On Sun, 08 Aug 2004 07:58:01 -0600, Paul Cassel <[email hidden]> wrote:
..Mike Vandeman wrote:
..
..
..> .
..> .> The tell-tale signs are a body broken in
..> .> two places, separated by the width of a mountain bike tire.
..> .> ===
..> .
..> .Now that's funny. If you really think a bicycle tire will *cut* a snake,
..> .either you're dreaming or you must think bicycles run on razor sharp
..> .tires.
..>
..> Where do you see the word "cut", dumdum????
..
..How else can a snake get into two pieces ('separated' is your
..description) if not by a cut?
Learn to READ. The body is broken in two places, WHICH (THE PLACES) ARE
SEPARATED BY THE WIDTH OF A MOUNTAIN BIKE TIRE. DUH!
..>
..> Hmm, maybe you're thinking of those Jello brand snakes instead. I
..> .doubt a snake would be even killed if run over by a bike.
..>
..> Now you are LYING. Most snakes aren't very big, and are easily killed by being
..> run over.
..
..How do you know? I have seen snakes run over by pickups and large cars
..just wiggle off. I can't say if they're mortally wounded, but they don't
..appear so. The psi of a mtn bike is much smaller.
They may wriggle off, but with a broken spine & other internal organs.
..Now can a snake be killed by a bike? Maybe, but YOU SAID the body would
..be broken. That's plain silly. Examining a car killed snake shows no
..wheel tracks.
..
..Finally, I don't see snakes hanging around most paths. Sure they may be
..sunning themselves on some rocks, but if crossing a trail, they cross
..and get back into cover.
They like to sun themselves.
..> Then you are blind. It is easy for anyone with their eyes open to see
..> bike-caused erosion. Knobby tires are designed to rip up the soil, preparing it
..> to be washed away by the next rain. Without bikes, there is hardly any erosion.
..
..Sure, I go out there and find tire tracks and skid marks, but these
..aren't precursors to erosion because bikers don't take identical tracks.
..So one bike makes a groove, the next one makes an offset groove which
..fills in the previous groove. At least 95% of the trail isn't grooved at
..all because the bikes are just moving along.
All of that grooving loosens the soil, so that the rain can carry it away. Bikes
also throw the soil to one side.
..Now if you want to worry a sport, I think horses make more cuts than
..bikes, but like bikes, the horses don't step in each others' footprints
..so the damage isn't severe. Nor do I blame horses for damaging trails.
..
..Are you confusing MX bikes with engines and mtn bikers? MX motorized
..bikes can do a lot of damage because they sport about 40 hp (the big
..ones) so are banned from wilderness trails. However, my guess is a human
..can do about 1/4 hp so the resulting damage isn't too much even if the
..biker is trying.
Anyone who has seen mountain bike tracks has seen skid marks and dirt thrown to
one side of the trail (erosion). They may do less damage per mile, but because
there are a lot more mountain bikers, they do more total damage.
..I would be with you here if I found any of the damage you claim bikes do
..to wilderness areas. What we have here and what I saw in other places,
..are culture clashes. Each group, hikers, bikers and horsemen wish the
..trail for themselves. They also consider themselves the aesthetically
..superior group so blame damage on the others.
Don't change the subject. It won't help you.
..The greatest damage to the wilderness is the trail itself. Once you have
..that trail and the human incursion, it makes zero difference whether the
.. humans arrive on foot, bike or horse. Blaming bikes for damage more
..than other groups is factually incorrect.
I guess you haven't read the science on the subject, as I have. Or misunderstood
it. See:
The Impacts of Mountain Biking on Wildlife and People --
A Review of the Literature
Michael J. Vandeman, Ph.D.
July 3, 2004
"Every recreationist -- whether hiker, biker, horsepacker, or posey sniffer --
should not begin by asking, 'What's best for ME?' but rather 'What's best for
the bears?'" Tom Butler
"Will we keep some parts of the American landscape natural and wild and free --
or must every acre be easily accessible to people and their toys? … Mountain
bikes' impacts on the land are large and getting worse. … The aggressive push of
mountain bike organizations to build ever-growing webs of trails poses serious
problems of habitat fragmentation, increased erosion, and wildlife conflicts.
As interest in extreme riding continues to grow, as trail networks
burgeon, and as new technology makes it possible for ever-more mountain
bicyclists to participate, even the most remote wild landscapes may become
trammeled -- and trampled -- by knobby tires. … The destruction of wilderness
and the fragmentation of habitats and ecosystems is death by a thousand cuts.
