, and societal health benefits of ecological restoration. It also aims to advance the ecological and microbiological knowledge needed to achieve effective, durable restoration. The aspirations, aims and issues to be considered by the group were laid out in the Hobart Declaration, a charter document stemming from the workshop. Keith Bradby, the founder and CEO of Gondwana Link, agreed to be the first coordinator of the regional network.

The Four Islands EcoHealth Network also embodies a shared desire to foster support for long-overdue efforts in both countries that work in close collaboration with Indigenous Peoples and local communities to make radical changes in cultural, educational, and land care practices. A recent popular science article by Dr. Kiri Joy Wallace highlighted the significance of these aspirations to the public health sector, native ecosystems, and people of Aotearoa New Zealand. There are also many Australian contexts bringing insight and direction to the initiative. For example, Gondwana Link is working to restore ecological resilience to thousands of hectares of marginal farmland following long colonial histories of Neo-European style agricultural use and severe salinization in southwestern Australia; Gondwana Link is exemplary in its huge regional scope and sustained work for greater interaction and cooperation not only with local conservation groups, but also with Noongar and Ngadju Traditional Owners. This effort, based on a vision shared by all members of the EHN, is part of the essential process of “decolonizing” both conservation and ecological restoration.

Other members of the Four Islands EcoHealth Network tackle the restoration and assisted recovery of wilderness areas in north-eastern Tasmania following industrial tree cropping with Monterrey pine (Pinus radiata), undertaken with great success by the North East Bioregional Network; vast regional, multi-state initiatives such as the Great Eastern Ranges work to conserve and reconnect habitat at large scales; and science-led and community-focussed programs such as the UN-endorsed Healthy Urban Microbiome Initiative, which explores the human health benefits of biodiverse green space in urban areas via the microbiome and smaller local studies examining the mental health benefits of urban schoolchildren participating in restorative activities.

These experiences in the Four Islands context, and the insights and expertise of its founding members, are helping to anchor and inform efforts by the wider EcoHealth Network to link similarly ambitious initiatives in other regions and build a broad global network stretching across the globe.

Restoration can and must underpin every aspect of human society, as our health and welfare, and those of future generations, are dependent on the ecosystems of which we are part. If we are to achieve the aspirations of the coming UN Decade on Ecosystem Restoration, we need to work towards a culture of healing and renewal to replace the damaging models of colonialism, systemic injustice, unrestrained resource extraction, and ecological destruction. The accelerating climate catastrophe and the Covid-19 pandemic have profoundly impacted people’s lives in every nation, increasing awareness about the direct link between human health and the environment. We need to ensure this catalyzes a shift to a restorative culture globally, toward what we can only hope will one day be a world of truly united nations.

To learn more about the Ecohealth Network or the work of the members of the Four Islands Ecohealth Network, visit our website or read our recent papers in EcoHealth and Restoration Ecology.

Do we really need to plant a trillion trees? Tree islands are an ecologically and economically sound strategy to facilitate tropical forest recovery

Karen Holl (UC Santa Cruz) and Leighton Reid (Virginia Tech) describe lessons learned from a 15-year study of tropical forest restoration in southern Costa Rica. Their new paper is published in the Journal of Applied Ecology.

It seems that everybody from business people to politicians to even Youtubers is proposing that we should plant millions, billions, or even trillions of trees. They cite a host of reasons, such as storing carbon, conserving biodiversity, and providing income. These efforts should be done carefully and with a long-term commitment to ensure that the trees survive and to prevent unintended negative consequences, such as destroying native grasslands, reducing water supply in arid areas, or diverting attention from efforts to reduce greenhouse gas emissions.

Another important question is whether we really need to plant that many trees to restore forest. In a new paper in the Journal of Applied Ecology, we summarize some the lessons we have learned about a different approach.

Volunteer plants tree seedlings in one of our plantations in southern Costa Rica. Photo: Karen Holl

Over 15 years ago, we set up an experiment in southern Costa Rica to test whether planting small patches or “islands” of trees could speed up forest recovery for a lower cost than typical tree plantations. The idea is to plant small groups of trees that attract birds and bats, which disperse most tropical forest tree seeds. The tree canopy also shades out light-demanding grasses that can outcompete tree seedlings. As a result, over time these tree islands spread as they grow and facilitate the establishment of a lot more trees.

Compared to tree plantations, the tree island approach has two major benefits. First, it better simulates the patchiness of natural forest recovery. Second, it costs much less than planting rows and rows of trees.

Trade-offs in forest restoration strategies. Planting fewer trees leaves more to chance and can require more time, but tree plantations are more expensive and leave a bigger ecological footprint. Our study tests an intermediate option, and after 15 years it appears to provide a good balance. Figure modified from Corbin & Holl (2012).

