This project investigates tree health along gravel roads in Larimer and Grand Counties, Colorado' In

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Impacts of Magnesium Chloride - Based Dust
Suppression Products on the Health of Roadside
Vegetation Betsy A. Goodrich1,2, Dr. William R.
Jacobi1,2, and Ronda D. Koski1 1Department of
Bioagricultural Sciences and Pest Management,
CSU, Ft. Collins, Colorado 80523-1177 2Graduate
Degree Program in Ecology, Colorado State
University, Fort Collins, Colorado 80523
Background
Results Soil chemistry
Plot Design and Data Collection
This project investigates tree health along
gravel roads in Larimer and Grand Counties,
Colorado. In summer 2004 forty-six vegetation
health plots were established in upslope and
downslope pairs on nine roads with various
amounts of salts. Trees, woody shrubs, and
herbaceous ground covers were assessed for
abiotic and biotic damages. Soil and foliage
samples were collected from 35 plots at four
distances from the road (0, 10, 20, and 40
feet) and analyzed for chemical content. Plot
design and layout is to the right.
Besides its use for snow and ice control,
magnesium chloride (MgCl2) is applied to gravel
roads during summer months for dust suppression
and road stabilization. Dust suppressants are
used to control maintenance costs, erosion, and
fugitive dust. The use of dust suppressants is
increasing in order to control particulates in
the interest of air quality.

Figure 4. Mean chloride values (log10 /- 1 SE)
at 4 distances from the road.
Figure 5. Mean magnesium values (log10 /- 1SE)
at 4 distances from the road.

• Chloride values were significantly higher
  directly on the road shoulder (0 ft).
• Downslope values were significantly higher than
  upslope values at 0 and 10 ft ().
• Upslope and downslope differences between 20 and
  40 ft were not significant.
• There were no significant differences between
  slopes for mean magnesium values.

Results Tree Health

Introduction
Research quantifying the impacts of MgCl2 on
vegetation is limited. Based on research of
sodium chloride (NaCl) symptoms of salt damage
can include tip or marginal burn, necrosis, or
early fall defoliation. Salts in the soil can
depress the osmotic potential and restrict water
uptake by plant roots. Ion accumulation in woody
plants can cause osmotic stress in plant tissues.

Figure 6. Mean ECe values (/- 1 SE) at four
distances from the road.
Figure 7. All ECe values at four distances from
the road.

• ECe is a measure of soil salinity (measured in
  mmhos/cm).
• ECe significantly decreases as distance from the
  road increases.
• ECe upslope and downslope differences at 0 and
  10 ft were significant ().
• Plant species tolerance to salinity varies.
  Some plants species will be
• affected if ECe gt 2 - 4 mmhos/cm.
• Continued monitoring and analysis over the next
  two years will determine if salinity
• levels correlate with plant health status.

Figure 2. Mean engelmann spruce (Picea
engelmannii) health (/- 1 SE) along gravel roads.
Figure 1. Mean lodgepole pine (Pinus contorta)
health (/- 1 SE) along gravel roads.
Figure 3. Mean aspen (Populus tremuloides)
health (/- 1 SE) along gravel roads.

• Lodgepole pines and Engelmann spruce were
  healthier on average
• as distance from the road increased.
• Aspen trees did not follow the same pattern of
  health.
• In all three species, upslope trees were in
  significantly better health
• than downslope trees at 0-10 feet.
• Trees furthest from the road were not always
  considered healthy.
• Many biotic damages were associated with tree
  health decline in our
• plots, including effects difficult to diagnose,
  such as drought.

Three different habitat types
of forest health plots in Grand and Larimer
Counties.
Objectives

• Objectives of this study are to determine if
• MgCl2 is moving from roads to roadside
  environments.
• MgCl2 causes adverse effects on vegetation.
• (preliminary results from above objectives
  reported in this research poster)
• MgCl2 moves from roads through drainage systems.
• site factors influence the movement of MgCl2.
• there is need to implement better management
• practices in application procedures.