[permaculture] Edges - Re: permaculture and science

Rich Blaha rich at mossbackfarm.com
Sat Feb 3 14:56:43 EST 2007


As Robyn mentions, the 'Edge Effect' is a long standing ecological term.  Interestingly enough, many in the conservation biology field have a negative view of this phenomenon in its effect upon sensitive species.  

In my work in both Tallgrass Prairie and northwestern US Old growth forests, the fragmentation of habitat allows for invasion of these habitats by 'generalist' species, generally to the detriment of a habitat specialist species.  In forests, increased edge increases the habitat for Marbled Murrelet nest predators, such as Crows, Ravens, and Jays.  In prairies, the edge increases habitat for nest parasites like Cowbirds.

An edge is considered ecologically productive because it is a location that can tap into the resources of 2 different environments.  The shade, coolness, fungal diversity, and biomass of the forest; and the sunlight, fossorial rodents, and nitrogen fixation of the meadow, for example.  

Or to use the shoreline example, the coastal headlands, with their moisture and milder climate than inland locations;  and the nearshore ocean, with its seawood and plankton production.  Add the destructive power of waves, which bring forth a bounty of dead and dying flotsam with each tidal cycle, and sloughs and brackish water (an edge habitat unto itself), which harbor an entirely different, and very productive, ecosystem.

As habitat generalists, humans' preference for edges allows us to tap into the productive capacity of ecotonal environments (a la the forest garden).  It's just nice to have options....

Cheers

Rich
Mossback Farm
www.mossbackfarm.com/journal


>   
>     4. Edges - Re: permaculture and science (Rich Morris)
>     5. Re: Edges - Re: permaculture and science (Lawrence F. London, Jr.)

>     7. Re: Edges - Re: permaculture and science (Robyn Francis)

>  
>  

>  ------------------------------
>  
>  Message: 4
>  Date: Fri, 02 Feb 2007 20:01:00 +0000
>  From: Rich Morris <webmaster at pfaf.org>
>  Subject: [permaculture] Edges - Re: permaculture and science
>  To: permaculture at lists.ibiblio.org
>  Message-ID: <45C3987C.1040500 at pfaf.org>
>  Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>  
>  The discussion on permaculture and science got me thinking about some of
>  the hypothesis of permaculture and whether they are testable, and this
>  was brought to mind in a recent comment on
>  http://en.wikipedia.org/wiki/Talk:Permaculture
>  
>  "Sure, coastal areas are more full of life, there's rainfall,
>  temperatures are moderate, but to jump to the conclusion that "edges"
>  are valuable from that seems a stretch. Please provide more evidence, at
>  least in the form of links or delete! Even if there is an advantage to
>  the seashore, the coastal edge is tens of miles wide, while I've seen
>  permaculture designs where there were edges every hundred feet or so, it
>  might not scale down. Permaculture is an essential idea, so it becomes
>  even more important that it doesn't get watered down by New Age
>  superstitions."
>  
>  Theres quite a few places in the permaculture literature where there are
>  claims that edges are the most productive/most diverse. Is their any
>  evidence to support these claims?
>  
>  Rich
>  
>  --
>  Plants for a Future: 7000 useful plants
>  Web:   http://www.pfaf.org/
>  Post:  1 Lerryn View, Lerryn, Lostwithiel, Cornwall, PL22 0QJ
>  Tel:     01208 872 963
>  Email: webweaver at pfaf.org
>  PFAF electronic mailing list http://groups.yahoo.com/group/pfaf
>  
>  
>  
>  ------------------------------
>  
>  Message: 5
>  Date: Fri, 02 Feb 2007 15:12:34 -0500
>  From: "Lawrence F. London, Jr." <lfl at intrex.net>
>  Subject: Re: [permaculture] Edges - Re: permaculture and science
>  To: permaculture <permaculture at lists.ibiblio.org>
>  Message-ID: <45C39B32.2000802 at intrex.net>
>  Content-Type: text/plain; charset=us-ascii; format=flowed
>  
>  Rich Morris wrote:
>  
>  > The discussion on permaculture and science got me thinking about some of
>  > the hypothesis of permaculture and whether they are testable, and this
>  > was brought to mind in a recent comment on
>  > 	 http://en.wikipedia.org/wiki/Talk:Permaculture
>  >
>  > "Sure, coastal areas are more full of life, there's rainfall,
>  > temperatures are moderate, but to jump to the conclusion that "edges"
>  > are valuable from that seems a stretch. Please provide more evidence, at
>  > least in the form of links or delete! Even if there is an advantage to
>  > the seashore, the coastal edge is tens of miles wide, while I've seen
>  > permaculture designs where there were edges every hundred feet or so, it
>  > might not scale down. Permaculture is an essential idea, so it becomes
>  > even more important that it doesn't get watered down by New Age
>  > superstitions."
>  >
>  > Theres quite a few places in the permaculture literature where there are
>  > claims that edges are the most productive/most diverse. Is their any
>  > evidence to support these claims?
>  
>  Marine estuaries are edge zones. How important are they? Very, as they
>  provide in some cases the only breeding ground available to many marine organisms.
>  Include in that rivers that merge with sounds and then the ocean.
>  Fish swim upstream to breed. So the distinction gets blurred, river as edge zone,
>  but in the context of one of the most important functions of edge zones, habitat
>  for breeding, it qualifies.
>  --
>  Lawrence F. London, Jr.
>  Venaura Farm
>  lfl at intrex.net
>  http://market-farming.com
>  http://market-farming.com/venaurafarm
>  http://venaurafarm.blogspot.com/
>  http://www.ibiblio.org/ecolandtech
>  
>  
>  

