Uth Stte University DigitlCommons@USU Aspen Biliogrphy Aspen Reserch 2011 Ten-yer results from the long-term soil productivity study in spen ecosystems of the northern Gret Lkes region Richrd Voldseth Brin Plik John Elioff Follow this nd dditionl works t: https://digitlcommons.usu.edu/spen_i Prt of the Forest Sciences Commons Recommended Cittion Voldseth, R.; Plik, B.; Elioff, J. 2011. Ten-yer results from the long-term soil productivity study in spen ecosystems of the northern Gret Lkes region. USDA-FS Northern Reserch Sttion, Reserch Pper NRS-17 This Document is rought to you for free nd open ccess y the Aspen Reserch t DigitlCommons@USU. It hs een ccepted for inclusion in Aspen Biliogrphy y n uthorized dministrtor of DigitlCommons@USU. For more informtion, plese contct dyln.urns@usu.edu.
United Sttes Deprtment of Agriculture Forest Service Northern Reserch Sttion Reserch Pper NRS-17 Ten-yer Results from the Long-term Soil Productivity Study in Aspen Ecosystems of the Northern Gret Lkes Region Richrd Voldseth Brin Plik John Elioff
Astrct Impcts of orgnic mtter removl nd compction on soil physicl nd chemicl properties nd forest productivity re reported from the fi rst 10 yers of the Long-Term Soil Productivity Study in Gret Lkes spen ecosystems. Orgnic mtter removl tretments included min ole, totl tree hrvest, nd totl tree hrvest with forest fl oor removl. Compction tretments included no compction eyond norml levels from hrvest, moderte compction, nd hevy compction. Min ole hrvest with no dditionl compction served s the control ginst which other tretments were compred. Study tretments were replicted in three loctions on cly lom, silt lom, nd lomy snd soil. All compction tretments on ll three soil types incresed ulk density ove prehrvest levels. In most cses, ulk density t yer 10 hd decresed signifi cntly compred to yer 0, ut ws still generlly ove prehrvest levels. Totl cron nd nitrogen showed no impct from tretment t yer 10. In generl, soil ctions were little ffected y orgnic mtter removl. The mjor exceptions were lower ner-surfce clcium in the lomy snd soil with totl tree hrvest plus forest fl oor removl, nd lower potssium t cm depth in the lom soil for oth totl tree hrvest with nd without forest fl oor removl. Compction nd orgnic mtter removl tretments impcted oveground forest productivity, however the effects were not universl cross the soil types. Aoveground iomss production declined on the lom soil with moderte nd hevy compction. Production incresed with moderte compction on the lomy snd nd cly lom soils, ut signifi cntly decresed with hevy compction on the cly lom soil. Totl tree hrvest with forest fl oor removl reduced production on the lomy snd nd lom soils, while it incresed production on the cly lom soil. Results from this study suggest tht hevy compction nd/or high orgnic mtter removls (e.g., totl tree hrvest plus forest fl oor removl) re generlly detrimentl to sustining forest productivity cross soil types. Totl tree hrvest with limited compction my e sustinle, t lest s refl ected in 10 yer results, fter one hrvest entry. Mngers should e cutious of pproches involving whole-tree hrvests, or even ole-only hrvests, on short rottions (~10 yers), s such pproches will limit the potentil for recovery to prehrvest ulk densities nd my hve the potentil to increse compction to levels seen with hevy compction. Mnuscript received for puliction Jnury 2011 Pulished y: For dditionl copies: USDA FOREST SERVICE USDA Forest Service 11 CAMPUS BLVD., SUITE 200 Pulictions Distriution NEWTOWN SQUARE, PA 19073-3294 359 Min Rod Delwre, OH 43015-8640 Septemer 2011 Fx: 740-368-0152 Visit our homepge t: http://www.nrs.fs.fed.us/
INTRODUCTION In the fce of incresed interest in utiliztion of wood fier for iofuels, sustining long-term site productivity is fundmentl issue confronting forest mngement (Hendrickson et l. 1989, Powers et l. 1990, Wlmsley et l. 2009). Site productivity, tht we here define s sustined cpcity to cpture cron nd produce plnt iomss, is ffected y environmentl drivers, such s climte. Within the limits of climte, the potentil net primry productivity of site is regulted y iotic, chemicl, nd physicl soil properties nd processes, which, in turn, cn e ltered y humn-cused disturnces (Powers et l. 2004). How soil disturnces ffect productivity of forests is still not well understood (Powers et l. 2005). Soil properties directly ffected y disturnce include porosity nd orgnic mtter content (Powers et l. 1990). Porosity nd orgnic mtter regulte fundmentl ecosystem processes through their influence on wter nd gs exchnge, physicl restrictions on rooting, microil ctivity, soil ggregte stility, nd resource vilility. Forest hrvesting cn reduce porosity through compction y mchinery trffic. Soil porosity reflects continuum of void sizes tht vry with the minerl nture nd degree of wethering of the prent mteril (Powers 1999). The mechnism y which soil compction impcts productivity is through the rekdown of surfce ggregtes cusing decresed mcropore volume nd incresed soil ulk density (Powers 1999, Pritchett nd Fisher 1987). This cn impede oth root growth nd wter infiltrtion, nd cn lter the lnce of oxygen nd cron dioxide in the soil profile nd gs exchnge with the tmosphere which, in turn, cn lter soil ph nd nutrient regimes (Bllrd 2000, Powers 1999). Soil orgnic mtter content is directly relted to the mount of orgnic mtter entering the soil from plnt tissue. Forest floor orgnic mtter constitutes n energy source for soil fun nd microes nd is reservoir of nutrients supplied to the soil through pulses in litterfll nd root sloughge. Direct removl of plnt nd plnt-derived orgnic mtter, including the forest floor, s well s reduced cpcity to produce new orgnic mtter, cn led to reductions in soil orgnic mtter concentrtions. Moreover, the loss of forest floor cn result in incresed soil tempertures nd reduction of decomposition products tht id in the development of soil structurl ggregtes (Powers 1999). Soil orgnic mtter loss cn lso led to decreses in soil wter-holding cpcity nd cn lter soil ion exchnge nd nutrient cpitl (Powers 1999, Zowski et l. 1994). The Authors RICHARD VOLDSETH is reserch ssocite with the Deprtment of Soil Science, North Dkot Stte University, Frgo, ND. BRIAN PALIK is reserch ecologist with the Center for Reserch on Ecosystem Chnge, Northern Reserch Sttion, Grnd Rpids, MN. JOHN ELIOFF is forestry technicin (retired) with the Center for Reserch on Ecosystem Chnge, Northern Reserch Sttion, Grnd Rpids, MN. 1
