United States

Department

of Agriculture

Forest Service

Rocky Mountain

Research Station

General Technical Report 

RMRS-GTR-215

September 2008

Soil Compaction Monitoring 

of the Pool Timber Sale, 

Rio Grande National Forest, 

Colorado, 16 Years After Logging

John J. Rawinski and Deborah S. Page-Dumroese
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Rocky Mountain Research Station

240 W. Prospect Road

Fort Collins, Colorado 80526

Rawinski, John J.; Page-Dumroese, Deborah S. 2008. Soil compaction 

monitoring of the Pool Timber Sale, Rio Grande National Forest, Colorado, 

16 years after logging. Gen. Tech. Rep. RMRS-GTR-215. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station. 

12 p.

Abstract

We conducted a soil monitoring project in 1992 after a shelterwood harvest. One 

year after harvesting, we determined that 21.32 percent of the area in Unit 5 of the 

Pool Timber Sale was considered to have detrimental soil compaction. In 2007, 

we conducted another monitoring project on the same stand by the same person 

to determine the degree of soil compaction recovery on skid trails. Results from the 

2007 monitoring showed that detrimental soil compaction still existed in the stand 

and that there was no significant difference between the 1992 and the 2007 skid 

trail bulk densities. Monitoring the occurrence of platy structure on these sites was 

not an accurate predictor of detrimental soil compaction.

Keywords: compaction, soil monitoring, skid trails, soil recovery, harvesting

Authors

John J. Rawinski is Soil Scientist on the Rio Grande National Forest, Monte 

Vista, Colorado. John received his BS in forestry in 1975 from the University of 

Massachusetts, Amherst. He received an MS in soil science from the University of 

Wisconsin-Stevens Point in 1978.

Deborah S. Page-Dumroese is a Research Soil Scientist with the Rocky Mountain 

Research Station, Moscow, Idaho. She completed a BS degree in natural resource 

management at Grand Valley State University, an MS degree in forest soils from 

Michigan Technological University, and a PhD in forest soils at the University of 

Idaho.

Photos within this paper were taken by John Rawinski.
Contents

Introduction....................................................................................................... 1

Methods and Materials..................................................................................... 1

Site Description ........................................................................................... 1

Harvest Methods ......................................................................................... 1

Soil Monitoring Methods.............................................................................. 2

Results and Discussion................................................................................... 3

1992 Pool Monitoring Project Summary...................................................... 3

2007 Monitoring Project Summary.............................................................. 3

Variability in Unit 5....................................................................................... 4

Analysis of Platy Structure .......................................................................... 5

Growth-Limiting Bulk Density Analysis........................................................ 5

Miscellaneous Areas ................................................................................... 6

Summary..................................................................................................... 6

Management Implications ........................................................................... 6

Acknowledgments............................................................................................ 7

Literature Cited................................................................................................. 7

APPENDIX A. Field Data and Statistical Analysis ........................................ 8

APPENDIX B. Pool Timber Sale Monitoring Site Rio Grande 

 National Forest, Colorado ........................................................................ 9

USDA Forest Service RMRS-GTR-215. 2008. 1

Introduction

In southwest Colorado, recent insect outbreaks have 

resulted in some forested stands being re-entered after 

a 10 to 20 year absence of logging activity. Assessing 

the existing soil impacts within a stand is necessary to 

meet the intent of the National Environmental Policy 

Act to describe the existing conditions as well as to estimate cumulative effects. In addition, because of the 

National Forest Management Act of 1976 and related 

legislation, management of public lands must maintain 

the productive potential of National Forest lands. With 

the enactment of the Healthy Forest Restoration Act in 

2003, forest management decisions increasingly rely on 

repeated entries to conduct partial cuts for the removal of 

small-diameter trees from forest stands. However, these 

multiple entries by mechanical equipment to reduce potential wildfire risk and severity may impact ecosystem 

processes and site sustainability. As described in Curran 

and others (2005), multiple stand entries can increase 

soil impacts so that cumulative effects at the stand and 

watershed scale become significant.

