ORIGINAL PAPER

Effects of climatic and soil properties on cellulosedecomposition rates in temperate and tropical forests

Chie Hayakawa & Shinya Funakawa & Kazumichi Fujii &Atsunobu Kadono & Takashi Kosaki

Received: 16 July 2013 /Revised: 20 October 2013 /Accepted: 28 October 2013 /Published online: 16 November 2013# Springer-Verlag Berlin Heidelberg 2013

Abstract Cellulose decomposition experiments were con-ducted under field conditions to analyze the effects of climaticand soil properties on rates of organic matter decomposition intemperate and tropical forests. The mass loss rates of cellulosefilter papers buried in the soil surface were measured toestimate the respiratory C fluxes caused by cellulose decom-position and mean residence time (MRT) of cellulose. Therates of cellulose decomposition increased with soil tempera-ture, except for during the dry season, while rate constants ofdecomposition (normalized for temperature) decreased withdecreasing pH because of lower cellulase activity. The esti-matedMRTs of soil cellulosic carbohydrates varied from 81 to495 days for the temperate forests and from 31 to 61 days forthe tropical forests. As a major organic substrate, the C fluxesfrom cellulose decomposition can account for a substantialfraction of heterotrophic (basal) soil respiration. However, therespiratory C fluxes can be limited by the low substrateavailability and low pH in tropical soils, despite high micro-bial activity. The rate-regulating factors of cellulose

decomposition, i.e., temperature, soil pH, and substrate avail-ability, can accordingly influence the rates of heterotrophicsoil respiration.

Keywords Basal soil respiration . Cellulose test . Cellulase .

Soil organic matter . Tropical forest

Introduction

Organic matter decomposition is a key process regulat-ing the storage of soil organic C (SOC) and nutrientsupply in forest ecosystems (Berg and McClaugherty2003). The decomposition rate and C storage can bedescribed by existing SOC models using a simple con-cept of first-order decay (Jenkinson et al. 1990); how-ever, the wide variation in microbial responses to thevarying environmental conditions (e.g., in differing soiltypes such as volcanic soil and tropical soil) remains tobe studied (Zunino et al. 1982; Shirato et al. 2004).Rate-regulating factors need to be analyzed holisticallyand individually for two-step decomposition of polymer-ic soil organic matter (SOM) including the extracellularenzymatic reaction (Allison et al. 2010).

Owing to the importance of carbohydrates in SOC dynam-ics, cellulose has been studied as a model compound ofpolymeric SOM (Withington and Stanford 2007). Cellulose,like lignin, is a major constituent of plant materials (10–87 %from Berg and McClaugherty 2003) and thus accounts for asignificant proportion of organic C input into the soil (Pauland Clark 1996; Stevenson 1982). Recently, carbohydrateswere found to be major sources for heterotrophic soil respira-tion (Hayakawa et al. 2011; Kiem and Kögel-Knabner 2003)and SOC stabilization (Cheshire 1979; Stevenson 1982).Decomposition of cellulose can roughly be divided into twosteps: solubilization by enzymes and mineralization of

C. Hayakawa : S. Funakawa :K. FujiiGraduate School of Agriculture, Kyoto University, Kyoto 606-8502,Japan

C. Hayakawa (*)National Institute for Agro-Environmental Science,Ibaraki 305-8604, Japane-mail: chayakawa@affrc.go.jp

K. FujiiForestry and Forest Products Research Institute, Ibaraki 305-8687,Japan

A. KadonoTottori University of Environmental Studies, Tottori 689-1111, Japan

T. KosakiDepartment of Tourism Science, Tokyo Metropolitan University,Tokyo 192-0364, Japan

Biol Fertil Soils (2014) 50:633–643DOI 10.1007/s00374-013-0885-4

monomers. The decomposition rates (or mass loss) of cellu-lose depend mainly on solubilization (hydrolysis) by micro-bial cellulases (Hopkins et al. 1990; Qualls 2000). Oncepolysaccharides are solubilized, monosaccharides are rapidlymineralized with a mean residence time (MRT) less thanseveral hours (Schneckenberger et al. 2008; Van Hees et al.2008). By comparing MRTs of cellulose and glucose in soils,the rate-limiting steps and the environmental factors control-ling decomposition rates can be analyzed (Elmajdoub andMarschner 2013).

Field “litter bag” incubations demonstrated that cel-lulose decomposition rates could vary depending onchemical composition of foliar litter (e.g., lignin and Nconcentrations), as well as climatic and soil factors(Berg and McClaugherty 2003). Conversely, incubationof the standard simple substrate—cellulose filter paper—allows us to identify the dominant rate-regulating factorsof decomposition among sites under different environ-mental conditions (Drewnik 2006). Both the field andlaboratory incubation studies have shown that cellulosedecomposition increases with soil temperature and mois-ture content (Drewnik 2006; Kim 2010). Laboratoryincubation studies have demonstrated that soil physico-chemical properties, pH, SOC, N, and clay contents alsohave strong influences on decomposition rates (Rascheand Cadish 2013; Sorensen 1975). In humid Asia, high-ly acidic tropical soils and volcanic soils can be foundof a large range of pH, clay, and SOC contents, whichcan influence the wide variation in MRTs of cellulose(Zunino et al. 1982). Although laboratory studies haveidentified the effects of individual soil properties oncellulose decomposition rates, their importance relativeto climatic factors under field conditions remainsunclear.

We hypothesized that (1) soil temperature is an over-whelmingly important factor regulating the microbialactivity of cellulose decomposition, and therefore de-composition rates are higher in tropical forests than intemperate forests, irrespective of soil physicochemicalproperties. To test this hypothesis, cellulose decomposi-tion experiments were conducted under field and labo-ratory conditions for the temperate and tropical forestsoils of humid Asia. We also hypothesized that (2) theC fluxes from cellulose decomposition in soils are de-pendent on substrate availability as well as microbialdecomposition activity. Therefore, it was expected thatrespiratory C fluxes would be limited by the low sub-strate availability in tropical soils, despite high microbi-al activity. To test this hypothesis, we estimated the Cfluxes caused by cellulose decomposition as well ascellulose MRTs, and analyzed the dominant rate-regulating factors of organic matter decomposition underfield conditions.

