Romina D Fernandez
email: romi.d.fernandez@gmail.com

Phillip J Haubrock
email: phillip.haubrock@senckenberg.de

Ross N Cuthbert

Gustavo Heringer

Melina Kourantidou

Emma J Hudgins

Elena Angulo

Christophe A Diagne

Franck Courchamp

Martin A Nuñez

Underexplored and growing economic costs of invasive alien trees

The high ecological impacts of many invasive alien trees have been well documented. However, to date, we lacked synthesis of their economic impacts, hampering management actions. Here, we summarize the cost records of invasive trees to (I) identify invasive trees with cost information and their geographic locations, (II) investigate the types of costs recorded and sectors impacted by invasive trees and (III) analyze the relationships between categories of uses of invasive trees and the invasion costs attributed to these uses. We found reliable cost records only for 72 invasive trees, accumulating a reported total cost of $19.2 billion between 1960 and 2020. Agriculture was the sector with the highest cost records due to invasive trees. Most costs were incurred as resource damages and losses ($3.5 billion). Close attention to the ornamental sector is important for reducing the economic impact of invasive trees, since most invasive trees with cost records were introduced for that use. Despite massive reported costs of invasive trees, there remain large knowledge gaps on most invasive trees, sectors, and geographic scales, indicating that the real cost is severely underestimated. This highlights the need for further concerted and widely-distributed research efforts regarding the economic impact of invasive trees.

 .

 . Several of these alien tree species are used for commercial exploitation (e.g., timber and tanning products), therefore contributing to regional, national, and local economies, and are sometimes perceived as beneficial, when they improve social and economic

well-being [START_REF] Mohamed | Socio-economic contribution of Prosopis juliflora on the livelihoods of local communities in Garissa County[END_REF][START_REF] Kourantidou | Invasive alien species as simultaneous benefits and burdens: Trends, stakeholder perceptions and management[END_REF] . However, past evidence has shown that the benefits associated with the introduction of alien trees were eroded when these species become invasive [START_REF] Aguiar | Invasion of Acacia mangium in Amazonian savannas following planting for forestry[END_REF][START_REF] Van Wilgen | National-scale strategic approaches for managing introduced plants: Insights from Australian acacias in South Africa[END_REF] .

The competitive dominance of invasive alien trees often leads to the formation of mono-specific stands in invaded areas, which reduce local biodiversity, change species composition, displace native vegetation and affect native wildlife habitats [START_REF] Jäger | Destruction without extinction: Long term impacts of an invasive tree species on Galápagos highland vegetation[END_REF][START_REF] Le Maitre | Impacts of invasive Australian acacias: Implications for management and restoration[END_REF][START_REF] Dyderski | Impact of invasive tree species on natural regeneration species composition, diversity, and density[END_REF][START_REF] Fernandez | Changes in community functional structure and ecosystem properties along an invasion gradient of Ligustrum lucidum[END_REF][START_REF] Stewart | Impacts of invasive plants on animal behaviour[END_REF] . Many invasive alien trees also alter important ecosystem services such as fire regimes, nutrient, and water cycling [START_REF] Nuñez | Should tree invasions be used in treeless ecosystems to mitigate climate change?[END_REF][START_REF] Fernandez | Changes in community functional structure and ecosystem properties along an invasion gradient of Ligustrum lucidum[END_REF][START_REF] Le Maitre | Impacts of invading alien plant species on water flows at stand and catchment scales[END_REF][START_REF] Taylor | Pinus contorta invasions increase wildfire fuel loads and may create a positive feedback with fire[END_REF] , and negatively impact areas of high conservation value [START_REF] Castro Díez | Global effects of non-native tree species on multiple ecosystem services[END_REF][START_REF] Taylor | Pinus contorta invasions increase wildfire fuel loads and may create a positive feedback with fire[END_REF] . In addition, some invasive alien trees are known for driving significant economic losses associated with their excessive water use and significant management expenditure, triggered, for instance, through long-term control programs [START_REF] Van Wilgen | National-scale strategic approaches for managing introduced plants: Insights from Australian acacias in South Africa[END_REF][START_REF] Zavaleta | Valuing ecosystem services lost to Tamarix invasion in the United States[END_REF][START_REF] De Wit | Conflicts of interest in environmental management: Estimating the costs and benefits of a tree invasion[END_REF][START_REF] Turpie | The role of resource economics in the control of invasive alien plants in South Africa: Working for water[END_REF][START_REF] Wise | Costs, benefits and management options for an invasive alien tree species: The case of mesquite in the Northern Cape, South Africa[END_REF][START_REF] Wild | South Africa's invasive species guzzle precious water and cost US $450 million a year[END_REF] .

The fact that some invasive alien trees can simultaneously provide ecological and economic benefits while causing negative impacts generates conflicts between different stakeholder groups, due to their differences in value systems, perceptions, and interests [START_REF] Dickie | Conflicting values: Ecosystem services and invasive tree management[END_REF][START_REF] Kourantidou | Invasive alien species as simultaneous benefits and burdens: Trends, stakeholder perceptions and management[END_REF][START_REF] Dodet | When should exotic forest plantation tree species be considered as an invasive threat and how should we treat them?[END_REF][START_REF] Estévez | Clarifying values, risk perceptions, and attitudes to resolve or avoid social conflicts in invasive species management[END_REF][START_REF] Van Wilgen | Challenges and trade-offs in the management of invasive alien trees[END_REF] . For this reason, the management and effective control of invasive alien trees remains a major challenge [START_REF] Dickie | Conflicting values: Ecosystem services and invasive tree management[END_REF][START_REF] Low | Australian acacias: Weeds or useful trees?[END_REF] . Due to the lack of precautionary risk assessments for many alien trees introduced for different economic uses in some countries [START_REF] Low | Australian acacias: Weeds or useful trees?[END_REF] and the steady increase in the number of alien trees listed as invasive globally [START_REF] Richardson | Trees and shrubs as invasive alien species-a global review[END_REF][START_REF] Rejmánek | Trees and shrubs as invasive alien species-2013 update of the global database[END_REF] , this pressing problem has a staggering potential to grow. One reason for this ongoing challenge is the limited understanding of the socioeconomic impacts for several invasive trees and specifically the lack of a standardized process for assessing their impacts across different dimensions, which in turn undoubtedly limits efficient control and management actions [START_REF] Diagne | What are the economic costs of biological invasions? A complex topic requiring international and interdisciplinary expertise[END_REF] . Many studies have already assessed the cost records of prominent groups of invasive alien species at different temporal, spatial, taxonomic and other scales [START_REF] Angulo | Economic costs of invasive alien ants worldwide[END_REF][START_REF] Diagne | Economic costs of invasive rodents worldwide: The tip of the iceberg[END_REF][START_REF] Haubrock | Economic costs of invasive bivalves in freshwater ecosystems[END_REF] . Although the impacts of invasive trees are often massive and the economic consequences of their invasion can be high, to date there is no assessment specifically focused on the economic cost of invasive trees.

In order to bridge this knowledge gap, we provide the first synthesis of the economic cost records of invasive alien trees. We aim to (I) identify which species in which geographic locations possess cost information, (II) investigate which type of cost was recorded and which sectors were impacted, and (III) analyze the relationship between categories of uses of invasive trees and the invasion costs attributed to these uses.

Results

Cost sources, taxonomic groupings and geographic regions. According to the available data, cost records associated with invasive alien trees between 1960 and 2020 accumulated to a total of $19.2 billion (n = 2886 expanded entries), with an average of $313.89 million per year. About 25% of this total cost was empirically observed ($5 billion, n = 2183), whereas the remainder was associated with potential cost (i.e., not necessarily incurred, but extrapolated or expected). Most of the total cost originated from highly reliable sources ($12 billion, n = 2704). Additionally, the vast majority of the observed costs was deemed to be highly reliable ($4.7 billion, n = 2119). The remainder of the results considers our robust subset that includes only 'observed' and 'highly reliable' costs.

Regarding the spatial distribution of costs of invasive trees, the greatest share of observed costs were reported from South Africa (US$ 3.1 billion, entries n = 697), Colombia (US$1.4 billion, entries n = 18), the United States (US$ 98.0 million, n = 137), Spain (US$ 58.8 million, n = 785), and Australia (US$ 33.5 million, entries n = 74) (Fig. 1). Argentina (US$ 80.5, entries n = 3) had the lowest documented costs. No costs were reported from several countries, mainly in Africa and Asia (Fig. 1). While Spain had by far the most cost records (entries n = 785), it had only moderate total costs reported (US$ 58.8 million). In contrast, Belgium and Ethiopia ranked 8th and 9th in terms of costs, while having very few records each (US$ 6.3 million, entries n = 17, and US$ 6.0 million, entries n = 1, respectively).

We found 72 invasive alien tree species (17% of the total number of known invasive trees [START_REF] Rejmánek | Trees and shrubs as invasive alien species-2013 update of the global database[END_REF] ) including 52 genera and 32 families with costs that were deemed highly reliable and observed. The top ten costliest families of invasive trees in decreasing order were: Fabaceae, Arecaceae, Myrtaceae, Meliaceae, Salicaceae, Cactaceae, Pinaceae, Asteraceae, Anacardiaceae, and Solanaceae (Fig. 2). The cost was very unevenly distributed among the top 10 costliest invasive alien trees, with almost 90% of these costs derived from the invasion of Acacia mearnsii (black wattle) and Elaeis guineensis (African oil palm) in South Africa and Colombia, respectively (Table 1).

The vast majority of costs of invasive alien trees were caused by terrestrial species ($4.6 billion, n = 1989). However, the semi-aquatic species Melaleuca quinquenervia (paperbark tree) in North America and South Africa, and Baccharis halimifolia (Groundseltree) in France and Australia also led to substantial costs ($0.1 billion, n = 109).

