Every year, new alien species of insects and fungi invade European forests. Some of them are exotic pests and diseases that can affect the survival and growth of trees.
To help develop strategies for monitoring and managing these non-native forest pests, a consortium of over 50 scientists representing 23 research institutions and 15 countries from across the globe joined their skills in the Horizon 2020 project HOMED “Holistic management of emerging forest pests and diseases.”
Between 2018 and 2022, the HOMED consortium developed a full panel of scientific knowledge and practical solutions to better deal with emerging native and alien invasive pests and diseases.
This includes targeting the successive phases of invasion, and developing innovative methods for each phase: risk analysis, prevention/detection, surveillance, eradication/containment, and control.
To share the results of this cooperation and help researchers further improve the management of emerging forest pests and pathogens, HOMED has made the main outcomes of its research publically available.
They are now published in a special issue in the open-access journal NeoBiota, called “Conceptual and technical innovations to better manage invasions of alien pests and pathogens in forests”. The issue comprises 16 articles on various aspects of the ecology and management of invasive alien insects and fungal pathogens in Europe’s forests.
“Because forests provide irreplaceable goods and materials for people and the European economy, because maintaining healthy forests is essential for their contribution to climate change mitigation through sequestration and storage of atmospheric carbon, it is urgent to develop more effective protective measures against the ever-increasing threat of invasive forest pests,” the editors of the special issue write in an editorial.
More tools are needed that can help identify, prevent and monitor invasive alien species and improve early warning methods, which makes the research in this issue so crucial and timely.
“The role of researchers is to develop, test and promote the most relevant methods and tools at each stage of the invasion framework, i.e., for the early detection of these invasive alien organisms, for the identification of the species and for the monitoring of their damage and spread, but also for new eradication and control solutions,” the editors continue.
One highlight in the published research is a study exploring how using the methods of citizen science at schools can increase invasive species awareness. Another explores the efficiency of artificial intelligence in pest detection.
“The publications collected in this special issue demonstrate that current conceptual, methodological, and technological advances allow a great progress in the anticipation, monitoring and management of invasive pest species in forests,” the editors conclude.
As a South American herpetologist, it is inevitable to be absolutely buzzed every time I hear “Germán, you have to go to the Amazon jungle”. Going to the Amazon forest in Peru is perhaps the most joyful way to do your work. The chances to find so many frogs, lizards, snakes, turtles, and even caimans are really high, so one can’t help but get excited.
The thing is, to someone like me who focuses their work on describing new species, the expectations shouldn’t be that high. The Amazon has always been a place full of mysteries, so many explorers, seduced by its enigmatic atmosphere, have gone deeper and deeper into the Amazonia. This has resulted in the description of so many species and very few unexplored places left.
So, when Wilmar Aznaran and I found this new species in the Amazon lowlands of central Peru, a well-visited area, we were quite surprised and kind of speechless. I have to confess that my reaction was “Bloody hell!” Externally, the frog is clearly different from any other similar species, and that was evident for us at the very moment we caught it. Indeed, the first option for the title of our new paper in Evolutionary Systematics was “Expect the unexpected: a new treefrog from the Amazon lowlands of Peru.” We could not believe that a medium-sized arboreal frog had passed in front of other researchers’ eyes, and remained unseen.
Soon we found out that it is not a common species in the area: after catching two individuals, we were unable to find more. Not ready to give up, we went once more time to that site a few months later and our efforts to find it were unsuccessful, so we suggest it is not a common frog.
At that point, we knew that we had a new species on hands, but describing it with only two specimens was challenging. Luis A. García-Ayachi went to the area and his efforts were also unsuccessful. That is when Alessandro Catenazzi joined us, so we decided to add an integrative approach to our work, basing our research on morphological and genetic differences. I can only say thanks to all our co-authors: from then on, everything started to work out.
We noticed there were wildfires in the area, are a serious threat to the frog’s habitat. So it is really curious that the orange pattern on the groins, thighs and shanks of the new species, resembles flames, like those threatening its habitat. No better name for our frog than Scinax pyroinguinis, which literally means “groins of fire”.
We hope that this discovery encourages people and institutions to protect these remnant forests in central Peru, because they may yet harbour unknown species. If these forests disappear, we will probably lose a diversity that we do not even know now yet, and may never will. It is sort of a race against deforestation and habitat loss, but this doesn’t mean there’s nothing we can do. Research like ours is really important to help put the focus on this place, at least in the short term, and try to attract people to join forces in the conservation of Scinax pyroinguinis and its habitat.
Chávez G, Aznaran W, García-Ayachi LA, Catenazzi A (2023) Rising from the ashes: A new treefrog (Anura, Hylidae, Scinax) from a wildfire-threatened area in the Amazon lowlands of central Peru. Evolutionary Systematics 7(1): 183-194. https://doi.org/10.3897/evolsyst.7.102425
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.
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.
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.
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.
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.
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.”
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
Lowland tapir populations in the Atlantic Forest in South America are at risk of almost complete disappearance, scientists have estimated. The main long-term threat to their well-being is population isolation, as hunting and highways keep populations away from each other. Urgent measures need to be taken to connect isolated populations and ensure the long-term conservation of tapirs, warn the authors of a new study published in the open-access journal Neotropical Biology and Conservation.
Lowland tapir populations in the Atlantic Forest in South America are at risk of almost complete disappearance, scientists have estimated. Weighing up to 250 kg, the animal can adapt to most habitats in South America—but its populations continue to decline across its range.
