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t 255 (2008) 2244–2250

Forest Ecology and Managemen

A new instrument for measurement and collection of quantitative

samples of the litter layer in forests

Ben Hur Marimon-Junior 1, John D. Hay *

Departamento de Ecologia, Universidade de Brasılia, Campus Universitario Darcy Ribeiro, 70.910-900 Brasılia, DF, Brazil

Received 10 May 2007; received in revised form 20 December 2007; accepted 1 January 2008

Abstract

The litter layer plays an important role in the maintenance of tropical forests. The evaluation of parameters such as thickness or water content

can reveal forest conditions that are of global relevance (for example carbon stock) or of local importance such as the conservation of nutrients in

native forests or plantations. However, there is no specific instrument or protocol for quantitative collection of the litter layer. We developed an

instrument composed of two parts that permits measurement and collection of the litter layer, following a simple protocol. The method was tested in

two forest types and we verified the greater accuracy and ease of use of the instrument compared to two other commonly used litter collection

methods.

# 2008 Elsevier B.V. All rights reserved.

Keywords: Litter thickness; Nutrient cycling; Brazil

1. Introduction

The litter layer plays a fundamental role in the maintenance

of tropical forests (Vitousek, 1982; Jordan, 1985; Vitousek and

Sanford, 1986; Cuevas and Medina, 1988) impeding the loss of

nutrients due to the strong weathering in the tropics (Herrera

et al., 1978; Stark and Jordan, 1978; Jordan and Escalante,

1980; Jordan and Herrera, 1981) and acting in the maintenance

of the chemical and physical properties of the soil that are

important for the equilibrium and sustainability of the

vegetation (Nill and Nill, 1993; Park et al., 1998; Gonzales-

Sosa et al., 1999; Swift and Bignell, 2000; Lavelle et al., 2001;

Lavelle and Spain, 2002; Hairiah et al., 2006). The quantitative

measurement of the parameters of the litter layer is a powerful

tool for the determination of diverse ecological conditions that

are of relevant interest in a world context of tropical forests

(Sampaio et al., 1993; Tapia-Coral et al., 2005). The physical

and chemical properties and biological of the litter layer are

important as indicators of local conditions in forest plantations

such as nutrient stock (Smith et al., 1998; Cunha et al., 2005),

* Corresponding author. Tel.: +55 61 3307 2592.

E-mail address: jhay@unb.br (J.D. Hay).1 Present address: Departamento de Ciencias Biologicas, Universidade do

Estado de Mato Grosso, UNEMAT, Rod. BR 158 km 145, 78690-000 Nova

Xavantina, MT, Brazil.

0378-1127/$ – see front matter # 2008 Elsevier B.V. All rights reserved.

doi:10.1016/j.foreco.2008.01.037

soil humidity (Marimon-Junior, 2007) or in the formation of

organic matter, all important aspects in evaluation of forest

conditions, especially in degraded areas undergoing regenera-

tion (Souza and Davide, 2001).

The thickness of the litter layer is a reflection of the balance

between the inputs and decomposition of organic matter and

can be an excellent indicator of the diverse conditions of

maintenance and equilibrium in forests (Vorobeichik, 1997).

Litter also has a strong influence on the soil profile, especially

the A horizon, protecting it against destruction of soil

aggregates and sealing the pores in regard to water infiltration

(Nill and Nill, 1993) nutrient loss due to leaching (Hairiah et al.,

2006) and loss of water vapor by evaporation due to the direct

incidence of solar radiation on the soil surface (Park et al.,

1998; Gonzales-Sosa et al., 1999). Another important benefit of

the litter layer is through the redistribution of organic matter

due to the action of soil arthropods (Swift and Bignell, 2000).