Socioeconomic sectors and cost types.

The sector bearing the greatest cost was agriculture ($1.4 billion, n = 76), followed by authorities-stakeholders (i.e., governmental departments and/or official organizations, $1.1 billion, n = 1952). Other sectors (environment, forestry, and public and social welfare) received ≤ $0.01 billion in costs, while $2.1 billion was incurred by mixed sectors (Fig. 3a). The largest shares of invasive alien tree costs were incurred from resource damages and losses, despite very low numbers of cost entries ($3.5 billion, n = 38). Management spending was less than half of the total damages, but with far more cost entries ($1.2 billion, n = 2070). The remainder of entries consisted of mixed costs for which the relative damage and management cost could not be distinguished ($0.01 billion, n = 11) (Fig. 3b). Most of the management cost was spent reactively on post-invasion actions ($1.1 billion), whereas a much smaller part (< $0.01 billion) was spent pro- actively, on pre-invasion management or on knowledge funding. At the family level, Fabaceae ($2.2 billion) and Arecaceae ($1.4 billion) caused the largest share of damages, whereas Myrtaceae ($0.6 billion) led to the greatest management expenditure.

Uses of alien trees. Invasive trees included in InvaCost tended to be those associated with multiple uses, and the numbers of uses ranged from one to eight (Supplementary Table S2 online). The largest share of the $3.97 billion in total species-specific cost entries was attributed to invasive trees that were introduced for multiple uses, with only 14% associated with a single use (Supplementary Table S2 online). Horticultural (ornamental, including coverage) use was the most common among all uses of invasive alien trees (58 species), followed by food (including spice and medicine), stabilisation, erosion control and fertility improvement, agroforestry (including fodder), firewood and charcoal, other (including shade, biofuel and rubber), high-quality timber/furniture and then commercial forestry (Fig. 4). According to this, invasive trees used for horticulture (ornamental, including coverage) and food (including spices and medicines) were found to be the costliest (Fig. 4).

Discussion

Growing numbers of tree invasions have been reported worldwide, with at least 434 invasive alien tree species linked to ecological and economic impacts [START_REF] Rejmánek | Trees and shrubs as invasive alien species-2013 update of the global database[END_REF] . Alarmingly, costs have been reported for less than 20% of these known invasive trees and in limited portions of their invaded ranges, indicating that real costs for most invasive tree species remain unreported. Factors such as uses of different definitions of tree, cost reports without clear identification of the species, reports focusing on invasive tree species which do not necessarily mention the 'invasive' nature of these species (and thus InvaCost search strings not capturing them), lack of cost studies on certain species and regions, and non-monetized costs each contribute to underestimated costs of invasive trees. Many articles or other sources inferred costs at the genus level, without identifying the species. Indeed, when taking the 191 entries in the InvaCost database for genera that do not identify species, but for which we know to include species listed as "shrub or tree" life form (e.g., Acacia spp., Tamarix spp., Ligustrum spp., and Prosopis spp.), the forgone total was between $23.9 billion (using the robust dataset) and $64.7 billion (including low reliability and potential costs). Since our analysis included only entries for genera that include solely tree species (e.g., Pinus spp. and Eucalyptus spp.), the costs of invasive trees summarized here are again underestimated, and represent a minimum estimate of the total cost.

The Fabaceae (legume) family includes numerous species on the global list of invasive tree species [START_REF] Richardson | Trees and shrubs as invasive alien species-a global review[END_REF] and bears the highest costs, mainly associated with some Acacia species. Most of the Acacia species are native to Australia and many of them have been planted around the world for purposes such as forestry, ornamental use, and to provide materials e.g., for furniture [START_REF] Richardson | Trees and shrubs as invasive alien species-a global review[END_REF][START_REF] Van Wilgen | National-scale strategic approaches for managing introduced plants: Insights from Australian acacias in South Africa[END_REF][START_REF] Low | Australian acacias: Weeds or useful trees?[END_REF] . Although Acacia species showed the highest cost records, the number of studies reporting costs for these species was low in comparison with the extensive literature on the ecological impacts and management strategies of Acacia species.

Like Acacia species, several Pinus species were introduced internationally and predominantly in the Southern Hemisphere for commercial plantations and agroforestry. Many of these species, such as P. pinaster, P. radiata, P. patula, P. contorta, P. halepensis and P. elliotii, invade natural ecosystems, displacing native biodiversity, altering fire regimes and nutrient cycles, and decreasing water availability [START_REF] Taylor | Pinus contorta invasions increase wildfire fuel loads and may create a positive feedback with fire[END_REF][START_REF] Richardson | Invasive conifers: A global survey and predictive framework[END_REF][START_REF] Nuñez | Ecology and management of invasive Pinaceae around the world: Progress and challenges[END_REF] . Since Pinus use for forestry represents the greatest spatial and temporal planting of invasive trees, it was expected that in addition to causing significant ecological damages, these species would be associated with the highest economic costs. Contrary to this expectation, Pinus species were not in the list of the top ten costliest invasive tree species in our study. This may be because the perceived benefit of forestry production limits the perceived utility of studying the impacts of Pinus plantations. For this or other reasons, such as most of their invaded range being in the Global South, which is generally data-deficient in terms of costs [START_REF] Diagne | The economic costs of biological invasions in Africa: A growing but neglected threat?[END_REF][START_REF] Angulo | Non-English languages enrich scientific knowledge: The example of economic costs of biological invasions[END_REF][START_REF] Heringer | The economic costs of biological invasions in Central and South America: A first regional assessment[END_REF][START_REF] Van Wilgen | Three centuries of managing introduced conifers in South Africa: Benefits, impacts, changing perceptions and conflict resolution[END_REF] , there may be an associated lack of published reports on invasive Pinus costs. Additionally, as mentioned above, certain records of pine control costs are indistinguishably mixed with control costs of invasive species that are not trees [START_REF] Wild | South Africa's invasive species guzzle precious water and cost US $450 million a year[END_REF][START_REF] Le Maitre | Invasive alien trees and water resources in South Africa: Case studies of the costs and benefits of management[END_REF] . Other invasive tree species known to possess considerable ecological impacts such as Prosopis juliflora, Tamarix ramosissima, Miconia calvescens, and Leucaena leucocephala also have few recorded economic impacts.

Cost reports are missing from many countries and the countries for which cost records do exist, pertain to only a few invasive tree species. Given the large reporting gaps, it is not possible to make robust inferences on the global representation of the costs related to invasions of tree species. Our results also revealed strong geographic cost unevenness. Specifically, the InvaCost database used in this study contained no invasive tree costs for many countries, particularly in Africa, Asia and to a lesser extent Oceania and Central America. This can likely be partly attributed to the InvaCost database being limited in the number of languages considered for the cost search [START_REF] Angulo | Non-English languages enrich scientific knowledge: The example of economic costs of biological invasions[END_REF] . Although InvaCost includes cost data searched in over 22 non-English languages [START_REF] Angulo | Non-English languages enrich scientific knowledge: The example of economic costs of biological invasions[END_REF] , multiple languages still need to be included to improve understanding of costs of invasive trees globally, particularly in Asia. The fact that South Africa is the country with the highest reported cost was expected, given that this country had several invasive tree species reported and importantly, a long history in research and management of invasive species [START_REF] Richardson | Vectors and pathways of biological invasions in South Africa-Past, future and present[END_REF][START_REF] Van Wilgen | Biological invasions in South Africa: An overview[END_REF] , and invasive tree species in particular [START_REF] Richardson | The biogeography of South African terrestrial plant invasions[END_REF] . On the other hand, the high economic cost reported in Colombia is somewhat surprising, but was mostly related to the invasion by Elaeis guineensis (African palm). The African palm was introduced to Colombia in the 1950s, and since then, Colombia has become one of the main producers of palm oil in the world [START_REF] Ramírez | Palma africana: ¿oportunidad o amenaza para el ambiente y para el país?[END_REF] . African palm cultivation contributes significantly to the economy of this country, but at the same time, the control of this species as an invader and, predominantly, the damage in the production of other crops due to its invasion, have resulted in significant economic losses [START_REF] Mendieta | Lineamientos para la evaluación del impacto económico de las plantas invasoras[END_REF] . As is often the case with anthropogenic impacts, those most impacted by invasive palm damage (e.g., smallholder farmers of other crops) are likely not the same individuals who most benefit from the production of palm oil (e.g., large corporations [START_REF] Hudgins | The ecological dimension of global trade: Origin and recipient regions of biological invasion costs[END_REF] ).

It is widely recognized that early detection and management of invasive species has economic benefitsaverting damages to various degrees-and therefore often results in lower control costs [START_REF] Hanley | The economic benefits of invasive species management[END_REF][START_REF] Cuthbert | Biological invasion costs reveal insufficient proactive management worldwide[END_REF] . For invasive trees, we found substantial damage costs, but with reporting delayed compared to management expenditure. This is consistent with a lack of research interest and/or capacity in assessing and/or documenting the costs of these species proactively. In addition, most records of management costs were identified at post-invasion stages; which can indicate the small investments for early detection and management of several invasive tree species, as is the case also for other groups of invasive species [START_REF] Cuthbert | Biological invasion costs reveal insufficient proactive management worldwide[END_REF] , higher costs of reactive responses to invasion [START_REF] Heringer | The economic costs of biological invasions in Central and South America: A first regional assessment[END_REF] or the difficulty of obtaining this information.