The North Americn Long-Term Soil Productivity (LTSP) Study ws conceived to ddress the consequences of pulse soil disturnce on forest productivity, s impcted y reductions in soil porosity, through compction, nd soil orgnic mtter content, through orgnic mtter removl. The U.S. Deprtment of Agriculture - Forest Service is leglly ound y the Ntionl Forest Mngement Act of 1976 to mnge lnd in such wy tht its long-term productivity is not impired (Powers et l. 1990, Powers et l. 1990, Powers 1999, Powers et l. 2005, Powers 2006, Tirks et l. 1997). In response, the Forest Service hs chrged ech region with the Ntionl Forest System (NFS) with developing soil qulity monitoring stndrds tht cn detect losses in productive potentil of the lnd over rottion (Pge- Dumroese et l. 2000, Powers et l. 1990, Powers et l. 1990). In 1989, s result of these concerns nd mndtes, Forest Service reserch scientists nd NFS mngers set the foundtion for the LTSP progrm (Powers 2006, Tirks et l. 1997). Tody, the LTSP progrm is n interntionl endevor with identicl experimentl designs nd study questions eing ddressed t multiple sites. The LTSP experiment specificlly trgeted soil porosity nd orgnic mtter for mnipultion in lrge-scle, long-term experiments. The LTSP experiment ws designed to ddress the following primry question: do pulse reductions in site orgnic mtter nd/or soil porosity reduce the sustined productive potentil of site? Tretments include three levels of soil compction fctored with three levels of oveground orgnic mtter removl. The rnges of tretments were chosen to encompss the rnge of possiilities occurring under contemporry mngement. The Lke Sttes instlltions of the LTSP Study re locted in forests dominted y tremling nd igtooth spen (Populus tremuloides Michx., Populus grndidentt Michx.). These forests re the dominnt erly successionl forest type in the region (Schulte et l. 2007) nd s such re of tremendous economic nd ecologicl importnce. Tremling spen dominted forests re erly successionl cross rnge of site nd soil conditions nd develop with reltively uniform tree sizes with culmintion of men nnul increment occurring round 30 to 40 yers of ge. They lend themselves to intense mechnized hrvesting regimes nd whole (totl) tree utiliztion (Aln 1991) for wood products nd, more recently, feedstocks for wood-sed iofuels. The long-term productivity impcts of intensive hrvesting nd iomss removl for energy feedstocks re not well understood (Grigl 2000). Monitoring of the LTSP Study is to e conducted over one full rottion or out 50 yers. This report presents findings from the first 10 yers of monitoring in the Lke Sttes LTSP instlltions. Severl tenth-yer syntheses from the ntionl effort hve een pulished previously (Powers et l. 2004, 2005). Mirroring the ntionl progrm, our primry ojective for this project is to understnd how orgnic mtter removl nd chnges in soil porosity due to compction ffect site s productive crrying cpcity nd, ultimtely, sustinility of iomss production in spen ecosystems. We sked the following questions: Is there n effect of orgnic mtter removl or soil compction on soil physicl nd chemicl vriles tht my ccount for productivity responses? Is there n effect of orgnic mtter removl or compction tretments on vegettion productivity nd undnce fter 10 yers? At wht level of orgnic mtter removl or compction re effects evident? METHODS Study Ares This study is sed in three geogrphiclly seprte loctions, with ech site representing distinctly different soil texture. All sites were estlished in fully stocked evenged stnds of the spen (Populus tremuloides Michx. nd Populus grndidentt Michx.) (Stone 2001). The three sites were estlished in consecutive yers for ese in estlishment nd field smpling logistics. The first site, estlished in 1992, is on cly lom soil locted on the Ottw Ntionl Forest in the upper peninsul of Michign, USA (Fig. 1). Soils t this loction were clssified s Frigid Vertic Glossudlfs formed in lcustrine clys. This site occurs in the orel moist Holdridge life zone (Lugo et l. 1999), 2
Figure 1. LTSP core nd ffi lite sites reltive to the pproximte rnge of commercil forest in the United Sttes nd portions of Cnd (fter Powers et l. 2005). Open circles indicte sites tht hd t lest 10 yers of dt y 2005. The pproximte loctions of the Chippew, Ottw, nd Huron Ntionl Forest LTSP sites re indicted. t n pproximte elevtion of 350 m..s.l. Men nnul precipittion is out 77 cm. Stnd ge t time of estlishment ws 60 yers, with site index for spen t ge 50 yers estimted t 17 m (Stone 2001). Trees were hrvested in lte Jnury nd erly Ferury 1992. Snow depth verged pproximtely 80 cm over unfrozen soils (Stone 2001). The second site, estlished in 1993, is on silt lom soil locted on the Chippew Ntionl Forest in northern Minnesot, USA (Fig. 1). Soils were clssified s Frigid Hplic Glossudlfs formed in loess nd till. This site occurs in the orel moist Holdridge life zone t n pproximte elevtion of 410 m..s.l. Men nnul precipittion is out 64 cm. Stnd ge t time of study estlishment ws 70 yers, with site index for spen t ge 50 yers estimted t 23 m (Stone 2001). Trees were hrvested in Jnury nd Ferury 1993. Averge snow depth incresed over the period of hrvest from pproximtely 30 cm to 46 cm over discontinuously frozen soils; frost rnged in depth from 5 to 10 cm y end of hrvest (Stone 2001). 3
The third site, estlished in 1994, is on lomy snd soil on the Huron Ntionl Forest in estern Michign, USA (Fig. 1). Soils were clssified s Frigid Typic Udipsmments nd Frigid Entic Hplorthods formed in outwsh snds. This site occurs in the cool temperte moist Holdridge life zone t n pproximte elevtion of 240 m..s.l. Men nnul precipittion is out 75 cm. Stnd ge t time of estlishment ws 35 yers, with site index for spen t ge 50 yers estimted t 19 m (Stone 2001). Trees were hrvested in lte Jnury 1994. Averge snow depth ws pproximtely 37 cm over frozen soils; depth of frost verged nerly 22 cm (Stone 2001). Experimentl Design This reserch is sed on conceptul model (Fig. 2) developed y the Ntionl LTSP Progrm (Powers et l. 1990, Powers et l. 2005) nd pplied to the northern Gret Lkes spen ecosystem study. The experimentl design includes three fctors (compction, orgnic mtter removl, yer), with tretments rrnged in rndomized complete lock (replictes). There were three levels of soil compction (C) nd three levels of orgnic mtter removl (OM), for totl of nine core tretments (Tle 1). The levels of compction were: C 0, no dditionl compction ove tht due to hrvesting; C 1, moderte compction; nd C 2, hevy compction. The levels of orgnic mtter removl were: OM 0, min ole only hrvest; OM 1, oveground totl tree hrvest; nd OM 2, oveground totl tree hrvest plus removl of forest floor. Figure 2. Conceptul model used to guide the LTSP experimentl design, indicting the overriding infl uence of soil porosity nd site orgnic mtter on fundmentl processes tht regulte primry productivity within climtic constrints (fter Powers et l. 1998, Powers et l. 2005). 4
Tle 1. Description of compction nd orgnic mtter removl tretments. Orgnic Mtter Removl Compction OM 0 OM 1 OM 2 C 0 Min ole hrvest, no dditionl compction (C 0, OM 0 ) Totl tree hrvest, no dditionl compction (C 0, OM 1 ) Totl tree hrvest + forest fl oor removl, no dditionl compction (C 0, OM 2 ) C 1 Min ole hrvest, moderte compction (C 1, OM 0 ) Totl tree hrvest, moderte compction (C 1, OM 1 ) Totl tree hrvest + forest fl oor removl, moderte compction (C 1, OM 2 ) C 2 Min ole hrvest, hevy compction (C 2, OM 0 ) Totl tree hrvest, hevy compction (C 2, OM 1 ) Totl tree hrvest + forest fl oor removl, hevy compction (C 2, OM 2 ) Ech set of nine tretments ws replicted three times t ech geogrphic loction on 50 m x 50 m tretment plot. Plots were estlished prior to logging nd tretments were rndomly ssigned to the plots. After hrvesting, the forest floor on the OM 2 tretment ws removed y hnd rking down to the top of the minerl soil nd removing the mteril from the site prior to pplying compction tretments. Compction tretments were pplied during erly spring with one or more psses using Cterpillr