Effects of forest harvest on soil carbon

DISCUSSION The Chronosequence Approach

h is study investigated forest harvest ef ects using the dis- turbance chronosequence approach, where disturbed sites are compared to spatially distinct control sites. h e basic assump- tion of disturbance chronosequences is that the only dif erence between sites should be their disturbance regime, and that all

Fig. 4. The C/N variation in proi les of (a) control plots, (b) cleared Fig. 3. Average C stock in the soil proi les of control, cleared, and

plots, and (c) regenerating plots. Mean (thicker line) is shown with regenerating plots.

90% coni dence limits.

www.soils.org/publications/sssaj

(PC1–PC3) for mineral horizon analysis. The last line shows

35 to 150% change.

the percentage variance explained by each factor. The highest coefi cients are in bold font.

Soil Organic Carbon

PC1

PC2 PC3

Soil organic C concentration in the mineral subsoil was sig- Variables

SOM content

SOM immaturity

nii cantly higher in cleared plots relative to control. h is increase

SOC†

was not likely due to mechanical mixing since physical proi le dis-

turbance was minimal. Mineral horizon boundaries showed no

C/SOM‡

evidence of disruption and the C content of the overlying E hori-

Al p §

zon was constant. A more likely explanation involves a temporary

Fe p §

0.41 0.08 intensii cation of organic matter illuviation immediately at er –0.19

Moisture¶

0.57 harvest (Kalbitz et al., 2004; Morris, 2009; Snyder and Harter, –0.45 e

CEC :C#

1985). h e importance of dissolved C transport was supported 14%

Variance explained

† Soil organic carbon concentration.

by the high correlation between SOC and Al

2 p + Fe p (r = 0.69,

‡ Carbon to nitrogen and carbon to soil organic matter ratios.

p < 0.0001) (Rasse et al., 2006). Decomposing roots may also

§ Pyrophosphate-extractable aluminum and iron.

contribute SOM to the subsoil. ¶ Gravimetric moisture content.

# Effective cation exchange capacity to carbon ratio.

h e SOC concentration was similar in control and regen- erating plots throughout the soil proi le, suggesting that SOC

Kleber et al., 2005; Mikutta et al., 2006; Rasmussen et al., 2006; gains were not retained or that older C was metabolized. h is is a

Scheel et al., 2007; Schmidt et al., 2000). Pari tt (2009) noted surprising i nding since spodic horizons are known to stabilize C

that SOM generally interacts rather slowly with minerals while by interaction with minerals and metals (Eusterhues et al., 2005;

Buurman et al. (2007) suggested that mineral protection did not act on primary organic matter, so that fresh inputs of organic matter to the illuvial horizons are not necessarily stabilized.

In the mineral soil, most changes occurred in SOM associ- ated with the sand fraction. h is coni rms that sand-sized SOM is the most sensitive to changes in land management (Gregorich et al., 2006). Sand-sized SOM is not protected by interaction with minerals (Zinn et al., 2007) and is susceptible to decompo- sition. In contrast, SOM associated with the silt and clay fraction was comparatively constant across treatments, suggesting that it contains mostly mineralogically, chemically, and biochemi- cally stabilized SOC (von Lützow et al., 2007). Organic matter associated with the clay fraction showed the least relative varia- tion, supporting the hypothesis that the clay fraction was satu- rated with SOM (Gulde et al., 2008; Six et al., 2002). h is is ex- pected in soils with low clay content and few complexation sites

Fig. 5. The C/N ratio as a function of soil organic carbon (SOC) in (a) the organic layer and (b) the mineral soil. The relationship between

Fig. 6. Distribution of control, cleared and regenerating samples SOC and C/N ratio was similar in both cleared and regenerating plots

along the i rst (PC1) and third principal components (PC3) for the (grouped under “harvested” for clarity).

i rst spodic horizon (Bs1).

Soil Science Society of America Journal

(Borchers and Perry, 1992). h e C/(Al+Fe) p ratio also remained Carbon and N stock comparisons with other sites should there- essentially constant at ~5. h is constant and relatively narrow C/

fore be considered with caution.

metal ratio suggests that in the subsoil, metals are present in suf-

i cient amounts for humus to reach its maximum metal sorptive

Organic Matter Composition

capacity, and probably the maximum protection that can be af-

Indicators of Decomposition

forded by metal complexation. Organic matter in regenerating plots generally had lower Variations in total proi le C stock were not statistically

C/N and C/SOM ratios relative to control. h is suggests in- signii cant, due in part to the dif erent behavior of organic and

creased organic matter decomposition and maturation at er har- mineral layers. Forest l oors of regenerating plots had a higher C

vest (Dai et al., 2001; Hannam et al., 2005; Kalbitz et al., 2004), stock than control plots, suggesting that the gradual conversion

with the C/N and C/SOM ratios decreasing as C is preferentially of living biomass into detrital pools and subsequent incorpora-

lost from SOM ( Johnson, 1995). In the forest l oor, the N/SOM tion into the forest l oor outweighed decomposition, leaching,

ratio was signii cantly higher in regenerating than in cleared and and translocation losses. In control plots, the forest l oor only

control stands, which may indicate intense oxidation. accounted for a quarter of proi le SOC, suggesting tight nutri-