In our experiment, we planted tree islands that covered about 20% of a 50 × 50 m plot of former cattle pasture. We compared that to plots where no trees were planted (natural recovery) and to the more intensive and more typical restoration strategy of planting trees in rows throughout the plot (plantation). We repeated this set-up at 15 sites in 2004-2006.

Over the past 15 years, we have monitored the recovery of vegetation, litterfall, nutrient cycling, epiphytes, birds, bats, arthropods, and more. Our data reveal a few key lessons about how to restore tropical forests more ecologically and economically.

First, our data show that planting tree islands is as effective as bigger tree plantations, despite cutting costs by around two-thirds. Compared to plantations, tree islands have similar recovery of nutrient cycling, tree seedling recruitment, and visitation by fruit-eating animals. Both tree islands and plantations speed up tropical forest recovery compared to letting the forest recover on its own. After 15 years, cover of trees and shrubs in the island planting plots has increased from 20% to over 90%.

Artist's depiction of three tropical forest restoration treatments: natural regeneration, tree islands, and plantation.
Drawing of our three treatments showing a few trees establishing in the natural regeneration plots, the tree island merging canopies merging in the island plots, and the rows of trees in the plantation. Artist: Michelle Pastor.

Second, we have found that larger tree islands are more effective than smaller islands in enhancing the establishment of fauna and flora, as larger tree islands attract more birds and shade out competitive grasses.

Third, while tree islands cost less than plantations, some landowners won’t use the tree island approach because the land looks “messier” than orderly tree plantations. Some people prefer to plant lots of trees that are valuable for timber or fruit, rather than having the diverse suite of species that are typical of a tropical forest. So, the tree island planting strategy will be more suitable in cases where the goal is to restore forest.

Natural recruitment of trees seedling in the understory of a canopy of planted trees.

Our results and those of others show that the tree island planting approach holds promise as a cost-effective forest restoration strategy in cases where there are seed sources nearby to colonize and animals to disperse them, and where the spread of tree islands is not likely to be slowed by fire or invasive species. But we need more long-term studies to judge whether tree islands will be effective in other tropical forest ecosystems and to test other questions, like how the particular tree species used affect forest recovery, or what is the best distance to leave between tree islands.

More broadly, our study shows that tropical forests can recover some species quickly but it will take many decades, or longer, for forests to fully recover. So, preserving existing rain forests is critical to conserve biodiversity and the services that intact forests provide to people.

Yes, carefully-planned tree planting can help accelerate tropical forest recovery. But, in many cases we don’t need to plant trees everywhere. Rather we should use restoration strategies that encourage trees to plant themselves.

To learn more about our research, read our new article in the Journal of Applied Ecology, visit our websites (Holl Lab, Reid Lab), or watch a 7-min. video below.

Karen Holl describes the tree planting restoration approach and our long-term experiment in southern Costa Rica.
Los investigadores principales describen el método de applied nucleation y nuestro experimento a largo plazo en el sur de Costa Rica.

A ten-year woodland restoration trajectory

Leighton Reid describes a long-term ecological research project at Shaw Nature Reserve (Franklin County, Missouri, USA). To learn more, read the new research paper (email the author for a pdf copy – jlreid@vt.edu) or tune in for a webinar from the Natural Areas Association on April 21 (register here).

In 2000, the Dana Brown Woods were dark and dense. Brown oak leaves and juniper needles covered the sparsely vegetated ground, and invasive honeysuckle was creeping in around the edges. Biologically, the woodland was getting dormant.

In contrast, the woods today are lit by sunlight everywhere except the lowest-lying streambanks, and the ground is hardly visible beneath a green layer of diverse, ground-level foliage. These changes were most likely caused by two actions: burning the woods, and cutting out invasive trees and shrubs.

Many practitioners have seen woodlands recover to some extent when they are burned, but few have documented the recovery as thoroughly and over so long a period of time as Nels Holmberg and James Trager.

IMG_0101-001

Nels Holmberg (left) discussing the finer points of Rubus identification with Quinn Long in the Dana Brown Woods.

Nels is an ecologist and sheep farmer in Washington, Missouri. He has inventoried the plants at several state parks and natural areas. In 2000, Nels teamed up with Shaw Nature Reserve’s resident natural historian, James Trager, and together they designed a study to describe how ecological restoration was changing the woodland flora at the reserve. They picked the Dana Brown Woods as their study area.

In a nutshell, Nels and James chose 30 random points on a map. They divided the points evenly across three ecological communities. They placed 10 points in mesic woodlands – the gently sloping parts of the property where white oak and shagbark hickory were most prevalent. Ten points were in areas dominated by eastern red cedar – mostly thin-soiled ridgetops that faced the south, and ten points were in forest – the lower, thicker-soiled toe slopes where northern red oak and Shumard oak were dominant in the canopy with paw paws and spicebush down below.