In USFS Region 2, managers often question the 

longevity of soil compaction and the rate of soil recovery following harvest activities. Numerous studies 

have shown that once compacted, forest soils are often slow to recover and may require decades to return 

to pre-disturbance levels (Froehlich and others 1985; 

Sands and others 1979; Tiarks and Haywood 1996). 

However, recovery rates are dependent on many factors, but chief among them is repeated harvest cycles, 

soil moisture conditions at the time of harvest, soil 

texture, and rock-fragment content (Liechty and others 2002). The extent and depth of impact, initial bulk 

density, and the recovery rate are all factors that determine the consequences of timber harvesting on site 

sustainability.

Soil standards and guidelines in USFS Region 2 require that no more than 15 percent of an activity area 

have “detrimental” soil impacts (areal extent) and the 

Supplement defines detrimental soil compaction as an 

increase in soil bulk density of >15 percent over natural conditions (USDA Forest Service FSH 2509.18 

1992; USDA Forest Service 1996). Exceeding the 

standards prior to another harvest cycle could indicate 

the need for some form of site amelioration. However, 

data is scarce on the long-term recovery of compaction 

on high-elevation sites in Colorado. Consequently, 

the objective of this study was to re-monitor a site 

that had been previously logged and monitored to 

determine if soil compaction levels had recovered to predisturbance levels.

Methods and Materials

Site Description

The harvest unit is located in the NW 1⁄4 of the 

NE 1⁄4 of section 23, T 41 N, R 2 E. Elevation is 

3352 m (11,000 ft) and the mean annual precipitation 

is 63.5 cm (25 in). The Ecological Unit for this site 

is MU 165 (subalpine fir (Abies lasiocarpa [Hook.] 

Nutt) and Engelmann spruce (Picea engelmannii Parry 

ex Engelm.)) on Seitz soils, moist phase. Sietz soils 

are very deep, well-drained clayey-skeletal, smectitic Ustic Glossocryalfs (Soil Survey Staff 1999). 

In the surface 25 cm (10 in), gravelly loam was the 

dominant texture and fine gravel was the predominant 

coarse-fragment size class, comprising an average of 

20 percent by volume.

Harvest Methods

The most recent timber harvest occurred in June 

1991 (Unit 5 Pool Timber Sale) using a Timbco wholetree harvester, which is a tracked implement. Once the 

harvester cut the timber, it was stacked near a series of 

skid trails for removal by a grapple (wheeled) skidder. 

Soil Compaction Monitoring of the Pool Timber Sale, 

Rio Grande National Forest, Colorado 

16 Years after Logging

John J. Rawinski and Deborah S. Page-Dumroese
2 USDA Forest Service RMRS-GTR-215. 2008.

At the landing area, trees were delimbed and bucked to 

length. Additionally, records indicated that there was a 

timber harvest on this site prior to 1962, but details on 

the type of equipment used and the amount of timber 

extracted were unavailable.

Soil Monitoring Methods

Soil monitoring was done in June 1992 using the 

soil monitoring protocol established by Howes and 

others (1983). Soil bulk density cores (core volume 

was 90.38 cm3

) were collected to estimate soil compaction levels within the stand. The protocol outlined 

in Howes and others (1983) defines three visual classes: (1) the skid trail visual class occurs only on defined 

skid trails, (2) the miscellaneous visual class can be 

found in areas where equipment has disturbed the 

surface soil layer, but not in a defined skid trail, and 

(3) the undisturbed visual class occurs when no trafficking can be noted on the soil surface. While all three of 

these visual classes were used for sample collection in 

1992, only the skid trail visual class was used in 2007. 

