When analyzing the geographical distribution of the studies, we observe that the main countries addressing urbanization are predominantly in less industrialized regions, including Brazil, Argentina, Mexico, and China. Except for a few studies from European countries, most of the research originates from countries with lower human development indices [51]. Studies conducted in Europe predominantly focus on understanding how urbanization affects the consumption of forest fuels [52,53,54]. In contrast, research from less industrialized regions places greater emphasis on understanding how urbanization affects knowledge about plants used for food and medicinal purposes [9, 10, 25, 33, 37, 55,56,57,58]. This discrepancy points to a clear differentiation in the focus of research between the regions, possibly influenced by the different socioeconomic and environmental realities faced by each one, and by the different urbanization processes that each region presents [1].

A study on the growth of ethnobiological research in Latin America revealed findings that align with our own, identifying Brazil, Mexico, Peru, and Argentina as the foremost contributors in terms of publications in the field [59]. This surge in research output is credited to the presence of academic institutions that actively foster ethnobiology through dedicated courses, programs, Latin American ethnobiological societies, and scientific conferences, all of which enhance scholarly discourse in the area. Additionally, these countries are prominently featured in another systematic review, which highlights the significance of the biocultural approach prevalent in Latin American ethnobiological studies. This approach is crucial for bridging local knowledge with scientific inquiry, further strengthening the integration of diverse knowledge systems [60].

Our results reveal a widespread sampling issue in the analyzed papers, which hampers our ability to identify clear global trends regarding the effects of urbanization on local ecological knowledge (LEK). A study that examined bias risks in ethnobiological research on medicinal plants in Brazil reported similar findings, noting a high proportion of studies with significant sampling problems and classified as high bias risk [28]. However, it is important to note that high or moderate bias risk classifications do not always indicate genuine sampling problems. Often, these issues arise from a lack of detailed information on the sampling universe or sample size [28, 61]. Our results support this observation, as many papers lacked detailed information about the sampling universe or sample size, resulting in high bias risk classifications. Providing a more thorough description of the experimental design in these studies could address these issues, reducing doubts and subjectivity [28, 62]. Clarifying these aspects would offer a more robust foundation for evaluating the impact of urbanization on LEK, leading to a more reliable and comprehensive understanding of this complex relationship.

We also found another trend in ethnobiological studies, the concentration mainly on assessing the knowledge about medicinal plants in the face of urbanization [38, 39, 41, 63], with little interest in understanding how urbanization affects the use and consumption of other biodiverse resources. Although this is a common approach in ethnobiology in general, it is also worrying, since an individual might remember and even mention beneficial natural resources when questioned or in response to some sensory stimulus [64]. However, the effective use and consumption of these resources can decline in the face of the sedentary lifestyle that urbanization often foments, resulting in, for example, the increased consumption of processed foods [65, 66], the use of modern fuel sources [2] and the preference for using industrialized medication instead of medicinal plants [13].

Our findings reveal a significant gap in ethnobiological studies focusing on urbanization regarding the precise definition of the term. Researchers often treat urbanization as a well-established concept without requiring a formal definition. However, it is important to acknowledge that different interpretations of urbanization emerge, reflecting the various facets of the concept [9, 26, 31, 67, 68].

The papers that provided explicit definitions of urbanization agree on its characterization as a complex economic process marked by rapid social and environmental changes. They describe urbanization as a consequence of continuous population growth, which alters both human lifestyles and land use patterns [9, 26, 31]. In the Hussain and Imitiyaz study [6], the authors conceptualize urbanization as a complex social phenomenon encompassing multiple dimensions that can be analyzed from various perspectives. This inherent complexity contributes to the interdisciplinary nature of urbanization studies, leading to a range of definitions and interpretations of the term [6, 9, 31].

Although most of the papers analyzed did not present a concept for urbanization, they presented two strands to characterize their areas of interest. The first strand addresses the absence of urbanization indicators, where the authors decided to focus merely on the urban–rural dichotomous classification. The use of this categorization, which separates urban and rural areas, is probably associated with previously established spatial limitations, reflecting the preference for an easy-to-understand classification, which considers the typical characteristics expected in each of these distinct regions [69,70,71]. Urban areas tend to have a high population density, with a notable concentration of buildings, advanced infrastructure and a diversity of industrial, commercial and service activities [6, 72]. In contrast, rural areas are distinguished by their lower population density, characterized by the presence of open spaces and the predominance of agriculture, livestock and extractive activities [6, 72]. Countries such as Brazil, the UK and South Africa use this dichotomy for the political and administrative delimitation of their territories [6, 72].

Nevertheless, it is crucial to emphasize that the application of the dichotomy between urban and rural presents significant limitations [73], and its use may have scientific implications in studies exploring urbanization’s impact on local ecological knowledge. This is due to the fact that this dichotomy establishes a clear opposition between the two poles, strictly outlined and mutually exclusive. However, it is possible to observe situations in urban areas that exhibit characteristics similar to rural ones, just as rural areas may present attributes considered urban, such as access to mobile and internet services, even in regions officially designated as rural [10, 72]. Despite the dichotomy that is very common in ethnobiological studies, the complexity that urbanization represents for the present requires more comprehensive and updated approaches if the intention is to represent it in studies.