Fig_RevisedHabitats_HiRes_v2.3

Three ecological communities in the Dana Brown Woods: (A) red cedar dominated areas which, after removing red cedar, looked more like dolomite glades in some parts; (B) mesic woodlands with lots of oak and hickory in the canopy; and (C) forest – which had a much darker understory.

At each point, Nels hammered in a t-post, then walked 50 m in the steepest direction and hammered in another t-post. This was his transect. Every year for more than a decade (2000-2012), Nels walked the transects and recorded every stem of every species that was inside of 10 0.5-m2 study plots. Actually, he did this twice per year – once in the spring to capture the ephemeral plants, and once in early summer. Over the course of the study he spent more than 200 days in the field.

Canopy Cover

Dana Brown Woods before (left) and after (right) red cedar removal, with Nels’s 30 transects. The horizontal axis of the image is about 0.9 km. Imagery is from Google Earth.

During this time the stewards at Shaw Nature Reserve were busy restoring the woods. From 2001-2012, they burned the woods five times. This amounted to about one fire every three years. In 2005-2006, they brought in a logging crew to remove all of the eastern red cedars.

Maker:L,Date:2017-8-24,Ver:5,Lens:Kan03,Act:Kan02,E-ve

James Trager lights a fire in a woodland at Shaw Nature Reserve.

BigJuniperStump_20151104

One of several thousand red cedar stumps from trees that were harvested from the Dana Brown Woods in 2005-2006.

Plot R8

One of Nels’s sampling quadrats in the Dana Brown Woods. Photo: Nels Holmberg.

I met Nels and James in 2014. I had just joined Missouri Botanical Garden’s Center for Conservation and Sustainable Development as a postdoc, and I was looking for a local research project. I heard that Nels Holmberg had a giant dataset about woodland restoration, so I called him and asked if I could look at it. Nels said “Sure!”. I imagined he would send me an Excel file. Instead he brought in a giant cardboard box full of yellow legal pads where he had recorded his data.

OLYMPUS DIGITAL CAMERA

One of hundreds of datasheets where Nels recorded his detailed observations.

It took a long time to digitize all of the data. There were more than 50,000 data points. But once we had it all together, this is what we learned:

After eleven years of restoration, the number of native plant species in Dana Brown Woods increased by 35%, from 155 species in 2001 to 210 species in 2012. This increase was linear. That is, the number of native species was still increasing at the end of the study. If we repeated the study today, we expect the number of native species would be even greater than in 2012.

The number of native species increased at different speeds and to different degrees in different ecological communities. In the lower and wetter forest areas, the numbers didn’t really shift very much. They jumped around but not in one direction. In the woodland areas, the number of native species increased by about 23% in the first three years and then leveled out. But in the higher and drier areas where red cedars had been dominant, the number of plants increased linearly by 36%.

Native Species Richness

Changes in the number of native plant species recorded over time in the Dana Brown Woods. On the left are overall changes for the whole management unit. On the right are changes for different ecological communities within the management unit. The management interventions are shown in gray.

The plant species that benefited from the restoration were mostly forbs and grasses. A couple of the biggest “winners” were black snakeroot (Sanicula odorata) and nodding fescue (Festuca subverticillata). There were also some “losers”: Virginia creeper (Parthenocissus quenquefolia) and spring beauty (Claytonia virginica) both declined over time. Relatively few of the species that became more common were “conservative” – i.e., dependent on intact habitat. Mostly they were more widespread and tolerant species.

IMG_0049

Co-author Olivia Hajek demonstrates a hog peanut (Amphicarpaea bracteata) – a good representative of the type of species that benefited most from the restoration. Hog peanut is an herbaceous legume that is common in many woodlands, including disturbed ones.

Our study did not include a control treatment, but counterfactuals exist at Shaw Nature Reserve (although they are becoming fewer and fewer with the excellent stewardship of Mike Saxton and many others). There are still thick patches of eastern red cedar covering remnant glades on parts of the property. Woodlands that have not been regularly burned are now filled with bush honeysuckle (Lonicera maackii), wintercreeper (Euonymus fortunei), and other invaders. And low-lying forest that has not been restored is very dark with fire-intolerant sugar maple (Acer saccharum) casting much of the shade. If we had included a control treatment in our experiment, these are probably the trends we would have found – definitely not a spontaneous resurgence of diverse native plants.

IMG_0099

Fragrant sumac (Rhus aromatica) was present at the outset of restoration and remained relatively stable.

Why does this work matter? The biggest value of this study is that it shows a relatively long-term restoration trajectory, and it does so in fine botanical detail. Many managers and scientists already have data to show that fire and tree thinning increase woodland plant diversity. This study adds another dimension. It shows how quickly plant diversity recovered. It also shows how the speed and shape of the recovery varied across the landscape. We hope that other scientists and practitioners will compare the recovery trajectories in the Dana Brown Woods to their own natural areas. To facilitate that, we have made all of the underlying data freely available online.

