Interactions between woodlice and millipedes for leaf litter … · 2016. 12. 9. · tree species...
Transcript of Interactions between woodlice and millipedes for leaf litter … · 2016. 12. 9. · tree species...
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Faculty of Sciences Department of Biology
Terrestrial Ecology Unit
Academic year 2015 – 2016
Interactions between woodlice and millipedes for
leaf litter breakdown under changing
environmental conditions.
Tom Van de Weghe
Supervisor: Prof. dr. Dries Bonte
Co-supervisor: Prof. dr. ir. Kris Verheyen
Tutor: ir. Pallieter De Smedt
Thesis submitted to obtain the degree of
Master of Science in Biology
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2016 Faculty of Sciences – Terrestrial Ecology Unit
© Deze masterproef bevat vertrouwelijke informatie en vertrouwelijke
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© All rights reserved. This thesis contains confidential information and confidential
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1. introduction 1
1.1 Macro-arthropod behavior 1
1.2 Soil biota diversity 2
1.3 Litter quality 3
1.4 General trends 4
2. Objectives 5
3. Materials and Methods 6
3.1 Study area 6
3.2 Experimental setup 6
3.2.1 Microcosms 6
3.2.2 Soil fauna 8
3.2.3 Leaf litter 9
3.2.4 Moisture and temperature manipulation 10
3.3 Statistical analysis 11
4. Results 12
4.1 Manipulation of environmental conditions 12
4.1.1 Rainfall 12
4.1.2 Soil Moisture 13
4.1.3 Temperature 14
4.2 Leaf litter decomposition 15
4.2.1 High quality litter decomposition 15
4.2.2 Low quality litter decomposition 18
4.3 Macro-detritivore weight differences 21
4.4 Macro-detritivore survival rate 22
5. Discussion 25
5.1 Environmental treatment effectiveness 25
5.2 Leaf litter decomposition by soil fauna 25
5.3 Environmental effects on soil fauna effectiveness 26
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5.4 Shift in litter preference under different environmental conditions 27
5.5 Macro-detritivore survival 28
5.6 Notes on future research 28
6. Conclusion 29
7. Summary 30
8. Samenvatting 33
9. Acknowledgements 36
10. References 37
11. Addendum 41
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1. Introduction
Europe’s history has been one of deforestation due to clearing ground for grazing and
burnings to accommodate the changing forms of agriculture. Although recent years have
seen a wave of reforestation, few forests remain without anthropogenic influences
(Bradshaw 2004). Fragmentation poses a great threat to Europe’s forests, changes in
moisture conditions can already be seen at the edge of fragmented forests. Due to higher
exposure to wind and sunlight, forest edges suffer from lower water availability compared to
the interior. These conditions could be strengthened by climate change, with IPCC reports
showing an increase in temperature up to a maximum of 4°C for the next century and
precipitation patterns changing to longer drought periods followed by heavier rains (Boer et
al. 2000; IPCC 2007). These could potentially extend these edge effects deeper into the
forest (Billings & Gaydess 2008; Riutta et al. 2012; Bogyó et al. 2015). Elevated air
temperatures result in higher saturation deficits, which increase evapotranspiration and
make regional climates increasingly dependent on rainfall (Begon et al. 2006). The effect of
drought stress can already be observed in some forest sites in Hess, Germany, where native
tree species such as Quercus robur L. show strong water-deficit damage (Gerlach et al. 2014).
As more severe summer droughts become more likely (IPCC 2007), this may have
demographic consequences for animals as well.
1.1 Macro-arthropod behavior
Macro-arthropods cope with normal seasonal droughts using both behavioral and
physiological mechanisms. Woodlice and millipedes contribute greatly to the biodiversity of
this group and are key regulators of plant litter decomposition. Basic behavior is to burrow
into the soil or to take refuge in cavities or fallen deadwood (Topp et al. 2006; David &
Handa 2010). The ability to burrow varies among species and generally millipedes burrow
deeper in the soil than woodlice (Davis et al. 1977). Physiological adaptations such as a
reduced metabolism and water vapor absorption in unsaturated air allow millipedes to
survive long periods of time in unfavorable conditions (Wright & Westh 2006) albeit paired
with lower growth rates (David 2009). This may indicate that lower levels of litter
decomposition by millipedes may be the result of reduced activity instead of higher
mortality resulting in smaller populations. Despite these adaptations, species of millipedes
with a lesser adaptation to drought (such as the order Chordeumatida) suffered significant
population declines after an exceptionally long drought (David 1990). Unlike many millipede
species that stay inactive for long periods during the dry season, woodlice emerge from their
retreats to forage at the most favorable times of the day (Shachak et al. 1979). Woodlice
generally show less adaptation to drought compared to millipedes, showing a consistent
decrease in growth and increase in mortality for a 20% decrease in relative humidity (Dixie et
al. 2015), with juveniles being particularly sensitive to unfavorable environmental conditions
(Zimmer 2005).
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In contrast to the effects of low moisture, studies suggest that higher temperatures cause
positive physiological responses in woodlice and millipedes when moisture is non-limiting
(David & Handa 2010; Dixie et al. 2015). Higher temperatures result in earlier reproduction
in spring, along with the production of larger offspring, positive effects on survival and
stress, individual growth and higher fecundity for non-diapausing species (Hassall et al.
2005). Species that diapause in winter and therefore need a period of chilling to resume
development and reproduction would still be negatively influenced by a rise in temperature.
Overwintering species may experience an acceleration of metabolic rates that would exhaust
their reserves (Hassall et al. 2005). Species that are currently living at their upper thermal
limits and are unable to shift their range are potentially threatened (Parmesan 2006).
1.2 Soil biota diversity
When elaborating on the effect of soil biota assemblages on litter decomposition rates there
are two main views. Firstly, that changes in the diversity of detritivore fauna may not have a
predictable effect on litter decomposition rates and that the functioning of the microbial-
feeding trophic group is influenced mainly by the functional attributes of the dominant
detritivore species (Cragg & Bardgett 2001; Bílá et al. 2014). And secondly, that an increase
in detritivore fauna diversity increases the nutrient mineralization and species with similar
functional traits are not functionally redundant but act synergistically on litter
decomposition (Bardgett & Chan 1999). These two seemingly contradictory views imply that
the effects of detritivore diversity on ecosystem processes are context-specific and depend
largely on species-specific characteristics of the detritivores (Zimmer et al. 2005).
Litter decomposition is significantly slower at the forest edge due to a dryer regime (Riutta
et al. 2012). The role of macro-invertebrates in this is unclear, with results from different
studies varying from a 1,6% to 66% increase in litter decomposition depending on liter type
and moisture/temperature regimes compared to situations without macro-invertebrates
present (Vasconcelos & Laurance 2005; Gonzalez & Seastedt 2001). And although soil biota
has shown a strong sensitivity to drought, some studies have shown that they remained
unaffected (Taylor et al. 2004; Staley et al. 2007). Their resistance is most likely due to
differences among species (Riutta et al. 2012). Thus, if conditions continue to become drier
or droughts become more common, functioning of the macro-invertebrates may be
reduced, and a shift in community composition towards species that are more adapted to
low moisture levels may occur (Collison et al. 2013).
However, in urban environments, such as parks or along roadways, the presence of soil
macro-invertebrates shows a clear and better exploitation of ecosystem resources (Pieper &
Weigmann 2008). Interaction between species with different functional traits become more
important in more inhospitable habitats (Zimmer et al. 2005). This suggests that the effects
of soil macro-invertebrates on leaf litter decomposition are likely to be driven by
complementarity between different species, or the facilitation of the microorganisms on
which they feed (Heemsbergen et al. 2004; Hedde et al. 2010). Although the macro-
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detritivores feed on the microorganisms that live on dead organic matter as well, they also
provide more suitable environments for these microorganisms (Anderson & Bignell 1980;
Ihnen & Zimmer 2008). Soil macro-fauna comminutes coarse litter, increasing the surface
area and therefore making the substrate more accessible for smaller organisms. As such,
their faeces serve as hotspots of digested organic material with highly available nutrients for
microbial use (Hassall et al. 1987; Rawlins et al. 2006; Ihnen & Zimmer 2008; Pieper &
Weigmann 2008; Vos et al. 2011; Gerlach et al. 2014).
1.3 Litter quality
Apart from soil moisture and rainfall, litter quality also greatly influences litter
decomposition by macro-invertebrates (Szanser et al. 2011; Slade & Riutta 2012). The
general opinion that macro-invertebrates are in rule generalists may not be true, it has been
demonstrated that many soil-invertebrates may show food specialization and preference
(Szanser et al. 2011). Litter types are generally classified as high or low quality, with high
quality litter having a lower lignin concentration and lower C/N ratio than low quality litter.
Examples of tree species with low quality litter in temperate Europe are Quercus robur L.,
Quercus ilex L., Fagus sylvatica L., Betula pubescens Ehrh., high quality litter are Fraxinus
excelsior L., Alnus glutinosa (L.) Gaertn., Alnus incana (L.) Moench (Zimmer et al. 2005; van
Geffen et al. 2011; Collison et al. 2013).
Generally, studies show that litter breakdown by macro-invertebrates is faster in high quality
litter with a lower C/N ratio and lignin concentration, with an increase of up to 30%
compared to litter breakdown without macro-invertebrates present (Zimmer et al. 2005;
Snyder et al. 2009; Meyer et al. 2011; Szanser et al. 2011; van Geffen et al. 2011; Collison et
al. 2013). Besides litter quality, litter species diversity also affects litter decomposition.
When researching if humification processes are affected by micro-invertebrate nematode
populations, nutrient release was found to be higher under mixtures than under single-
species litter treatments. With nitrogen and carbon content released from the litter
respectively 2,7 and 1,4 times higher in mixed litter (Szanser et al. 2011). This indicates that
the decomposition of diverse litter leads to a higher accumulation of humus in the substrate
compared to humification of single species litter (Szanser et al. 2011; Slade & Riutta 2012).