Most alien plant species were intentionally introduced via pathways linked to the plant trade, particularly for ornamental horticulture and forestry, but also for food, agroforestry and medicines [START_REF] Richardson | Trees and shrubs as invasive alien species-a global review[END_REF][START_REF] Dehnen-Schmutz | A century of the ornamental plant trade and its impact on invasion success[END_REF][START_REF] Kowarik | Pathways in plant invasions[END_REF][START_REF] Van Kleunen | Economic use of plants is key to their naturalization success[END_REF] . The plant species with a greater variety of uses are introduced more frequently, which increases their opportunities to invade and cause major problems [START_REF] Richardson | Trees and shrubs as invasive alien species-a global review[END_REF][START_REF] Low | Australian acacias: Weeds or useful trees?[END_REF][START_REF] Van Kleunen | Economic use of plants is key to their naturalization success[END_REF] . In line with this, we found that most of the invasive trees with cost records were introduced for multiple uses. Particularly, most invasive trees in our dataset were introduced for ornamental purposes as well as for provision of food and medicine. Many of these species are still considered useful in some regions and in some cases, new purposes have since been found, different from those that prompted initial introduction and cultivation, but this may be related to the lack of other plant options available [START_REF] Low | Australian acacias: Weeds or useful trees?[END_REF] .

In particular, forestry with alien tree species provides a significant economic benefit through the trade of products and employment, but at the same time, these plantations can act as an important bridgehead for future invasions [START_REF] Richardson | Forestry trees as invasive aliens[END_REF][START_REF] Essl | Selection for commercial forestry determines global patterns of alien conifer invasions[END_REF] . The forestry industry is still planting alien tree species because of the realized economic benefits that come with such investments. However, the ecological, economic, or social costs associated with the abandonment of these plantations and the spread and invasion of these species may counterbalance their benefits [START_REF] Aguiar | Invasion of Acacia mangium in Amazonian savannas following planting for forestry[END_REF][START_REF] Dodet | When should exotic forest plantation tree species be considered as an invasive threat and how should we treat them?[END_REF][START_REF] Dechoum | Citizen engagement in the management of non-native invasive pines: Does it make a difference?[END_REF] . In addition, they are not borne by the same stakeholders, so the benefits of invasive trees should not be a reason for accepting their costs. Yet, the economic benefits obtained from the use of invasive trees can be important for local economies, and must be taken into account in the formulation of policies [START_REF] Kourantidou | Invasive alien species as simultaneous benefits and burdens: Trends, stakeholder perceptions and management[END_REF] (e.g., subsidies for transitioning to native species). Accordingly, it should be considered that the greatest long-term benefits will be obtained from the species with low risks of causing ecological and economical damage [START_REF] Low | Australian acacias: Weeds or useful trees?[END_REF] . Similarly, urban forestry is planting large numbers of alien tree species as ornamentals, and these plantations can facilitate invasions for associated species such as invasive insects [START_REF] Paap | Urban trees: Bridge-heads for forest pest invasions and sentinels for early detection[END_REF][START_REF] Dang | Introduced plants induce outbreaks of a native pest and facilitate invasion in the plants' native range: Evidence from the emerald ash borer[END_REF] , which can use stressed native and alien urban trees to establish and go on to cause billions of dollars of damage in cities [START_REF] Hudgins | Hotspots of pest induced US urban tree death, 2020-2050[END_REF] . Beyond recent calls for urban tree planting for climate change adaptation purposes [START_REF] Masson-Delmotte | Global warming of 1.5[END_REF] , a healthy urban canopy is necessary for adaptation to future climate change, which will be especially severe in cities that experience the urban heat-island effect [START_REF] Pataki | The benefits and limits of urban tree planting for environmental and human health[END_REF] . An analogous trade-off must be considered to balance the risk posed by the use of alien trees in cities and the damage they may cause, both to other urban trees, and through escape of alien trees and their pests into surrounding areas.

The control of invasive tree species that have ecological or economic benefits can be a challenge, since for most people 'green is good' irrespective of the species, and many people do not easily distinguish invasive trees from native ones [START_REF] Shackleton | Knowledge, perceptions and willingness to control designated invasive tree species in urban household gardens in South Africa[END_REF][START_REF] Richardson | Tree invasions: Patterns, processes, challenges and opportunities[END_REF] . There are multiple examples of negative impacts associated with invasive trees that are not perceived as such by citizens due to the prominent benefits associated with these trees and their strong cultural value and charisma [START_REF] Dickie | Conflicting values: Ecosystem services and invasive tree management[END_REF][START_REF] Jarić | The role of species charisma in biological invasions[END_REF][START_REF] Nuñez | Why some exotic species are deeply integrated into local cultures while others are reviled[END_REF] . Thus, preventive actions of these species can be frowned upon by society and even hindered in some cases [START_REF] Jarić | The role of species charisma in biological invasions[END_REF][START_REF] Nuñez | Why some exotic species are deeply integrated into local cultures while others are reviled[END_REF] . This highlights the need for stronger and more open communication with stakeholders and communities to understand the benefits they derive from alien tree species, whether other benefits are put at risk by these species, and whether alternative native species are available to fill existing needs [START_REF] Brundu | Global guidelines for the sustainable use of non-native trees to prevent tree invasions and mitigate their negative impacts[END_REF] . Furthermore, it is necessary to advise stakeholders and communities to seek alternative income sources through native plantations [START_REF] Brundu | Global guidelines for the sustainable use of non-native trees to prevent tree invasions and mitigate their negative impacts[END_REF] and/or diversifying local industries, as occurred in South Africa where the outcomes of deliberations with stakeholder are being implemented in policy [START_REF] Van Wilgen | Three centuries of managing introduced conifers in South Africa: Benefits, impacts, changing perceptions and conflict resolution[END_REF] . These options would help minimize conflicts of interest and reliance on alien trees, which ultimately may help avoid or reduce undesirable invasions.

Conclusions

Our synthesis shows that, to date, there are few available records of economic costs for invasive trees and only for a small subset of these species (e.g., over 80% of all known invasive trees and large parts of the world have no cost records). Further research is urgently needed to accurately establish the current numbers of invasive alien tree species worldwide, thereby helping to identify knowledge gaps in understanding of their economic impact. Despite limited data being available, our results clearly indicate that invasive trees cause economic losses at the multi-billion-dollar scale. There is a need for more rigorous and consistent reporting of observed/ materialized costs for many invasive trees at the species level across their entire invaded ranges. Future studies could consider the abundance of invasive trees and the invaded area in order to obtain better estimates of their economic impacts. We also argue for more comprehensive risk assessments of spread beyond plantation ranges and invasion risk prior to the introduction and spread of any alien tree species introduced for a particular use. Last, it is important to keep in mind that we use costs as a standardized way of studying economic impacts, but invasive trees cause significant problems for biodiversity and ecosystem functioning that are difficult or even impossible to quantify in monetary terms. This should remain a concern and the focus of discussions as to the costs and benefits of these species, and how to navigate associated trade-offs.

Methods

Tree definition and data source of their economic costs. There are many definitions of "tree". In this study, we followed the tree definition agreed on by IUCN's Global Tree Specialist Group (GTSG): "a woody plant with usually a single stem growing to a height of at least two metres, or if multi-stemmed, then at least one vertical stem five centimeters in diameter at breast height". The GlobalTreeSearch database uses this definition and includes all species that are recorded as naturally growing as a tree somewhere, representing the most comprehensive list of the world's tree species [START_REF]GlobalTreeSearch online database (version 1.6)[END_REF] . Thus, this database includes palms and some cacti. Based on this list, we identify the species with tree growth form in the InvaCost database to obtain the list of invasive trees with records of economic costs.

The InvaCost database compiles reported monetary costs of invasive alien species worldwide in a systematic and standardized manner 34 ; version 4.1 available at https:// doi. org/ 10. 6084/ m9. figsh are. 12668 570, This most up-to-date version-at the time of writing-includes 13,553 cost entries (i.e., rows of unique cost data), which were collected from both English and non-English sources [START_REF] Angulo | Non-English languages enrich scientific knowledge: The example of economic costs of biological invasions[END_REF][START_REF] Diagne | InvaCost, a public database of the economic costs of biological invasions worldwide[END_REF] through a combination of systematic searches on the Web of Science, Google Scholar and Google search engine, and opportunistic or targeted searches (e.g., contacting relevant experts). We increased the wealth of available data for invasive tree species through additional literature searches. We reviewed the literature published in English, Spanish and Portuguese until April 2022 using the words 'invas*' and ' econom*' as search terms, to which we added the scientific name of some known invasive tree species [START_REF] Rejmánek | Trees and shrubs as invasive alien species-2013 update of the global database[END_REF] to obtain species-specific costs within their invaded ranges. This process resulted in 38 new cost entries. Each cost entry in InvaCost was standardized against a single currency (2017 United States dollars, hereafter $). Within the InvaCost database, a set of descriptor columns describes each cost in more detail to allow comparability across contexts and scales, including the taxonomy of invasive tree species, the temporal and geographic scales, the socioeconomic sectors affected, and the type of cost [START_REF] Diagne | InvaCost, a public database of the economic costs of biological invasions worldwide[END_REF] .

Data processing. We performed a series of filtering steps to obtain a subset of the InvaCost database containing only the costs of invasive trees. From the initial 13,553 cost entries available in the InvaCost database, we first selected only costs attributed to species or genera of plants that have a tree growth form (1044 cost entries). By adding the 38 new cost entries mentioned earlier, we obtained a set of 1082 records (Supplementary Table S1 online). Second, we removed costs which could not be converted to $ values from the original currency (n = 14), such as where official exchange rate information was unavailable from the World Bank Open Data [START_REF] Diagne | InvaCost, a public database of the economic costs of biological invasions worldwide[END_REF] . Third, we removed cost entries without both starting and ending years simultaneously provided in the database, given they provide unreliable estimates of annual cost (n = 16). However, for those entries with one starting or ending year reported (i.e., with one or the other missing, not both), we conservatively assumed the cost spanned only one year (n = 4). This option, although potentially biasing the temporal distribution of the costs (note however that these costs were excluded for the temporal analysis; see section Temporal trends), allows the consideration of the entire reported cost of invasive alien trees meeting our selection criteria, which we describe below.

