Terra Logic performed Line-Point Intercept surveys of five Colorado Department of Transportation right-of-ways to evaluate revegetation conditions. The surveys found on average 86% canopy cover, 6% bare ground, and 17% basal cover across the sites. Hwy 285 had the highest scores with 98% cover and 24% basal cover after 12 years. Overall health averaged 3.2 out of 5. Recommendations include using only native species in seed mixes matched to the local ecology, and maintaining best practices like retaining topsoil.

1. Integrated Evaluation of Revegetation Conditions for Five Colorado
Right-of-Ways Using Line-Point Intercept Surveys
Oct 12, 2014
Denise C Wilson
In July and August of 2014, Terra Logic, LLC performed a Line-Point Intercept survey
study of roadside revegetation on five past Colorado highway construction sites.
TerraLogic was contracted by the Colorado Department of Transportation (CDOT) to
evaluate revegetation conditions on selected right-of-way locations in Colorado. This is
the summary of the results obtained from the five forensic analyses, with an integrated
evaluation assessment and general recommendations for how to improve Best
Management Practices for roadside revegetation.
When comparing five different survey locations, it is important to recognize that each
represents a different ecosystem. Hwy 285 north of Conifer is a Lower Montane
ecosystem comprising mixed grasses, shrubs and forbs, with soils that are moderately
deep to shallow, formed in loamy material with high percentages of cobbles and stones.
TREX, at the University interchange in Denver, is near to remnant Tallgrass Prairie plots
with soils of humus, sand and small stones created by floods of the South Platte River.
East Berthoud Pass is a sub-alpine mixed-conifer forest with shallow, rocky soils, and a
short growing season. Powers Blvd north of Colorado Springs has a similar ecosystem to
TREX, but within the floodplain of Monument Creek, and it is near High Plains
Shortgrass Prairie. Hwy 50 east of Grand Junction is a cold, arid, semi-desert plateau
with shallow and impermeable alkaline clay rich in calcium sulfate, selenium and
sodium, which create conditions outside the tolerance of most plants. Despite these
differences, the survey scores are similar enough in range to reveal some commonalities
of revegetation strengths and limitations. Table 1 lists the years that the vegetation has
grown and summarizes the average scores for each site for each category.
TABLE 1 - Summary Scores for All Five CDOT Line-Point Surveys
Site
Yrs
Ref. Canopy
Cover
Bare
Ground
Basal
Cover Grazing
Overall
Health
Native
Abundance
Ecological
ContinuityGrowth Plot
Hwy 285 12 4 98% 0% 24% 1.2 3.4 3.4 3.2
TREX 13 4 83% 0% 8% 2.3 2.5 3.2 3.7
Berthoud 10 3-1,
3-2 82% 10% 17% 2.8 3.8 3.8 4.3
Powers 1 3 86% 4% 22% 1.6 4.2 4 4
Hwy 50 15 6 82% 16% 14% 2.2 2 2 1.8
*Mean 10.2 86% 6% 17% 2.0 3.2 3.3 3.4
*excludes Ref. (reference) plot
1-low 5-high

2. Mean Scores Evaluations for Five Locations
Canopy Cover, Bare Ground and Basal Cover Scores are Related
At each vertical data point, the survey captured a top canopy layer of plant material
observed; and also the lower layer of any plant material on the surface of the soil. A
significant amount, 86%, had foliar canopy cover, and further, only 6% was bare ground
on the soil surface. We can infer from the results that the ground was mostly covered by
revegetation at the CDOT locations surveyed. However, only 17% had basal cover; the
ground had leaf and litter coverage, but the surface of the soil had 17% growing plants
occupying space. A higher basal cover would mean more plants with wide basal leaves
and/or tufted plants with spreading rhizomatous roots, instead of stems arising from
taproots. This would provide more coverage and less competition for weeds, a major
vegetation roadside problem.
The highest score was on Hwy 285, which was 98% revegetated with 0% bare ground,
and the highest plant basal cover, (24%) of any of the survey sites. The weeds were
controlled at this site, and it proved to be excellently revegetated twelve years after
construction. The lowest scores were on Hwy 50, where the canopy cover was 82%, with
16% bare ground, and only 14% basal cover; however, many of the plants recorded were
weeds and introduced, non-native species. This exemplifies inadequate revegetation
because of the non-native nature of the plants. Berthoud Pass had similar scores for
cover, bare ground and basal coverage, but in contrast, most of the plants were natives;
with the caveat that mixed conifer forests can have a low percentage of foliar ground
cover due to high competition for sunlight and the accumulation of acidic conifer needles.
Thus, Berthoud showed a better revegetation result.
Qualitative Characteristics
The data sheets for each survey also included an observational judgment of four
qualitative characteristics, with a score of 1 – 5, low to high, for Grazing & Herbivory,
Overall Health, Native Plant Abundance, and Ecological Continuity.
Grazing & Herbivory
The mean for Grazing & Herbivory was 2, which indicates a below average defoliating or
clipping damage to plants. All of the plots showed below average grazing and herbivory.
TREX showed considerable defoliation from insects; this is an urban environment with
more concrete and warmth for insect reproduction. Damage was observed at Berthoud
Pass due to grazing deer, elk and moose, along with small mammals, but there was little
sign of insect grazing there.
Overall Health and Native Abundance
Overall Health mean was 3.2; about average, but the range of scores is wide, with Powers
Blvd scoring the highest, at 4.2, where plants were tall and healthy with few noxious
weeds, vs. Hwy 50 with a score of 2, where the healthiest plants appeared to be weeds
and kochia, an introduced species. Native Abundance followed closely with a mean
score of 3.3; similarly, Powers Blvd scored 4, and Hwy 50 a 2. These two categories tie