Materials and methods

Site description

This study was carried out in six natural broad-leaved forests:three temperate forests in Japan and three tropical forests inThailand and Indonesia (Table 1). Japanese sites include anAndisol site in Mt. Yatsugatake, Nagano (NG), a Spodosolsite in the Tango Peninsula (TG), and an Inceptisol site inKyoto (KT) (Table 1). The three tropical forests consisted oftwo moderately acidic Ultisol sites of Du La Poe (DP) andRakpaendin (RP) in northern Thailand and a highly acidicUltisol site of Bukit Soeharto (BS) in East Kalimantan,Indonesia (Table 1). All the soils were developed from sedi-mentary rocks, except for the NG site where the soil is derivedfrom volcanic ash. The mean annual air temperature andannual precipitation ranged from 6.9 to 26.8 °C, and 1,222to 2,084 mm year−1, respectively (Table 1). Three sites inJapan (NG, TG, and KT) belonged to a temperate humidclimate, while the BS site in Indonesia belonged to a tropicalhumid climate. Two sites in Thailand (RP and DP) had atropical monsoonal climate with distinct wet and dry seasons(April to September and October to March, respectively). Thesite and soil characteristics were described in detail by Fujiiet al. (2008, 2009) and Funakawa et al. (1997, 2006).

Physicochemical and microbiological properties of soils

Five composite soil samples were collected from the A hori-zon (0 to 5 cm depth) from each site at the start of the fieldincubation experiments. Soil samples were kept in plastic bagsat 4 °C prior to analysis and sieved (<2 mm) to eliminate litter,roots, and stones. A subsample of field-moist soil was used formeasurements of microbiological properties, while anothersubsample was air-dried and used for measurements of phys-icochemical properties.

The concentrations of total C and N in soils were measuredusing a CN analyzer (Vario Max CN, ElementarAnalysensystem GmbH). Soil pH was measured using a soilto solution (H2O) ratio of 1:5 (w /v ) after shaking for 1 h. Theconcentrations of exchangeable Al in soils were determinedby aluminon colorimetry (Hsu 1963). The particle size distri-bution was determined by the pipette method (Gee andBouder 1986). The concentrations of cellulosic and total car-bohydrates in soils were measured using two-step hydrolysisby H2SO4 (Oades et al. 1970). Briefly, 1.0 g of soil sampleswere hydrolyzed with 2.5 M H2SO4 for 20 min in an oil bath(110 °C) to obtain the first hydrolyzate regarded as noncellu-losic carbohydrates. The residues were hydrolyzed with 13 MH2SO4 for 16 h at room temperature, followed by treatmentwith 0.5 M H2SO4 for 5 h in an oil bath (at 105 °C), to obtainthe second hydrolyzate regarded as cellulosic carbohydrates.Hexose and pentose concentrations in both hydrolyzates were

634 Biol Fertil Soils (2014) 50:633–643

determined by absorption spectrophotometry using thephenol-sulfuric acid method and orcine-Fe-hydrochloric acidmethod, respectively (Fukui 1990).

The concentrations of inorganic N (NH4+ and NO3

−) in thefield-moist soils were measured by extraction with 2 M KClfor 30 min (soil to solution ratio of 1:5) (Mulvaney 1996;Rhine et al. 1998). Microbial biomass-C in soils was deter-mined in four replicates by the substrate-induced respiration(SIR) method (Anderson and Domesch 1978). After pre-incubation for 7 days (25 °C, 60 % of water holding capacity),the fresh soil samples (equivalent to 15 g DW soil) werethoroughly mixed with 150 mg solid glucose and 20 mgNH4NO3 and incubated at 25 °C for 80min. The CO2 evolvedfrom the soil was measured with an infrared CO2 controller(ZFP9, Fuji Electric Instruments Co., Ltd.). The SIR values(microliters CO2 per gram soil per hour) were converted intomicrobial biomass-C, as follows:

Microbial biomass‐C μg g−1soil� � ¼ μL CO2 g

−1soil h−1� �� 49:3

ð1Þ

To obtain an estimate of fungal activity in the soils, therelative contribution of fungi to glucose-induced respirationwas measured in three replicates by the selective inhibitionmethod (Joergensen andWichern 2008; Fujii et al. 2012). Thefield-moist soil samples were amended with a solution of 14C-labeled glucose with or without cycloheximide (fungal respi-ratory inhibitor; equivalent to 8 mg g−1soil, respectively) andincubated at 22 °C for 24 h. The contribution of fungi to totalmicrobial respiration (percent) was calculated using the dif-ferences between 14CO2 evolution rates of the glucose-amended soils with and without the inhibitor. As the use offungicide can sometimes induce nontarget effects (Landi et al.1993), these values were used as a rough estimate of fungalactivity in the soils in our study.

Monitoring soil temperature and volumetric water content

During field incubation periods, soil temperature (5 cm depth)was measured with a thermistor probe (Temperature Probe

108, Campbell Scientific Inc.) in two replicate locations. Thevolumetric water contents of the soils (5 cm depth) weremeasured with TDR probes (CS 616 probe, CampbellScientific, Inc.) in three replicates. The seasonal fluctuationsin soil temperature and water content were monitored andrecorded at 30-min intervals during the entire experimentalperiod (Funakawa et al. 2006; Fujii et al. 2008, 2009).

Measurement of the cellulose decomposition rate under fieldcondition

The decomposition rates of cellulose were estimated from themass loss of cellulose filter papers buried in the soil underfield condition (Beyer 1992). One piece of cellulose filterpaper (Advantec no. 6, 55 mm diameter) was packed in anylon mesh bag (size, 65×65mm; mesh pore size, 100 μm) tokeep out insects and worms, and was buried into the soilsurface (A horizon, 5 cm depth) to minimize the disturbanceof soil structure. At each site, five mesh bags were collected ateach sampling interval once per month (temperate forest) ortwice per month (tropical forest). The filter paper incubationwas carried out during the growing seasons of 2004 and2005 at NG, TG, and KT (Japan), while the incubations atRP and DP (Thailand) and BS (Indonesia) were conductedduring the wet then the dry seasons respectively during thistime.

The cellulose filter paper remaining in the mesh bag wasdried at 70 °C for 24 h and weighed after carefully removingsoil particles. The filter paper weight was calculated on an ash-free basis by subtracting the weight of the soil adhering to thefilter paper, estimated by dry combustion (600 °C, 4 h). Theproportion of remaining cellulose was calculated by dividingthe remaining weight by the initial weight of the filter paper.

