Trail sustainability = hydrologic invisibility
Before I can really get into the sustainability disussion, I first need to see all user groups on equal footing.
Ah, but here's the beauty of looking at it first from the point of sustainability--I don't care what kind of user is on a particular trail if that trail is either built for that type of mode, or the style of use conserves the trail...in this way it doesn't matter if they're on foot, horse, ATV, MTB, whatever...what does matter is whether their use contributes to the continued dynamic deterioration of the landscape...I've hung out with ATVers who have a much more dedicated attitude to trail maintenance/improvement/stabilization, and in fact find them easier to rally than the "let's not touch nature because nature knows best--but it's OK to pound in a 6 foot gully up that was once a fall-line trail on [name any peak on the Chugach front range]" greenie-wannabe. Personal biases of various folks become pretty clear (and neutralized) when the focus is on sustainability...people can jump out of their 'name, blame and shame an enemy' and focus on a common challenge...or just retreat to their corner and sue, sue, sue like is done in California.
So back to what sustainability is? To borrow from IMBA, for a trail I think it comes down to "hydrologic invisibility" on the landscape...when precipitation and/or moisture events happen, it moves right over the trail without picking up and/or moving any soil from the trail corridor (corridor includes any adjacent drainage structures like uphill ditches, etc. along with trail tread) Adjacent natural vegetation recovers and reaches an equilibrium or dynamic steady-state, just as the trail does...the alternative is that when a trail is hydrologically visible, it captures water movement, deprives the downgradient/downstream biologic receptors, and totally replaces the natural system with one that most likely is developing more volume and speed, gathering materials, and creating erosion, on an exponential basis...
Some good examples of sustainable trails include the Inca Trail in Peru, Roman roads all over Europe, especially the ones that have become models for the Welsh MTB system and re-born techniques like stone-pitching in Wales, lots of trail work done by the CCC in the 30's, and some stuff done by miners and the AK Road Commission almost a hundred years ago when all they had were their hands and horses...there are still lots of good trails out there that just need to be brushed out!
Finally, onto the walking on the virgin tundra, or cryptobiotic crust, which exists all over AK tundra, just like in the SW Lower 48...routes can be chosen that minimize impacts (ie., hiking on sidehills, or on scree/rock, rather than veg, avoiding walking in others trail, avoid fall line routes) but if ya' get up in the air you usually see that the sheep and caribou, or maybe even moose have been pounding the hell out of the tundra...a certain amount of damage is inevitable, so it pays to go with a bit of consciousness and perhaps gratitude for the cool experience the earth gives us, and maybe giving something back (like doing some trail work!! ) After all, the only way we can't have an impact on the earth is to be dead! And the most basic definition of whether something is alive is whether it eats and shits!
Ride on!
