The Restoration Ecology Research Group of HUN-REN, CER-IEB conducted long-term monitoring of vegetation changes over a period of 17 to 25 years at three restoration experiments in the Kiskunság, Hungary. These sites underwent different restoration treatments, including native seeding, mowing, and carbon amendment. The study aimed to examine how these interventions influence the abundance of annual and perennial invasive alien plants over time, and how invasion dynamics are shaped by propagule pressure within a 100-meter buffer.
The findings were encouraging for annual invaders: their cover generally declined over time, particularly in areas where native seeding was applied. Seeding proved to be the most effective method in controlling these short-lived, fast-spreading species. In contrast, the situation was quite different for perennial invaders. These species consistently increased in cover over the decades, regardless of the type of intervention or the amount of invasive propagule pressure within a 100-meter buffer.
Monitoring arrangement for estimating invasive propagule pressure with transect method. Established eight 100-meter-long transects towards the eight cardinal directions and recorded the number of shoots of each invasive species in 1 m x 1 m adjacent plots along each transect.
Unexpectedly, local propagule pressure had little influence on invasion trends, suggesting that larger-scale processes and long-distance dispersal play a more dominant role. Mowing, although commonly used to control invasive species, may inadvertently aid invasive species by creating “colonisation windows” for opportunists already present in the landscape.
The authors stress that current restoration methods are insufficient to tackle the long-term threat of perennial invasive species. Once established, these plants are notoriously hard to remove, and their increasing dominance can threaten native biodiversity and restoration success. Therefore, more targeted, proactive strategies are needed—ones that take into account the life history traits and dispersal mechanisms of problematic perennials.
In conclusion, the study calls for a shift from site-level restoration to broader, landscape-scale approaches. Successful restoration must consider not only conditions within the restoration site, but also the surrounding ecological context, including propagule availability, disturbance regimes, and the resilience of native plant communities.
Niels Bohr, the Nobel laureate in Physics and father of the atomic model, is famously supposed to have said, “It is difficult to make predictions, especially about the future.” Our uncertainty about whether he actually said this or not, some attribute the quote of the legendary baseball player (and philosopher) Yogi Berra, highlights that making predictions about the past can be equally challenging. However, reconstructing the distant past and tracing how and when life adapted to new conditions, such as the rise of oxygen on Earth, requires making exactly such predictions.
“In a recent study published in Science, a multinational collaboration led by Gergely Szöllősi, senior research associate at HUN REN’s Institute of Evolution and the head of the Model-based Evolutionary Genomics Unit at the Okinawa Institute of Science and Technology (OIST), Tom Williams’ lab at the University of Bristol and Adrian Davin from Phil Hugenholtz’s group at the University of Queensland constructed a detailed timeline for bacterial evolution and oxygen adaptation, with a specific focus on how microorganisms responded to the Great Oxygenation Event (GOE) some 2.33 billion years ago. This event, triggered in large part by the innovation of oxygenic photosynthesis in cyanobacteria, fundamentally changed Earth’s atmosphere from mostly devoid of oxygen to one where oxygen became relatively abundant. Until now, establishing accurate timescales for how bacteria evolved before, during, and after this pivotal transition has been hampered by incomplete fossil evidence and the challenge of determining the maximum possible ages for microbial groups—given that the only credible maximum for the vast majority of lineages is the Moon-forming impact 4.52 billion years ago, which likely sterilised the planet.
The researchers addressed these gaps by turning to the geological and genomic records in tandem. Their key innovation was to use the GOE itself as a temporal constraint, assuming that most aerobic (oxygen-using) bacterial lineages are unlikely to be older than this event—unless fossil or genetic signals strongly suggest an earlier origin. They introduced a Bayesian approach that uses this assumption as a “soft” maximum, allowing for exceptions where the data warrant it. This approach, however, requires making predictions about which lineages were aerobic in the deep past. To do so, the team deployed machine-learning algorithms that aggregate signals across the entire genome, thereby robustly inferring oxygen tolerance from incomplete ancestral gene repertoires. To best leverage the fossil record, they incorporated genes from mitochondria (branching with Alphaproteobacteria) and chloroplasts (branching with Cyanobacteria), enabling additional fossil-based calibrations from the eukaryotic record and thereby improving dating accuracy.
Their results indicate that at least three aerobic lineages appeared prior to the GOE—by nearly 900 million years—suggesting that a capacity for using oxygen evolved well before its widespread accumulation in the atmosphere. Intriguingly, these findings also point to the possibility that aerobic metabolism may have predated the evolution of oxygenic photosynthesis. For instance, the earliest inferred aerobic transition occurred around 3.2 billion years ago in the common ancestor of two cyanobacterial groups, indicating that the ability to utilise trace oxygen may have facilitated the later emergence of genes central to oxygenic photosynthesis. Moreover, the study estimates the last common ancestor of all modern bacteria lived sometime between 4.4 and 3.9 billion years ago, in the Hadean or earliest Archaean era. Major bacterial phyla are placed in the Archaean and Proterozoic eras (2.5–1.8 billion years ago), while many families date back to 0.6–0.75 billion years ago, overlapping with the era when land plants and animal phyla originated.
Notably, once atmospheric oxygen levels rose during the GOE, aerobic lineages diversified more rapidly than their anaerobic counterparts, indicating that oxygen availability played a substantial role in shaping bacterial evolution. The researchers argue that this combined approach of using genomic data, fossils, and Earth’s geochemical history brings new clarity to evolutionary timelines, particularly for microbial groups that lack a straightforward fossil record. It also offers a powerful framework for exploring how other microbial traits arose and interacted with the planet’s shifting environment across geological time.
Photo: Banded Iron Formation (BIF): sedimentary rocks that record the rise of atmospheric oxygen during the Great Oxidation Event (GOE)
Predicting and mitigating the effects of climate change while preserving biodiversity is a top priority for both scientists and policymakers. As climate change intensifies, leading to more frequent and severe droughts, understanding the impact on natural ecosystems has become increasingly important. One of the main challenges is forecasting changes in species richness due to shifts in precipitation patterns. While it’s established that, on a broad geographic scale, regions with more water generally support greater plant diversity, results vary at smaller plot levels concerning how rainfall affects species richness. To improve predictions, it’s essential to explore the underlying mechanisms – particularly how intense droughts and long-term rainfall changes impact biodiversity. A new study shows that increased aridity at the plot level is indeed linked to a decrease in plant species richness, and this connection is even more pronounced following extreme droughts. However, this phenomenon is not easy to detect because in the absence of drought, dominant plant species can obscure this effect.
The study, carried out by the HUN-REN Centre for Ecological Research in Hungary, examines the intricate connections between long-term changes in rainfall, extreme drought conditions, the biomass of dominant plant species, and plant species diversity in a dryland ecosystem. Published in the Journal of Ecology, the research reveals that increased dryness leads to a reduction in plant species diversity in drylands and uncovers the mechanisms through which rising aridity contributes to biodiversity loss in these fragile ecosystems.
The experimental area in Fülöpháza, Central Hungary. Chronic precipitation treatments (along with decreasing aridity: severe drought, moderate drought, control and water addition) simulates changes in precipitation that have occurred several times historically. The image shows severe drought management, which excludes all rainfall from late June to late August. Prior to chronic treatments, half of the plots were exposed to an extreme treatment which simulated a drought unprecedented since the beginning of regional measurements.