Calculation of the rate constant of cellulose decomposition

Using the results of the filter paper field incubation, the rateconstant for cellulose decomposition was calculated based onSparrow et al. (1992). To normalize for the effects of soiltemperature on decomposition rates and to compare the effects

Table 1 Site description

Site Location MAT (°C) MAP (mm) Vegetation Soil (Soil Taxonomya)

Japan NG (N 35°57′, E 138°28′) 6.9 1,422 Quercus crispula Acrudoxic Melanudands

TG (N 35°37′, E 135°10′) 10.7 1,782 Fagus crenata Andic Haplohumods

KT (N 35°1′, E 135°47′) 15.9 1,490 Quercus serrata Typic Dystrudepts

Thailand RP (N 19°50′, E 100°20′) 25.0 2,084 Lithocarpus sp. Typic Haplustults

DP (N 18°24′, E 98°05′) 20.2 1,222 Lithocarpus sp. Ustic Haplohumults

Indonesia BS (S 0°51′, E 117°06′) 26.8 1,977 Shorea laevis Typic Paleudults

MAT mean annual air temperature, MAP mean annual precipitationa Soil survey staff (2006)

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of environmental factors other than temperature between sea-sons or sites, the remaining proportion of the filter paper wasplotted against cumulative soil temperature (Curtin and Fraser2003). Cumulative soil temperature (degree-day) was calcu-lated by summing the average daily soil temperature above0 °C. The data were fitted to a single exponential decayfunction using the least-squares technique in SigmaPlot 11.0(SYSTAT Software Inc., Point Richmond, CA, USA):

Rr ¼ Rie−kt ð2Þ

where R r is the remaining proportion of the filter paper(percent), R i is the initial proportion of the filter paper (i.e.,100 %), k is the decomposition rate constant (degree-day−1),and t is cumulative soil temperature (degree-day). The MRTsfor cellulose in soils were calculated by the reconversion ofunits from degree-day to day (Fierro et al. 2000).

Carbon fluxes from cellulose decomposition and basal soilrespiration

Assuming that soil cellulosic carbohydrates are decomposedby microorganisms at a similar rate to those measured bycellulose tests, the rates of cellulose decomposition can betranslated into the C fluxes to evaluate their magnitude relativeto basal respiration. The C fluxes derived from cellulosedecomposition in a “steady-state” soil can be estimated basedon Eq. 2, using the decomposition rate constant (k ), theconcentrations of soil cellulosic carbohydrates (0–5 cm), andcumulative soil temperature (1 day=10 degree-days for NG,TG, and KT, and 1 day=25 degree-days for RP, DP, and BS).

Basal respiration rates were determined in the laboratory bymeasuring CO2 evolution from field-moist soils (equivalent to10 g DW soil), which were incubated in the dark for 1 h in100 mL Erlenmeyer flasks sealed with silicone rubber septa.Soils were incubated at 10 °C for temperate forests (NG, TG,and KT) and at 25 °C for tropical forests (RP, DP, and BS) at60 % of water holding capacity. The experiments were carriedout in triplicate. Evolved CO2 was collected in glass vialsusing a syringe and measured with an infrared CO2 controller(ZFP9, Fuji Electric Instruments Co., Ltd.) and expressed asmicrograms C per gram per day. The details of the methodwere described in Hayakawa et al. (2011).

Measurement of the cellulose decomposition rateunder laboratory condition

To testify the effects other than climatic factors (temperatureand moisture), the incubation experiments of cellulose filterpaper were conducted under laboratory condition. Cellulosepaper (Advantec no. 6, 22 mm diameter) in nylon mesh bag(mesh pore size, 100 μm) was sandwiched between 15 g (dryweight) of fresh soil material in the 60 mL glass vial and

incubated for 30 days at 25 °C, 60 % of water holdingcapacity. Mass loss of the filter paper after incubation(percent) was measured following the same procedure as thefield incubation.

Calculations and statistics

All data were expressed as mean±standard error (SE) and thecombined SE of three to five replicates (Taylor 1997; Zar1999). Significant differences of the rate constants, k , forcellulose decomposition between sites or seasons were testedatP <0.05 using the F test and the Tukeymethodmodified forcomparison of regression slopes (Zar 1999). Significant dif-ferences in soil cellulose concentrations between sites wereanalyzed at P <0.05 using a one-way ANOVA and multiplecomparisons (Tukey method). A Pearson’s correlation coeffi-cient test was conducted to examine the relationships betweenrate constants and soil properties. The statistical tests wereperformed using Sigmaplot 11.0 (SYSTAT Software Inc., CA,USA).

Results

Physicochemical and microbiological properties of soils

The pH values of TG, KT, and BS soils were lower than theother three sites, consistent with higher concentrations ofexchangeable Al (Table 2). The soil C and N concentrationsin the cool temperate forests (NG and TG) were higher than inthe warmer sites (Table 2). Microbial biomass-C increasedwith soil C and N content (r =0.91, P <0.05 and r =0.92,P <0.05, respectively) and inorganic N content (r =0.88,P <0.05). The relative dominance of fungi in soils increasedwith decreasing pH (r =−0.80, P=0.06).

The total concentrations of hexoses and pentoses present ascellulosic carbohydrates were significantly higher in the NGand TG soils than in other soils (P <0.05; Table 3).Concentrations of total carbohydrates were also significantlyhigher in the NG and TG soils (P <0.05; Table 3). Cellulosicand total carbohydrate-C were positively correlated with SOC(r =0.77, P <0.01 and r =0.94, P <0.01, respectively).Cellulosic- and total carbohydrate-C accounted for 2.5 to5.8 % and 16.4 to 29.4 % of SOC, respectively (Table 3).

Rate constant for cellulose decomposition in soils under fieldcondition

The weight of filter papers decreased during the incubation atall sites, although there was a large variation in mass lossduring the later stages of incubation (Fig. 1). The weight offilter paper decreased by 79 to 95 % at the RPw, DPw, and BSsites within the initial 100 incubation days, while it decreased

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by 22 to 60 % at the NG, TG, and KT sites (Fig. 1). In the dryseasons at RP (RPd) and DP (DPd), the mass loss was evenslower than in the wet seasons despite similar temperatures(Fig. 1b). Within tropical sites during the wet season, theweight of filter paper decreased more slowly at BS than atRPw and DPw (Fig. 1b), despite the higher soil temperature atBS (26 °C).

The proportion of the filter paper remaining was plottedagainst cumulative soil temperature (Fig. 2). The values forthe coefficient of determination (R2) ranged from 0.32 to 0.74,and rate constants (k ) of cellulose decomposition were signif-icant (P <0.01) in all cases except for RPd (Table 4). The kvalues varied widely from 0.9 to 13.3 (×10−4 degree-day−1).The k values at RPw, DPw, and NG were significantly higher,

Table 2 Physicochemical and microbiological properties of the temperate and tropical forest soils

Site TCa

(g kg−1)TNa

(g kg−1)C/N pH Exchangeable Ala

(cmolc kg−1)

Particle size distributionb Inorganic Na, c

(mg N kg−1)Microbial biomassa

(mg C kg−1)Fungal respiratoryactivityd (%)

Sand (%) Silt (%) Clay (%)

Japan (temperate forest)

NG 199 13.4 15 4.4 4.6 25 31 44 490 866 (35) 36

TG 145 8.9 16 4.0 13.0 12 40 49 209 408 (3) 67

KT 77 4.5 17 3.9 8.3 47 25 28 194 196 (2) 71

Thailand (tropical forest)

RP 47 2.6 18 5.0 2.0 5 25 70 207 334 (5) 36

DP 71 4.8 15 4.6 4.1 41 16 43 340 277 (8) 20

Indonesia (tropical forest)