3. together; the observation of healthy native plants unencumbered by weeds leads to
similar scores for each category. Hwy 285, Powers and Berthoud were all high in native
plant diversity, with Berthoud Pass exhibiting the highest ratio of native plants.
Monocultures of introduced grass species were observed, such as smooth brome,
Kentucky bluegrass, timothy, and orchard grass, and these lowered the scores at several
transects. These non-native species were historically used for restoration because of the
high forage content for domesticated grazing animals, but are inappropriate for native
restoration.
Ecological Continuity
Ecological Continuity takes into consideration the health of the surrounding landscape;
the urban weedy survey sites were adjacent to urban weedy native sites. The mean is
actually a little higher, at 3.4, than Overall Health and Native Abundance, with better
than average continuity. Alas, weeds are abundant in urban environments, so the weedy
roadside begins to blend with the surrounding weedy habitat.
Powers Blvd Transect Plot One Year After Revegetation Efforts
Although Powers Blvd. survey data was collected only one year after revegetation, the
results are comparable to 10 -15 years of growth, at each of the four other sites surveyed.
This could be attributed to several possible factors:
• the level of detail, methodologies and management have improved over the past
15 years so that CDOT is better at revegetation;
• In 2014 the area received good rainfall;
• The first year's results are a good indicator of future right-of-way plant
regeneration;
• Hwy 50 is semi-desert and the saltbush take many years to develop, so it is not a
comparable site;
• Likewise, the elevation of Berthoud Pass’ plots was above 10,000 feet where,
because of short growing seasons, plants can take many years to establish, and so
was not comparable to Powers Blvd;
• Powers Blvd. construction reclamation was superior in some other unidentified
way to achieve as much plant growth in one year as the others in 10 to 15 years;
• Roadside revegetation cannot be expected to consistently exceed these averages
because of the inherent difficulties of vegetation reclamation;
• Roadside maintenance over time introduces pollutants, and exotic plants get
introduced which effect the overall health of roadside vegetation, causing
degradation over time;
• The survey sample is too small;
• Other unidentified factors.
Common Treatments and Amendments are Working Well
The results of these diverse transect plots suggest that CDOT is doing a good job with
right-of-way revegetation and should maintain and refine their Best Management
Practices for reclamations. In general, soil amendments which improve the quality of the
soil produce better vegetation. Specifically, the site’s soil needs to be analyzed and

4. matched, as in the case of Hwy 50, where the native soils have unusual characteristics,
and creating better soil just makes fertile ground for weeds and non-native plants.
Mulching and mulch tackifier are necessary to keep seeds in place and take advantage of
precipitation on sites that are not irrigated. Adding compost to the topsoil mix elevates
the organic matter content, contributes nutrients and improves moisture retention.
Looking at Revegetation Success Relative to the Surrounding Natural Landscape
If the goal is to produce a roadside of native, weed free vegetation, then the plant species
of the immediate environments should be examined. Each of the five locations had a
native reference, or background plot. It was often difficult to locate a reference plot
contiguous to the right-of-way being plotted since most of the sites were populated and
well developed and had altered plant species as a result of past ranching or farming.
These scores below in Table 2 list the four characteristics relative to each location’s
native plot, plus a group mean for each characteristic. A general viewing of these figures
shows much more variation between the sites than the summary scores in Table 1. This
is because each site is being compared to an ideal local native plot.
Table 2 – Summary Scores for Relative Health Evaluations and Percent of Cover
Site Grazing Overall
Health
Native
Abundance
Ecological
Continuity
Percent
Seedmix
Observed
Hwy 285 60% 85% 68% 64% 35%
TREX 117% 83% 63% 73% 31%
Berthoud
Pass 81% 85% 75% 87% 47%
Powers
Blvd 80% 105% 80% 80% 28%
Hwy 50 55% 40% 40% 36% 16%
*Mean 79% 80% 65% 68% 31%
Again, it is informative to examine the high and low scores, and account for success and
failure.
Grazing
The low score is on Hwy 50 with a score of 55%, and TREX with a score of 117%. The
survey team observed a high level of defoliation and insect nests on the plants at TREX.
A low score in this characteristic indicates a positive condition of low grazing or
herbivory compared to the native adjacent plot. Small mammals were observed by the
team at both sites.
Overall Health
The low is Hwy 50, with 40%, and the high is Powers Blvd with 105%. The challenges
of clay soils, salinity and alkalinity along Hwy 50 have already been noted. Powers Blvd
had received soils superior to the adjacent native plot, which may have accounted for

