M
Mike Vandeman
Guest
The Impacts of Mountain Biking on Wildlife and People
Michael J. Vandeman, Ph.D.
March 27, 2007
It is obvious that mountain biking is harmful to some wildlife and
people. No one denies that. Bikes create V-shaped ruts in trails,
throw dirt to the outside on turns, crush small plants and animals on
and under the trail, increase levels of human access into wildlife
habitat, drive other trail users off the trails and out of the parks,
and teach young people that the rough treatment of nature is
acceptable. Because land managers were starting to ban bikes from
trails, mountain bikers decided to try to shift the battlefield to
science, and try to convince people that mountain biking is no more
harmful than hiking.
The appropriate tool for comparing the impacts of two activities, such
as hiking and mountain biking, is the experimental study. One selects
two trails, as identical as possible, and applies hiking to one and
mountain biking to the other, and then measures the variable of
interest (e.g. erosion), while trying to control all other factors
(e.g. the weather). IMBA has collected all the research they could
find that seemed favorable to mountain biking (see
http://www.imba.com/resources/science/index.html). I reviewed that
research, and one other experimental study (see
http://home.pacbell.net/mjvande/scb7). While the authors claimed to
show that mountain biking and hiking have the same impacts, they
didn't report their results accurately.
For example, they said that both activities caused the same amount of
erosion, but they forgot to multiply the amount of erosion by the
total distance traveled (mountain bikers typically travel several
times as far as hikers, thus causing several times as much erosion).
Some other defects that biased their conclusions are: riding much more
gently than normal mountain biking; not measuring soil displaced
sideways; and ignoring research or results unfavorable to mountain
biking. One researcher even told the hikers to approach desert bighorn
sheep, while instructing the bikers to ride by without stopping! A
study (by M. J. Wisdom, et al) that found mountain biking to have
greater impacts on elk than hiking has been ignored by IMBA.
D. D. White et al did a "survey" study (reviewed at
http://home.pacbell.net/mjvande/white) which claimed that mountain
biking has the same impacts on soil as hiking. A survey study simply
takes measurements of existing conditions, and tries to draw
inferences from them. For example, one might measure tread depth on
hiking trails and compare it with that on mountain biking trails.
Nothing useful can be concluded from such a study: there's no way to
know if the differences were due to hiking vs. biking, or to
differences in terrain, weather, soil type, amount of use, trail
construction or maintenance, hikers walking on the "bike" trails,
bikers poaching the hiking trails, etc.! White collected no data on
hiking, but used figures from other parts of the world! Jeff Marion's
research (reviewed at http://home.pacbell.net/mjvande/marion) is
likewise based on a survey design, and thus of no value in such
comparisons.
There is a trend for advocates of mountain biking to publish articles
on mountain biking impacts that purport to be scientific studies, but
in fact are designed and intended to promote mountain biking by
minimizing its impacts and by drawing conclusions that don't follow
from their data. The danger is that people will quote such conclusions
out of context, as if they were supported by the research, which they
are not.
===
I am working on creating wildlife habitat that is off-limits to
humans ("pure habitat"). Want to help? (I spent the previous 8
years fighting auto dependence and road construction.)
Please don't put a cell phone next to any part of your body that you are fond of!
http://home.pacbell.net/mjvande
Michael J. Vandeman, Ph.D.
March 27, 2007
It is obvious that mountain biking is harmful to some wildlife and
people. No one denies that. Bikes create V-shaped ruts in trails,
throw dirt to the outside on turns, crush small plants and animals on
and under the trail, increase levels of human access into wildlife
habitat, drive other trail users off the trails and out of the parks,
and teach young people that the rough treatment of nature is
acceptable. Because land managers were starting to ban bikes from
trails, mountain bikers decided to try to shift the battlefield to
science, and try to convince people that mountain biking is no more
harmful than hiking.
The appropriate tool for comparing the impacts of two activities, such
as hiking and mountain biking, is the experimental study. One selects
two trails, as identical as possible, and applies hiking to one and
mountain biking to the other, and then measures the variable of
interest (e.g. erosion), while trying to control all other factors
(e.g. the weather). IMBA has collected all the research they could
find that seemed favorable to mountain biking (see
http://www.imba.com/resources/science/index.html). I reviewed that
research, and one other experimental study (see
http://home.pacbell.net/mjvande/scb7). While the authors claimed to
show that mountain biking and hiking have the same impacts, they
didn't report their results accurately.
For example, they said that both activities caused the same amount of
erosion, but they forgot to multiply the amount of erosion by the
total distance traveled (mountain bikers typically travel several
times as far as hikers, thus causing several times as much erosion).
Some other defects that biased their conclusions are: riding much more
gently than normal mountain biking; not measuring soil displaced
sideways; and ignoring research or results unfavorable to mountain
biking. One researcher even told the hikers to approach desert bighorn
sheep, while instructing the bikers to ride by without stopping! A
study (by M. J. Wisdom, et al) that found mountain biking to have
greater impacts on elk than hiking has been ignored by IMBA.
D. D. White et al did a "survey" study (reviewed at
http://home.pacbell.net/mjvande/white) which claimed that mountain
biking has the same impacts on soil as hiking. A survey study simply
takes measurements of existing conditions, and tries to draw
inferences from them. For example, one might measure tread depth on
hiking trails and compare it with that on mountain biking trails.
Nothing useful can be concluded from such a study: there's no way to
know if the differences were due to hiking vs. biking, or to
differences in terrain, weather, soil type, amount of use, trail
construction or maintenance, hikers walking on the "bike" trails,
bikers poaching the hiking trails, etc.! White collected no data on
hiking, but used figures from other parts of the world! Jeff Marion's
research (reviewed at http://home.pacbell.net/mjvande/marion) is
likewise based on a survey design, and thus of no value in such
comparisons.
There is a trend for advocates of mountain biking to publish articles
on mountain biking impacts that purport to be scientific studies, but
in fact are designed and intended to promote mountain biking by
minimizing its impacts and by drawing conclusions that don't follow
from their data. The danger is that people will quote such conclusions
out of context, as if they were supported by the research, which they
are not.
===
I am working on creating wildlife habitat that is off-limits to
humans ("pure habitat"). Want to help? (I spent the previous 8
years fighting auto dependence and road construction.)
Please don't put a cell phone next to any part of your body that you are fond of!
http://home.pacbell.net/mjvande