trctor or frontend loder. Additionl detil on the study res nd the equipment used to pply tretments cn e found in Stone (2001). After tretment instlltion, ll plots regenerted nturlly to spen nd ssocited species, with the exception of the Chippew Ntionl Forest site. At this site, some new spen suckers were dmged from lte ppliction of compction tretments; in these plots, dditionl spen seedlings were plnted to offset ny potentil losses in initil low stocking. Field Mesurements Soil ws collected nd vegettion mesurements were mde prior to hrvest, prior to compction tretment (post-orgnic mtter removl), post-compction (i.e. post-tretment t end of the sme growing seson in which compction ws pplied or yer 0), in yer 1, yer 5, nd yer 10. Yer 5 results re not presented in this report s erlier results hve een reported elsewhere (Stone 2001, 2002). All smpling nd mesurements were conducted within the interior 40 m x 40 m of ech plot, llowing 5-m uffer round the trget smple re. Initilly, five smple points were estlished systemticlly nd uniformly within ech tretment plot. In yer 5, the numer of points ws expnded to eight, nd in yer 10 to nine points. Soil In ech mesurement yer, rndom zimuth nd distnce (rnge of 1 to 3 m) from smple point center ws determined nd used to locte smpling re for soil. New smpling loctions were constrined to e t lest 1 m from the previous smple loction. Soil smples were collected using 30 cm deep y 6.35 cm dimeter (190.5 cm 3 ) stinless steel core fitted with plstic tue. Tues were removed nd tken to the l for processing. Vegettion In ech tretment plot, oveground herceous vegettion ws collected t five smple points in 1-m 2 clip plots during lte July to erly August. Clip plot loctions were determined similr to soil smples points, s descried ove. Woody shru nd tree vegettion ws smpled in mid-septemer to Octoer in 10-m 2 suplots centered on the smple points. All woody stems > 15 cm tll were mesured nd recorded y 2-mm dimeter clsses, with dimeters mesured t stem heights of 25 cm for individuls < 1.4 m tll nd t 1.4 m for individuls reching this height. 5
Smple Preprtion nd Dt Summriztion Plnt mteril from the clip plots ws oven dried t 60 C for 48 hours, nd weighed to determine dry weight iomss. Allometric equtions developed for this study (Perl nd Aln 1993) were used to estimte oveground iomss (Mg h -1 ) of ll woody species. Stem counts were used to determine densities of woody species (numer h -1 ). Estimtes of iomss nd densities were determined for spen lone, s well s the totl for ll woody vegettion comined. Soil cores were sectioned into cm, cm nd 20-30 cm depth segments. Minerl soil smples from these sections were sieved to the 2-mm frction to remove corse frgments nd root mteril. Smples were then oven-dried t 105 C until no further loss of moisture could e detected fter severl repeted weighings. The following soil mesures were determined from these smples: soil ulk density (D, g cm -3 ); totl soil cron storge (Mg h -1 ); totl soil nitrogen storge (Mg h -1 ); clcium (C, cmol kg -1 ); potsium (K, cmol kg -1 ); mgnesium (Mg, cmol kg -1 ); sodium (N, cmol kg -1 ); nd effective ction exchnge cpcity (CECe, cmol kg -1 ). Fine frction D ws determined s the mss of the < 2 mm dimeter mteril, from ech depth ctegory, divided y the volume occupied y tht mteril. Soil smples used in the D determintions were comined within tretment plot y depth ctegory, thoroughly mixed, nd susmpled for chemicl nlysis. Totl C nd N determintions were mde on Crlo Er Model NA 1500 series 2 nitrogen/cron/sulphur nlyzer (CE Elntech, Inc., Lkewood, NJ). Ctions were extrcted using Mehlich 3 solution with detection y inductively coupled plsm nlysis (Wolf nd Beegle 1995). Totl CECe ws determined y summing C, Mg, K, nd N (Ross 1995). Sttisticl Anlysis Ech loction in the study ws nlyzed seprtely due to lrge differences in climte nd soil type. At ech loction, suplot dt were verged to derive tretment plot mens for n=three replictes for tretment comintions, with the following exceptions: n error t the time of tretment instlltion t the Ottw site resulted in only one replicte for the hevy compction + min ole hrvest tretment (C 2 OM 0 ), two replictes for the moderte compction + min ole hrvest tretment (C 1 OM 0 ), nd five replictes for the moderte compction + totl oveground orgnic mtter removl tretment (C 1 OM 2 ). For the Ottw nlyses, the mixed procedure in SAS (see elow) ws used to ccount for the unlnced design (Littell et l. 1996). All response vriles were found to meet or nerly meet ssumptions of normlity. Covrince structures ville within SAS were evluted for ech dt set, with n utoregressive model determined s est fit (smllest vrince) for this mixed-model pproch. The utoregressive structure hs homogeneous vrinces nd correltions tht decline exponentilly with time. Repeted mesures nlyses were conducted on ech response vrile using the proc mixed procedure in SAS (SAS Institute Inc. 1999) with replictions considered s rndom effects. The mixed effects model used ws: Y jklm = μ Y + α j + β k + γ l + ρ m + (αβ) jk + (αγ) jl + (αρ) jm + (βγ) kl + (βρ) km + (γρ) lm + (αβγ) jkl + (αβρ) jkm + (αγρ) jlm + (βγρ) klm + Є jklm where Y jklm is the mesured response for the m th repliction of the l th yer for the k th orgnic mtter removl tretment nd the j th compction tretment, μ Y is the overll men of Y jklm, α j is the fixed effect due to j th compction tretment, β k is the fixed effect due to k th orgnic mtter removl tretment, γ l is the fixed effect due to l th yer, ρ m is the rndom effect or lock due to the m th repliction, (αβ) jk is the interction fixed effect due to the k th orgnic mtter removl tretment nd the j th compction tretment, 6
(αγ) jl is the interction fixed effect due to the l th yer for the j th compction tretment, (αρ) jm is the rndom effect due to the m th repliction for the j th compction tretment, (βγ) kl is the interction fixed effect due to the l th yer for the k th orgnic mtter removl tretment, (βρ) km is the rndom effect due to the m th repliction for the k th orgnic mtter removl tretment, (γρ) lm is the rndom effect due to the m th repliction for the l th yer, (αβγ) jkl is the interction fixed effect due to the l th yer for the k th orgnic mtter removl tretment nd the j th compction tretment, (αβρ) jkm is the rndom effect due to the m th repliction for the k th orgnic mtter removl tretment nd the j th compction tretment, (αγρ) jlm is the rndom effect due to the m th repliction of the l th yer for the j th compction tretment, (βγρ) klm is the rndom effect due to the m th repliction of the l th yer for the k th orgnic mtter removl tretment, Є jklm is the rndom error due to the m th repliction of the l th yer for the k th orgnic mtter removl tretment nd the j th compction tretment. Five-yer intervls were used for nlyses. The Stterthwite degrees of freedom pproximtion ws utilized in SAS, which cn produce non-integer denomintor degrees of freedom (Littell et l. 1996). Comprisons were conducted vi lest squres mens (LSM) to test for rejection of the null hypotheses tht no differences existed mong tretment mens. The differences of LSM were computed in SAS using the pdiff option. In the cse of the unlnced design t the Ottw site, the results of the LSM my not equl the verge of the dt ecuse LSM imposes