permaculture

[Alia Tsang <alia@dietrick.org>]

This article was interesting (though I'm still working on digesting
it). It suggests that the offspring of plants that have been growing
in a diverse setting for generations (8 years in this experiment) are
more productive (as measured by above ground biomass) than plants that
have been growing for generations in monoculture. The probable
mechanism is greater niche differentiation, or specialization, which
reduces competition. The implications for plant breeding could be
interesting to think about. Would experiments on intercropping, for
example, show even greater benefits if the plant varieties tested were
bred in an diverse ecosystem rather than monoculture? Are standard
garden catalog variety seeds suitable genetics for permaculture?

The study doesn't look at what's going on belowground, unfortunately.
(And they used a really artificial agricultural soil + sand + perlite
mix to test the plants on.)

Article link and abstract below, I can send a PDF to anyone interested.

Alia

Selection for niche differentiation in plant communities increases
biodiversity effects
http://www.nature.com/nature/journal/v515/n7525/full/nature13869.html

In experimental plant communities, relationships between biodiversity
and ecosystem functioning have been found to strengthen over time1, 2,
a fact often attributed to increased resource complementarity between
species in mixtures3 and negative plant–soil feedbacks in
monocultures4. Here we show that selection for niche differentiation
between species can drive this increasing biodiversity effect. Growing
12 grassland species in test monocultures and mixtures, we found
character displacement between species and increased biodiversity
effects when plants had been selected over 8 years in species mixtures
rather than in monocultures. When grown in mixtures, relative
differences in height and specific leaf area between plant species
selected in mixtures (mixture types) were greater than between species
selected in monocultures (monoculture types). Furthermore, net
biodiversity and complementarity effects1, 2 were greater in mixtures
of mixture types than in mixtures of monoculture types. Our study
demonstrates a novel mechanism for the increase in biodiversity
effects: selection for increased niche differentiation through
character displacement. Selection in diverse mixtures may therefore
increase species coexistence and ecosystem functioning in natural
communities and may also allow increased mixture yields in agriculture
or forestry. However, loss of biodiversity and prolonged selection of
crops in monoculture may compromise this potential for selection in
the longer term.