Wikipedia’s exponential growth over this decade is due to the efforts of the millions of volunteers who write, edit, and check its entries. But could that volunteer effort now be in danger? Volunteers have increasingly been quitting Wikipedia en masse for a variety of potential reasons, according to Monday’s Wall Street Journal. More than 49,000 editors left Wikipedia’s English-language edition during the first three months of 2009, compared with only 4,900 for the same quarter a year earlier, according to the Journal, quoting Spanish researcher Felipe Ortega, who analyzes Wikipedia’s online data. Though the service still boasts about 3 million active contributors, volunteers are leaving more rapidly than new ones are joining, the Journal said. Several reasons for the decline in volunteers have been offered by Wikipedia contributors, noted the WSJ. Many subjects have already been fully written about. The site has also enacted an array of rules to limit conflict among people who contribute to the same entries, especially on controversial subjects. But the rules often trip up new contributors who find their content removed without understanding why.