Will introduction of mountain bikes -- and their penetration farther into
wilderness -- promote additional fragmentation and human conflicts with the
natural world? Yes." Brian O'Donnell and Michael Carroll
"Some things are obvious: mountain bikes do more damage to the land than hikers.
To think otherwise ignores the story told by the ground. Although I have never
ridden a mountain bike, I am very familiar with their impacts. For the last
seven years I have regularly run three to six miles several times a week on a
network of trails in the Sandia Mountain foothills two blocks from my home. …
These trails receive use from walkers, runners, and mountain bikers; they are
closed to motorized vehicles.
Because I'm clumsy, I keep my eyes on the trail in front of me. I run or
walk in all seasons, in all kinds of weather. I have watched the growing erosion
on these trails from mountain bike use. The basic difference between feet and
tires is that tire tracks are continuous and foot tracks are discontinuous.
Water finds that narrow, continuous tire tracks are a rill in which to flow.
Also, because many mountain bikers are after thrills and speed, their tires cut
into the ground. Slamming on the brakes after zooming downhill, sliding around
sharp corners, and digging in to go uphill: I see the results of this behavior
weekly. …
I regularly see mountain bikers cutting off cross-country, even on steep
slopes, for more of a challenge. They seem blind and deaf to the damage they
cause. Admittedly, backpackers and horsepackers can cause damage to wilderness
trails. But this is a poor argument to suggest that we add another source of
damage to those trails." Dave Foreman
"Studies show that bike impacts are similar to those of other non-motorized
trail users." Jim Hasenauer (professor of rhetoric and member of the board of
directors of the International Mountain Bicyclists Association)
Introduction:
I first became interested in the problem of mountain biking in 1994. I
had been studying the impacts of the presence of humans on wildlife, and had
come to the conclusion that there needs to be habitat that is entirely
off-limits to humans, in order that wildlife that is sensitive to the presence
of humans can survive (see Vandeman, 2000). But what is the best way to minimize
the presence of people? Restricting human access is repugnant, and difficult and
expensive to accomplish. It occurred to me that the best way to reduce the
presence and impacts of humans is to restrict the technologies that they are
allowed to utilize in nature: e.g. prohibit bicycles and other vehicles (and
perhaps even domesticated animals, when used as vehicles).
Having been a transportation activist for eight years (working on
stopping highway construction), and having a favorable view of my fellow
bicyclists as environmentalists, I turned to them to help me campaign to keep
bicycles out of natural areas. Was I ever surprised! I discovered that many
bicyclists (e.g. many mountain bikers) aren't environmentalists at all, but are
simply people who like to bicycle -- in the case of mountain bikers, many of
them just use nature, as a kind of playground or outdoor gymnasium! (Of course,
there are also hikers, equestrians, and other recreationists who fall into this
category.) To my suggestion to keep bikes off of trails in order to protect
wildlife, they reacted with hostility! (There is a degree of balkanization among
activists, where some transportation activists ignore the needs of wildlife, and
some wildlife activists eschew bikes and public transit.)
In 1994 I attended a public hearing held by the East Bay Municipal
Utility (water) District to decide whether to allow bikes on their watershed
lands. Mountain bikers were there asking for bike access, and the Sierra Club
was there to retain the right to hike, while keeping out the bicycles. I said
that I had no interest in using the watershed, but that I wanted to ensure that
the wildlife are protected -- hence, I asked that bikes not be allowed.
Afterward, the EBMUD Board of Directors took a field trip to Marin County, the
birthplace of mountain biking, to see the effects of mountain biking there.
While they were hiking along a narrow trail, a mountain biker came racing by,
swearing at them for not getting out of his way fast enough. That helped them
decide to ban bikes. Today bikes are still restricted to paved roads, and EBMUD
is still one of the public agencies most protective of wildlife.
It is obvious that mountain biking is harmful to some wildlife and
people. No one, even mountain bikers, tries to deny 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, facilitate increased levels of human access into
wildlife habitat, and drive other trail users (many of whom are seeking the
tranquility and primitiveness of natural surroundings) out of the parks. Because
land managers were starting to ban bikes from trails, the 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. But there are two problems
with this approach: (1) it's not true, and (2) it's irrelevant.
I will examine (1) in a moment. But first, let's look at relevance:
whether or not hiking (or All Terrain Vehicles or urban sprawl or anything else)
is harmful really has no bearing on whether mountain biking is harmful: they are
independent questions. Such a comparison would only be relevant if one were
committed to allowing only one activity or the other, and wanted to know which
is more harmful. In reality, hiking is always allowed, and the question is
whether to add mountain biking as a permitted activity. In that case, the only
relevant question is: Is mountain biking harmful? Of course, it is. However,
since many people seem interested in the outcome of the comparison, I will
examine the research and try to answer it.
