Franz Essl

• Professor (Full) at University Vienna, Austria

Invasive alien plant species can cause considerable ecological, economic, and social impacts, and the number of impactful species will likely increase with globalisation and anthropogenic climate change. Preventing potentially invasive alien plant species from becoming introduced is the most cost‐effective way to protect Norway's ecosystems from fu...

Bufo eichwaldi (Amphibia: Anura) is a toad species endemic to the Hyrcanian forests of northern Iran and southeastern Azerbaijan, increasingly threatened by anthropogenic pressures, underscoring the urgent need for conservation measures. We assessed the genetic diversity, population structure, and potential distribution of B. eichwaldi using molecu...

Reversing biodiversity loss and the sustainability crisis requires approaches that explicitly consider human-nature interdependencies. Social-ecological networks (SENs), which incorporate social and ecological actors and entities as well as their interactions, are such an approach. SENs have been applied to a range of complex issues, such as sustai...

Anthropogenic biodiversity decline threatens the functioning of ecosystems and the many benefits they provide to humanity¹. As well as causing species losses in directly affected locations, human influence might also reduce biodiversity in relatively unmodified vegetation if far-reaching anthropogenic effects trigger local extinctions and hinder re...

Aim Predicting the future distribution of invasive species is a current challenge for biodiversity assessment. Species distribution models (SDMs) have long been the state‐of‐the‐art to evaluate suitable areas for new invasions, but they may be limited by truncated niches and the uncertainties of species dispersal. Here, we developed a framework bas...

The diverse biotas of the world’s mountains face a challenging future due to increasing threats like climate change, land-use change, and biological invasions, the last being particularly understudied in these regions. Here we compile occurrence records for 717 alien vertebrate species distributed in 2984 mountains worldwide. We analyze their distr...

Urban areas are foci for the introduction of non‐native plant species, and they often act as launching sites for invasions into the wider environment. Although interest in biological invasions in urban areas is growing rapidly, and the extent and complexity of problems associated with invasions in these systems have increased, data on the compositi...

Biological invasions and human migrations have increased globally due to socio-economic drivers and environmental factors that have enhanced cultural, economic, and geographic connectivity. Both processes involve the movement, establishment, and spread of species, yet unfold within fundamentally different philosophical, social and biological contex...

Alien species are increasingly prevalent worldwide, leading to economic and biodiversity losses. We examined how the spread of non-crop alien plant species (i.e., archaeophytes and neophytes) has evolved in arable fields across ten countries in central Europe from 1930 to 2019. Specifically, we analyzed how regional and local trajectories of alien...

Patterns of biological diversity have been shaped by cultural practices in the past, while in turn, cultures and languages have evolved in close interaction with local species and ecosystems. However, in the Anthropocene, humans are putting increasingly more and diverse pressures on ecosystems and cultures resulting in accelerating threat levels on...

Biological invasions are a major threat to biodiversity, ecosystem functioning and nature's contributions to people worldwide. However, the effectiveness of invasive alien species (IAS) management measures and the progress toward achieving biodiversity targets remain uncertain due to limited and nonuniform data availability. Management success is u...

Context Historical land use is thought to have influenced plant community diversity, composition and function through the local persistence of taxa that reflect ecological conditions of the past. Objectives We tested for the effects of historical land use on contemporary plant species richness, composition, and ecological preferences in the grassl...

Context Ecological connectivity is key to mitigating global change impacts such as isolation and climate change effects on populations, especially in historically modified biomes such as European forests. The term connectivity is widely used in conservation, but the multiple methods for measuring it, as well as the scales and objects of study to wh...

1. Urban areas are foci for the introduction of non-native plant species, and they often act as launching sites for invasions into the wider environment. Although interest in biological invasions in urban areas is growing rapidly, and the extent and complexity of problems associated with invasions in these systems have increased, data on the compos...

Iran, situated in Southwest Asia, showcases a diverse landscape, including three phytogeographical regions and two global biodiversity hotspots. This diversity is attributed to its intricate geology, mountainous terrain, wide altitudinal range, and heterogeneous climate, fostering a rich flora characterized by a significant proportion of endemism....

