Spar trees? LOL, you Brits and your spar trees. So, leaving the top alone is worse for the habitat?
Sacrifices to the tree gods
if you do leave them on top of the wheel, they end up underneath the wheel.Spar tree is a yank term, its the tree that holds the skyline cable in the air. the tail spar is the tree the skyline is terminated / tied off too.
Leaving the top on would mean it continues to broadcast seed over a wide area, not really what you want when your trying to remove the invasive species from a nature reserve.
I wasn't trying to show off by using the latin name, BTW, I simply couldn't remember what the tree was called in english.

sort of - The ground we are working on is ancient peat bog. Traditionally bogs were drained and planted, but they found that lots of rare species were loosing their habitat as a result. The trees dry out the bog, and its usually your pioneer species that cover the ground Common BirchBetula pendula, and Scots pine Pinus sylvestris