Introduction

The forest transition (FT, Mather 1992), the temporal change from net forest loss to net forest gain in a region, is characteristically driven by socio-economic changes. Two major pathways have been identified (Rudel et al. 2005), (1) economic development, which leads to agricultural dis-intensification in relatively marginal areas where spontaneous secondary forest succession subsequently takes place, and (2) scarcity of forest resources, which favors the expansion of tree plantations. Counterurbanization, neglected as a pathway of forest transition, may lead to forest recovery at local scale but becoming more widespread all over the world (McCarthy 2008; Ravetz et al. 2012; Taylor and Hurley 2016). Although the pathway we describe shares some features with both “classic” pathways, it also has particular features in terms of drivers, and social-ecological consequences.

Counterurbanization- often referred to as exurbanization, dispersed urbanization or amenity migration- is here approached as the increase in low-density settlements in rural areas, due to the temporal or permanent relocation of the urban population in the countryside (Mitchell 2004). Counterurbanization is indirectly driven by large-scale socio-economic and cultural changes, particularly the transition from manufacturing to service- and knowledge-based development (Ravetz et al. 2012; Taylor and Hurley 2016). In this context, the social perception of nature changes from valuing mainly resource extraction (e.g., timber, wood, agricultural products, water, soil) to a non-material value (e.g., esthetic, spiritual, inspirational, recreational); and rural environments emerge as important sources of natural amenities. The movement of urbanites to the countryside triggers economic and cultural changes that favor conservation and recreational activities at the time that extractive activities decrease (Taylor and Hurley 2016). Although counterurbanization is a multifaceted process in which residential and recreational uses can contribute to deforestation (e.g., built-up in pristine ecosystems, pastures for horses, Bock and Bock 2009), we focus on counterurbanization motivated by the natural amenities in former agricultural areas. In these landscapes, forest often expands on abandoned farmlands.

This perspective paper aims to bring together research on social sciences, land use/cover change and plant invasion to depict the FT counterurbanization pathway. We use scientific literature to achieve a general understanding of this pathway -and its outcomes- and we also used documented case studies (Fig. 1 and Table 1) to illustrate different mechanisms of counterurbanization around the world. To achieve this, the paper is organized into four main sections: (1) we first summarize the two “classic” forest transition pathways; (2) we present the counterurbanization forest transition pathway, comparing it with the traditional ones in terms of land cover patterns and new forest species composition. Based on the above, (3) we discuss socio-economic and environmental outcomes of each pathway. Finally, (4) we discuss emerging questions and research that would be necessary to improve our understanding of this process.

Fig. 1
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Geographic localization of the 17 case studies considered in this work (details of case studies are in Table 1, to display the location of case studies in an Earth browser, access to a KML file (Keyhole Markup Language) in “Electronic supplementary material”

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Table 1 Main characteristics of the case studies considered. NA not available in the paper, SR spontaneous reforestation, TP tree plantation
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Economic development and scarcity forest transition pathways

Forest transition has been documented at least since the late 18th century (Mather 1992), but it has accelerated and expanded in the last decades (Meyfroidt and Lambin 2011). Records of forest transition occurred in Europe and the United States in the 18–20th century, represented mainly by an increase in forest plantations. Currently, in these regions, most of the lands with forest regrowth potential have been colonized by woody species (Mather 1992; Meyfroidt and Lambin 2011). More recently (i.e., late 20th century) spontaneous FT and tree plantation expansion has been documented in rural and peri-urban areas of Latin America and Asia (Ashraf et al. 2017; Wilson et al. 2017; Nanni et al. 2019). Rudel et al. (2005) described two forest transition pathways that are currently widely recognized: (1) The “economic development” pathway results in spontaneous forest transition as a consequence of rural out-migration and agricultural dis-intensification, (2) The “forest scarcity” pathway mostly involves expansion of tree plantations as a response to increased demand of timber and other forest products.