A complete re-sampling of this unit using all three visual classes in the protocol was not possible due to 

funding constraints. No GPS coordinates were taken 

15 years ago during the initial sampling, and therefore 

exact transects points could not be re-located. Instead, 

we re-established the stand boundary using air photos, established GPS coordination, and identified the 

main skid trails within the unit. We chose to stratify 

our sampling and confine it to the skid trails since they 

were still recognizable after 16 years.

A random number generator was used to establish sampling distances on each of the four main skid 

trails. Teams of two to four individuals collected the 

soil core samples on June 21, 2007. This date approximated the date of the 1992 sampling (June 17, 1992). 

Each soil sampling point was alternately directed toward left wheel rut, center, and right wheel rut. We 

used the same core sampler tools (90.38 cm3

), sampling depth in the mineral soil (10 to 15 cm; 4 to 6 in), 

and laboratory protocols of the 1992 project. A total of 

32 soil samples were collected. Samples were ovendried (105 oC until they reached a constant weight) 

and weighed. Bulk density is based on the fine earth 

fraction of the soil (in other words, coarse-fragments 

were removed) and fine-fraction bulk density calculated using the equations in Page-Dumroese and others 

(1999).

We compared the 2007 soil density values to the 

same reference samples (undisturbed) we used for 

the 1992 sampling. Using the same reference samples 

was necessary since it was difficult to find an undisturbed area where no previous impacts existed. There 

Paul Hancock, Kirby 

Self and Holly 

Boaz collect core 

samples in June 

2007.
USDA Forest Service RMRS-GTR-215. 2008. 3

was no reason that the original reference values of 

0.93 Mg m-3 would not still be applicable (based on 30 

core samples). Using the current Region 2 soil quality standards, a 15 percent increase from the reference 

stand bulk density yields a value of 1.07 Mg m-3 as the 

threshold value of compaction considered detrimental 

to stand productivity on this soil type.

In addition to collecting bulk density cores to estimate compaction levels, visual observations were 

made on soil structure. Of particular interest was the 

occurrence of platy soil structure and its possible use 

as an indicator of detrimental site impacts. Platy structure is defined as the arrangement of soil particles into 

aggregates that are flat horizontally (Schoeneberger 

and others 1998). Platy structure can be natural or it 

can be caused by excess trafficking.

Results and Discussion

1992 Pool Monitoring Project 

Summary

In 1992, a total of 233 soil samples were collected 

along 24 randomly selected transect points and azimuths (table 1). Transect Number 1 was disqualified 

since it fell on a designated road.

In Unit 5, 17.3 percent of the area was skid trails. 

This is generally higher than desirable on these sites. 

Usually, a total skid trail area of 6 percent to 10 percent 

in each harvest unit is preferred in ground-based logging to keep soil impacts within acceptable limits (<15 

percent of the area capable of growing trees). Table 2 

shows the summary of the areal extent of detrimental 

compaction by visual class. However, it is likely that 

some compaction existed in the stand prior to the 1991 

logging. We based this on the fact that even the undisturbed visual class had 2.31 percent (areal extent) 

of detrimental compaction. This could be the result of 

past logging that occurred in this area pre-1962. After 

years of inactivity, the forest floor may appear undisturbed but may mask underlying soil compaction.

A separate comparison (table 3) of the 1992 undisturbed bulk densities and the 1992 skid trail bulk 

densities yielded an average mean difference in bulk 

density between undisturbed sites and skid trails of 

0.09 Mg m-3 and is a change of 9 percent (standard 

error of 0.043). This amount of difference in mean 

bulk density is detectable from zero (p = 0.046). This 

means that there is significant difference between the 

1992 undisturbed bulk densities and the skid trail bulk 

densities.

2007 Monitoring Project Summary

Raw data and statistical analyses are contained in 

Appendix A. The two sample periods (1992 and 2007) 

cannot be compared in all aspects since the 2007 

sampling focused solely on the skid trail class. No conclusions could be drawn regarding the miscellaneous 

areas or undisturbed areas since we did not investigate 

these components. However, this re-sampling can set 

the stage for future monitoring investigations.