Several factors are likely to enhance organic matter decom- ent cycling with rates of loss through decay and transfer approxi-

position at er disturbance (Spielvogel et al., 2006). h e allevia- mately equal to those of gain from biomass (Simonson, 1959). In

tion of summer drought may contribute to higher decomposi- regenerating stands, the forest l oor accounted for almost half of

tion rates (Niinistö et al., 2011). In Roberts Creek, we observed proi le SOC. Organic matter in the forest l oor is more suscep-

a higher soil moisture content in the topsoil of cleared plots rela- tible to degradation or mobilization due to the lack of protection

tive to control during sampling in late summer, possibly due to a by interaction with the mineral phase, and is more vulnerable to C

decrease in canopy interception and vegetation uptake (Bekele losses following harvest than the mineral soil (Nave et al., 2010).

et al., 2007). In regenerating plots, forest l oor moisture content remained higher than in control, perhaps rel ecting incomplete

Total Nitrogen

canopy closure. It should, however, be noted that these moisture Nitrogen stocks in the overall proi les of cleared and regen-

measurements only represent one point in time and are not likely erating plots were not signii cantly dif erent than in control. h is

to be representative of year-round conditions. Soil temperature contrasts with many studies of hardwood forests, which reported

is also likely to increase at er harvest as a result of increased so-

a signii cant decrease in soil N content for 5 to 15 yr at er clear- lar irradiation ( Johnson et al., 1985). Finally, fresh needles and cutting (Federer, 1984; Hendrickson et al., 1989). In the forest

early successional litter may have higher N content and be less l oor of regenerating plots, N stocks were higher than in control,

recalcitrant than mature forest litter (Covington, 1981). In likely due to inputs of detrital organic matter. In the mineral soil,

Roberts Creek, we observed active growth of i reweed in cleared retention of dissolved N by reactive mineral phases such as fer-

plots and a few N 2 -i xing alders (Alnus rubra Bong.) in regen- rihydrite and imogolite-type material, which are abundant in the

erating plots, which may contribute easily degradable organic subsoil (Grand and Lavkulich, 2008), may have prevented more

matter to the soil (Bradley et al., 2001) and exert a priming ef- signii cant losses. Even though N stocks were largely conserved

fect on existing soil organic matter (Crow et al., 2009; Fontaine over the timeframe of the study (15 yr), subsoil N stocks were

et al., 2007). h ese conditions can stimulate microbial activity signii cantly lower in regenerating than in cleared plots. h is

(Gabriel and Kellman, 2011). On the other hand, Prescott et trend could extend into the future, which could exacerbate N

al. (2000) reported that forest l oor material lost mass at similar limitation for regenerating forests (Hendrickson et al., 1989).

rates in forests and clearcuts, but pointed out that the response Since bulk density was estimated from depth and SOM

of decomposition to clear-cutting is highly variable and cannot concentration rather than being directly measured, the C and

be generalized.

N stocks reported here are subject to some error. De Vos et al. (2005) reviewed the predictive quality of 12 models for bulk

Carbon and Nitrogen Relations

density estimation, and found that all models produced underes-

h e C/N depth proi le dif ered markedly between treat- timates of i eld bulk density. Underestimation error was up to 9

ments. h e C/N ratio decreased rather constantly with depth in to 36% (Boucneau et al., 1998; De Vos et al., 2005). h e uncer-

control plots but showed sharp dif erences between horizons in tainty introduced by bulk density estimates is, however, expected

cleared plots. h is suggests that forest harvest disrupted a pre- to be moderate compared to the variability in coarse fragment

existing steady state of organic matter maturation. In the forest content and C concentration (Holmes et al., 2012). Skid trails,

l oor, the mean C/N value of cleared plots remained similar to tracks, and landings sites were avoided and soil compaction was

control values while the variance was signii cantly higher (p = not likely to be an important factor at sampled sites. Another

0.02 by Levene’s test for homoskedasticity). We propose that source of uncertainty are coarse fragments, which were not ana-

this higher variance but constant mean could result from vary- lyzed for C content but have been shown to contain between <1

ing proportions of fresh organic matter inputs from logging slash and 25% of SOC (Zabowski et al., 2011). h is suggests that the

and increased maturation of existing organic matter. In the E ho-

C and N stocks presented here may be conservative estimates. rizon, the C/N ratio was lower in cleared plots than in control,

www.soils.org/publications/sssaj

af ected by disturbance. the mineral soil and changes in bulk organic matter quality sug- Treatment also af ected the relationship between SOC

gesting the prevalence of mature SOM that is more oxidized and concentration and the C/N ratio. In control plots, there was no

bears a larger number of functional groups. relation between SOC and C/N, in accordance with the obser- vation of Waksman (1924), who noted that soils tend to achieve

Podzolization and Soil Organic Matter Dynamics

a relatively stable C/N ratio over time. In cleared and regenerat- Because SOM translocation is one of the main soil-forming ing plots however, there was a positive relationship. h is corre-

factors in Spodosols (Lundström et al., 2000; Petersen, 1976), sponds to a “nutrient dilution ef ect” (McGroddy et al., 2004),

observed changes in SOM dynamics were likely a product of the with SOC concentration increasing more rapidly than N con-

interaction between the land disturbance and podzolization pro- centration in organic-rich samples. On the other hand, samples

cesses. h e increase in SOC concentration in Bs-BCg horizons low in SOM also had a low C/N ratio, consistently with the idea

of cleared plots and concomittant increase in pyrophosphate- that decomposition reduces both the amount of organic matter

extractable metals suggests that illuvial accumulation of SOM in and the C/N ratio. h is suggests that forest harvest disrupted

the subsoil may have temporarity increased at er harvest. Possible the steady-state relations observed in undisturbed plots (Chaer

causes include an increase in ef ective precipitation and result- et al., 2009).