Using data from a seven-year climate change field experiment, researchers conducted a path analysis to examine how precipitation influences species diversity, both directly and indirectly. The experiment simulated an extreme drought event followed by long-term variations in summer rainfall with the use of rainout shelters. Initial analysis showed a strong positive relationship between rainfall and species diversity after extreme drought treatment, but this effect was absent without drought. Interestingly, the path analysis uncovered another layer: in the absence of drought, increased rainfall boosted the biomass of dominant grass species, leading to a decrease in overall plant diversity. Nevertheless, the direct effect of rainfall remained positive, enhancing species richness even when dominant species exerted a suppressive impact. Additionally, the study revealed that past extreme droughts strengthened the link between rainfall and species diversity. Lead author Dr. Gábor Ónodi explains, “Extreme droughts decrease plant species richness and weaken dominant species. The reduction in the biomass of dominant species allows other plants to colonise, potentially altering the plant community.”
These findings have significant implications for predicting how natural ecosystems will respond to future climate change. Dr. György Kröel-Dulay, the lead researcher of the field experiment, notes “As global temperatures rise and precipitation patterns become more extreme, ecosystems may become increasingly sensitive to changes in water availability.” The study underscores the importance of considering both direct and indirect effects when evaluating the impact of climate change on biodiversity. Senior author Dr. Zoltán Botta-Dukát adds, “By deepening our understanding of these dynamics, we can better anticipate upcoming challenges and develop more effective strategies for conserving biodiversity in a world facing growing environmental uncertainties.”
Urbanisation is rapidly transforming landscapes worldwide, becoming a key driver of global biodiversity loss. It often impacts biodiversity negatively by creating selective environments that limit species diversity in urban compared to natural habitats. Amidst this challenge, understanding and enhancing urban blue-green infrastructure is critical. Garden ponds are small yet significant water features that are increasingly common in urban areas. They offer numerous ecosystem services, like aesthetic purposes, microclimate regulation, and habitats for ornamental species. However, their role in supporting biodiversity is still largely unknown.
A recent countrywide citizen science project called MyPond launched by researchers from the HUN-REN Centre for Ecological Research in Hungary highlights the potential of garden ponds as crucial contributors to urban biodiversity. The online survey gathered data from over 800 garden pond owners, uncovering insights into how these small water bodies support various animals, including amphibians and their tadpoles, odonates, and birds. The study also examined the impact of pond features, pond management practices, and urbanisation on the occurrence of these animals, shedding light on the role of pond management for wildlife.
“Our findings revealed that key pond features such as pond age, area, aquatic, and shoreline vegetation all have a strong influence on the occurrence of the studied animals. Amphibians and their tadpoles, odonates, and birds were less likely to be present in or at newly installed ponds (0-1 year), which can be due to the lack of vegetation and sediment that could offer hiding and breeding places. Aquatic vegetation was positively associated with the presence of tadpoles, odonates, and birds which indicates the habitat structuring role of aquatic vegetation that benefits biodiversity. Conversely, algaecide addition negatively affected the presence of amphibians and their tadpoles. Ponds in strongly urbanised areas had less sightings of adult amphibians and their tadpoles, while these types of ponds were visited by more odonates and birds. Despite these challenges, garden ponds emerged as vital refuges for wildlife, hosting a total of 13 amphibian species across the country, and providing critical secondary habitats within urban landscapes.” – explains Dr Zsuzsanna Márton, first author of the study.
Beyond biodiversity, the study also highlighted the ecological importance of garden ponds and provided actionable insights for urban biodiversity conservation, encouraging thoughtful pond management and design to maximize their benefits.
“Our study demonstrates that citizen science is a powerful tool for urban planning, as it can contribute to gathering valuable data on urban biodiversity and utilise it for more efficient conservation strategies. It could help urban planning by identifying hotspots of aquatic biodiversity or critical areas for the conservation of key groups like amphibians in urban environments. Garden ponds might provide important stepping stones, connecting other aquatic habitats in the landscape. Also, participants may become more conscious of environmental issues and their role in it which might lead to more active engagement in supporting blue-green infrastructure development.” – summarises Dr Zsófia Horváth, the senior author of the study and head of the Biodiversity and Metacommunity Ecology Research Group at Institute of Aquatic Ecology, HUN-REN Centre for Ecological Research.
Viktor Szigeti, a research fellow at the Institute of Ecology and Botany of HUN-REN CER, has been awarded a grant from the STARTING sub-programme of the National Research Excellence Programme, for the research project “Flowers and pollinators for buzzing cities”. The main objective of the STARTING sub-programme is to provide funding for postdoctoral researchers to start their independent research careers and to strengthen research creativity and excellence. (The National Research Excellence Programme replaced the previous OTKA calls in 2024.)
The 4-year research grants will be used for research on pollinating insects, as outlined below.
Pollinators play a fundamental role in nature and human life. Nowadays, the pressure to protect pollinating insects is shifting from farmlands to cities. They can be supported by maintaining semi-natural habitats and introducing novel techniques, such as less frequent mowing, flower sowing, and bee hotels. Through these interventions, cities could offer diverse environments, benefiting both pollinators’ and human well-being. However, the lack of evidence for novel solutions may trigger counterproductive ‘bee washing’ processes. Ecological research on urban pollination is in the spotlight with outstanding public interest. Therefore, researchers, local and (inter)national authorities are under pressure to develop and monitor pollinator-promoting interventions.
Our project aims to study urban pollinators by five priorities:
1) Explore the effectiveness of pollinator-promoting interventions;
2) Disentangle local and landscape-scale factors;
3) Develop simple sampling methods;
4) Investigate microclimate dependencies; and
5) Work on European and global-level syntheses.
To achieve these, we are monitoring flowers and pollinators in parks, road verges, and ‘bee pastures’ (in Budapest from 2021); developing novel interventions and a citizen-science mobile application; collaborating in EU-level research. These studies also embrace the ambitious vision of creating multi-functional, resilient, and green infrastructures. Overall, we are a small but emerging team, looking forward, challenging boundaries, and exploring innovative solutions for urban pollinators. This grant offers the opportunity to share captivating stories of cities buzzing with people, flowers, bees and butterflies.
Tropical forests, often referred to as the “lungs of the Earth,” are essential for sustaining life on our planet. They provide clean air, water, and unparalleled biodiversity. While deforestation due to slash-and-burn agriculture, mining, and logging remains the most recognized threat, less visible but equally dangerous forces are at work. A new study reveals that nutrient enrichment – driven by human activities such as agriculture and fossil fuel combustion – poses a significant risk to the delicate dynamics of tropical forests.
The research, conducted by an international team of scientists from the University of Kaiserlautern-Landau (RPTU), the University of Applied Sciences and Arts Goettingen, and the HUN-REN Centre for Ecological Research in Hungary, focuses on how nutrient deposition affects tropical tree seedlings’ growth and biomass accumulation. Their findings, published in Current Forestry Reports, show that this phenomenon can potentially disrupt forest composition and resilience, particularly in the face of global climate change.
By synthesizing data from 59 studies conducted across tropical regions worldwide, the researchers employed meta-analysis to uncover broad patterns of nutrient effects. Their analysis revealed that nutrient addition significantly boosted tree seedling growth, with shoot biomass increasing by an average of 26% and growth rates by 14%. Notably, the combination of nitrogen (N), phosphorus (P), and potassium (K) produced the most pronounced effects, driving growth rate increases of up to 27%. These impacts were particularly pronounced in seasonally dry sites, where growth rates surged by 38% and shoot biomass by an impressive 70%. Lead author Dr. Daisy Cárate Tandalla explains, “NPK are fundamental nutrients for plant growth. However, many tropical soils are nutrient-limited. Adding these nutrients disproportionately benefits fast-growing, competitive species, potentially shifting forest composition.”
The team, led by Daisy Cárate Tandalla (centre), working with tree seedlings for a transplantation experiment in the San Francisco Reserve, Ecuador, 2013.
