Locust trees give off toxins that make the leaves hard to breakdown by insects, and I think one of the toxin classes will effect other plants also.

Do you have any links to information on locust toxins? I work with several species, and a couple of genus'of of locust and would be interested.

http://www.vet.purdue.edu/depts/addl/toxic/plant48.htm

As an example. I noticed how earthworms did not do well under the locust trees and the leaves did not break down. Spend 1/2 a day, found enough other data to say to myself 'stop composting these leaves' then moved on.