Key points are not available for this paper at this time.
Robert E. Ricklefs, Roger Earl Latham, Hong Qian, Global Patterns of Tree Species Richness in Moist Forests: Distinguishing Ecological Influences and Historical Contingency, Oikos, Vol. 86, No. 2 (Aug., 1999), pp. 369-373
Ricklefs et al. (Sun,) studied this question.