Early detection and rapid response are essential to deal effectively with new introductions of invasive alien species (IAS). Citizen science platforms for opportunistic recording of species are increasingly popular, and there is potential to harvest their data for early detection of IAS, but this has not been tested. We evaluated the potential of d...

Many alien species are safe in their native ranges, but some are threatened. This creates a conundrum for conservation and invasion science. We analyzed the distributions, introduction pathways, threats, and conservation strategies of threatened mammals with alien populations globally. We reassessed their hypothetical IUCN Red List category includi...

Environmental filtering and dispersal history limit plant distributions and affect biogeographical patterns, but how their relative importance varies across evolutionary timescales is unresolved. Phylogenetic beta diversity quantifies dissimilarity in evolutionary relatedness among assemblages and might help resolve the ecological and biogeographic...

Species distribution models (SDMs) are widely used to address species' responses to bioclimatic conditions in the fields of ecology, biogeography and conservation. Among studies that have addressed reasons for model prediction variability, the impact of climatic variable selection has received limited attention and is rarely assessed in sensitivity...

Aim Functional traits help to understand the ecological processes underlying biological invasions. The extent to which trait data are available for alien plants at the global scale is unknown. In this study, we assess the availability of trait data and identify global gaps and biases Location Global Time Period Present Major taxa studied Vascul...

Citizen Science (CS) or community science significantly contributes to the study and management of biological invasions. Public participation in research and management boosts awareness, engagement, scientific literacy and can reduce conflict in invasive species management. Technological developments such as social media, internet scraping, eDNA, a...

1. Many invasive alien species gradually become embedded within local cultures. Such species can increasingly be perceived by society as familiar and native elements of the social-ecological system and as integral parts of local cultures. 2. Here, we explore this phenomenon and define it as cultural inception. Cultural inception can greatly hinder...

Biological invasions have substantial and rising social‐ecological impacts threatening human livelihoods and communities and hampering progress towards a just and equitable world. Currently, biological invasions are not adequately recognised and included in the UN Agenda 2030. Using a literature review conducted in Web of Science, we highlight the...

Mosquitoes are regarded as the most dangerous creatures on earth, spreading deadly pathogens through their bites. Human activities are driving range expansions of many mosquito species by unintentionally introducing them beyond their native ranges. Despite the often dire consequences for human health, a global picture of the introduction trends and...

The ecological impact of non‐native species arises from their establishment in local assemblages. However, the rates of non‐native spread in new regions and their determinants have not been comprehensively studied. Here, we combined global databases documenting the occurrence of non‐native species and residence of non‐native birds, mammals, and vas...

Cortaderia selloana (Schult. & Schult. f.) Asch. & Graebn. (Pampas grass) is a perennial grass native to temperate and subtropical regions of South America. The species was introduced to western Europe for ornamental purposes during the nineteenth century, where it has become naturalized in anthropogenic and natural habitats, especially in sandy, o...

As a result of human activities, a considerable part of European vascular plants and their populations are non-native. Since the publication of previous studies summarizing the composition and structure of European alien flora, our knowledge has increased, and new alien plant inventories and updates to existing ones have been published. The aim of...

A large number of non‐native trees (NNTs) have been introduced globally and widely planted, contributing significantly to the world's economy. Although some of these species present a limited risk of spreading beyond their planting sites, a growing number of NNTs are spreading and becoming invasive leading to diverse negative impacts on biodiversit...

Poster presented at the 7th European Congress of Conservation Biology (ECCB 2024), held in Bologna (Italy) from 17th to 22nd June 2024. The paper is currently accepted in Conservation Letters.

This study updates the distribution and status of Arctotheca calendula (L.) Levyns (Asteraceae, Cichorioideae) in continental North Africa (Algeria and Tunisia). Field surveys carried out mainly in northeastern Algeria (from 2021 to 2024) and northern Tunisia (from 2004 to 2023) by the first two authors, led to the identification of a total of 13 n...

