Picea Mill.species are important components of boreal and subalpine forests.They have a wide geographical range in the Northern Hemisphere,extending from the Eurasian continent to North America.In this study,publications on Picea species from 2002 to 2016 were identified via the Web of Science(WoS) and the China National Knowledge Infrastructure(CNKI) databases,and subjected to relationship network visualization using CiteSpace software.This study represents the first such analysis of Picea and provides a reference for bibliometrics in forest tree species research.The results show that the total number of publications on Picea archived in WoS was20,958 and that the number of papers published annually has increased over time,peaking at 1725 in 2013.The studies were mainly conducted in North America,Europe and Asia;among them,Canada published the most papers and showed the strongest betweenness centrality(0.11).Among research institutions,the Swedish University of Agricultural Sciences in Uppsala had the highest publication record.The research contributions of the Chinese Academy of Sciences,the Chinese Academy of Forestry,and Beijing Forestry University have improved rapidly in recent years,greatly enhancing the international impact of Chinese research in this field.The research contents were grouped into five categories:forest ecosystems,pest resistance,extraction and functional analyses of active ingredients from various plant organs,nursery and afforestation techniques,and timber quality research.In China,the number of papers from the CNKI database was4532,increasing at an even pace.The research topics on Picea included forest ecosystems,seedling and afforestation techniques,basic studies on individual species and populations,and pests and diseases.Within and outside China,hotspots in Picea research included the relationships between Picea and environmental factors,and the genomic sequences of Picea.