Human activities are dramatically altering natural nutrient cycles. While volcanic activity and wildfires have historically contributed to nutrient deposition, agriculture and fossil fuel burning have intensified and expanded this process to even the most remote tropical regions. These nutrient inputs can give a competitive edge to certain tree species, leading to homogenized forests with fewer species – a trend that threatens biodiversity and ecosystem stability. Senior author Dr. Péter Batáry warns, “These changes may reduce species diversity across entire food chains and weaken forest resilience in the face of climate change. The loss of diversity also diminishes the forests’ ability to adapt to environmental stressors.”
The study also highlights the complexity of tropical forest research. Co-author Dr. Jürgen Homeier from the University of Applied Sciences and Arts Goettingen notes, “The studies we reviewed used a mix of methods – greenhouse pot experiments, transplantation trials, and in-situ fertilizer applications. Identifying seedlings to the species level remains a significant challenge due to the extraordinary diversity and similarity of young tropical trees.”
The dedicated effort of transplanting tree seedlings in the tropical montane forest.
The findings underscore the need for urgent attention to nutrient management in tropical regions. While nutrient deposition may seem like a localized issue, its impacts ripple through global ecosystems, affecting biodiversity, carbon storage, and the planet’s overall health. Tropical forests are a cornerstone of life on Earth, and preserving their complexity and resilience is crucial. This study is a timely reminder that even remote human activities can have far-reaching consequences for the natural world.
Researchers at the HUN-REN Centre for Ecological Research in Hungary applied an outdoor experimental setup of artificial ponds (mesocosms) to simulate habitat fragmentation and found that it significantly reduces microbial biodiversity, particularly among unicellular microeukaryotes. The study also highlights that fragmentation not only affects biodiversity but also disrupts essential food web interactions, underscoring the importance of maintaining connectivity among habitats to preserve biodiversity and ecosystem functioning.
In the midst of the ongoing global biodiversity crisis, even the smallest habitats like ponds demand our attention. Fragmentation of these habitats—driven by human activities like urbanization, agriculture, and land-use changes—poses a significant threat to biodiversity. Often overlooked in conservation efforts, ponds serve as vital ecological hotspots, supporting diverse species and sustaining essential ecosystem processes. These waterbodies are home to various microbial communities that, despite their tiny size play an indispensable role in ecosystem functioning, acting as primary producers, decomposers, and links in food webs. While the impacts of habitat fragmentation on large organisms like mammals and birds are well-documented, the effects on microscopic organisms, including bacteria, algae, and other unicellular eukaryotes remain poorly understood.
A recent study carried out by researchers from HUN-REN Centre for Ecological Research in Hungary explored the effects of connectivity loss within pond networks. Using an outdoor experimental setup of artificial ponds (mesocosms), the researchers simulated fragmentation by terminating the movement of water and organisms between habitats in half of the pond networks while maintaining dispersal in the other half. By controlling for factors like habitat size and environmental conditions, and focusing solely on connectivity loss, the study provided an insight into the direct impacts of fragmentation on biodiversity.
“Our findings were particularly striking for unicellular microeukaryotes. Connectivity loss led to significant declines in their diversity at both local and regional levels, highlighting that fragmentation can directly drive biodiversity loss, even under controlled circumstances. Both rare and abundant species were impacted, suggesting that fragmentation represents a widespread and severe threat to microbial biodiversity. In contrast, prokaryotes appeared more resilient, though we observed signs of a potential “extinction debt,” where biodiversity loss may emerge over longer timescales.” – explains Dr. Beáta Szabó, the first author of the study.
Beyond biodiversity, the study also highlighted how connectivity loss disrupts trophic interactions. Zooplankton grazers, which interact closely with microbial communities, experienced reduced biomass in fragmented habitats, further exacerbating the decline in diversity and community evenness of microeukaryotes. These findings highlight the interdependence of organism groups within ecosystems and the cascading impacts that habitat fragmentation can have on biodiversity and ecosystem functioning.
“Our study clearly demonstrates that habitat fragmentation—specifically the loss of connectivity—can have serious and far-reaching consequences for biodiversity. Even when habitat size or environmental conditions remain constant, simply disrupting the dispersal of individuals between habitats can trigger significant declines in microbial diversity. Conservation efforts must not only focus on preventing habitat destruction, particularly in vulnerable ecosystems like pond networks, but also prioritize maintaining and restoring connectivity between habitats to protect the ecosystems and species that rely on them. This is especially crucial for microbes, which, despite their small size, have enormous ecological significance.” – summarizes Dr Zsófia Horváth, the senior author of the study and head of the Biodiversity and Metacommunity Ecology Research Group at Institute of Aquatic Ecology, HUN-REN Centre for Ecological Research.
The invasive mosquito species, the tiger mosquito (Aedes albopictus), poses significant threats to human and animal health due to its ability to spread over large geographic areas and act as a vector for numerous pathogens. Understanding the ecological relationships this species establishes in different locations is crucial for assessing its worldwide dispersion success and its role in disease transmission. To uncover how invasiveness couples with the ability to adapt to various food sources László Zsolt Garamszegi from the Institute of Ecology and Botany, Centre for Ecological Research, Hungary performed a meta-analysis of published blood-meal surveys.
The analysis included data from 48 independent studies, providing a comprehensive overview of the mosquito’s feeding behavior across different regions and stages of invasion. The results indicate that the tiger mosquito exhibits significant variability in host selection depending on the geographic location and stage of invasion. Importantly, host diversity was greater in the invasive range than in the native range, but in newly invaded areas, the mosquito tends to have a narrower host range than in the long-established populations.
Literature survey and meta analysis of blood-feeding patterns in Aedes albopictus. Invasive Ae. albopictus has considerable ecological flexibility. The species’ ability to adapt to various food sources goes hand in hand with its successful worldwide dispersion, which has strong implications for its role in pathogen transmission.The results have strong implications for how the tiger mosquito mediates host-parasite dynamics in natural systems. Wider host diversity in the invasive range indicates that the chances for the species to act as a bridge vector between distantly related hosts such as humans and birds is higher than in the native distribution range, and this risk enhancing the spread of diseases further increases if the species has more time to adapt to the ecological conditions experienced in a given invaded region. Therefore, the obtained results can align with the ecological foundations that make this species a widespread disease vector worldwide.
The distribution of species and other ecological phenomena (e.g. vegetation types) may be affected by climate change. This impact is commonly investigated and predicted by predictive distribution models. The key components of these models are the so-called bioclimatic variables. The expected distributions predicted by the models depend on the values of bioclimatic variables (e.g. the temperature of the wettest quarter of the year). Meanwhile, the time period on which the variable is calculated (e.g. the wettest quarter) may shift within the year. This shift can easily be hidden, even though the ecological meaning of bioclimatic variables is highly dependent on the time period. For example, the wettest quarter may have been in May-June-July recently (this is true for a large part of Hungary), but this may shift to autumn or winter in the coming decades. It is not hard to see that this poses difficulties for distribution modeling. While in the recent past the bioclimatic variable describing the temperature of the wettest quarter characterized, in fact, the early summer period, in the future the same variable will describe the temperature of a completely different (in our example, much cooler) period of the year. However, to train the models that predict the future distribution (in our case, using autumn-winter temperatures), we have used the recent early summer temperatures.
Two researchers at the HUN-REN Centre for Ecological Research, Ákos Bede-Fazekas and Imelda Somodi, have already shown in a previous study that the so-called specific climate periods, such as the wettest quarter, used to calculate bioclimatic variables can not only theoretically shift by several months within the year, but that this can actually happen in the future in parts of Hungary according to climate models. The shift of the specific climatic periods reduces the reliability of the distribution models, so the modeler needs to recognize the problem and address it.