Monosaccharide and protein concentrations were considerably lower in macro-invertebrate
faeces compared to concentrations in leaf litter. This would indicate assimilation of these
elements in macro-invertebrate bodies. Vanillyl and syringyl units, used to describe microbial
alteration of lignin, were found in higher concentrations in macro-invertebrate faeces,
indicating a change of lignin functionalities in the invertebrate gut by microbial activity
(Rawlins et al. 2006). However, data variability explained by C/N ratio or lignin content are in
most cases smaller than the unexplained variability. This indicates other factors responsible
for litter palpability such as microbial colonization or activity on the litter (Ihnen & Zimmer
2008; Gerlach et al. 2014). Microbial colonization increased the attractiveness of a given
food source, particularly when the food source is of low quality (Ihnen & Zimmer 2008).
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1.4 General trends
Field experiments on litter decomposition by macro-arthropods have been conducted in the
past, generally using litter bags (Irmler 2000; Meyer et al. 2011; Riutta et al. 2012). But the
majority of research on this subject is done through laboratory experiments using
microcosms. These are placed in climate controlled laboratory environments with controlled
litter and macro-invertebrate compositions to test the invertebrates’ influence over a certain
time period (Bardgett & Chan 1999; Cragg & Bardgett 2001; David & Gillon 2002; Zimmer et
al. 2005; Rawlins et al. 2006; Pieper & Weigmann 2008; Snyder et al. 2009; Hedde et al.
2010; van Geffen et al. 2011; Vos et al. 2011; Collison et al. 2013; Bílá et al. 2014; Gerlach et
al. 2014; Dixie et al. 2015). Microcosms have been used in field experiments with varying
litter compositions (Szanser et al. 2011). However, very little field work has been done with
varying macro-invertebrate populations and where environmental conditions are influenced.
Although some experiments incorporate a follow-up of the rate of decomposition through
time (Cragg & Bardgett 2001; Szanser et al. 2011; Collison et al. 2013), the majority of
experiments run for single fixed time period (Irmler 2000; Hedde et al. 2010; Meyer et al.
2011; van Geffen et al. 2011; Vos et al. 2011; Riutta et al. 2012). In this experiment we
concentrated on these two points: to study the effect of set populations of macro-
invertebrates on the decomposition of presented litter in a semi-natural environment and to
follow these effects through time. Manipulation of the natural environment is done to
simulate environmental conditions predicted by climate change models, and observe how
the invertebrate populations are influenced by these conditions.
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2. Objectives
The general objective of this study is to investigate if, and to what degree, woodlouse and
millipede communities are affected by environmental conditions in a natural environment.
With this in mind we state the following hypotheses:
1. Woodlouse and millipede community compositions influence leaf litter
decomposition.
2. Environmental conditions (moisture availability and temperature) influence
woodlouse and millipede communities in their ability to decompose leaf litter.
3. Changing environmental conditions induce a change in the type of leaf litter (high
or low quality) consumption.
4. Changing environmental conditions affect survivability of woodlouse and millipede
communities.
Additionally, we will discuss if results from laboratory experiments can be extrapolated to
the field.
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3. Materials and Methods
This study was performed at the Forest & Nature Lab; part of the department of Forest and
Water Management, and member of the Natural Capital research theme of the Faculty of
Bioscience Engineering at Ghent University, Belgium.
3.1 Study area
This field study was performed in the Aelmoeseneie forest (Figure 1), located between
Ghent and the Flemish Ardennes, in the territory of Melle and Oosterzele in Belgium. The
forest is an old mixed deciduous forest consisting mostly of Quercus robur L., Quercus rubra
L., Fagus sylvatica L., Larix kaempferi Carr., Castanea sativa Mill. and Acer pseudoplatanus L.
and consists of an uninterrupted area of 39,5 ha (Labo voor Bos & Natuur 2007). Several of
the surrounding fields have been planted with Tilia L., Quercus palustris Münchh., Populus L.,
Fraxinus excelsior L., Alnus glutinosa L. and Alnus incana L.. The largest part of the forest
dates back to 1775, and is managed as a multifunctional forest by the Forest & Nature Lab of
the University of Ghent (Labo voor Bos & Natuur 2011).
Figure 1. Map of Aelmoeseneie forest (Labo voor Bos & Natuur 2011)
3.2 Experimental setup
This study was for the most part based on previous laboratory experiments using
microcosms to test the effect of macro-invertebrates on litter decomposition (Cragg &
Bardgett 2001; Zimmer et al. 2005; Pieper & Weigmann 2008). Microcosms were created,
containing leaf litter and soil fauna, and placed in the field. Environmental conditions in the
field were manipulated using overhangs and open-top chambers.
3.2.1 Microcosms
The microcosms were newly constructed using PVC tube with a height of 10 cm and
diameter of 12 cm, resulting in a surface area of 113,10 cm². Both the top and bottom were
sealed with fiberglass gauze (1 mm x 2mm mesh) to allow the passing of moisture and
micro-organisms during the experiment. We added approximately 10 mg (dry mass) of
sycamore litter (Acer pseudoplatanus) and 2 mg (dry mass) of oak litter (Quercus robur) to
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each microcosm. To restart microbial activity on the dried leaf litter, we created a microbial
wash. Soil and leaf litter was taken from the study area and soaked in water for several days.
Soil and litter was filtered out and the solution was sprayed on the microcosms one day
before the start of the experiment. To start the experiment for soil fauna effects, 4 subsets
of microcosms were set up. Monocultures of woodlice and millipedes consisted of 10
individuals of woodlice and millipedes respectively, mixed cultures consisted of 5 individuals
of each and control microcosms contained no animals (Figure 2). Before being placed in the
field, the microcosms were sprayed with the microbial wash again. Experimental density of
the animals equaled 885 individuals per m², similar to densities frequently found in the field
(Zimmer et al. 2005).
Figure 2. Preparing of microcosms (left: Tom Van de Weghe; right: Pallieter De Smedt)
To obtain data for a time series of litter decomposition on 6 separate occasions (after 1, 2, 4,
6, 8 and 12 weeks), and 3 replicates, we set up a total of 288 microcosms. The first replicate
was placed in the field in autumn, after the peak in litter fall, on October 26th, with the
second and third replicate placed respectively 1 and 3 days later. Microcosms were placed
randomly using Random.org (Haahr & Haahr 1998). After 1, 2, 4, 6, 8 and 13 weeks (due to
timing issues the last measurements were postponed until 13 weeks), three replicates for
every combination of fauna and environmental treatment were removed from the field. The
last microcosms of replicate 1 were removed January 25th. Soil fauna were removed and
weighed, and leaf litter was sorted and dried at 26°C for 3 days. After which dry mass was
measured.
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3.2.2 Soil fauna
Oniscus asellus L. (Figure 3) and
Glomeris marginata (Villers) (Figure 4)
were chosen to represent woodlice
and millipedes respectively. Both are
forest species and very prevalent in
the study area. Oniscus asellus is one
of the most widespread woodlice
species in Belgium, and can be found
in both deciduous and coniferous
forests and urban environments (Berg
et al. 2008). They aggregate under
dead wood, loose bark, rocks and leaf
litter. O. asellus is more moisture
dependant than other common
woodlice species such as its sympatric
species Porcelio scaber (Zimmer &
Topp 2000). Additionally, they are less
tolerant to rising ground water and
are therefore not present in swampy
areas. On average, they spend more
time burrowing deeper underground,
under dead wood and leaf litter and
do not climb trees as high as P. scaber
(Berg et al. 2008). Glomeris marginata
is also widely spread in Belgium and
prevalent in the study area, the highest densities can be found in natural deciduous forests
with limestone. They are rarely found under bark, usually under rocks, dead wood and litter
at the base of trees. Glomeris marginata is heat dependent and prefers well-drained soil.
They can primarily be found in relatively dry areas, where leaf litter is mixed by earthworms
(Berg et al. 2008; Voigtländer & Düker 2001).
Animals were collected by hand during mid to late October 2015 in small forest fragments
near Brakel, Belgium and around the study area (Figure 5). They were kept up to a maximum
of 1 week in plastic containers with soil and leaf litter collected on site. Pregnant females
were not used to prevent a sudden increase of juveniles during the experiment. The
difference between the average animal weight before and after the experiments served as a
measure for animal condition.
Figure 3. Oniscus asellus, 2010-09-19 Lobith - Tuindorp, havens © Martien van Berge
Figure 4. Glomeris marginata, 2014-04-26 Les Monts (Couvin) © Bert Van Der Krieken
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Figure 5. Collection areas: Bergstraat, Brakel (A) and Geraardbergsesteenweg, Gontrode (B). © 2016 Google
3.2.3 Leaf litter
Based on their chemical and physical characteristics (Table 1), leaf litter of oak (Quercus
robur) and Sycamore (Acer pseudoplatanus) were selected as respectively low quality and
high quality litter. Freshly fallen leaves were collected using nets to avoid early
decomposition of the leaves before the experiment. Collecting was done in semi-rural areas
in Hoogstraten and Bonheiden, Belgium in October 2015. In the laboratory, leaf litter was
dried at 26°C for several days to minimize microbial degradation (Zimmer & Topp 2000;
Zimmer et al. 2005). After termination of the experiments, litter remnants were dried again
at 26°C for 3 days. The difference between litter input (dry mass) to the microcosms and
litter remnants (dry mass) was used as a measure for leaf degradation. The characteristics of
the leaf litter (Table 1) were determined once prior to microcosms experiments. Lignin levels
were determined after Van Soest et al. (1991). C/N ratio was calculated after determination
of total nitrogen and organic carbon.
