native species

How non-native tree species affect biodiversity

Non-native forest tree species can reduce native species diversity if they are planted in uniform stands, finds an international review study.

Non-native forest tree species can reduce native species diversity if they are planted in uniform stands. In contrast, the effects of introduced species on soil properties are small. This was found by an international review study with the participation of the Swiss Federal Institute for Forest, Snow and Landscape Research WSL.

Curse or blessing? Opinions are divided on non-native tree species. In addition to native species, many foresters also plant non-native species that can withstand the increasing summer drought. In various parts of Europe, the latter are already important suppliers of timber. However, conservationists fear ecological damage, for example if native species are displaced or tree pathogens and insect pests are introduced.

In Switzerland, Douglas fir is partly used for afforestation. However, large pure stands, such as those found in Germany, are prohibited there. Photo by Thomas Reich

Now a team of European researchers, led by Thomas Wohlgemuth of WSL, has looked at the state of knowledge on the ecological consequences of alien tree species in Europe. They analysed the results of 103 studies on seven such species. All of these studies had investigated how stands dominated by non-native tree species affected biodiversity or soil condition under the trees compared to stands of native tree species. The organisms studied included plants, mosses, microorganisms and insects from the forest floor to the treetops.

Of the seven alien species studied, only the Douglas fir is currently planted in larger numbers in the Swiss forests. While foresters used to value its fast, straight growth and its versatile wood, today they appreciate its higher drought tolerance compared to spruce. Other species are problematic because they can spread uncontrollably. The North American Robinia, for example, is invasive and can displace native species. It was already introduced in Europe 400 years ago and used in Switzerland, among other things, to stabilise soils.

Robinia can spread rapidly and form stands as here in Valais. Photo by Thomas Reich

Negative effects on biodiversity predominate

Across the 103 studies, the consequences of non-native species for biodiversity were negative. Comparisons from 20 studies show, for example, that on average fewer insect species live on and in Douglas fir than in spruce or beech stands. Robinia also reduces the diversity of insects, eucalyptus that of birds. This is hardly surprising, says Wohlgemuth, head of the WSL Forest Dynamics Research Unit. Because: “These results apply to comparisons between pure stands.” In continuous, uniform plantations, many alien species clearly have worse impacts than native species.

Proportion of cases with increasing (green), decreasing (red) or non-significant (grey) effects of tree species non-native to Europe on diversity attributes (abundance, species richness or diversity) of different taxonomic groups in comparison to native vegetation. Numbers of cases are shown next to the NNTs names, below the diversity attributes and above the bars.

But alien species do not only have negative impacts. Most of them do not affect soil properties. The easily degradable needles of Douglas firs can even make more nutrients available than the poorly degradable spruce needles. “When it comes only to soil properties, the Douglas fir has no negative impact,” Wohlgemuth says. In general, an equal number of studies found positive and negative effects of the seven non-native species on the soil.

Douglas firs are attractive for forestry because of their fast growth, good wood properties and – in regard to climate change – their drought resistance. Photo by Thomas Reich

Furthermore, it makes a difference whether the alien species are more closely or more distantly related to European tree species. “Tree species without closer relatives, such as eucalyptus and acacia from Australia, reduce species diversity more strongly across all studies than closely related species, such as Douglas fir and wild black cherry from North America,” adds Martin Gossner, head of the WSL Forest Entomology Group and second author of the study.

A Douglas fir. Photo by Neptuul under a CC BY-SA 4.0 license

It all depends on the management

Management has a significant influence on whether Douglas fir or other tree species are good or bad for a forest overall. Uniform and dense Douglas fir stands are unsuitable habitats for many organisms. However, the same is true for spruces, which have been planted extensively for timber production in lowland areas of Central Europe over the last 100 years. On the other hand, Douglas firs in stands of native forest trees, individually or in small groups, would hardly disturb the ecosystem, Wohlgemuth says: “We conclude that the impact on native biodiversity is low with mixed-in Douglas firs.”

Should foresters plant non-native tree species or not? Despite certain negative aspects, Wohlgemuth does not recommend total renunciation. “Particularly in the case of Douglas fir, the facts show that moderate admixture in stands has little impact on native biodiversity, while at the same time preserving ecosystem services such as the production of construction timber. This is especially true when other, less drought-resistant conifers are increasingly lacking with regard to unchecked climate change.”