BS 23 1.6 14 4.0 3.9 61 19 20 101 72 (3) 82

The figures in parentheses represent standard errors (n=4)a Oven dry basisb Clay (<0.002 mm); silt (0.002–0.05 mm); sand (0.05–2 mm)c The concentration of inorganic N represents the sum of NH4

+ –N and NO3− –N

dThe data were cited from our recent study (Fujii et al. 2012). The contribution of fungi to total microbial respiration (percent) was calculated using thedifferences between CO2 evolution rates of the glucose-amended soils with/without cycloheximide

Table 3 The amounts of cellulosic and total carbohydrates in the temperate and tropical forest soils

Site Cellulosic carbohydratesa Total carbohydratesa, d (g C kg−1) Percent of TC

Hexoseb (g C kg−1) Pentosec (g C kg−1) Cellulosic-C (%) Total carbohydrate-C (%)

Japan (temperate forest)

NG 4.6 (0.2) b 0.4 (0.1) b 34.4 (0.3) b 2.5 17.3

TG 7.5 (0.2) a 0.8 (0.1) a 36.3 (0.5) a 5.8 25.0

KT 1.6 (0.0) cde 0.3 (0.0) b 14.0 (0.6) c 2.5 17.9

Thailand (tropical forest)

RP 2.2 (0.3) c b.d.l. 13.9 (0.3) c 4.7 29.4

DP 2.1 (0.0) cd b.d.l. 11.6 (0.1) d 3.0 16.4

Indonesia (tropical forest)

BS 1.1 (0.1) e b.d.l. 5.4 (0.1) e 5.0 23.5

The figures in parentheses represent standard errors (n =3). Values followed by the different lowercase letter (a–e) are significantly different between sites

b.d.l . below the detection limita Oven dry basisb Hexoses are calculated on a per C basis, assuming that it was equivalent to the glucose weightc Pentoses are calculated on a per C basis, assuming that it was equivalent to the xylose weightd Total carbohydrates represent the sum of hexoses and pentoses in the first and second hydrolysates (noncellulosic and cellulosic carbohydrates,respectively)

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compared with the other sites (Table 4). Single correlationanalyses between the k values and soil properties (Table 5)were perfoemed. k values increased with increasing soil pH(Fig. 3a) and with decreasing exchangeable Al. No significantrelationship was observed between the k values and fungalrespiratory activity (r =−0.72, P=0.11; Table 5). Based on thek values (Tables 3 and 4), MRTs of cellulose in soils werecalculated to be 81 to 495 days in the temperate forests(Japan), 31 to 61 days in the tropical forests and 658 days indry season (DPd).

Carbon fluxes of cellulose decomposition and basalrespiration in soils

Both the C fluxes of basal respiration and cellulose decompo-sition were highest at NG and RPw within the temperate andtropical forest soils respectively (Table 6). Comparing seasonsat the DP site, the C flux from cellulose decomposition duringthe dry season was lower than the wet season (Table 6). Thelowest C flux from cellulose decomposition was observed atKT. There was a positive correlation between the C fluxes ofcellulose decomposition and basal soil respiration (r =0.90,P <0.001). However, the C fluxes of basal respiration werelower than those from cellulose decomposition in most of thesoils (Table 6).

Cellulose decomposition rates in soils under laboratoryconditions

At the same soil temperature, the mass loss of cellulose filterafter 30-day laboratory incubation varied widely from 0.4 to48.4 % in the temperate forest soils and 16.5 to 51.0 % in thetropical forest soils (Fig. 3b). The mass loss rates of cellulosefilter paper were significantly correlated with soil pH (r =0.89,P <0.05; Fig. 3b). No correlations were found between massloss rates and the other soil properties.

Discussion

Effects of climate on pool sizes of cellulosic and totalcarbohydrates in soils

Assuming that the pool sizes of SOC and soil carbohydratesfluctuate proportionally (Kiem and Kögel-Knabner 2003), thepool sizes of soil cellulosic carbohydrates in tropical forestsare hypothesized to be smaller than in temperate forest soils.Our results showed that the proportion of cellulosic- and totalcarbohydrate-C relative to total SOC varied within a narrowrange (2.5 to 5.8 % and 16.4 to 29.4 % of SOC, respectively(Table 3)). Similar values were reported for other temperateand tropical forests (Folsom et al. 1974; Ishizuka et al. 2006;Martín et al. 2009; Nacro et al. 2005; Zinn et al. 2002). In

Incubation period (day)

Rem

aini

ng p

ropo

rtio

n of

cel

lulo

se p

aper

(%

)

RPw

RPd

DPw

DPd

BS

NG

TG

KT

0

20

40

60

80

1000

20

40

60

80

100

0 100 200 30050 150 250

Japan

Thailand

Indonesia

a

b

Fig. 1 Remaining proportion of cellulose paper (filter paper) during thefield incubation period in the temperate (a) and tropical forest soils (b).The symbols denote experimental data points. Bars indicate standarderrors (n =5). The subscripts of RP and DP (Thailand) indicate samplingperiods: w wet season, d dry season

50000 1000 2000 3000 40000

20

40

60

80

1000

20

40

60

80

100

Cumulative soil temperature (degree-days)

Rem

aini

ng p

ropo

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n of

cel

lulo

se p

aper

(%

)

RPw

RPd

DPw

DPd

BS

NG

TG

KT

Japan

Thailand

Indonesia

a

b

Fig. 2 The remaining proportion of cellulose paper (filter paper) plottedagainst cumulative soil temperature during the field incubation in thetemperate (a) and tropical forest soils (b). Symbols denote experimentaldata points, whereas the lines represent fits to a single exponential decayfunction. Bars indicate standard errors (n =5). The subscripts ofRP and DP (Thailand) indicate the sampling periods: w wetseason, d is dry season

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proportion to SOC, the concentrations of cellulosic- and totalcarohydrate-C were lower in the tropical forests (RP, DP, andBS) than in the cool temperate forests at NG and TG (Table 3).This is considered to result from the rapid decomposition ofOM in warmer climate (Nacro et al. 2005; Navarrete andTsutsuki 2008). Among the tropical forests, the concentrationsof soil carbohydrates at RP and DP were higher than at BS(Table 3). This may be related to the slower decomposition ofcellulose in dry seasons of RP and DP (Figs. 1 and 2).

Effects of temperature on the rate of cellulose decompositionin soils

The activity of soil microorganisms to decompose SOM gen-erally increases with temperature and moisture, as describedby soil C models (Jenkinson et al. 1990; Parton et al. 1987).Similarly, production of cellulases and their decompositionactivity can be enhanced by high temperature and moisture(Deng and Tabatabai 1994; Trasar-Cepeda et al. 2007). In ourstudy, the higher rates of cellulose decomposition in the trop-ical forests indicated that cellulolytic activity is primarilydependent on soil temperature (Fig. 1). Regarding the effectsof soil moisture on decomposition rates, the k values ofcellulose decomposition in dry seasons at RP and DP werelower than those of wet seasons (Fig. 1b; Table 4). Thisindicated that the dry season can limit the decomposition rates(Table 4). However, no correlation was found between soilmoisture and the k values of cellulose decomposition(Table 4). This suggests that cellulolytic activity is stronglydependent on temperature rather than water availabilityamong the forest soils under humid condition.

