Some ideas for forestry projects (arborial ethicists beware):
<1> Attach thin vibrating wires to the branches of two oppositely-growing trees. As the wires are stretched due to natural tree growth – or given slack – the wind blowing across them will produce different notes. A tree that began as, say, C-major will become B-flat. This could be done to a variety of trees, using a variety of wires of various lengths and thicknesses, so as to produce an acres-wide arborial instrument which never ceases to change its drone.
<2> Attach a large stone to a system of ropes and pulleys. Attach the other ends of these ropes and pulleys to the branches of growing trees, and then again, onward, to the branches of other growing trees. As the branches grow, if the force has been correctly distributed, the stone will be lifted off the ground.
<2a> Once the stone leaves the ground, another, secondary, mechanical process could come into effect: say a turning wheel that tightens and/or otherwise alters the positions of the original ropes and pulleys.
<2b> This could start-off further mechanical processes – perhaps a bag of seeds is upended and, a dozen years later, new trees grow, entering the system.
<3> Plant a new grove using only one tree species, and rope the branches of all the trees together according to a carefully architected pattern. Return over the years as the trees grow to tighten the ropes, pulling and bending the branches into their desired shape or mold. Eventually the trees will form a complicated network of hallways whose canopies are interlaced branches. Domes, arches, etc., could all be created.
[Images from Pruned].
<4> A rope is attached to the top of a newly-planted tree. The other end of the rope is attached to a complex spring-and-coil machine that includes within it a pre-sharpened axe. The axe is attached to a long handle, a handle whose length is the exact distance between the machine and the tree. Further, the axe is only barely restrained from swinging by a small lever. Once the tree, several years on, has reached a certain height, the rope’s tension triggers the machine, lifting that small lever, and the axe swings round, burying itself into the tree’s trunk: killing – perhaps felling – the tree.