Although invasive alien species have long been recognized as a major threat to nature and people, until now there has been no comprehensive global review of the status, trends, drivers, impacts, management and governance challenges of biological invasions. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES)...

Biological invasions are a growing challenge in a highly interconnected and globalized world, leading to the loss of native biodiversity. Indigenous peoples’ lands (IPLs) play a vital role in biodiversity conservation through activities such as land stewardship and management practices. Similar to protected areas, they are also often remote, with f...

We present the updated checklist of the alien flora of Mongolia, with information on species status, taxonomy, distribution, habitats, and economic use. In total, we recorded 154 taxa of alien plants, of which 33 are naturalized and 121 are casual. The alien flora belongs to 32 families, with Amaranthaceae, Fabaceae, and Brassicaceae containing mos...

Conservation decisions often need to integrate scientific predictions with societal values, ethical systems, and diverse perceptions that combine to form moral stances about conservation actions (e.g., trophy hunting or controlling invasive species). These can result in dilemmas and, if stakeholders hold different views on the morality of particula...

Large pulses of tree mortality have ushered in a major reorganization of Europe’s forest ecosystems. To initiate a robust next generation of trees, the species that are planted today need to be climatically suitable throughout the entire twenty-first century. Here we developed species distribution models for 69 European tree species based on occurr...

Changes in species' native range size and occupancy have been dramatically accelerated by anthropogenic pressures in the last centuries. At the same time humans have introduced thousands of species beyond their historic range limits, and some of these have established self-sustaining populations (i.e. become naturalized). It is known that particula...

Alien species can have massive impacts on native biodiversity, ecosystem functioning, and human livelihoods. Assessing which species from currently cultivated alien floras may escape into the wild and naturalize is essential for efficient and proactive ecosystem management and biodiversity conservation. Climate change has already promoted the natur...

Future dynamics of biological invasions are highly uncertain because they depend on multiple social–ecological drivers. We used a scenario‐based approach to explore potential management options for invasive species in Europe. During two workshops involving a multidisciplinary team of experts, we developed a management strategy arranged into 19 goal...

Many alien species are safe in their native ranges; however, some are threatened, posing a challenging conundrum for conservation and invasion science. We focused on alien threatened mammals, examining their distribution, pathways, threats, and conservation strategies. We also reassessed their IUCN Red List category to evaluate the effect of includ...

Human factors and plant characteristics are important drivers of plant invasions, which threaten ecosystem integrity, biodiversity and human well-being. However, while previous studies often examined a limited number of factors or focused on a specific invasion stage (e.g., naturalization) for specific regions, a multi-factor and multi-stage analys...

Successful alien species may experience a period of quiescence, known as the lag phase, before becoming invasive and widespread. The existence of lags introduces severe uncertainty in risk analyses of aliens as the present state of species is a poor predictor of future distributions, invasion success and impact. Predicting a species’ ability to inv...

The composition of weed floras in Central European fields has shifted creating a novel management issue: new weeds, that is, species that are currently spreading and increasing in impact. In their role as primary decision makers on the ground, farmers' perception of these new weeds plays a pivotal role in collecting information on their occurrence...

Aim Spreading infectious diseases associated with introduced pathogens can have devastating effects on native biota and human livelihoods. We analyse the global distribution of 100 major alien fungal and oomycete pathogens with substantial socio‐economic and environmental impacts and examine their taxonomy, ecological characteristics, temporal accu...

Invasive alien species are one of the major threats to global biodiversity, ecosystem integrity, nature's contributions to people and human health. While scenarios about potential future developments have been available for other global change drivers for quite some time, we largely lack an understanding of how biological invasions might unfold in...

Aim Worldwide, floras are becoming homogenized at global scales, but regional patterns vary. Here, we present the first assessment for the Malesian phytogeographical region in terms of the timing of introductions, direction, magnitude and drivers of floristic change due to alien plant naturalizations. Location Malesian phytogeographic region, incl...

Invasive alien species (IAS) adversely impact biodiversity, ecosystem functions and socio-economics. Citizen science can be an effective tool for IAS surveillance, management and research, providing large datasets over wide spatial extents and long time periods, with public participants generating knowledge that supports action. We demonstrate how...

