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CHINESE GEOGRAPHICAL SCIENCE Volume 11, Number 3, pp. 283 -288, 2001 Science Press, Beijing, China
EFFECTS OF SOIL FAUNA ON LITTER DECOMPOSITION
ZHANG Xue-ping, Zhang Si-cong, HUANG Chu-long
(Department of Geography of Harbin Normal University, Harbin 150080, P. R. China)
ABSTRACT : Forest litter is the physical makeup part of forest ecosystem. The rate of decomposition of forest litter
is low in temperate and cool temperate zones. There is important significance to search and utilize the function of soil
animals, in order to probe the material circulation and energy flow in forest ecosystem. We selected three kinds of
mesh bag with different mesh size, in which, large pore mesh bag is large enough to permit the activities of all kinds
of soil animals, medium mesh bag is designed to exclude the function of soil macrofauna, while small mesh bag is
small enough to exclude the effects of any kind of soil animals as far as possible. The decomposition time is three
years. The studying results show that: the decomposing speed of the bags with big meshes, under functions of all kinds
of soft animals, faster than the bags with medium meshes, under functions of medium and small soil animals, as well
as the bags with small meshes that excluding all possibility of functions of soil animals; in the process of decomposition
of litter, relationship of the litter lost weight with number of soil animals is not obvious clearly; the degree of functions
of soil animals to soft litter higher than hard litter; according to the analysis of diversity index, no regular changes will
happen to the diversity of soil animals as the time of decomposing samples lengthen.
KEY WORD: soil animal; forest litter; litter decomposition
CLC number: P154. 4 Document code: A Article ID: 1002-0063 (2001)03-0283-06
1 INTRODUCTION
Forest litter, which is the physical makeup part of
forest ecosystem, presents many important actions upon
ecosystem. However, if forest litter is accumulated to
excess, it will produce some nonnegligible negative in-
fluence, which could be the cause of a forest fire or the
important harbor for diseases and pests in a forest.
Therefore, there are important theoretical and practical
significances in studying the decomposition of litter in
temperate and cool temperate zone where the rate of
decomposition of forest litter is low.
The important effects of soil animals on decompo-
sition of litter have been studied abroad relatively early,
(HAGVAR et al., 1981; HOUSE et al., 1987) and a few
reports on it can also be found domest ical ly(CHEN et
al., 1984; LIAO et al., 1990; ZHANG et al., 1996;
YANG et al., 1995; GUO et al., 1992). These studies
were conducted to probe into the impacts of soil an-
imals on decomposition process of temperate coniferous
litter and the contribution of soil fauna to decomposition
course of substance, so that it can provide some theo-
retical references for the development of forest e-
cosystem
2 SAMPLE PLOT
The sample plot is located at Liangshui natural
protection area, lying in Dailing District of Yichun City
of Heilongjiang Province, and also in the southern part
Received date: 2001-04-10 Biography: ZHANG Xue-ping(1962 - ), female, a native of Harbin City, associate professor, Master. Her research interests include soil
animal ecology and environment ecology.
284 ZHANG Xue-ping,
of Xiao Hinggan Mountains, where its natural vegetation
is a mixed broad-leaved trees and korean pines forest,
and at present, after the natural vegetation of Xiao
Hinggan Mountains has almost been destroyed, it is one
of the major indigenous korean pine forest preserved
under the protection of the Chinese government, with
quite high ecological value as well as scientific research
value. The topography of plot area is low mountain, and
its zonal soil type is dark-brown forest soil. The area
presents the properties of temperate continental monsoon
climate, for its relatively high latitude. The mean an-
nual temperature is - 0. 3°C, the average annual pre-
cipitation is 676mm, the general climatic characteristics
take on long-lasting winters in which it is badly cold and
dry and short-lasting summers in which it is cool and
rainy.
The three study species of coniferous litter used by
this experiment are koyama spruce( Picea koraiensis),
fetor fir ( Able nephrolepis) and dahurian larch ( Larix
gmelini). The samples are buried in artificial spruee and
fir forst which has the similar habitat of the three
species and is dominated by koyama spruce, with fetor
fir, maple birch( Betula costata) as well as fish scale
spruce ( Picea jezoensis), while its arbor canopy density
is 0. 8, the interior of the woods is dim.