5. better plant health in the reclaimed area than the contiguous native plot. The other three
locations show good overall plant health.
Native Abundance
The low score is Hwy 50, with 40%; the high is Powers Blvd scoring 80%, followed by
Berthoud Pass with 75%. Hwy 50 plant coverage was comprised mainly of weeds,
whereas Powers Blvd and Berthoud Pass plant coverage was a diverse mix of native
species. Seedmix establishment and native plant colonization were very good at both of
these sites because of improved soil amendments during reclamation.
Ecological Continuity
The low score is 36% for Hwy 50, and the high is 87% for Berthoud Pass. Hwy 50’s
roadside revegetation of weedy species appeared very different from the indigenous mat
saltbush community. Berthoud Pass roadside revegetation appeared very similar to the
native plot, comprising many diverse plant species.
Percent Seedmix Observed
This category, not originally in the scope of work, was added to quantify the level of
success of the seedmix plant species’growth. Again, Hwy 50 is the low score, with 16%
of the seedmix species observed, and Berthoud Pass is the highest score, with 47%
observed. Hwy 50 seedmix could have included a species list better matched to the
natural environment, particularly the grasses, although the chosen shrub species were
correct. Berthoud Pass seedmix was composed of several species native to the area, and
this helped plant establishment, health, and overall revegetation.
Recommendations
• A survey of existing vegetation and percent cover should be conducted prior to
commencing construction. This data should determine the components of the
seedmix. An observational walk-through and compilation of plant species at an
adjacent native site will result in a list long enough to be able to cull 8-14 plant
species which grow naturally on site from which the seedmix of available species
and the quantities needed can be derived.
• The reclamation seedmix should contain native plant species only, no introduced
species.
• Grass species might be considered exclusively in the first year, followed by an
application of herbicides to eliminate weeds, followed by a seeding of native
grasses and forbs in the second year.
• Seedmix should contain at least one sterile species (such as oats used at Powers or
Regreen used at Hwy 50) to quickly establish ground cover; or a one-season crop
species to provide coverage by the end of the first season. This controls early
weeds and exotic species the following spring. Ground coverage is the goal.
• Additionally, the seedmix needs a plant species, such as slender wheatgrass
(Elymus trachycaulus) for montane, sub-alpine and alpine habitats, which is early
successional; these grasses establish quickly and typically flourish for 2-3 years
while native plant seeds colonize from the surrounding area. The NRCS

6. document, Early Successional Habitat, can be used as a resource reference for
development of Best Management Practices.
• Best Management Practices, such as retaining and redistributing topsoil, must be
maintained. This topsoil should be disturbed as little as possible and scrapped
mechanically to preserve the soil horizon.
• Detritus such as chipped trees and brush, grounded sticks and logs, leaves and
dead plant matter can be used in the top soil layer as these encourage the
development of mycorrhizal fungi. Mycorrhizal inoculation should be tested for
viability and cost considerations.
• Seedmix needs to be diverse enough to encompass plant species with different
basal growth forms and different root systems. Select for basal growth rosettes,
as well as robust stems; for roots fibrous and rhizomatous vs. a long taproot. This
diversity provides vegetation cover in different conditions. This provides some
insurance against extreme weather conditions such as drought or flooding due to
changing climates.
.
References
Early Successional Habitat, NRCS; 2007;
http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs143_010001.pdf

7. document, Early Successional Habitat, can be used as a resource reference for
development of Best Management Practices.
• Best Management Practices, such as retaining and redistributing topsoil, must be
maintained. This topsoil should be disturbed as little as possible and scrapped
mechanically to preserve the soil horizon.
• Detritus such as chipped trees and brush, grounded sticks and logs, leaves and
dead plant matter can be used in the top soil layer as these encourage the
development of mycorrhizal fungi. Mycorrhizal inoculation should be tested for
viability and cost considerations.
• Seedmix needs to be diverse enough to encompass plant species with different
basal growth forms and different root systems. Select for basal growth rosettes,
as well as robust stems; for roots fibrous and rhizomatous vs. a long taproot. This
diversity provides vegetation cover in different conditions. This provides some
insurance against extreme weather conditions such as drought or flooding due to
changing climates.
.
References
Early Successional Habitat, NRCS; 2007;
http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs143_010001.pdf