Okay this article is primarily about bird life ...what I found interesting was the references to shade coffee and cacao et al ...don't know if we can source in Thailand but under our rubber ,fruit trees etc could be worth investigating ...will do on google and advise....555

http://www.sciencedaily.com/releases/2012/08/120807101357.htm

Up North west of Chiang Mai they grow coffee under the rain forest canopy, it is supported heavily by some American church group. But, correct me if I am wrong, rubber is suited to high rainfall "coastal" areas such as southern Thailand, and coffee is suited to the cold area typically found in the north?

I have seen with younger rubber trees, people grow lines of vegies and crops like lemon grass in rows between the young rubber trees.