3 METHOD
In order to learn the effects of soil animals on litter
decomposition, we selected three kinds of mesh bag
with different mesh size, in which, large mesh bag is
large enough to permit the activities of all kinds of soil
animals, medium mesh bag is designed to exclude the
function of soil macrofauna, while small mesh bag is
small enough to exclude the effects of any kind of soil
animals as far as possible. Mesh bag size is 15cm ×
20cm.
The decomposition time is three years, every year
the litter bags is retrieved from study site in June, Au-
gust, October for three times. Every time each type of
leaf litter bags is respectively retrieved for 6 bags (2
large mesh bags, 2 medium mesh bags, 2 small mesh
bags), in total, there are 18 bags for the three kinds of
leaves. Then, with Tullgren funnel extractions, the soil
HUANG Chu-long
animals are collected from litter bags and the net mass
of dried litter samples are measured (144 bags of sam-
ples are firstly buried, after weighing its dry mass).
The method of sampling soil animals in the litter
layer of the plot where the samples are buried, is that it
continus for 3 years, 3 times for each year, 3 series of
samples for each time, 3 ways of sampling for each se-
ries, namely the soil macro fauna with sampling area
50cm x 50cm, are sorted out by hand, while the soil
mesofauna and soil microfauna with sampling area 10cm
× 10cm, are extracted from samples using Tullgren
funnel extractions, and the humidogene soil animals with
sampling area 5cm × 5cm, are separated from soil in
Baermann funnel , and sampled 81 altogether in three
years.
4 RESULT AND ANALYSIS
d. 1 Soil Animals in Sample Plot and Decomposition
Specimen
4. 1. 1 Soil animals of sample plot During sampling of 9 times in the 3 years for soil
animals of the litter layer in study site, we collected 41
kinds of both soil meso fauna and soil micro fauna
soil animals which summed to 12 373 ind. (Table 1),
while their dominant species were Isotomidae totaling up
to 12 515 i n d . / m 2 , Tomoceridae summing to 4 452
i n d . / m 2, Oribatida adding up 17 104 i n d . / m 2 and
Actinedida getting up to 2 315 ind /m 2. There were 20
kinds of soil macro fauna, totaling up to 1 834 ind. The
statistical result of biomass of soil macrofauna indicates
that the biomass of Enchytraeidae is dominant, occu-
pying 47.2% of the total biomass, and Lumbricidae is
in the next place, occupying 17.0%, then, being fol-
lowed by Lithobiidae 11.2% , Geophilidae 4 .6% ,
Gastropoda 3 .6%, Guliformia 3 .1%. 12 kinds of hu-
midogene soil animals were captured, and summed up
to 6 866 ind. in which, Nematode held all the trumps,
altogether 6 722 ind. , corresponding to 99 585 i nd /m 2.
4. 1.2 The quantity and kinds of soil animals in de-
composition samples The soil animals of sample bags came from its
surroundings. The summation outcome of soil animals of
Effects of Soil Fauna
sample bags with different mesh sizes for the three kinds
of leaves (spruce, fir, larch) is showed in table 1.
Table 1 demonstrates that, firstly, the quantity of soil
animals affecting the three kinds of leaves (spruce, fir,
larch) is different, appearing as larch> fir> spruce,
and the A / C ratio(namely individual numeral ratio of
Acarina to Collembola) of the three samples being
spruce > fir > larch . The outcome of analysis shows
that the texture of three types of leaves differs signifi-
cantly, larch relatively soft, fir transitional, spruce rela-
tively hard. The majority of soil animals are more easily
contributed to the decomposition of soft blades rather
than hard ones, and Collembola is especially sensitive
to the variation of texture of litter, the number of indi-
viduals of Collembola in relatively hard spruce litter is
only equivalent to one-third of that in larch litter. The
determination of the contents of protein, fat and total
sugar of three types of coniferous leaves demonstrates
that the contents of different kinds of energy substance
and total energy value of three types of litter are similar,
thus, the selective contribution of soil animals to litter
can mostly be considered as a result of influence of
texture of blades (ZHANG et al., 2001). Secondly, the
quantity of soil animals differs in sample bags with dif-
ferent mesh sizes, appearing as large mesh > medium
mesh> small mesh. The quantity of soil animals in both
fir and larch litter bags is similar in spite of different
mesh sizes, approximately in the order of 60% : 35% :
5%. The quantitative proportion of soil animals in
spruce litter bags differs in three types of mesh dis-
tinctly, appearing as 70% :25% : 5 % . Thirdly, the
species of soil animals acting in litter bags with different
mesh are not always uniform. The species and quantity
of soil animals acting in both fir and larch litter bags are
near, that of Diptera animals as well as Coleoptera in
spruce litter are distinctly less than that of litter bags of
the former two leaf species.