Research article:

Wohlgemuth T, Gossner MM, Campagnaro T, Marchante H, van Loo M, Vacchiano G, Castro-Díez P, Dobrowolska D, Gazda A, Keren S, Keserű Z, Koprowski M, La Porta N, Marozas V, Nygaard PH, Podrázský V, Puchałka R, Reisman-Berman O, Straigytė L, Ylioja T, Pötzelsberger E, Silva JS (2022) Impact of non-native tree species in Europe on soil properties and biodiversity: a review. NeoBiota 78: 45-69. https://doi.org/10.3897/neobiota.78.87022

Web news piece originally published by the Swiss Federal Institute for Forest, Snow and Landscape Research WSL. Republished with permission.

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Living room conservation: Gaming & virtual reality for insect and ecosystem conservation

Gaming and virtual reality could bridge the gap between urban societies and nature, thereby paving the way to insect conservation by the means of education and participation. This is what an interdisciplinary team at Florida International University strive to achieve by developing a virtual reality game (desktop version also available) dedicated to insect and plant species. Focused on imperiled butterflies, their innovative idea: Butterfly World 1.0, is described in the open-access journal Rethinking Ecology.

Participant playing the virtual reality version of Butterfly World 1.0.
Photo by Jaeson Clayborn.

Players explore and search for butterflies using knowledge gained through gameplay

Gaming and virtual reality (VR) could bridge the gap between urban societies and nature, thereby paving the way to insect conservation by the means of education, curiosity and life-like participation.

This is what Florida International University‘s team of computer scientist Alban Delamarre and biologist Dr Jaeson Clayborn strive to achieve by developing a VR game (desktop version also available) dedicated to insect and plant species. Focused on imperiled butterflies, their innovative idea: Butterfly World 1.0, is described in the open-access journal Rethinking Ecology.

When playing, information about each butterfly species is accessed on the player’s game tablet. Image by
Alban Delamarre and Dr Jaeson Clayborn.

Butterfly World 1.0 is an adventure game designed to engage its users in simulated exploration and education. Set in the subtropical dry forest of the Florida Keys (an archipelago situated off the southern coast of Florida, USA), Butterfly World draws the players into an immersive virtual environment where they learn about relationships between butterflies, plants, and invasive species. While exploring the set, they interact with and learn about the federally endangered Schaus’ swallowtail butterfly, the invasive graceful twig ant, native and exotic plants, and several other butterflies inhabiting the dry forest ecosystem. Other nature-related VR experiences, including conservation awareness and educational programs, rely on passive observations with minimal direct interactions between participants and the virtual environment.

According to the authors, virtual reality and serious gaming are “the new frontiers in environmental education” and “present a unique opportunity to interact with and learn about different species and ecosystems”.

In the real world, Spanish needles (Bidens alba) is considered a weed in South Florida. However, it is an excellent nectar source for butterflies.
Photo by Alban Delamarre.

The major advantage is that this type of interactive, computer-generated experience allows for people to observe phenomena otherwise impossible or difficult to witness, such as forest succession over long periods of time, rare butterflies in tropical dry forests, or the effects of invasive species against native wildlife.

“Imagine if, instead of opening a textbook, students could open their eyes to a virtual world. We live in a time where experiential learning and stories about different species matter, because how we feel about and connect with these species will determine their continued existence in the present and future. While technology cannot replace actual exposure to the environment, it can provide similar, near-realistic experiences when appropriately implemented,” say the scientists.

In conclusion, Delamarre and Clayborn note that the purpose of Butterfly World is to build knowledge, reawaken latent curiosity, and cultivate empathy for insect and ecosystem conservation.

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The game is accessible online at: http://ocelot.aul.fiu.edu/~adela177/ButterflyWorld/.

Original source:

Clayborn J, Delamarre A (2019) Living room conservation: a virtual way to engage participants in insect conservation. Rethinking Ecology 4: 31-43. https://doi.org/10.3897/rethinkingecology.4.32763

The Widow Next Door: Where is the globally invasive Noble False Widow settling next?