In 1992, the average bulk density of the skid trails 

was 1.02 Mg m-3 and was slightly less than that (1.01 

Mg m-3) in 2007 (table 4). Although the average values 

were less than the 1.07 Mg m-3 bulk density threshold (a 15 percent increase in bulk density), skid trails 

accounted for >6 percent of the area classed as detrimental compaction (table 2). The average difference 

in skid trail bulk density between 1992 and 2007 was 

0.012 with a standard error of 0.043. This amount of 

difference in mean bulk density is not detectable from 

zero (p = 0.73) so it would be inappropriate to interpret this result in a way that indicates that recovery on 

skid trails was detectable after 15 years.

Table 1. Areal extent (in percent) of each visual 

disturbance class for Unit 5 in 1992. Values are an 

average of 233 sample points.

Transect Skid

numbers Undisturbed Miscellaneous trails

------------------percent------------------

2 through 25 11.4 71.1 17.3

Table 2. Summary of detrimental compaction (in percent) by 

visual class.

Visual class Undisturbed Miscellaneous Skid trails Total

 ----------------------------percent---------------------------

2.31 12.12 6.89 21.32
4 USDA Forest Service RMRS-GTR-215. 2008.

The comparison between the 1992 undisturbed and 

the 2007 skid trail bulk densities (table 5) illustrates 

a small numerical reduction in skid trail bulk density 

between 1992 and 2007, but the reduction is too small 

relative to sampling variability to provide a definitive 

interpretation that recovery is occurring. The average 

difference between the bulk densities of the undisturbed sites in 1992 and skid trails in 2007 was 0.07, 

with a standard error of 0.042. This amount of difference in mean bulk density is weakly detectable from 

zero (p = 0.089).

The analyses above compare skid trail bulk densities within their respective populations. In USFS 

Region 2, compaction that exceeds the 1.07 Mg m-3 on 

this soil type is considered detrimental to vegetative 

growth. Based on 32 core samples collected in 2007, 

11 samples (34 percent) had detrimental compaction. 

This compares with the 1992 project that found 18 

of 42 samples (43 percent) of the skid trails to have 

detrimental compaction. Because of the differences 

in sample size and not having exact GPS coordinates 

from the original sample date, it is difficult to interpret 

whether the detrimental compaction is showing slight 

recovery from 1992 to 2007 or if the values are reflecting normal site variability.

Variability in Unit 5

For Unit 5, we assessed the distribution of bulk 

density cores in the undisturbed after sampling in 

1992 and in 2007. Figure 1 illustrates how the bulk 

density values shift to the right hand portion of the 

graph. This Figure shows that compaction does not 

occur uniformly (all one value). Rather, bulk density 

values shift from low to high as trafficking increases. 

This is similar to the shift in bulk densities noted on 

the LTSP sites (Page-Dumroese and others 2006). 

Since harvest activity ended, there is no evidence 

of skid trail use (legally or illegally) by vehicles for 

firewood gathering or other uses. The soil seems to 

reflect the original conditions left after the timber 

harvest.

Table 5. Comparison of bulk density in 2007 with the undisturbed bulk densities from 1992. Thirty two samples 

were collected in 2007 and 30 samples were collected in 1992 from the undisturbed areas.

Lower Upper Lower CL Upper CL

CL CL standard Standard standard Standard

Variable Mean Mean mean deviation deviation deviation error Min Max

Skid trail 2007 0.9439 1.0054 1.0669 0.1367 0.1705 0.2267 0.0301 0.717 1.368

Undisturbed 1992 0.8717 0.9317 0.9916 0.1279 0.1606 0.2159 0.0293 0.720 1.210

Difference (1-2) -0.011 0.0737 0.1580 0.1407 0.1658 0.2019 0.0421

Table 3. Comparison of 1992 undisturbed and skid trail bulk densities. Forty-three samples were collected in the 

skid trail and 30 were collected from the undisturbed areas.