IMG_0029

Buffalo clover (Trifolium reflexum) is a conservative species that is present in Dana Brown Woods but was not detected in any of the survey plots.

One of the next steps for this research is to figure out how and when to re-introduce some more conservative plants. Although the Dana Brown Woods became much more diverse as it was being restored, most of the plants were early successional or generalist species. We found very few habitat specialists that cannot tolerate disturbance, which suggested to us that some of these species may have been lost from the site at some time in the past. To learn how conservative plants might be re-introduced, we have started a new experiment testing the effects of soil microbes, competition, and time since the start of restoration on the success of introduced seedlings from seven conservative plant species. In the next year or two, we hope to have new information and recommendations for restorationists looking to add more specialized biodiversity to their woodlands.

WP_20150502_004

Freemont’s leather flower (Clematis fremontii) is a restricted species occurring on dolomite glades in southeastern Missouri. Although it is present at Shaw Nature Reserve less than one kilometer from Dana Brown Woods, it has not colonized the restored glade habitats there. This photo is from Valley View Glade near Hillsboro, Missouri.

To learn more about this research, you can read the original research paper in Natural Areas Journal. Email me for a pdf copy (jlreid@vt.edu). You can also tune in on April 21 for a webinar on this work. Register here.

New book: Primer of Ecological Restoration

Karen Holl is a professor in the Environmental Studies Department at the University of California Santa Cruz. She describes her new book, which provides an introduction to the field of ecological restoration. Primer of Ecological Restoration is available from Island Press (Use promo code PRIMER to get 20% off).

My husband teases me that it took me over 25 years to write my new book, Primer of Ecological Restoration. Indeed, I was working on a restoration ecology textbook the summer of 1994 when we met. But I decided that writing a textbook during my post-doc wasn’t a smart career move if I wanted to succeed in becoming a tenured professor. So, I put the book project on hold. I periodically revisited the idea over the next two decades as I developed my research programs on restoring tropical forests in Latin America and grasslands and riparian forests in California; taught a yearly undergraduate restoration ecology course; and collaborated with many restoration practitioners. A few years ago, when Island Press asked me if I would write a succinct, “primer” for the field of ecological restoration, I decided the time was finally right. So, my husband is correct that I have been working on this book in some form or another for many years, and I am thrilled that it is finally available from Island Press and most major book sellers.

Book Cover

Primer of Ecological Restoration (March 2020) introduces restoration in short chapters written to be read by students, land managers, and anyone interested in the topic.

The science and practice of ecological restoration have grown exponentially over the past few decades, as we aim to compensate for the negative impacts humans have had on the ecosystems that we and millions of other species depend on. With the growth of ecological restoration has come a plethora of resources: thousands of articles in the peer-reviewed and management literature, countless websites describing individual projects, and many books focused on restoring specific ecosystems.

My goal with this book is to provide a broad but succinct introduction and guide to the rapidly growing field of ecological restoration for a few audiences.

  1. I and a few other instructors, including blog editor Leighton Reid, are already using my book as an introductory text for undergraduate courses in Ecological Restoration and Restoration Ecology. Instructors can complement the book with in depth readings on specific topics and case studies tailored to the focus of the course.
  2. My primer could be used as one of a few texts in courses on Conservation Biology and Resource Management where ecological restoration is not the only topic covered.
  3. I hope this book will be of interest to natural resource managers and others who want a short introduction to ecological restoration.

To that end, I have aimed to keep jargon to a minimum and define terms in both the text and the glossary.

Fig5.4color

Approaches to increasing habitat connectivity through restoration. From Primer of Ecological Restoration. Credit: Alicia Calle.

Restoring ecosystems requires an interdisciplinary background. It is essential to understand the ecology and natural history of the ecosystem being restored and know appropriate restoration methods. But, as any practitioner knows, successful projects require familiarity with many other topics, including managing stakeholder involvement and public outreach; experience with planning, goal setting, and monitoring; and knowledge of relevant laws, permitting processes, and funding sources. My book could not possibly discuss all these topics in detail while achieving the goal of brevity, so I provide an overview of key points and illustrate them with brief examples. I co-wrote several online case studies that provide detailed information and integrate various themes illustrated by the project.

The saying that “a picture is worth a thousand words” couldn’t be truer for ecological restoration. There is no substitute for seeing before and after photos of projects and visiting restoration sites in person. Nonetheless, I used selected diagrams and tables in the book and incorporated color photos in the online case studies, to make the book cheaper and more accessible to a broad audience. The book website has links to many restoration project websites, photos, and videos available on the internet, which I will continue to update over time to reflect new approaches in this rapidly changing field.