ing increase in soil moisture, and the ef ect of large additions of fresh SOM to the litter layer as logging slash. Decomposition of

Implications

the litter layer generates mobile low-molecular weight organic

h e soil C/N ratio generally shows an inverse relationship compounds involved in SOC and metal translocation to the with net nitrii cation, with a C/N ratio of 25 to 30 in the top-

subsoil (Buurman and Van Reeuwijk, 1984; De Coninck, 1980; soil generally considered to be a threshold below which net ni-

Petersen, 1976).

trii cation and nitrate leaching may take place (Gundersen and

h e increased illuviation of SOC to the mineral subsoil af- Rasmussen, 1990; Gundersen et al., 1998). In control sites, the

ter harvest may improve soil resilience to the biochemical ef ects C/N ratio in the uppermost layers (Oe+Oa and E horizons) was

of forest harvest (Strahm et al., 2009). In Roberts Creek, the high, suggesting that these soils were not actively nitrifying. In

translocation of dissolved C, Al, and Fe species to the subsoil and cleared and regenerating plots however, the C/N ratio in the E

their subsequent precipitation is likely to have made a signii cant horizon averaged 21 (range 14–28). In the forest l oor, regen-

contribution to the retention of SOM and associated nutrient erating plots had a signii cantly lower C/N ratio than control,

retention capacity in proi les of cleared plots. averaging 29 on average (range 24–42). h is suggests that at least

h e abundance of logging slash thus appeared to be one some of the proi les from cleared and regenerating plots may re-

of the key to the conservation of SOC stocks both in the forest lease nitrate (Hazlett et al., 2007). Acid soils generally have high

l oor and in the subsoil at er harvest. Whole-tree harvesting is N release rates because the N requirement of fungi tends to be lower

currently not a widespread forestry practice in British Columbia, than that of bacteria (Kooijman and Martinez-Hernandez, 2009).

but may receive growing consideration in the future as the de-

h e CEC e /C ratio is an indicator of organic exchange site mand for biomass to produce bioenergy increases. By reducing density, and was signii cantly higher in illuvial horizons of regen-

the amounts of logging slash inputs, whole-tree harvesting is erating plots compared to cleared and control stands. h e pH

likely to decrease ecosystem resilience to the ef ects of logging. was constant or slightly lower in cleared and regenerating plots than in control (data not shown), implying that much of the

CONCLUSIONS

increase in the CEC e /C ratio was due to actual changes in the We found that clearcut harvesting of coastal British character of SOM. Changes may include increased oxidation and

Columbia Douglas i r stands inl uenced SOM content, distribu- increased density of oxygen-bearing functional groups such as

tion, and bulk composition in underlying Spodosols. Our results

suggest that the soils’ response to harvest included two stages. ratio denotes SOM of high maturity and sorptive capacity

carboxl and phenolic groups ( Johnson, 1995). A high CEC e /C

h e i rst stage was characterized by an increase in C stock in the (Miralles et al., 2009) that may help retain nutrients on-site.

forest l oor and an increase in SOC concentration in the mineral subsoil, likely resulting from the gradual assimilation of logging

Integrated Effects of Forest Harvest

slash, SOC illuviation, and root decay. h e second stage was

h e principal component analysis showed that the main characterized by SOM losses from the mineral soil and changes dif erence between control and cleared plots was the amount of

in bulk organic matter quality suggesting an increased degree SOC, while regenerating plots were characterized by a change in

of decomposition. h e sand-sized fraction recorded the largest bulk organic matter composition. h is suggests that the response

variations in SOC concentration between treatments, while the to harvest includes two stages. h e i rst stage was characterized

clay fraction had a comparatively constant SOC concentration, by SOM gains, probably resulting from the gradual assimilation

suggesting that there was no net formation of new organo-min- of logging slash (Lee et al., 2002), increased translocation of

eral complexes and that new SOM inputs were not stabilized. dissolved C to mineral horizons (Rubino et al., 2010) and root

h e majority of the C stock was located in the mineral subsoil

Soil Science Society of America Journal Soil Science Society of America Journal

E.W. Sulzman. 2009. Increased coniferous needle inputs accelerate decomposition of soil carbon in an old-growth forest. For. Ecol. Manage.

followed changes in illuvial horizons. Studies of C dynamics in

258:2224–2232. doi:10.1016/j.foreco.2009.01.014

spodic soils should therefore take into account the entire thick-

Dai, K., C. Johnson, and C. Driscoll. 2001. Organic matter chemistry and

ness of illuvial horizons. When considering the entire solum, for-

dynamics in clear-cut and unmanaged hardwood forest ecosystems.

est harvesting was not accompanied by a signii cant variation of Biogeochemistry 54:51–83. doi:10.1023/A:1010697518227

D’Anjou, B. 2002. Roberts creek study forest: Harvesting, windthrow and

SOC stocks up to 15 yr at er cutting. Changes in the C/N depth

conifer regeneration within alternative silvicultural systems in douglas-i r

proi le, correlation between SOC and C/N and partition of SOC be-

dominated forests on the sunshine coast. Rep. TR-018. Research Section,

tween the forest l oor and mineral soil however provided indications Vancouver Forest Region, B.C. Ministry of Forestry, Nanaimo, BC.