>  Message: 7
>  Date: Sat, 03 Feb 2007 09:52:08 +1100
>  From: Robyn Francis <erda at nor.com.au>
>  Subject: Re: [permaculture] Edges - Re: permaculture and science
>  To: permaculture <permaculture at lists.ibiblio.org>
>  Message-ID: <C1EA0BC8.27B1%erda at nor.com.au>
>  Content-Type: text/plain;	 charset="US-ASCII"
>  
>  Edge effect is not a permaculture invention or new age superstition, it's a
>  recognised phenomena in the science of ecology--the technical term is an
>  ecotone. Whereas ecologists simply observe and record the diversity and
>  productivity of naturally occurring edges, permaculture takes it a step
>  further and consciously builds it beneficially into design. Many of the
>  common production-system edges employed in permaculture can be found in
>  traditional and indigenous systems.
>  
>  And everything is relative, oceans and landmass are big systems with big
>  edges, smaller systems will have smaller ecotones. This starts to get into
>  the arena of fractals and patterning, the understanding of which is
>  intrinsic to good design.
>  
>  Ciao
>  Robyn
>  
>  
>  On 3/2/07 7:01 AM, "Rich Morris" <webmaster at pfaf.org> wrote:
>  
>  > The discussion on permaculture and science got me thinking about some of
>  > the hypothesis of permaculture and whether they are testable, and this
>  > was brought to mind in a recent comment on
>  > http://en.wikipedia.org/wiki/Talk:Permaculture
>  >
>  > "Sure, coastal areas are more full of life, there's rainfall,
>  > temperatures are moderate, but to jump to the conclusion that "edges"
>  > are valuable from that seems a stretch. Please provide more evidence, at
>  > least in the form of links or delete! Even if there is an advantage to
>  > the seashore, the coastal edge is tens of miles wide, while I've seen
>  > permaculture designs where there were edges every hundred feet or so, it
>  > might not scale down. Permaculture is an essential idea, so it becomes
>  > even more important that it doesn't get watered down by New Age
>  > superstitions."
>  >
>  > Theres quite a few places in the permaculture literature where there are
>  > claims that edges are the most productive/most diverse. Is their any
>  > evidence to support these claims?
>  >
>  > Rich
>  
>  
>  
>  



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