“Will Hungary be the only country in the future to be in a situation such unfortunate – from a modeling point of view? Or is the problem affecting the whole world, and perhaps some regions in particular? How far do the different global climate models agree on this issue? And the scenarios behind the climate models?,” lists Ákos Bede-Fazekas the research questions that have kept the two researchers busy.
“The questions we wanted to ask were given, as were the necessary climate data. We also knew that the results, whatever they would be, would not only be of interest to us, but would also provide important information to the large community of distribution modelers. The only thing left to do was to somehow synthesize the vast amount of data and the results that could be extracted from it, and present it to the scientific community in a form that would be accessible. I think that was the biggest challenge for us.”
Flowchart illustrating the main steps of the research, from input data to the calculation of specific climate periods and synthesizing analyses
In the end, the researchers succeeded, and their analysis of four climate models, four scenarios and four future time periods covering the whole Earth was published in the prestigious scientific journal Global Change Biology. The study highlights the areas most affected by the shift of specific climate periods.
In the map of intra-annual variability of precipitation (top) and temperature (bottom) blue polygons represent the areas that will be most exposed to shifts in the specific climate periods associated with precipitation and temperature
In addition to the map results, the two researchers from the HUN-REN Centre for Ecological Research also revealed which of the three important decisions that a distribution modeler must make when predicting the future distribution are the most and the least important ones. These decisions are the choice of the global climate model, the choice of the scenario, and the choice of the future period.
“We found that the modeler’s choice of the global climate model was the least important, while the choice of the future period was typically more important than the choice of the scenario,” reports Ákos Bede-Fazekas on the results. “The shift in specific climate periods becomes more pronounced over time and as more pessimistic scenarios are considered. However, global climate models could not be ranked in a clear order in this respect. From a modeling point of view, I find the result somewhat reassuring, as it is the choice of climate models that tends to cause the most difficulty for climate modelers, but this choice seems to be the least important.”
Unfortunately, from the point of view of ecology and the diversity of natural communities, the result is not nearly as reassuring. The researchers have found numerous examples of specific climate periods shifting by more than two months, and have also reported an expected shift of six months – the largest possible. Such a major shift in the within-year distribution of climatic features is something that is feared that many species will not be able to follow. To continue with our example, this means that plant and animal species that have adapted to the precipitation falling in the pleasant early summer heat over thousands of years, could face a major challenge if most of the precipitation falls in the autumn-winter months, when their life cycle makes it difficult for them to use this precipitation. This could lead to the migration or, in the worst case, the extinction of species.
“In the tropics, shifts in both temperature and precipitation related specific climate periods are expected in many areas. However, shifts related to the precipitation are also expected in many areas of the temperate and arctic zones,” summarizes Imelda Somodi the spatial analysis. “The combined shifts around the equator confirm the likelihood that a climate not known from elsewhere (non-analogue climate) will develop there in the future. Consequences of the development of such non-analogue climates are most difficult to grasp.”
In the conclusion of their study, the researchers from the HUN-REN Centre for Ecological Research point out that future predictive distribution models will need to take into account the shift of specific climate periods and incorporate this phenomenon into the modeling work if they are to provide reliable predictions.
The first pan-European study of its kind (Keith, H., Z. Kun, S. Hugh et al. 2024 – nature, communications earth & environment) calculated that Europe’s existing forests could sequester up to 309 megatons of carbon dioxide per year for 150 years if the use of these forests were abandoned and we let them continue to grow and re-grow.. This is equivalent to the CO2 reduction rate targeted in the European Green Deal for the LULUCF sector by 2030 (310 Mt/ha) and is greater than the current level of sequestration of managed forests in Europe (289 Mt/ha).
The authors calculated the amount of carbon stored in above-ground, below-ground and dead biomass from survey data on 288,262 trees in the remaining European primeval and old-growth forests in 27 countries, on 7,982 plots.
Surveyed primary and old-growth forest stands on Europe’s forest cover map
The carbon stocks and carbon sequestration capacities of naturally functioning primary and old-growth forest ecosystems composed of native trees are essential benchmarks. The authors calculated this benchmark forecological zones and forest types, ranging from low-productivity alpine birch forest in Sweden to the highest productivity mixed spruce-fir-beech forests in Bosnia-Herzegovina. Based on this, the predicted carbon carrying capacity of primary and old-growth forests is 22,449 MtC compared to 9,790 MtC in managed forests.
Aboveground carbon stock per hectare – Hungarian data are in the group of “Temperate continental forest – broadleaf” (case numbers are given in the columns)
The GlobBiomass and GeoCarbon projects have so far significantly underestimated forest carbon stocks in all forest types compared to data from primeval and old-growth forest.Therefore global models and parameters need to be developed and revised. Analysis of the tree density, diameter distribution and biomass of standing trees has shown that the thickest trees play the largest role in carbon storage, as half of all biomass is stored in trees thicker than 60 cm.
Tree density (light green) and carbon stock (dark green) of primary and old-growth forests by diameter class with the profile of cumulative biomass (red curve)
The protection and restoration of primary and old-growth forests are therefore not only of paramount importance for the conservation and maintenance of biodiversity, but also have an increasing role in mitigating climate change through their huge carbon sequestration and storage potential.
Researchers of the HUN-REN Centre for Ecological Research also contributed to the pan-European study with recent survey data of forest reserves representing the natural conditions of the Carpathian Basin.
The survey of forest reserves is supported by the public monitoring programme of HUN-REN Centre for Ecological Research and the Ministry of Agriculture.
Slide photo: Beech forest remnant in the Kékes Forest Reserve (Photo: Attila Bíró)
Dispersal is a crucial process in community ecology, through which individuals of a species can move into new and often different habitats. Species spread can happen actively, with individuals moving on their own, or passively, aided by dispersal agents. Understanding the dynamics and constraints of dispersal is a key to predict how species will adapt to changing environments, and can indirectly support biodiversity conservation and ecosystem stability.
The study of alien species dispersion is an important though relatively under-studied aspect of biological invasions. The colonisation of isolated wetlands and the introduction of pioneer and alien species are observable phenomena, but the underlying mechanisms are largely speculative. Researchers from the Institute of Aquatic Ecology at the HUN-REN Centre for Ecological Research have undertaken experiments on fish and plants to test hypotheses related to alien species dispersion. Previously, it was widely believed that waterbirds played an important role in the dispersal of fish in isolated water bodies, with fish eggs surviving passage through birds’ digestive tracts (i.e. endozoochory). Researchers at HUN-REN CER recently confirmed this hypothesis—the first such confirmation globally. However, questions persist regarding its prevalence among bony fishes and the variability in dispersal capacities across species.
In a series of feeding experiments with mallards, the researchers investigated the passive dispersal abilities of several common native (Wels Catfish, Common carp, Pike perch, Tench) and alien (Hybrid African catfish, Grass carp, Pumpkinseed, Amur sleeper, Stone moroko) fish species. In their paper, published in the journal Ecography, they reported the recovery of viable embryos of five fish taxa in the faeces of mallard, with successful hatching into larvae in one native (Tench) and one alien (Stone moroko) species. This result provide evidence that endozoochorous dispersal might be a widespread but likely rare phenomenon among bony fishes, with significant variability between species likely due to unique egg characteristics.
Herbivorous birds are known to play a significant role in seed dispersal, dietary studies from Europe showed that waterbirds can disperse hundreds of plant species, including many aliens. Moreover, passage through their digestive system can affect seeds’ germination rates. In a similar feeding experiment, researchers from HUN-REN CER compared the endozoochorous dispersal ability of six pairs of closely related (i.e. congeneric) alien and native wetland plant species. In their study, published in Freshwater Biology, they found that alien plant species can disperse more efficiently, with significantly higher seed passage rates.