Figure6-6A

Key habitat features in a restored meandering river. From Primer of Ecological Restoration. Credit: Michelle Pastor.

This book is not intended as a thorough guide of how to restore specific ecosystem types, so readers are likely to want more in depth resources on specific topics. To this end, I have provided short reading lists at the end of each chapter. On the website, I provide questions for reflection and discussion that ask readers to apply the ideas presented in the book to a restoration project of their choice. The website also has examples of restoration project design plans that restoration practitioners have kindly shared, and I welcome suggestions from readers for additional resources to include.

I hope you find the book interesting and stimulating, and look forward to your feedback. You can review a detailed table of contents here. Finally, a quick tip that you can get a 20% discount on the book if you purchase the book at the Island Press website and use the promo code PRIMER.

 

Global pledges to restore forests face challenges, and need increased support

Matthew Fagan is an assistant professor in Geography and Environmental Systems at University of Maryland Baltimore County. Here he describes the challenges confronting countries as they attempt large-scale forest restoration, and why many countries will need help to fulfill their goals. For more information, read his new, open-access paper in Conservation Letters.

Degraded and deforested landscapes are widespread, and tropical forests are being lost at a rate of 15.8 million hectares a year. But there is good news—temperate forest area is increasing, and more and more countries are voluntarily pledging to restore vast tracts of degraded land. Restoring forests benefits biodiversity and society, and can combat global warming as well, as growing trees lock away carbon dioxide.

International interest in restoring trees to landscapes emerged out of policy discussions last decade, and resulted in the 2011 Bonn Challenge and the creation of voluntary national restoration targets by many countries. The Bonn Challenge seeks to bring 150 million hectares into restoration by 2020, and 350 million hectarees by 2030 (that’s roughly 700 million American football fields, 350 million rugby fields, 500 million FIFA football fields, or an area a bit larger than India).

Current Bonn Challenge pledges total some 172 million hectares. That’s a massive international commitment, and when you add in internal commitments by countries, the potential restoration area swells to 318 million hectares.

All that area voluntarily committed to restoration got my co-authors and I excited, but also skeptical—were countries really going to follow through on their commitments?

Fagan_RainforestBlowdown

A rain forest blow-down in northeastern Costa Rica, with a storm-downed tree cut to clear a path. Silviculture restoration promotes the recovery of disturbed forests like this one. Photo credit: Matthew Fagan.

To try to answer that question at this early stage, myself, Leighton Reid (Virginia Tech), Maggie Holland (UMBC), Justin Drew (UMBC), and Rakan Zahawi (University of Hawaiʻi at Mānoa) asked three related questions in a recent paper in Conservation Letters.

  1. Is the amount of land a country pledged to restore related to their past record of restoring forested landscapes and implementing sustainable development?
  2. For the small group of countries that have publicly reported their progress on commitments, is the amount of restoration they completed predictable by their development level or other risk factors, like deforestation?
  3. Which countries will likely face the greatest challenges to meet their commitments and maintain restored land into the future?

We then set to gathering published information on country commitments and progress, and recent national rates of forest loss, agricultural expansion, and forest recovery.

Fagan_NaturalRegeneration

Recent natural regeneration in northeastern Costa Rica of varying ages. Photo credit: Matthew Fagan.

All of these programs seek to reforest landscapes in ways that benefit both nature and people, including options like natural regeneration (letting natural forests recover and expand), silviculture (interventions to restore standing forests, like preventing forest fires and promoting recovery from selective logging), tree plantations (often tree monocultures to produce timber and pulp on degraded lands), and agroforestry (planting trees on and around farmland to shade crops or protect streams and fields). These options are not all equal in their benefits for biodiversity, carbon, and society, but a diverse menu of options allows countries to consider committing to at least some form of restoration over large areas.

Fagan_VochysiaPlantation2

A tree plantation in northeastern Costa Rica funded by the national payments for environmental services program. It is a monoculture of a single native species, Vochysia guatemalensis, grown for timber. Photo credit: Matthew Fagan.

In a nutshell, what we found was both discouraging and encouraging.

First, after adjusting for the size of a country and how much restoration they had done previously, we found that less-developed countries committed more land for restoration. This might be for positive reasons; for example, they may be taking proactive action against the greater risk they face from climate change. Or it might be because they underestimated how challenging it would be to achieve a large pledge.

Fagan_Silvopasture

Silvopastoral restoration, a type of agroforestry, in northeastern Costa Rica. The understory is a cattle pasture, while the overstory is plantation of a native tree species, Dipteryx panamensis. Photo credit: Matthew Fagan.

Second, for twelve early-reporting countries, restoration progress was predictable based on a risk index. Countries with higher risk (risk factors included deforestation rates and progress on sustainable development goals, among others) had less restoration progress.