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Table 1. Characteristics of experimental leaf litter
Units Oak Sycamore
Potassium mg/kg 6982,68 8880,71
Sodium mg/kg 113,33 16,67
Calcium mg/kg 8977,08 12199,40
Magnesium mg/kg 221,48 566,31
Aluminium mg/kg 127,33 172,62
Iron mg/kg 185,91 288,69
Phosphate mg/kg 3209,92 1136,17
Organic carbon % 47,54 47,35
Nitrogen % 1,72 2,01
C/N
27,72 23,60
Lignin % 23,00 16,30
Oak litter showed comparable characteristics with litter used in previous experiments in
terms of C/N ratio and lignin level (Zimmer et al. 2005). Sycamore litter showed a higher C/N
ratio than most high quality litters used in previous experiments, but showed overall higher
counts of trace elements and lower levels of lignin. Furthermore, exploratory experiments
(unpublished) performed over the course of 2 and 8 weeks during August and September
2015 resulted in a faster rate of decomposition of sycamore compared to oak litter,
confirming sycamore litter as more easily decomposable and high quality litter.
3.2.4 Moisture and temperature manipulation
To manipulate moisture and temperature conditions in the field we used overhangs (Taylor
et al. 2004) and open-top chambers (Marion et al. 1997) respectively (Figure 6). Overhangs
were constructed out of 1 m² plastic sheets and were placed approximately 1 m above the
ground. Overhangs were removed biweekly to avoid simulating a complete drought. Open-
top chambers consisted of 6 Plexiglas sheets. To combine moisture and temperature
treatments overhangs were placed over open-top chambers. Rainfall was collected and
measured weekly to prevent overflow, temperature was measured on the soil surface, just
beneath the leaf litter layer. Soil moisture was measured using a soil moisture sensor. Before
placing microcosms, leaf litter was removed to allow full contact of the microcosms with the
soil.
Table 2 Overview of methods used to influence environmental conditions.
Code Overhang Open-top chamber
Natural environment N Moisture treatment M X Temperature treatment T X Combination moisture and temperature treatment C X X
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Figure 6. Field setup for moisture and temperature treatments: Natural conditions (A), Moisture treatment (B), Temperature treatment (C), Combination of moisture and temperature treatments (D).
3.3 Statistical analysis
Data was analyzed using R version 3.2.3 (R Core Team et al. 2016). General Linear Mixed
Models (GLMM) were used to test if environmental treatments were successful in
manipulating moisture and temperature levels, and to test differences in leaf litter
decomposition caused by fauna and environmental treatments. GLMM were also used to
test if fauna mortality and weight difference were affected by environmental and fauna
treatments. Factorial design was used for all treatment combinations, plot locations,
replicates and time measurements. Replicate number and plot location were considered
random factors in the GLMM. The lmer function of the lme4 package (Bates et al. 2015) was
used for all the above analyses. When the models indicated a significant difference between
means, the glht function with Tukey-adjust of the multcomp package (Hothorn et al. 2016)
was used for multiple comparison between means. Graphical representations of the data
were constructed using the ggplot2 package (Wickham 2009).
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4. Results
Results of the experiment are summarized in Table 3 (see Addendum). The results of five
microcosms were omitted for having been destroyed in the field (see Table 3, indicated in
red).
4.1 Manipulation of environmental conditions
To determine the effectiveness of the overhangs and open-top chambers in manipulating
the environmental conditions, we related the different treatments and time to the
measurements of the environmental conditions.
4.1.1 Rainfall
Analysis of the average weekly rainfall revealed a significant response to the treatments
used to influence moisture (Table 4, Figure 7). Post hoc analysis confirmed a significant
decrease in rainfall due to the overhangs used compared to the natural environment
(N-C: Estimate = 52,58 , p < 0,001 ; N-M: Estimate = 53,00 , p < 0,001). Open-top chambers
alone did not cause a significant decrease in rainfall (T-N: Estimate = 6,83 , p = 0,777). After
13 weeks, moisture and combination treatments caused a 36,05% and 37,76% reduction of
rainfall compared to natural conditions respectively. Temperature treatments only caused a
4,43% reduction.
Table 4. Results of analysis of variance for average weekly rainfall measures according to environmental treatment and time.
SS df F P
Treatment 312907,0 3 336,57 < 0,001
Time 1995280,0 5 1287,69 < 0,001
Treatment:Time 38541,0 15 8,29 < 0,001
The F values for the main effects and their interactions are presented, together with their level of significance.
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Figure 7. Effect of different environmental treatments on average weekly rainfall (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). Significance values of treatment compared to natural environment are given.
4.1.2 Soil Moisture
Moisture treatments showed a significant decrease in soil moisture (Table 5, Figure 8).
However, overhangs alone did not sufficiently reduce soil moisture levels
(N-M: Estimate = 7,30 , p = 0,102), the combination of both overhangs and open-top
chambers did significantly lower soil moisture (N-C: Estimate = 11,78, p = 0,001). Open-top
chambers alone did not cause a significant decrease in soil moisture compared to the natural
environment (T-N: Estimate = -3,54 , p = 0,682). After 13 weeks, moisture treatments caused
a 7,63% reduction in soil moisture, temperature treatments caused a 12,01% reduction and
combination treatments induced a reduction of 24,06% of soil moisture compared to natural
conditions.
Table 5. Results of analysis of variance for soil moisture measures according to environmental treatment and time.
SS df F p
Treatment 1383,5 3 12,68 0,019
Time 10186,8 5 56,01 < 0,001
Treatment:Time 1170,0 15 2,14 0,009
The F values for the main effects and their interactions are presented, together with their level of significance.
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Figure 8. Effect of different environmental treatments on soil moisture (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). Significance values of treatment compared to natural environment are given.
4.1.3 Temperature
The use of open-top chambers caused a significant rise in temperature compared to the
natural conditions (Table 6, Figure 9) (T-N: Estimate = 0,51 , p < 0,001 ; N-C: Estimate = -0,48,
p < 0,001). Overhangs alone did not cause a significant change in temperature
(N-M: Estimate = -0,005 , p = 0,999). On average, moisture treatments caused a 0,03%
increase in temperature, while temperature and combination treatments caused a 4,63%
and 4,39% increase respectively compared to natural conditions. While both time and
environmental treatments had a significant effect on temperature, no significance was found
with their interaction.
Table 6. Results of analysis of variance for temperature measures according to environmental treatment and time.
SS df F p
Treatment 17,7 3 132,28 < 0,001
Time 234,2 5 1048,13 < 0,001
The F values for the main effects are presented, together with their level of significance.
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Figure 9. Effect of different environmental treatments on temperature (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). Significance values of treatment compared to natural environment are given.
4.2 Leaf litter decomposition
We visualized the leaf litter decomposition in two ways. Firstly, though the percentage mass
loss of litter and secondly through the mass loss of litter per gram biomass of macro-
detritivores added to the microcosms, the latter was done to account for differences in
macro-detritivore weight between microcosms. Both visualizations were conducted
separately on high and low quality leaf litter.
4.2.1 High quality litter decomposition
There were significant differences in percentage mass loss of Acer pseudoplatanus between different environmental treatments (Table 7, Figure 10), moisture treatments significantly decreased mass loss compared to natural environments (N-M: Estimate = 2,17 , p = 0,003 ; N-C: Estimate = 2,42 , p < 0,001). Temperature treatment alone showed no significant difference (T-N: Estimate = -0.8015 , p = 0,565) and there was a significant difference between sole temperature treatments and combination treatments (T-C: Estimate = 1,62 , p = 0,043). As expected, time also showed a significant effect, with a higher mass loss at later time periods. Different treatments with macro-detritivore populations initially showed a significant difference in mass loss, post-hoc analysis however revealed no significant difference of macro-detritivore populations on mass loss of leaf litter compared to control microcosms (MP-CO: Estimate = 1,21 , p = 0,799 ; WL-CO: Estimate = 1,07 , p = 0,854 ; MX-CO: Estimate = 1,40 , p = 0,721). Interaction between time and macro-detritivore populations did reveal a greater effect of macro-detritivore populations at later times (2-1: Estimate = 3,94 , p = 0,037 ; 4-1: Estimate = 10,71 , p < 0,001 ; 6-1: Estimate = 15,15 , p < 0,001 ; 8-1: Estimate = 17,71 , p < 0,001 ; 13-1: Estimate = 25,52 , p < 0,001).
16
Figure 10. Effect of different environmental treatments and macro-detritivore populations on percentage of Acer leaf litter mass loss (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). Significance values of treatment compared to natural environment, and significance values of fauna treatments compared to control groups are given.
When mass loss was expressed per gram biomass of macro-detritivores added, both
woodlice and millipede populations showed a significant effect on litter decomposition. In
both cases, mixed cultures of macro-detritivores had a greater effect on litter mass loss than
monocultures (Figure 11, Figure 12). However, woodlice contributed to these effects more
than millipedes (WL-MX: Estimate = -2,78 , p = 0,021 ; MX-MP: Estimate = 1,88 , p = 0,036).
Different environmental treatments did not significantly affect woodlice populations when
mass was expressed per gram macro-detritivore biomass added, as environmental
treatments were not implemented into the model, but did affect mass loss with millipede
populations (Table 7, Figure 11, Figure 12). When mass loss was expressed per gram
millipede biomass, combination treatments of environmental conditions significantly
decreased litter mass loss compared to natural environments (N-C: Estimate = 1,77 ,
p = 0,006 ; N-M: Estimate = 0,589 , p = 0,696 ; N-T: Estimate = -0,567 , p = 0,717). In all cases
the interaction between macro-detritivore cultures and time showed a significant increase in
litter mass loss with increasing time. Woodlice populations showed a significant response
from week 4 (2-1: Estimate = 2,64 , p = 0,269 ; 4-1: Estimate = 6,33 , p < 0,001 ; 6-1: Estimate
= 8,54 , p < 0,001 ; 8-1: Estimate = 9,75 , p < 0,001 ; 13-1: Estimate = 18,36 , p < 0,001).
Millipede populations started to show a significant response from week 6
(2-1: Estimate = 1,14 , p = 0,820 ; 4-1: Estimate = 1,94 , p = 0,260 ; 6-1: Estimate = 3,47 ,
p = 0,002 ; 8-1: Estimate = 3,303 , p = 0,003 ; 13-1: Estimate = 5,44 , p < 0,001).
