Posted by
Jochen Fromm-3 on
URL: http://friam.383.s1.nabble.com/Diversity-and-Stability-in-Food-Webs-tp520801.html
Does increasing diversity affect the stability in
ecosystems and food-webs? If so, is the effect positive
or negative, i.e. does increasing diversity lead to
stability or fragility of the system ? Common sense
says that systems with low diversity (for instance artificial
monocultures) have low stability and are vulnerable
to parasites, infections and diseases.
Yet does declining diversity ultimately lead to reductions
in food-chain length and ecosystem stability ? The relation
between diversity, food-chain length and ecological processes
seens to be complex. Ecosystems do not contain only linear
food-chains, they consist of complex recurrent food-webs.
If I remember it correctly, even in simple Lotka-Volterra
equations with more than 2 dimensions chaotic structures can
arise (in 2 dimensions with 2 species there is the usual
predator-prey limit cycle, but in 3 dimensions there are
also strange attractors possible. I have read it somewhere,
but I can't remember where).
Insights in this ongoing diversity-stability debate
could be useful, because consumer-producer or
predator-prey relations can be found in many complex
systems. The SFI has an interesting site with
many links about it at
http://discuss.santafe.edu/paleofoodwebs/for example the following:
(a)
The diversity-stability debate
Kevin Shear McCann, Nature 405 (2000) 228-233
http://discuss.santafe.edu/files/paleofoodwebs/McCann2000Nature.pdf(b)
The long and short of food-chain length
David M. Post, Trends in Ecology & Evolution Vol.17 No.6 June (2002) 269-277
http://discuss.santafe.edu/files/paleofoodwebs/Post2002TREE.pdf(c)
Stability in Real Food Webs: Weak Links in Long Loops
Anje-Margriet Neutel et al., Science 296 (2002) 1120-1123
http://discuss.santafe.edu/files/paleofoodwebs/Neuteletal2002Science.pdf(a) is a nice review, (b) argues that the food-chain length is
influenced by many factors, ecosystem size and age, degree of
ecological isolation, natural resource availability, and
predator-prey interactions, and (c) says that "trophic loops",
i.e. closed food-chains, add stability to the system, esp.
the particularly long ones which contain many weak links.
They found that "loop weights" of the longer loops were low
in real systems.
-J.