"Assessing and Understanding Trail Degradation: Results fromBig South Fork National River and Recreation Area"

Mike Vandeman wrote:
Dear Dr. Marion:

I just finished reading your paper, "Assessing and Understanding Trail
Degradation: Results from Big South Fork National River and Recreation
Area". It was advertized by IMBA (unjustifiably) as support for
mountain biking. You may find the attached paper of interest. Please
pay particular attention to the analysis of Wilson & Seney and
Thurston and Reader. Their conclusions don't follow from their data,
so they should not be taken at face value.

Your paper is useful for drawing attention to the way trails are
harmed. But it is not the best design for drawing some of the
distinctions you make. For example, to compare types of use, you need
to create an experimental design, not a survey design. And you need to
control for all major confounding factors. For example, to compare
hiking with mountain biking, you need to apply both treatments to
identical soils on either the same trail, or very similar trails, and
measure before and after. You compared hikers and mountain bikers on
completely different trails! So the differences found could be due to
the differences in the trails or soils, the weather during use, or the
past amount of traffic. After applying typical hiking and mountain
biking treatments to identical soils under identical conditions, you
would be able to compare their impacts. You also made the same error
that all other researchers have made: ignoring distance travelled. If
(let's suppose) hikers and mountain bikers caused the same erosion PER
FOOT (which is what you measured), you have to multiply by typical
distances travelled, to get the total per-user impact. Mountain bikers
travel several times as far as hikers, and thus have several times the
impact.

You also threw away data (cross sectional area of erosion), converting
measured area to binary (on/off) data. I understand that you had
limited time & resources, but I think it would be better to use all
the data you can get.

It is better to use all the data you can get, but you have to draw the
line somewhere. Otherwise you would end up testing every section of
every trail in the world which is clearly unrealistic, and the amount of
data would be unmanageable. Raw data also ends up in different forms and
has different extents so it needs to be manipulated into a more basic
form in order to make an equal analysis. This is where binary excels.
Where it falls down is the extent of damage, but so long as the author
is explicit about the extent to which their investigation is valid, this
is not an issue.

You also accept without question that all forms of recreation are
acceptable. That decision is up to the politicians, and is not
supported -- or supportable -- by science. All options should remain
on the table, including banning mountain bikes and other ORVs, as well
as horses. Mountain bikes and other ORVs are machines, and have no
right to be on trails

You have to make assumptions and to give all recreational equal status
at the start of the investigation removes all bias that might exist.
This gives the study credibility for starting out as impartial. The
purpose is to establish if any activity is worse than any other, not to
prove that one is worse. You start from a conclusion and try to prove
it. Credible scientists start with equality and draw conclusions based
on their findings. You don;t operate like that, and this is partly why
you lack credibility....

Horses are exotic
species, but arguably have a right to be here because their genus
evolved in North America. However, when they are being used as
vehicles, they undoubtedly have much greater impacts. The best way to
ensure equal access (the essence of our democracy) is to ban all
vehicles from the trails, including animals used as vehicles.

Wrong. The best way to ensure equal access is to let everybody have
access rather than to ban vehicles. Because banning vehicles and
permitting people is not equal. It is biased against vehicles. Use
freedom of speach as the example by which to compare. It would not be
practicable to let all "vehicles" (as you define them) onto trails, but
your statement is incorrect.

I understand that you had time- and resources constraints, but I would
like to encourage you to do an experimental study, if you want to draw
defensible conclusions.

Sincerely,

Mike Vandeman

We'll just snip your "experimental study" Mike, because as we all know
from having read it, it is not experimental, it is a selective
literature review, carefully designed to prove your point. At no point
do you attempt to prove yourself wrong (the basis of all good scientific
research). If you are right as you claim to be, you should have no
problems attempting to prove yourself wrong and documenting that as
such. So in conclusion, Dr Marion has conducted a scientific study and
admitted to the failings of the study. Vandeman is flawless, the perfect
scientist. Go on Mike, find a cure for cancer if you are so great!

And lets not cross post to multiple newsgroups, you know that it is rude.