17
Table 7. Results of analysis of variance for high quality leaf litter mass loss according to environmental treatment, macro-detritivore populations and time.
SS df F p
Mass loss (%) Treatment 212,2 3 6,76 0,001
Population 1681,3 3 53,55 < 0,001
Time 29019,9 5 554,57 < 0,001
Population:Time 680,2 15 4,33 < 0,001
Mass loss / woodlouse biomass Population 1585,7 1 181,02 < 0,001
Time 2527,9 5 57,72 < 0,001
Population:Time 400,2 5 9,14 < 0,001
Mass loss / millipede biomass Treatment 55,6 3 3,86 0,020
Population 531,6 1 110,71 < 0,001
Time 759,2 5 31,62 < 0,001
Population:Time 55,0 5 2,29 0,049
The F values for the main effects and their interactions are presented, together with their level of significance.
Figure 11. Effect of different environmental treatments and macro-detritivore populations on Acer leaf litter mass loss per gram woodlice biomass added to microcosms (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). Significance value of mixed cultures compared to monocultures is given.
18
Figure 12. Effect of different environmental treatments and macro-detritivore populations on Acer leaf litter mass loss per gram millipede biomass added to microcosms (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). Significance values of treatment compared to natural environment, and significance values of mixed cultures compared to monocultures are given.
4.2.2 Low quality litter decomposition
Neither environmental treatments nor macro-detritivore cultures had a significant effect on
the percentage mass loss of Quercus robur litter. Different time-periods did have a
significant effect, as well as the interaction between time and different environmental
treatments (Table 8, Figure 13).
However, when mass loss was expressed per gram woodlice biomass added, macro-
detritivore populations caused a significant increase in Quercus litter mass loss. Mixed
cultures increased mass loss to a greater extent than woodlice monoculture
(WL-MX: Estimate = -0,432 , p = 0,005). Later time periods also significantly increased leaf
litter decomposition. Interaction between time and macro-detritivore populations indicated
a stronger effect of woodlice populations in later time periods (Table 8, Figure 14).
Environmental treatments did not show any significance to be admitted into the model.
When expressed per gram millipede biomass added, Quercus litter mass loss appeared to be
significantly affected by macro-detritivore cultures, different environmental treatments and
time (Table 8, Figure 15). Post hoc analysis however, showed no significant effect of
environmental treatments (N-M: Estimate = -0,095 , p = 0,965 ; T-N: Estimate = 0,077 ,
p = 0,981 ; N-C: Estimate = 0,016, p = 1,000) or between time periods. Also no significant
effect was revealed between macro-detritivore monocultures and mixed cultures
(MX-MP: Estimate = 0,118 , p = 0,558).
19
Figure 13. Effect of different environmental treatments and macro-detritivore populations on percentage of Quercus leaf litter mass loss (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment).
Table 8. Results of analysis of variance for low quality leaf litter mass loss according to environmental treatment, macro-detritivore cultures and time.
SS df F p
Mass loss (%) Treatment 45,5 3 1,66 0,223
Population 5,7 3 0,21 0,890
Time 5373,7 5 117,72 < 0,001
Treatment: Population 138,9 9 1,69 0,091
Treatment: Time 240,9 15 1,76 0,041
Population: Time 65,3 15 0,48 0,951
Treatment: Population: Time 733,2 45 1,79 0,003
Mass loss / woodlouse biomass Population 16,1 1 111,44 < 0,001
Time 18,0 5 24,88 < 0,001
Population: Time 2,5 5 3,43 0,006
Mass loss / MP biomass Treatment 0,8 3 4,40 0,005
Population 7,6 1 126,34 < 0,001
Time 4,7 5 15,48 < 0,001
Treatment: Population 0,8 3 4,27 0,006
Treatment: Time 1,5 15 1,71 0,055
Population: Time 1,0 5 3,21 0,009
Treatment: Population: Time 1,8 15 1,93 0,025
The F values for the main effects and their interactions are presented, together with their level of significance.
20
Figure 34. Effect of different environmental treatments and macro-detritivore populations on Quercus leaf litter mass loss per gram woodlice biomass added to microcosms (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). Significance values of mixed cultures compared to monocultures are given.
Figure 15. Effect of different environmental treatments and macro-detritivore populations on Quercus leaf litter mass loss per gram millipede biomass added to microcosms (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). Significance values of treatment compared to natural environment, and significance values of mixed cultures compared to monocultures are given.
21
4.3 Macro-detritivore weight differences
Different environmental treatments, macro-detritivore cultures and time periods did not
show a significant effect on woodlice weight difference. However, there was a significant
effect by both environmental treatment and macro-detritivore culture interaction, and
environmental treatment and time interactions (Table 9, Figure 16). Interaction between
temperature treatment and woodlice monocultures showed a small decrease in woodlice
weight difference (TRTMNT(T):POP(WL): Estimate = -0,000355 , p = 0,047). Also interactions
between time period 6 and temperature treatment, moisture treatment and natural
environment showed significant effect (TRTMNT(N):time.f(6): Estimate = 0,018766 , p =
0,00294 ; TRTMNT(M):time.f(6): Estimate = 0,017706 , p = 0,006 ; TRTMNT(T):time.f(6):
Estimate = 0,017216 , p = 0,00803 ).
Table 9. Results of analysis of variance for woodlice weight difference according to environmental treatment, macro-detritivore populations and time.
SS df F p
Treatment 0,000029 3 0,31 0,819
Population 0,000024 1 0,78 0,379
Time 0,000120 5 0,77 0,575
Treatment:Population 0,000268 3 2,86 0,039
Treatment:Time 0,000961 15 2,05 0,016
The F values for the main effects and their interactions are presented, together with their level of significance.
Figure 16. Effect of different environmental treatments and macro-detritivore populations on woodlice weightdifference (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). Significant values between population and environmental treatments are shown.
22
Neither environmental treatments, macro-detritivore cultures or time periods, nor any
interactions, showed a significant effect on millipede weight difference (Table 10, Figure 17).
Table 10. Results of analysis of variance for millipede weight difference according to environmental treatment, macro-detritivore populations and time.
SS df F p
Treatment 0,0004103 3 0,906 0,440
Population 0,0000005 1 0,003 0,956
Time 0,0010275 5 1,361 0,243
The F values for the main effects and their interactions are presented, together with their level of significance.
Figure 17. . Effect of different environmental treatments and macro-detritivore populations on millipede weight difference (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). No significant values of treatment compared to natural environment, nor significant values of mixed cultures compared to monocultures could be shown.
4.4 Macro-detritivore survival rate
Initially, environmental treatments and time appeared to have a significant influence on
woodlice survival rate. Additionally, interactions between treatments and time, different
population composition and time, and the three-way interaction between treatments,
populations and time significantly influenced woodlice survival (Table 11, Figure 18).
However, post hoc analysis of environmental treatments showed no significant effect of any
kind. In similar fashion, millipede survival rate initially showed to be significantly influenced
by time, interaction between time and environmental treatments, and the three-way
interaction between treatments, population compositions and time (Table 11, Figure 19).
And again, post-hoc revealed no significant effect.
23
Table 11. Results of analysis of variance for millipede and woodlice survival rate according to environmental treatment, macro-detritivore populations and time.
SS df F p
Woodlice survival rate Treatment 1019,9 3 3,103 0,029
Population 0,0 1 < 0,001 0,995
Time 1687,5 5 3,081 0,011
Treatment: Population 414,8 3 1,262 0,290
Treatment: Time 3045,4 15 1,853 0,033
Population: Time 1263,7 5 2,307 0,048
Treatment: Population: Time 4457,8 15 2,713 0,001
Millipedes survival rate Treatment 231,6 3 1,464 0,247
Population 55,4 1 1,051 0,307
Time 887,4 5 3,366 0,007
Treatment: Population 352,3 3 2,227 0,088
Treatment: Time 2648,0 15 3,348 < 0,001
Population: Time 322,1 5 1,222 0,302
Treatment: Population: Time 1973,6 15 2,495 0,003 The F values for the main effects and their interactions are presented, together with their level of significance.
Figure 18. Effect of different environmental treatments and macro-detritivore populations on woodlice survival rate (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). No significant values of treatment compared to natural environment, nor significant values of mixed cultures compared to monocultures could be shown.
24
Figure 19. Effect of different environmental treatments and macro-detritivore populations on millipede survival (C: combination treatment; M: moisture treatment; N: natural environment; T: temperature treatment). No significant values of treatment compared to natural environment, nor significant values of mixed cultures compared to monocultures could be shown.
25
5. Discussion
5.1 Environmental treatment effectiveness
To assure that we can use the different treatments to determine the effects of
environmental conditions on soil fauna and leaf litter decomposition, we must first
determine if these treatments were effective in influencing temperature and moisture
conditions during the experiment. Open-top chambers used during the experiment caused a
temperature rise of around 0,5°C. Earlier experiments conducted with open-top chambers
documented temperature increases of 1,2 – 1,8°C with a maximum of 5°C (Marion et al.
1997). Warming effects of open-top chambers are caused by solar radiation and protection
from wind. The lower than expected temperature measurements can be attributed to
shorter daytime warming during winter (Marion et al. 1997). Overhangs placed in the field
reduced weekly precipitation comparable to earlier experiments (Taylor et al. 2004).
However, soil moisture was only significantly influenced in situations with both open-top
chambers and overhangs.
The objective of using open-top chambers and overhangs was to simulate environmental
conditions based on predictions of climate change for the next century. Temperature
predictions of a 2,7°C increase (Boer et al. 2000; IPCC 2007) were not achieved by the
temperature treatments used during the experiment. Contrary to this, overhangs decreased
average precipitation to a point below predictions made by climate change models (Boer et
al. 2000; IPCC 2007), while soil moisture levels, although only achieved in combination
treatments, closely resemble predictions made about soil moisture availability (Boer et al.