Today, its survival is seriously threatened: it can be found in just 1.78% of its original distributional range in the Atlantic Forest biome, which covers parts of Brazil, Argentina and Paraguay. The main long-term threat to its well-being is population isolation, as hunting and highways keep populations away from each other.
Urgent measures need to be taken to connect isolated populations and ensure the long-term conservation of tapirs, warn the authors of a new study on the distribution and conservation status of lowland tapirsin the South American Atlantic Forest, published in the open-access journal Neotropical Biology and Conservation.
“Of the 48 tapir populations identified during the study, between 31.3% and 68.8% are demographically unviable (low number of individuals), and between 70.8% and 93.8% of the populations are genetically unviable (low gene flow). Only 3-14 populations are still viable in the long run when both criteria are considered. The evidence suggests that with the appropriate conservation actions, the lowland tapir could be broadly distributed throughout the Atlantic Forest,” says Kevin Flesher.
“Tapirs have low reproductive potential, including a long reproductive cycle with the birth of just one young after a gestation period of 13-14 months and intervals of up to three years between births. Our populational simulations clearly show how, in the case of small populations, even the loss of a single individual per year can result in rapid extinction of an entire local population,” adds Medici.
Kevin Flesher dedicated 15 years to visiting 93 reserves in the Atlantic Forest, talking to people and analyzing 217 datasets, before he compiled the necessary data to design conservation actions that can ensure the survival of tapirs in the area.
The states of São Paulo and Paraná in Brazil have the largest number of remaining populations: 14 and 10, respectively. The two largest populations are in Misiones, Argentina, and in the neighboring Iguaçu and Turvo reserves, in Paraná and Rio Grande do Sul, Brazil.
“As far as our knowledge goes, there is no evidence of movement of tapirs between these populations,” points out Medici.
The distance between population fragments, however, is not what is stopping them.
“The central problem is the multiple threats they face while crossing the habitat,” explains Flesher. Highways are one major obstacle that limits the access of tapirs to forests with adequate habitat. “For example, the heavy traffic on highway BR-101 (which cuts the Brazilian Atlantic Forest from North to South) is a death trap to wildlife. Tapirs often die when attempting to cross it,” explains Medici.
The construction of highways and expansion of traffic in and around natural areas is a serious threat to large tapir populations that might otherwise have the chance to thrive, like those in Misiones, Argentina, and Serra do Mar, Brazil.
“Roadkill is a significant cause of death in six of the eight reservations in which highways cross tapir populations, and the expansion of the roadway grid in the country threatens to cause population fragmentation in at least four populations,” points out Flesher. This is why finding ways to allow tapirs to cross highways safely is an urgent conservation priority.
The results of the study, however, give cause for “cautious optimism” for the future of tapirs in the area: after decades of dedicated conservation efforts, the situation is starting to improve.
“Despite these continuing challenges for tapir conservation, most populations appear to be stable or increasing and the conservation outlook for the species is better than several decades ago, when the first efforts to protect the species began,” Kevin Flesher concludes.
Flesher KM, Medici EP (2022) The distribution and conservation status of Tapirus terrestris in the South American Atlantic Forest. Neotropical Biology and Conservation 17(1): 1-19.https://doi.org/10.3897/neotropical.17.e71867
About 120 clusters of 19th-century orchid bee nests were found during restoration work on the altarpiece of Basilica Cathedral in Casco Viejo (Panamá). Having conducted the first pollen analysis for these extremely secretive insects, the researchers identified the presence of 48 plant species, representing 23 families.
Despite being “neotropical-forest-loving creatures,” some orchid bees are known to tolerate habitats disturbed by human activity. However, little did the research team of Paola Galgani-Barraza (Smithsonian Tropical Research Institute) expect to find as many as 120 clusters of nearly two-centuries-old orchid bee nests built on the altarpiece of the Basilica Cathedral in Casco Viejo (Panamá). Their findings are published in the open-access Journal of Hymenoptera Research.
This happened after restoration work, completed in 2018 in preparation for the consecration of a new altar by Pope Francis, revealed the nests. Interestingly, many cells were covered with gold leaf and other golden material applied during an earlier restoration following an 1870 fire, thus aiding the reliable determination of the age of the clusters. The cells were dated to the years prior to 1871-1876.
The bee species, that had once constructed the nests, was identified as the extremely secretive Eufriesea surinamensis. Females are known to build their nests distant from each other, making them very difficult to locate in the field. As a result, there is not much known about them: neither about the floral resources they collect for food, nor about the materials they use to build their nests, nor about the plants they pollinate.
However, by analysing the preserved pollen for the first time for this species, the researchers successfully detected the presence of 48 plant species, representing 43 genera and 23 families. Hence, they concluded that late-nineteenth century Panama City was surrounded by a patchwork of tropical forests, sufficient to sustain nesting populations of what today is a forest-dwelling species of bee.
Not only did the scientists unveil important knowledge about the biology of orchid bees and the local floral diversity in the 19th century, but they also began to uncover key information about the functions of natural ecosystems and their component species, where bees play a crucial role as primary pollinators. Thus, the researchers hope to reveal how these environments are being modified by collective human behaviour, which is especially crucial with the rapidly changing environment that we witness today.
Galgani-Barraza P, Moreno JE, Lobo S, Tribaldos W, Roubik DW, Wcislo WT (2019) Flower use by late nineteenth-century orchid bees (Eufriesea surinamensis, Hymenoptera, Apidae) nesting in the Catedral Basílica Santa María la Antigua de Panamá. Journal of Hymenoptera Research 74: 65-81. https://doi.org/10.3897/jhr.74.39191