Even after conversion of x-axis from time (day) to cumula-tive soil temperature (degree-day), the rate constants of cellu-lose decomposition differed between sites (Fig. 2). The widevariation of k values related to the cumulative soil temperaturesuggests that the rates of cellulose decomposition are not

Table 4 Rate constants (k) of cellulose decomposition, mean residence times (MRTs) of cellulose and mean soil temperature and water content duringfield incubation

Sitea Rate constant (k) (10−4 degree-day−1) R2 MRTb (days) Soil temperaturec (°C) Soil water content (%) pFd

Japan (temperate forest)

NG 8.8 (0.8) ab 0.69*** 81 14.1 53 2.1

TG 2.7 (0.4) cd 0.47*** 232 16.0 44 1.3

KT 1.0 (0.1) de 0.32*** 495 15.4 33 2.0

Thailand (tropical forest)

RPw 13.3 (0.8) a 0.74*** 31 24.4 39 2.4

RPd n.d. n.d. n.d. 21.2 24 4.5

DPw 9.4 (0.6) ab 0.72*** 55 19.4 39 2.5

DPd 0.9 (0.1) e 0.32*** 658 18.5 29 4.1

Indonesia (tropical forest)

BS 6.4 (0.5) bc 0.46*** 61 25.6 27 2.2

The figures in parentheses represent standard errors of regression coefficients (k).The significant difference in rate constants among the sites is indicatedby different letters (P <0.05)

n.d . not determined

***P<0.001a The subscripts of RP and DP indicate the sampling periods: wet season (w) and dry season (d)b The degree-day was reconverted to day using degrees per day (14.1–25.6 °C day−1 )cMean soil temperature of DP site was estimated using air temperature (2004–2005, NCDC) and the data of soil temperature and air temperaturemonitored in DP (Funakawa et al. 2006)d pF values are calculated using the mean soil water content and water retention curves of the soils

Table 5 Correlations between the rate constant (temperature normalized)of cellulose decomposition and soil properties

Correlation coefficient

Mean soil water content 0.21

Clay content 0.63

Soil pH 0.94***

Exchangeable Al −0.83*Fungal respiratory activity −0.72TC −0.16C/N ratio −0.19Inorganic N 0.31

Microbial biomass-C 0.24

*P<0.05; ***P <0.001

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simply dependent on temperature (Table 4). The decomposi-tion rates appeared to vary depending on soil properties andclimatic factors, within the temperate and tropical forests(Table 4). Although the effects of clay content on mineraliza-tion of monomers are well-known (Sorensen 1975), our find-ings suggest that depolymerization rates are dependent on soilproperties as well as temperature, as also reported by Allisonet al. (2010) and Elmajdoub and Marschner (2013).

Effects of pH and the other soil properties on rates of cellulosedecomposition in soils

Soil acidity is one important factor regulating cellulose de-composition rates, as it controls the abundance of fungi andactivity of extracellular enzymes (Deng and Tabatabai 1994;Kemmitt et al. 2006). The rate constants of cellulose decom-position are lower in highly acidic soils of both temperate andtropical forests (Table 4; Fig. 3a). The restricted decomposi-tion of cellulose at low pH (Fig. 3a) was also supported by theresults of the laboratory incubation (Fig. 3b) and previousstudies (Bieńkowski 1990; Hopkins et al. 1990). This can beexplained by (1) the decreased cellulase activity at pH <5.5(optimal pH) (Criquet 2002; Deng and Tabatabai 1994; Hopeand Burns 1987) and (2) the increased Al toxicity to microor-ganisms (Illmer and Mutschlechner 2004; Piña and Cervantes1996) and deactivation of enzymes by Al (Miltner and Zech1998; Scheel et al. 2008).

Regarding the above point (1), fungi can generally producegreater amounts of cellulases (Lynd et al. 2002) and theydegrade cellulose more rapidly compared with bacteria(Waksman and Skinner 1926). Although fungi predominatein the highly acidic soils at TG, KT, and BS (Table 2), cellu-lase activity sharply decreased as pH decreased from 5.5 to 4.0(Criquet et al. 2002; Deng and Tabatabai 1994; Hope andBurns 1987). In our study, low soil pH, rather than fungalactivity, may have reduced cellulose decomposition througheffects on cellulase activity. Cellulose tests revealed that inaddition to temperature, soil pH could be one of the rate-regulating factors of cellulose decomposition across temperateand tropical forests of humid Asia. However, it should benoted that pH is an index parameter varying concurrently withthe other soil properties. In our study, this might mask theeffects of other possible rate-regulating factors reported by theother studies (availability of N, P, and labile C (Kemmitt et al.2006), salinity (Setia and Marschner 2013), and stimulation/inhibition effects of flavonoids (Cesco et al. 2012)). Furtherverification is needed under controlled conditions.

Carbon fluxes from cellulose decomposition and theirimplication for soil carbon cycles

The field experiments of cellulose decomposition can beapplied for estimating the C fluxes of cellulose

a

b

Fig. 3 Relationships between soil pH and (a) the rate constants (temper-ature normalized) of cellulose decomposition (k) during the field incuba-tion and (b) the loss of cellulose filter paper (percent) after the 30-daylaboratory incubation. Bars indicate standard errors of regression coeffi-cients and loss of filter paper

Table 6 Basal respiration and cellulose decomposition rates in the tem-perate (10 °C) and tropical (25 °C) forest soils

Site Cellulose decompositiona

(μg C g−1 day−1)Basal respiration(μg C g−1 day−1)

Japan (temperate forest)

NG 44 (2) 21 (4)

TG 23 (1) 15 (0)

KT 2 (0) 12 (2)

Thailand (tropical forest)

RPw 73 (9) 22 (1)

RPd n.d. n.d.

DPw 49 (1) 17 (2)

DPd 4 (0) n.d.