the model structure on the clculted men nd these djusted mens gurntee n unised estimtion of tretment mens (Littell et l. 1996, Spilke 2005). Twenty-four response vriles were evluted for ech site, including ulk density (D), totl cron, nd totl nitrogen t three soil depths, CECe, C, K, Mg, N t two soil depths, oveground totl plnt iomss, spen iomss, herceous iomss, totl woody species stem density nd spen stem density. Sttisticl tests were considered significnt t p 0.05. Our nlyses produced lrge numer of comprisons mong tretments nd over time, however the focus of this report is primrily on tenth yer responses, with some comprisons to yer 0 vlues for selected vriles. By design, the no dditionl compction + min ole hrvest tretment (C 0 OM 0 ) served s the control for testing the effects of ll other tretments in this experiment (Powers 1999). Additionlly, some comprisons were mde with prehrvest dt. RESULTS Interctions etween Compction nd Orgnic Mtter Removl Very few sttisticlly significnt interctions etween soil compction nd orgnic mtter removl were detected for most vriles within the first decde since tretment. Of 75 possile two-wy interctions we exmined, only seven were significnt t p 0.05. This indictes tht for the most prt, responses to incresing compction or incresing removl of orgnic mtter were independent of the level of the other vrile. The mjority of significnt interctions were t the Chippew Ntionl Forest silt lom soil site: CECe t cm, C t cm, long with totl iomss, spen iomss, nd totl stem density. Also, interctions for totl stem density nd N t cm t Ottw Ntionl Forest cly lom soil site were significnt. Due to the miniml numer of sttisticlly significnt interctions, herefter we test for differences mong levels of one min effect (e.g., soil compction) t the control level of the second min effect (e.g., orgnic mtter removl). Soil Bulk Density Lomy Snd Soil Immeditely fter tretment, oth moderte (C 1 ) nd hevy (C 2 ) compction, pooled cross orgnic mtter removl tretments, on the lomy snd soil, resulted in significnt (p < 0.05) increses in ulk density compred to C 0 (no dditionl compction) except tht 7
no significnt difference ws detected etween C 0 nd C 1 t 20-30 cm (Fig. 3). Moreover, ulk density on ll tretments t ll depths ws elevted ove the men prehrvest vlues (Fig. 3). For comprison, when compction tretments were compred within just OM 0 (min ole only tretment), ulk density for oth C 1 nd C 2 were still significntly greter thn C 0 t ll depths, lthough C 1 nd C 2 did not differ significntly from ech other (dt not shown). For ll compction tretments, ulk density t cm hd significntly decresed y yer 10, compred to yer 0, nd ulk density for C 1 nd C 2 were no longer significntly higher thn C 0 (Fig. 4). At the two deeper depths, ulk density vlues t yer 10 remined significntly greter (p < 0.05) thn the control (C 0 ) for moderte compction (C 1 ) t cm, nd hevy compction (C 2 ) t nd 20-30 cm. Also, t yer 10, ulk density of ll tretments t ll depths remined higher thn the men prehrvest vlues. Silt Lom Soil Immeditely fter tretment, oth moderte (C 1 ) nd hevy (C 2 ) compction tretments, pooled cross ll orgnic mtter removl tretments, resulted in significntly greter (p < 0.05) ulk density compred to C 0, ut only t cm (Fig. 5). However, ulk densities on ll tretments t ll depths were elevted ove the men prehrvest vlues (Fig. 5). For comprison, when compction tretments were compred within just OM 0, ulk density for oth C 1 nd C 2 were no longer significntly different from C 0 t the cm soil depth (dt not shown). Only hevy compction (C 2 ) t cm hd significnt decrese in ulk density y yer 10, compred to yer 0 (Fig. 6). At the two deeper depths, there were no tretment differences (p > 0.05) in ulk density t yer 10. However, t yer 10, ulk density of ll tretments t ll depths remined sustntilly higher thn the men prehrvest vlues. Bulk Density (g cm -3 ) 2 1.5 1 0.5 C0 C1 C 2 c c Bulk Density (g cm -3 ) 2 1.5 1 0.5 Yer 0 Yer 10 d c 0 cm cm 20-30 cm 0 C0 C1 C2 Compction Tretment y Soil Depth Compction Tretment Time Comprison Figure 3. Mens nd stndrd errors for ulk density immeditely following ppliction (yer 0) of C 1 (medium) nd C 2 (hevy) compction tretments, reltive to C 0 (no dditionl compction), for three soil depths on lomy snd soil t the Huron Ntionl Forest. Men vlues for ech compction tretment re pooled cross ll orgnic mtter removl tretments. Brs with common letters indicte mens were not signifi cntly different (p 0.05). Signifi cnce tests of compction tretments pply within ech soil depth ctegory only. Dshed horizontl lines re men prehrvest ulk density vlues, pooled cross ll tretments y depth. Figure 4. Mens nd stndrd errors for ulk density of compction tretments t cm immeditely fter tretment (yr 0) nd 10 yers fter tretment (yr 10) for the lomy snd soil t the Huron Ntionl Forest. Brs with common letters indicte mens re not signifi cntly different (p 0.05). Dshed horizontl line is the men prehrvest ulk density pooled cross ll tretment. Compction tretments re constrined to OM 0. 8
Bulk Density (g cm -3 ) 2 1.5 1 C0 C1 C 2 Bulk Density (g cm -3 ) 2 1.5 1 Yer 0 Yer 10 0.5 0.5 0 0 cm cm 20-30 cm C0 C1 C2 Compction Tretment y Soil Depth Compction Tretment Time Comprison Figure 5. Mens nd stndrd errors for ulk density immeditely following ppliction (yer 0) of C 1 (medium) nd C 2 (hevy) compction tretments, reltive to C 0 (no dditionl compction), for three soil depths on silt lom soil t the Chippew Ntionl Forest. Men vlues for ech compction tretment re pooled cross ll orgnic mtter removl tretments. Brs with common letters indicte mens were not signifi cntly different (p 0.05). Signifi cnce tests of compction tretments pply within ech soil depth ctegory only. Dshed horizontl lines re men prehrvest ulk density vlues, pooled cross ll tretments y depth. Figure 6. Mens nd stndrd errors for ulk density of compction tretments t cm immeditely fter tretment (yr 0) nd 10 yers fter tretment (yr 10) for silt lom soil t the Chippew Ntionl Forest. Brs with common letters indicte mens re not signifi cntly different (p 0.05). Dshed horizontl line is the men prehrvest ulk density pooled cross ll tretment. Compction tretments re constrined to OM 0. Cly Lom Soil Immeditely fter tretment, oth moderte (C 1 ) nd hevy (C 2 ) compction tretments, pooled cross ll orgnic mtter removl tretments, on the cly lom soil, resulted in significntly greter (p < 0.05) ulk density compred to C 0, t ll depths, except tht C 1 nd C 0 did not differ t 20-30 cm (Fig. 7). Bulk density of ll tretments ws sustntilly elevted ove the men prehrvest vlue only t cm (Fig. 7). Bulk density ws modertely elevted ove the prehrvest vlue t cm nd similr to the prehrvest vlue t 20-30 cm (Fig. 7). For comprison, when compction tretments were compred within just OM0, ulk densities were significntly different for most comprisons with C 0, except C 1 t cm nd C 2 t 20-30 cm (dt not shown). For ll tretments, ulk density in yer 10 ws not significntly different thn yer 0 t cm, ut ulk density ws significntly greter for C 2 compred to oth C 0 nd C 1 t yer 10 (Fig. 8). At the two deeper depths in yer 10, ulk density ws not significntly different thn the control (C 0 ) for either medium (C 1 ) or hevy compction (C 2 ) (dt not shown). At yer 10, ulk density of ll tretments t cm remined higher thn the men prehrvest vlues (Fig. 8), wheres ulk density t deeper depths ws very similr to prehrvest vlues (dt not shown). 9