4. 1 .3 Comparison between soil animals in sample plot
and soil animals in litter bags
The number of soil animals in sample bags is
distinctly less than that in surroundings(Table 1),
shortly after the decomposition samples was buried in
sample plot, different kinds of soil animals came into
play and the intensity of activity(individual number,
on Litter Decomposition 285
variety number) increased with time. The characteris-
tics of distribution on quantity of soil animals in mesh
bags varied with time, differing from each other in
June, August and October annually. However, the
changing law of quantity of soil animals in all the three
meshes' sample bags of each leaf species substantially
agrees with time.
4. 2 The Diversity of Soil Animals in Decomposition
Samples
4. 2. 1 The analytic result of diversity of soil animals
The analytic result of diversity of soil animals in
three kinds (spruce, fir, larch) of decomposition sam-
ples by sampling of 9 times during the 3 years is
showed. The regularity change of diversity of soil ani-
mals of spruce, fir litter sampling in June, August and
October annually is not obvious. Among different years,
the variances in diversity index and degree of homo-
geneity of soil animals are not evident either. By di-
versity comparison among three types of meshes, we can
find that the diversity index of soil animals in samples of
large mesh and medium mesh bags is relatively higher,
and that of small mesh bags rather lower. By diversity
index Comparison of soil animals in larch samples a-
mong three times sampling in a same year, we can see
that the diversity index of it sampling in June is always
highest in the three years.
4. 2. 2 The result of comparative study of diversity
The result of comparative study of diversity indices
of soil animals in samples of three kinds(total value of
findings of a survey of nine times in three years)
demonstrate(Table 2): The variety and quantity of soil
animals in fir, larch litter bags is more than that in
spruce litter bags. However, the diversity and homo-
geneity index of soil animals are for spruce > fir >
larch. The analysis of cause: Shannon diversity index
H = -EP~lnPi , Simpson diversity index D = N( N -
1 ) / £ n i ( m - 1), in which, n, denotes of the indi-
vidual number of the species of i, iN denotes the total
individual number for all species, P~ denotes ratio of ni
to N, namely Pi = n J N. Shannon homogeneity index
is formulated as Js = H/ ln s, Simpson homogeneity in-
dex as E = d / s , i n formula, s denotes the total number
286 ZHANG Xue-ping, HUANG Chu-long
Table 1 The Number of soil animals in sampling habitat and decomposition samples
Soil animal Environment Spruce Fir Larch
litter L M S L M S L M S
Isotomidae 3379 285 117 34 703 453 97 835 806 128
Onychiuridae 484 17 14 6 38 36 1 31 25 28
Entomobryidae 211 58 31 2 57 42 2 91 29 2
Hypogastruridae 466 13 4 4 35 69 11 35 25 0
Tomoceridae 1202 250 86 9 479 280 3 509 158 3
Pseudaehorutidae 62 0 0 0 1 0 1 1 4 0
Neanuridae 47 4 0 0 12 2 0 10 9 0
Sminthuride 200 48 21 0 85 67 0 146 16 2
Oneopoduridae 42 5 1 0 9 3 0 14 5 0
Oribatida 4618 364 97 19 583 257 17 579 194 15
Gamasida 625 155 57 2 224 182 12 271 145 33
