[permaculture] "thirsty " trees....

Kirby Fry peace at totalaccess.net
Tue Sep 3 08:59:31 EDT 2002


Hi Mark,

Just dug up some interesting snippets from the Pc design manual...

p.435, "Many [perennial grasslands], in fact are treeless areas established
during periods of icecap retreat, and have never established as forests,
although both soils and climactic factors will permit forest establishment.
Other grasslands are maintained by fire (natural, from lightning strikes; or
managed from human interference) against forest invasion."

p.435, "while a forest may have a visible "standing crop' of 207 t/ha, and
grasses only 7 t/ha, below the ground forests produce 184 t/ha of organic
matter to the 345 t/ha of natural prairie in equivalent soil / climate
regimes (Foth, 1984, based on other studies).

p. 142, "The composition of the atmosphere is the result of reactive
processes, and forests may be doing about 80% of the work, with the rest due
to oceanic or aquatic exchange."

Lots of room in their to fill in the blanks, but helps to provide some actul
numbers.


Kirby





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