2000).
Although the environmental treatments used were not able to simulate climate change
predictions for the next century, temperature and precipitation levels were influenced to a
degree to simulate short term climate change. Similar experiments conducted in laboratory
conditions did show comparable temperature and moisture conditions (Taylor et al. 2004;
van Geffen et al. 2011; Riutta et al. 2012; Collison et al. 2013; Dixie et al. 2015) to simulate
stressful conditions for soil fauna. With this, we can conclude that treatments used during
the experiment were sufficient to determine environmental effects on the ability of soil
fauna to decompose leaf litter.
5.2 Leaf litter decomposition by soil fauna
The positive effect of macro-detritivore on leaf litter decomposition is broadly accepted and
has been proven multiple times in laboratory experiments (Cragg & Bardgett 2001; Zimmer
et al. 2005; van Geffen et al. 2011; Vos et al. 2011; Collison et al. 2013; Riutta et al. 2012).
Contrary to these findings, our field study revealed no significant effect of macro-detritivore
populations on the percentage mass loss of both high quality and low quality leaf litter
26
compared to control setups, although graphical representation of data did imply a positive
effect of the fauna added.
The difference between our field study findings and the laboratory findings, as well as the
lack of statistical significance, can likely be attributed to the type of microcosms used in the
experiment. While woodlice and millipedes from the outside environment were halted by
the mesh size used, springtails and earthworms were able to enter microcosm and influence
leaf litter decomposition, as opposed to the absence of other invertebrates during
laboratory experiments.
However, when expressed per gram of macro-detritivore biomass added to the microcosms,
all macro-detritivore treatments (both mono- and mixed cultures) significantly increased
litter mass loss. Woodlice caused a greater net-effect effect per gram biomass than
millipedes, showing an even greater effect within mixed cultures. This supports the theories
that a greater macro-detritivore body mass and macro-detritivore identity are an important
factor in the increase of decomposition rates (van Geffen et al. 2011). Our findings also
partly coincide with Cragg and Bardgett (2001), who stated litter decomposition in mixed
cultures being mainly driven by the dominant animal present (our findings suggesting
woodlice being the dominant species in their ability to decompose leaf litter), but species
richness maintaining a stronger effect.
In previous laboratory studies, the effect of macro-detritivores on litter decomposition has
been shown to be more pronounced in low quality litter than in high quality litter (Cárcamo
et al. 2000). This effect has been ascribed to high quality litter being easily decomposable
and not further facilitated by the presence of macro-detritivores (Tian et al. 1995). Our
findings in the field seemingly contradict these results. All faunal treatments, both
monocultures and mixed cultures showed a stronger effect in high quality Acer litter
compared to the low quality Quercus litter. Along with a lower mass loss, no visual
fragmentation could be observed in Quercus litter, even after a period of 13 weeks in the
field. It must be noted that during our study, both high and low quality litter were presented
at the same time. And the lack of fragmentation of Quercus litter could simply be caused by
macro-detritivore preference towards high quality Acer litter. To fully determine the
difference in effect of soil fauna on high or low quality litter, future research with a similar
setup but separated litter treatments is recommended.
5.3 Environmental effects on soil fauna effectiveness
In high quality litter, moisture treatments caused a general decrease in leaf litter mass loss.
However, there was no significant interaction between soil fauna and environmental
treatments used. Contrary to previous studies (Collison et al. 2013), moisture conditions did
not show a clear modification of macro-detritivore behavior. Woodlice in particular were
surprisingly little affected by drier conditions, while these have shown to have a strong
sensitivity to unfavorable conditions (Zimmer 2005; Dixie et al. 2015).
27
These results not only extended to woodlice ability for leaf litter breakdown. When looking
at the weight differences from before and after the experiment, woodlice showed no
significant change induced by moisture treatments. Only in temperature treatments were
we able to see weightloss. And this with woodlice generally showing a positive effect to a
rise in temperature when moisture is not a limiting factor (David & Handa 2010). Millipede
communities, while being generally better adapted to harsher environments (Wright &
Westh 2006), were affected by environmental conditions in their ability for litter
decomposition. A significant decrease in leaf litter mass loss per gram millipedes added was
noted when temperature and moisture treatments were combined. However, no
environmental treatments affected millipede weightloss to a significant degree, confirming
millipede’s physiological adaptation to harsher environments (Wright & Westh 2006). The
decrease in leaf litter decomposition by millipedes combined with their condition being
unaffected by environmental conditions are also in line with the behavioral changes these
species undergo when confronted with unfavorable conditions. Millipedes are inclined to
remain inactive during these periods to preserve energy and only venture out when
conditions improve (Davis et al. 1977).
These findings on macro-detritivore effects on leaf litter decomposition were only confirmed
for low quality litter, where both woodlice and millipede communities seemed unaffected by
the environmental treatments used.
It is important to note that, while precipitation was successfully influenced by the overhangs
used, the surrounding natural environment may have acted as a buffering factor. Humidity
could not be controlled in the setups used and this may have kept moisture levels in the
microcosm at a high enough level to buffer the lack of precipitation. It should also be
mentioned that the observed moisture and temperature effects were measured during
autumn and winter, exploratory experiments (unpublished) performed in summer prior to
this study did indicate greater effects of moisture and temperature on woodlice and
millipedes. However, these exploratory experiments were performed using the same type of
microcosms. As such we essentially blocked macro-detritivore ability to burrow into the soil
or other behavioral adaptations to unfavorable conditions, influencing the fauna to an
unnatural extent. Altogether, our findings are in line with other experimental studies
running for several months and years that found soil fauna relatively unaffected by moisture
treatments (Taylor et al. 2004; Staley et al. 2007).
Given the importance of macro-detritivore communities for nutrient cycling and nutrient
uptake by plants (Bardgett & Chan 1999; Pieper & Weigmann 2008; Meyer et al. 2011), our
findings indicate that woodlice and millipedes would still be able to perform these functions
in light of short term climate change. The experiment ran during autumn and winter months
with a peak litter volume. Resistance of these species to short term environmental changes
would form a buffer to maintain a stability for nutrient cycling during these peak litter
periods in already fragmented forests for the coming decades.
28
5.4 Shift in litter preference under different environmental conditions
As stated above, macro-detritivore effect on litter decomposition has been shown to be
more pronounced in low quality litter (Tian et al. 1995; Cárcamo et al. 2000). To explain
these findings, ‘compensatory feeding’ has been put forward, i.e. soil fauna increases it’s
consumption of low quality litter to meet their nutrient requirements in unfavorable
conditions (Coûteaux et al. 1991; Hattenschwiler et al. 1999). Our findings however, showed
a stronger decomposition of high quality litter on all accounts compared to low quality litter
decomposition. Both environmental and faunal treatments have shown little effect on
Quercus-litter, along with few visual sings of animal activity. Although in contrast with the
‘complementary feeding’ theory, our findings do coincide with previous studies that did not
show these macro-detritivore effects on low quality litter either (David et al. 2001; van
Geffen et al. 2011). It should be noted that in all microcosms both litter types were still
present. Low quality litter consumption, and effects of environmental conditions thereon,
might become more prevalent as high quality food sources become more scarce.
5.5 Macro-detritivore survival
Survival of both woodlice and millipedes was high. Out of all microcosms only five resulted in
survival rates below 60%. No environmental treatment, moisture, temperature or
combination thereof, was shown to have a significant effect on mortality. Millipede
communities showed a higher, but not significantly higher, survivability. This was to be
expected as millipedes have shown to be better adapted to low moisture environments
(Wright & Westh 2006). Previous studies also reported similar findings (Pieper & Weigmann
2008; Collison et al. 2013). Significant mortalities have been reported in soil fauna, but only
when animals were exposed to a 20-30% decrease in moisture levels combined with a
temperature rise of 5°C (Dixie et al. 2015). Similar situations have been observed in natural
environments in the past during long droughts and resulted in significant population declines
of both woodlice and millipede communities (David 1990; David et al. 1991). But these levels
of humidity drops and temperature rises, however, were not achieved in our experiment.
5.6 Notes on future research
The data obtained during this study provides ample opportunities for additional research.
While we did not find any clear relationship between environmental treatments and soil
fauna on litter decomposition, previous studies done under laboratory conditions have
shown a clear effect (Cragg & Bardgett 2001; Zimmer 2005; Zimmer et al. 2005; Pieper &
Weigmann 2008; Meyer et al. 2011; van Geffen et al. 2011; Riutta et al. 2012; Collison et al.
2013; Dixie et al. 2015). Temperature treatments did not reach a level to which soil fauna
would be sufficiently stressed to induce behavioral changes. The use of smaller cone
chambers, as opposed to hexagon chambers used in this experiment, may be able to raise
temperature levels to a higher stress point, similar to levels used in previous studies.
Additionally smaller mesh size can be used to prevent earthworms influencing leaf litter
29
decomposition to some degree. Finally, a longer time period would allow high quality leaf
litter to decompose to the point where macro-detritivores would experience a greater
competition for resources, which would be likely to reveal a more pronounced interaction
between the macro-detritivore populations.
6. Conclusion
The aim of this study was to investigate the influence of environmental conditions on macro-
detritivore communities and their ability for decomposing high- and low-quality leaf litter in
a natural environment. Additionally, we compared these results with laboratory experiments
to see if these can be extrapolated to the field. The most important findings of this study are
that:
Litter decomposition was significantly decreased by lower moisture levels in high
quality litter. Low quality litter was not significantly affected by environmental
conditions.
Woodlouse and millipede populations did not show to have a significant effect on
percentage mass loss of leaf litter, but did show a significant correlation when litter
was expressed per gram macro-detritivore biomass added.
Woodlouse and millipede communities’ ability to decompose leaf litter tended to be
negatively correlated to low moisture conditions. This pattern was however not
significant.
Woodlice were more proficient than millipedes in litter decomposition, both in
monocultures and mixed cultures.