2 C0 2 C1 Yer 0 Bulk Density (g cm -3 ) 1.5 1 C 2 c c Bulk Density (g cm -3 ) 1.5 1 Yer 10 0.5 0.5 0 0 cm cm 20-30 cm C0 C1 C2 Compction Tretment y Soil Depth Compction Tretment Time Comprison Figure 7. Mens nd stndrd errors for ulk density immeditely following ppliction (yr 0) of C 1 (medium) nd C 2 (hevy) compction tretments, reltive to C 0 (no dditionl compction), for three soil depths on cly lom soil t the Ottw Ntionl Forest. Men vlues for ech compction tretment re pooled cross ll orgnic mtter removl tretments. Brs with common letters indicte mens were not signifi cntly different (p 0.05). Signifi cnce tests of compction tretments pply within ech soil depth ctegory only. Dshed horizontl lines re men prehrvest ulk density vlues, pooled cross ll tretments y depth. Note: comprisons for tretment C 2 re pproximted y the nlysis ecuse n=1 for this tretment; the vlue shown is not true men nd the stndrd error used is the estimted vlue for the comprisons. Figure 8. Mens nd stndrd errors for ulk density of compction tretments t cm immeditely fter tretment (yr 0) nd 10 yers fter tretment (yr 10) for the cly lom soil t the Ottw Ntionl Forest. Brs with common letters indicte mens re not signifi cntly different (p 0.05). Dshed horizontl line is the men prehrvest ulk density pooled cross ll tretments. Compction tretments re constrined to OM 0. Note: comprisons for tretment C 2 re pproximted y the nlysis ecuse n=1 for this tretment; the vlue shown if not true men nd the stndrd error used is the estimted vlue for the comprisons. Soil Chemicl Chrcteristics Lomy Snd Soil At yer 10, no significnt differences (p > 0.05) were detected in totl cron or totl nitrogen etween the control nd ny compction or orgnic mtter removl tretment t ny depth (Tle 2). For most other vriles, no significnt differences were detected, except CECe nd C were significntly lower thn control for the OM 2 tretment t cm nd N ws significntly greter thn control for the C 2 tretment t cm (Tle 2). Silt Lom Soil At yer 10, no significnt differences were detected in totl cron or totl nitrogen etween the control nd ny compction or orgnic mtter removl tretment t ny depth (Tle 3). Moreover, CECe, C, nd N did not differ etween the control nd ny compction or orgnic mtter removl tretment t either depth (Tle 3). Potsium ws significntly lower thn the control in the OM 1 nd OM 2 tretments t cm, nd Mg ws significntly lower for tretments C 1 t cm nd C 2 t cm (Tle 3). Cly Lom Soil At yer 10, no significnt differences were detected in totl cron or totl nitrogen etween the control nd ny compction or orgnic mtter removl tretment t ny depth (Tle 4). Moreover, CECe, C, K, nd Mg did not differ etween the control nd ny compction or orgnic mtter removl tretment t either depth, while N ws significntly lower thn the control t cm for oth C 1 nd OM 1 tretments (Tle 4). 10
Tle 2. Mens (±stndrd errors) of soil chemicl vriles for orgnic mtter removl nd compction tretments nd the control t yer 10 on lomy snd soil (Huron Ntionl Forest). Soil depth CECe C K Mg N Totl C Totl N Tretment cm cmol kg -1 Mg h -1 1.937 ±0.389 1.518 ±0.325 0.106 ±0.011 0.292 ±0.063 0.021 ±0.005 16.38 ±3.16 0.88 ±0.19 C 0, OM 0 0.630 ±0.040 0.458 ±0.041 0.068 ±0.008 0.097 ±0.006 0.007 ±0.001 10.10 ±0.70 0.70 ±0.03 20-30 ----- ----- ----- ----- ----- 10.53 ±1.06 0.77 ±0.04 1.662 ±0.105 1.302 ±0.104 0.087 ±0.007 0.256 ±0.010 0.017 ±0.007 18.10 ±1.18 0.99 ±0.18 OM 1 0.846 ±0.142 0.648 ±0.123 0.081 ±0.016 0.111 ±0.025 0.005 ±0.001 11.11 ±1.49 0.706 ±0.06 20-30 ----- ----- ----- ----- ----- 9.70 ±1.97 0.71 ±0.12 1.278* ±0.105 0.952* ±0.087 0.082 ±0.007 0.222 ±0.025 0.022 ±0.005 12.22 ±3.03 0.82 ±0.20 OM 2 0.521 ±0.095 0.372 ±0.097 0.071 ±0.021 0.072 ±0.010 0.006 ±0.003 11.28 ±1.81 0.76 ±0.09 20-30 ----- ----- ----- ----- ----- 8.84 ±0.74 0.66 ±0.08 1.677 ±0.287 1.313 ±0.276 0.124 ±0.017 0.225 ±0.029 0.015 ±0.007 13.69 ±3.37 0.85 ±0.07 C 1 0.569 ±0.114 0.412 ±0.103 0.063 ±0.007 0.075 ±0.014 0.019 ±0.004 9.09 ±0.66 0.79 ±0.09 20-30 ----- ----- ----- ----- ----- 10.33 ±0.34 0.73 ±0.06 1.459 ±0.266 1.128 ±0.237 0.105 ±0.018 0.219 ±0.016 0.007 ±0.003 17.88 ±3.03 0.88 ±0.12 C 2 0.561 ±0.068 0.392 ±0.069 0.071 ±0.002 0.078 ±0.003 0.021* ±0.002 15.06 ±2.65 0.92 ±0.04 20-30 ----- ----- ----- ----- ----- 12.01 ±0.79 1.10 ±0.19 C 0,OM 0 (control) = no dditionl compction nd ole only hrvest, C 1 = medium compction, C 2 = hevy compction, OM 1 = totl tree hrvest, OM 2 = totl tree hrvest + forest fl oor removl. Note: orgnic mtter tretment mens constrined to C 0. Compction tretment mens constrined to OM 0. *Indictes signifi cnt difference from the control (C 0, OM 0 ) t p 0.05. 11
Tle 3. Mens (±stndrd errors) of soil chemicl vriles for orgnic mtter removl nd compction tretments nd the control t yer 10 on silt lom soil (Chippew Ntionl Forest). Soil Depth CECe C K Mg N Totl C Totl N Tretment cm cmol kg -1 Mg h -1 5.403 ±0.466 4.305 ±0.422 0.239 ±0.011 0.831 ±0.092 0.028 ±0.012 17.44 ±0.62 1.14 ±0.05 C 0, OM 0 3.326 ±0.489 2.423 ±0.364 0.199 ±0.014 0.692 ±0.142 0.012 ±0.005 6.58 ±0.72 0.63 ±0.02 20-30 ----- ----- ----- ----- ----- 3.33 ±1.05 0.48 ±0.06 4.358 ±1.150 4.457 ±1.101 0.195 ±0.010 0.686 ±0.058 0.007 ±0.004 16.33 ±2.14 1.08 ±0.08 OM 1 2.873 ±0.322 2.197 ±0.312 0.142* ±0.007 0.522 ±0.051 0.012 ±0.004 5.01 ±0.26 0.58 ±0.05 20-30 ----- ----- ----- ----- ----- 2.42 ±0.70 0.54 ±0.03 5.467 ±0.734 3.940 ±0.665 0.206 ±0.023 0.647 ±0.057 0.007 ±0.004 16.85 ±1.83 1.12 ±0.11 OM 2 2.813 ±0.335 2.108 ±0.290 0.151* ±0.020 0.531 ±0.058 0.023 ±0.004 7.65 ±2.58 0.62 ±0.02 20-30 ----- ----- ----- ----- ----- 1.97 ±0.31 0.47 ±0.03 4.725 ±0.500 3.910 ±0.480 0.220 ±0.011 0.572* ±0.025 0.023 ±0.010 15.95 ±3.40 1.17 ±0.15 C 1 2.928 ±0.281 2.182 ±0.209 0.157 ±0.013 0.553 ±0.064 0.037 ±0.013 4.75 ±1.59 0.67 ±0.10 20-30 ----- ----- ----- ----- ----- 2.46 ±0.15 0.49 ±0.05 5.573 ±1.053 4.637 ±0.980 0.251 ±0.033 0.669 ±0.062 0.016 ±0.009 18.27 ±2.40 1.19 ±0.14 C 2 2.841 ±0.378 2.195 ±0.367 0.157 ±0.011 0.461* ±0.041 0.028 ±0.010 8.44 ±2.77 0.69 ±0.08 20-30 ----- ----- ----- ----- ----- 2.35 ±0.14 0.45 ±0.02 C 0,OM 0 (control) = no dditionl compction nd ole only hrvest, C 1 = medium compction, C 2 = hevy compction, OM 1 = totl tree hrvest, OM 2 = totl tree hrvest + forest fl oor removl. Note: orgnic mtter tretment mens constrined to C 0. Compction tretment mens constrined to OM 0. *Indictes signifi cnt difference from the control (C 0, OM 0 ) t p 0.05. 12