However, these seeds germinated more slowly after gut passage compared to native species. Higher seed passage contributes to higher “propagule pressure” in new habitats, increasing the likelihood of establishing new populations of alien species. The delayed germination of aliens’ seeds also can offer a competitive edge to non-native species, particularly if they exhibit a fast growth rate and higher trait plasticity. Considering that mallards typically move several kilometres per day and even longer during migrations long-distance dispersal might be common and important for all studied plant species. Mallards also make shorter daily movements between wetlands, which might assist alien species to become fully established after their introduction to an area.
Pollinators are declining rapidly, largely due to land conversion and intensification of agriculture. To mitigate their crisis, low-disturbance habitats, such as sown wildflower plantings (commonly known forms are wildflower strips at the edges of arable fields), could promote pollinators by restoration of their resources (food, sheltering and nesting habitats). However, comprehensive knowledge is lacking on how landscape context, spatial configuration and age of wildflower plantings, seasonality and flower composition affect pollinator communities, especially from East-Central Europe.
To understand these effects, researchers from the HUN-REN Centre for Ecological Research established diverse native wildflower plantings within heterogeneous and homogeneous agricultural landscapes, by two spatial configurations: one large field or three smaller strips. Floral resources and wild pollinator insects (wild bees, hoverflies, butterflies) were sampled, in early and mid-summer, for two years after establishment (2020-21).
Flower resources of the sown plant species increased continuously, and were complemented at high rate by flowering plant species from the soil seed bank, especially in the first year. Both flower abundance and diversity increased the abundance of pollinators, highlighting the important role of using diverse seed mixtures. Wild bee abundance and species richness increased year by year and season by season, while butterfly abundance also demonstrated a yearly increase after establishment. Hoverfly abundance and species richness, however, showed an opposite trend, possibly due to the inter-annual variation. Wild bee and butterfly abundance was higher in the heterogeneous than in the homogeneous landscapes. Researchers did not observe any significant local effects of spatial configuration itself on pollinator populations.
Field-work photos from the transect walk method and the flower resources assessment from the four years of the study Photos: Borbála Bihaly (top left, buttom right) and Áron Bihaly (buttom left, middle and top right)
Our results emphasize that to support pollinators effectively, future wildflower plantings should be maintained for multiple years, in order to maximize floral diversity and ensure continuously available flower resources throughout the entire season.
Further results from the upcoming years and similar long-term and landscape-scale experimental studies are needed to understand all the benefits and ecological processes of diverse native wildflower plantings especially in understudied European regions.
The diverse floral resource of wildflower plantings in the second and third years and the pollinator insects visiting the flowers Photos: Viktor Szigeti (top left and middle left) and Borbála Bihaly (bottom row, top right and middle right)
Nowadays we hear a lot about climate change impacts in general, however, we still lack in-depth knowledge about how climate change might modify the processes determining the ecological status of lakes and the structure and functioning of aquatic communities. This is largely because these processes are intertwined in a complex manner, making any estimation regarding these changes challenging. In their latest study, researchers of the HUN-REN CER Institute of Aquatic Ecology used model simulations to analyse warming effects on phytoplankton dynamics based on field and experimental observations.
Although numerous lakes around the world have been showing an increase in annual mean temperature over the last few decades, it still remains difficult to assess long-term warming-related impacts in water bodies with various physical and chemical properties and diverse communities. Exploring these impacts is crucial not only for fishes, macroinvertebrates or aquatic macrophytes, but also for planktonic organisms, which form the basis of the aquatic food web and have a substantial influence on material cycles. Despite the broad range of sophisticated techniques developed to study this important group, elucidating how interrelated environmental factors drive plankton functioning is still a hard task due to the typically rapid dynamics of these communities. Monitoring based on regular field work is a crucial part of research on aquatic systems, but it is also time-consuming and lab-intensive, making any sampling effort limited in both space and time. In a sense, this is like following a streaming series with several seasons by only looking at a few snapshots from each episode, trying to guess what the actual story is.
We need complementary approaches to improve our ability to assess, estimate or forecast the ecological effects of climate change.Numerical models are promising candidates for this role, gradually gaining importance in ecological research. Generally speaking, such models describe fundamental relationships in the form of mathematical equations based on current data and scientific knowledge. Such relationships include e.g. species growth as a function of food item availability or the dependence of plant photosynthetic activity on light intensity. The strength of modelling lies in the possibility to create computer-generated simulations about changes in a population, community or ecosystem and their environment through space and/or time, helping to find causality behind natural phenomena. Thus, while field and experimental observations provide data about a series of temporary states and conditions, modelling aims at the processes that induce temporal change in those states and conditions.
In a Hungarian-Greek collaboration, Károly Pálffy, researcher of the institute’s Plankton Ecology Group, studied the dynamics of planktonic algae (phytoplankton, major primary producers of aquatic habitats) using an ecological modelling approach. While analysing a data series on Lake Balaton, Hungary in his previous study he found that the long-term rise in annual mean water temperature was accompanied by increasing seasonal fluctuations in phytoplankton composition (increasing seasonal variability), which might suggest a decline in ecosystem stability. He and his colleagues also managed to demonstrate something highly similar in a mesocosm experiment, raising the question of whether there is a more general connection between warming and the dynamics of planktonic algae.
A typical graphical output of a model simulation of one year run under different seasonal temperature scenarios (daily temperature values characteristic at present and increased with 1, 2 or 3˚C). Curves with different colours represent seasonal changes in the abundance of different species of algae. The modelling of temporal dynamics in multiple randomly assembled phytoplankton communities under different nutrient load and temperature combinations added up to more than 100,000 simulations. The study focussed on both short-term (one year) and long-term (30 years) changes and impacts.
The newly developed model made it possible to simulate changes in phytoplankton on the species level under various temperature scenarios. The output of the simulations was in agreement with the previous observations, elevated mean temperature caused more pronounced seasonal changes in phytoplankton composition, but the degree of this impact was also highly dependent on how the communities received inorganic nutrients essential for their growth. Accordingly, the ratio of the two most important ones, nitrogen and phosphorus as well as the temporal fluctuations in nutrient supply had significant influence on the effect of warming. This is in close agreement with recent studies that suggest the importance of considering nutrient load conditions (the so-called trophic state of a water body) when assessing the effect of climate change on aquatic ecosystems. Besides nutrients, initial species richness of the simulated communities also affected their response to warming. From a methodological point of view, this is an important finding, since it suggests that choosing an adequate number of species can be crucial in the planning of community-scale climate change experiments.
The recent paper published in Limnology and Oceanography also sheds light on what long-term consequences an increase in the seasonal variability of phytoplankton can have in terms of stability. At higher mean temperatures, seasonal extremes in community composition became more prominent, shifting the communities toward lower overall evenness. On a longer time scale, elevated temperatures also increased the probability of species loss, providing a mathematical explanation for the role of warming in reducing plankton community stability and thus modifying aquatic ecosystem functioning. The research group has plans for further extending the model, facilitating the simulation of climate change impacts in a spatial context as well as on the level of the planktonic food web.
Numerical models nowadays have an increasingly important role in the interpretation of field observations
In the framework of the Hungarian Academy of Sciences (MTA) Distinguished Guest Scientists Fellowship Programme, ten internationally renowned visiting professors will arrive at the research centres and supported research groups of the HUN-REN Hungarian Research Network in 2024. Applications for the calls for proposals were received from all three major disciplines: the humanities and social sciences, the life sciences and mathematics and natural sciences. Out of a total support budget of 100 million HUF, successful applicants were awarded grants ranging from 4.7 million to 9 million HUF.