The economic development pathway is associated with the national income increase, agricultural adjustment, and rural–urban migration (Meyfroidt and Lambin 2011; Redo et al. 2012). Urban economic growth increases the attractiveness of cities, as they represent opportunities for socio-economic development and access to employment, education and public services. On the other hand, agricultural mechanization leads to the concentration of croplands on flat and fertile lands, which reduces the demand for rural labor and the competitiveness of crops produced in less accessible lands with little technification, often managed by small producers (Rudel et al. 2019). The pursuit for human well-being, based on personal/familiar economic growth, is the fundamental driver of rural–urban migration (Rudel et al. 2019), and rural out-migration is associated with forest exploitation reduction (e.g., timber extraction and livestock grazing) and marginal cropland abandonment (Aide and Grau 2004). In areas where labor scarcity cannot be replaced by mechanization (mostly due to rough topography), agriculture tends to dis-intensify or be abandoned, sparing land for forest restoration and the spontaneous expansion of new forests (Meyfroidt and Lambin 2011).

The forest scarcity pathway is associated with a demand for forest goods and services. Forest cover reduction affects the supply of industrial materials (e.g., wood, pulp for paper, bioenergy) and services to the population (e.g., habitat for hunting, flood and erosion regulation) (Meyfroidt and Lambin 2011). In this context, forest plantations increase their profitability, which motivates landowners to replace crops and pastures with trees (Rudel et al. 2005). Currently, tree plantations represent around 7% of the world's forests, and they continue to expand (5.7 million ha/year between 1990 and 2020, FAO 2020). Reported cases of this pathway identify industrial plantations and reforestation promoted by governments (e.g., China) as the main responsible for the global increase in planted forests (McEwan et al. 2020). In some European countries, planted forests increased due to a decrease in timber importation after the First World War (Meyfroidt and Lambin 2011). There is also forest expansion by small scale plantations managed by local communities. Smallholders replace marginal crops in steep slopes and pastures with tree plantations to reduce labor and increase incomes in a relatively short time (Rudel et al. 2019).

The counterurbanization pathway

Counterurbanization is a distinctive feature of developed countries or comparatively developed locations in developing countries: it was registered for the first time in North America, Europe, and Australia in the 1970s when multiple authors identified rural population growth and an increase of low-density urbanizations (Mitchell 2004). In the 1990s, counterurbanization began to be documented also in the Global South (García-Ayllón 2016; Geyer 2018; Tu et al. 2018). Although this urbanization pattern is not new, its potential role in forest transition has not been addressed. We propose that social processes and land cover changes associated with counterurbanization drive forest expansion with particular characteristics (Fig. 2).

Fig. 2
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Conceptual model of the different forest transition pathways

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Mechanisms of counterurbanization

As most land use changes in the anthropocene, counterurbanization depends on globalized markets that influence decision-making and livelihoods, even at local scales (Verburg et al. 2015; Taylor and Hurley 2016; Cooke and Lane 2018). The raising of the service sector (e.g., commerce, tourism, health care, education; and an increased connectivity through transport and communication) in developed countries -or regions- promote rural economy restructuring, which in specific contexts implies a transition from traditional agriculture to nature-based land uses (Woods 2005; Abrams et al. 2012). Urban population revalue nature amenities, and the pursuit of a rural lifestyle and outdoor recreation prompts them to move to the countryside, forming low-density urban systems (Taylor and Hurley 2016; Cooke and Lane 2018; Shaw et al. 2020). The selected destinations combine proximity to developed large urbanizations (which facilitates access to infrastructure, health services and better education) with the environmental services provided by natural areas (Ravetz et al. 2012). Because newcomers have an idyllic perception of nature, they are frequently more motivated to protect or restore forests (Akgün et al. 2011). As counterurbanization progresses, rural economy is re-oriented toward tourism and real estate, strategies to preserve/create green spaces increase and agricultural abandonment accelerates (Woods 2005; Abrams et al. 2012; Shaw et al. 2020). Farming progressively becomes unprofitable in this context and counterurbanization also increases property prices reducing the possibilities of local people to maintain or buy new land (Woods 2005).