De Coninck, F. 1980. Major mechanisms in formation of spodic horizons.

that the preexisting steady state between SOM inputs and decomposi-

Geoderma 24:101–128. doi:10.1016/0016-7061(80)90038-5

tion had been disrupted. A study on the evolution of SOM amount

De Vos, B., M. Van Meirvenne, P. Quataert, J. Deckers, and B. Muys. 2005.

and composition in plots harvested 15+ yr before sampling is needed

Predictive quality of pedotransfer functions for estimating bulk density of forest soils. Soil Sci. Soc. Am. J. 69:500–510. doi:10.2136/sssaj2005.0500

to ascertain long-term ef ects of forest harvesting in these soils.

Diochon, A.C., and L. Kellman. 2009. Physical fractionation of soil organic matter: Destabilization of deep soil carbon following harvesting of a

ACKNOWLEDGMENTS

temperate coniferous forest. J. Geophys. Res.-. Biogeosci. 114:G01016. h is study was funded through a Natural Sciences and Engineering

doi:10.1029/2008JG000844.

Research Council of Canada (NSERC) Discovery Grant. We thank Dr. Dyck, W.J., and D.W. Cole. 1994. Strategies for determining consequences of Robert Hudson for his guidance in the i eld and Dr. Hans Schreier for

harvesting and associated practices on long-term productivity. In: W.J. Dyck, comments which led to the improvement of this paper. We also thank D.W. Cole, and N.B. Comerford, editors, Impacts of forest harvesting on long-term site productivity. Chapman & Hall, London, UK. p. 13–40.

i eld assistants Marina Romeo and Peter Shanahan and laboratory Eberhardt, L.L., and J.M. h omas. 1991. Designing environmental i eld studies. manager Carol Dyck for her unwavering thoroughness. Finally, we are

Ecol. Monogr. 61:53–73. doi:10.2307/1942999 grateful for the work of three anonymous reviewers who provided very

Environment Canada. 2011. Canadian climate normals 1971–2000. Environment helpful comments on a previous version of this manuscript.

Canada, Fredericton, NB, Canada. http://climate.weatheroi ce.gc.ca/ climate_normals/index_e.html (accessed 7 Mar. 2011).

REFERENCES

Eusterhues, K., C. Rumpel, M. Kleber, and I. Kögel-Knabner. 2003. Stabilisation Aber, J.D., D.B. Botkin, and J.M. Melillo. 1979. Predicting the ef ects of dif erent

of soil organic matter by interactions with minerals as revealed by mineral harvesting regimes on productivity and yield in northern hardwoods. Can.

dissolution and oxidative degradation. Org. Geochem. 34:1591–1600. J. For. Res. 9:10–14 doi:10.1139/x79-002

doi:10.1016/j.orggeochem.2003.08.007

Baldock, J.A., and J.O. Skjemstad. 2000. Role of the soil matrix and minerals Eusterhues, K., C. Rumpel, and I. Kögel-Knabner. 2005. Organo-mineral in protecting natural organic materials against biological attack. Org.

associations in sandy acid forest soils: Importance of specii c surface area, Geochem. 31:697–710 doi:10.1016/S0146-6380(00)00049-8

iron oxides and micropores. Eur. J. Soil Sci. 56:753–763 10.1111/j.1365- Bascomb, C.L. 1968. Distribution of pyrophosphate-extractable iron and

2389.2005.00710.x.

organic carbon in soils of various groups. Eur. J. Soil Sci. 19:251–268. Federer, C.A. 1984. Organic-matter and nitrogen-content of the forest doi:10.1111/j.1365-2389.1968.tb01538.x

l oor in even-aged northern hardwoods. Can. J. For. Res. 14:763–767. Bekele, A., L. Kellman, and H. Beltrami. 2007. Soil proi le CO2 concentrations

doi:10.1139/x84-136

in forested and clear cut sites in Nova Scotia, Canada. For. Ecol. Manage. Federer, C.A., and J.W. Hornbeck. 1985. h e buf er capacity of forest soils in new 242:587–597. doi:10.1016/j.foreco.2007.01.088

England. Water Air Soil Pollut. 26:163–173. doi:10.1007/BF00292066 Bengtsson, J., and F. Wikstrom. 1993. Ef ects of whole-tree harvesting on the

Federer, C.A., D.E. Turcotte, and C.T. Smith. 1993. h e organic fraction-bulk amount of soil carbon: Model results. N. Z. J. For. Sci. 23:380–389.

density relationship and the expression of nutrient content in forest soils. Borchers, J.G., and D.A. Perry. 1992. h e inl uence of soil texture and aggregation

Can. J. For. Res. 23:1026–1032. doi:10.1139/x93-131 on carbon and nitrogen dynamics in Southwest Oregon forests and

Fontaine, S., S. Barot, P. Barre, N. Bdioui, B. Mary, and C. Rumpel. 2007. Stability clearcuts. Can. J. For. Res. 22:298–305. doi:10.1139/x92-039

of organic carbon in deep soil layers controlled by fresh carbon supply. Boucneau, G., M. Van Meirvenne, and G. Hofman. 1998. Comparing

Nature (London) 450:277–280 10.1038/nature06275. doi:10.1038/ pedotransfer functions to estimate soil bulk density in northern Belgium.

nature06275

Pedologie-h emata 5:67–70. Gabriel, C.E., and L. Kellman. 2011. Examining moisture and temperature Box, G.E.P., and D.R. Cox. 1964. An analysis of transformations. J. R. Stat. Soc.,

sensitivity of soil organic matter decomposition in a temperate coniferous B 26:211–252.

forest soil. Biogeosciences Discuss. 8:1369–1409. doi:10.5194/bgd-8- Bradley, R.L., W.L. Martin, and J.P. Kimmins. 2001. Post-clearcutting

1369-2011

chronosequence in the B.C. Coastal Western Hemlock Zone- IV. Gartzia-Bengoetxea, N., A. González-Arias, A. Merino, and I. Martínez de Modeling forest l oor N dynamics and the possible role of denitrii cation.