Lower Upper Lower CL Upper CL

CL CL standard Standard standard Standard

Variable Mean Mean mean deviation deviation deviation error Min Max

Skid trail 1992 0.958 1.0173 1.0737 0.1589 0.1927 0.2449 0.0294 0.59 1.34

Undisturbed 1992 0.8717 0.9317 0.9916 0.1279 0.1606 0.2159 0.0293 0.72 1.21

Difference (1-2) 0.0002 0.0857 0.1712 0.1549 0.1803 0.2157 0.0429

Table 4. Average bulk density in the undisturbed and skid trail visual classes. 

Samples taken in 1992 and 2007.

1992 Undisturbed 1992 Skid trails 2007 Skid trails

--------------------------------Mg m3-------------------------------

Bulk density 0.93 1.02 1.01

Number of samples 30 43 32

Standard deviation 0.145 0.194 0.171
USDA Forest Service RMRS-GTR-215. 2008. 5

In an effort to determine where detrimental compaction might be more prevalent, we looked within the 

skid trails to see if the location of the most compaction 

was in the left rut (three samples exceeded standards), 

right rut (four samples exceeded standards) or the center of the skid trail (four samples exceeded standards). 

However, samples that exceeded the standards occurred equally across the skid trail.

Analysis of Platy Structure

Of the 32 samples collected in 2007, 22 exhibited 

platy structure. Of the 22 samples exhibiting platy 

structure, only six had detrimental compaction. Only 

one in three samples showed platy structure associated with detrimental compaction. On the other hand, 

in five samples, no platy structure was observed yet 

detrimental compaction was evident. The findings 

demonstrate that it is a complex challenge to evaluate detrimental soil compaction using observable platy 

structure. Other assessment tools would be necessary.

Growth-Limiting Bulk Density Analysis

None of the 32 samples collected in 2007 in 

Unit 5 exceeded growth-limiting bulk density values 

(Daddow and Warrington 1983) or the values defined 

in the R2 Supplement (USDA Forest Service FSH 

2509.18 1992) for a loam (1.40 Mg m-3). Soil texture 

is one of the most important properties which govern 

the growth-limiting bulk density because of overall 

mechanical resistance and pore-size distribution. In 

addition, key assumptions of growth-limiting bulk 

density are that (1) the soil has less than 10 percent 

coarse-fragment content (Unit 5 had ~20 percent), 

(2) <3 percent organic matter, and (3) the relationship 

0.6 0.8 1.0 1.2 1.4

0.0 0.5 1.0 1.5 2.0 2.5

Bulk density (g/cc)

Normal distribution density function

Undisturbed 1992

Skid trail 1992

Skid trail 2007

Figure 1. Distribution of bulk density cores taken from 

undisturbed areas and the skid trails (both samples dates).

Visual observations of platy 

structure were documented.
6 USDA Forest Service RMRS-GTR-215. 2008.

between root growth and bulk density were developed 

at or near field capacity (Daddow and Warrington 

1983). In addition, most of the data points used to develop the growth-limiting bulk density curves were 

from agricultural situations and may not be applicable 

to many forest sites. Over the past 16 years, more than 

350 individual core samples have been collected on 

the Rio Grande National Forest for range, recreation, 

and timber projects. None of the samples exceeded 

growth-limiting bulk density values for a loam, which 

is the dominant surface texture on the Rio Grande 

National Forest. The assumptions listed above may 

be key reasons why growth-limiting bulk densities are 

rarely detected.

Miscellaneous Areas

Areas that were identified as “miscellaneous areas” in the 1992 project were not sampled in the 2007 

project. This is because surface conditions in miscellaneous areas (places where the whole-tree harvester 

tracked into the stand) have either started to ameliorate 

over time or could not be observed on the ground (now 

covered with forest floor material). Miscellaneous areas actually accounted for most of the compaction in 

the entire stand by contributing 12.12 percent of the 

area impact. It is unknown as to how well this compaction recovered over time.