Third, countries made massive individual commitments that will be hard to achieve without wholesale transformation of their food systems. One third of countries committed >10% of their land area (with a maximum of 81%, in Rwanda). A quarter either committed more area than they had in agriculture, or committed more area than they had in forest. And one quarter of countries had more forest loss and agricultural conversion in 2000–2015 than their restoration commitment for 2015–2030.

Fagan_ShadeCoffee

Coffee plantation under tree cover, a type of agroforestry, in central Costa Rica. The understory is a monoculture of coffee shrubs, while the overstory is scattered planted trees. The partial cover helps the shade-loving coffee plants stay healthy, but many coffee farmers are moving away from this traditional farming approach. Photo credit: Matthew Fagan.

As noted in our paper, “If voluntary commitments like the Bonn Challenge fail to precipitate meaningful restoration across large areas, the UN’s vision of a sustainable future will become less attainable.” But what this study found is not countries that have failed on their restoration pledges. We are still in the first days of the UN Decade of Ecosystem Restoration. What we have identified is countries that will need help to restore their lands.

We believe it is time for the international community to step up and aid all countries in achieving their restoration goals. To quote Thoreau, “If you have built castles in the air, your work need not be lost; that is where they should be. Now put the foundations under them.”

Fagan_Rainbow

A regrowing forest in central Costa Rica, showing the promise of restoration. Photo credit: Matthew Fagan.

A foray in the Mojave Desert

Thibaud Aronson describes the botany, ecology, and degradation of southern California’s unique desert woodlands.

There are four deserts in North America – the Great Basin, Chihuahuan, Sonoran, and the Mojave. Both the Great Basin and the Chihuahuan deserts can have bitterly cold winters, and as a result their vegetation is quite stunted compared to the other two, with precious few trees. A few years ago, my father and I spent a fair amount of time in the Sonoran desert, both in Arizona and in Baja California, documenting its remarkable trees.

To fill an important gap in our survey of desert trees of the world, I recently visited the Mojave desert, home to one of the most iconic desert trees on the continent. Indeed, just about every time one mentions desert trees, at least in the US, the most common response is: “Oh, like Joshua trees?” Like Joshua trees, indeed.

1- P1040365

The iconic Joshua tree (Yucca brevifolia) in the national park that bears its name in southern California’s Mojave desert.

As is typical in California, very different landscapes succeed each other in a relatively small area. So, over a week and surprisingly small distances, I traveled the region to get a sense of its rich tapestry of habitats  (see my itinerary).

Heading east from LAX Airport, I drove up a winding road into the San Gabriel Mountains. By the time I reached 2000 meters (6500 feet), I was completely surrounded by tall, dense forests comprising six or seven intermingled conifer species, and a number of ski resorts, deserted in the summer season. At my campsite that night, the temperature dropped to just a hair above freezing, quite a contrast from the stifling August heat I’d experienced that very morning!

The next day, I followed the spine of the mountains through the San Gabriels and on to the San Bernardinos. Driving along the glittering blue waters of Big Bear Lake, I went past “Starvation Flats Road”, a warning of what lay ahead. And indeed, I soon reached the eastern slopes, which gave me a striking view of the Mojave desert below – stark yellow plains that disappeared in the haze. Making my way down, the conifers began to thin out, and soon the first Joshua trees began to appear, some of them nearly as tall as the oaks they grew with.

2- 6Z1A2376

On the eastern foothills of the San Bernardino mountains, Joshua trees grow together with Valley oaks (Quercus lobata) and California Black oaks (Q. kelloggii).

Turning back to look at where I had come from, I could see Old Greyback, the tallest summit in southern California. Then I headed southeast, hugging the base of the mountains, to the famous town of Palm Springs. Originally the town was named for the freshwater springs that flow down from the mountains and the California Palms (Washingtonia filifera) that grow along the canyons. Today the palms line every street in town, towering above the low buildings.

3- 6Z1A2818

The skinny, carefully trimmed palms that define the look of Palm Springs are in fact unnatural, as wild fan palms develop thick skirts from their dead leaves that can extend almost all the way down to the ground. See below.

The landscape to the east of town is desolate, highlighting how precious and unusual the springs are. Creosote shrubs, their leaves a characteristic greyish yellowish, grow on the dusty flats as the incessant wind spins the thousands of turbines of the San Gorgonio Pass wind farm (the third largest in the state). Suddenly, a green ribbon appeared in the distance, and as I got closer, it resolved itself into a copse of large cottonwood trees, towering over an incredibly thick mesquite thicket. This is Big Morongo Canyon, the largest freshwater spring in the region.

4- 6Z1A2534_stitch

The thick canopy of cottonwoods (Populus fremontii) at Big Morongo canyon.

