The pinnacle of the ranger skillset, the most potent of the profession's powers, are to be found under the banner of Sylvanlore. The Sylvan specialisation is attained through reaching a highpoint of affinity with the forests of Avalon and maintaining it over many Avalon years. There is an element of competition in the forest affinities, since your woodland sympathies are pitted against others in the ranger and druid profession; though often a consensus is reached with certain forests declared the domain of the ranger, others under the wing of the animists. The land's current political climate will doubtless affect whether an individual's pursuit of Sylvanlore is a case of competition or consensus.
Here is the precise process for advancing towards gaining Sylvanlore, for those in the ranger profession: Every Avalon month the forests of the land will register their affinities and, depending on the size of the forest, any active member of the ranger profession in the top five 'highest affinity' possessing the Falconry skill will gain a little "forest empathy". See HELP FALCONRY for info about that first-stage ranger specialisation. You will be informed each new day you enter Avalon how your "forest empathy" is progressing, as a percentage, towards the eventual attainment of Sylvanlore. Eventually, providing you have gained sufficient "forest empathy" you will crossover 100% of what's required and - in a way everyone in the land will see - Sylvanlore will be acquired.
You can increase the speed of your attainment of the aggregate forest affinity required to gain Sylvanlore via the TEND FOREST command. This is begun at certain specific locations (varies from ancient forest to forest) in all the larger woodlands and takes you through a circuit that will use lessons to advance forest affinity. You may use darsurion here if you are tending using your lessons - for acquisition of Sylvanlore (as opposed to tending for affinity-gain). The larger the forest the more benefit to your acquisition/affinity, but conversely the longer the circuit takes to tend it. WARNING: make sure you tend in earnest rather than simply use this as an automated acquisition for the forests, though patient, will not endure a cynical tending forever. Burning woodlands and defoliated locations in a tending region are much frowned upon.
Once acquired, Sylvanlore will become a permanent part of the ranger's repertoire - but its potency is slightly different to regular skills. Sylvanlore can be learned using lessons, to advance it up the skill levels (like any specialist skill). This permanent learned level is boosted by forest affinity - probably different from one ancient woodland to the next - if it ranks in the top twelve active sylvan specialists. The rank number defines a maximum Sylvanlore the Ranger can use, in a particular location, based on which forest. The affinity points gained in that forest will define the actual boost, e..g. affinity of 6000 would boost Sylvanlore by the equivalent of Competent+50% level on top of the learned SKILLS level.
NOTE: use the "robins" ability in Falconry to judicious place these delightful birds so your affinity-gain is heralded from forest to forest, so each act advances your affinity in not one but many of the ancient woodlands of the realm.