We propose counterurbanization-driven forest transition as a hybrid pathway between the forest scarcity and economic development pathways with specific emerging outcomes (Fig. 2). First, newcomers demand natural landscapes, which drives conservation strategies and thus resembles the scarcity pathway (counterurbanization-recreational demand, case studies 2, 3, 5, 6, 7, 8, 9, 10, 11, 138 14, 16 and 17 in Table 1). In addition, the change in rural lifestyle operates similarly to the economic development pathway, favoring the dis-intensification of agriculture, which may drive spontaneous reforestation (counterurbanization-agricultural dis-intensification, case studies 1, 2, 4, 5, 13, 15, 16 and 17 in Table 1). Although there is often a willingness to include only native species when designing these landscapes, non-native plants are frequently incorporated in the new forests (Abrams et al. 2012; Taylor and Hurley 2016), through accidental introductions with population mobility (e.g., tourism) and through the use of ornamental species in home gardens (Dehnen-Schmutz et al. 2007).

Counterurbanization also generates spatial patterns that differ from those of traditional FT pathways. Spontaneous forest transition via economic development has a scattered pattern of forest expansion in areas with reduced accessibility and affects large areas of the landscape; while the forest products scarcity pathway is located in productive, relatively accessible lands that allow the transport of forest products (Malkamäki et al. 2018; Nanni et al. 2019; Rudel et al. 2019). In contrast, FT mediated by counterurbanization is more likely to be spatially localized around accessible low-density residential areas, in places with particularly attractive climate, scenic or cultural amenities (e.g., coastal and mountainous areas, Table 1), and with good connection to developed cities (Ravetz et al. 2012; Taylor and Hurley 2016; Golding and Winkler 2020).

Recreational forest demand

Socio-economic changes in developed countries lead to new cultural values, increasing the positive perception of nature and demand for forests. However, unlike the forest scarcity pathway, such demand is not primarily for extractive purposes but for their esthetic, recreational and spiritual value (case studies 2, 3, 5, 6, 7, 8, 9, 10, 11, 14, 16 and 17 in Table 1; Hall and Müller 2004; Abrams et al. 2012; Cooke and Lane 2015). In the counterurbanization pathway, socio-cultural services valuation is incorporated into land use planning and management, and leads to an increase in protected forests and multipurpose plantations (case studies: 2, 3, 5, 6, 7, 8, 9, 10, 11, 14, 16 and 17 in Table 1; Hall and Müller 2004; Taylor and Hurley 2016).

Particularly in rural areas where agricultural use is decreasing, certain governments finance or provide legal incentives for the restoration of private lands, which has promoted the creation of protected areas with the aim of contributing to nature-tourism development (Taylor and Hurley 2016; Shaw et al. 2020). For example, the regulation of second-home development in the United States implies that a proportion of private lands must be kept undisturbed to promote conservation. Since these residential areas are commonly established near protected areas, they act as a buffer or expand their effective conservation area, thus contributing to nature conservation (Mockrin et al. 2017). Not only does the government promote reforestation, but new landowners are frequently willing to protect forests with their own funds because they assign a relational (emotional link with the landscape) or esthetic value to nature (case studies: 3, 5 and 14 in Table 1; Taylor and Hurley 2016; Shaw et al. 2020).

Active reforestation (tree plantations) for esthetic purposes has also become popular as a strategy to promote green tourism (case studies: 6, 7, 8, 9, 10, 11 and 14 in Table 1; Bock and Bock 2009). The design of these forests can vary among sites, according to the way in which nature is perceived by society: some people find scenic beauty in native species, while others prefer novel / unfamiliar landscapes dominated by non-native species (Kueffer and Kull 2017). For example, in some rural lands of Europe, newcomers planted native trees in order to conserve native biodiversity but also increase scenic views and promote forest cultural activities such as bird watching (case study 7 in Table 1). In contrast, some rural landscapes of Australia were reforested with non-native species which had esthetic value for landowners and were frequently used in gardens (case study 16 in Table 1).

Agricultural dis-intensification

Dis-intensification of agriculture in marginal areas (mostly due to steep slopes) in the context of socio-economic development is a well-known driver of forest transition. Counterurbanization often occurs in mountain and coastal settings which provide attractive landscapes and climatic conditions. In these contexts, urban developments compete for land with agriculture, and although rural out-migration might not occur in the counterurbanization pathway, economic restructuring toward the service sector outcompetes agriculture and livestock ranching (case studies 1, 2, 4, 5, 13, 15, 16 and 17 in Table 1; Woods 2005; Cooke and Lane 2015). Thus, local people frequently stay close to counterurbanizations and abandon farm activities to work in these emerging economic activities (Akgün et al. 2011). The availability of land with reduced intensity of agricultural use and seed sources allows the forest transition. Therefore, unlike the economic development pathway described by Rudel et al. (2005), in which rural dis-intensification usually occurs in remote areas, counterurbanization drives this process in arable lands located in populated, accessible areas.