Summary

The results show that little to no recovery has taken 

place over 15 years since the 1992 sampling (or over 

16 years since the timber harvest occurred) based on 

bulk density samples. In addition, compaction considered detrimental to vegetation growth persists in 

2007, 16 years after logging. Our findings are consistent with the findings of LTSP study (Powers and 

others 2005). The LTSP study indicated that sites with 

low rates of recovery from extreme compaction were 

those in Idaho, Michigan, and Minnesota—all sites 

with frigid soil temperature regimes. It concluded 

that perhaps freeze and thaw cycles in cool, temperate, and boreal life zones are not particularly effective 

for ameliorating the impacts of soil compaction below 

10 cm. The Seitz soil series, on which harvest Unit 5 

occurs, is in the cryic temperature regime, which is 

colder than frigid and found in a boreal life zone. This 

temperature regime may also be ineffective at altering 

soil compaction.

Prevention of soil impacts is generally preferred 

over restoration measures. Careful design and spacing of skid trails can keep soil impacts within soil 

standards. Winter logging on snow or frozen conditions can also minimize soil impacts. Alternatively, 

operating on dry soil conditions can be useful in 

managing soil impacts. Although rehabilitation of 

compaction impacts was not studied, use of a winged 

subsoiler has been successfully used to ameliorate 

soil compaction concerns on this and other Forests 

in USFS Region 2. Subsoiling or other rehabilitation efforts can bring areas considered detrimentally 

disturbed below the threshold levels for both areal 

extent and compaction.

Management Implications

It is important for land managers to know if soil 

quality standards for their respective USFS Regions 

are being met prior to decisions to conduct salvage 

logging, thinning, or other timber harvest operations. 

On-site investigations and evaluations are essential 

and should be performed by qualified soil scientists 

or others trained in soil monitoring methods and protocols to assess the degree of soil impacts. Soil impact 

evaluations also provide analysis of potential cumulative effects to soils from project activities and whether 

projects would meet soil protection standards and 

design criteria in order to comply with the National 

Environmental Policy Act and National Forest 

Management Act requirements.

Curt Calkins prepares a site for soil sampling, June 1992.
USDA Forest Service RMRS-GTR-215. 2008. 7

In Unit 5, observations of platy structure were of 

limited value in assessing soil impacts on an areal 

basis. Soil assessments should employ a variety of 

tools that work for a given ecological area. The soil 

monitoring approach used for Unit 5 provides information regarding recovery of compaction in natural 

conditions of this boreal forest stand. This is one of a 

few assessments that evaluate longer-term recovery of 

soil compaction after harvest operations. However, it 

is not being advocated as a “rapid” field methodology 

because of the number of bulk density cores taken and 

site variability.

Growth-limiting bulk density values were never 

exceeded in Unit 5 or on other monitoring studies 

on the Rio Grande National Forest (Rawinski 2008). 

Growth-limiting bulk densities were also difficult to 

induce during plot compaction in the LTSP studies. 

Using growth-limiting bulk density or platy structure 

may not be effective monitoring tools for forest sites 

and other methods may be necessary to assess the impacts of forest harvest operations on soil conditions.

Acknowledgments

We gratefully acknowledge Foresters Kirby Self 

and Paul Hancock of the Divide Ranger District, Rio 

Grande National Forest, for providing sampling assistance to this project. Geologist Nicolas Sandoval 

and forestry aid Holly Boaz assisted with field data 

collection. Thanks for consultation are also due to 

Terry Craigg, former Soil Scientist of the Deschutes 

National Forest, and Steve Howes, Regional Soil 

Scientist in Region 6. Rudy King, Biometrician at the 

Rocky Mountain Research Station in Fort Collins, 

Colorado, also provided valuable assistance in the statistical analysis of data. Regional Soil Scientists Jeff 

Bruggink (Region 4), Tommy John (Region 2), and 

John Nesser (retired, Region 1) provided review of 

this study. Gratitude is also expressed to Tim Sullivan, 

former Region 2 Assistant Regional Soil Scientist, 

who provided friendship and leadership in the 1992 

Pool monitoring project.