*Noble false widow spider (Steatoda nobilis) at a public bus stop in the seaside resort of Lyme Regis, southern England. Photo by Rainer Breitling.*

Spiders are one of the most successful groups of ‘invaders’ on the planet. Out of over 47,000 species of spiders known today, there are some that tend to follow humans across the globe and settle in habitats far away from their native homelands. A particularly notorious example is the species Steatoda nobilis, the Noble False Widow spider.

Originating from Madeira (Portugal) and the Canary Islands (Spain), the Noble False Widow has been rapidly spreading around the globe over the last few decades. While the species is already well established in Western Europe and large parts of the Mediterranean area, it has recently spread into California, South America and Central Europe. Meanwhile, its populations in England, where the spider used to be restricted to the very southern parts of the country, are now seen to experience a sudden expansion northwards.

As its name suggests, this is a relatively large species that resembles the well-known Black Widow and can inflict a painful – yet mostly harmless to humans – bite. Naturally, its ‘arrival’ causes widespread concerns and public disruptions. Specifically, the Noble False Widow poses a threat to native faunas, since it can prey on nearly every smaller animal thanks to its potent venom and sturdy webs.

Recently, experts and non-professional citizen scientists joined forces to reconstruct the invasion path of the Noble False Widow in Europe and the Americas, so that they could identify patterns and predict which regions are likely to be the next colonised by the spider.

By combining data from museum collections and the Spider and Harvestman Recording Scheme of the British Arachnological Society with published literature and their own observations from England, Germany, France and Ecuador, the researchers provided an unprecedented detailed view of the expansion of the Noble False Widow. The study, conducted by Tobias Bauer (State Museum of Natural History Karlsruhe), Stephan Feldmeier (Trier University), Henrik Krehenwinkel (Trier University and University of California Berkeley), Rainer Breitling (University of Manchester) and citizen scientists Carsten Wieczorrek and Nils Reiser, is published in the open-access journal Neobiota.

While it had largely been assumed that the Noble False Widow turned up in Europe along with bananas traded from the Canary Islands, a new look at the data revealed that the spiders have most likely been transported via imports of ornamental plants. Further, rather than the result of climate change, the establishment of the species across new, large territories is rather linked to the fact that these habitats all share similar conditions to the spider’s native localities.

“Similar suitable False Widow habitats occur in quite specific regions all around the globe,” explain the researchers. “Most importantly, South Africa, some areas in southern Australia, and a large part of New Zealand turn out to be highly likely targets for future invasions, unless appropriate import control measures are implemented.”

*Global prediction of suitable regions for the Noble False Widow (Steatoda nobilis). Image by Stephan Feldmeier & Tobias Bauer.*

In conclusion, the authors call for enhanced monitoring of the Noble False Widow as well as its still little known ecological impact on the environment in newly colonised areas. They also urge scientists in the predicted potential invasion target regions to search for specimens, especially in coastal cities.

Original source:

Bauer T, Feldmeier S, Krehenwinkel H, Wieczorrek C, Reiser N, Breitling R (2019) Steatoda nobilis, a false widow on the rise: a synthesis of past and current distribution trends. NeoBiota 42: 19-43. https://doi.org/10.3897/neobiota.42.31582

A race against pine: Wood-boring wasp in North America threatened by a Eurasian invader

Invasive species have diverse impacts in different locations, including biodiversity loss, as a result of native species being outcompeted for similar resources. A U.S. research team, led by Dr. Ann Hajek, Cornell University, studied the case of an aggressive Eurasian woodwasp that has recently established in North America and poses a threat to a native species. Their study is published in the open-access journal NeoBiota.

Most woodwasps play an essential part in the forest ecosystem, as they decompose wood, preferring dying or felled trees. They do so by laying their eggs in the wood underneath the tree bark. Curiously, the wasps also deposit a symbiotic fungus and venom that shuts down the tree’s defenses. As the tree weakens, the fungal infestation begins and the the tree starts to rot. When the eggs hatch, the larvae feed on the rotten wood before they emerge. This relationship is called obligate since the survival of the wasp is impossible without the fungal infestation.