In the counterurbanization pathway, non-native species are likely to be a key component of new forests (Kulmatiski 2006; Bock and Bock 2009). In the case studies we identified to exemplify this pathway, only five detailed the species composition; and of these, four included ornamental non-native species (case studies 1, 2, 7 and 12 in Table 1). Beyond these case studies, plant invasion studies have already demonstrated the role of urbanization and human population in the introduction and spread of non-native species (Taylor and Irwin 2004; Dehnen-Schmutz et al. 2007; Spear et al. 2013). For example, Taylor and Irwint (2004) demonstrated that real estate development has a strong and positive effect on the number of non-native plant species. Even in protected areas, the proximity to the human population was found to increase non-native species richness (Spear et al. 2013). Non-native tree species are mainly introduced for ornamental purposes, and they frequently establish in abandoned agricultural lands (Dehnen-Schmutz et al. 2007; Bock and Bock 2009). Once introduced, the probability of colonization of non-native species is potentially high in counterurbanized areas compared to cities because gardens would be closer to the abandoned lands (Marco et al. 2008).

Expected outcomes of the forest transition pathways

Socio-cultural impact

In the economic development pathway, decreasing agricultural profitability and urban development drive rural people out-migration (Rudel et al. 2019). The reduction of the family group limits activities that require manual labor, while migrants usually send remittances to their family for rural subsistence or investment in more profitable practices that may lead to declines in traditional farming (Hecht and Saatchi 2007). Although some stakeholders perceive an increase in the esthetic and recreational value of spontaneous reforestation as a consequence of out-migration, the contribution of the landscape to cultural identity is reduced, because migrating and remaining people drop traditional practices and lose the sense of place and cultural heritage (Martin-Fores et al. 2020; Table 2).

In the forest scarcity pathway, large-scale tree plantations have different impacts on local communities. In some cases, when families do not have property titles, land price increase around plantations forces them to out-migrate; land management by the government or private companies may restrict access to natural forests and thus limit community traditional practices (e.g., hunting or livestock ranching, Malkamäki et al. 2018). On the other hand, rural populations can benefit from infrastructure improvement, and employment opportunities increase due to the demand for labor on plantations, although these may be precarious and temporary jobs (Charnley 2006; Malkamäki et al. 2018; Table 2).

In the counterurbanization pathway local economic benefits arise when urbanites migrate to the countryside or carry out infrastructure development in rural areas, leading to emerging labor opportunities for local families (Woods 2005; Akgün et al. 2011; Taylor and Hurley 2016). However, counterurbanization also triggers socio-cultural conflicts between newcomers and local residents. For example, the increase in property prices and living costs reduces the possibility of purchasing land for the local young population and might force them to out-migrate (McCarthy 2008; Golding and Winkler 2020). In some cases, newcomers oppose traditional activities and try to impose their values and ideals on the rural community (Woods 2005; Golding and Winkler 2020; Shaw et al. 2020). The increase in land prices leads to the consolidation of property rights in areas in which they were previously loose. New residents start to delimit their properties with fences, restricting access to the local communities and their activities, such as livestock grazing or firewood collection (Hall and Müller 2004; Bock and Bock 2009). Although newcomers usually look forward to close interactions with natural environments, some unexpected negative interactions between wildlife and people arise when housing and natural ecosystems are interspersed: e.g., fear of attacks by large carnivores, traffic accidents caused by wildlife (e.g., deer), or domestic animal predation (Evans et al. 2014; Soulsbury and White 2015).

Urban expansion in rural areas may also lead to socio-cultural homogenization, loss of rural identity and a decrease in traditional practices (Hall and Müller 2004; Fang 2020). However, new landscapes can lead to increasing human–nature interactions and that some local traditions are reinvigorated to promote tourism (e.g., music, food and dance; Hall and Müller 2004; Fang 2020; Table 2).