Arano. 2009. Soil organic matter in soil physical fractions in adjacent J. Sust. For. 14:69–91 10.1300/J091v14n01_04.

semi-natural and cultivated stands in temperate Atlantic forests. Soil Biol. Buurman, P., F. Peterse, and G. Almendros Martin. 2007. Soil organic matter

Biochem. 41:1674–1683. doi:10.1016/j.soilbio.2009.05.010 chemistry in allophanic soils: A pyrolysis-GC/MS study of a Costa Rican

Gholz, H.L., and R.F. Fisher. 1982. Organic matter production and distribution Andosol catena. Eur. J. Soil Sci. 58:1330–1347. doi:10.1111/j.1365-

in slash pine (Pinus Elliottii) plantations. Ecology 63:1827–1839. 2389.2007.00925.x

doi:10.2307/1940124

Buurman, P., and L.P. Van Reeuwijk. 1984. Proto-imogolite and the Grand, S., and L.M. Lavkulich. 2011. Depth distribution and predictors of soil process of Podzol formation-A critical note. J. Soil Sci. 35:447–452.

organic carbon in Podzols of a forested watershed in southwestern Canada. doi:10.1111/j.1365-2389.1984.tb00301.x

Soil Sci. 176:164–174. doi:10.1097/SS.0b013e3182128671 Chaer, G.M., D.D. Myrold, and P.J. Bottomley. 2009. A soil quality index based

Grand, S., and L.M. Lavkulich. 2008. Reactive soil components and pedogenesis on the equilibrium between soil organic matter and biochemical properties

of highly productive coastal podzols. Geochim.Cosmochim.Acta, 72(12), of undisturbed coniferous forest soils of the Pacii c Northwest. Soil Biol.

Goldschmidt Abstracts Suppl. A323. Pergamon, Oxford. Biochem. 41:822–830. doi:10.1016/j.soilbio.2009.02.005

Gregorich, E.G., M.H. Beare, U.F. McKim, and J.O. Skjemstad. 2006. Chemical Covington, W.W. 1981. Changes in forest l oor organic matter and nutrient

and biological characteristics of physically uncomplexed organic matter. content following clear cutting in northern hardwoods. Ecology 62:41–

Soil Sci. Soc. Am. J. 70:975–985. doi:10.2136/sssaj2005.0116 48. doi:10.2307/1936666

Gulde, S., H. Chung, W. Amelung, C. Chang, and J. Six. 2008. Soil carbon Crow, S.E., K. Lajtha, R.D. Bowden, Y. Yano, J.B. Brant, B.A. Caldwell, and

saturation controls labile and stable carbon pool dynamics. Soil Sci. Soc.

www.soils.org/publications/sssaj

Am. J. 72:605–612. doi:10.2136/sssaj2007.0251 Luxembourg beech and hornbeam forests. For. Ecol. Manage. 257:1732– Gundersen, P., I. Callesen, and W. de Vries. 1998. Nitrate leaching in forest

1739. doi:10.1016/j.foreco.2009.01.030

ecosystems is related to forest l oor C/N ratios. Environ. Pollut. 102:403– Kurz, W.A., M. Apps, E. Bani eld, and G. Stinson. 2002. Forest carbon accounting 407. doi:10.1016/S0269-7491(98)80060-2

at the operational scale. For. Chron. 78:672–679 10.5558/tfc78672–5. Gundersen, P., and L. Rasmussen. 1990. Nitrii cation in forest soils: Ef ects

Lee, J., I.K. Morrison, J. Leblanc, M.T. Dumas, and D.A. Cameron. 2002. Carbon from nitrogen deposition on soil acidii cation and aluminum release. Rev.

sequestration in trees and regrowth vegetation as af ected by clearcut and Environ. Contam. Toxicol. 113:1–45. doi:10.1007/978-1-4612-3366-4_1

partial cut harvesting in a second-growth boreal mixedwood. For. Ecol. Hannam, K.D., S.A. Quideau, B.E. Kishchuk, S.W. Oh, and R.E. Wasylishen.

Manage. 169:83–101. doi:10.1016/S0378-1127(02)00300-6 2005. Forest-l oor chemical properties are altered by clear-cutting in boreal

Littell, R.C., G.A. Milliken, W.W. Stroup, R.D. Woli nger, and O. Schabenberger. mixedwood forest stands dominated by trembling aspen and white spruce.

