[APWG] Mathematical Constants for annual, biennial weeds and natives

Sat Sep 22 10:33:59 CDT 2012

Mathematical Constants for annual, biennial weeds and natives

For those of us going out in 2013 to manage annual and biennial weeds,
there is a concept that might be useful--Mathematical Constants.

By measuring the interactions between the annual or biennial weeds, and
local native perennial plants, you can assign a number from 1 to 100 for
each species of weed and native plant.  Plants with a rating of <one> are
the weakest weeds, and those with the mathematical constant of 100, are
the most difficult to manage.

Then, like a poker game, you use the local native species that has a
higher mathematical constant number, to permanently replace the weed that
has a lower number than the preferred native.

For example, Yellow star thistle only rates a 5 on the 1-100 scale, which
means that there are a whole lot of native plants that could be planted to
permanently replace that weed.  This concept is especially useful to rate
the invasiveness of weeds, that appear to be spreading rapidly, like
Yellow Star thistle, or cheatgrass.

When you measure their interaction of the weeds vs the local natives, you
may find that weeds like cheatgrass are only default weeds, only growing
where the native cover is absent, and that by planting back any amount of
native cover, can permanently cure those weed problems.

The most valuable use of Mathematical Constants, is to be able to
determine the proper percentage of each species, for example for
replanting after a construction project.  The amount of cover that each
species takes up in ecosystem, produces a mathematical constant.   It is
like making a list of ingredients and amounts of each ingredient, when you
are baking a cake.

A cup of native perennial grasses with a cup of native sunflower family
members, and three tablespoons of native bean family members, etc.

And each species is linked together, like a web.  If you decrease the
percentage cover of  one species, then other species percent cover will
have to increase, but you need to know what those links are, that keep the
ecosystem holding together as one piece of cloth.

And a most interesting and elegant thing, is that those links can be
written as mathematical equations, and then you can use those equations to
write a computer program to predict the ultimate cover of each species,
when you change the percent cover of a single species.   I uncovered the
potential of those mathematical equations almost 20 years ago, while
working on native grasslands here in Central California.

Most ecological restoration projects required by government agencies, like
replanting pipeline right of ways after construction, or replanting gas
well pads, or mine tailings, or new highway construction road sides,
require the contractors to plants natives, and the project specs tell you
to sow X, Y, Z species at so many pounds to the acre.

However, those seed mixed have not been developed using the Mathematical
Constant concept, and they are usually never pre-tested in small scale
test plots to see if they will actually work.

When you use native plants for restoration, it assumes that you want to
permanently replace the weeds in the area with plants that are locally
native.  Over the last 40 years of watching both restoration and weed
projects, there is rarely any small scale test plots planted prior to the
big project, to see if the natives you want to use will really work.

And for the weed projects, planning is almost never done to choose the
local natives you want to grow in the place of the weeds, because we get
so focused on the weeds, instead of looking at and restoring the whole
native ecosystem that we are working in.

I hope that this concept of Mathematical Constants for weeds and native
plants, is useful, and whenever you start a restoration or weeding
project, look for and keep in mind that these interactions exist, and that
they may be used to your benefit, to produce a much better result.

Sincerely,  Craig Dremann (650) 325-7333