Tree species rankings based on publication rate (North America)

A ranking of North American tree species based on keyword searches of genus and species using Web of Science, AGRICOLA, and CAB Abstracts. A bibliographic analysis using three bibliographic databases was conducted to understand the importance of North American tree species in literature published since 1900 and since the development of the last Silvics of North America in the 1980s. The Silvics of North America is the most comprehensive guide to North American tree-like species containing about 200 of the 696 tree-like species found in the literature. Depending on the bibliographic database, over 100,000 to over 600,000 publications on the 696 plant species can be obtained. At least half of the publication records are from 1985 forward. The ranking in this database is based on the average rank of six bibliographic searches (three bibliographic databases and two time frames: 1900-2020 and 1985-2020).

Methods
Keyword searches of genus and species using Web of Science, AGRICOLA, and CAB Abstracts were conducted in January and February 2020. Search queries were conducted in English, using contemporary taxonomy (genus and species identifiers and their surrogates), as suggested through Silvics of North America (Burns and Honkala 1990) and the U.S. Department of Agriculture PLANTS database. The initial set of tree species were derived from SNA and supplemented with species that were identified as having a tree-like growth quality from the U.S. Department of Agriculture PLANTS database. Duplications of genus and species identifiers were resolved by carefully examining each genus/species combination. Some tree species were combined as a result into one instance of a species, when they used the same genus/species combination. Other tree species had to be carefully evaluated to avoid double-counting search results. For example, Pinus monophylla (western white pine) is also known as a variant of another species, Pinus edulis var. fallax. Therefore, the query for western white pine contained a criterion using the Boolean operator OR (“Pinus monophylla” or “Pinus edulis var. fallax”). However, when Pinus edulis (twoneedle pine) was assessed, it required a criterion using the Boolean operator NOT (“Pinus edulis” not “Pinus edulis var. fallax”). Common names were considered for inclusion in the queries using the Boolean operator OR (e.g., OR “common name”), however several tree species shared common names and the query results could not be disentangled. The term “North America” was not used as a keyword (as topic or in “all fields” in these queries as it acted to severely limit the results. In fact, in limited tests using this term, no results were returned when queries included AND “North America”.

本数据集为北美树木物种的排名榜单，其基于Web of Science、AGRICOLA及CAB Abstracts三大文献数据库中针对属和种的关键词检索结果生成。本研究依托上述三大文献数据库开展文献计量分析，旨在厘清1900年以来，以及1980年代《北美树木学》（Silvics of North America）首次出版以来，北美树木物种在相关学术文献中的受关注程度。《北美树木学》是目前针对北美木本植物最全面的权威指南，文献中记载的696种木本植物中，该指南涵盖了约200种。针对这696种植物，不同文献数据库可检索到的相关文献量从10万余篇至60万余篇不等，其中至少半数文献记录的发表时间不早于1985年。本数据集的排名基于6组文献计量检索的平均排名结果生成，涵盖3大文献数据库与2个时间区间：1900-2020年及1985-2020年。

研究方法
本研究于2020年1-2月依托Web of Science、AGRICOLA与CAB Abstracts三大数据库开展属、种层面的关键词检索。检索式以英语编写，采用《北美树木学》（Burns与Honkala，1990）及美国农业部植物数据库（U.S. Department of Agriculture PLANTS Database）推荐的现行分类学标准，含属、种标识及其替代术语。初始树种数据集源自《北美树木学》，并通过美国农业部植物数据库补充了被鉴定为具有木本生长性状的物种。研究人员通过逐一核查每个属-种组合，对重复的属、种标识进行了去重处理：若多个条目使用完全相同的属-种组合，则将其合并为单一物种条目；另有部分物种需经严格甄别，以避免检索结果被重复计数。例如，单叶松（Pinus monophylla，俗称西部白松）曾被归类为二针松（Pinus edulis var. fallax）的变种，因此针对西部白松的检索式需采用布尔逻辑或（OR）运算符，即检索词为"Pinus monophylla"或"Pinus edulis var. fallax"。而在检索二针松（Pinus edulis）时，则需使用布尔逻辑非（NOT）运算符，即检索词为"Pinus edulis"且排除"Pinus edulis var. fallax"。研究曾考虑将通用名纳入检索式，采用布尔逻辑或（OR）运算符（如"OR 通用名"），但由于多个树种共享同一通用名，导致检索结果无法区分。本次检索未将"北美"作为关键词（未在主题字段或全文字段中使用），因为该术语会大幅限制检索结果。事实上，在前期测试中，当检索式加入"AND "North America""时，未返回任何检索结果。