Biodiversity and ecosystem services

Species composition and ecosystem services of new forests depend on multiple factors (e.g., propagules availability, soil properties, landscape connectivity, previous uses) that can lead to completely novel ecosystems (Hobbs et al. 2009; Morse et al. 2014). In this section, we discuss the environmental outcomes of the forests emerging under the three pathways (Table 2).

Table 2 Summary of most likely impacts of the different forest transition pathways. The arrows indicate the direction (red, decrease; green increase) of the effects on social-cultural aspects and biodiversity and ecosystem services. The sign “-” represents a null effect. The relative magnitude of the effect is represented by color intensity
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In the economic development pathway, new forests typically have greater biodiversity than previous agricultural landscapes, although secondary forests take a long time (decades to centuries) to reach primary forest structure and diversity (Wilson et al. 2017; Chazdon et al. 2020). Population reduction and passive reforestation also lead to an increase in wildlife because hunting pressure and fragmentation decrease and shelter availability increases (Navarro and Pereira 2015; Chazdon et al. 2020).

Spontaneous reforestation contributes to carbon sequestration, watershed conservation (Wilson et al. 2017; Chazdon et al. 2020), improves air quality and increases medicinal resources (through an increase in genetic diversity, Martin-Fores et al. 2020). Although reforestation reduces water yields due to an increased evapotranspiration, in the long term the pre-deforestation water levels are likely to be restored (Filoso et al. 2017). Also, as forest transition progresses, surface runoff decreases and soil erosion in secondary forests are reduced to similar levels to those of mature forests (Labrière et al. 2015).

In the forest scarcity pathway, plant biodiversity recovery is often comparatively lower since most tree plantations are dominated by a single species and in approximately 44% of the cases are non-native species (FAO 2020). Furthermore, this share is even higher in some regions of the southern hemisphere (e.g., in South America, 97% of the plantations are of introduced species, FAO 2020). However, tree plantations (especially with understory species) increase landscape connectivity, favoring wildlife movement and offering nesting, food and shelter for birds. Plantations can also act as buffers, reducing edge effects in native forests and indirectly contributing to preserving biodiversity (Brockerhoff et al. 2008; Paviolo et al. 2018; Pliscoff et al. 2020).

Tree plantations are generally dominated by fast-growing species, thus carbon sequestration and other provisioning services (e.g., timber, pulpwood and biomass for energy) are greater compared to spontaneous native reforestation (McEwan et al. 2020). Regulating ecosystem services provided by tree plantations depend on species composition and on the characteristics of the landscape. For example, Eucalyptus plantations have a high rate of water consumption; thus, they significantly reduce water yield while controlling soil erosion (Sun et al. 2018). Another important example with contrasting effects on ecosystem services of different regions are pine plantations. In high altitude paramo grasslands of Ecuador, these plantations were found to decrease soil carbon and nitrogen concentrations and reduce water storage capacity of the system (Farley 2008). On the other hand, in erosion-prone areas of Argentina, pine plantations increased water regulation services and soil protection (Wilson et al. 2017).

Counterurbanization pathway gives rise to novel systems through the introduction of non-native species, and it may lead to biotic homogenization (Bock and Bock 2009; Abrams et al. 2012; Morse et al. 2014; Groffman et al. 2017; Jimenez et al. 2021). For example, urban, suburban, and exurban areas of the United States have similar species composition, even though they are separated by large distances. Locally these residential areas increase their plant species richness because they include non-native plants with esthetic appeal, but native biodiversity is reduced (Groffman et al. 2017). The introduction of non-native plants also creates conditions that favor evolutionary diversification (e.g., via hybridization between native and non-native species) (Thomas 2015; Socolar et al. 2016; Vellend et al. 2017). It has also been shown that low-density counterurbanization can have positive effects on animal biodiversity (insects, birds and mammals), especially when there is a newcomer attitude toward conservation (Hansen et al. 2005; Bock and Bock 2009), although their species composition differs from natural environments with a high proportion of urban adapted species (Suarez-Rubio et al. 2011). Also, certain negative outcomes for wildlife, such as disease transmission by domestic animals, or reduction of top carnivore and ungulate populations due to fences and roads could also occur (Hansen et al. 2005; Kauffman et al. 2021).

