Susceptibility of volcanic ash-influenced soil in northern Idaho to mechanical compaction

10 Pages·1993·0.47 MB·English

by  Page-Dumroese, Deborah S

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^ ~j> United States Susceptibility of Volcanic
Department
of Agriculture
Forest Service Ash-Influenced Soil in
Intermountain
Research Station Northern Idaho to
Research Note
INT-409 Mechanical Compaction
February 1993
Deborah Page-Dumroese
S.
Abstract—Timber harvesting and mechanical site prepa- (Geist and Cochran 1991). Their undisturbed bulk
ration can reduce site productivity ifthey excessively dis- density is about 0.70 g/cm3, porosity 77 percent, coarse
turb or compact the soil. Volcanic ash-influenced soils with fragments 20 percent, and available water 25 percent
low undisturbed bulk densities and rock content are particu- (see Geist and Cochran 1991).
larly susceptible. This study evaluates the effects ofhar- Froehlich and others (1985) note a predictable de-
vesting and site preparation on changes inthe bulk density cline in seedling height growth as soil bulk density
ofash-influenced forest soils in northern Idaho. Three dif- increases. They also conclude that the effects ofcom-
ferent levels ofsurface organic matter were studied. Soil paction can last up to 45 years. Soil compaction in a
samples were taken before and after harvestingto deter-
central Oregon clearcut caused a significant decline
mine the extent and depth ofcompaction. Soil bulk densi-
(p < 0.05) in seedling growth after 5 years (Cochran
ties increased significantly after extensive compactionfrom
site preparation, especially when little logging slash and and Brock 1985). Soil compaction also lowers soil
surface organic matter were left onthe soil surface. As site porosity (Dickerson 1976; Moehring and Rawls 1970)
preparationintensity increased, bulk densityincreased sig- and hydraulic conductivity (Gent and others 1984).
nificantly at greater depths in the soil profile. Although These studies indicate timber harvesting increases
ash-influenced soils have naturallylow bulk densities, they compaction. Relatively little information, however, re-
can easily be compacted to levels that limit growth. This lates the quantity ofresidual organic matter and the
experimental site hasbeen designated as part ofthe Forest intensity ofsite preparation to compaction levels in
Service's national long-term site productivity study into the the soil profile before and after harvest. This study
impacts oforganic matter depletion and soil compaction on compares soil bulk densities before and after timber
stand development.
harvest for three intensities ofsite preparation and
three levels oforganic matter conservation on a vol-
Keywords: bulk density, forest productivity, ash-cap canic ash soil in northern Idaho.
soils, logging, logging effects, soil density,
site preparation METHODS
This study was conducted on a bench adjoining the
Land managers have long been concerned that tim- Priest River at the Priest River Experimental Forest,
ber harvesting and mechanical site preparation might Priest River, ID. The study area receives about 83.8 cm
harm forest productivity. The Intermountain West ofprecipitation annually, with a mean annual tempera-
has extensive areas offorested land on volcanic ash ture of6.6 °C (Wellner 1976). The habitat type is clas-
soils (Geist and others 1989). These areas are highly sified as Tsuga heterophylla/Clintonia uniflora (Cooper
productive, but prone to compaction because they and others 1991). The soil has a silt loam surface
have a low volume weight (weight-to-volume ratio) layer 28 to 38 cm thick derived from Mount Mazama
and relatively few coarse fragments in the soil profile volcanic ash. The subsoil is 50 to 75 cm thick. It is a
silty clay loam derived from glacial lacustrine (lake)
sediments. These are underlain at depths of60 to
100 cm by gravelly to very gravelly sands and sandy
Deborah S. Page-Dumroeseisresearchsoil scientistatthe Intermountain loams deposited by alluvial processes. The soil is a
ResearchStation'sForestrySciences Laboratory, Moscow, ID.
Theuseoftradeorfirmnamesinthispublicationisforreaderinforma- medial, frigid Ochreptic Fragixeralf(Mission series).
tion and does notimplyendorsementbytheU.S. DepartmentofAgriculture Before harvest, the site consisted ofa well-stocked
ofanyproductorservice.
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stand ofabout 90-year-old western white pine (Pinus the first tractor pass to prevent organic and mineral
monticola Dougl. ex D. Don), western hemlock (Tsuga components from being mixed. The organic matter
heterophylla [Raf.] Sarg.), Douglas-fir (Pseudotsuga was then evenly redistributed on the plots.
menziesii var. glauca [Beissn.] Franco), and western In each 0.8-ha plot, 16 locations were established
larch (Larix occidentalis Nutt.). In the past, the site on a 20-m grid. At each grid point bulk density sam-
was part ofthe PriestRiverArboretum. Approximately ples were taken with a core sampler. Samples were
40 years ago some western white pine was selectively taken at to 4-cm, 8 to 16-cm, and 16 to 20-cm depths.
harvested, creating one skid trail. This skid trail be- Soil moisture during site preparation averaged 25
came part ofthe buffer around the treatment plots. percent.
