中国科学院西双版纳热带植物园的名人名树园有一棵1986年由英国菲利普亲王手植的望天树，到现在已经有30年（http://www.xtbg.ac.cn/xwzx/zhxw/201503/t20150304_4317213.html），一直觉得不够高大、挺拔，而且分枝很低，和在野外森林中见到的望天树的高大形象不符。我之前猜想，是由于没有竞争，光环境太好，它不用拼命长高就可以获得在野外森林中要耸出才能获得的光资源。

今天早上看到biotropica上面的一篇文章“Tree Height Reduction After Selective Logging in a Tropical Forest” http://onlinelibrary.wiley.com/doi/10.1111/btp.12326/abstract?campaign=woletoc 

By harvesting scattered large trees, selective logging increases light availability and thereby stimulates growth and crown expansion at early-life stage among remnant trees. We assessed the effects of logging on total and merchantable bole (i.e., lowest branch at crown base) heights on 952 tropical canopy trees in French Guiana. We observed reductions in both total (mean, −2.3 m) and bole (mean, −2.0 m) heights more than a decade after selective logging. Depending on local logging intensity, height reductions resulted in 2–13  percent  decreases  in  aboveground  tree  biomass  and  3– 17  percent  decreases  in  bole  volume.....

明确证明我的猜想！