In spite of the importance of the evaluation of these aspects

and the increase of interest in forest monitoring there is no

specific instrument for quantitative measurement and collection

of samples of the litter layer. Besides the lack of an adequate

collection instrument there is also a lack of a standardized

collection methodology or protocol. Studies of the litter layer in

Brazil and other countries are still based on rudimentary

methods for the measurement of the thickness of the litter layer

and sample collection. These included collection of leaves with

Fig. 1. Photograph of the Marimon–Hay litter collector showing: (A) base,

formed by a base of multiple tines used to collect the litter from the forest floor

and (B) measuring fork. The ruler is graduated in cm. The collection device

shown has 42 tines.

B.H. Marimon-Junior, J.D. Hay / Forest Ecology and Management 255 (2008) 2244–2250 2245

a spike (Molofsky and Augspurger, 1992; Torti et al., 2001),

also called a litter probe (Mayor and Henkel, 2006), or by

estimates of depth with a ruler (Muscolo et al., 2007; Roovers,

2005; Portela and Santos, 2007).

In order to resolve this problem, we designed and

constructed an instrument for the measurement of the thickness

of the litter layer and quantitative collection of litter samples in

forests. We compared our instrument with the two traditional

litter collection methods cited above.

2. Materials and methods

2.1. Study area

Collection was done in two areas of native forest on the Vera

Cruz farm (property of Jairo Machado Rezende) in the

municipality of Nova Xavantina, eastern Mato Grosso, Brazil.

The first area was a monodominant forest (1485004700S latitude

and 5280803700W longitude), with Brosimum rubescens Taub.

accounting for over 80% of the above-ground biomass

(Marimon, 2005). The other forest area (1484903200S latitude

and 5280602000W longitude) was a mixed species forest where

B. rubescens was rare. Both forest areas are on flat terrain and

the annual litter input in both forests was similar, approximately

7.75 t/ha (Marimon-Junior, 2007). This region is a pre-

Amazonian transitional forest, with contact with the cerrado.

The climate is tropical with well-defined rainy and dry seasons.

The mean annual precipitation is 1500 mm and mean

temperature is 24.8 8C, with a mean minimum temperature

of 10 8C and a mean maximum of 37.4 8C. The soil is a

Plintosoil in the Brazilian soil classification system

(EMBRAPA, 1999), aeolic and concretionary with low cation

exchange capacity, base saturation and water retention, and has

a continuous lateritic layer at 80 cm depth. All data were

collected in previously established plots in each forest type (for

a detailed description of the sites see Marimon et al., 2001;

Marimon, 2005).

2.2. Description of the Marimon–Hay litter collector

The new instrument tested in the present study is called the

Marimon–Hay litter collector or multiple tine collector,

hereafter referred to as M–H. It is composed of two pieces,

a base and a fork that intersect (Fig. 1). The base is used in the

collection of the litter on the forest floor and the fork is used to

measure the thickness. The collector design was discussed and

developed in the ecology laboratories of the University of

Brasilia and the State University of the State of Mato Grosso

during 2 years and was patented in Brazil (Fundacao

Universidade de Brasılia, 2005). The base of the collector

measures 15 cm � 12.5 cm (187.5 cm2) and may have 35 or 42

tines (approximately 15 cm in length). The fork has seven teeth

for the 42 tine collector and six for the 35 tine collector. Both

pieces are made of steel and the tines are welded onto the base.

The handles of the base and the fork are covered with molded

rubber padding. The total weight of the instrument is

approximately 0.9 kg.

2.3. Sample collection protocol

The collection protocol is composed of two steps. The first in

the field and the second in the laboratory, if determination of

water content or nutrient content of the litter is desired. In the

field, the following sequence should be followed:

(1) L

ocalization of the sampling point, based on the area of the

collector a minimum of 30 points/ha should be collected.

(2) C

ollection (Fig. 2A) and removal of the litter sample from

the forest floor.

(3) V

isual verification of the sampled point (Fig. 2B). This

verification is important to confirm that when the sample is

lifted off the forest floor the root mat should be exposed,

indicating that the sample corresponds only to the L and F

layers leaving the H layer intact, following the division of

Hoover and Lunt (1952). The H layer should not be

removed since it contains a mixture of mineral soil and

other material. If part of the H layer or part of the root mat is

removed the sample should be discarded and the procedure

repeated at another point.