2006. SAS for mixed models. SAS Inst., Cary, NC. Can. J. For. Res. 35:2457–2468. doi:10.1139/x05-140

Londo, A.J., M.G. Messina, and S.H. Schoenholtz. 1999. Forest harvesting Harrison, R.B., P.W. Footen, and B.D. Strahm. 2011. Deep soil horizons:

ef ects on soil temperature, moisture, and respiration in a bottomland Contribution and importance to soil carbon pools and in assessing whole-

hardwood forest. Soil Sci. Soc. Am. J. 63:637–644. doi:10.2136/ ecosystem response to management and global change. For. Sci. 57:67–76.

sssaj1999.03615995006300030029x

Haslett, J., and S.J. Haslett. 2007. h e three basic types of residuals for a linear Lundström, U.S., N. van Breemen, and D. Bain. 2000. h e podzolization process. model. Int. Statist. Rev. 75:1–24. doi:10.1111/j.1751-5823.2006.00001.x

A review. Geoderma 94:91–107. doi:10.1016/S0016-7061(99)00036-1 Hazlett, P.W., A.M. Gordon, R.P. Voroney, and P.K. Sibley. 2007. Impact of

McGroddy, M.E., T. Daufresne, and L.O. Hedin. 2004. Scaling of C:N:P harvesting and logging slash on nitrogen and carbon dynamics in soils

stochiometry in forests worldwide: Implications of terrestrial Redi ed-type from upland spruce forests in northeastern Ontario. Soil Biol. Biochem.

ratios. Ecology 85:2390–2401. doi:10.1890/03-0351 39:43–57. doi:10.1016/j.soilbio.2006.06.008

McLean, E.O. 1965. Aluminum. In: C.A. Black, editor, Methods of soil analysis, Hendrickson, O.Q., L. Chatarpaul, and D. Burgess. 1989. Nutrient cycling

part II. ASA, Madison, WI. p. 992–994.

following whole-tree and conventional harvest in northern mixed forest. Mikutta, R., M. Kleber, and R. Jahn. 2005. Poorly crystalline minerals protect Can. J. For. Res. 19:725–735. doi:10.1139/x89-112

organic carbon in clay subfractions from acid subsoil horizons. Geoderma Heuscher, S.A., C.C. Brandt, and P.M. Jardine. 2005. Using soil physical and

128:106–115. doi:10.1016/j.geoderma.2004.12.018 chemical properties to estimate bulk density. Soil Sci. Soc. Am. J. 69:51–

Mikutta, R., M. Kleber, M. Torn, and R. Jahn. 2006. Stabilization of soil 56. doi:10.2136/sssaj2005.0051.

organic matter: Association with minerals or chemical recalcitrance? Holmes, K.W., A. Wherrett, A. Keating, and D.V. Murphy. 2012. Meeting bulk

Biogeochemistry 77:25–56. doi:10.1007/s10533-005-0712-6 density sampling requirements ei ciently to estimate soil carbon stocks.

Miralles, I., R. Ortega, G. Almendros, M. Sánchez-Marañón, and M. Soriano. 2009. Aust. J. Soil Res. 49:680–695. doi:10.1071/SR11161.

Soil quality and organic carbon ratios in mountain agroecosystems of South- Jiang, H., M.J. Apps, C. Peng, Y. Zhang, and J. Liu. 2002. Modeling the inl uence

east Spain. Geoderma 150:120–128. doi:10.1016/j.geoderma.2009.01.011 of harvesting on Chinese boreal forest carbon dynamics. For. Ecol. Manage.

Moran, K.K., J. Six, W.R. Horwath, and C. van Kessel. 2005. Role of mineral- 169:65–82. doi:10.1016/S0378-1127(02)00299-2

nitrogen in residue decomposition and stable soil organic matter formation. John, B., T. Yamashita, B. Ludwig, and H. Flessa. 2005. Storage of organic carbon

Soil Sci. Soc. Am. J. 69:1730–1736. doi:10.2136/sssaj2004.0301 in aggregate and density fractions of silty soils under dif erent types of land

Morris, D.M. 2009. Changes in DOC and DON l uxes in response to harvest use. Geoderma 128:63–79. doi:10.1016/j.geoderma.2004.12.013

intensity of black-spruce dominated forest ecosystems in northwestern Johnson, C.E. 1995. Soil-nitrogen status 8 years at er whole-tree clear-cutting.

Ontario. Can. J. Soil Sci. 89:67–79. doi:10.4141/CJSS07027 Can. J. For. Res. 25:1346–1355. doi:10.1139/x95-147

Nalder, I.A., and H.G. Merriam. 1995. Simulating carbon dynamics of the boreal Johnson, C.E., R.B. Romanowicz, and T.G. Siccama. 1997. Conservation of

forest in Pukaskwa National Park. Water Air Soil Pollut. 82:283–298. exchangeable cations at er clear-cutting of a northern hardwood forest.

doi:10.1007/BF01182841

Can. J. For. Res. 27:859–868 10.1139/x96-192. Nave, L.E., E.D. Vance, C.W. Swanston, and P.S. Curtis. 2010. Harvest impacts Johnson, D.W. 1992. Ef ects of forest management on soil carbon storage. Water

on soil carbon storage in temperate forests. For. Ecol. Manage. 259:857– Air Soil Pollut. 64:83–120. doi:10.1007/BF00477097

866. doi:10.1016/j.foreco.2009.12.009

Johnson, D.W., and P.S. Curtis. 2001. Ef ects of forest management on soil C and Nierop, K.G.J., and J.M. Verstraten. 2003. Organic matter formation in sandy N storage: Meta analysis. For. Ecol. Manage. 140:227–238. doi:10.1016/

subsurface horizons of Dutch coastal dunes in relation to soil acidii cation. S0378-1127(00)00282-6