The second strand observed to characterize the study areas of the analyzed papers addresses the use of urbanization indicators. Even without an explicit concept of what the authors considered urbanization (except for the studies of Arjona-García et al. [9] and Collier et al. [31]), it is clear that there is an intrinsic understanding that urbanization can be measured by some factors [19, 23, 47,48,49], which will be discussed in the next topic.

Urban ethnobiology focuses on understanding the dynamics of knowledge in urban contexts, encompassing both traditional elements—such as family practices—and new practices and knowledge systems. These emerge from the interactions between local populations and immigrant groups, creating a multicultural landscape unique to urban settings [74]. Urban ethnobiology has significantly advanced the theoretical and methodological understanding of local ecological knowledge in urban and peri-urban environments [74,75,76,77]. However, this field often overlooks the full range of the urban–rural continuum, leaving rural LEK dynamics underexamined [78].

Recent research in urban ethnobiology introduced the term rurbanity to describe the transitional spaces between urban and rural areas [79]. This interdisciplinary concept suggests that while urban and rural areas remain distinct, they coexist and interact within the same geographic space [80]. Rather than viewing urbanization as a one-way process in which rural areas inevitably become urbanized, rurbanity highlights a continual interaction between the two, where rural characteristics can influence urban areas, resulting in a hybridized space that reflects both influences.

Another relevant concept, widely used in public health studies, is urbanicity [73, 81, 82]. Urbanicity refers to the presence of typical urban attributes, which can also appear in non-urban areas at particular times [73, 83]. This concept recognizes the fluid transitions between rural and urban environments, moving beyond strict geographical boundaries and acknowledging various degrees of urbanization.

Both rurbanity and urbanicity offer valuable frameworks for ethnobiological research. Urbanicity provides a more comprehensive approach, capturing the full spectrum of the urban–rural continuum, while rurbanity focuses more specifically on peripheral, transitional areas often defined by geography or socioeconomic factors [79]. Urbanicity’s multidimensional approach, which includes social, physical, and infrastructural aspects like access to commercial and health services, further enhances its utility in examining how urbanization impacts local ecological knowledge [84]. This broader scope makes urbanicity particularly effective for understanding the interplay between urban and rural influences on knowledge systems.

We found a variety of indicators that characterize urbanization in the analyzed studies, and from this it was possible to perform multivariate analyses, which mainly showed us that the understanding of urbanization of the papers is evidently heterogeneous. That is, despite the formation of groupings in the PCA, most indicators have a low relationship between them. This low relationship suggests that a more integrated, possibly multidimensional approach may be more appropriate to capture the true complexity of urbanization.

The most used urbanization indicators deal mainly with demographic, infrastructural and economic aspects. Within the demographic aspects were used mainly population size [19,20,21, 23, 44,45,46,47,48] and demographic density [19,20,21, 23, 44,45,46,47,48]. The use of these indicators is fully justified, since urban or highly urbanized areas are characterized by a significant concentration of people in restricted spaces [6]. However, even areas with low demographic density and small population size may have characteristics of urban areas [72].

The structural aspects most associated with urbanization were distance, time and access to the urban center, access to healthcare services, education, electricity, roads and access to the public transport system. Among these, the distance to the urban center is the most used indicator [10, 19, 23, 40, 44, 47]. However, this indicator has limitations since a greater distance may indicate less access to urban centers. However, if a distant rural community has access to an efficient transportation system, the frequency of commutes to urban centers may be higher than to a community closer to the urban area. Thus, the relevance of this indicator could be expanded if it adopted a multidimensional approach, encompassing elements such as distance, transport system, existence of paved roads, among others [19, 47].

It is necessary that the indicator of economic activities be multidimensional. Historically, rural areas are associated with primary economic activities, while urban areas relate to secondary and tertiary activities. On the other hand, a new set of activities beyond the primary has been observed in rural areas [1, 20]. This phenomenon includes the appreciation of countryside regions, motivated by factors such as abundant biodiversity, picturesque landscape heritage and a better quality of life [72].

Urbanization can be understood as a complex phenomenon, which encompasses a wide range of transformations in socioeconomic aspects, in access to essential goods and services, and in the relationships of human populations with the natural environment [6, 9, 31]. Given this complexity, the most appropriate approach to examine urbanization in the context of ethnobiology would be one that encompasses the social, environmental and infrastructural aspects of the studied regions. An effective approach is the adoption of urbanicity. As discussed earlier, urbanicity offers a multidimensional framework that integrates social, physical, cultural, and environmental dimensions [84]. This concept resonates with the way ethnobiologists have come to understand urbanization, as the urbanization indicators examined here align closely with the principles of urbanicity. Furthermore, the most frequently employed urbanization indicators in ethnobiological research already fit within the various scales of urbanicity developed by public health scholars[