(4) M

easurement of the thickness of the sample. Insert the fork

between the tines and lift it until it touches, without

compressing the base of the collected material. Read the

thickness of the litter layer on the ruler (Fig. 2C).

(5) I

f litter samples are also being collected for determination

of moisture or nutrient content the following procedure

should be followed. After measurement of the thickness of

the litter layer the sample should be firmly compressed

against the base of the collector using the fork. Any excess

material that extends beyond the sides of the collector

should be trimmed with scissors or pruning shears (Fig. 2D)

and discarded and the remaining litter on the base should be

Fig. 2. Collection and measurement of litter with the M–H collector in the field, showing: (A) sample collection; (B) visual verification of the sample site; (C)

measurement of the thickness of the litter on the included scale; (D) removal of excess material to obtain a quantitative sample. Data collected on the Vera Cruz farm,

Nova Xavantina, Mato Grosso, Brazil.

B.H. Marimon-Junior, J.D. Hay / Forest Ecology and Management 255 (2008) 2244–22502246

removed and placed in a previously tared recipient that can

be sealed to prevent water vapor loss.

In the laboratory, the protocol should follow the following

steps:

(1) U

sing an analytical or semi-analytical balance weigh each

sample to obtain its fresh weight.

(2) D

ry the samples in a forced draft oven until constant weight

(minimum of 48 h at 70 8C).

(3) U

sing standard methods, prepare and process the samples

for nutrient analysis.

This laboratory protocol will permit the determination of the

percent water in the litter; additionally the volume of the litter can

be calculated by multiplying the thickness of the layer by the area

of the collector. Aside from calculation of percent moisture in the

litter this procedure permits the estimation of density and litter

biomass per hectare. After determination of nutrient concentra-

tions the values per hectare may also be calculated.

2.4. Comparison of methods

To test collection efficiency we compared our collector

with two frequently used methods for measuring the thickness

of the litter layer. The thickness of the litter layer was

determined at 30 randomly selected points in each forest for

each method. All data were collected on 15 February 2006

and the monthly litterfall at both sites was similar during

this month (Marimon-Junior, 2007). The first method used

a rigid horizontal bar (HB) made of aluminum

(100 cm � 2 cm � 2 cm). The bar was placed on top of the

litter layer to serve as a reference and the thickness of

the litter layer was measured (Fig. 3A) at four points along the

bar by gently removing the F and H layers and then measuring

the distance from the base of the bar to the H layer with a

ruler. The second method used was a single tine (ST) of 30 cm

length (0.2 cm diameter) inserted into a wooden handle. In

this method the tine was inserted through the litter layer,

subsequently removed and the number of leaves on the tine

was counted. All the leaves on the tine were vertically

Fig. 3. Measurement of litter thickness: (A) using the horizontal bar method

(HB) and (B) using the single tine method (ST).

Table 1

Mean thickness of the litter layer (cm), standard deviation (S.D.) and coefficient

of variation (CV) for the three collection methods in both forest types,

Brosimum rubescens (MB) and mixed forest (MM) on the Vera Cruz farm,

Nova Xavantiva, Mato Grosso, Brazil

Forest type HB ST M–H

MB

Mean 1.92 ab 1.67 a 2.16 b

S.D. 0.46 0.72 0.38

CV 23.8 42.9 17.4

MM

Mean 2.06 a 2.29 a 2.28 a

S.D. 0.66 0.74 0.49

CV 31.9 50.2 16.3

Means with the same letter (within the same line) are not significantly different

at p < 0.05. HB, horizontal bar; ST = single tine; M–H = Marimon–Hay col-

lector.

Fig. 4. Mean length of time (min) necessary to collect samples with each

method in each forest as a function of mean litter thickness. HB = horizontal

bar, ST = single tine, M–H = Marimon–Hay collector. Data collected on the

Vera Cruz farm, Nova Xavantina, Mato Grosso, Brazil.