Org. Geochem. 34:499–513. doi:10.1016/S0146-6380(02)00249-8 Johnson, D.W., J.D. Murphy, B.M. Rau, and W.W. Miller. 2011. Subsurface

Niinistö, S.M., S. Kellomäki, and J. Silvola. 2011. Seasonality in a boreal forest carbon contents: Some case studies in forest soils. For. Sci. 57:3–10.

ecosystem af ects the use of soil temperature and moisture as predictors of soil Johnson, J.E., D.W. Smith, and J.A. Burger. 1985. Ef ects on the forest l oor

CO2 el ux. Biogeosciences 8:3169–3186. doi:10.5194/bg-8-3169-2011 of whole-tree harvesting in an Appalachian oak forest. Am. Midl. Nat.

Norris, C.E., S.A. Quideau, J.S. Bhatti, and R.E. Wasylishen. 2011. Soil carbon 114:51–61. doi:10.2307/2425240

stabilization in jack pine stands along the Boreal Forest Transect Case Study. Johnson, K., F.N. Scatena, and Y. Pan. 2010. Short- and long-term responses of

Glob. Change Biol. 17:480–494. doi:10.1111/j.1365-2486.2010.02236.x total soil organic carbon to harvesting in a northern hardwood forest. For.

Oades, J. 1988. h e retention of organic matter in soils. Biogeochemistry 5:35– Ecol. Manage. 259:1262–1267. doi:10.1016/j.foreco.2009.06.049

70. doi:10.1007/BF02180317

Kalbitz, K., B. Glaser, and R. Bol. 2004. Clear-cutting of a Norway spruce stand: Pari tt, R.L. 2009. Allophane and imogolite: Role in soil biogeochemical Implications for controls on the dynamics of dissolved organic matter

processes. Clay Miner. 44:135–155. doi:10.1180/claymin.2009.044.1.135 in the forest l oor. Eur. J. Soil Sci. 55:401–413. doi:10.1111/j.1351-

Parker, J.L., I.J. Fernandez, L.E. Rustad, and S.A. Norton. 2002. Soil organic 0754.2004.00609.x

matter fractions in experimental forested watersheds. Water Air Soil Kalra, Y.P., and D.G. Maynard. 1991. Methods manual for forest soil and plant

Pollut. 138:101–121. doi:10.1023/A:1015516607941 analysis. Forestry Canada, Northwest Region, Northern Forestry Centre,

Paul, E. 1984. Dynamics of organic matter in soils. Plant Soil 76:275–285. Edmonton, AB.

doi:10.1007/BF02205586

Keeney, D.R. 1980. Prediction of soil nitrogen availability in forest ecosystems: Pennock, D.J., and C. van Kessel. 1997. Clear-cut forest harvest impacts on soil A literature review. For. Sci. 26:159–171.

quality indicators in the mixedwood forest of Saskatchewan, Canada. Kettler, T.A., J.W. Doran, and T.L. Gilbert. 2001. Simplii ed method for soil

Geoderma 75:13–32. doi:10.1016/S0016-7061(96)00075-4 particle-size determination to accompany soil-quality analyses. Soil Sci.

Petersen, L. 1976. Podzols and podzolization. DSR Forlag, Copenhagen, Denmark. Soc. Am. J. 65:849–852. doi:10.2136/sssaj2001.653849x

Prescott, C.E., L.L. Blevins, and C.L. Staley. 2000. Ef ects of clear-cutting on Kleber, M., R. Mikutta, M.S. Torn, and R. Jahn. 2005. Poorly crystalline mineral

decomposition rates of litter and forest l oor in forests of British Columbia. phases protect organic matter in acid subsoil horizons. Eur. J. Soil Sci.

Can. J. For. Res. 30:1751–1757. doi:10.1139/x00-102 56:717–725. 10.1111/j.1365-2389.2005.00706.x.

Rasmussen, C., R.J. Southard, and W.R. Horwath. 2006. Mineral control of Kooijman, A.M., and G.B. Martinez-Hernandez. 2009. Ef ects of litter quality

organic carbon mineralization in a range of temperate conifer forest soils. and parent material on organic matter characteristics and N-dynamics in

Glob. Change Biol. 12:834–847. doi:10.1111/j.1365-2486.2006.01132.x

Soil Science Society of America Journal

Rasmussen, C., M.S. Torn, and R.J. Southard. 2005. Mineral assemblage and changes in a spruce ecosystem 25 years at er disturbance. Soil Sci. Soc. Am. aggregates control carbon dynamics in a California conifer forest. Soil Sci.