Tle 4. Mens (±stndrd errors) of soil chemicl vriles for orgnic mtter removl nd compction tretments nd the control t yer 10 on cly lom soil (Ottw Ntionl Forest). Soil Depth CECe C K Mg N Totl C Totl N Tretment cm cmol kg -1 Mg h -1 8.622 ±0.935 6.600 ±0.742 0.329 ±0.043 1.686 ±0.232 0.007 ±0.001 28.68 ±3.79 1.52 ±0.15 C 0, OM 0 11.072 ±1.394 7.600 ±0.980 0.450 ±0.046 2.906 ±0.368 0.117 ±0.016 10.67 ±0.27 0.81 ±0.03 20-30 ----- ----- ----- ----- ----- 7.62 ±0.09 0.66 ±0.03 7.963 ±0.301 5.880 ±0.248 0.335 ±0.006 1.735 ±0.048 0.012 ±0.004 30.22 ±3.43 1.67 ±0.12 OM 1 10.830 ±0.342 7.240 ±0.201 0.439 ±0.016 3.083 ±0.137 0.067* ±0.010 11.55 ±1.09 0.89 ±0.06 20-30 ----- ----- ----- ----- ----- 8.18 ±0.47 0.69 ±0.02 8.521 ±0.565 6.167 ±0.433 0.370 ±0.020 1.972 ±0.134 0.012 ±0.006 31.18 ±3.59 1.67 ±0.17 OM 2 10.700 ±1.106 7.200 ±0.757 0.427 ±0.018 2.983 ±0.312 0.089 ±0.026 12.40 ±1.50 0.94 ±0.03 20-30 ----- ----- ----- ----- ----- 9.31 ±1.35 0.67 ±0.01 7.515 ±0.259 5.425 ±0.125 0.303 ±0.029 1.771 ±0.113 0.017 ±0.001 32.78 ±3.39 1.85 ±0.08 C 1 10.986 ±0.796 7.225 ±0.525 0.405 ±0.018 3.275 ±0.242 0.081* ±0.011 10.27 ±0.59 0.95 ±0.01 20-30 ----- ----- ----- ----- ----- 7.49 ±0.07 0.67 ±0.03 8.034 5.750 0.362 1.908 0.014 26.35 1.54 C 2 12.218 8.20 0.456 3.483 0.078 10.09 0.82 20-30 ----- ----- ----- ----- ----- 8.81 0.75 C 0,OM 0 (control) = no dditionl compction nd ole only hrvest, C 1 = medium compction, C 2 = hevy compction, OM 1 = totl tree hrvest, OM 2 = totl tree hrvest + forest fl oor removl. Note: orgnic mtter tretment mens constrined to C 0. Compction tretment mens constrined to OM 0. Vlues re not mens of replictes s C 2 OM 0 t Ottw hd only 1 replicte (n = 1). *Indictes signifi cnt difference from the control (C 0, OM 0 ) t p 0.05. 13
Vegettion Responses Lomy Snd Soil Both totl oveground woody iomss nd spen iomss t yer 10 were significntly lower for the OM 2 tretment thn the control. Aspen iomss ws significntly greter thn the control for C 1 tretment nd totl iomss ws mrginlly higher thn the control for this tretment. Herceous iomss, totl stem density, nd spen stem density did not differ significntly etween the control nd ny compction or orgnic mtter removl tretments (Fig. 9). Silt Lom Soil Both totl oveground woody iomss nd men spen iomss were significntly less for the OM 2, C 1 nd C 2 tretments thn for the control. C 1 nd C 2 hd significntly higher herceous iomss thn the control nd C 2 lso hd significntly lower totl stem density compred to control (Fig. 10). Cly Lom Soil On the cly lom soil, the C 1 tretment hd significntly higher totl iomss compred to the control. Totl iomss nd spen iomss were significntly higher thn control for the OM 2 tretment. Herceous iomss, totl stem density, nd spen stem density were not significntly different from the control for ny of the tretments (Fig. 11). 30 C0OM0 OM1 100000 25 OM2 C1 80000 20 C2 Mg h -1 15 10 Stems h -1 60000 40000 5 20000 0 0 Totl Aspen Herceous Totl Aspen Biomss Density Figure 9. Mens nd stndrd errors for oveground iomss nd density of vegettion groups 10 yers fter ppliction of OM 1 (whole-tree hrvest), OM 2 (whole-tree hrvest plus forest fl oor removl), C 1 (medium), nd C 2 (hevy) compction tretments, reltive to C 0 OM 0 (control: ole only hrvest nd no dditionl compction) on lomy snd soil t the Huron Ntionl Forest. Brs with n sterisk indicte mens were signifi cntly different from the control (p 0.05). 14
50 40 C0OM0 OM1 OM2 C1 C2 100000 80000 Mg h -1 30 20 Stems h -1 60000 40000 10 20000 0 0 Totl Aspen Herceous Totl Aspen Biomss Density Figure 10. Mens nd stndrd errors for oveground iomss nd density of vegettion groups 10 yers fter ppliction of OM 1 (whole-tree hrvest), OM 2 (whole-tree hrvest plus forest fl oor removl), C 1 (medium), nd C 2 (hevy) compction tretments, reltive to C 0 OM 0 (control: ole only hrvest nd no dditionl compction) on silt lom soil t the Chippew Ntionl Forest. Brs with n sterisk indicte mens were signifi cntly different from the control (p 0.05). 20 15 C0OM0 OM1 OM2 C1 C2 50000 40000 Mg h -1 10 Stems h -1 30000 20000 5 10000 0 0 Totl Aspen Herceous Totl Aspen Biomss Density Figure 11. Mens nd stndrd errors for oveground iomss nd density of vegettion groups 10 yers fter ppliction of OM 1 (whole-tree hrvest), OM 2 (whole-tree hrvest plus forest fl oor removl), C 1 (medium), nd C 2 (hevy) compction tretments, reltive to C0OM0 (control: ole only hrvest nd no dditionl compction) on cly lom soil t the Ottw Ntionl Forest. Brs with n sterisk indicte mens were signifi cntly different from the control (p 0.05). Note: n=1 for tretment C 2 ; it ws not included in the nlysis. 15
DISCUSSION In this study, we sked if there ws n effect from orgnic mtter removl or soil compction on soil physicl nd chemicl properties, 10 yers fter tretment ppliction, nd t wht level of tretment n effect ws evident. The compction tretments incresed soil ulk density ove prehrvest levels for ll three soil types nd t ll soil depths, ut prticulrly t cm. Generlly, the increse in ulk density prlleled the incresing intensity of the compction tretment. Moreover, ulk densities generlly remined ove pretretment levels on ll soil types, 10 yers fter tretment, prticulrly t cm. However, y yer 10, ulk density t cm decresed nd compction tretments were no longer significntly different from control, except on the cly lom soil where the high compction tretment remined significntly greter thn the no-dditionl compction tretment. Bulk density t the deeper soil depths remined significntly greter thn control for oth compction tretments on the lomy snd soil. Overll, y yer 10, orgnic mtter removl tretments hd little effect on the soil properties we exmined on ny of the soil types. Soil chemicl responses were generlly miniml nd specific to soil texture. On the lomy snd soil (Huron Ntionl Forest), CECe nd C were significntly lower t the cm soil depth with totl tree plus forest floor removl, reltive to the control. It ppers tht the removl of forest floor orgnic mtter, in ddition to totl tree hrvest, my result in lower C concentrtions in the upper most 10 cm in the lomy snd soil. This my result in decresed inputs of C to the soil, fter removl of the forest floor, nd/or incresed leching for short period of time. On the silt lom soil (Chippew Ntionl Forest), Mg ws significntly less for the moderte compction tretment t cm nd the hevy compction tretment t cm, while K ws significntly less thn the control with totl tree plus forest floor removl t cm. On the cly lom soil (Ottw Ntionl Forest), only one soil chemicl mesure (N in C 1 t cm) differed significntly from the control t yer 10. Is there n effect of tretment on vegettion productivity nd undnce fter 10 yers nd t wht level of orgnic mtter removl or compction is n effect evident? On the lomy snd soil (Huron Ntionl Forest), oth totl woody nd spen iomss were significntly less with totl tree hrvest plus forest floor removl thn the control, ut iomss in the totl tree hrvest tretment did not differ from the control. Possily, the decrese in iomss resulted from the reduction in C tht ws lso noted in this tretment. Also t yer 10, moderte compction on the lomy snd soil significntly incresed spen iomss compred to the control. A similr response for spen iomss ws found t yer 5 nd ws ttriuted to incresed wter-holding cpcity due to conversion of some mcropores to micropore spce with moderte compction (Stone et l. 1998). This is consistent with results from n nlysis of other LTSP sites, where iomss production incresed with compction on snd soils (Powers et l. 2005), presumly due to improved moisture sttus. However, our dt lso show tht hevy compction did not result in further improvements in moisture sttus ove moderte compction. On the silt lom soil (Chippew Ntionl Forest), totl iomss nd spen iomss were significntly less thn the control with totl tree hrvest plus forest floor removl nd with oth levels of compction. Moreover, totl stem density ws lower thn the control on the highest compction tretment. Neither totl iomss nor spen iomss differed from the control with totl tree hrvest lone. The reduction of iomss with totl tree plus forest floor removl is proly not due to the reduction in K with this tretment, s K limittions re rre in most forests. Reductions in iomss with the compction tretments likely ws due to reductions in mcropores, incresed root restriction, reduced wter infiltrtion rtes, nd ltered gseous exchnge (Aln 1991, Grecen nd Snds 1980). Moreover, the timing of the compction tretments t this site my hve plyed significnt role in the iomss reduction noted. Compction tretments were pplied in lte spring fter spen suckering hd lredy egun nd resulted in some destruction of these suckers y the compction equipment (Stone 2001, 2002, Stone nd Kzems 2002). The extent to which this my hve impcted spen resuckering nd susequent iomss growth my hve een significnt. While ppliction of compction tretments fter spen suckering likely 16