Literature Cited

Curran, M.P.; Heninger, R.L.; Maynar, D.G.; Powers, R.F. 

2005. Harvesting effects on soils, tree growth and longterm productivity. In: Productivity of Western Forests: 

A forest products focus. Tech. Editors: Harrington, 

C.A.;Schoenholtz, S.H. Gen Tech Rep. GTR-PNW-642. 

Portland, OR: U.S. Department of Agriculture, 

Forest Service, Pacific Northwest Research Station. 

pp. 3-17.

Daddow, R.L.; Warrington, G.E. 1983. Growth-limiting soil 

bulk densities as influenced by soil texture. Watershed 

Systems Development Group. WSDG-TN-0005. 

Washington, DC: U.S. Department of Agriculture, Forest 

Service, 27 p.

Froehlich, H.A.; Miles, D.W.R.; Robbins, R.W. 1985. Soil 

bulk density recovery on compacted skid trails in central 

Idaho. Soil Sci. Soc. Am. J. 49: 1015-1017.

Howes, S.; Hazard J.; Geist, J.M. 1983. Guidelines for sampling some physical conditions of surface soils. Pacific 

Northwest Region. U.S. Department of Agriculture, 

Forest Service. 32 pages.

Liechty, H.O.; Shelton, M.G.; Luckow, K.R.; Turton, D.J. 

2002. Impacts of shortleaf pine-hardwood forest management on soils in the Ouachita Highlands: a review. 

South. J. Appl. For. 26: 43.51.

Page-Dumroese, D.S.; Jurgensen, M.F.; Brown, R.E.; Mroz, 

G.D. 1999. Comparison of methods for determining bulk 

densities of rocky forest soils. Soil Sci. Soc. Am. J. 63: 

379-383.

Page-Dumroese, D.S.; Jurgensen, M.F.; Tiarks, A.E.; 

Ponder, F., Jr.; Sanchez, F.G.; Fleming, R.L; Kranabetter, 

J.M.; Powers, R.F.; Stone, D.M.; Elioff, J.D.; Scott, 

D.A. 2006. Soil physical property changes at the North 

American Long-Term Soil Productivity sites: 1 and 5 

years after compaction. Can. J. For. Res. 36: 551-564.

Powers, R.F.; Scott, D.A.; Sanchez, F.G.; Voldseth, R.A.; 

Page-Dumroese, D.; Elioff, J.D.; Stone, D.M. 2005. The 

North American Long-Term Soil Productivity experiment: findings from the first decade of research. Forest 

Ecology and Management. 220: 31-50.

Rawinski, J.J. 2008. (Unpublished) Various monitoring 

notes and summaries from soil quality monitoring, Rio 

Grande National Forest.

Sands, R.; Greacen, E.L.; Gerard, C.J. 1979. Compaction 

of sandy soils in radiate pine forests: I. A penetrometer 

study. Aust. J. Soil Res. 17: 101-113.

Schoeneberger, P.J.; Wysocki, D.A.; Benham, E.C.; 

Broderson W.D. 1998. Field book for describing and 

sampling soils. Natural Resources Conservation Service, 

U.S. Department of Agriculture, National Soil Survey 

Center, Lincoln, NE.

Soil Survey Staff. 1999. Soil taxonomy: a basic system of soil classification for making and interpreting 

soil surveys. Washington, DC: U.S. Department of 

Agriculture, Natural Resource Conservation Service. 

U.S. Government Printing Office. 869 p.