As costs in InvaCost are presented over different temporal scales (i.e., different lengths of time over which the cost occurred), we standardized our dataset so that each cost entry-realized over a single year, a period of less than a year, or a cost recurring over a series of years-corresponds to a single-year estimate, which is repeated over the number of years during which the cost occurred [START_REF] Diagne | InvaCost, a public database of the economic costs of biological invasions worldwide[END_REF] . This means that the cost entries were 'expanded' without artificially inflating the aggregate cost. For example, an initial cost of $10 million over ten years would become, when expanded, ten entries of $1 million for each of the ten years. This process is crucial for examining the temporal trends in the development of costs, while minimizing temporal biases in cost reporting-which could arise from, for example, reporting a cost in a single year despite it spanning a longer period. This standardization on an annual basis was performed using the expandYearlyCosts function of the invacost R package [START_REF] Leroy | Analysing economic costs of invasive alien species with the invacost r package[END_REF][START_REF] Core | R: A language and environment for statistical computing[END_REF] . Further analyses were performed using this expanded version of the database.

Cost descriptors. We used several key descriptors that are already present in InvaCost in the form of descriptive columns categorizing each reported cost (https:// doi. org/ 10. 6084/ m9. figsh are. 12668 570). We firstly distinguished costs based on their implementation, whereby 'observed' costs were actually incurred within the invaded habitat, whereas 'potential' costs were based on predictions over time or space within or beyond the species' actual distribution area. Secondly, we distinguished costs based on the 'reliability' of the source material estimating/reporting them, whereby costs from officially pre-assessed material (e.g., peer-reviewed or official reports/documents), or material with documented, reproducible and traceable methods, were classified as of 'high' reliability, whereas all other costs were categorized as of 'low' reliability [START_REF] Leroy | Analysing economic costs of invasive alien species with the invacost r package[END_REF] . We used the 'Method_reliability' and the 'Method_reliability_refined' columns, with the latter, if provided, favored over the former in case of differing information (Supplementary Table S1 online). We first present full cost estimates, and then employ for further assessments a more focused and robust subset that includes only 'observed' and 'highly reliable' costs. Descriptors used to examine this subset of costs (called 'robust subset') included:

(i) taxonomy: the class, family, genus and species of invasive alien trees causing the cost; (ii) geographic region: the continental region and country in which the cost was incurred. The map with spacial distribution of costs of invasive trees was generated using the rnaturaleath [START_REF] Massicotte | rnaturalearth: World Map Data from Natural Earth[END_REF] and the ggplot2 R packages [START_REF] Wickham | Ggplot2: Elegant Graphics for Data Analysis 2nd edn[END_REF] , where the International Standards Organization (ISO) 3-digit alphabetic country codes were assigned to InvaCost data using the countrycode R package 73 ; (iii) environment_IAS: the habitat where the invasive alien trees were identified (i.e., terrestrial, or semiaquatic); (iv) impacted sector: the activity, societal or market sector that was monetarily impacted by the invasive trees, which includes ' Agriculture' , ' Authorities-Stakeholders' (governmental departments and/or official organizations such as conservation agencies, forest departments, associations; we note that this definition includes both authorities and stakeholders separately in a broad sense), 'Public and social welfare'; 'Environment' and 'Fishery'; (v) type of cost: 'Damage' (i.e., costs of repairing damage, loss of resources), 'Management' (i.e., expenses on surveillance, prevention, control or eradication, etc.) and 'Mixed' , (category used when reported costs were not easily distinguished between damage and management costs) and; (vi) type of management cost: 'pre-invasion' (i.e., monetary investments for preventing successful invasions in an area-including quarantine or border inspection, risk analyses, biosecurity management, etc.), 'post-invasion' (i.e., money spent for managing invasions in invaded areas-including control, eradication, containment), 'knowledge funding' (i.e., money allocated to all actions and operations that could be of interest at all steps of management at pre-and post-invasion stages-including administration, communication, education, research, etc.) and 'mixed' (i.e., when costs include at least two of the previous categories and without possibility to disentangle the specific proportion of both). Detailed information on all descriptive variables can be found in the online repository of the InvaCost database (https:// doi. org/ 10. 6084/ m9. figsh are. 12668 570).

Temporal trends. We examined the temporal development of invasion costs between 1960 and 2020, calculating annual costs [START_REF] Leroy | Analysing economic costs of invasive alien species with the invacost r package[END_REF] . We employed the invacost R package through the summarizeCosts function. As explained above (Data processing), this temporal analysis removed entries for which the temporal duration was

Uses of alien trees. For those invasive alien trees with highly reliable costs we obtained their uses or reasons for the introduction from the Invasive Species Compendium of Centre for Agriculture and Biosciences International (CABI) database, Richardson & Rejmanek (2011) and the World Economic Plant database (WEP, National Plant Germplasm System GRIN-GLOBAL; https:// npgsw eb. ars-grin. gov/ gring lobal/ taxon/ taxon omyse arche co, Accessed 13 Feb 2022). We followed the classification of uses of invasive alien trees determined by Richardson and Rejmanek (2011): commercial forestry; high quality furniture/wood; horticulture (ornamental, including coverage); agroforestry (including fodder), firewood and charcoal; food (including spices and medicines); stabilisation, erosion control and fertility improvement; and ' others' (including shade, biofuels and rubber). We evaluated the relationship between categories of uses of invasive alien trees and the costs of the invasive alien trees attributed to these uses. Thereby, we also examined whether species-specific costs were influenced by the numbers of distinct uses among individual invasive trees. For single species with multiple uses, we took the relative frequency of each use across all previously filtered InvaCost records for trees and used these relative frequencies to apportion each species' total costs into each use. For instance, if a species had 2 uses (use 1 and use 2) and the frequency of use 1 was 20%, and use 2 was 10%, the total cost X was considered as two thirds of use 1 and one third of use 2.

Figure 1 .

 1 Figure 1. Spatial distribution of recorded costs of invasive trees. The map shows with a color categorical gradient the countries with the highest (black) to lowest (cream) cost recorded ('observed' and 'highly reliable' costs; 2017 US Dollars) of invasive trees. Countries without observed cost reports are in white. The map also indicates the number of references reporting costs of invasive trees by country with the green node size.

Figure 2 .

 2 Figure 2. Costliest families and genera. Top ten costliest families of invasive trees and the respective costliest genera of the top five families considering highly reliable, observed costs records (in 2017 US$ billions). Different colors indicate different families and shades distinguish genera.

Figure 3 .

 3 Figure 3. Sectors affected and type of cost. Total costs (highly reliable and observed) of invasive alien trees according to (a) impacted sector and (b) type of cost.

Figure 4 .

 4 Figure 4. Uses of invasive trees with cost records. Tree height shows the number of invasive tree species for each category of use and the number on top shows the total cost incurred (highly reliable and observed), also indicated by shades of green with darker green representing higher costs (see text for details).

Table 1 .

 1 Top ten costliest invasive alien trees considering highly reliable, observed costs records and their expanded database entry numbers.

	Species

Cost ($ millions) Database entries (n) Scientific name Common name Family

	Acacia mearnsii	Black wattle	Fabaceae	2,175	107
	Elaeis guineensis	African oil palm	Araceae	1,356	18
	Melia azedarach	Chinaberry	Meliaceae	150	50
	Cereus jamacaru	Queen of the night	Cactaceae	85	37
	Melaleuca quinquenervia	Paperbark tree	Myrtaceae	78	23
	Baccharis halimifolia	Groundseltree	Asteraceae	23	90
	Schinus terebinthifolia	Brazilian pepper tree Anacardiaceae 16	9
	Solanum mauritianum	Tobacco tree	Solanaceae	14	51
	Prunus serotina	Black cherry	Rosaceae	14	31
	Acacia saligna	Coojong	Fabaceae	13	21
	Total			3924	437

Scientific Reports | (2023) 13:8945 | https://doi.org/10.1038/s41598-023-35802-4

Scientific Reports | (2023) 13:8945 | https://doi.org/10.1038/s41598-023-35802-4

Acknowledgements R.N.C. is funded by an Early Career Fellowship from the Leverhulme Trust (ECF-2021-001). G.H. postdoctoral research is supported by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -Brasil (Capes) -Finance code 001 and Alexander von Humboldt Foundation. This study was conducted following a workshop funded by the AXA Research Fund Chair of Invasion Biology of University Paris Saclay and is part of the Alien-Scenarios project funded by Biodiversa and Belmont-Forum call 2018 on biodiversity scenarios (BMBF/PT DLR 01LC1807C). C.A.D. was funded by AlienScenarios and E.A. was funded by the AXA Research Fund Chair of Invasion Biology of University Paris Saclay.

Funding

Open Access funding enabled and organized by Projekt DEAL.

Data availability

All data generated and analyzed during this study are included in this published article (and its Supplementary Information files).

Author contributions

R.D.F., F.C. and M.A.N. conceptualized the research; R.D.F. took the lead in collecting and curating data with inputs from E.A. and C.A.D.; P.J.H. conducted data analysis; R.D.F. led the writing of the first draft of the manuscript with inputs of R.N.C. and P.J.H. All authors provided critical feedback and helped shape the research, analysis and manuscript.

Competing interests

The authors declare no competing interests.


Anna J Turbelin
email: anna.turbelin@universite-paris-saclay.fr

Ross N Cuthbert

Franz Essl

Phillip J Haubrock

Anthony Ricciardi

Franck Courchamp
email: franck.courchamp@universite-paris-saclay.fr

Biological invasions are as costly as natural hazards

Keywords:

Damage costs from biological inva- sions and natural hazards are of similar magnitude.

