Planting trees at Yahoo…

They say planting trees shows faith in the future. In corporate suites, the equivalent guesture would be buying stock in your own company.

And behold, Sue Decker, Yahoo’s president is buying stock. And lots of it. In a Form 4 filed Thursday, Decker paid about $1.1 million to buy 47,000 shares on the open market. It’s her first open market purchase since 2001, when as CFO, she bought 10,000 shares for a total of $58,241.

Over her career as an insider at Yahoo, she’s sold about 2.6 million shares to collect $80.7 million, for a net gain of $63.4 million.

But being a bit of a wet blanket, former chief executive and now director Terry Semel made about $1.5 million selling 100,000 shares on the same day.

Yahoo’s stock closed Friday at $23.94 per share, well below its peak this year of $33.61.

Should Google be nervous?

Well