I have the original paper of the article I posted. The research was done to investigate the mutualistic interactions involving two Myrmecophytic plants (neotropical myrmecophytes): Cordia Nodosa and Duroia Hirsuta and three ant species: Myrmelachista schumanni, Azteca spp., and Allomerus octoarticulatus demerarae. Apparently, not all the plants in the 'garden' are dwelled by the ants and there are 'competition' between ants and plants. For instance, the Duroia actually grow more fruits when Myrmelachista ants occuppied them. Another interesting fact that was not mentioned in the article, is the ants patrol their host plants to protect their hosts from herbivores. Some ants do better than the other in protecting their plants, others are just lazy. I enclose some data and facts from the paper below so you could have some references

-----------------------------------------------------
Quote:
Ant species did not inhabit equal shares of the host plant population20 % of Cordial and Duroia are unoccupied
3 - 4 % of plants other than Cordia and Duroia
Cordia -
Myrmelachista = 7%
Azteca = 19%
Allomerus = 51%
Duroia -
Myrmelachista = 65%
Azteca = 11%
Fruiting and floweringDuroia fruits more
95.8% of them occupied by Myrmelachista
4.2% of them occupied by Azteca
Behavior of antsThe ants patrol their host plants (Myrmelachiats and Azteca).
Allomerous workers do not actively patrol the trunks of their host plants, where beetles attack.
Myrmelachista clears vegetation from around Duroia and Cordia, not Azteca.
Azteca provides the most protection of leaf herbivore to Cordia and Duroia. A proposal – Azteca ants are common plant-ants because of their highly carnivorous diet makes them very effective guards.
Myrmelachista provides the most favorable light environment, and the data is biologically significant. The first documented ant species to use their poison, formic acid as herbicide.
Variation in host plantsAzteca occupied Cordia are larger, more growth, more frequent fruiting and flowering than Alleomerus occupied Cordia.
Myrmelachista occupied Duroia were larger and more fruiting and flowering but less growth than Azteca occupied Dutoia.