• Global biological invasion costs

Introduction

Biological invasions are a growing component of global environmental change (e.g. [START_REF] Pyšek | Scientists' warning on invasive alien species[END_REF]. A subset of alien species -those that are invasive -have emerged as a major driver of biodiversity loss (e.g., [START_REF] Bellard | Alien species as a driver of recent extinctions[END_REF] and gen- erate massive and rising economic costs [START_REF] Diagne | High and rising economic costs of biological invasions worldwide[END_REF]. Invasive alien species (henceforth 'invasive species') are defined as species present in a region as a result of human actions with harmful impacts to societies and the environment, such as reducing crop yields, damaging critical infrastructures, and disrupting ecosystem service provisioning [START_REF] Pyšek | Scientists' warning on invasive alien species[END_REF] (see Fig. 1). Biological invasions also exacerbate human health risks and cause hundreds to thousands of human deaths annually, through disease emergence and spread, lethal bites and stings, or complicated allergies (e.g., [START_REF] Mazza | Biological invaders are threats to human health: an overview[END_REF]Vilà et al., 2021). If emerging pathogenic microorganisms were to be considered as invasive species [START_REF] Nu Ñez | Invasion science and the global spread of SARS-CoV-2[END_REF][START_REF] Hulme | The Epidemiological Framework for Biological Invasions (EFBI): an interdisciplinary foundation for the assessment of biosecurity threats[END_REF][START_REF] Hulme | One biosecurity: a unified concept to integrate human, animal, plant, and environmental health[END_REF], then the annual human mortality toll of biological invasions would be far greater (HIV alone, spread from apes in Africa, was responsible for ∼680 thousand deaths in 2020 worldwide, https://www.who.int/data/gho/data/themes/hiv-aids).

Surprisingly, given their huge environmental, health and socioeconomic impacts, awareness of the severity of biological invasions remains low [START_REF] Courchamp | Invasion biology: specific problems and possible solutions[END_REF]. Investments in the management of invasions have been vastly underfunded and delayed, causing trillion-dollar impacts that could have been avoided [START_REF] Cuthbert | Biological invasion costs reveal insufficient proactive management worldwide[END_REF][START_REF] Ahmed | Managing biological invasions: the cost of inaction[END_REF]. Management of biological invasions has been shown to be rarely proactive and often delayed, with most countries focusing on costly post-invasion measures which are rarely successful. The underfunding towards biological invasions is also highlighted by the total lack of reported investments in management in many countries of the world [START_REF] Cuthbert | Biological invasion costs reveal insufficient proactive management worldwide[END_REF]. Therefore, even if damages from biological invasions have been shown to be high, societal concern has been insufficient to warrant adequate management investment by decision makers.

This lack of awareness and concern is all the more remarkable, when natural hazards such as earthquakes, floods and wildfires have received substantial societal attention and investment for mitigation or adaptation. Indeed, biological invasions and natu-ral hazards are comparable phenomena, with notable similarities such as their dynamics of occurrence and impact, and difficulty of prediction and control [START_REF] Ricciardi | Should biological invasions be managed as natural disasters?[END_REF]. Although nations invest in preparedness and emergency response plans for extreme (and typically rare) natural hazards, similar precautions for invasive species are not comprehensively applied by most nations, possibly because the socioeconomic consequences of natural hazards are better understood by the public than those of invasions. Consequently, more systematic accounting is needed to accurately prioritise biological invasions to protect human assets and human lives. In the absence of actions, even after the publication of substantial economic costs to societies [now reaching $2000 bn (United States dollars) when considering damage losses and management costs between 1970-2020] [START_REF] Diagne | High and rising economic costs of biological invasions worldwide[END_REF], there is a growing urgency to highlight the risks of ignoring biological invasions in policies, legal frameworks and decision-making processes globally. Monetary value is a metric allowing for standardised, quantitative comparison, and is understandable by a wide audience. Therefore, contextualising the size of economic costs from biological invasions relative to that of natural hazards could help to raise awareness and political leverage.

The spatial and temporal scales over which natural hazards impact the natural environment cover many orders of magnitude, ranging from landscape to large (e.g. continental) scales, and from seconds to millennia. Some natural hazards, such as avalanches or floods, can create large impacts in seconds (including direct human deaths), whilst others such as drought are more gradual in their manifestation. Impacts of invasions are likewise complex and may fully manifest only decades after introduction when invaders are already well-established [START_REF] Pyšek | Scientists' warning on invasive alien species[END_REF][START_REF] Spear | The invasion ecology of sleeper populations: prevalence, persistence, and abrupt shifts[END_REF]. The concept of invasion debt means that currently impactful invaders reflect legacies of socioeconomic activities several decades ago, whereas impacts from recent aliens arriving from current pathways may have not yet been realised [START_REF] Essl | Socioeconomic legacy yields an invasion debt[END_REF]. In this regard, biological invasions may typically be considered as a slow-onset hazard, as they emerge gradually over time -but their impacts are cumulative and profound, including species extinctions, massive costs and even human deaths [START_REF] Pyšek | Scientists' warning on invasive alien species[END_REF][START_REF] Diagne | High and rising economic costs of biological invasions worldwide[END_REF]Mazza and Tricarico, 2018). These differences in speed and pattern of manifestation of hazards influence how humans perceive and respond to them. Despite comparable societal and ecological impacts [START_REF] Ricciardi | Should biological invasions be managed as natural disasters?[END_REF], sudden-onset acute hazards tend to attract more attention than slow-emerging chronic ones [START_REF] Staupe-Delgado | Progress, traditions and future directions in research on disasters involving slow-onset hazards[END_REF]. Accordingly, slow-onset hazards may dampen societal and political awareness of risk and impede rationale to invest in long-term mitigation. Similarly, risk awareness may be influenced by the association of human fatalities with natural hazards and our bias in overestimating rare causes of death, while simultaneously underestimating common ones [START_REF] Lichtenstein | Judged frequency of lethal events[END_REF]. Although both natural hazards and biological invasions may cause human fatalities (Mazza and Tricarico, 2018), deaths caused by invasions (e.g., invasive pathogen/parasite vectors or allergic reactions) are often less direct and rarely attributed solely to invaders.

Here, we quantify and compare the costs of biological invasions and natural hazards at three scales: (i) globally, (ii) regionally and (iii) nationally (i.e., the USA as a case study). At all these scales, our objectives were to: (i) compare the total costs of biological invasions to natural hazards of societal concern; and (ii) examine the temporal trends among biological invasion and natural hazard costs to compare their rates of change.

Materials and methods

Invasive species cost data collection and filtering

We compared biological invasion costs to natural hazards at the global scale, the regional scale and at a representative national scale with high data availability (i.e., the USA). To quantify economic losses generated by the impacts of biological invasions, we used data from the InvaCost database version 4.1 -the most up-to-date, comprehensive, standardised and robust data compilation and description of economic cost estimates associated with invasive species worldwide (https://doi.org/10.6084/m9.figshare.12668570 [START_REF] Diagne | INVACOST: a public database of the global economic costs of biological invasions[END_REF] -downloaded using the data() function from the invacost R package version 1.1-4 (R Core Team 2020) [START_REF] Leroy | invacost: invacost database with methods to analyse invasion costs[END_REF]. We filtered the database to only include costs that were actually incurred (classified as observed in the "Implementation" field) and labelled as highly reliable ("Method reliability" field). Because cost assessments for natural hazards generally only account for direct costs, therefore omitting indirect, business interruption, intangible, and risk mitigation costs [START_REF] Kreibich | Costing natural hazards[END_REF], we decided to only include damage costs ("Type of cost merged" field) -economic losses resulting from direct or indirect impacts of invasive species [START_REF] Diagne | INVACOST: a public database of the global economic costs of biological invasions[END_REF] -and explicitly exclude post-invasion management or mixed costs to avoid inflating costs attributed to biological invasions. We also constrained the data to damage costs because management spending or investment reflects a human decision making process that may lead to cost unevenness (due to e.g., government policy differences), whereas damage costs are a more standardised measure of actual, realised economic impact. The filtered dataset is available in Supplementary Material Data S1.

Highly reliable observed damage costs for the USA from invasive species were obtained by filtering InvaCost 4.1 data as described above and retaining entries attributed to "United States of America" in the "Official country" field. We adapted the TDWG World Geographic Scheme for Recording Plant Distributions Standard (TDWG, 2001) to reclassify InvaCost field "Geographic region" and obtain the breakdown of highly reliable observed damage costs by continental regions. The list of countries and matching regions is available in Supplementary Material Data S2.

As costs may be recorded as a single or multi-year estimate, to obtain annualised costs we expanded the database using the expandYearlyCosts() function from the invacost R package version 1.1-4 (R Core Team 2020) [START_REF] Leroy | invacost: invacost database with methods to analyse invasion costs[END_REF] (see [START_REF] Cuthbert | Biological invasion costs reveal insufficient proactive management worldwide[END_REF].

Natural hazards cost data collection and filtering

Global and regional cost data for natural hazards are available from EM-DAT, CRED/UCLouvain, Brussels, Belgium international disasters database (www.emdat.be) -the global database on natural and technological disasters, which includes geographical, temporal, human and economic data on the occurrence and effects of more than 21,000 disasters in the world at country level, from 1900 to present. Only natural hazard events which fulfil at least one of the defined criteria are reported. These criteria include: 10 or more people dead; 100 or more people affected (e.g. injured, homeless); country of where the event occurs declares a state of emergency or an international assistance appeal. Data were downloaded on 06 April 2022 [query id x0lcUA], using the following filters: Disaster Classification: Natural; Location: Asia, Africa, Americas, Europe, Oceania; and from 1980 to 2019. As for InvaCost data, we adapted the TDWG World Geographic Scheme for Recording Plant Distributions Standard (TDWG, 2001) to reclassify the EM-DAT field "Continent" (Supplementary Material Data S3).