hd some impct on spen regrowth, it is cler tht totl iomss nd spen iomss were gretly reduced y oth moderte nd high compction, likely due to incresed ulk densities with these tretments, which in turn my hve resulted in reduced ertion nd moisture vilility. Herceous iomss t yer 10 ws significntly greter on the two compction tretments nd my reflect reduced shding nd competition with less woody vegettion on these tretments. On the cly lom soil (Ottw Ntionl Forest), totl tree hrvest with forest floor removl significntly incresed oth totl nd spen iomss, while totl tree hrvesting lone did not differ significntly from min ole only hrvesting. The explntion for this is not pprent. Moderte compction significntly incresed totl iomss, suggesting tht this level of compction my hve improved moisture sttus. Hevy compction ppered to reduce oth totl nd spen iomss reltive to the control, lthough there ws only one replicte for this lter tretment, so comprisons should e mde with cution. However, the ltter result is consistent with results from n nlysis of other LTSP sites, which showed tht iomss production generlly declined with high compction on cly soils (Powers et l. 2005). One explntion for incresed oveground iomss production with oth the totl tree hrvest plus forest floor removl nd moderte compction tretments is tht growth of individul spen suckers my hve een stimulted y the ppliction of these tretments, while competition y less disturnce-tolernt species my hve een reduced. In contrst, the hevy compction tretment, with incresed ulk density t cm, my hve dmged nd destroyed mny plnt propgules, including tree roots. Mngement Implictions If min ole hrvest with no dditionl compction is the stndrd ginst which to judge other tretments, then the tenth yer results for spen forests suggest tht ll three soil types cn tolerte totl tree hrvest, with no dditionl compction, without significnt reductions in totl woody or spen iomss production, s long s there is no dditionl compction. The ddition of forest floor removl to the totl tree hrvest resulted in negtive impcts on iomss production for the lomy snd nd silt lom soils, ut hd significnt positive effects on the cly lom soil. The cvet for these conclusions is tht they re sed on reltively short-term (10 yers) dt; potentilly, results could differ in future yers. However, our results re supported y study compring min ole nd whole-tree hrvesting in other spen ecosystems (Aln nd Perl 1988), in which neither tretment negtively impcted soil properties in the short-term (8 yers or less), even though whole-tree hrvesting removed s much s 40 percent of the ville ecosystem C nd significnt mounts of other nutrients in the upper minerl soil nd forest floor. In Aln nd Perl s study, nnul litterfll mss returned to prehrvest levels within 6 yers nd there were no differences etween the two hrvesting systems in forest floor weight, vegettive regrowth, nd soil cron. Our results suggest tht hevy compction is likely is e detrimentl to woody plnt production, t lest in the short term. Moderte compction my ctully stimulte production on some soils (lomy snd nd cly lom). However, we do not recommend tht controlled compction e used s tool to improve productivity, s controlling the level of ppliction would e difficult. Rther, the gol should e to minimize compction to the extent possile in ll cses. The long-term impcts on site qulity nd productivity of whole-tree hrvesting nd compction remin lrgely unknown. For exmple, long-term impcts for soil ction depletion, for exmple C reduction on the lomy snd soil, remin unknown given tht the spen stnds we studied re still reltively young nd nutrient demnding (Aln nd Perl 1990). Shorter rottions with more frequent entries for whole-tree tree hrvests for iomss feedstocks dd to tht uncertinty of response nd the need for cution. Long-term reserch such s the LTSP progrm is essentil for incresing our understnding of these responses. ACKNOWLEDGMENTS We re grteful to the Forest Service soil scientists tht hve supported this work over the lst decde, especilly Srh Mse, Joe Gtes, Jim Brrot, Neil Bik, nd Dve Shdis. We thnk Mry Beth Adms nd Rndy Kolk for helpful comments on n erlier version of this report nd John Stnovick for sttisticl support. 17
LITERATURE CITED Aln, D.H. 1991. The impct of spen hrvesting on site productivity. In: Nvrtil, S.; Chpmn, P.B., eds. Aspen mngement for the 21st century: proceedings of the symposium; 1990 Novemer 20-21; Edmonton, Alert: Forestry Cnd Northwest Regionl Northern Forest Center nd Poplr Council: 71-76. Aln, D.H.; Perl, D.A. 1990. Impct of spen timer hrvesting on soils. In: Gessel, S.P.; Lctte, D.S.; Weetmn, G.F.; Powers, R.F., eds. Sustined productivity of forest soils: proceedings of the 7th North Americn forest soils conference: 1988 July 24-28; Vncouver, British Columi: University of British Columi, Fculty of Forestry Puliction: 377-391. Bllrd, T.M. 2000. Impcts of forest mngement on northern forest soils. Forest Ecology nd Mngement. 133: 37-42. Grecen, E.L.; Snds, R. 1980. Compction of forest soils: review. Austrlin Journl of Soil Reserch. 18: 163-189. Grigl, D.F. 2000. Effects of extensive forest mngement on soil productivity. Forest Ecology nd Mngement. 138: 167-185. Hendrickson, O.Q.; Chtrpul, L.; Burgess, D. 1989. Nutrient cycling following whole-tree nd conventionl hrvest in northern mixed forest. Cndin Journl of Forest Reserch. 19: 725-735. Littell, R.C.; Milliken, G.A.; Stroup, W.W.; Wolfinger, R.D. 1996. SAS system for mixed models. Cry, NC: SAS Institute. 633 p. Lugo, A.E.; Brown, S.L.; Dodson, R.; Smith, T.S.; Shugrt, H.H. 1999. Specil pper: the Holdridge life zones of the conterminous United Sttes in reltion to ecosystem mpping. Journl of Biogeogrphy. 26: 1025-1038. Pge-Dumroese, D.; Jurgensen, M.; Elliot, W.; Rice, T.; Nesser, J.; Collins, T.; Meurisse, R. 2000. Soil qulity stndrds nd guidelines for forest sustinility in northwestern North Americ. Forest Ecology nd Mngement. 138: 445-462. Perl, D.A.; Aln, D.H. 1993. Allometric iomss estimtors for spen-dominted ecosystems in the upper Gret Lkes. Res. Pp. NC-314. St. Pul, MN: U.S. Deprtment of Agriculture, Forest Service, North Centrl Forest Experiment Sttion. 42 p. Powers, R.F. 1999. On the sustinle productivity of plnted forests. New Forests. 17: 263-306. Powers, R.F. 2006. Long-term soil productivity: genesis of the concept nd principles ehind the progrm. Cndin Journl of Forest Reserch. 36: 519-528. Powers, R.F.; Aln, D.H.; Miller, G.H.; Tirks, A.E. 1990. A soils reserch pproch to evluting mngement impcts on long-term productivity. In: Dyck, W.J.; Mees, C.A., eds. Impct of intensive hrvesting on forest site productivity. Forestry Reserch Institute Bulletin No. 159. Rotoru, New Zelnd: Forestry Reserch Institute: 67-99. Powers, R.F.; Aln, D.H.; Miller, R.E.; Tirks, A.E.; Wells, C.G.; Avers, P.E.; Cline, R.G.; Fitzgerld, R.O.; Loftus, N.S., Jr. 1990. Sustining site productivity in North Americn forests: prolems nd prospects. In: Gessel, S.P.; Lctte, D.S.; Weetmn, G.F.; Powers, R.F., eds. Sustined productivity of forest soils: proceedings of the 7th North Americn forest soils conference: 1988 July 24-28; Vncouver, British Columi: University of British Columi, Fculty of Forestry Puliction: 49-79. 18