We did not find a significant effect of environmental conditions on weightloss of
macro-detritivore communities.
Environmental conditions did not significantly affect macro-detritivore mortality.
In conclusion, it can be argued that, while still effectively increasing decomposition,
woodlouse and millipede influence in breaking down leaf litter has been overestimated in
laboratory experiments, and that leaf litter mass loss is mainly driven by larger communities
of soil fauna. Additionally, environmental conditions are less likely to drive soil fauna
behavior, growth and survival, with leaf litter quality being the determining factor in these
aspects.
30
7. Summary
Few of Europe’s forests remain without anthropogenic influences. Fragmentation and
climate change pose a great danger, as drought stress could potentially extend edge effects
deeper into the forest. These effects are already observed in certain sites in Germany where
native tree species already show strong drought stress.
This drought and temperature stress is not limited to flora, macro-detritivores living off leaf
litter are also influenced by the effects of climate change. Woodlice and millipedes, key
regulators of plant litter decomposition, contribute greatly to the biodiversity of macro-
detritivores. Both groups have behavioral and physiological coping mechanisms to withstand
periods of low moisture. Basic behavior is to burrow into the soil or take refuge in small
cavities or fallen deadwood. Physiological adaptations in millipedes include a reduced
metabolism and the ability to absorb water vapor in unsaturated air. Woodlice generally
show less adaptation to drought compared to millipedes. Despite all adaptations however,
both groups suffer from a decreased in growth and increase in mortality in dryer conditions.
Higher temperatures on the other hand generally show a positive effect on woodlice and
millipedes, with a higher survival rate, growth rate and larger offspring.
Apart from moisture and temperature, litter quality also greatly influences litter
decomposition by macro-detritivores. It has been demonstrated that macro-detritivore
species show food specialization and preference. Leaf litter with lower lignin concentration
and lower C/N ratio is classified as high quality litter and is generally more easily broken
down by detritivore fauna. Contrary to this, low quality litter has a relatively high lignin
concentration and C/N ratio.
The majority of research done on litter decomposition by macro-detritivores has been
conducted through laboratory experiments using microcosms in controlled environments,
litter and macro-detritivore compositions. The objective of our study was to determine if,
and to what degree, woodlouse and millipede communities are affected by environmental
conditions in a natural environment, and to what degree results of laboratory experiments
can be extrapolated to the field.
Microcosms were created and sealed with fiberglass gauze to allow the passing of soil
moisture and micro-organisms during the experiment. Ten mg of Acer pseudoplatanus and 2
mg of Quercus robur as high and low quality liter respectively were added. To start the
experiment for soil fauna effects, 4 subsets of microcosms were set up. Monocultures of
woodlice and millipedes consisted of 10 individuals of Oniscus asellus L. and Glomeris
marginata (Villers) respectively, mixed cultures consisted of 5 individuals of each and control
microcosms contained no animals. To manipulate moisture and temperature conditions in
the field we used overhangs and open-top chambers respectively. To combine moisture and
temperature treatments overhangs were placed over open-top chambers, control setups
were placed in the field with neither. A total of 288 microcosms were placed in the field
31
divided across 3 replicates, each containing 4 subsets of environmental treatment. Each
environmental subset was again divided into 4 smaller subsets of faunal treatments. One
microcosms of each environmental/faunal treatment combination per replicate was taken
out of the field after 1, 2, 4, 6, 8 and 13 weeks to be examined.
To determine how woodlouse and millipede communities influenced leaf litter
decomposition, we calculated the mass loss of litter between the start and end of the
experiment. Mass loss was expressed both in percentage mass loss and per gram biomass of
macro-detritivores added to the microcosm at the start of the experiment. The latter was
done to account for differences in macro-detritivore weight between microcosms. Macro-
detritivore populations did not show a significant effect on liter mass loss percentage,
contrary to results from laboratory experiments. This can most likely be attributed to the
presence of foreign macro-detritivores as they were able to enter the microcosms through
the gauze used and influence mass loss. Woodlice and millipede populations did show a
significant effect when mass loss was expressed per gram of macro-detritivore biomass
added, with woodlice showing a stronger effect than millipedes, and mixed cultures affecting
litter decomposition to a greater extent overall. This supports the theory of greater macro-
detritivore biomass being an important factor in litter decomposition rates. High quality
litter was consumed to a greater extent than low quality litter, in accordance to previous
studies. However, to fully determine the difference in effect of soil fauna on high or low
quality litter, future research with a similar setup but separated litter treatments is
recommended.
To asses environmental effects on soil fauna effectiveness litter mass loss was compared
between different environmental treatments, as well as macro-detritivore weightdifference
between start and end of the experiment. Overall, low moisture conditions induced a
decrease in leaf litter mass loss. However, macro-detritivores were surprisingly little affected
by drier conditions. No interaction was found between detritivore populations and
environmental treatment, contrary to previous studies. Woodlice weightloss was unaffected
by low moisture, and only showed a slight decrease in environments with higher
temperatures. These findings contradict previous studies stating that woodlice are strongly
limited in their ability to decompose litter in unfavorable environments. Millipede weightloss
was not affected by environmental treatments at all, coinciding with previous results. It is
important to note that the surrounding environment may have acted as a buffer to maintain
moisture levels to a degree where animal populations could be sustained. And further
experimentation during warmer, dryer periods in the year are recommended.
When investigating a shift in litter preference under different environmental conditions our
findings showed a stronger decomposition of high quality litter on all accounts compared to
low quality litter decomposition. Both environmental and faunal treatments have shown
little effect on Quercus-litter, along with few visual sings of animal activity. Our findings
coincide with previous studies that did not show these macro-detritivore effects on low
32
quality litter either. It should again be noted that in all microcosms both litter types were still
present. Low quality litter consumption, and effects of environmental conditions thereon,
might become more prevalent as high quality food sources become more scarce.
Survival of both woodlice and millipedes was high. No environmental treatment, moisture,
temperature or combination thereof, was shown to have a significant effect on mortality.
Previous studies also reported similar findings. Significant mortalities have been reported in
soil fauna only when animals were exposed to a 20-30% decrease in moisture levels
combined with a temperature rise of 5°C.
We can conclude that environmental conditions show little effect on woodlouse and
millipede weight and survival and their ability to decompose leaf litter. Litter mass loss
seems to be mainly driven by litter quality, with high quality litter breaking down more easily
that low quality litter. Woodlice and millipede influence for leaf litter decomposition,
although still effectively increasing litter breakdown, seems to have been overestimated in
laboratory experiments. And although woodlice do seem to contribute to a greater extent
than millipedes, they are but a part in a larger community of detritivores that uphold leaf
litter breakdown and nutrient cycling.
33
8. Samenvatting
Slechts een klein deel van Europa’s bossen zijn vrij van menselijke invloed. Fragmentatie en
klimaatsverandering vormen een reëel gevaar, drogere condities kunnen de randeffecten
inwaarts uitbreiden. Deze effecten worden nu al geobserveerd in bepaalde sites in Duitsland
waar lokale soorten al droogtestress ondervinden.
Deze droogte- en hittestress is niet enkel van toepassing op flora, ook invertebraten
afhankelijk van bladafval worden ook beïnvloed door klimaatsverandering. Pissebedden en
miljoenpoten zijn belangrijke regulatoren voor plantafbraak en zijn verantwoordelijk voor
een groot deel van de biodiversiteit van bladafbrekende macro-invertebraten. Beide
groepen hebben verschillende aanpassingen om droogtes te weerstaan. Doorgaans wordt er
ondergronds of onder dood hout geschuild. Miljoenpoten vertonen ook een trager
metabolisme terwijl pissebedden doorgaans minder fysiologische adaptaties vertonen.
Ondanks de aanpassingen vertonen beide groepen een tragere groei en hogere mortaliteit in
drogere omstandigheden. Een hogere temperatuur toont dan weer een positief effect, met
hogere overlevingskans, groei en grotere nakomelingen.
Naast vochtigheid en temperatuur is de kwaliteit van het bladafval ook een belangrijke
factor in bladafbraak. Bladafbrekende macro-invertebraten vertonen specialisatie en
voedselvoorkeur. Bladafval met een lage lignine concentratie en C/N ratio wordt
geclassificeerd als bladafval van hoge kwaliteit en wordt gemakkelijker afgebroken door
fauna. In tegenstelling tot bladafval van lage kwaliteit, gekenmerkt door een relatief hoge
lignine concentratie en C/N ratio.
Het merendeel van onderzoek rond bladafbraak door macro-invertebraten werd gedaan via
laboratoriumexperimenten met microcosms met gecontroleerde vochtigheid, temperatuur
en populaties van fauna. De doelstellig van onze studie was om na te gaan of, en in welke
mate, pissebedden en miljoenpoten beïnvloed worden door de omgevingscondities in een
natuurlijke omgeving, en in welke mate de resultaten van labexperimenten gelden in het
veld.
Microcosms werden afgesloten met glasvezel gaas om interactie van grondvochtigheid en
micro-organismen toe te laten tijdens het experiment. 10 mg Acer pseudoplatanus en 2 mg
Quercus robur werden toegevoegd als bladafval van respectievelijk hoge en lage kwaliteit. Bij
de start van het experiment rond de invloed van fauna werden 4 subsets van microcosms
gecreëerd. Monoculturen van pissebedden en miljoenpoten bestonden uit 10 individuen van
respectievelijk Oniscus asellus L. en Glomeris marginata (Villers), gemende culturen
bestonden uit 5 individuen van elk, de controleset bevatte geen individuen. Vochtigheid en
temperatuur werden beïnvloed door middel van respectievelijk een afdak en open-top
chambers. Combinatie van vocht- en temperatuurbehandeling werd bereikt door een afdak
te plaatsen boven de open-top chambers, controles werden zonder enige behandeling in het
veld geplaatst. In totaal werden 288 microcosms verdeeld over 3 replicaten. Elk replicaat
34
bestond uit 4 subsets van de omgevingsbehandelingen, waarvan elk bestond uit 4 subsets
van fauna behandeling. Van elke combinatie van omgeving- en fauna behandeling werd na 1,
2, 4, 6, 8 en 13 weken een microcosms uit het veld gehaald voor onderzoek. En dit voor elk
replicaat.
