Farmland and timber investing

Can anyone here recommend good resources/reads for timber and farmland?

"From 1992-2006, returns for timber were 12.2%. During the same time, large cap stocks returned 10.6%, small cap stocks returned 15.4%, international equities returned 8.2%, and corporate bonds returned 8.0%. When you consider volatility using the Sharpe Ratio, timber has the highest risk-adjusted returns, even beating small cap stocks (the Sharpe ratio for small cap stock was 0.63%, while reaching 0.84% for timber). Since 1987, the timber index has had only one down year in 2001 (-5.25%). During the same time frame, the S&P 500 has been down four times (as low as -22.10%)."