Charity Navigator, which rates the financial standings of thousands of nonprofit organizations, claims that only 41 percent of the money raised by a celebrity-studded 2006 Carnegie Hall concert actually funded tree-saving programs, Monday's New York Post reports.
The benefit featuring Lenny Kravitz, Sheryl Crow and Will Ferrell brought in more that $2.1 million.
Styler points out that "The Rainforest Foundation is celebrating its 20th year. We wouldn't still be in business or have given out millions of dollars over the years if we'd spent everything we made immediately after it came in."
In 2006, the charity reported $10 million in net assets – including nearly $5 million in cash – to the IRS.
"What are they doing with the money?" Bennett Weiner, the director of the Better Business Bureau's Wise Giving Alliance, mused to the Post after examining the fund's tax forms.
"They have more than five times what they would normally spend in a year in reserves."
The rocker's annual Carnegie Hall concert is set to take place later this month with performances by Billy Joel, James Taylor and Brian Wilson.