As Frances says this is a complex subject. The best way I have found of looking at the final arrangement of Treens and Quarterlands is that in the historic period that we have record of, the quarterland was the practical holding which had a living significance, the Treen was just a legal grouping used for administrative purposes. Once you go back into the period when there was a proper social cross section on the Island, covering the whole range from King, nobles, chiefs, freeman, bondsman, slaves, then the Treens had much more practical importance, and my reseach suggests that the treen expressed the exact nature of each individual or family's precise social position.
The creation of the parish boundaries and the donation of estates to the Church, was one of the major disruptions which took place before this broke up, followed by the removal of the upper layers of society. At some stage the countryside was converted - levelled - into a two tier society of Lord's tenants and sub-tenants or cotterells, and at that stage, the four quarterland thing seems to emerge, and the treen die away. This was obviously well before the Manorial Roll period of 1490's on. I am analysing the morphology oif the farms, and the meaning of the family names, and I have hopes that eventually I will be able to explain all this a lot more clearly.

At the moment I am puzzled about why a disproportionate number of "Treen Farms" with Gaelic names were occupied by the MacHelly family (Kelly) at the time of the oldest rent rolls. A Treen farm is a quarterland that has the same name as the treen itself. Obviously Kelly is the most popular Manx surname, but it seems a bit disproportionate that there are so many treens where the only quarterland with Kelly in is the Treen farm.

See what you think. THis cannot be applied to

1. Treens where the Treen Name is lost from the Treen Farm.
2. Treens with Norse names

NGC

Ballanicholas
Ballayeman
Baldalbrew
Middle
Camlork
Orestall (with MacCorleott)
Ballyhestin