Mauro Santos, a professor at the Autonomous University of Barcelona, will join the Institute of Evolution of the HUN-REN Centre for Ecological Research. The joint research aims to explore the potential for evolving univariate and multivariate adaptive phenotypic plasticity to increase the probability of persistence in response to continuous, controlled environmental change (e.g. global warming) accompanied by random environmental fluctuations within generations. The results will inform the empirical evidence needed to draw robust conclusions about the role of phenotypic plasticity in evolution. The aim is also to explore the role of different types of epistasis – synergistic or antagonistic – in the evolution of early genetic systems, starting from first principles and using theoretical model systems.
Professor Mauro Santos has worked with evolutionary biologists at the Centre for Ecological Research before. Then they demonstrated that, under the right circumstandes, senescens can support the response to the directional selection, i.e. evolutionary adaptation to changing environmental conditions. In doing so, the researchers have added an important and new aspect to the question of ageing, which has been an elusive and poorly understood phenomenon in evolutionary biology for more than a century and a half.
The nature surrounding us, the living world, and the ecosystem provide us with the means to produce food. They play an essential role in regulating the climate by absorbing carbon dioxide, storing carbon, or protecting the soil from erosion. In recent decades, the concept of ecosystem services has gained ground. Its spread is due to the opportunity it offers to explore the complex interrelationships between the natural and socio-economic systems. It highlights how society and the economy are based on ecosystems and how human activities modify the natural environment. There is a clear link between the state of ecosystems and the well-being, health and happiness of people through ecosystem services.
Hungary’s current National Biodiversity Strategy to 2030 (3rd National Biodiversity Strategy) was adopted in August 2023. Its objectives are creating a coherent network of protected areas, improving the condition of different protected areas and restoring degraded ecosystems. The above objectives can only be achieved based on proper information and a thorough situation assessment. For this, we need a comprehensive understanding of the current state of our habitats.
Over the past five years, extensive cooperation has been established between sectoral experts and nearly 250 researchers and conservationists in a project coordinated by the Ministry of Agriculture (KEHOP-4.3.0.-VEKOP-15-2016-00001). One project element is the National Ecosystem Services Mapping and Assessment (MAES-HU), which aims to assess and map the extent of ecosystems, ecosystem condition and ecosystem services nationwide. The extensive collaboration resulted in several studies, which amounted to about 2,400 pages overall. The most important results are highlighted in a book titled ‘The Assessment and Mapping of Ecosystem services in Hungary’.
“One of the tasks was to assess ecosystem condition. However, what someone means by the condition of an area or habitat can be very varied,” says Eszter Tanács, one of the project researchers and a research fellow at the HUN-REN Ecological Research Centre. “Each stakeholder defines ‘good condition’ from their own perspective. They usually focus on factors that directly affect the state of the habitat or group of organisms that are especially important to them. For example, the health of plants (whether trees or crops of some kind) is an important indicator. If this is not in order, everyone pays attention. However, there may also be indirect links between condition and services that are more difficult to identify. For example, the diversity of wildlife in an area may be closely linked to its condition and thus indirectly to what services may be provided by the particular ecosystem type and in what quality.”
“To inform nationwide decisions, we need to produce maps that try to reflect the state of the environment and habitats nationally. This scale represents a particular challenge because the ‘goodness’ of large-scale maps depends to a large extent on the data we can base them on. However, how much detailed data we have for a given area is often arbitrary in space and time. Information on different types of habitat is not uniformly available. In the case of forests, where management means that we have to think in terms of decades or centuries, a lot of data are available at the national level. This is also true for agricultural land, partly due to the different subsidy schemes. For grasslands and wetlands, however, there is little information at the national level based on accurate measurements, although many sectors could make good use of such. Generally, more related information is available on very valuable protected areas, but these cover only a small part of the country’s territory,” said Eszter Tanács, explaining the difficulties of the task.
“Where there are insufficient sources of information, i.e. little measured data, the researchers have tried to indirectly estimate the extent of environmental pressures and mapped them. They have built on previous research and knowledge of responses to such pressures. Maps based on such relationships can also be used to estimate current condition and suitability for wildlife. Still, they have a relatively high degree of uncertainty because they represent risk. There are cases where only rough estimates can be provided through multi-step analyses – for example, flower abundance is estimated based on the presence of pollinators, and flower abundance is estimated based on what habitat is being discussed. The usefulness of such maps is more limited than those based on measured data. Therefore, an important element of our research is to investigate how well such maps reflect the condition according to more detailed, fine-scale data where they are available. This is a prerequisite for producing better and more accurate maps over time,” said Eszter Tanács.
The Ecosystem Map of Hungary, completed in 2019 (with a baseline year of 2015), was a major milestone in the implementation of the project. Although there were significant data gaps in some of the maps used for compiling it, a detailed, wall-to-wall land cover database has been developed. It is currently the best available for Hungary in terms of spatial and thematic resolution.
Proportion (%) of seminatural habitat types (based on the Ecosystem Map of Hungary) within a 300 m radius of each point
Researchers from the HUN-REN ÖK Lendület Ecosystem Services Research Group have reviewed European ecosystem services mapping projects using national experience in a recent prestigious international publication. The paper, published in the journal Ecosystem Services and first authored by Ágnes Vári, reviews the ecosystem mapping process in 13 European countries, presenting the results of a survey of project participants. The publication reviews the types of methods used, the ecosystem services assessed, the problems identified, and possible ways forward at the European level.
Publication:
Ágnes Vári, Cristian Mihai Adamescu, Mario Balzan, Kremena Gocheva, Martin Götzl, Karsten Grunewald, Miguel Inácio, Madli Linder, Grégory Obiang-Ndong, Paulo Pereira, Fernando Santos-Martin, Ina Sieber, Małgorzata Stępniewska, Eszter Tanács, Mette Termansen, Eric Tromeur, Davina Vačkářová, Bálint Czúcz: National mapping and assessment of ecosystem services projects in Europe – Participants’ experiences, state of the art and lessons learned Ecosystem Services, Vol.65, 2024, https://doi.org/10.1016/j.ecoser.2023.101592
The diversity of life on our planet is declining at an unprecedented rate, as confirmed by a series of international scientific studies, evaluations and assessments. Recognising this process and mitigating the damage is the subject of a series of international conventions, the most significant of which is the Convention on Biological Diversity (CBD), adopted at the 1992 Earth Summit in Rio de Janeiro. The CBD is significant in that it takes a position at the highest international policy level on the relationship between human society and biodiversity. The Convention not only defines principles and tasks, but also contains measures on the functional, organisational and financial aspects of implementation.
As it is a global agreement, the implementation of the measures is extremely complex and demanding. The CO-OP4CBD – Cooperation for the Convention on Biological Diversity project’s objective is to improve coordination within the European Union (EU) in the implementation of the Convention, to identify the appropriate knowledge base for each issue addressed and to use it appropriately and effectively. The Centre for Ecological Research (CER) as project partner organised a two-day expert workshop with the collaboration of the Biodiversity and Gene Conservation Department of the Hungarian Ministry for Agriculture. The event took place on 15–16 January 2024 in Budapest, in the Ministry for Agriculture.