As soon as I stepped under the trees, it was clear that I had entered an oasis of life: orioles, goldfinches and hummingbirds flitted in the undergrowth, while jays pestered a great horned owl that they had found perched in a cottonwood. Cottontail rabbits hopped on the path ahead of me, and a coachwhip (Masticophis flagellum) rattled its tail at me, this tiny, harmless snake attempting (as many other local snakes do) to look like a rattlesnake to scare off potential predators.

5- 6Z1A2682

A female Anna’s hummingbird (Calypte anna) and some bees drinking at Big Morongo.

Before it got too hot, I continued on my way farther east, until I reached Yucca Valley, and from there Joshua Tree National Park. It is a surreal experience, as they appear almost out of nowhere, the phantasmagorical silhouettes of these giant tree Yuccas stretching to the horizon, the unique bluish grey tinge of their leaves giving a peculiar appearance to the air itself. It is a landscape quite unlike any I had ever seen. Though it is hard to understand how the first pilgrims decided that one of these trees was the prophet Joshua, pointing them in the direction of the promised land, as each tree seems to point a different way!

6 -6Z1A3045

Right on the edge of the national park, a Greater Roadrunner (Geococcyx californianus) looks for its next prey perched in a Joshua Tree.

While the northern parts of the Mojave are low-lying, making up the famously inhospitable Death Valley, Joshua Tree National Park sits at the southern edge of the desert, on a plateau about 1200 meters (4000 ft) above sea level. The cooler temperatures at that altitude are what allow the Yuccas to thrive, in truly remarkable numbers.

7 -6Z1A3761-2

A typical scene from the northern section of the park. I couldn’t find any data on this, but there must be tens, if not hundreds of thousands of Joshua Trees in the park.

While Joshua trees are the most distinctive – and seemingly the hardiest, growing even in the most exposed flats – they are not the only trees of the park. Many sandy desert washes cross the plateau, and along each of them grow various dicot trees. Most noticeable among these is Chilopsis linearis, in the Bignonia family. In the vernacular, it is known as ‘Desert willow’ because of its unusually long, narrow leaves and the fact that it grows in riparian habitats. Another tree found in the Mojave is the Papilionoid legume Psorothamnus spinosus, known as ‘Smoke tree’, as its pale grey leaves look like a cloudy puff of ashes, brightened in  summer when the trees are covered with gorgeous indigo-tinted, pea-like, flowers.

8- 6Z1A4514-2

Smoke trees in the aptly-named Smoke Tree Wash, inside the Joshua Tree National Park.

Finally, there are two species of the legume tree Palo Verde (Parkinsonia), one of which I found providing shelter for a desert bighorn one evening near my campsite.

9 - P1040572

A young desert bighorn sheep (Ovis canadensis nelsoni). Bighorn populations have recovered quite well in recent decades, though they are still facing various threats in the California deserts. There are fewer than 300 found in Joshua Tree National Park (ca. 800,000 acres, or 3,200 km² in size).

Furthermore, the park is known for its elaborate formations of basaltic rock, which add to the surreal beauty of the landscape, and attract rock-climbers from all over the world. These rock piles, with the shelter and extra moisture that they provide, also allow oaks, pinyon pines, and junipers (all trees that typically grow on the higher mountain slopes) to survive down on the plateau as well.

10 - 6Z1A3640-2

At Hidden Valley, in the central section of the park, large pinyon pines (Pinus monophylla) grow among the basalt rock piles.

There are also several fan palm oases in the park, from Fortynine Palms, standing on its own amid the bare rocky slopes, reminding me of the mountains of northern Oman, to the glorious Cottonwood Springs, where massive cottonwoods barely top over the enormous palm trees, who formed a dense cluster sheltering a family of barn owls.

The saddest fan palm oasis is undoubtedly Mara, also known as Twentynine Palms. It is said that the Serrano Indians who used to live in the area planted one palm tree for each son that was born to the tribe after they first settled there. Last year, a criminal fire swept through the area, killing several of the palm trees. Some blackened trunks still stand, while several others had to be completely cut down. All in all, it is a sadly apt metaphor for what has befallen these first nations of indigenous people who called the area home for centuries prior to the arrival of Europeans.

11- 6Z1A4292_stitch

12 - 6Z1A3312

Compare the glorious Cottonwood spring, protected as it is in a remote part of the national park, with the sad oasis of Mara, still showing the scars from last year’s fire that was set by an arsonist.

From there, I drove south through the park, and the landscape began to change markedly, as this is the where the Mojave gives way to the Sonoran desert. It got warmer and drier as the elevation decreased. The Joshua trees disappeared, replaced by ocotillos and in some areas, fields of teddybear cholla cacti (Cylindropuntia bigelovii). Passing through spectacular layers of exposed rock, I reached the Bajada, a grassy savanna with large ironwood trees (Olneya tesota, also a tree legume) a scene more akin to an African savanna than the landscapes I had left behind that same morning! This was quite striking as we had found ironwood trees to be much scarcer in Baja California!