This site was divided into nine 0.8-ha plots sur- The differences in the means ofsoil bulk densities
rounded by a 200-m buffer. Trees were directionally before and after harvest were compared at the 95
felled and skidded along a central skid trail or from the percent confidence interval. A paired t test was used
plot boundaries to prevent compaction during harvest- to compare means.
ing. The treatments followed a three-by-three factorial
design ofthree levels ofresidual organic matter and RESULTS AND DISCUSSION
three levels ofsite preparation, yielding nine types of
treatments. Organic matter treatments were: (1) bole Figure 1 shows the effects ofharvest method and site
only removal in which the limbs were lopped on the preparation on soil bulk densities. When harvest activ-
plot before skidding, (2) bole and crown removal in ities were restricted to the designated skid trail, the
which the entire tree was removed from the plot, and soil densities were no greater after harvest than before.
(3) bole and crown removal and surface organic mat- However, as site preparation encompassed more of
ter displacement in which entire trees were removed the site, the number ofpasses by heavy equipment
and slash and surface organic matter were displaced increased, or smaller amounts oforganic residue were
from the plot. Compaction levels consisted of(1) none, left on the site, bulk density began to increase signifi-
(2) moderate, and (3) extensive. Compaction-free plots cantly. The average soil bulk density increased from
did not have any equipment on them during harvesting 0.65 to 0.81 g/cm3 with extreme compaction whenjust
or site preparation. Moderate compaction was achieved the boles were removed. But even after harvest, the
by driving a Grappler log carrier over the plots twice. average bulk density was still much lower than that
Extensive compaction was obtained with four passes ofmany coarse-textured soils in this region, which can
with a D-6 Caterpillar tractor. On compacted plots average greater than 1.0 g/cm3 However, bulk den-
.
with surface organic matter debris was removed with sity increased more than 20 percent with four vehicle
Q
Preharvest
1.0
Postharvest
^
0.8
N = No compaction
E ll >: 1 M = Moderate compaction
u
3 E = Extensive compaction
<2
0.6
CO
m
0.2
i
0.0
N M E N M E N M E
Bole only removal Bole and crown Bole, crown, and
removal surface organic
matter removal
—
Figure 1 The effects of timber harvesting and site preparation soil
bulk density, averaged for three soil depths.
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—
Table 1 The effects of harvesting and site preparation on average bulk density at three soil depths
Preharvest Postharvest
Treatment 0-4 cm 8-12 cm 16-20 cm 0-4 cm 8-12 cm 16-20 cm
g/cm*
No site preparation
Bole only removal 0.43a1 0.67a 0.75a 0.48a 0.71a 0.73a
Bole and crown removal .46a .61a .69a .50a .68a .70a
Bole and crown removal .53a .68a .77a .63a .76a .76a
and surface organic
matter displacement
Moderate site preparation
Bole only removal .71a .78a .81a .71a .82a .84a
Bole and crown removal .60a .67a .78a .70a .78b .83a
Bole and crown removal .66a .78a .80a .78a .81a .82a
and surface organic
matter displacement
Extensive site preparation
Bole only removal .54a .69a .75a .71b .71a .84a
Bole and crown removal .55a .74a .72a .74b .85a .86b
Bole and crown removal .65a .75a .84a .84b .85a .91b
and surface organic
matter displacement
1Different letters indicate significantdifferences between pre- and postharvest samples for each depth (p< 0.05).
passes. Large increases in bulk density have been re- matter removal treatment. In the bole only removal
ported to a depth ofabout 5 cm with the first vehicle treatment, bulk density increased significantly only
pass over the soil (Kroger and others 1984; Miles and at the surface. In the moderate site preparation treat-
others 1981). ments increases in bulk density were rarely signifi-
Leaving woody residue and surface organic matter cant. However, surface bulk density increased more
on the site protects mineral soil from detrimental than 20 percent after two passes ofthe Grappler when
compaction; it also reduces erosion (Gilmour 1977; the bole and crown and bole, crown and surface organic
Rice and Datzman 1981) and maintains soil nutrition matter were removed. On volcanic ash soils in Oregon
(Page-Dumroese and others 1991) and soil microbe soil bulk density at the to 20-cm depth increased 35
populations (Jurgensen and others 1991). InVermont, percent after harvesting and site preparation (Davis
bark mulch applied on a sandy loam soil effectively 1992). Bulk density increases proportionally with the
reduced increases in bulk density from activities that square root ofthe number ofpasses over the same
compacted the soil (Donnelly and Shane 1986). area (Reisinger and others 1988). Most soil damage
In this study, soils were compacted in the spring is seen after one to four passes (Gent and others 1984;
when the soil moisture content was about 25 percent. Kroger and others 1984).
