The bulk of the book provides information on identifying nearly 500 species from around the world, divided into spore trees, seed trees
, cycads, ginkgos, conifers, and flowering trees, with brief notes on height, type, where each grows, bark, leaf, flower, and fruit.
We learned to choose which trees to cut down, which to girdle, and which to leave to grow into our crop and seed trees
. We learned to judge the lean of a tree, to sever a bended sapling with one stroke of an ax, to pull (not push) a bow saw blade, and to prune branches near the trunk.
New pine generations may become effective seed sources above the present seed trees
and will probably encourage an upward shift of the pine tree limit.
At each study site, Sherman live traps were placed on the ground in the vicinity of 10 to 12 Araucaria seed trees
, arranged so that 2 large (model XLF15) and 3 small (model LFATDG) traps were placed within a tree's seed shadow and a similar group of 5 traps was placed nearby off the seed fall.
The others relied on seed trees
, with site preparation by either burning or mechanical disturbance.'
In this context, the detection of relatives within 50 m of each other, but not 250 m, fits with the height of the seed trees
in this study being on average 25 m.
And Wilkinson's forest management plan rests on some remarkably simple principles: never cut more than your annual growth rate; don't cut all your biggest and oldest tees; and never cut your tallest tree (the tallest tree prompts all others to grow straight up and surpass it); maintain a multiple-height, multiple-age, multiple-species forest; always leave a canopy (has nature been wrong for thousands of years by regenerating under the protection of parent trees?); leave dead wood and debris where it falls; keep your eye out for good seed trees
(let the squirrels and chipmunks show you which cones they prefer to dine on), and let those trees naturally reseed your forest; keep chemicals out of your forest.
Sometime within the next two to three years, I plan to clear-cut that area, leaving some of the low-branched oak trees for seed trees
and wildlife food trees and cutting out the small black ash trees.
"What's going to make the difference is removing the big seed trees
," he says.
Some are marked to be cut, others are spared as seed trees
left to grow until the next cutting cycle.
He has a few favorite trees he will not harvest, preferring to leave them as seed trees
, and he refuses to fell mature hemlock.
According to Gulland, sustainable woodlot management means selective harvesting--thinning dense stands and removing poorer-quality trees--while maintaining the site and soil, and leaving a diversity of seed trees
as well as some standing dead trees for wildlife.