[APWG] Ecosystem Restoration Vegetation survey method validation and limitations Re: 30 toe points can categorize, from horrible to excellent

[Wayne Tyson]

Honorable APWG and Craig:

Please forgive me if this is redundant. I could almost swear that I 
responded to this post earlier, but I can't find such a reply in my email 
records, so I'm presuming that I was dreaming and didn't actually send it 
(or inadvertently deleted it rather than sending it). If you receive two 
emails from me in response to Dremann's email, please post it or send a copy 
to me. Thanks.

I understand that Craig believes that the survey method he cites is 
"adequate to get a good snapshot of what is going on with the weeds and
native plants on a site." But my question was about the basis for that 
belief. That has not been established yet. I also understand that, as 
Dremann implies, knowledge increases with sample size and that there comes a 
point where additional data will no longer significantly improve research 
results. (I agree that when that point is reached, the power of the survey 
method, such as it may be, is close enough to its upper limit to stop 
sampling. That pretty much describes sample size adequacy. However, that 
number might be more or less than any arbitrarily-determined number such as, 
say, 100.)

I am hoping that Craig and/or others will explain the basis for the 
determination that 30 intercepts adequately characterizes the entire 
population being sampled for me and for others who may be interested.

WT

----- Original Message ----- 
From: "Craig Dremann - Redwood City Seed Company" <Craig at astreet.com>
To: <apwg at lists.plantconservation.org>
Sent: Thursday, April 19, 2012 8:06 AM
Subject: [APWG] 30 toe points can categorize, from horrible to excellent


You asked: Upon what basis is "toe-point" method and  "30 paces"
demonstrably "a good snapshot of what is going on?"

The 30 pace toe-point measurement of weeding projects or grassland
restoration project, or for doing a weed/native plant census, 30 paces is
adequate to get a good snapshot of what is going on with the weeds and
native plants on a site.

This quick and easy measurement is not to write a PhD thesis on the plant
community, just to get a snapshot of what is going on, so you can see the
trends when you do a 30 pace toe-point through the same habitat in the
future.   It is also to get yourself sensitive to exactly what species of
weeds and natives are growing there right now.

If you look at the pictures at http://www.ecoseeds.com/WMA.html, like the
solid Harding grass at Cloverdale ranch, or the solid wildflowers at Kite
Hill or the solid native grasses at Shaw and Mark Vande Pol properties,
imagine that you are doing a toe-point through those properties.

So you start your 30 pace toe-point through that Cloverdale ranch six foot
tall solid harding grass, and probably by the tenth step, you start to get
an idea of what the 20th and the 30th and the 100th step may look like.
The same goes for the pictures of Shaw and Mark Vande Pol's solid natives,
or the wildflower field at Kite Hill.

By the tenth step, you start to develop rough percentage of cover of the
weeds, the wildflowers and the native grasses, and by the 30th toe-point
step, you have enough data to know what is going on with the wildflowers,
plus  photos of the wildflowers can confirm your wildflower cover
measurements also.

Another reason that a 30 toe-point measurement is adequate, is that it can
quickly and easily put your site into categories of native cover quality,
Horrible=0-50% native grass/wildflower cover, Poor=51-75%, Good=76-90%,
Excellent=91-99%, As good as it gets in 2012, like at Mark Vande Pol's
place=99.5%.

Sincerely,  Craig Dremann (650) 325-7333



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