Natural hazard cost data for the USA were obtained via Billion-Dollar Weather and Climate Disasters from NOAA National Centers for Environmental Information (NCEI) (2022). These data were downloaded on 06 April 2022 (Supplementary material data S4). We added the USA as a national case study because of its relative data completeness to see if we obtained similar results when using a national database with different inclusion criteria of events. Weather and climate events reported in the NOAA NCEI dataset are those with direct cost (incl. physical damage to residential, commercial and government/municipal buildings, material assets within a building, time element losses, vehicles, boats, offshore energy platforms, public infrastructure and agricultural assets) equal to or above $1bn USD -which account for more than 80% of the damage from all recorded weather and climate events.

Standardizing cost values to USD 2020

To compare costs across years and between databases, we standardised all cost values to US Dollars (USD) 2020 using the consumer price index (CPI) (2010 = 100) data, which are available from the World Bank Open Data (https://data.worldbank.org/indicator/FP.CPI.TOTL). These data were downloaded using the 'wbstats' R package (version 1.0.4) [START_REF] Piburn | wbstats: Programmatic Access to the World Bank API[END_REF] on December 14, 2022. InvaCost cost values are expressed in USD 2017 -the methodology used to convert raw costs in local currencies for a given year to USD 2017 is described in [START_REF] Diagne | INVACOST: a public database of the global economic costs of biological invasions[END_REF]. We used the function adjustInflation() [START_REF] Cuthbert | Biological invasion costs reveal insufficient proactive management worldwide[END_REF] to adjust the 2017 USD cost estimate values to 2020 USD values. The function draws the 2020 CPI value (118.6905016) from the World Bank Open Data file to convert 2017 USD costs to 2020 USD costs using the following formula:

Cost(2020USD) = (1 + ((CPI2020 -CPI2017)/CPI2017)) × Cost(2017USD)
Natural hazard costs from the EM-DAT database are expressed in thousands of USD (i) in the value of the year of occurrence and (ii) adjusted for inflation to the current USD value -at the time of our analysis it was USD 2020. We converted the costs from thousands Weather and climate events reported in the NOAA NCEI dataset are those with direct cost (incl. physical damage to residential, commercial and government/municipal buildings, material assets within a building, time element losses, vehicles, boats, offshore energy platforms, public infrastructure and agricultural assets) equal to or above $1bn USD. Only observed ("Implementation" field) damage ("Type of cost merged" field) costs classified as highly reliable in InvaCost ("Method reliability" field) are included in this figure . USA damage costs were obtained by retaining entries attributed to "United States of America" in the "Official country" field of InvaCost 4.1.

of USD to be expressed in USD by multiplying the values by 1000. As the current value adjusted for inflation will change over time, we converted the unadjusted values using the adjustInflation() function [START_REF] Cuthbert | Biological invasion costs reveal insufficient proactive management worldwide[END_REF], which uses the following equation:

Cost(2020USD) = (1 + ((CPI 2020 -CPI yrt )/CPI yrt )) × Cost
with CPI yrt the CPI of the year of the event occurrence. We followed the same methodology to convert unadjusted for inflation costs of US billion-dollar weather and climate disasters provided by the NOAA NCEI.

Analyses

All analyses were conducted in R and figures were formatted in Adobe Illustrator. The R script and data are available in Supplementary Materials and/or on GitHub [START_REF] Cuthbert | Biological invasion costs reveal insufficient proactive management worldwide[END_REF]. As the aim of our study is to compare the magnitude of global economic losses from biological invasions to that of natural hazards, we calculated the overall costs by summing all cost estimates provided in the expanded dataset -see Supplementary Material Data S1. The total costs for natural hazards were obtained by summing costs in USD 2020 of all recorded events separately for the global and USA datasets.

The rate of change (ROC) between periods 1980-1999 and 2000-2019 was calculated using the following equation: (Fig. 2a), with a 702 % increase in reported losses from 1980 to 1999 to 2000-2019 (Figs. 2b and3). When compared to economic losses and damage costs from natural disasters reported in EM-DAT (2022) over the same period, biological invasions were less costly than storms ($1,913.6 bn), but exceeded earthquakes ($1,139.4 bn), floods ($1,120.2 bn) and all other hazards. Similarly, when comparing reported economic losses from biological invasions in the United States of America (USA) to the cost of disaster events reported in National Centers for Environmental Information National Oceanic and Atmospheric Administration (NOAA NCEI, 2022) between 1980-2019, biological invasions damage costs ($467.5 bn) were lower than costs from storms ($1,202.2 bn), but exceeded that of droughts ($247.7 bn), floods ($143.5 bn), wildfires ($83.9 bn) and freezes ($28.3 bn) (Fig. 2c). Costs recorded in NOAA NCEI account for more than 80% of the damage from all recorded weather and climate events. Nonetheless, if increasing the costs of disaster events provided up to 100% -with biological invasion costs remaining the same -then biological invasions would still rank second. The percentage increase in biological invasions damage costs in the USA was nevertheless more than twice that of all natural hazards (Figs. 2d and3). The ranking of biological invasions compared to natural hazards was, however, variable among continental regions, ranging from the costliest in Oceania and Pacific, to the fourth costliest in Europe and Temperate Asia (Figs. 4, S1 and S2).

Discussion

Our results suggest that damage costs from biological invasions and natural hazards are of similar magnitude, each reflecting an enormous and increasing burden on societies. There is inherent uncertainty associated with the position of economic costs from biological invasions compared to that of natural hazards, globally, regionally or within a given nation (exemplified in the USA). Cost assessments for natural hazards typically only account for direct costs and these remain under-recorded [START_REF] Mcglade | Global Assessment Report on Disaster Risk Reduction[END_REF]. Additionally, global or national data on natural hazards costs are not always available for all impacts, but rather for selected hazards that meet a certain impact threshold (see Fig. 2 legend). Likewise, documenting the cost of biological invasions is complex and fragmentary. For example, only about 5% of known invasive species have costs reported in the literature and documented in InvaCost (e.g. 713 of 13,867 invaders reported globally) [START_REF] Cuthbert | Global economic costs of aquatic invasive alien species[END_REF]. Even for those species, their costs are typically very conservative due to pervasive geographic and sectoral knowledge gaps [START_REF] Angulo | Non-English languages enrich scientific knowledge: the example of economic costs of biological invasions[END_REF]. In addition, whereas it can be assumed that natural hazard costs include some mitigation expenditures, our comparison is only with damage costs of biological invasions, thus explicitly excluding post-invasion management or mixed costs (an additional $339 bn between 1980-2019). Moreover, as for natural hazards, costs are most often lacking monetary valuation of non-market value losses, indirect impacts or impacts on ecosystem services [START_REF] Diagne | INVACOST: a public database of the global economic costs of biological invasions[END_REF]. Consequently, economic costs of biological invasions are also severely underestimated. Despite a likely cost underestimation, both global databases -InvaCost and EM-DAT -can be considered a baseline for global and regional costs of biological invasions and natural hazards, respectively, due to their robust systematic approach in collecting cost information and their 'living' nature, whereby the data are continuously reviewed. Nonetheless, costs should be considered as minimum estimates, and seen in terms of order of magnitude rather than as precise values.

Biological invasions are known to be a major driver of biodiversity loss and ecosystem service disruption (IPBES, 2019). Importantly, biological invasions can interact with multiple natural hazards to exacerbate impacts. Indeed, biological invasions can worsen flood, wildfire and drought risks by modifying ecosystem structure and function [e.g. by damaging river banks (burrowing animals), intensifying fire regimes (woody plants) and guzzling water/choking waterways (aquatic plants, see Fig. 1d); (Turbelin, 2020)]. Reciprocally, hazards associated with climate change (e.g. wildfires, droughts, floods) can promote biological invasions by disturbing or transforming landscapes, thereby changing environmental conditions and creating empty niches which are readily invaded [START_REF] Diez | Will extreme climatic events facilitate biological invasions? Front[END_REF]. Although both natural hazards and biological invasions are difficult to predict and control, the humanmediated movement of species, unlike the occurrence of many natural hazards, could in many cases be slowed or prevented. Whereas damages may be expectedly costlier than efficient management spending due to rising economic, ecological and health impacts, management costs of biological invasions have remained one to two orders of magnitude below their damages [START_REF] Cuthbert | Biological invasion costs reveal insufficient proactive management worldwide[END_REF]. Worse, of this management expenditure, a very small share has been invested proactively (3%) on measures such as prevention that mitigate future invasion impacts [START_REF] Cuthbert | Biological invasion costs reveal insufficient proactive management worldwide[END_REF]. Whilst extreme natural hazards (earthquakes, wildfires, hurricanes, etc.) have a highly skewed frequency-magnitude distribution (as do biological invasions; [START_REF] Ricciardi | Should biological invasions be managed as natural disasters?[END_REF], it is expected that affluent societies will invest in the prevention of these rare events, because their occurrence carries unacceptable costs. The same precautionary approach (investment in vulnerability reduction, rapid response, and risk assessment) should be applied to biological invasions.