Indonesia (tropical forest)

BS 18 (1) 11 (1)

The figures in parentheses represent standard errors

n.d . not determineda Cellulose decomposition rate was estimated under the same temperaturecondition as basal respiration, based on the amount of soil cellulose(Table 3) and the rate constant of filter decomposition (Table 4)

640 Biol Fertil Soils (2014) 50:633–643

decomposition, as well as measuring cellulolytic activity(Drewnik 2006; Sparrow et al. 1992). Respiratory C fluxescaused by cellulose decomposition can be estimated usingdata of cellulose decomposition rates (Table 4) and the poolsize of soil cellulosic carbohydrates (Table 3). The estimatedsoil C fluxes suggest that the rates of cellulose decompositionand basal respiration varied widely within the temperate andtropical forests, respectively (Table 6). The high C fluxes fromcellulose decomposition at NG and RPwwere considered to becaused by higher cellulose concentrations and cellulolyticactivities (Tables 3 and 4). The lower rate of cellulose decom-position at BS, despite the higher cellulolytic activity than atTG (Tables 4 and 6), suggests that the C flux of decompositioncan also be limited by substrate availability in a tropical humidclimate (Table 3).

The positive correlation between basal respiration and cel-lulose decomposition (Fig. 4) highlights the importance ofcarbohydrates as substrates for basal (heterotrophic) soil res-piration. The MRTs of monosaccharides were consistentlyshort (0.4 to 1.5 h) at all sites according to our recent study(Hayakawa et al. 2011), whereas the MRTs of cellulose variedfrom 31 to 658 days (Table 4). These data are consistent withthe importance of depolymerization as a rate-limiting step indecomposition of polymeric SOM (Allison et al. 2010). Inaddition to temperature and moisture, the C fluxes from cel-lulose decomposition varied from soil to soil, depending onacidity and substrate availability (Table 4; Fig. 1). Consideringthat the C fluxes from cellulose decomposition could consti-tute a dominant fraction of basal respiration (Table 6;Hayakawa et al. 2011), the rate-regulating factors of cellulosedecomposition may accordingly influence the rates of hetero-trophic soil respiration.

The C fluxes of basal respiration were lower than thosefrom cellulose decomposition (Table 6). This suggests thatcellulosic carbohydrates are decomposed at the slower rates inthe actual soil C cycles than found in the cellulose paperincubation. This could be explained by the following reasons:(1) a large proportions of soil cellulosic carbohydrates aremicrobially synthesized and are not simple compared withcellulose filter paper, and (2) they are present in a morerecalcitrant form due to complexation with aromatic com-pounds or protection by aggregation (Kiem and Kögel-Knabner 2003). The higher rates of basal soil respiration,compared with cellulose decomposition, at KT (Table 6)may be attributed to the mineralization of SOM other thancarbohydrates. This is partly confirmed by our observation atKT, where in large fluxes of organic acids and aromaticcompounds can be produced from root/microbial exudatesand lignin solubilization (Cesco et al. 2012; Fujii et al. 2010,2012).

Analysis of MRTs and C fluxes of cellulose decompositionshowed that soil pH can influence the rates of organic matterdecomposition, in addition to the climatic factors such as

temperature, moisture, and substrate availability. The rate-regulating factors of depolymerization of polymeric SOM,i.e., soil pH and temperature, may accordingly influence therates of heterotrophic soil respiration. Although the effects ofthe other properties (N and P availability, lignin protection,flavonoids) on microbial activity and the degradation of SOMremains to be studied (Chaparro et al. 2012), our study indi-cated that soil pH can be one of the important factors causingthe local variation of the C fluxes of heterotrophic respirationwithin the temperate and tropical forests of humid Asia.

Conclusions

Rates of cellulose decomposition increased with soil tempera-ture, except for during the dry season. The estimated MRTs ofsoil cellulosic carbohydrates varied from 81 to 495 days withintemperate forests and 31 to 61 days within tropical forests. Therates of cellulose decomposition decreased with decreasing soilpHwithin the temperate and tropical forests. The C fluxes fromcellulose decomposition can account for a substantial fractionof heterotrophic soil respiration. Heterotrophic respiration ratesincreased with cellulose decomposition, which is regulated bytemperature, soil pH, and substrate availability. Our studysuggested that the rate-regulating factors of depolymerizationof polymeric SOM, i.e., soil pH and temperature, may accord-ingly influence the rates of heterotrophic soil respiration.Further research is needed to analyze the direct/indirect effectsof pH and the other soil properties (N and P) on the decompo-sition of cellulose and the other organic constituents of SOM.The effects of labile C addition on SOM decomposition rates,including priming effects (Fontaine et al. 2007), need to bequantitatively evaluated relative to basal respiration, alongwith analyses of microbial community composition or en-zymes at a molecular level (Nannipieri et al. 2012; Rascheand Cadish 2013).

Acknowledgments The authors thank Yatsugatake Experimental For-est of Tsukuba University, Forestry and Fisheries of Japan, YoshidaShrine, Tropical Rainforest Research Center, Mulawarman Universityand the villagers in Ban Rakpaendin and Ban Du La Poe, Thailand forallowing us to conduct our experiments. We also thank Dr. Sean Case(University of Copenhagen) for valuable discussions and proofreading,and the editor and two anonymous reviewers for their helpful suggestionsand comments on the manuscript.

References

Allison SD, Wallenstein MD, Bradford MA (2010) Soil-carbon responseto warming dependent on microbial physiology. Nat Geosci 3:336–340. doi:10.1038/NGEO846

Anderson JPE, Domesch KH (1978) A physiological method for thequantitative measurement of microbial biomass in soils. Soil BiolBiochem 10:215–221. doi:10.1016/0038-0717(78)90099-8

Biol Fertil Soils (2014) 50:633–643 641

Berg B, McClaugherty C (2003) Decomposition as a process. In: Berg B,McClaugherty C (eds) Plant litter-decomposition, humus formation,carbon sequestration. Springer, Berlin, pp 11–30

Beyer L (1992) Cellulolytic activity of luvisols and podzols under forestand arable land using the “cellulose-test” according to Unger.Pedobiologia 36:137–145

Bieńkowski P (1990) Cellulose decomposition as bioenergetic indicatorof soil degradation. Pol Ecol Stud 16:235–244

Cesco S, Mimmo T, Tonon G, Tomasi N, Pinton R, Terzano R, NeumannG, Weisskopf L, Renella G, Landi L, Nannipieri P (2012) Plant-borne flavonoids released into the rhizosphere: impact on soil bio-activities related to plant nutrition. A review. Biol Fertil Soils 48:123–149. doi:10.1007/s00374-011-0653-2

Chaparro JM, Shelfin AM,Manter DK, Vivanco JM (2012)Manipulatingthe soil microbiome to increase soil health and plant fertility. BiolFertil Soils 48:489–499. doi:10.1007/s00374-012-0691-4

Cheshire MV (1979) Nature and origin of carbohydrates in soils.Academic, London

Criquet S (2002) Measurement and characterization of cellulase activityin sclerophyllous forest litter. J Microbiol Meth 50:165–173. doi:10.1016/S0167-7012(02)00028-3

Criquet S, Tagger S, Vogt G, Le Petit J (2002) Endoglucanase and β-glycosidase activities in an evergreen oak litter: annual variation andregulating factors. Soil Biol Biochem 34:1111–1120. doi:10.1016/S0038-0717(02)00045-7