Originating from Eurasia, the presence of the invasive species is dangerous because it can kill healthier pines. It has long been established in the southern hemisphere causing economic issues due to its attacks on pines. While pines have been introduced to that part of the world, they are native to North America, where the invasive wasp could be far more devastating.

Now that the invasive woodwasp has already been identified in the States, the scientists seek to find a way to protect its frail competitor, reporting a rapid decline in the North American species.

“We would often observe both species emerging from the same infested pine trees, but the ratios changed with time,” explains Dr. Ann Hajek.

“Shortly after the invasive colonizes an area, the native wasps emerging from the trees would equal the invasive. However, a few years later, the natives started to get fewer and fewer.”

It turned out that the Eurasian woodwasp has larger venom glands and produces more eggs, thanks to its greater body size. Furthermore, it emerges earlier than the North American species, so that it can find and colonize the most suitable trees first. By the time the native species lays its eggs, the authors speculate, most of the preferred trees are already occupied by the invasive, leaving a reduced supply of habitat for the newcomer’s larvae.

“Woodwasps are difficult to study and their biologies are generally poorly understood,” note the authors. “While the native species appears to be outcompeted from pines that both species prefer, it is possible that populations of the native can be sustained in trees less desirable to the invasive or unavailable during the time and place that the invasive is present.”

The scientists call for additional research on the native woodwasp in southeastern pine forests in USA, before the invaders spread to that area with extensive pine forests.

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Original source:

Hajek AE, Henry JC, Standley CR, Foelker CJ (2017) Comparing functional traits and abundance of invasive versus native woodwasps. NeoBiota 36: 39-55. https://doi.org/10.3897/neobiota.36.14953

Poison ivy an unlikely hero in warding off exotic invaders?

Dozens of studies have looked at the effects of Japanese knotweed on natural communities in Europe and North America. Yet Bucknell University professor Chris Martine still felt there was something important to learn about what the plant was doing along the river in his own backyard.

“The more time I spent in the forests along the Susquehanna River, the more it seemed like something was really going wrong there,” said Martine. “In addition to the prevalence of this single invasive species, it looked like the very existence of these forests was under threat.”

What Martine noticed was similar to what local nature lovers and biologists with the Pennsylvania Natural Heritage Program were also starting to see: these forests, specifically those classified as Silver Maple Floodplain Forests, were not regenerating themselves where knotweed had taken a foothold.

In a new study published in the open access Biodiversity Data Journal, Martine and two recent Bucknell alumni conclude that Japanese knotweed has not only excluded nearly all of the native understory plant species in these forests, but it has prevented the trees already established in the canopy from leaving behind more of themselves.

“If you were to fly over these forests, or even look at a Google Earth image, you’d see a nice green canopy along the river consisting of mature silver maples, river birches, and sycamores,” explained Martine. “But below that canopy there is almost nothing for tens of feet before you reach an eight-to-twelve-foot-tall thicket of knotweed. Few new trees have been able to grow through that in the last 50-60 years and our surveys found that seedlings of these species are quite rare.”

The authors suggest that as mature trees die of natural causes over the next several decades and are not replaced, these systems will shift from tree-dominated riverbank habitats to “knotweed-dominated herbaceous shrublands” incapable of supporting a rich diversity of insects, birds, and other wildlife. Loss of trees in these habitats could likely also lead to riverbank erosion and increase the severity of flood events.

The few places where knotweed has not taken over offer a bit of hope, however, from an unlikely hero: poison-ivy, which Martine calls “perhaps the least popular plant in America.”

“What we see in the data is that poison-ivy often trades understory dominance with knotweed. That is, when knotweed isn’t the big boss, poison-ivy usually is. The difference is that whereas knotweed knocks everyone else out of the system, poison-ivy is more of a team player. Many other native plants can co-occur with it and it even seems to create microhabitats that help tree seedlings get established.”

The prevalence of poison-ivy in these sites didn’t go unnoticed by undergraduate Anna Freundlich, who collected most of the plant community data — more than 1,000 data points — in a single summer as a research fellow.

“Anna developed a pretty serious methodology for avoiding a poison-ivy rash that included long sleeves, long pants, gloves, duct tape, and an intense wash-down protocol,” said her research advisor, “and even after crawling through the plant for weeks she managed to never once get a rash.”