At least 39,215 alien species and more than 37,000 established alien species have been recorded worldwide and occurrences of established alien species have been reported from all countries and all ecosystems globally. The number of established alien species has risen at continuously accelerating rates for centuries, recently reaching the highest to...

Darwin’s naturalization conundrum describes two seemingly contradictory hypotheses regarding whether alien species closely or distantly related to native species should be more likely to naturalize in regional floras. Both expectations have accumulated empirical support, and whether such apparent inconsistency can be reconciled at the global scale...

Plant introductions outside their native ranges by humans have led to substantial ecological consequences. While we have gained considerable knowledge about intercontinental introductions, the distribution and determinants of intracontinental aliens remain poorly understood. Here, we studied naturalized (i.e., self-sustaining) intracontinental alie...

Many plant traits covary with environmental gradients, reflecting shifts in adaptive strategies and thus informing about potential consequences of future environmental change for vegetation and ecosystem functioning. Yet, the evidence of trait–environment relationships (TERs) remains too heterogeneous for reliable predictions, partially due to insu...

The Anthropocene is characterized by a rapid pace of environmental change and is causing a multitude of biotic responses, including those that affect the spatial distribution of species. Lagged responses are frequent and species distributions and assemblages are consequently pushed into a disequilibrium state. How the characteristics of environment...

The Kunming-Montreal Global Biodiversity Framework (GBF) calls for a 50% reduction in rates of invasive alien species establishment by 2030. However, estimating changes in rates of introduction and establishment is far from straightforward, particularly on a national scale. Variation in survey effort over time, the absence of data on survey effort,...

Human activities are causing global biotic redistribution, translocating species and providing them with opportunities to establish populations beyond their native ranges. Species originating from certain global regions, however, are disproportionately represented among naturalized aliens. The evolutionary imbalance hypothesis posits that differenc...

While it is increasingly well understood how plants and animals spread around the world, and how they diversify and occupy new niches, such knowledge is fairly limited for fungi and oomycetes. As is true for animals and plants, many plant pathogenic fungi have been spread anthropogenically, but, in contrast to them, only rarely as a deliberate intr...

Aims Spatio‐temporal processes play a key role in ecology, from genes to large‐scale macroecological and biogeographical processes. Existing methods studying such spatio‐temporally structured data either simplify the dynamic structure or the complex interactions of ecological drivers. The aim of this paper is to present a generic method for ecologi...

Assessing the distribution of geographically restricted and evolutionarily unique species and their underlying drivers is key to understanding biogeographical processes and critical for global conservation prioritization. Here, we quantified the geographic distribution and drivers of phylogenetic endemism for ~320,000 seed plants worldwide and iden...

Karyological characteristics are among the traits underpinning the invasion success of vascular plants. Using 11 049 species, we tested the effects of genome size and ploidy levels on plant naturalization (species forming self‐sustaining populations where they are not native) and invasion (naturalized species spreading rapidly and having environmen...

Alien species can have massive impacts on native biodiversity and ecosystem functioning. Assessing which species from currently cultivated alien floras may escape into the wild and naturalize is hence essential for ecosystem management and biodiversity conservation. Climate change has promoted the naturalization of many alien plants in temperate re...

Shifts between native and alien climatic niches pose a major challenge for predicting biological invasions. This is particularly true for insular species because geophysical barriers could constrain the realization of their fundamental niches, which may lead to underestimates of their invasion potential. To investigate this idea, we estimated the f...

Human assistance and species’ characteristics are among the key drivers of plant invasions, which profoundly threaten ecosystem integrity, biodiversity and human well-being. However, previous studies have typically focused on one or a few factors or a particular invasion stage (e.g., naturalization) at regional scales. Here, we employed a multileve...

During field surveys carried out in northeastern Algeria, the escape of Gazania ×splendens Hend. & Andr. Hend. was observed; it is reported here as in the process of naturalization for the first time in Algeria and continental North Africa. This hybrid of the Asteraceae family, highly appreciated and widely used in ornamentation, was discovered at...