Tiarks, A.E.; Haywood, J.D. 1996. Effects of site preparation and fertilization on growth of slash pine over two 

rotations. Soil Sci. Soc. Am. J. 60: 1654-1663.

USDA Forest Service. 1996. Land and resource management plan and environmental impact statement for the 

Rio Grande National Forest, Colorado. On file with the 

Rio Grande National Forest.

USDA Forest Service FSH 2509.18. Soil management 

handbook, R2 Supplement No. 2509.18-92-1. August 

15, 1992.
8 USDA Forest Service RMRS-GTR-215. 2008.

1992 Undisturbed 1992 Skid trail bulk 2007 Skid trail bulk

bulk density (Mg/m3) density (Mg/m3) density (Mg/m3)

0.72 0.59 0.72

0.72 0.61 0.72

0.72 0.68 0.74

0.73 0.73 0.76

0.74 0.73 0.80

0.75 0.76 0.84

0.76 0.79 0.85

0.79 0.80 0.86

0.80 0.86 0.87

0.84 0.89 0.88

0.85 0.89 0.89

0.86 0.91 0.95

0.87 0.92 0.98

0.87 0.92 1.01

0.92 0.96 1.02

0.92 0.97 1.02

0.94 0.98 1.03

0.96 1.00 1.03

0.96 1.03 1.05

1.00 1.04 1.05

1.03 1.05 1.05

1.03 1.05 1.07

1.10 1.05 1.09

1.10 1.05 1.11

1.11 1.07 1.16

1.13 1.07 1.19

1.15 1.10 1.19

1.16 1.10 1.21

1.21 1.11 1.21

1.21 1.12 1.22

1.12 1.25

1.13 1.37

1.13

1.16

1.19

1.21

1.22

1.23

1.27

1.29

1.30

1.33

1.34

Mean 0.93 1.02 1.01

Number samples 30 43 32

Standard deviation 0.161 0.193 0.171

APPENDIX A. Field Data and Statistical Analysis.
USDA Forest Service RMRS-GTR-215. 2008. 9

APPENDIX B. Pool Timber Sale Monitoring Site Rio Grande 

National Forest, Colorado.

Map 1. Pool monitoring site location.
10 USDA Forest Service RMRS-GTR-215. 2008.

Map 2. Diagrams of Unit 5 showing the portion of the Unit where the 1992 soil sampling occurred 
USDA Forest Service RMRS-GTR-215. 2008. 11

Map 3. Close-up of the layout of sample point distribution and numbering system 
12 USDA Forest Service RMRS-GTR-215. 2008.

Map 4. Distribution of skid trails within unit 5.

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private organizations, academic institutions, industry, and individuals. 

Studies accelerate solutions to problems involving ecosystems, range, 

forests, water, recreation, fire, resource inventory, land reclamation, 

community sustainability, forest engineering technology, multiple use 

economics, wildlife and fish habitat, and forest insects and diseases. 

Studies are conducted cooperatively, and applications may be found 

worldwide.

Station Headquarters

Rocky Mountain Research Station

240 W Prospect Road

Fort Collins, CO 80526

(970) 498-1100

Research Locations

Rocky

 Mountain

 Research Station

Reno, Nevada

Albuquerque, New Mexico

Rapid City, South Dakota

Logan, Utah

Ogden, Utah

Provo, Utah

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its 

programs and activities on the basis of race, color, national origin, age, disability, 

and where applicable, sex, marital status, familial status, parental status, religion, 

sexual orientation, genetic information, political beliefs, reprisal, or because all 

or part of an individual’s income is derived from any public assistance program. 

(Not all prohibited bases apply to all programs.) Persons with disabilities who 

require alternative means for communication of program information (Braille, 

large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 

720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, 

Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, 

DC 20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA 

is an equal opportunity provider and employer.

Flagstaff, Arizona

Fort Collins, Colorado

Boise, Idaho

Moscow, Idaho

Bozeman, Montana

Missoula, Montana