The Forest Primeval?

according to this article, there is no fixed mix of plants in a forest community
so creating a useful guild or forest garden different from what's currently there isn't "going against nature"  experiment and plant away

what remains the same is the levels: canopy, mid-level, shrubs, climbers, groundcover, etc

http://www.newscientist.com/article/mg20827821.000-the-chaos-theory-of-evolution.html
The chaos theory of evolution

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"In the 1970s and 1980s, palaeoecologist Margaret Davis at the University of Minnesota in Minneapolis created a map using this data which showed how North American tree taxa reached their respective present positions after the glaciers retreated at the end of the last ice age.

She found that the distribution shifts were individualistic, with huge variations between species in the rate, time and direction of spread. For example, larch spread from south-west to north-east, white pine from south-east to north-west. Rates vary from 100 metres a year to over 1000 metres (Annals of the Missouri Botanical Garden, vol 70, p 550). In other words, trees show no predictable response to climate change, and respond individually rather than as communities of species.

The fossil record also tells us that the make-up of modern forest communities differs from those of 20,000 years ago. Today we recognise various types of forest, such as boreal, deciduous and aspen parkland, each with a distinctive mix of tree species. Yet the fossil record tells us that these are just temporary groupings. Multi-species communities do not have long histories and do not shift their distributions in a coordinated way in response to climate changes, as Darwin supposed. We therefore cannot assume that the members of modern forest communities evolved together or are somehow dependent on each other.

The same appears to be true over longer timescales. Pollen data show that during earlier interglacial periods, when the climate was most similar to now, forest compositions were very different from today."

And of course, the mix is not only not fixed, it's not even "natural" in most cases, because it's been tampered with by humans for millenia.
Charles C. Mann's '1491' is a very good source of information for this.

'Stop farming in places like tropical rainforests, which have high ecological value and low food output' -
only a particular form of ignorance can produce such a recommendation:

http://www.grist.org/population/2011-10-13-we-can-feed-10-billion-of-us-study-finds-but-it-wont-be-easy

I know I have read a lot about this subject in several books, just can't remember which ones..

My North American Wildlife book has a section of successonal forests that is quite interesting

Seems to me that species fluctuate a great deal, but the general pattern of the ecosystem changes slowly. Which is basically what permaculture operates upon.