Aetinedida 299 95 36 13 144 69 50 91 96 26
Enehytraeidae 555 131 35 1 88 55 5 137 97 18
Lithobiidae 29 2 2 0 13 12 0 3 4 1
Geophilidae 33 0 0 0 2 2 0 1 7 0
Guliformia 25 5 1 0 10 2 0 8 12 0
Araneae 28 3 0 0 5 1 0 3 0 0
Formicidae 9 1 2 1 16 0 0 1 0 0
Staphylinidae 131 1 0 0 8 12 0 14 7 1
Carabidae 9 1 1 0 2 1 0 2 1 0
Elateridae 5 0 0 0 0 1 0 0 0 0
Chirpnomidae 28 0 0 0 4 1 0 6 1 1
Tabanidae 11 0 0 0 1 1 0 1 0 0
Cecidpmyiidae 62 5 3 0 5 7 0 23 5 0
Aphididae 8 0 4 0 0 3 1 1 2 1
Campodeidae 5 0 0 0 2 0 0 1 0 0
Museidae 11 4 1 0 2 0 0 0 4 0
Protura 9 1 0 0 0 0 0 0 0 0
Stratiomyiidae 14 3 2 0 6 9 0 0 0 0
Asilidae 1 0 0 0 1 0 0 0 0 0
Iehneumonidae 4 0 0 0 0 1 0 1 1 0
Nitidulidae 8 0 0 0 2 0 0 0 0 0
Thereuidae 2 0 0 0 0 0 0 0 2 0
Searabaeidae 1 0 0 0 0 0 0 0 0 0
Gastropoda 1 0 0 0 0 0 0 0 1 0
Tenebrionidae 1 0 0 0 1 0 0 0 1 0
Histeridae 3 0 0 0 1 1 0 0 0 0
Noetuidae 1 0 0 0 1 0 0 1 0 0
Symphyla 4 0 0 0 0 0 0 0 0 0
Curculionidae 2 0 0 0 0 0 0 0 0 0
Thripidae 2 0 0 0 0 0 0 0 0 0
Total number 12373 1450 515 91 2540 1569 200 2816 1657 259
L: Larger mesh M: Medium mesh S: Small mesh
of all species. By formulae, we can infer the diversity
and homogeneity largely depend on the degree of u-
niformity of individuals among species. As a result,
although the species and number of individuals of soil
animals in spruce sample bags are fewer, its diversity
index are greater than that of fir as well as larch. For
the distinctness of dominant species in composition of
soil fauna, and the apparent difference in number of
individuals among species, the general levels of the
diversity and homogeneity of soil animals are low. And
the function level of soil animals on litter can't be re-
flected perfectly.
Effects of Soil Fauna on Litter Decomposition
Table 2 The total number and diversity index of soil animals in three kinds of decomposition samples
287
Spruce Fir Larch Kinds 25 34 31 Number 2056 4309 4732 Shonnon Index 2. 1271 2. 0617 1. 999 Homogeneity 0. 6608 0. 5846 0. 5821 Shimpson 6. 5279 5. 5388 4, 9052 Homogeneity 0. 2611 0. 1629 0. 1582
4. 3 The Decomposition of Three Kinds of Specimens
4. 3. 1 The mass loss of three kinds of blades
After decomposing for three years, the mass of
three kinds of blades in sample bags with different mesh
have all reduced significantly. The experimental results
demonstrate that the rates of mass loss of different kinds
of blades during different phase are different. And ma-
terial decomposition is an uneven dynamic procedure in
a year, mass loss of leaves during eight months of Oc-
tober to June of the next year is near to that during the
two months in summer, that is to say, substantial de-
composition process principally concentrates in warm
seasons. The substantial decomposition among years can
be considered to be a relative even successive change
process. Among three years of decomposition experi-
ment, mass loss process of the first year was relatively
fast, later on, slowing gently relatively.
4. 3. 2 The impact analysis of soil animals to mass loss
during decomposition process of litter
The decomposition effect of soil animal on litter is
showed in common result of a number of processes.