B.H. Marimon-Junior, J.D. Hay / Forest Ecology and Management 255 (2008) 2244–2250 2247

compressed to remove any space between the leaves and then the

thickness of the layer was measured with calipers (Fig. 3B).

Each method was repeated by three students (n = 10 for each

method) in each forest type to test for possible bias due to the

person making the collection. The total time spent by each

student to make the measurements with each method was also

recorded. Each student also made 10 measurements with the

M–H collector for a total of 30 randomly chosen points in each

forest types and the time required for each student to complete

these measurements was also recorded.

2.5. Data analysis

The following data were compared: (1) thickness of the litter

layer determined by each method, (2) the time necessary to

collect the data with each method and (3) differences among

students. Data were analyzed using SYSTAT 11.0 (SYSTAT

Inc., 2004) and Statistix 8.0 (Analytical Software, 2003).

Means are presented �1S.D.

3. Results

3.1. Comparison among methods

3.1.1. Thickness of the litter layer

The thickness of the litter layer measured with the three

methods was statistically different in the monodominant forest

but not in the mixed species forest (Table 1). In both forests the

standard deviation and coefficient of variation around the mean

was smaller for data collected with the M–H collector.

3.1.2. Time

The total time necessary for measurement of litter thickness

varied from 30 min (M–H) to 66 min (HB). In both forests the

sequence of mean time spent in data collection was the same,

M–H < ST < HB (Fig. 4). The mean length of time necessary

to make measurements of the litter layer in the monodominant

forest with the M–H collector was significantly lower than for

the BH method but was not different than for the ST method

(H0 = 6.48, p = 0.04). In the mixed species forest the same

result was observed (H0 = 7.2, p = 0.02).

3.2. Comparison among students

The M–H collector was the only method that did not have

significant differences in the depth of the litter layer among the

students in either area (H0 = 5.5, p = 0.06 in the monodominant

Fig. 5. Mean depth of the litter layer measured by different collectors using the

three methods (N = 10 for each method for each collector) in two forest types,

HB = horizontal bar, ST = single tine, MT = HB collector. Data collected on the

Vera Cruz farm, Nova Xavantina, Mato Grosso, Brazil. A = monodominant

forest, B = mixed species forest.

B.H. Marimon-Junior, J.D. Hay / Forest Ecology and Management 255 (2008) 2244–22502248

forest and H0 = 4.60, p = 0.10 in the mixed forest). The ST

method had significant differences among students in both

forest areas (H0 = 10.55, p = 0.005 in the monodominant forest

and H0 = 11.94, p = 0.003 in the mixed forest) but the sequence

of students differed between areas. The HB method was not

different among students in the monodominant forest

(H0 = 3.02, p = 0.22) (Fig. 5A) but was different in the mixed

forest (H0 = 20.57, p = 0.000) (Fig. 5B).

3.3. Difference between forests

The thickness of the litter layer in the monodominant forest,

measured by all three methods was smaller than in the mixed

species forest, however only for the ST method was the

difference statistically significant (H0 = 4.51, p = 0.03). The

mean number of leaves intercepted with the ST method was

higher in the monodominant forest than in the mixed species

forest (3.3 � 1.15 versus 2.9 � 0.84). However, the measured

thickness of the litter layer was not correlated with the number

of leaves in the monodominant forest (rs = 0.24, p = 0.195) but

did have a positive correlation in the mixed species forest

(rs = 0.55, p = 0.002) that characterizes a problem in extra-

polation of the results of this method.

4. Discussion

The higher degree of variability of the measurements of litter

thickness using the HB method may be explained by the

increase in the number of measurements per collection point

and by the difficulty in making the measurements since the

collector must lie on the forest floor to make the measurement.

This may also explain the significant difference in sampling

time of this method in relation to the other methods. An

independent estimate of litter thickness in both forests done in

the same month as the present study also indicated that mean

thickness was smaller in the monodominant forest (Marimon-

Junior, unpublished).