The meeting was attended by 56 participants from 7 countries, representing various government agencies, research institutes, universities, national parks and conservation NGOs. The first day focused on the technical processes of the Convention on Biological Diversity (CBD), at international, European Union and national level. The objectives of the workshop were outlined by KingaÖllerer (CER), Pierre Spielewoy (National Museum of Natural History – MNHN, France) presented the draft of further training activities for Central and Eastern European professionals within the CO-OP4CBD project, and Ditta Greguss (Biodiversity and Gene Conservation Department, Ministry for Agriculture, Hungary) spoke about Hungary’s commitments, in particular with a view to the 16th meeting of the Conference of the Parties to the CBD (COP 16) to be organised under the Hungarian Presidency of the Council of the European Union in 2024. Didier Babin (French Agricultural Research Centre for International Development – CIRAD) and Hendrik Segers (Royal Belgian Institute of Natural Sciences – RBINS) presented the functioning, decision-making and professional processes of the CBD, while Eliška Rolfová (Ministry of the Environment, Czech Republic) presented the functioning of the CBD from the perspective of the European Union.
On the second day, two group leaders of CER, scientific advisor Zsolt Molnár and AndrásBáldi, corresponding member of the Hungarian Academy of Sciences, presented the functioning of the Intergovernmental Science–Policy Platform on Biodiversity and Ecosystem Services (IPBES) and that of the CBD from a researcher’s point of view. Joachim Töpper (Norwegian Institute for Nature Research – NINA) spoke about the indicators of the Kunming–Montreal Global Biodiversity Framework.
Habitat fragmentation poses a growing global threat to our natural ecosystems, making it one of the greatest challenges in biodiversity conservation. Among the most vulnerable of these ecosystems are ponds, due to their small sizes and intricate networks. Ponds have experienced global declines in numbers and extent, making them a critical focus for conservation efforts. Once a pond loses its neighbors, it becomes isolated, which can lead to biodiversity decline. A new study, conducted in Hungary, sheds light on the importance of connectivity among ponds in these small-scaled habitat networks and its impact on the biodiversity of ponds.
Situated in the heart of the Pannonian Plain on the interfluve of the Danube and Tisza rivers, Hungary’s Kiskunság region is a diverse landscape, encompassing a variety of aquatic and terrestrial habitats. From shallow lakes, soda pans, and swamps to dry and wet meadows, semi-arid sand dunes, and grasslands, the region supports a unique array of flora and fauna, including numerous rare and endemic species. Large parts of the region belong to the Kiskunság National Park and are parts of a UNESCO Biosphere reserve, while a number of aquatic habitats are listed under the Ramsar Convention. Here, a cluster of 112 bomb crater ponds form a network with ponds differing in their distances, and therefore their relative connectivity to their neighbors. This so-called ‘pondscape’ was likely created during World War II by mistargeted bombing on a sodic meadow of the nearby airport.
Bomb craters may be scars on our Earth and reminders of devastating history but these ponds are thriving with life and providing habitat for a range of aquatic species today. They hold sodic water mostly dominated by sodium carbonates and hydrocarbonates and they vary in environmental and morphological characteristics. The ponds host a variety of species, including Pannonian endemic fairy shrimp (Chirocephalus carnuntanus), protected amphibians, pond turtles, and a range of invertebrates such as dragonflies, mayflies, aquatic beetles, and microcrustaceans. Beside its importance for conservation, the pondscape offers a unique setting for investigating scientific questions in a natural laboratory. The ponds are small and easy to sample and they form a well-delineated network far from other waterbodies. Therefore, they represent an excellent model system to understand how pond networks sustain biodiversity, and form a metacommunity, i.e., multiple separate habitat patches potentially connected through the dispersing organisms.
The ponds are not physically connected by waterways thus the dispersal of organisms is expected to occur mainly via wind or by the active movement of the organisms. The prevailing assumption has been that such small-scaled habitat networks lack structuring by spatial processes, i.e. we cannot observe diversity gradients in the network due to differential dispersal rates because all organisms could potentially spread to all habitats.
However, the findings of a study carried out by researchers from HUN-REN Centre for Ecological Research in Hungary challenge this notion. The researchteam investigated the influence of both space, i.e., the arrangement of the habitat patches and the local environmental variables (e.g. water nutrient content, depth, salinity) on species richness and community composition in an international collaboration led by Barbara Barta. These were tested in a range of organism groups including the tiniest microscopic creatures to ones as large as amphibians. They are expected to respond differently to the environmental conditions and connectivity.
“The findings showed that besides environmental conditions which certainly play a significant role in shaping community composition, the spatial position of ponds in the network is also important, particularly for passively dispersing organism groups. These are the organisms (e.g. microbes, plankton) that rely on dispersal agents, such as wind to move them across the landscape. For these species, it is better to be in the centre of the network where their pond is surrounded by many other ponds from which conspecifics can easily arrive. This leads to higher diversity of these groups in the centre of the pondscape.” explains Barbara Barta, the lead author of this study. This discovery highlights the importance of the central-peripheral connectivity gradient within pond networks.
“These findings underscore the significance of studying and conserving ponds as integral components of a network, rather than as isolated entities. It is crucial that the network as a whole is protected with all the connections which ensures that the biodiversity is sustained. Understanding the impact of connectivity on biodiversity in fragmented ecosystems like ponds is vital for the preservation of these unique habitats.” summarises Barbara Barta.
Photo: Horváth Zsófia
A network of bombcrater ponds on a meadow in Apaj, Central Hungary
One of the effects of climate change is shifting the habitats of species. For example, warming is pushing upward the forest boundary in high mountains. The question is whether the species’ speed of spreading is fast enough to follow the suitable habitats. Dr. Beáta Oborny, a researcher from the Institute of Evolution at the Centre for Ecological Research and the Institute of Biology at the Eötvös Loránd University, together with her colleagues have developed a new method to investigate this. Their paper co-authored with Dániel Zimmermann was the editor’s choice in Ecography. (The editor’s choice is a paper highlighted as the most exciting and novel paper in the monthly journal issue.)
As our planet undergoes significant transformations due to climate change, habitats are being altered, appearing, disappearing, or changing in quality. Understanding the impact of these changes on the geographic distributions of species is of great significance. The shrinking ranges of protected organisms and the expanding ranges of noxious species, such as pests and pathogens, highlight the urgent need to monitor range movements precisely. However, this task poses challenges as the available observation time is often short compared to the pace of underlying population processes, making it difficult to distinguish between directional shifts and random fluctuations.
Addressing this challenge, a research team led by Dr. Beáta Oborny from Loránd Eötvös University and the Centre for Ecological Research in Budapest has developed a novel method to monitor range shifts. The team aimed to precisely and consistently delineate range edges, allowing for comparisons between different years, geographic locations, and species.
Delineating range edges accurately is a non-trivial task as they often exhibit complex patterns. Occupied peninsulas are interspersed with unoccupied bays, and isolated occurrences dot the landscape. While traditional methods rely on the outermost occurrences of a species, Oborny and her colleagues propose a different approach. They suggest marking the range edge at the boundary between connected and fragmented occurrences, known as the “hull.” By marking the average position of the hull, the “connectivity limit,” over time, the researchers offer a statistically more reliable method. This region has a higher population density and exhibits smaller fluctuations, enhancing the robustness of the approach.
An upper limit of Dwarf mountain pine (Pinus mugo) in the low Tatra Mountains, Slovakia. The inset shows a snapshot from simulated population dynamics. Dark/light green shows the connected/fragmented occurrence of the species. The hull is marked by red. Photo: Courtesy of Konrád Lájer simulated image: Beáta Oborny
Oborny and her colleagues delved into the pattern-generating mechanisms using spatially explicit models. Unlike previous approaches based on general spatial statistical methods, their novel approach capitalizes on knowledge about the mechanisms governing the emergence of these patterns: birth, dispersal, and death within populations. Through computer simulations along environmental gradients (e.g., hillsides), the team explored the connectivity limits of different kinds of species. Remarkably, they discovered that the hull displayed a robust fractal structure with a dimension of 7/4. Further investigations conducted by Beáta Oborny and Dániel Zimmermann confirmed that this fractal structure remained consistent regardless of whether the range was rapidly advancing or retreating compared to the generation time. Notably, the method demonstrated particular robustness in the retreating (trailing) edge of species ranges. These findings highlight the applicability of the connectivity limit in tracking range shifts across diverse geographic scenarios, enabling a global perspective on these changes. For instance, the method allows for the comparison of treelines in different mountains, even when composed of different species, utilizing universal scaling laws.