Martine cautions against too much optimism regarding the chances of one itch-inducing native plant saving the day, however.

“Righting this ship is going to require eradicating knotweed from some of these sites, and that won’t be easy work. It will take some hard manual labor. But it’s worth doing if we want to avoid the imminent ecological catastrophe. These forests really can’t afford another half-century of us letting knotweed run wild.”

Freundlich is a now pursuing a Master’s degree in plant ecology at the University of Northern Colorado. Lead author Matt Wilson, a Bucknell Master’s student at the time of the study who analyzed the dataset, now works for the Friends of the Verde River in Cottonwood, AZ.

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Original source:

Wilson M, Freundlich A, Martine C (2017) Understory dominance and the new climax: Impacts of Japanese knotweed (Fallopia japonica) invasion on native plant diversity and recruitment in a riparian woodland. Biodiversity Data Journal 5: e20577. https://doi.org/10.3897/BDJ.5.e20577

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About Japanese knotweed:

Japanese knotweed is considered to be one of the toughest, most damaging and insidious plants in the world. Native to East Asia, the species has already established successfully in many parts throughout North America and Europe, where it can easily grow and invade private properties and homes. It is hardy enough to penetrate patios, house foundations and concrete. Given it spreads easily and can grow underground to a depth of 3 metres with a horizontal range of up to 7 metres, it is extremely difficult to eradicate and its treatment requires special attention. To find advice on recognition, hazards and treatment, you can check out The Ultimate Japanese Knotweed Guide.

From a bulletin to a modern open access journal: Italian Botanist in Pensoft’s portfolio

Established in the distant 1888, the Italian Botanical Society has gone a long way towards publishing its achievements and research. Originated as a bulletin within an Italian journal, they have been growing ever since to now form a new international journal in its own right. Covering both Italian and international research in botany and mycology, the online open access journal Italian Botanist, published by Pensoft, is now officially launched via its first papers.

Although what was later to become Italian Botanist, published its first issue as an independent journal, called Informatore Botanico Italiano in 1969, the publications were still rather bulletin-style. It consisted of a mixture of administrative and scientific proceedings of the Society, the yearbook of the members, as well as scientific notes.

Nevertheless, such a major transition has been set to change everything fundamentally. Establishing its name, the journal started picking up, so that it was not long before the scientific contributions were prevailing. Impressively, for the Society’s centenary the journal published a celebratory 331-page contribution.

Gradually, its scope was expanded to cover several scientific fields. It hosted several themed columns, including cytotaxonomic contributions on the Italian flora, relevant new floristic records for Italy, conservational issues concerning the Italian flora and mycology.

However, the Directive Council of the Italian Botanical Society has not seemed to be ready to give up on their journal’s evolution. Last year, the botanists decided that they need to transform the journal to an an online, open access journal written in English and called Italian Botanist, in order to boost the scientific value and international visibility of Informatore Botanico Italiano.

Under the name Italian Botanist, the journal has now joined Pensoft’s portfolio of peer-reviewed open access journals, all of which take advantage of the advanced technologies and innovations developed by the publisher.

The new journal’s scope ranges from molecular to ecosystem botany and mycology. The geographical coverage of Italian Botanist is specially focused on the Italian territory, but studies from other areas are also welcome.

Staying faithful to its spirit and philosophy, it keeps its column-format, with each issue to contain five columns, namely Chromosome numbers for the Italian flora, Global and Regional IUCN Red List Assessments, Notulae to the Italian flora of algae, briophytes, fungi and lichens, Notulae to the Italian native vascular flora and Notulae to the Italian alien vascular flora.

“Our hope is that this renewed version of the journal will serve the Italian – and foreign – botanical community more efficiently and provide readers worldwide with an easier access to knowledge concerning the Italian flora,” says Italian Botanist‘s Editor-in-Chief Lorenzo Peruzzi.

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Original source:

Peruzzi L, Siniscalco C (2016) From Bullettino della Società Botanica Italiana to Italian Botanist, passing through Informatore Botanico Italiano. A 128 years-long story. Italian Botanist 1: 1-4. doi: 10.3897/italianbotanist.1.8646