Curtin D, Fraser PM (2003) Soil organic matter as influenced by strawmanagement practices and inclusion of grass and clover seed cropsin cereal rotations. Aust J Soil Res 41:95–106. doi:10.1071/SR01103

Deng SP, Tabatabai MA (1994) Cellulase activity of soils. Soil BiolBiochem 26:1347–1354. doi:10.1016/0038-0717(94)90216-X

Drewnik M (2006) The effect of environmental conditions on the decom-position rate of cellulose in mountain soils. Geoderma 132:116–130.doi:10.1016/j.geoderma.2005.04.023

Elmajdoub B, Marschner P (2013) Salinity reduces the ability of soilmicrobes to utilize cellulose. Biol Fertil Soils 49:379–386. doi:10.1007/s00374-012-0734-x

Fierro A, Angers DA, Beauchamp CJ (2000) Decomposition of paper de-inking sludge in a sandpit minesoil during its revegetation. Soil BiolBiochem 32:143–150. doi:10.1016/S0038-0717(99)00123-6

Folsom BL, Wager GH, Scrivner CL (1974) Comparison of soil carbo-hydrate in several prairie and forest soils by gas–liquid chromatog-raphy. Soil Sci Soc Am Proc 38:305–309. doi:10.2136/sssaj1974.03615995003800020027x

Fontaine S, Barot S, Barré P, Bdioui N, Mary B, Rumpe C (2007)Stability of organic carbon in deep soil layers controlled by freshcarbon supply. Nature 450:277–281. doi:10.1038/nature06275

Fujii K, Funakawa S, Hayakawa C, Kosaki T (2008) Contribution ofdifferent proton sources to pedogenetic soil acidification in forestedecosystems in Japan. Geoderma 144:478–490. doi:10.1016/j.geoderma.2008.01.001

Fujii K, Funakawa S, Hayakawa C, Sukartingsih KT (2009)Quantification of proton budgets in soils of cropland and adjacentforest in Thailand and Indonesia. Plant Soil 316:241–255. doi:10.1007/211104-008-9776-0

Fujii K, Hayakawa C, Van Hees PAW, Funakawa S, Kosaki T (2010)Biodegradation of low molecular weight organic compounds andtheir contribution to heterotrophic soil respiration in threeJapanese forest soils. Plant Soil 334:475–489. doi:10.1007/s11104-010-0398-y

Fujii K, Uemura M, Hayakawa C, Funakawa S, Kosaki T (2012)Environmental control of lignin peroxidase, manganese peroxidase,and laccase activities in forest floor layers in humid Asia. Soil BiolBiochem 57:109–115. doi:10.1016/j.soilbio.2012.07.007

Fukui S (1990) Analytical methods of reduced sugar, 2nd. JapanScientific Societies, Tokyo (in Japanese)

Funakawa S, Tanaka S, Kaewkhongkha T, Hattori T, Yonebayashi K(1997) Physicochemical properties of the soils associated withshifting cultivation in Northern Thailand with special reference tofactors determining soil fertility. Soil Sci Plant Nutr 43:665–679.doi:10.1080/00380768.1997.10414792

Funakawa S, Hayashi Y, Tazaki I, Kozue S, Kosaki T (2006) The mainfunctions of the fallow phase in shifting cultivation by Karen peoplein northern Thailand—a quantitative analysis of soil organic matterdynamics. Tropics 15:1–27

Gee GW, Bouder JW (1986) Particle-size analysis. In: Klute A (ed)Methods of soil analysis Part1 physical and mineralogical methods,2nd edn. American Society of Agronomy Inc., Soil Science Societyof America Inc, Madison, pp 383–411

Hayakawa C, Fujii K, Funakawa S, Kosaki T (2011) Biodegradationkinetics of monosaccharides and their contribution to basal respira-tion in tropical forest soils. Soil Sci Plant Nutr 57:663–673. doi:10.1080/00380768.2011.623226

Hope CFA, Burns RG (1987) Activity, origins and location of cellulasesin a silt loam soil. Biol Fertil Soils 5:164–170. doi:10.1007/BF00257653

Hopkins DW, Ibrahim DM, O' Donell AG, Shiel RS (1990)Decomposition of cellulose, soil organic matter and plant litter in atemperate grassland soil. Plant Soil 124:79–85. doi:10.1007/BF00010934

Hsu PH (1963) Effect of initial pH, phosphate and silicate on the deter-mination of aluminium with aluminum. Soil Sci 96:230–238

Illmer P, Mutschlechner W (2004) Effect of temperature and pH on thetoxicity of alminium towards two new, soil born species ofArthrobacter sp. J Basic Microbiol 44:98–105. doi:10.1002/jobm.200310293

Ishizuka S, Sakata T, Sawata S, Ikeda S, Takenaka C, Tamai N, Sakai H,Shimizu T, Kan-Na K, Onodera S, Tanaka N, Takahashi M (2006)High potential for increase in CO2 flux from forest soil surface dueto global warming in cooler areas of Japan. Ann For Sci 63:537–546. doi:10.1051/forest:2006036

Jenkinson DS, Andrew SPS, Lynch JM, Goss MJ, Tinker PB (1990) Theturnover of organic carbon and nitrogen in soil [and discussion]. PhilTrans R Soc Lond B-329:361–368. doi:10.1098/rstb.1990.0177

Joergensen RG, Wichern F (2008) Quantitative assessment of the fungalcontribution to microbial tissue in soil. Soil Biol Biochem 40:2977–2991. doi:10.1016/j.soilbio.2008.08.017

Kemmitt SJ, Wright D, Goulding KWT, Jones DL (2006) pH regulationof carbon and nitrogen dynamics in two agricultural soils. Soil BiolBiochem 38:898–911. doi:10.1016/j.soilbio.2005.08.006

Kiem R, Kögel-Knabner I (2003) Contribution of lignin and polysaccha-rides to the refractory carbon pool in C-depleted arable soils. SoilBiol Biochem 35:101–118. doi:10.1016/S0038-0717(02)00242-0

Kim C (2010) Cellulose decomposition rates in clear-cut and uncut redpine (Pinus densiflora S. et Z.) stands. For Sci Tech 6:29–34. doi:10.1016/j.foreco.2008.02.012

Landi L, Badalucco L, Pomarě F, Nannipieri P (1993) Effectiveness ofantibiotics to distinguish the contributions of fungi and bacteria tonet nitrogen mineralization, nitrification and respiration. Soil BiolBiochem 25:1771–1778. doi:10.1016/0038-0717(93)90182-B

Lynd LR, Weimer PJ, Van Zyl WH, Pretorius IS (2002) Microbialcellulose utilization: fundamentals and biotechnology.Microbiol Mol Biol Rev 66:506–577. doi:10.1128/MMBR.66.3.506-577.2002

