Agroforesty and animals

rexs13 rexs13 at open.org
Tue Mar 18 16:37:28 EST 1997


rweinber at orednet.org (Robert G Weinberger) wrote:


>In a previous article, dwheeler at teleport.com () says>
>>In many places in the world, agroforestry is effectively used with native
>>animals. But I question the use of bringing other non-native animals into
>>the ecosystem. This can create long-term consequences, not all of which
>>are good.
>>
>>Consider: In the Pacific Northwest (U.S.) temperate forests, at least 60
>>species of animals are known to consumer and thus distribute mycorrhizal
>>fungi, which are essential adjuncts to forest health. However, frequently
>>raised farm animals such as horses, cows, sheep and pigs are not native
>>to this area and are not known to distribute these fungi (pigs being the
>>exception). In addition, sheep, cows, and horses can cause serious
>>erosion of the soil. This erosion in turn stresses the plants upon which
>>they graze, which further stresses the mycorrhizal fungi associated with
>>these plants. This would seem to create an expanding cycle of stress.
>>
>>Would anyone like to comment on this?
>>
>>Daniel B. Wheeler

>*Carefully managed* grazing by sheep or cattle can often help hold back
>herbaceous vegetation that is in competition with seedlings, allowing good
>juvenile growth without the need to resort to herbicides. I have several
>grazing exclosures in regeneration areas that show 1/5 or less the growth &
>survival as the areas outside the exclosures. Some of these are now 20+
>years old and the ungrazed areas are still well behind. 
>While sheep and cattle may not distribute mycorrhyzal spores, unless the
>level of grazing is excessive, they do little to depress the total level of
>voles and other rodents that are the primary distributers.
>Bob Weinberger
>La Grande, OR

As a long time sheep rancher, I have to agree with Bob. Proper
management practices need to be employed when livestock is grazed or
used to control weeds. Over-grazing an area will stress most crops and
soils not to mention the livestock.

As a truffle collector and propagator, I would like to see more
research into this area. I have found large naturally occurring
populations of truffes in areas that are pastured by livestock. I am
not sure wether (sheep pun;-) or not this is due to the livestock or
that the only favorable area for the truffles to grow just happened to
be where trees were located in the lower-elevation (compared to the
surrounding timber stands) pasture.

I do know of areas where the USFS conducted a grazing program in the
Coast Range west of Corvallis about 8 years ago. I wonder if any myco
studies have been conducted there to see if an impact was made?

Rex Swartzendruber




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