Felipe Ortega of King John Charles University in Madrid said the number of people editing the Web site shrank by 4,900 people during the same period of 2008, the BBC reported Wednesday.
"If the negative trend is maintained for too much time, say, one or two years, eventually the project could enter a problematic phase," Ortega said.
However, Michael Peel of Wikimedia, which runs the site, said the reduced number of editors is merely a sign of Wikipedia needing less input due to the presence of more experts.
"We're trying to engage a bit more at the moment with people who are very knowledgeable, people who are experts," Peel said.
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