Om na te gaan hoe pissebedden en miljoenpoten bladafbraak beïnvloeden, werd het
massaverlies van het bladafval berekend. Het verlies werd uitgedrukt in het percentage aan
verloren massa, en in gram per gram fauna biomassa toegevoegd aan de microcosms aan
het begin van het experiment. Dit laatste om het effect van de verschillende gewichten te
minimaliseren. Bladafbrekende fauna toonde geen significant effect op het percentage
massaverlies, in tegenstelling tot labexperimenten. Dit verschil kan hoogstwaarschijnlijk
worden toegeschreven aan de aanwezigheid van vreemde fauna die door de mazen van het
gebruikte gaas konden passeren en de bladafbraak beïnvloedden. Pissebed en miljoenpoot
populaties gaven wel een significant effect aan wanneer het massaverlies uitgedrukt werd in
gram per toegevoegde biomassa, waarbij pissebedden een grotere invloed dan miljoenpoten
vertoonden. Gemengde populaties vertoonden in het algemeen een sterkere invloed op
bladafbraak. Dit bevestigt de theorie dat een grotere invertebrate biomassa een belangrijke
factor is voor de snelheid van bladafbraak. Bladafval van hoge kwaliteit werd in grotere mate
geconsumeerd dan bladafval van lage kwaliteit, in overeenstemming met vorige studies. Om
dit verschil verder te onderzoeken is verder onderzoek met een gelijkaardige set-up maar
gescheiden bladafval vereist.
Om het effect van de omgevingsvariabelen op de fauna’s mogelijkheid tot bladafbraak werd
het massaverlies van bladafval onderzocht tussen de verschillende subsets van
omgevingsbehandelingen. Ook werd het gewichtsverschil van de macro-detritivoren tussen
begin en einde van het experiment bepaald. Over het algemeen veroorzaakte een lage
vochtigheid een verminderde bladafbraak. Fauna werd echter verassend weinig beïnvloed
hierdoor. Er werd geen interactie gevonden tussen de invertebrate populaties en
omgevingsvariabelen, in tegenstelling tot vorig onderzoek. Gewichtsverlies bij pissebedden
werd niet beïnvloed door lage vochtigheid en werd slechts in kleine mate verlaagd door
hogere temperaturen. Deze bevindingen spreken vorige studies tegen die verklaren dat
pissebedden een sterk verminderde bladafbraak veroorzaken in niet-ideale
omstandigheden. Gewichtsverlies bij miljoenpoten werd niet beïnvloed door de
omgevingsomstandigheden, in overeenstemming met vorige studies. Het is belangrijk te
vermelden dat de luchtvochtigheid in het studiegebied als buffer zou kunnen dienen voor de
vochtigheid binnen de microcosms. Verder onderzoek tijdens warmere, drogere periodes is
aangeraden.
We onderzochten of omgevingsvariabelen een verschil in de kwaliteit van het bladafval
induceerden. Onze bevindingen toonden een sterkere decompositie van bladafval van hoge
kwaliteit. Zowel omgevings- als fauna behandelingen toonden geen significant effect op
bladafval van lage kwaliteit, samen met een gebrek aan visuele vraat. Onze bevindingen
35
stemmen overeen met vorig onderzoek die geen effect toont van macro-detritivoren op
bladafval van lage kwaliteit. Beide types waren aanwezig in de microcosms, het gebrek aan
effect op de lage kwaliteitsbladeren kan dus ook verklaard worden door een voorkeur voor
bladafval van hoge kwaliteit door de macro-detritivoren.
Pissebedden en miljoenpoten vertoonden een hoge overleving. Geen enkele
omgevingsbehandeling vertoonden geen effect op de mortaliteit. Vorige studies vertoonden
dezelfde bevindingen. Een significante verhoging van de mortaliteit werd wel aangetoond
wanneer fauna werd blootgesteld aan een verminderde vochtigheid van 20-30%
gecombineerd met een temperatuursstijging van 5°C.
We kunnen besluiten dat omgevingsvariabelen maar weinig effect vertoont op de
mortaliteit, gewicht en de mogelijkheid tot bladafbraak van pissebedden en miljoenpoten.
Bladafbraak wordt vooral beïnvloed door de kwaliteit van het bladafval, waarbij bladafval
van hoge kwaliteit gemakkelijker afbreekt dan bladafval van lage kwaliteit. De invloed van
pissebedden en miljoenpoten op bladafbraak, hoewel deze nog steeds een invloed
uitoefenen, lijkt overschat te worden in laboratoriumexperimenten. En hoewel pissebedden
een grotere impact dan miljoenpoten vertonen, zijn zij maar een onderdeel van de grote
gemeenschap van bladafbrekende bodembiota die bladafbraak en nutriëntencyclus
onderhouden.
36
9. Acknowledgements
I sincerely want to thank my tutor ir. Pallieter De Smedt for the thought-provoking
discussion and insightful comments, for his guidance and encouragement throughout the
last year, and for his help during the many hours of collecting woodlice and millipedes, leaf
litter and setting up the microcosms used. I would like to thank my supervisor Prof. dr. Dries
Bonte and co-supervisor Prof. dr. ir. Kris Verheyen for their encouragement and helpful
comments, and for giving me the opportunity to write this thesis. I would also like to thank
Prof. dr. ir. Pieter De Frenne for allowing me the use of his temperature measurements at
the study site, ir. Willem Proesmans for his help during the fauna collection, and Luc Willems
and Greet De bruyn for the chemical analysis of leaf litter. Furthermore I would like to thank
the entire staff of the ForNaLab for creating a welcoming environment.
My wholehearted thanks goes out to Melda Altunbay for her moral and emotional support
and willingness to lend an ear during the stressful moments. I would also like to thank Daan
Mertens for his help during the fauna collection, encouragement and near endless supply of
coffee. I also wish to express my gratitude towards my parents for their patience, support
and keeping up with my mood swings this last year. Finally, I would like to thank the rest of
my family and dearest friends for their continued support.
37
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11. Addendum
Table 3. Summary of results obtained during the experiment
CODE
Weeks in the field
BEFORE AFTER Moisture
levels
Average Temperature
(°C) DATE
Weight (g) Weight (g) Surviving Weight (g) Weight (g)
WL Total
MP Total Quercus Acer WL MP WL MP Quercus Acer
Soil (%)
Total rainfall (ml)
I-CO-N-1 1 NA NA 2,05 9,98 NA NA NA NA 1,92 9,33 35,1 72 11,72 2/11/15
I-CO-N-2 2 NA NA 2,03 10,02 NA NA NA NA 1,91 8,92 22,3 73 12,18 9/11/15
I-CO-N-4 4 NA NA 1,92 9,58 NA NA NA NA 1,68 8,16 44,5 907 12,14 23/11/15
I-CO-N-6 6 NA NA 2,11 10,19 NA NA NA NA 1,81 7,61 49,2 1548 11,02 7/12/15
I-CO-N-8 8 NA NA 2,18 10,23 NA NA NA NA 1,80 7,42 48,2 1846 10,72 21/12/15
I-CO-N-12 13 NA NA 2,07 9,50 NA NA NA NA 1,55 4,97 56,2 3403 9,56 25/01/16