Soil moisture content affects the compactability not Compaction on some volcanic ash soils persists for
only ofcohesive soils, but also ofnoncohesive soils, decades (Froehlich and others 1985), depending on
in which compaction can occur throughout a wide the degree ofinitial change. The degree ofinitial
range ofsoil moisture contents (Davis 1992). Effects change depended on soil texture, moisture, structure,
similar to those reported in this study could be ex- number ofmachine passes, and loading and operator
pected throughoutmost ofthe growing season on non- skills (Geist and Cochran 1991). On many sites in
cohesive soils. the Inland Northwest, deep snow cover early in the
Site preparation compacted soil deep in the soil pro- winter limits the amount ofsoil recovery from frost
file. Table 1 shows significant increases in bulk den- action. The soils in this study have less than 20 per-
sity at both the to 4-cm and 16 to 20-cm depths after cent clay content by weight and very little shrink-
extensive site preparation. There were no significant swell potential. Therefore, compaction within the
differences at the 8 to 12-cm depth. However, at the soil profile may remain high for many decades until
16 to 20-cm depth significant increases in bulk density a new stand is ready to be harvested.
were associated with both the bole and crown removal Compaction, as measured by changes in bulk den-
treatment and the bole, crown, and surface organic sity, has been shown to reduce the growth ofmany
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commercial timber species. On well-drained soils in UT: U.S. Department ofAgriculture, Forest Ser-
Oregon formed from Mount Jefferson ash (Cochran and vice, Intermountain Research Station. 143 p.
Brock 1985), compaction reduced the height ofponde- Davis, S. 1992. Bulk density changes in two central
rosa pine (Pinusponderosa Dougl. ex Laws.) seedlings Oregon soils following tractor logging and slash pil-
for 5 years after planting. Compaction or displacement ing. Western Journal ofApplied Forestry. 7: 86-88.
oforganic material significantly reduced one or more Dickerson, B. P. 1976. Soil compaction after tree-length
growth variables of 15 to 25-year-old lodgepole {Pinus skidding in northern Mississippi. Soil Science Soci-
contorta Dougl. ex Loud.) and ponderosa pine in north- ety ofAmerica Journal. 40: 965-966.
central Idaho (Clayton and others 1987). Froehlich Donnelly, J. R.; Shane, J. B. 1986. Forest ecosystem
(1979) has suggested compaction may reduce seed- responses to artificially induced soil compaction. I.
ling growth for at least 14 years. Soil physical properties and tree diameter growth.
Canadian Journal ofForest Research. 16: 750-754.
MANAGEMENT IMPLICATIONS Froehlich, H. A. 1979. Soil compaction from logging
equipment: effects on growth ofyoung ponderosa
Given the slow rate ofnatural soil recovery, land pine. Journal of Soil and Water Conservation. 34:
managers are concerned about long-term site degra- 276-278.
dation as soils are compacted or displaced. Direct Froehlich, H. A.; Miles, D. W. R; Robbins, R. W. 1985.
losses in productivity are often difficult to measure. Soil bulk density recovery on compacted skid trails in
Reduced seedling growth or long-term losses in soil central Idaho. Soil Science Society ofAmerica Jour-
nutrient content, porosity, and infiltration depend nal. 49: 1015-1017.
on the percentage ofarea affected and the rate ofthe Geist, J. M.; Cochran, P. H. 1991. Influences ofvolcanic
soil's recovery (Clayton and others 1987). Productiv- ash and pumice deposition on productivity ofwestern
A
ity declines associatedwithcompaction are reversible, interior forest soils. In: Harvey, E.;Neuenschwander,
—
given enough time for recovery (Froehlich and others L. F., comps. Proceedings management and produc-
1985). While reduced growth associated with soil dis- tivity ofwestern-montane forest soils; 1990 April
placement is more difficult to quantify, it may result 10-12; Boise, ID. Gen. Tech. Rep. INT-280. Ogden,
in irreversible long-term impacts (Harvey and others UT: U.S. Department ofAgriculture, Forest Service,
1989). Geist and others (1989), Froehlich (1979), and Intermountain Research Station: 82-89.
