[APWG] Percentage cover of each species to find constants

[Craig Dremann - Redwood City Seed Company]

Dear Wayne and All,

I apologize if you thought I was not answering your questions-- I will try
and elaborate further in this email.

WAYNE: I do think of the whole earth as a huge Petri dish, but I cannot
understand
what you are talking about. I asked "What ecological condition(s) are
revealed by cover?"

CRAIG:  The whole world is a giant petri dish, because all teresstrial
life is closely confined in an extremely thin layer on the planet.  If we
shrank the planet to the size of a petri dish, all life would be a layer
about 30 millionths of an inch thick.

In terms of plant interactions, if you think of the local ecosystem you
are working within, as one big giant petri dish, then the plant
interactions become more readily evident.   The ecological conditions
revealed by cover--cover is what shows you the interactions between the
two species of native plants, or between the native plants and the weeds.

What is seen on a regular petri dish is the battle between a pathogen and
an antibiotic, and this battle is played out on a macroscopic scale in the
ecosystem cover interactions.  Every terrestrial non-riparian plant as it
grows, gives off natural herbicides in greater or lesser amounts and
potencies, that act like antibiotics.

You can do experiments by adding native seeds as an antibiotic to a weed
patch, such as California poppy seeds.  Or add fertilizers to benefit your
preferred antibiotic/herbicide/allelopathy-producing plants, to change the
species composition of the weed cover.  You can then use cover to measure
the changes you made by adding the natives or the fertilizers, and you can
see some of those results  at http://www.ecoseeds.com/arastradero.html

I am translating from the microscopic scale--what I have been working on
for almost 20 years--to the macroscopic scale.  In my petri dishes that my
lab cultures pathogens and then uses to discover new plant antibiotics
against pathogens like MRSA, we measure the zone diameters of the
antibiotics killing the pathogens, that you can see at
http://www.ecoseeds.com/mrsa.html.

The same thing happens on the macroscopic scale, where one plant inhibits
another--we just have not gone out yet to measure the battle that is going
on out there each year, just like the pathogens and the antibiotics in the
petri dish.

WAYNE: Do you think that ecological conditions that give rise to
ecological phenomena are not important to the subject at hand?

CRAIG: Cover measurements, especially when done on a very fine scale, is
your very best tool to measure plant interactions.  When I do a transect,
I measure every single species, even if it is only a single plant within a
100 foot long transect.

WAYNE:  Please preserve the string of relevant emails in the future; I'll
greatly appreciate not having to hunt up previous emails to recall the
context and issues under discussion. Thank you.

CRAIG: Sure.

Sincerely,  Craig Dremann (650) 325-7333