**2. Methods**

Systematic mapping is a method to describe the literature across a broad subject of interest. It does not attempt to answer questions that require critical analysis; instead, it describes available evidence; this is useful to identify general patterns and knowledge gaps about the research topic [49]. Systematic mapping formulates a narrative description of the state of the evidence base [50]; this descriptive approach is similar to other published review studies [50–52]. We conducted a systematic mapping to catalog all the published scientific articles about Historical Ecology in Brazil in Portuguese, English, and Spanish until May 2021. We excluded other publications such as books, book chapters, theses, congress memories, and other grey literature, as the amount of information, accessibility, and effort overpassed our ability to manage all the information. We are aware that many research results are published in the form of books in the Humanities. We found some titles specifically about Historical Ecology in Brazil [53–56]. Other books contain chapters dedicated to Historical Ecology research in Brazil [57–60]. The majority of the editors of these books have also authored scientific articles selected in this systematic mapping. The books and book chapters mentioned are mostly about studies in the Amazon. In a quick search for examples of postgraduate theses, we found a greater diversity of biomes studied [61–65]. We pursued the following steps:


somewhere else; (b) referred to Historical Ecology as a field related to evolutionary ecology [2]. After these four stages of filters, we had 118 articles to review in-depth.

While reading the articles, we discovered that, in many cases, Historical Ecology was explicitly the main research topic. In contrast, in other times, it was applied as an auxiliary notion to support or to dialogue with an investigation topic in a correlated field. Some examples about the use of Historical Ecology as an auxiliary notion are a publication in environmental public policy [67] and another in political ecology [68] that only mention briefly Historical Ecology in its research. This study includes articles having both, Historical Ecology as main or as an auxiliary research topic.

### *2.1. Variable Design and Analyses*

We designed the variables to overview by whom, where, when, what, and how Historical Ecology research was conducted in Brazil. For the question "by whom"—we included variables of authors' affiliations (as stated in the article at the moment of publication), gender, journal of publication, and language. We determined gender through the author's name and an author information search on the internet and applied a classification of women and men. Although we are aware of the diversity of gender types, we opted for a binary gender classification for practical reasons as questioning all authors about their gender affiliation was out of the scope of this study. We classified the departments and research centers of affiliation of the authors in general fields of knowledge. This gives an idea of the fields that embrace Historical Ecology in their research. It is common to find a department named with more than one field of knowledge, for example, "Department of Geography and Environment," in these cases, we counted it in both areas, geography and environment. Another frequent union is of archaeology and anthropology, or ethnology and history. Concerning the publication journals, we verified their inclusion in the CAPES/MEC Portal of Journals from the Brazilian Ministry of Education (http://www.periodicos.capes.gov.br/, accessed on 1 June 2021). This virtual library subsidizes and provides free access to scientific publications for all education and research institutions in Brazil.

For the question "when"—we had two different approaches. On the one hand, we registered when the articles were published. On the other hand, we were interested in the historical period studied in the papers; we categorized the temporal scales: geological era, before the 16th century, 16th, 17th, 18th, 19th, 20th, and 21st centuries. We registered the references to different times of history in the articles. Each article often referred to several epochs, and so we registered.

For the question "where"—we had two different approaches. On the one hand, we considered the studied biome and, on the other hand, the spatial scale of the research. In Brazil, the biomes are well-characterized as Amazon, Atlantic Forest, Cerrado, Pampa, Caatinga, and Pantanal [69]. To have a spatial idea of where research is concentrated, we mapped the number of authors in Brazil per city according to affiliation and the number of works per biome. We also compared the biome of affiliation's city with the studied biome to know if the authors research where they are based. Concerning the spatial scales, we categorized them as local (i.e., specific sites or landscapes), regional (e.g., a large river basin or portion of a biome, like southeastern Atlantic Forest), biome, national, international (i.e., global, continental, intercontinental studies).

For the question "what"—we included the keywords and the specific species studied. We gathered all the keywords, translated and standardized for singular (i.e., we count the word 'forests' as 'forest'). We placed them in a word cloud (https://www.wordclouds.com, accessed on 1 June 2021), where the font size differentiates the number of mentions; the bigger the letter, the more it was mentioned. For the plant species, we revised the updated scientific names in the Tropicos database (http://tropicos.org, accessed on 1 June 2021).

For the question "how"—we verified whether Historical Ecology was the main research topic or if it was used as an auxiliary topic, as explained in the previous section. We also focused on the methodologies employed in the papers. The use of a mix of methods is usual in Historical Ecology studies. However, we considered it relevant to differentiate

between theoretical and in situ fieldwork-based approaches. We classified an article as 'practical' when the researchers did fieldwork, using diverse methodologies in situ; when they explicitly expressed that they went to the location of study to collect data, such as archaeological excavations, botanical collections, water and soil sampling, interviews to local people, among others. In contrast, we classified as 'theoretical' research papers to those that did not carry in situ fieldwork, such as consulting historical archives, literature reviews, or other ex situ methods.

In order to assess these variables, we had two members of our team reading each article and extracting the information for each variable. After that, if there were any conflicting interpretations about the assessment, it was discussed in our weekly meeting.

In the results section, we cited each of the 118 articles found in this systematic mapping at least once so that the readers have access to a comprehensive review of the Historical Ecology in Brazil through the references. The multiple citations to the studied articles along the text are helpful to present various perspectives and topics dialoguing with Historical Ecology.
