Mountain bike activity in natural areas - Murdoch Research ...

A case study from John Forrest National Park, Western Australia
2007). They are physically measurable parameters that provide a method of evaluating trends in conditions and
are an efficient way of collecting relevant data (Marion 2007). Indicators must be easy to measure, locally
relevant, represent the effect that we are trying to understand and reflect the impacts of recreational use (McCool
1996, Bicycle SA 2001).
A criticism of previous studies assessing mountain biking impacts, summarised in Sprung (2004), is that
mountain bike specific impacts have not been considered in depth, like ruts and grooves caused by skidding and
breaking and increased distance of travel (Vandeman 2000). A comprehensive study should measure these
impacts and must include sections of uphill, downhill and flat stretches combined with straights and curves
(Beneficial Designs 1999, Goeft & Alder 2001). A suggested approach to investigating mountain bike specific
impacts has been developed by Newsome and Davies (in press) with specified impacts and indicators
summarised in Table 2.
Table A2: Summary of potential indicators from multiple user trail usage and use of trails by mountain
bikes
Impact
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General Indicator Mountain Bike Specific Indicator
Soil erosion Trail cross sectional area (m 2 )
Maximum incision (mm)
Depth x length x width
Soil compaction kg/ cm 2
Penetrometer or bulk density
Tyre incision depth (mm) and lineal
extent (m)
Tyre marks in dry compacted areas
(number and length)
Trail muddiness Muddiness (% of tread width) Tyre marks in muddy areas (number and
length)
Trail widening Max width of trail as identified by
tread marks (m)
Tread width Tread width (m)
Trail surface Loose/displaced soil, compacted
Subsoil exposure
Informal Trails No of trails, condition, length, width,
area, proximity to sensitive areas,
erosion measurements as per formal
trails.
Multiple trails Parallel trails or diversions around
obstacle (number of)
Maximum width of trail as identified by
tyre marks (m)
Loose/displaced soil due to sudden
application of brakes and skidding
As general indicator but determine user
group from trail markings/other
indicative evidence
Parallel trails or diversions around
obstacle made by tyre imprints (number
of)
Trail modifications Technical Trail Features (number and
description)
Maintenance features Water bars, crossings, grade reversals
(number and condition rating)
Directional signage and
interpretation
Vegetation (trail edge
and on trail)
Designated mountain bike trail with
relevant interpretive signage
Functional/non-functional Functional/non-functional on multiple
use/mountain bike designated trails
Identification and number of weeds or
bare ground (% of quadrant)
Derived from Leung & Marion 1998, Goeft & Alder 2001, Meyer 2002, Newsome et al. 2002, Marion per comm. 2007, White et al. 2006,
Castley et al. 2007.