Invasion impacts are often irrevocable and insidious, making this aspect of global change a severe concern for humanity that should be of greater focus in policy agendas. Perhaps even more so than for natural hazards, biological invasions require transboundary collaboration, including the need for stronger international legal frameworks to limit new invasive species introductions and spread. While regional variability in cost reporting and incurrence from biological invasions is well known [START_REF] Diagne | High and rising economic costs of biological invasions worldwide[END_REF], costs of biological invasions remained comparable to natural hazards across all regions globally in terms of their order of magnitude. Moreover, across all regions, with the single exception of Temperate Asia, the costs of biological invasions have been rising at a much faster rate than those of natural hazards. This further underscores the urgent need for internationally-coordinated actions to address the biological invasion problem. Decision makers should prioritise proactive investments such as prevention and rapid eradications to avoid delayed, long-term control measures and damages [START_REF] Cuthbert | Biological invasion costs reveal insufficient proactive management worldwide[END_REF]. In the last century, biological invasions and their impacts have increased strongly worldwide (Fig. 3), and still show no sign of saturation [START_REF] Seebens | No saturation in the accumulation of alien species worldwide[END_REF], while climate and global land use changes raise concerns of renewed acceleration [START_REF] Bellard | Will climate change promote future invasions?[END_REF][START_REF] Bellard | Insights from modeling studies on how climate change affects invasive alien species geography[END_REF][START_REF] Chytr Ý | Projecting trends in plant invasions in Europe under different scenarios of future land-use change[END_REF]. With monetary impacts from biological invasions having already increased at a higher rate than other top hazards over the last 40 years, it is plausible that -without adequate measures implementedinvasive species will remain comparable to the most impactful natural hazards in coming decades. Our results support the view that the prevention of biological invasions merits similar precautionary investments as those applied to extreme natural hazards [START_REF] Ricciardi | Should biological invasions be managed as natural disasters?[END_REF].

Fig. 1 .

 1 Fig. 1. Pictures of natural hazards impacts and invasive alien species. A) Wildfire, South Africa, 2014 B) Flood, Bingley UK, 2015 C) Earthquake, 2021 and D) Invasive water hyacinth clogging waterways (Eichhornia crassipes) Jatiluhur, Purwakarta Regency, West Java, Indonesia, 2021. Pictures by A) Anna Turbelin, B) Chris Gallagher on Unsplash, C) Dave Goudreau on Unsplash, and D) Eka P. Amdela on Unsplash.

Fig. 2 .

 2 Fig. 2. Raw damage cost and percentage change of natural hazards and biological invasions for the period 1980-2019 for a), b) the world and c), d) the United States of America (USA). Damage costs of natural disasters in the world, the USA, and biological invasions are from the International Disaster Database EM-DAT (www.emdat.be), the National Centers for Environmental Information National Oceanic and Atmospheric Administration (NOAA NCEI; www.ncdc.noaa.gov), and InvaCost 4.1 (www.invacost.fr), respectively. Costs from emerging diseases are not included in biological invasions. Costs in EM-DAT are values of all damages and economic losses directly or indirectly related to the disaster; only natural hazard events which fulfil at least one of the defined criteria are reported (e.g. 10 or more people dead; 100 or more people affected). Weather and climate events reported in the NOAA NCEI dataset are those with direct cost (incl. physical damage to residential, commercial and government/municipal buildings, material assets within a building, time element losses, vehicles, boats, offshore energy platforms, public infrastructure and agricultural assets) equal to or above $1bn USD. Only observed ("Implementation" field) damage ("Type of cost merged" field) costs classified as highly reliable in InvaCost ("Method reliability" field) are included in this figure. USA damage costs were obtained by retaining entries attributed to "United States of America" in the "Official country" field of InvaCost 4.1.

Fig. 3 .

 3 Fig. 3. Cumulated annual damage cost of natural hazards and biological invasions for the period 1980-2019 a) globally and b) the United States of America (USA). Information on the data and sources is the same as for Fig. 2.

Fig. 4 .

 4 Fig. 4. Damage cost of natural hazards and biological invasions for the period 1980-2019 by geographical region. Damage costs of natural disasters and biological invasions are from the International Disaster Database EM-DAT (www.emdat.be) and InvaCost 4.1 (www.invacost.fr), respectively. All other information on the data and sources is the same as for Fig. 2.

Acknowledgments

We thank Christophe Diagne for his helpful comments. We further thank the Editor, Jean Paul Metzger, the associate Editor and the two anonymous reviewers for their helpful comments.

Funding

This work was supported by the AXA Research Fund Chair of Invasion Biology of University Paris Saclay (AJT), BiodivERsA Belmont-Forum call 2018 on biodiversity scenarios (FC, FE), French National Research Agency [ANR-14-CE02-0021] (FC), BNP-Paribas Foundation Climate Initiative (FC), Leverhulme Trust [ECF-2021-001] (RNC), and the Natural Sciences and Engineering Research Council of Canada (AR).

Data accessibility statement

Data used for this study are freely available on github and online.

Competing interests

Authors declare that they have no competing interests.

CRediT authorship contribution statement

Declaration of Competing Interest

The authors report no declarations of interest.

ARTICLE IN PRESS


Anne Bationo Tillon

Françoise Decortis
email: françoise.decortis@univ-paris8.fr

Using image in the narrative activity

Keywords: Experimentation, Human Factors Narrative activity, images

In this paper, we propose to discuss the different status and role of images in narrative activities. How the image could mediate the relationship of the narrator to his/her experience? How can children use the image in their narrative activity? First, we expose our theoretical framework. Then through two studies, we examine the status and roles of images in different contexts of production: photographs produced with low technology and short movie created with a mobile phone.

INTRODUCTION

While most narrative activities, especially in school, are focused on written and verbal productions, teachers also know that stories can be told in many media, including images like drawings, videos, photography [START_REF] Ackermann | Strumenti narrativi, scrittura dialogica[END_REF] [START_REF] Lentini | Space and places : when interacting with and in physical space becomes a meaningful experience[END_REF]. Children "speak in a hundred languages" [START_REF] Malaguzzi | I cento linguaggi dei bambini: Narrativa del possibile. Proposte di bambini delle scuole dell'infanzia di Reggio Emilia[END_REF]. Initiation to narrative composition provides children with the means to express themselves, and to convey their intentions successfully. One of the criteria for evaluating of these skills is the capacity to combine and prioritize their experience. Images creating during experience produce crystallization, a sort of externalization, an outsourcing of a work even minor, which produces a pride to the one who realized it [START_REF] Bruner | L'éducation entrée dans la culture[END_REF]. This material can be used in narrative activity.

THEORETICAL FRAMEWORK

By narrative activity, we mean the activity by which the child gives meaning and reports his/her experience in a creative way. This perspective refers to stories or narratives produced and told by narrators, in this particular case by children but, not only, by using diverse means and resources such as language, sounds, music, games, scene played by children. By contrast with [START_REF] Fayol | Le récit et sa construction. Une approche de psychologie cognitive[END_REF], our attention goes thus towards the production of stories and narrative rather than towards their understanding. Children can collectively create these stories. They can also be produced collectively by groups of different generations (children and adults). In most of the situations, the narrators use multiple languages: drawings, photos, music, etc. The reality, the environment, supply materials which will be used by the narrators in their production. Finally, we believe that creativity can be an essential constituent of the construction of the narrative activity. Our perspective is therefore grounded in a sociocultural perspective, which implies that through narrative children learn to give a meaning to their experiences [START_REF] Bruner | L'éducation entrée dans la culture[END_REF], [START_REF] Vygotsky | Imagination and creativity in childhood[END_REF]. Children use stories to represent the world to themselves as well as to each other [START_REF] Nicolopoulou | Children and narratives: toward an interpretive and sociocultural approach[END_REF]. In constructing their stories, children draw on images and resources present in their cultural environment, which shape their imagination and sensibility in profound and subtle ways [START_REF] Nicolopoulou | Children and narratives: toward an interpretive and sociocultural approach[END_REF], [START_REF] Vygotsky | Imagination and creativity in childhood[END_REF]. Thus, the understanding of these processes requires relating the child narrative activity to the sociocultural context of daily interactions, communities and the cultural world. Vygotsky [START_REF] Vygotsky | Imagination and creativity in childhood[END_REF] considers the centrality of the psychological processes of creativity and imagination in the educational process. For Vygotsky, imagination is present in all aspects of the cultural life and makes the artistic, scientific and technical creativity possible. Reality and imagination are correlated according to Vygotsky by at least four relations: 1) Imagination is built starting from reality. The richer the experience, the more the individual will have materials to build his imagination. 2) The social practices and experiences exchange with our pairs. 3) Emotions, the feelings influence imagination and vice versa. 4) The crystallization of imagination in external and shared objects. Moreover, Vygotsky identifies the mechanisms of imagination and creativity: the experience and the reelaboration of experience through disassociation, association and mutation. In a previous research [START_REF] Decortis | Mediating effects of active distributed instruments on narrative activities[END_REF], we found empirical evidence that the cycle of creative imagination proposed by Vygotsky as a psychological process could be used to inform the design of narrative technology-enhanced learning. The model, NAMC++, that emerges from this perspective has four phases namely, exploration, inspiration, production and sharing (figure 1). It describes how the individual experiences the external world, elaborates the impressions received, assembles them in a novel way and shares this production with others [START_REF] Decortis | Mediating effects of active distributed instruments on narrative activities[END_REF].

Exploration consists of the interactions with the real world, which can be either direct or mediated by social relations. The sensory experiences constitute the starting point for the theme and for the ideas, what the child has seen, heard, touched or encountered in various experiences (museum, forest) or even in the classroom with the support of objects and people. At this stage, the child uses instruments appropriate for exploration (e.g. microscope, points of view, etc.) and handles various materials (e.g. earth, shells, sand, photos, objects, etc.).

Inspiration is a phase of reflection and analysis on the experience during the exploration. The child is encouraged to think about the previous experience, discuss it and sort out the elements they gathered. Individual writing, drawing or group discussion usually supports this phase.

Production corresponds to the recombination of the elements dissociated and transformed during the previous phase. It is the moment where children, based on selections and choices of elements, produce new content usually through a great variety of media. During this phase, the children mainly use their notebooks, pens and pencils for illustrations, cardboards, puppets, posters and bricolage sets.

Sharing is the phase in which children's externalised productions start to exist in their social world. Children present the result of their production and verify the effects of this production on the others (e.g., children, teachers, parents). Sharing can be supported by instruments such as notebook or it is a full-scale performance of groups of children or of the whole class. Our objectives here are to question NAM++ model. Indeed, the model appears to us as being useful at the same time to understand the underlying instrumental mediations in the narrative activity, to think of instruments and to conceive these instruments. We examine the influence of two very different technologies of image creation to understand how children could use them in their narrative activity. Even if the sample population of our studies were not uniquely children, we present the principal results of each study in order to compare the status and roles of images in narrative activity.