K
Davis (1992) suggest shifting harvest strategies to- Geist, J. M.; Hazard, J. W.; Seidel, W. 1989. Assess-
ward the use ofdesignated skid trails, directional ing physical conditions ofsome Pacific Northwest
felling, and line pulling to reduce the area affected. volcanic ash soils after forest harvest. Soil Science
In some locations, use ofa grapple-piler to pile logs Society ofAmerica Journal. 53: 946-950.
can reduce compaction because grapple-pilers apply Gent, J. A., Jr.; Ballard, R.; Hassan, A. E.; Cassel,
less pressure on the ground than crawler-tractors D. K. 1984. Impact ofharvesting and site prepara-
used for bulldozer-piling. Leaving the tops oftrees tion on physical properties ofPiedmont forest soils.
and surface organic matter on the site also may re- Soil Science Society ofAmerica Journal. 48: 173-177.
duce the amount ofcompaction. With the increasing Gilmour, D. A. 1977. Logging and the environment,
emphasis on uneven-aged management, the effects of with particular reference to soil and stream protec-
multiple-stand entries on compaction ofthese soils tion in tropical rainforest situation. In: Conserva-
will have to be assessed. tion guide 1: guidelines for watershed management.
Rome: Food andAgriculture Organization: 223-225.
REFERENCES Harvey, A. E.; Meurisse, R. T.; Geist, J. M.; [and oth-
ers]. 1989. Managing productivity processes in the
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Clayton, J. L.; Kellogg, G.; Forrester, N. 1987. Soil Inland Northwest mixed conifers and pines. In:
disturbance-tree growth relations in central Idaho Perry, D. A; [and others], eds. Maintaining the long-
clearcuts. Res. Note INT-372. Ogden, UT: U.S. De- term productivity ofPacific Northwest forest eco-
partment ofAgriculture, Forest Service, Intermoun- systems. Portland, OR: Timber Press: 164-184.
tain Research Station. 6 p. Jurgensen, M. F.; Tonn, J. R.; Graham, R. T.; Harvey,
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Cochran, P. H.; Brock, T. 1985. Soil compaction and A. E.; Geier-Hayes, 1991. Nitrogen fixation in
initial height growth ofplanted ponderosa pine. forest soils ofthe Inland Northwest. In: Harvey,
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Res. Note PNW-434. Portland, OR: U.S. Depart- E.; Neuenschwander, L. F., comps. Proceedings
ment ofAgriculture, Forest Service, Pacific North- management and productivity ofwestern-montane
west Forest and Range Experiment Station. 4 p. forest soils; 1990 April 10-12; Boise, ID. Gen. Tech.
Cooper, S. V.; Neiman, K. E.; Roberts, D. W. 1991. Rep. INT-280. Ogden, UT: U.S. Department ofAg-
Forest habitat types ofnorthern Idaho: a second riculture, Forest Service, Intermountain Research
approximation. Gen. Tech. Rep. INT-236. Ogden, Station: 101-109.
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Kroger, J. L.; Burt, E. C; Trouse, A. C, Jr. 1984. Skid- forest soils; 1990 April 10-12; Boise, ID. Gen. Tech.
der tire size vs. soil compaction in soil bins. Trans- Rep. INT-280. Ogden, UT: U.S. Department ofAg-
actions ofthe American Society ofAgricultural En- riculture, Forest Service, Intermountain Research
gineers. 27: 655-669. Station: 95-100.
Miles, J. A.; Hartsough, B. R.; Avalani, P.; Chancellor, Reisinger, T. W.; Simmons, G. L.; Pope, P. E. 1988.
W. J. 1981. A soil compaction study on the Blodgett The impact oftimber harvesting on soil properties
Experimental Forest. In: Forest regeneration: Pro- and seedling growth in the South. Southern Jour-
ceedings ofthe symposium on engineering systems nal ofApplied Forestry. 12: 58-67.
for forest regeneration; 1981 March 2-6; Raleigh, NC. Rice, R. M.; Datzman, P. A. 1981. Erosion associated
St. Joseph, MI: American Society ofAgricultural with cable and tractor logging in northwestern
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Moehring, D. M.; Rawls, I. W. 1970. Detrimental ef- Hydrology. 132: 362-374.
fects ofwet weather logging. Journal ofForestry. Wellner, C. A. 1976. Frontiers offorestry research -
68: 166-167. Priest River Experimental Forest, 1911-1976.
Page-Dumroese, D.; Harvey, A.; Jurgensen, M.; Ogden, UT: U.S. Department ofAgriculture, For-
Graham, R. 1991. Organic matter function in the est Service, Intermountain Forest and Range Ex-
western-montane forest soil system. In: Harvey, periment Station. 148 p.
A. E.; Neuenschwander, L. F., comps. Proceedings
management and productivity ofwestern-montane
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