[permaculture-oceania] Acacia - symbiotic or allelotrophic?

[jedd]

 A segue from my current heterogenous hedge deliberations .. 

 On a bamboo list a while back I saw a reference to the benefits of
 growing an acacia near a clump of bamboo.  Seemingly 'boo is one
 of the few things that won't be out-grown by these things, and more
 to the point, seemed to get a distinct boost from having one as a
 neighbour.  I think this was mostly empirical rather than solidly
 research evidence.  It makes sense, given the extra shading to the
 ground, and the high nitrogen requirements of bamboo.

 However, I've also read that acacias can suppress growth of nearby
 plants, which may just be a companion plant mismatch with whatever
 happened to be growing near these particular examples, or perhaps a
 resource (water, nutrient, light, etc) competition problem .. but the
 implication was that acacias, at least some of them, are genuinely
 allelotrophic (sp?).

 Personal observations are most welcome.

 [ I have a couple of acacias of unknown variety very close to a
 couple of B. multiplex - one variety of which is my sole specimen,
 so no control to compare with, but I do have a few Alphonse Karrs
 both near and far from acacias.  Only a few years old - 'boo and
 acacia both - but casual observations suggest neither benefit nor
 detriment to the 'boo.  Payoff (or otherwise) may take a few more
 years however. ]

 Jedd.