From there, it was only a short way to the final stop on my trip: the Salton Sea. Lying about 70 meters below sea level, this is actually a depression, which was periodically filled by exceptional flooding on the Colorado River. The last time this happened was in 1905. Since it has no outlet, the lake progressively becomes more saline and eventually evaporates, until the Colorado floods its banks and fills it again.

Furthermore, because of repeated Colorado River floods, the surrounding soils are very fertile, despite the extremely dry climate. As a result, in the early 20th century, at the height of the hubris that characterized the development of the American Southwest, massive irrigation projects were put in place in the Coachella and Imperial valleys, at the northern and southern ends of the Salton Sea, respectively. The latter – formerly called Valley of Death, was rebranded as Imperial Valley – in a remarkable feat of marketing well described by Fred Pierce in When the Rivers Run Dry (2006). Today, the landscape as seen from the sky is surreal: the deep blue waters contrasting with the yellow of the surrounding desert, while the valleys at both ends are an incongruous green. The perfectly rectangular fields stretch all the way to the Mexican border, for a combined irrigated area equal to nearly three times that of the Salton Sea itself! These fields produce a large portion of the state’s lettuce, broccoli, carrots, and especially alfalfa, to feed California’s behemoth dairy industry. The sight of the hundreds of sprinklers going full tilt in the midday heat, to water alfalfa that could be grown in the East for a fraction of the cost, was rather off-putting, to say the least. (For a comprehensive and depressing history of water usage in the American West, read Cadillac Desert (1986), by Mark Reisner).

13 - P1040526

Irrigated vineyards in the southern end of the Coachella Valley. Note the extremely arid ranges in the distance, which stretch between Joshua Tree National Park and the Salton Sea.

As is by now well known, the Colorado has been well and truly “tamed”, its once wild run dammed in fifteen places, and every ounce of its water used to irrigate the thirsty cities and fields of the West, so that hardly a drop reaches its once mighty delta. In other words, the Salton Sea may soon be gone for good. And what else can we look forward to?

In a nutshell, the whole area is a mess. For a century, agricultural runoff has ended up in the Salton Sea itself and now, as the Sea is shrinking, more and more of its bed is being exposed and sediments heavily contaminated with salt and pesticides are being picked up by the winds. This is a massive public health issue. Not to mention the ecological disaster as the waters become too saline to support the fish that dwell in it, depriving the millions of birds that pass through the area of some of the only food available on that portion of the migration flyway. Furthermore, the well-publicized water shortages and catastrophic wildfires of California get worse with every passing year.

Obviously, agriculture in southern California will continue, but in what fashion? According to the California Department of Agriculture, more than half of the irrigated cropland in the state is badly affected by salinization. Surely this should be a wake-up call to explore alternative futures. For one thing, as Richard Felger, doyen of US-based Sonoran desert botanists and explorers, puts it, we need to learn to “Fit the crop to the land, not the land to the crop.”

Even though desert organisms are tremendously well-adapted to the harsh conditions they face on a daily basis, even they can only take so much. According to a recent study, rising temperatures are rapidly making the national park unsuitable for Joshua Trees themselves. In the best-case scenario, major efforts to reduce greenhouse gas emissions could save around 20% of suitable habitat for Joshua trees within the park after the year 2070. In the worst case, with no reduction in carbon emissions, 50 years from now,  the Joshua Tree National park will retain a mere 0.02 percent of its Joshua tree habitat.

The first white explorers who saw the Western deserts of North America thought them so hostile that they could never support settlement, disregarding the Native Americans and the wealth of fauna and flora who had long been living in the desert, in a very delicate balance. But in the frenzy of the twentieth century, through truly prodigious amounts of effort, descendants of the European colonists radically reshaped these landscapes to suit their needs with very little understanding of the long-term consequences of their actions. The entire enterprise is clearly and dangerously unsustainable, as water reserves that accumulated over hundreds of thousands of years were drained in just a few decades.

We often hear about the fight against desertification, which is conflated with some sort of fight against advancing deserts. But it is important to remember that deserts, while harsh, can still be beautiful and full of vibrant and unique life. Joshua Tree National Park, the Mojave National Preserve, and a few other protected areas give us a glimpse into what once was. But they are mere handkerchiefs. If the region is to have a chance at a sustainable future, we need new paradigms, new laws based on a much better understanding of how life can balance itself in arid lands. Based on that understanding, it is imperative that we move away from the pattern of careless exploitation and transformation, stretching farther and farther away from what these deserts once were. Instead, it is past time to commit to ecological restoration and allied activities for the Mojave and indeed all degraded and mis-used deserts and semi-deserts, especially as climate chaos unfolds.