permaculture

["T Remiarz" <tomasremiarz@cooptel.net>]

> so here is my question... why would global warming lead to increased
> desertification and a benefit to grasses. in my bioregion Douglas firs
> have evidence in the fossil record 50 million years, to the triassic and
> confirmed fossils are found in navada in the eocene... which was warm and
> wet and tropical...
>
> I guess i don't see how warming will do what this article says...
>
> -j

what the article actually says is:


>> "Long-life plants, such as trees and shrubs, did not show significant
>> shifts, whereas short-life species, such as herbs,
>> showed a strong upward shift," he said.
>>
>> "Herbs, by having a short life cycle, have had several generations
>> during
>> a decade that allows for a faster dispersal of
>> seeds.

there are (at least) two posible explanations for this difference
- trees react slower to temperature changes and therefore move slower
- trees are less affected by temperature changes, and therefore move
little or hardly at all

the timescale of this study has obviously not allowed for a  conclusive
answer to which of the two is correct, or if something else entirely is
going on.

what may be happening is a change in the woodland ground flora, while the
canopy remains relatively stable. that said, there has been a shift in
british woodlands with beech moving further north, which is only partly
related to them being planted where they wouldn't have occured naturally.
still that would represent a change canopy composition rather than a
wholesale change in ecosystem type.

best
tomas

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Tomas Remiarz - GreenLand Services

Ecological Restoration
Woodland Creation and Management
Permaculture Design and Practice