Martín A, Díaz-Raviña M, Carballas T (2009) Evolution of compositionand content of soil carbohydrates following forest wildfires. BiolFertil Soils 45:511–520. doi:10.1007/s00374-009-0363-1

Miltner A, Zech W (1998) Carbohydrate decomposition in beech litter asinfluenced by aluminium, iron and manganese oxides. Soil BiolBiochem 30:1–7. doi:10.1016/S0038-0717(97)00092-8

Mulvaney RL (1996) Nitrogen-inorganic forms. In: Sparks DL (ed)Methods of soil analysis Part3 Chemical methods. Soil Science

642 Biol Fertil Soils (2014) 50:633–643

Society of America, Americal Society of Agronomy, Madison, pp1123–1184

Nacro HB, Larré-Larrouy MC, Feller C, Abbadie L (2005) Hydrolysablecarbohydrate in tropical soils under adjacent forest and savannavegetation in Lamto, Côte d'Ivoire. Aust J Soil Res 43:705–711.doi:10.1071/SR03134

Nannipieri P, Giagnoni L, Renella G, Puglisi E, Ceccanti B, MasciandaroG, Fornasier F, Moscatelli MC, Marinari S (2012) Soil enzymology:classical and molecular approaches. Biol Fertil Soils 48:743–762.doi:10.1007/s00374-012-0723-0

Navarrete IA, Tsutsuki K (2008) Land use impact on soil carbon, nitro-gen, natural sugar composition and related chemical properties in adegraded Ultisol in Leyte, Philippines. Soil Sci Plant Nutr 54:321–331. doi:10.1111/j.1747-0765.2008.00244.x

Oades JM, Kirkman MA, Wagner GH (1970) The use of gas–liquidchromatography for the determination of sugars extracted from soilsby sulfuric acid. Soil Sci Soc Am Proc 34:230–235. doi:10.2136/sssaj1970.03615995003400020017x

Parton WJ, Schimel DS, Cole CV, Ojima DS (1987) Soil microbiologyand biochemistry analysis of factors controlling soil organic matterlevels in Great Plains grasslands. Soil Sci Soc Am J 51:1173–1179.doi:10.2136/sssaj1987.03615995005100050015x

Paul EA, Clark FE (1996) Carbon cycling and soil organic matter. In:Paul EA, Clark FE (eds) Soil microbiology and biochemistry.Academic Press, San Diego, pp 129–155

Piña RG, Cervantes C (1996) Microbial interactions with aluminium.Biometals 9:311–316. doi:10.1007/BF00817932

Qualls RG (2000) Comparison of the behavior of soluble organic andinorganic nutrients in forest soils. For Ecol Manag 138:29–50. doi:10.1016/S0378-1127(00)00410-2

Rasche F, Cadish G (2013) The molecular microbial perspective oforganic matter turnover and nutrient cycling in tropicalagroecosystems-What do we know? Biol Fertil Soils 49:251–262.doi:10.1007/s00374-013-0775-9

Rhine ED, Sims GK, Mulvaney RL, Pratt EJ (1998) Improving theBerthelot reaction for determining ammonium in soil extracts andwater. Soil Sci Soc Am J 62:473–480. doi:10.2136/sssaj1998.03615995006200020026x

Scheel T, Jansen B, Van Wijk AJ, Verstraten JM, Kalbits K (2008)Stabilization of dissolved organic matter by aluminium: a toxiceffect or stabilization through precipitation? Eur J Soil Sci 59:1122–1132. doi:10.1111/j.1365-2389.2008.01074.x

Schneckenberger K, Demin D, Stahr K, Kuzyakov Y (2008) Microbialutilization and mineralization of [14C] glucose added in six orders ofconcentration to soil. Soil Biol Biochem 40:1981–1988. doi:10.1016/j.soilbio.2008.02.020

Setia R, Marschner P (2013) Carbon mineralization in saline soils asaffected by residue composition andwater potential. Biol Fertil Soils49:71–77. doi:10.1007/s00374-012-0698-x

Shirato Y, Hakamata T, Taniyama I (2004) Modified rothamstedcarbon model for andosols and its validation: changing humusdecomposition rate constant with pyrophosphate-extractable Al.Soil Sci Plant Nutr 50:149–158. doi:10.1080/00380768.2004.10408463

Soil Survey Staff (2006) Keys to Soil Taxonomy, 10th edn. United StatesDepartment of Agriculture Natural Resources Conservation Service,Washington

Sorensen LH (1975) The influence of clay on the rate of decay on aminoacid metabolites synthesized in soils during decomposition of cellu-lose. Soil Biol Biochem 7:171–177. doi:10.1016/0038-0717(75)90015-2

Sparrow SD, Sparrow EB, Cochran VI (1992) Decomposition in forestand fallow subarctic soils. Biol Fertil Soils 14:253–259. doi:10.1007/BF00395460

Stevenson FJ (1982) Soil carbohydrates. In: Stevenson FJ (ed) Humuschemistry-genesis, composition, reactions. John Wiley & Sons,New York, pp 146–171

Taylor JR (1997) An introduction to error analysis: the study of uncer-tainties in physical measurements, 2nd edn. University ScienceBooks, California

Trasar-Cepeda C, Gil-Sotres F, Leirós MC (2007) Thermodynamic pa-rameters of enzymes in grassland soils fromGalicia, NWSpain. SoilBiol Biochem 39:311–319. doi:10.1016/j.soilbio.2006.08.002

Van Hees PAW, Johansson E, Jones DL (2008) Dynamics of simplecarbon compounds in two forest soils as revealed by soil solutionconcentrations and biodegradation kinetics. Plant Soil 30:11–23.doi:10.1007/s11104-008-9263-3

Waksman SA, Skinner CE (1926) Microorganisms concerned in thedecomposition of celluloses in the soil. J Bacteriol 12:57–84

Withington CL, Stanford RL Jr (2007) Decomposition rates of buriedsubstrates increase with altitude in the forest-alpine tundra eco-tone. Soil Biol Biochem 39:68–75. doi:10.1016/j.soilbio.2006.06.011

Zar JH (1999) Biostatistical analysis, 4th edn. Prentice-Hall, New JerseyZinn YJ, Resck DVS, da Silva JE (2002) Soil organic carbon as affected

by afforestation with Eucalyptus and Pinus in the Cerrado region ofBrazil. For Ecol Manag 166:285–294. doi:10.1016/S0378-1127(01)00682-X

Zunino H, Borie F, Aguilera S, Martin JP, Haider K (1982)Decomposition of 14C-labeled glucose, plant andmicrobial productsand phenols in volcanic ash-derived soils of Chile. Soil BiolBiochem 14:37–43. doi:10.1016/0038-0717(82)90074-8

Biol Fertil Soils (2014) 50:633–643 643