Comparing mass loss processes of three kinds of blades,
each of them shows: larger mesh> medium mesh>
small mesh. Namely, soil animals accelerate the pro-
cess of decomposition. Comparing mass loss processes
of three kinds of blades, especially, that of small mesh
samples(there are still a few soil animals' functions, on
the premise of excluding soil animals' functions as far as
possible), we can know that soil animals certainly play
a part in decomposition of samples, however, such in-
fluence is with natural leaching loss of different sub-
stance of litter, microbial activity, other environment
factors functions. For the differences in material
components and law of decomposition of different types
of leaves, degree as well as level of soil animals' effect
on litter are different too, therefore, the correlation be-
tween soil animal individual number and quantity of
mass loss of litter is not obvious. The correlation anal-
ysis between soil animals' individual number and
quantity of mass loss of litter( sampling 9 times in 3
years) demonstrates it hasn't obvious correlativity a-
mong that 4 kinds of decomposition samples, and the
other two kinds present definite relativity. One of them
is medium mesh larch litter bags which soil animals'
individual number and quantity of mass loss of litter are
indicative of relatively visible relativity, r = 0 . 7 419
greater than f = 9, correlation coefficient threshold of oL
= 0. 01 is r = 0. 7 348. The other of them is medium
mesh fir litter bags which they are indicative of inverse
correlation, r = - 0 .5 661 greater than f = 9, correla-
tion coefficient threshold of r = 0 . 10 is r = 0 . 5
214. The analysis of cause: the function level of soil
animals in larch litter bags keeps supreme at all times,
and the texture of leaf blade of larch is relatively soft, so
the influence of soil animals on larch leaves is distinct.
However, the inverse correlation between quantity of
soil animals in fir sample bags and mass loss of samples
is still necessary to be studied.
4. 3. 3 The influence of soil animals' action at the num-
ber of years of decomposition of litter
Along with process of decomposition of sample bags
with three kinds of mesh sizes, mass of litter drops off,
and for the sake of difference in constructional compo-
nents of different kinds of leaf species and degree of
biological action, its rates of decomposition are also
different, even if the litter is taken from the same tree
species, the rates of decomposition are different too for
the variation of hydrothermal condition in different
months during the same year. The dynamic procedure of
weight loss in decomposition process of dead leaves can
dynamically be modeled by exponential decay model
created by Olson(ZHOU, 1991), model formula for
Xt/Xo - e TM
288 ZHANG Xue-ping,
In formula, Xo denotes initial weightiness of dead
leaves at the beginning of decomposition, X denotes
weightiness of dead leaves at the time of t, k denotes
average decomposition velocity constant (the larger k
value is, the faster rate of decomposition of dead
leaves) .
Under different degrees of action of soil animals on
three kinds of coniferous litter, after decomposition of
50% of coniferous litter has finished, the required time
to 5 can be calculated by application of the model, and
the to 95 can be calculated, too, when decomposition of
95% of litter has finished. The result is shown in Table
3.
By Ttable 3, the rates of decomposition of three
HUANG Chu-long
kinds of samples with three types of mesh relate with
degree of action of soil animals. The rate of decompo-
sition of samples in large mesh bags (under the function
of all types of soil animals) is at the soonest, decom-
position time is the shortest, and the rate of decompo-
sition of samples in medium mesh bags ( without the
function of large-scale soil animal, only the function of
micro and humidogene soil animals) is lower than that
in large mesh bags. The rate of decomposition of litter
in small mesh bags is even slower. The number of years
of decomposition is longer, for instance, the decompo-
sition of samples including spruce, fir, larch requires
more time in small mesh bag than that in large mesh
bags, and when 95% of litter has been decomposed,
Table 3 The affection of litter in decomposition time under different function intensity of soil animals
Large mesh Medium mesh Small mesh t o s t o,95 t o s t o q s t o.s t 0.95
Spruce 1.47 6.38 1.52 6.57 1.96 8.49 Fir 1.41 6. 12 1.41 6. 12 1.66 7.18 Larch 1.85 8 1.85 8 2.21 9.56
their required time rises by 2 .11 year, 1 .06 year and
1 .56 year respectively. In similar manner, when 50%
of samples has been decomposed, decomposition time is
longer in small mesh bags than that in large and medium
mesh bags.
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