tabeles wrote:
> There is one dimension that is not being fully considered here, the element of
> time. We are very used to flipping a light switch and curing the dark, taking a
> pill and curing the headache and investing in a stock and seeing it gain over
> night.
I am reminded of the Ralph Lentz farm which I recently had the great good fortune
to visit while speaking in Minnesota. What a goldmine. The context was
livestock:watercourse interactions (one of my research areas). Ralph had fenced
off one-third of his pasture stream 30 years ago (as recommended by his natural
resource people of the day, and is still being recommended and even imposed by
threat today in Ontario and elsewhere). He managed the rest with rotational
grazing. Of the latter, he fenced off a portion and set up exclusionary fencing 2
years ago, while continuing rotational grazing on the remainder.
Now, which of the three sections of the stream (30 years exclusion; 28 years
rotational grazing followed by 2 years exclusion; rotational grazing for 30 years)
would you expect to show the healthiest riparian zone (by scientifically measured
criteria)? If you voted for the first one, you'd be dead wrong. What happened
was that excluding both large ungulates and fire (natural vegetation forming
factors in Minnesota and in much of the Great Lakes Basin) produced what Lentz
called an "unnatural succession" - a fully treed riparian zone. The trees were so
tall and vigorous that they fully shaded the ground, leaving almost no herbaceous
vegetation to protect the streambank. As a result, the streambank had caved (and
was caving) in, trees were falling in and accumulating in logjams downstreams, and
the watercourse was wide, shallow, and slow. Measurements of biodiversity by Fish
and Wildlife and U of Minn personnel clearly showed the inadvisability of this
strategy - which is still being forced on farmers even to this day.
Conversely, the 30 year rotational section boasted a stream that was narrow, deep,
and fast flowing with fully vegetated stream edges - because he controlled
grazing. The key is to regulate grazing pressure, which is not that hard in this
region because stock typically prefer upland over riparian vegetation and only go
down to graze near the water when the upland is depleted (this is the opposite of
arid zone experience, but remember, we are in a humid temperate zone where water
is nonlimiting most of the time).
But getting back to Abeles point, the 2 year exclusion zone looked great, with
heavily vegetated banks and lovely young saplings - over 10' high in just two
years. A snapshot of just this section would have clearly reinforced the current
vogue for exclusionary fencing, but just downstream is the evidence of what time -
30 years - does to reverse and indeed override the short term benefit.
I have no doubt that if GE crop and microbe releases are allowed to continue, we
will see a similar pattern - short term "benefit" (such as it is, although even
this is not clearly evident) followed by longer term problems that are clearly
anticipatable with today's knowledge. But like the ill-informed (but not
ill-intentioned) conservation staffers pushing exclusionary fencing today, we
refuse to "see" the future until it stares us in the face. Unnatural succession -
a worthy analogy for contemporary GE technology. Ann
To Unsubscribe: Email majordomo@ces.ncsu.edu with the command
"unsubscribe sanet-mg". If you receive the digest format, use the command
"unsubscribe sanet-mg-digest".
To Subscribe to Digest: Email majordomo@ces.ncsu.edu with the command
"subscribe sanet-mg-digest".
All messages to sanet-mg are archived at:
http://www.sare.org/htdocs/hypermail