Aim Investigating major freshwater fish flows (translocations) between biogeographic regions and their temporal dynamics and also quantifying spatial patterns and temporal changes in the array of introduced species, and the emergence and distance between major donor and recipient regions. Location Global. Time Period 1800–2020. Major Taxa Studie...

Intra-continental range-expansion of native species tracking human-induced environmental changes has become an important phenomenon, and recently has been suggested to be recognized as a distinct biogeographic category, namely neonative. However, it remains difficult to analyze how range-expansions are triggered by certain environmental changes and...

This study provides a description of the floral morphology of populations of Oxalis debilis Kunth, 1822 from Algeria. Three floral forms were found: semi-homostylous (dominant), mid-styled (frequent) and short-styled (extremely rare). Two anther colors (yellow and white) were recorded with the dominance of the latter. A few fruits with seeds were o...

Drosanthemum floribundum (Haw.) Schwantes, ein südafrikanischer Endemit, wird hier als gebietsfremde Art von einem Küstenkliff in der Region Skikda im Nordosten Algeriens beschrieben. Die Population besteht aus mehreren Dutzend hängenden Büscheln, die sich über eine Fläche von ca. 100 m2 verteilen. Dies ist der erste Nachweis der Art in Algerien un...

While the regional distribution of non-native species is increasingly well documented for some taxa, global analyses of non-native species in local assemblages are still missing. Here, we use a worldwide collection of assemblages from five taxa - ants, birds, mammals, spiders and vascular plants - to assess whether the incidence, frequency and prop...

Aim Land use is the most pervasive driver of biodiversity loss. Predicting its impact on species richness (SR) is often based on indicators of habitat loss. However, the degradation of habitats, especially through land‐use intensification, also affects species. Here, we evaluate whether an integrative metric of land‐use intensity, the human appropr...

Natural hazards — such as storms, floods, and wildfires — can be disastrous phenomena and so can biological invasions, for which impacts are often irrevocable and insidious. Yet, biological invasion awareness remains low compared to natural hazards, and investments to manage invasions remain vastly underfunded and delayed. Here, we quantified biolo...

Human‐mediated changes in island vegetation are, among others, largely caused by the introduction and establishment of non‐native species. However, data on past changes in non‐native plant species abundance that predate historical documentation and censuses are scarce. Islands are among the few places where we can track human arrival in natural sys...

Questions: What is the role of native and domestic herbivores in native-alien vegetation changes in sub-Antarctic forests? Does herbivory suppression increase native while reducing alien species diversity? Location: Central-eastern Tierra del Fuego Island, Argentina Methods: In four sites, we set up three different treatments, i.e. excluded grazing...

Aim: Spatio-temporal processes play a key role in ecology, from genes to large-scale macroecological and biogeographical processes. Existing methods studying such spatio-temporally structured data either simplify the dynamic structure or the complex interactions of ecological drivers. This paper aims to present a generic method for ecological resea...

Standing deadwood is an important structural component of forest ecosystems. Its occurrence and dynamics influence both carbon fluxes and the availability of habitats for many species. However, deadwood is greatly reduced in managed, and even in many currently unmanaged temperate forests in Europe. To date, few studies have examined how environment...

Major regional gaps exist in the reporting and accessibility of naturalized plant species distribution data, especially within Southeast Asia. Here, we present the Malesian Naturalized Alien Flora database (MalNAF), the first standardized island-group level checklist of naturalized vascular plant species for the Malesian phytogeographical region. W...

Assessing phylogenetic endemism, i.e., the distribution of geographically restricted and evolutionarily unique species, is key to understanding biogeographic patterns and processes and critical for global conservation planning. Here, we quantified the geographic distribution and drivers of phylogenetic endemism for ~320,000 seed plants worldwide an...

Our ability to predict the spread of alien species is largely based on knowledge of previous invasion dynamics of individual species. However, in view of the large and growing number of alien species, understanding universal spread patterns common among taxa but specific to regions would considerably improve our ability to predict future dynamics o...