CASE STUDIES

We draw from 2 case studies to shed light into narrative competences and creative contributions to create images, and to gauge the potential of different technologies to support narrators' expressivity in informal, community bases setting. Case studies are presented in 2 vignettes: PINHOLES, and video mobile-all of which blend traditional and digital media. We assert that the context in which images are produced (situations, tools, etc) is important and influence the characteristics of images. And this distinction is important teachers and pupils engaged in narrative and creative activity can use images in different way at school.

Vignette 1 -Pinholes

This project reunites participants from different generations and socio-cultural backgrounds where children, teenagers, adults and elders are invited to individually and collectively discover and tell stories about their quarter, neighbourhood, habits, living space, cultural differences by producing pinhole images and narratives [START_REF] Lentini | Space and places : when interacting with and in physical space becomes a meaningful experience[END_REF]. Different steps compose the joint creative activities. Participants are invited to build their camera, observe their environments, explore their ideas, shoot, develop the photographs and create narratives on the issue of Territory.

What kind of technology?

The pinhole is a low technology. Pinholes are rudimentary camera following the principle of a camera obscura: small boxes pierced by a very little hole that allows light to come inside, they capture the reality just like the eyes do. On the surface that is opposed to the hole, an inverted image of the subject is formed and captured by a photo-sensible paper (such as photographic paper). It is an "open" artefact : participants are physically involved in the different steps of the process leading from the camera to the photography. Each step, to be successfully completed, implies a reflection before to act.

Methodology

The case study involved an analysis of four workshops with a total of 62 participants. Data collection relied on observations and interviews with participants and animators.

Description of the narrative activity with model NAM++

Exploration. The exploration phase takes place from the building of the pinhole to the first picture obtained. The participants discover their environment but also how the pinhole mediates their relationship to the environment. They appreciate its physical and sensorial properties and discover their surroundings. They figure out how the things they see can be transformed by the action of taking picture: they take a castle in picture but the photo obtained look like a firefly.

Inspiration. Thanks to their first picture, they can reflect on, and share with other, the feelings and meanings related to this first experience. As participants explained, it is like if they had "new eyeglasses". The dissociation is mediated and facilitated by objects. The image, the photograph obtained, and the "ceremony" which surrounds the discovery of the image (developing photos in the darkroom, to put the photograph to be dried, act as many moments of exchanges with the others) makes it possible to reconsider the feelings, the impressions related to the use of the pinhole.

Production The production phase really arises through the iteration of the loop: Through multiple experiences of the environment and of the pictures obtained, they plan their production. They choose to use the pinhole differently (e.g. superposing images), and to express particular things through their photo (e.g. how I feel today). The activity provides opportunities for the participants to express themselves and give value to their opinions and feelings. Moreover, we have observed that the shooting step could lead to rich interactions and collaborative behaviours.

Sharing. The moments when the photos are shared represent great opportunities to interact. Participants discuss about their respective pictures, give their opinion, congratulate each other, and ask questions about how the picture was taken, where it was taken. It favours the improvement of the pinhole camera's use and helps each participant to increase his/her knowledge of the pinhole technique. The pinhole, as an externalizable tool [START_REF] Fayol | Le récit et sa construction. Une approche de psychologie cognitive[END_REF], favours learning because it provides external results that can be shared and discussed among the participants.

Vignette 2 -Video phone mobile

This project was an ethnographic inquiry into the use of the video function in mobile phone [START_REF] Bationo | Les usages amateurs de la video du téléphone mobile[END_REF] in daily life. Although the study concentrated on young adults, we think nevertheless that our results are interesting to investigate the potential of the mobile video in connection with the NAM++model.

What kind of technology?

The video phone mobile has two characteristics: It is a rudimentary tool because there is no basic functions like (zoom, …). It is a light handled device which is always with the owner, it is easy to use, and available anywhere, anytime. In our study, several children's participants used to borrow their parents' mobile phone for filming some scenes.

Methodology 19 participants were recruited for the ethnographic study. Some were young adults (15-25 ans) and some others were adults ( 25-40 ans). We collected video recorded by participants the last months before the interview. They transfer us their own video. We supplemented these videos with narrator's interviews supported by videotapes. All interviews were recorded and later transcribed. This is the agent contribution to the analysis of their activity.

Description of the narrative activity with model NAM++

Exploration. Videos taken by the participant group were short (2-3 minutes) and of many different situations: ceremonies (birthdays, weddings etc.), day-to-day life (meals, parties, children, etc.), holidays, concerts, sporting events, and less frequently landscapes and places. The videos were taken mostly spontaneously. Most often during a moment emotional, funny, or aesthetic significance for the person capturing the event. The participants produced blurred images, poorly framed. The visual quality of the video presented on the screen is inferior. What counts the most is not the image but what it allows them to tell.

Extract: " I film the baby. My 2 big daughters also film situations where there is their sister" (F, 35 y) Figure 3: Video of a daily event made by mother and daughters Inspiration -Production. Videos filmed on cameras usually require substantial editing, which correspond to the narrative activity [START_REF] Odin | Le film de famille : de merveilleux documents? Approche sémio-pragmatique[END_REF]. The mobile phone has broken this model of video production: both in filming and in narrative development. Most of the participant group did not edit. The videos were shared just after they were taken.

Sharing. Sharing is crucial in video mobile practice. Video are often taken in the idea of sharing. The sharing is nearly instantaneous with the taken of the videos. It is the idea developed by Tisseron [START_REF] Tisseron | Petite mythologie d'aujourd'hui[END_REF] of manipulated mirror. Most videos do not have narrative structure. They are showed immediately after the taken on the same device which permit to create them (the mobile phone).

Sometimes, video taken with mobile phone is a communication act. Videos are a stock of resources available and accessible anywhere, anytime to feed or provoke social interactions thanks to the possibility to visualize the videos on the mobile phone. For example to initiate a discussion about a hobby or a common activity like dance, music, sport… Extract: "I record musicans band and then I can show to my friends who play music with me " (H,15 y.) Some videos are used to illustrate his/her own interests, his/her friends or his/her family and their particularities. Videos are used (mobilised) as a self presentation. This absence of narrative structure grants them a polysemous character as far as they can feed and illustrate speeches at will recomposables.

What can we observe about children?

Children are actors during exploration, sometimes they are authors of mobile videos when they borrow their parent's mobile phone and they are often spectators during sharing.

Extract."when my daugthers film themselves, they show me then what they filmed by saying "mom looks "!" (F, 35 y).

As the adults, children do few editing. Sometimes they rename their videos files.

Extract. "Then they upload videos on computers they name files " TANA angry, TANA happy " DISCUSSION First, we can enumerate the characteristics of the experience conveyed by photos or videos in our two studies.

In his studies on the practices of the photography, Bourdieu [START_REF] Bourdieu | Un art Moyen, essai sur les usages sociaux de la photographie[END_REF] explained that the photo is a means to select pieces of past time, to fix extraordinary moment. It is a sort of voluntary memory. In our studies, phinoles reveal poetic aspects of environment. It is a singular and creative work about the usual environment. Images produced by pinhole permit users to revisit their familiar environment, to choose and to develop a singular point of view. The individual elaboration is important. In this case, time, quality and selection are important. Videos are most focalised on persons (my children, my friends…), and individual or collective activities (sport, music). The images are imbricated with the daily life. There is not an individual elaboration. There is a lot of diversity. Feelings and emotions are important.

Second, we can confront our results with the NAM model. Concerning the first study, pinholes do not permit to take a lot of photos. Participants have to choose a point of view. This necessary selection provides opportunity to be attentive, to revisit their environment. Elaboration is omnipresent during exploration, inspiration and production. Sharing is crucial for participants for expressing their own and singular point of view. Pinholes represent a good way to deploy the singularity of the person, to fix its, to work its and to confront it with other participants.

Video phone mobile enhance the taken of a lot of videos images during the exploration. It is a spontaneous attitude. During the exploration, it is a mean to capture feelings, and to cumulate a lot of sequences of daily life. Before the sharing, there is no inspiration and production, these videos are not really material to work with, to be edited. But sharing is important, and it is during this phase that inspiration and oral production occurs.

We think that these techniques present two different logics. 1) Develop a singular glance on shared spaces and experiences. Take self confidences. Pinholes could be used to develop imagination, to help children to revisit their habitual and common environment, to have a subjective and singular point of view and to work it, transform it and to be able to discuss, and confront it to the other persons. In short, it seems to us that pinhole an interesting tool for developing his/her imagining since exploration and during inspiration, production and sharing. It is a good mean to enliven children's imagination, as Vygotsky said emotion and feelings influence imagination.

2) Develop a common glance on singular spaces and experiences. Video mobiles are another status; they could be materials to collect the diversity of the children experience on a theme. These videos could be the starting point for a collective re-elaboration of experiences. In short, it seems to us that video mobile is an interesting tool for helping children to perform an active visual survey and to appropriate relevant points for understanding a theme, collecting experience materials relevant for this theme, as well as sharing and developing his/her imagination thanks to the diversity of the materials collected by other children.

Our challenge as designers, researchers, and educators, is to provide children with environments that enhance their desire to actively engage in the production of narratives that is to provide an enjoyable and enriching narrative experience. But the experience can be captured with different tools, and it is important to understand how these crystallizations of experiences can be worked in class individually, collectively, and their status in the narrative activity. It is a way to integrate children's experience in education.

Figure 1 .

 1 Figure 1. NAMC++ Model

Figure 2 :

 2 Figure 2: different steps of the process