The increase in total time spent in the collection of

quantitative samples with the M–H collector in relation to

collection of data on litter thickness only was approximately

18 min for the 30 collection points. This was only 6 min slower

than the time required for data collection of litter thickness only

with the ST collector. The advantage of simultaneous collection

of quantitative samples of the litter layer is the possibility of

extrapolation in regard to nutrient and water concentration of

the litter. These parameters are important in view of the

importance of the litter layer in the maintenance of tropical

forests (see Vitousek and Sanford, 1986) and the maintenance

of the physical and chemical properties of the soil (see Hairiah

et al., 2006). If these data are adequately interpreted these

parameters are excellent aids for the determination of diverse

ecological conditions of great interest for tropical forests (for

example carbon stock) or local conditions (stock of nutrients in

different plantations).

An important advantage observed in the M–H collector

during field work was that generally the L and F layers were

removed at the transition point with the H layer (in>95% of the

samples). This is probably due to the extraction force of the

collector being greater than the retention force of the root mat at

the transition between these layers. A qualitative evaluation

indicated that the 42 tine collector should be used when the

litter layer is less than 5 cm thick since the material is more

securely held. For litter layer thicker than 5 cm the 35 tine

collector is recommended to lessen the possibility of

deformation of the litter layer and consequent under estimation

of its thickness (Marimon-Junior, unpublished).

According to Vorobeichik (1997) the thickness of the litter

layer is traditionally measured with low accuracy and is

dependent on the collector and studies in Brazil (Portela and

Santos, 2007) and in other countries are still based on

rudimentary methods (e.g. Molofsky and Augspurger, 1992;

Torti et al., 2001; Roovers, 2005; Mayor and Henkel, 2006).

The M–H collector makes an important contribution to the

resolution of this problem that normally makes field work

difficult and makes decreases the variation in the estimation of

the thickness of the litter layer. The use of a specialized

instrument for the measurement and collection of samples of

the litter layer fulfills a gap created by the non-utilization of a

B.H. Marimon-Junior, J.D. Hay / Forest Ecology and Management 255 (2008) 2244–2250 2249

specific instrument and lack of an established protocol. The

instrument and the sampling protocol presented here, if adopted

by other researchers makes possible the standardization of litter

collection in forest areas, facilitating comparison among areas

and studies.

Although our data show that our instrument is more efficient

and can reduce variability among samples there are several

limitations in regard to its use. This instrument will not be an

effective tool for collection in forests with litter thickness

greater than the length of the tines, such as might be

encountered in some temperate and boreal forests. It is possible

to increase the length of the tines, but this would probably make

the instrument too heavy for easy use. Another restriction is

related to the forest floor surface. If the surface presents

exposed rocks, has high microtopographic variability or has a

high cover of succulents, such as bromeliads, the insertion of

the tines through the litter layer might be compromised.

Differences or variability in leaf texture should not be a

problem for collection with this instrument since the tines have

a sharp point which can pierce the leaves but if the leaves have a

mean width narrower than the distance between the rows of the

tines then this might introduce a source of error into the results.

5. Conclusions

Our field tests showed that the M–H collector was more

accurate than two commonly used litter collection methods. In

two forest types the time spent in measurement of the thickness

of the litter layer was significantly shorter using the M–H

collector than for the horizontal bar but similar to the single

tine. The protocol suggested in the present study for

measurement of the litter layer and simultaneous collection

of quantitative litter samples was rapid and efficient, allowing

the collection of samples for physical and chemical analysis.

Another important advantage of the collector is the collection

of the L and F layers without the inclusion of the H layer.

Acknowledgements

The authors would like to thank the Fundacao Universidade

do Estado de Mato Grosso (UNEMAT) and the Coordenacao de

Aperfeicoamento de Pessoal do Ensino Superior do Ministerio

da Educacao (CAPES) for financial support of the Doctoral

thesis of the first author. The undergraduate students Bruno

Jordao, Louremberg Alves Peres and Rosemari Craco of the

biology course of UFMT assisted in data collection in the field.

Also to the CDT of the University of Brasilia for assistance in

obtaining the patent.

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