The mountain bikers' other line of research aims to prove that mountain
bikers are just like hikers, implying that they should have the same privileges
as hikers. (Of course, they already have the same privileges! The exact same
rules apply to both groups: both are allowed to hike everywhere, and neither is
allowed to bring a bike where they aren't allowed.) Using surveys, they have
tried to show that mountain bikers are really environmentalists, lovers of
nature, and deep ecologists. Of course, surveys are notoriously unreliable:
statements of belief don't easily translate into behavior. I'm going to ignore
this research, since I am (and the wildlife are) more interested in actual
impacts, not intentions.
The International Mountain Biking Association (IMBA) has done me the
favor of collecting all the research they could find that seemed favorable to
mountain biking. Gary Sprung (2004) summarized it in his carefully worded essay,
"Natural Resource Impacts of Mountain Biking". Gary says "the empirical studies
thus far do not support the notion that bikes cause more natural resource
impact". I will show that this is not true; in fact, those studies, if their
data are interpreted properly, show the exact opposite: that mountain biking has
much greater impact than hiking! Gary says that we should make "make rational,
non-arbitrary, less political decisions regarding which groups are allowed on
particular routes". This is disingenuous. Mountain bikers (but not bikes) are
already allowed on every trail.
Impacts on Soil (Erosion):
Gary says "No scientific studies show that mountain bikers cause more
wear to trails than other users". He cites Wilson and Seney (1994) and claims
that "hooves and feet erode more than wheels. … Wilson and Seney found no
statistically significant difference between measured bicycling and hiking
effects". He quotes the study: "Horses and hikers (hooves and feet) made more
sediment available than wheels (motorcycles and off-road bicycles) on prewetted
trails" (p.74).
This study is frequently cited by mountain bikers as proof that mountain
biking doesn't cause more impact than hiking. But it has a number of defects
that call its conclusions into question. The authors used a "rainfall simulator"
to measure "sediment made available" by the various treatments. They
"[collected] surface runoff and sediment yield produced by the simulated
rainstorms at the downslope end of each plot", which they claim "correlates with
erosion" (they don't say what the correlation coefficient is). This doesn't seem
like a good measure of erosion. For example, if a large rock were dislodged, the
very weak "simulated rainfall" wouldn't be capable of transporting it into the
collecting tray; only very fine particles would be collected. In fact, they
admit that the simulator's "small size … meant that the kinetic energy of the
simulated rainfall events was roughly one-third that of natural rainstorms".
Another reason to suspect that the measurements aren't valid is that "none of
the relationships between water runoff and soil texture, slope, antecedent soil
moisture, trail roughness, and soil resistance was statistically significant".
The authors also ignored the relative distances that various trail users
typically travel (for example, bikers generally travel several times as far as
hikers, multiplying their impacts accordingly) and the additional impacts due to
the mountain bike bringing new people to the trails that otherwise would not
have been there (the same omission is true of all other studies, except Wisdom
et al (2004)). They do say "Trail use in the last ten years has seen a dramatic
increase in off-road bicycles" (p.86), but they don't incorporate this fact into
their comparison. In addition, there is no recognition of different styles of
riding and their effect on erosion. We don't know if the mountain bikers rode in
representative fashion, or, more likely, rode more gently, with less skidding,
acceleration, braking, and turning. There was also no recognition that soil
displaced sideways (rather than downhill) also constitutes erosion damage. It
seems likely that they underestimated the true impacts of mountain biking. I
don't think that these results are reliable. (Note that the study was partially
funded by IMBA.)
Gary next cited Chiu ([email hidden]) and Kriwoken
([email hidden]), claiming that there was "no significant difference
between hiking and biking trail wear". I wasn't able to acquire this study, but
it is apparent from Gary's description of it that he (and perhaps the authors)
misstated the conclusions. If we assume, as they claim, that bikers and hikers
have the same impact per mile (which is what they measured), then it follows
that mountain bikers have several times the impact of hikers, since they
generally travel several times as far. (I haven't found any published
statistics, but I have informally collected 72 mountain bikers' ride
announcements, which advertise rides of a minimum of 8 miles, an average of 27
miles, and a maximum of 112 miles.)
Impacts on Plants:
Gary says "No scientific studies indicate that bicycling causes more
degradation of plants than hiking. Trails are places primarily devoid of
vegetation, so for trail use in the center of existing paths, impacts to
vegetation are not a concern." However this is a concern for plants that try to