The universal features uncovered in this study find their explanation in percolation theory, a field of research in statistical physics. This exemplifies the power of knowledge transfer between seemingly disparate scientific disciplines. The insights gained from these investigations deepen our understanding of the intricate relationship between environmental changes and species distributions. As scientists continue to refine and validate this method, it holds the potential to contribute to more robust assessments of biodiversity shifts and inform effective conservation strategies.
Image:An upper limit of Dwarf mountain pine (Pinus mugo) in the low Tatra Mountains, Slovakia. The inset shows a snapshot from simulated population dynamics. Dark/light green shows the connected/fragmented occurrence of the species. The hull is marked by red.
Photo: Courtesy of Konrád Lájer simulated image: Beáta Oborny
Our park ponds typically hold good numbers of mallards, and urban grassy areas often hold concentrations of geese. In the UK, Canada Geese are an abundant and widespread alien species, well known for fouling parks with their faeces. Until now, no attention had been paid to their role in seed dispersal, a major ecosystem service. Indeed, in the UK there has been surprisingly little attention paid to the role of wildfowl (ducks, geese and swans) in the spread of native or alien plants, a role of ever greater importance under climate change.
A new study from the Centre for Ecological Research in Hungary, in collaboration with the Doñana Biological Station in Spain, and the Wildfowl & Wetlands Trust and Liverpool John Moores University and University of Lincoln in the UK, compares the plants dispersed by mallards and Canada geese found together in 18 different urban and rural wetlands in north-west England (covering Merseyside, Greater Manchester, and the Lake District). In total 507 droppings were collected from the waterside, and examined for seeds and other plant propagules (i.e. dispersal units, that can include whole plants such as duckweeds) in the laboratory. Over 900 intact seeds were recovered, many of which were then germinated in the lab to prove they had survived gut passage.
“Although Darwin recognized the importance of migratory waterbirds in dispersing aquatic plants, this is the first detailed study of seed dispersal by ducks ever to be conducted in the UK, as well as the first European study to compare coexisting ducks and geese” said Andy J. Green, co-author of the paper. Over 33 plant species were identified, most of which were terrestrial plants, including trees and four alien species.
“We found that mallards and Canada geese have complementary roles” said Ádám Lovas-Kiss, senior author of the study. “Mallards disperse relatively more aquatic plants, and those with larger seeds, whereas Canada geese disperse more terrestrial plants”.
Both ducks and geese dispersed mainly plants that do not have a fleshy-fruit, and these have previously been assumed to have no or limited ability to disperse via animals, with no mechanism of moving more than a few metres. However, wildfowl provide perfect plant vectors, due to their long-distance flights, so they can help plants to reach new habitats, and to maintain connectivity between isolated plant populations, including different urban parks. For example, even wind-dispersed trees such as the Silver Birch, whose seeds were common in the faeces of both birds, will be dispersed much farther by wildfowl than by wind.
The study also found that the birds can continue to move seeds months after they have been produced on the plants, so for example migrating mallards can move seeds northwards in spring, which can help plants to adjust their distributions under climate change. Canada geese are relatively sedentary in the UK, although occasional movements of hundreds of km have been recorded. Alien plants were only recorded in wildfowl faeces in urban sites, but the study provides important evidence that they could also be spread from parks into natural habitats by wildfowl.
“We have been wrong to assume that only the 8% of European flowering plants with a fleshy-fruit are dispersed inside birds’ guts” says Lovas-Kiss. “Our study shows that many other plants are dispersed by birds, and that we need to pay much more attention to the role of ducks and geese as vectors of dispersal in urban ecology, as well as in natural ecosystems. Even alien geese can provide an important service by dispersing native plants”.
Biological invasion is considered to be one of the main drivers of biodiversity loss with potential negative socio-economic impacts. Invasive alien plant species are well adapted to rapid establishment and exploitation of the resources of disturbed environments, therefore disturbed and intensively managed habitats may support high levels of invasive species. Ecological restoration – defined by the Society for Ecological Restoration as the process of assisting the recovery of an ecosystem that has been degraded, damaged or destroyed – is increasingly recognized as a relevant tool to combat land degradation and biodiversity loss, and also invasive alien species. As the invasion problem becomes increasingly serious, there is an urgent need to develop more innovative, effective and proactive strategies to help improve the resistance of restored communities to invasion, limiting the establishment and further spread of invasive alien species.
In order to develop a prevention and mitigation strategy, it is necessary to understand the processes underlying biological invasion and resistance to invasion. The success of invasive alien species can be explained by the invasiveness of the species, the invisibility of the resident community and propagule pressure. The susceptibility of community to invasion, or its opposite, the ability of communities to resist invasion depends on the competitive ability of the resident community. Several factors can be responsible for the invasion resistance, such as the diversity or, more importantly, the functional diversity of resident communities, the presence of competitive dominant or rapidly developing native species that can exploit resources more fully or rapidly, limiting the potential for invaders to establish. Recently, functional similarity, propagule pressures and priority effects have become the focus of attention in attempts to explain resistance to invasion and to promote the restoration of invasion-resistant communities.
According to the limiting similarity hypothesis, species that use the same resources similarly cannot coexist stably, thus, in theory, integrating native species into restoration that are functionally more similar to known high-risk invasive alien species could lead to better resistance to invasion. High propagule pressure increases the chances of establishment, niche occupation and resource acquisition, therefore, density-driven suppression of invasive alien species is possible by increasing the seeding density of native species to match the propagule pressure of invasive alien species. Finally, priority of arrival has the advantage of early resource acquisition, which can strongly influence competition and survival, and thus ensuring the priority of native species; for example, by assisted dispersal, can be used to create communities that are more resistant to invasion.
The quantitative review of 48 papers indicate the potential of seed-based ecological restoration in controlling the establishment and growth of invasive alien species. Giving priority to native species was found to be the best approach in increasing invasion resistance that can reduce the performance of invasive alien species by more than 50%. Even a short-term advantage (as little as one week) can strongly favor native species, but the priority effect can be strengthened by increasing the time advantage. Seeding functionally similar species generally had a neutral effect on invasive alien species. High-density seeding is effective in controlling invasive alien species, but there can be thresholds above which further increases in seeding density may not result in increased invasion resistance.
Native perennial grass Festuca vaginata and invasive annual grass Tragus racemosus grown together in a greenhouse experiment studying the potential of limiting similarity, seeding density and priority effects to increase the competitive advantage of native species over invasive alien species.
Based on these results, the first step to prevent and mitigate the spread of invasive alien species is to create priority for the establishment of native species. This requires minimizing disturbance, reducing the propagule pressure and entry of invasive alien species, and introducing native species as soon as possible after disturbance. Native priority can be best increased by the early introduction of early-emerging, fast-growing native species and high-yielding communities. Seeding of a single species with high functional similarity to invasive alien species is unpromising, and instead, preference should be given to high-density multifunctional seed mixtures, possibly including native species favored by the priority effect. It is important to note that even combining the best methods to increase invasion resistance would not result in the complete elimination of invasive alien species, but would limit their biomass and seed production, reducing the risk of further invasion.
The study also highlights the need to integrate research across geographical regions, global invasive species and potential resistance mechanisms to improve the predictive capacity of invasion ecology and to identify best restoration practices to prevent and control invasive alien species.