J. 70:2130–2145. doi:10.2136/sssaj2005.0027 Soc. Am. J. 69:1711–1721. doi:10.2136/sssaj2005.0040

Strahm, B.D., R.B. Harrison, T.A. Terry, T.B. Harrington, A.B. Adams, and P.W. Rasse, D.P., J. Mulder, C. Moni, and C. Chenu. 2006. Carbon turnover kinetics

Footen. 2009. Changes in dissolved organic matter with depth suggest the with depth in a French loamy soil. Soil Sci. Soc. Am. J. 70:2097–2105.

potential for postharvest organic matter retention to increase subsurface doi:10.2136/sssaj2006.0056

soil carbon pools. For. Ecol. Manage. 258:2347–2352. doi:10.1016/j. Rubino, M., J.A.J. Dungait, R.P. Evershed, T. Bertolini, P. De Angelis, A.

foreco.2009.03.014

D’Onofrio, A. Lagomarsino, C. Lubritto, A. Merola, F. Terrasi, and M.F. Tiessen, H., and J.W.B. Stewart. 1983. Particle-size fractions and their use Cotrufo. 2010. Carbon input belowground is the major C l ux contributing

in studies of soil organic matter. 2. Cultivation ef ects on organic- to leaf litter mass loss: Evidences from a 13C labelled-leaf litter experiment.

matter composition in size fractions. Soil Sci. Soc. Am. J. 47:509–514. Soil Biol. Biochem. 42:1009–1016. doi:10.1016/j.soilbio.2010.02.018

doi:10.2136/sssaj1983.03615995004700030023x Rumpel, C., and I. Kögel-Knabner. 2011. Deep soil organic matter—A key but

Ussiri, D.A.N., and C.E. Johnson. 2003. Characterization of organic matter in a poorly understood component of terrestrial C cycle. Plant Soil 338:143–

northern hardwood forest soil by 13C NMR spectroscopy and chemical 158. doi:10.1007/s11104-010-0391-5

methods. Geoderma 111:123–149. doi:10.1016/S0016-7061(02)00257-4 SAS Institute. 2008. SAS. Ver. 9.2. SAS Inst., Cary, NC.

Van Lierop, W. 1990. Soil pH and lime requirement determination. In: R.L. Scheel, T., C. Dorl er, and K. Kalbitz. 2007. Precipitation of dissolved organic

Westerman, editor, Soil testing and plant analysis. 3rd ed. SSSA, Madison, matter by aluminum stabilizes carbon in acidic forest soils. Soil Sci. Soc.

WI. p. 73–92.

Am. J. 71:64–74 10.2136/sssaj2006.0111. von Lützow, M., I. Kögel-Knabner, K. Ekschmitt, H. Flessa, G. Guggenberger, E. Schmidt, M.W.I., H. Knicker, and I. Kögel-Knabner. 2000. Organic matter

Matzner, and B. Marschner. 2007. SOM fractionation methods: Relevance accumulating in Aeh and Bh horizons of a Podzol— Chemical

to functional pools and to stabilization mechanisms. Soil Biol. Biochem. characterization in primary organo-mineral associations. Org. Geochem.

39:2183–2207. doi:10.1016/j.soilbio.2007.03.007 31:727–734. doi:10.1016/S0146-6380(00)00045-0

Waksman, S.A. 1924. Inl uence of microorganisms upon the carbon- Schoi eld, R.K., and A.W. Taylor. 1955. h e measurement of soil pH. Soil Sci. Soc.

nitrogen ratio in the soil. J. Agric. Sci. 14:555–562. doi:10.1017/ Am. Proc. 19:164–167. doi:10.2136/sssaj1955.03615995001900020013x

S0021859600003981

Simonson, R.W. 1959. Outline of a generalized theory of soil genesis. Soil Sci. Soc. Webster, R. 2007. Analysis of variance, inference, multiple comparisons and Am. Proc. 23:152–156. doi:10.2136/sssaj1959.03615995002300020021x

sampling ef ects in soil research. Eur. J. Soil Sci. 58:74–82. doi:10.1111/ Six, J., R.T. Conant, E.A. Paul, and K. Paustian. 2002. Stabilization mechanisms

j.1365-2389.2006.00801.x

of soil organic matter: Implications for C-saturation of soils. Plant Soil Yanai, R.D., W.S. Currie, and C.L. Goodale. 2003. Soil carbon dynamics at er 241:155–176. doi:10.1023/A:1016125726789

forest harvest: An ecosystem paradigm reconsidered. Ecosystems 6:197– Snyder, K.E., and R.D. Harter. 1985. Changes in solum chemistry following

212. doi:10.1007/s10021-002-0206-5

clearcutting of northern hardwood stands. Soil Sci. Soc. Am. J. 49:223– Zabowski, D., N. Whitney, J. Gurung, and J. Hatten. 2011. Total soil carbon in 228. doi:10.2136/sssaj1985.03615995004900010045x

the coarse fraction and at depth. For. Sci. 57:11–18. Soil Survey Staf . 2006. Keys to soil taxonomy. USDA-Natural Resources

Zinn, Y.L., R. Lal, J.M. Bigham, and D.V.S. Resck. 2007. Edaphic controls on soil Conserv. Serv., Washington, DC.

organic carbon retention in the Brazilian Cerrado: Texture and mineralogy. Sollins, P., P. Homann, and B.A. Caldwell. 1996. Stabilization and destabilization

Soil Sci. Soc. Am. J. 71:1204–1214. doi:10.2136/sssaj2006.0014 of soil organic matter: Mechanisms and controls. Geoderma 74:65–105.

Zummo, L.M., and A.J. Friedland. 2011. Soil carbon release along a gradient of doi:10.1016/S0016-7061(96)00036-5

physical disturbance in a harvested northern hardwood forest. For. Ecol. Spielvogel, S., J. Prietzel, and I. Kögel-Knabner. 2006. Soil organic matter

Manage. 261:1016–1026. doi:10.1016/j.foreco.2010.12.022

www.soils.org/publications/sssaj

1827