Powers, R.F.; Snchez, F.G; Scott, D.A.; Pge- Dumroese, D. 2004. The North Americn long-term soil productivity experiment: cost-to-cost findings from the first decde. In: Shepperd, W.D.; Eskew, L.G., compilers. Silviculture in specil plces: proceedings of the Ntionl Silviculture Workshop; 2003 Septemer 8-11: Grny, CO. Proceedings RMRS-P-34. Fort Collins, CO: U.S. Deprtment of Agriculture, Forest Service, Rocky Mountin Reserch Sttion: 191-206. Powers, R.F.; Scott, D.A.; Snchez, F.G.; Voldseth, R.A.; Pge-Dumroese, D.; Elioff, J.D.; Stone, D.M. 2005. The North Americn long-term soil productivity experiment: findings from the first decde of reserch. Forest Ecology nd Mngement. 220: 31-50. Pritchett, W.L.; Fisher, R.F. 1987. Properties nd Mngement of Forest Soils, 2nd edition. Hooken, NJ: John Wiley & Sons. 494 p. Ross, D.S. 1995. Recommended methods for determining soil ction exchnge cpcity. In: Sims, J.T.; Wolf, A., eds. Recommended soil testing procedures for the northestern United Sttes. Northest Regionl Puliction No. 493. Newrk, DE: Agriculturl Experiment Sttion, University of Delwre: 62-70. SAS Institute Inc. 1999. SAS for Windows version 8. Cry, NC: SAS Institute Inc. 357 p. Schulte, L.A.; Mldenoff, D.J.; Crow, T.R.; Merrick, L.C.; Clelnd, D.T. 2007. Homogeniztion of northern U.S. Gret Lkes forests due to lnd use. Lndscpe Ecology. 22: 1089-1103. Spilke, J.; Piepho, H.P.; Hu, X. 2005. Anlysis of unlnced dt y mixed liner models using the MIXED procedure of the SAS system. Journl of Agronomy nd Crop Science. 191: 47-54. Stone, D.M.; Gtes, J.A.; Elioff, J.D. 1998. Are we mintining spen productivity on lomy snd soils? In: ZumBhlen, B.; Ek, A.R., eds. Improving forest productivity for timer: proceedings of the conference; 1998 Decemer 1-3; Minnepolis, MN: Deprtment of Forest Resources, University of Minnesot: 177-184. Stone, D.M. 2001. Sustining spen productivity in the lke sttes. In: Shepperd, W.D.; Binkley, D.; Brtos, D.L.; Stohlgren, T.J.; Eskew, L.G., compilers. Sustining spen in western lndscpes. Proceedings RMRS-P-18. Fort Collins, CO: U.S. Deprtment of Agriculture, Forest Service, Rocky Mountin Reserch Sttion: 47-59. Stone, D.M. 2002. Lke sttes spen productivity following compction nd orgnic mtter removl. In: Prker, S.; Hummel, S.S., compilers. Beyond 2001: A silviculturl odyssey to sustining terrestril nd qutic ecosystems: proceedings of the 2001 Ntionl Silviculturl Workshop; 2001 My 6-10; Hood River, OR. Gen. Tech. Rep. PNW-546. Portlnd, OR: U.S. Deprtment of Agriculture, Forest Service, Pcific Northwest Reserch Sttion: 59-67. Stone, D.M.; Kzems, R. 2002. Aspen development on similr soils in Minnesot nd British Columi fter compction nd forest floor removl. The Forestry Chronicle. 78: 886-891. Tirks, A.E.; Buford, M.A.; Powers, R.F.; Rgus, J.F.; Pge-Dumroese, D.S.; Ponder, F., Jr.; Stone, D. 1997. North Americn long-term soil productivity reserch progrm. In: Communicting the role of silviculture in mnging the Ntionl Forests: proceedings of the ntionl silviculturl workshop; 1997 My 19-22; Wrren, PA. Gen. Tech. Rep. NE-238. Rdnor, PA: U.S. Deprtment of Agriculture Forest Service, Northestern Forest Experiment Sttion: 140-147. Wlmsley, J.D.; Jones, D.L.; Reynolds, B.; Price, M.H.; Heley, J.R. 2009. Whole tree hrvesting cn reduce second rottion forest productivity. Forest Ecology nd Mngement. 257: 1104-1111. 19
Wolf, A.; Beegle, D. 1995. Recommended soil tests for mcronutrients: Phosphorus, potssium, clcium, nd mgnesium. In: Sims, J.T.; Wolf, A., eds. Recommended soil testing procedures for the northestern United Sttes. Northest Regionl Puliction No. 493. Newrk, DE: Agriculturl Experiment Sttion, University of Delwre: 71-83. Zowski, D.; Skinner, M.F.; Rygiewicz, P.T. 1994. Timer hrvesting nd long-term productivity: wethering processes nd soil disturnce. Forest Ecology nd Mngement. 66: 55-68. 20
Voldseth, Richrd; Plik, Brin; Elioff, John. 2011. Ten-yer Results from the Long-term Soil Productivity Study in Aspen Ecosystems of the Northern Gret Lkes Region. Res. Pp. NRS-17. Newtown Squre, PA: U.S. Deprtment of Agriculture, Forest Service, Northern Reserch Sttion. 20 p. Impcts of orgnic mtter removl nd compction on soil properties nd productivity re reported from the fi rst 10 yers of the Long-Term Soil Productivity Study in Gret Lkes spen ecosystems. Orgnic mtter removl tretments included min ole, totl tree hrvest, nd totl tree hrvest with forest fl oor removl. Compction tretments included miniml compction, moderte, nd hevy compction. Tretments were replicted on cly lom, silt lom, nd lomy snd soils. Compction tretments on ll soils incresed ulk density ove prehrvest levels. In most cses, ulk density t yer 10 ws still ove prehrvest levels. Totl cron, nitrogen, nd ctions showed little or no impct from tretment. Compction nd orgnic mtter removl impcted oveground productivity, however the responses were vrile. Aoveground production declined on the lom soil with moderte nd hevy compction. Production incresed with moderte compction on the lomy snd nd cly lom soils, ut signifi cntly decresed with hevy compction on cly lom soil. Totl tree hrvest with forest fl oor removl reduced production on the lomy snd nd lom soils, while it incresed production on the cly lom soil. Results from this study suggest tht hevy compction nd/or high orgnic mtter removls re detrimentl to sustining forest productivity. KEY WORDS: Long-term soil productivity (LTSP), whole-tree hrvesting, iomss hrvesting, ioenergy, tremling spen, soil compction, orgnic mtter removl, hrvesting impcts The U.S. Deprtment of Agriculture (USDA) prohiits discrimintion in ll its progrms nd ctivities on the sis of rce, color, ntionl origin, ge, disility, nd where pplicle, sex, mritl sttus, fmilil sttus, prentl sttus, religion, sexul orienttion, genetic informtion, politicl eliefs, reprisl, or ecuse ll or prt of n individul s income is derived from ny pulic ssistnce progrm. (Not ll prohiited ses pply to ll progrms.) Persons with disilities who require lterntive mens for communiction of progrm informtion (Brille, lrge print, udiotpe, etc.) should contct USDA s TARGET Center t 202-720-2600 (voice nd TDD). To fi le complint of discrimintion, write USDA, Director, Office of Civil Rights, 1400 Independence Avenue SW, Wshington, DC 20250-9410, or cll 800-795-3272 (voice) or 202-720-6384 (TDD). USDA is n equl opportunity provider nd employer. Printed on recycled pper
www.nrs.fs.fed.us