Newcomers of counterurbanized areas often assign high value to cultural services including esthetic landscapes and historical heritage (Woods 2005; Duke et al. 2016; Davis et al. 2021).Counterurbanization FT provides ecosystem regulating services similar to those reported in traditional FT pathways, including carbon sequestration (particularly when fast-growing species are introduced), floods mitigation,watershed protection, timber supply and wildlife habitat (Huang et al. 2014; Duke et al. 2016; Davis et al. 2021). However, as new forests associated with counterurbanization expand in populated areas, the number of beneficiaries of local scale ecosystem services would be greater.

Toward further assessment of the counterurbanization forest transition pathway

Most of the counterurbanization studies have been conducted in the United States and Europe, where exurbanizations are widespread (Hansen et al. 2005; Groffman et al. 2017; Golding and Winkler 2020). Currently the counterurbanization process is spreading in different regions around the world at accelerated rates, which are even higher than urban cores (McCarthy 2008; Ravetz et al. 2012; Taylor and Hurley 2016; Shaw et al. 2020). As the economy of services and nature-based tourism increases, and as cultural shifts toward a high value of nature keep occurring (Winter et al. 2020), counterurbanization will be a more frequent land use change, with impacts on rural land covers and lifestyles (Ravetz et al. 2012; Golding and Winkler 2020). This will be facilitated by the proliferation of teleworking through good internet connection. The spread of Covid 19 during the last two years will probably speed up the counterurbanization process, as many previously reluctant individuals and organizations will be more open to teleworking scheme (Daniels 2021; Frumkin 2021).

To a great extent, the consequences of counterurbanization depend on the motivations and collective knowledge about the environment of the new inhabitants. Several studies have reported the loss of habitat and fragmentation associated with this process, while others have found positive impacts in forest cover, biodiversity, and ecosystem services in counterubanized areas (Taylor and Hurley 2016; Shaw et al. 2020). Therefore, the results of counterurbanization are highly heterogeneous and may result in totally opposite scenarios. A systematic typification and identification of variables leading toward different outputs is a research priority.

The cultural background and approach toward nature of exurbanites in different societies may shape the forest transition pathway. However, counterurbanization is usually led by a specific socio-economic group (upper-middle-class). This group has increased access to technical and economic resources, information and education, which increases the opportunities of replicating successful experiences and reducing undesired environmental effects. Despite commonalities of this socio-economic category, cultural differences are likely in different countries, regions and socio-ecological contexts, that likely result in different outputs and need to be further explored.

Analyzing the motivations of migrants, the diversity of the counterurbanization process (e.g., housing density, main economic activities, conservation strategies, land use management) and the impacts on forest transition features (e.g., species composition, ecosystem functions and extension of the new forests), will allow a deep understanding of this pathway. In addition to the environmental outcomes, each rural community has its own cultural identity, thus the social impacts of forest transition mediated by counterurbanization could vary greatly from one place to another. We hope the drivers and consequences that we described here can act as working hypotheses to refine the understanding of the expanding process, which would be useful to improve environmental quality and social well-being around the world.

Conclusions

Counterurbanization often promote local forest expansion due to land use changes leading to marginal agriculture dis-intensification and an increasing valuation of nature, thus resulting in a distinctive forest transition pathway. Counterurbanization is associated with socio-economic development, urban-like population increase in rural areas, diversification of productive activities, abandonment of marginal agriculture, and demand for attractive natural landscapes. This hybrid pathway of forest transition combines features of previously recognized pathways (“economic development” and “forest scarcity”), but also includes distinctive characteristics. Emerging forests tend to present an aggregated pattern around accessible, low-density residential areas with natural appeal, which are generally connected to larger prosperous cities. Often, they include a large share of non-native species that generate novel biotic communities and landscapes. Although there are positive contributions of non-native plants to ecosystem services and they might even increase local plant species richness, if they become invasive, they may lead to landscape homogenization. Regardless of the pathway, forest expansion often leads to increases in regulating services, although this varies widely according to the context and tree species identity. Although FT through counterurbanization is a spatially restricted process, it is taking place in various regions of the world. Given the current socioeconomic and cultural trends, and ecological globalization (McCarthy 2008), this process will likely accelerate in the future, creating scattered but widespread new ecosystems with novel environmental and cultural outcomes. The drivers and consequences here described can act as working hypotheses to lead further multidisciplinary empirical studies in order to refine the understanding of the expanding process.