I-CO-M-1 1 NA NA 1,92 10,13 NA NA NA NA 1,85 9,71 19,4 0 11,72 2/11/15
I-CO-M-2 2 NA NA 1,90 9,99 NA NA NA NA 1,80 8,96 21,8 48 12,18 9/11/15
I-CO-M-4 4 NA NA 1,99 9,87 NA NA NA NA 1,75 8,22 45,6 643 12,14 23/11/15
I-CO-M-6 6 NA NA 1,92 9,97 NA NA NA NA 1,66 7,98 47,7 1047 11,02 7/12/15
I-CO-M-8 8 NA NA 1,88 9,91 NA NA NA NA 1,38 7,92 35,8 1178 10,72 21/12/15
I-CO-M-12 13 NA NA 1,91 9,89 NA NA NA NA 1,57 6,68 50,5 1760 9,56 25/01/16
I-CO-T-1 1 NA NA 2,01 10,40 NA NA NA NA 1,90 9,40 22,7 66 12,16 2/11/15
I-CO-T-2 2 NA NA 2,06 10,09 NA NA NA NA 1,91 8,73 42,2 143 12,74 9/11/15
I-CO-T-4 4 NA NA 1,92 9,98 NA NA NA NA 1,71 7,91 44,4 973 12,68 23/11/15
I-CO-T-6 6 NA NA 2,08 10,03 NA NA NA NA 1,87 7,83 41,4 1670 11,54 7/12/15
I-CO-T-8 8 NA NA 2,00 9,75 NA NA NA NA 1,67 7,96 46,3 1693 11,27 21/12/15
I-CO-T-12 13 NA NA 1,96 9,98 NA NA NA NA 1,84 6,00 44,0 3319 10,04 25/01/16
I-CO-C-1 1 NA NA 2,00 9,98 NA NA NA NA 1,98 9,00 21,7 0 12,16 2/11/15
I-CO-C-2 2 NA NA 1,92 10,21 NA NA NA NA 1,78 9,29 22,7 79 12,74 9/11/15
I-CO-C-4 4 NA NA 2,07 9,70 NA NA NA NA 1,82 8,14 26,6 888 12,68 23/11/15
I-CO-C-6 6 NA NA 1,98 10,06 NA NA NA NA 1,66 7,31 49,8 1024 11,54 7/12/15
I-CO-C-8 8 NA NA 1,99 9,94 NA NA NA NA 1,67 6,61 32,3 1117 11,27 21/12/15
I-CO-C-12 13 NA NA 2,00 10,08 NA NA NA NA 1,81 7,73 38,2 2139 10,04 25/01/16
I-WL-N-1 1 0,464 NA 1,98 10,18 10 NA 0,479 NA 1,88 8,99 42,8 72 11,72 2/11/15
I-WL-N-2 2 0,480 NA 2,04 10,04 8 NA 0,477 NA 1,90 8,74 29,3 112 12,18 9/11/15
I-WL-N-4 4 0,532 NA 1,99 9,96 10 NA 0,556 NA 1,63 7,57 50,4 1047 12,14 23/11/15
I-WL-N-6 6 0,500 NA 1,93 9,91 5 NA 0,308 NA 1,60 6,82 38,5 1529 11,02 7/12/15
I-WL-N-8 8 0,339 NA 1,96 10,22 10 NA 0,395 NA 1,59 7,25 45,5 2177 10,72 21/12/15
I-WL-N-12 13 0,418 NA 1,91 9,88 10 NA 0,449 NA 1,48 5,82 48,3 3183 9,56 25/01/16
I-WL-M-1 1 0,377 NA 2,01 9,94 10 NA 0,402 NA 1,90 9,11 19,5 0 11,72 2/11/15
I-WL-M-2 2 0,444 NA 1,98 10,06 9 NA 0,405 NA 1,81 8,64 23,4 48 12,18 9/11/15
I-WL-M-4 4 0,441 NA 1,90 10,00 10 NA 0,472 NA 1,86 7,87 46,7 653 12,14 23/11/15
I-WL-M-6 6 0,388 NA 2,02 10,02 10 NA 0,423 NA 1,77 7,66 38,7 871 11,02 7/12/15
I-WL-M-8 8 0,370 NA 1,98 10,09 9 NA 0,407 NA 1,55 6,97 38,5 1553 10,72 21/12/15
I-WL-M-12 13 0,439 NA 1,98 10,08 10 NA 0,485 NA 1,61 6,25 48,5 1760 9,56 25/01/16
I-WL-T-1 1 0,411 NA 2,09 10,16 9 NA 0,402 NA 1,98 9,08 24,9 48 12,16 2/11/15
I-WL-T-2 2 0,366 NA 1,90 9,94 10 NA 0,397 NA 1,80 8,67 26,1 81 12,74 9/11/15
42
Table 3 continued
CODE
Weeks in the field
BEFORE AFTER Moisture
levels
Average Temperature
(°C) DATE
Weight (g) Weight (g) Surviving Weight (g) Weight (g)
WL Total
MP Total Quercus Acer WL MP WL MP Quercus Acer
Soil (%)
Total rainfall (ml)
I-WL-T-4 4 0,360 NA 1,97 10,03 9 NA 0,355 NA 1,71 7,72 50,3 1047 12,68 23/11/15
I-WL-T-6 6 0,420 NA 2,07 9,85 7 NA 0,329 NA 1,78 6,92 45,7 1403 11,54 7/12/15
I-WL-T-8 8 0,392 NA 1,97 10,00 8 NA 0,360 NA 1,66 6,80 41,6 1814 11,27 21/12/15
I-WL-T-12 13 0,308 NA 1,93 10,07 10 NA 0,342 NA 1,60 6,78 42,3 2765 10,04 25/01/16
I-WL-C-1 1 0,364 NA 1,95 9,74 10 NA 0,403 NA 1,78 8,98 30,8 0 12,16 2/11/15
I-WL-C-2 2 0,343 NA 2,02 9,99 9 NA 0,331 NA 1,75 9,21 19,1 22 12,74 9/11/15
I-WL-C-4 4 0,347 NA 2,02 10,07 10 NA 0,399 NA 1,75 8,13 24,5 786 12,68 23/11/15
I-WL-C-6 6 0,375 NA 1,99 10,06 9 NA 0,376 NA 1,75 7,36 34,1 1138 11,54 7/12/15
I-WL-C-8 8 0,341 NA 2,00 10,18 10 NA 0,379 NA 1,65 7,27 38,2 1181 11,27 21/12/15
I-WL-C-12 13 0,348 NA 2,05 10,08 10 NA 0,405 NA 1,67 6,80 45,3 1937 10,04 25/01/16
I-MP-N-1 1 NA 0,973 2,04 9,99 NA 10 NA 0,769 1,94 8,94 41,7 39 11,72 2/11/15
I-MP-N-2 2 NA 0,745 2,00 10,00 NA 10 NA 0,744 1,89 8,06 40,5 85 12,18 9/11/15
I-MP-N-4 4 NA 0,692 1,96 10,07 NA 10 NA 0,740 1,69 7,42 38,3 1173 12,14 23/11/15
I-MP-N-6 6 NA 0,652 2,01 10,02 NA 10 NA 0,694 1,75 6,81 41,0 1552 11,02 7/12/15
I-MP-N-8 8 NA 0,704 1,97 10,03 NA 10 NA 0,752 1,58 5,72 52,1 2177 10,72 21/12/15
I-MP-N-12 13 NA 0,656 2,00 10,04 NA 10 NA 0,718 1,63 4,57 51,4 3248 9,56 25/01/16
I-MP-M-1 1 NA 0,604 1,96 10,07 NA 10 NA 0,626 1,77 9,44 27,1 0 11,72 2/11/15
I-MP-M-2 2 NA 0,614 1,96 9,97 NA 3 NA 0,157 1,89 8,99 30,3 21 12,18 9/11/15
I-MP-M-4 4 NA 0,659 1,91 9,92 NA 10 NA 0,677 1,65 7,51 29,9 653 12,14 23/11/15
I-MP-M-6 6 NA 0,601 2,10 9,85 NA 10 NA 0,638 1,84 6,61 41,1 1047 11,02 7/12/15
I-MP-M-8 8 NA 0,596 2,03 9,93 NA 10 NA 0,635 1,75 6,45 46,6 1193 10,72 21/12/15
I-MP-M-12 13 NA 0,717 1,93 9,93 NA 10 NA 0,734 1,67 5,06 49,1 1671 9,56 25/01/16
I-MP-T-1 1 NA 0,666 2,08 10,00 NA 10 NA 0,690 1,99 9,13 28,9 65 12,16 2/11/15
I-MP-T-2 2 NA 0,863 1,94 10,00 NA 10 NA 0,915 1,75 8,27 19,3 117 12,74 9/11/15
I-MP-T-4 4 NA 0,686 2,03 9,99 NA 10 NA 0,721 1,76 7,30 42,8 973 12,68 23/11/15
I-MP-T-6 6 NA 0,766 2,08 9,96 NA 9 NA 0,751 1,63 6,97 49,1 1576 11,54 7/12/15
I-MP-T-8 8 NA 1,098 1,95 10,04 NA 10 NA 1,178 1,65 5,76 32,8 1814 11,27 21/12/15
I-MP-T-12 13 NA 0,949 1,97 10,08 NA 10 NA 1,015 1,69 4,46 43,5 3458 10,04 25/01/16
I-MP-C-1 1 NA 0,693 1,92 9,93 NA 10 NA 0,669 1,83 9,06 19,1 0 12,16 2/11/15
I-MP-C-2 2 NA 0,560 1,95 10,02 NA 10 NA 0,550 1,69 8,38 31,5 83 12,74 9/11/15
I-MP-C-4 4 NA 0,580 2,02 9,96 NA 10 NA 0,572 1,85 8,00 46,9 801 12,68 23/11/15
I-MP-C-6 6 NA 0,640 1,96 9,98 NA 10 NA 0,632 1,69 7,44 29,7 1024 11,54 7/12/15
I-MP-C-8 8 NA 0,543 2,00 9,98 NA 10 NA 0,541 1,57 6,59 23,3 1117 11,27 21/12/15
I-MP-C-12 13 NA 0,574 1,94 10,04 NA 9 NA 0,480 1,63 6,05 34,4 1824 10,04 25/01/16
I-MX-N-1 1 0,136 0,251 1,92 9,89 5 5 0,155 0,275 1,75 8,81 28,7 72 11,72 2/11/15
I-MX-N-2 2 0,214 0,259 2,00 10,00 3 5 0,136 0,277 1,88 8,43 33,5 73 12,18 9/11/15
I-MX-N-4 4 0,171 0,536 2,08 9,83 5 5 0,213 0,562 1,84 7,20 58,0 1173 12,14 23/11/15
I-MX-N-6 6 0,267 0,351 2,09 9,91 5 5 0,292 0,337 1,75 7,33 30,9 1735 11,02 7/12/15
I-MX-N-8 8 0,274 0,283 1,91 9,93 5 5 0,279 0,282 1,56 6,77 51,1 1846 10,72 21/12/15
43
Table 3 continued
CODE
Weeks in the field
BEFORE AFTER Moisture
levels
Average Temperature
(°C) DATE
Weight (g) Weight (g) Surviving Weight (g) Weight (g)
WL Total
MP Total Quercus Acer WL MP WL MP Quercus Acer
Soil (%)
Total rainfall (ml)
I-MX-N-12 13 0,222 0,283 2,01 9,81 5 5 0,243 0,291 1,67 6,84 53,5 3693 9,56 25/01/16
I-MX-M-1 1 0,150 0,282 1,95 9,83 5 5 0,151 0,265 1,84 9,19 26,9 0 11,72 2/11/15
I-MX-M-2 2 0,245 0,280 1,94 10,10 5 5 0,251 0,273 1,78 9,04 43,3 85 12,18 9/11/15
I-MX-M-4 4 0,216 0,354 2,00 10,01 5 5 0,234 0,351 1,68 7,82 25,9 903 12,14 23/11/15
I-MX-M-6 6 0,146 0,319 1,92 9,91 4 5 0,139 0,327 1,63 7,66 40,2 1047 11,02 7/12/15
I-MX-M-8 8 0,111 0,277 1,91 9,98 5 5 0,142 0,290 1,61 7,42 51,0 1110 10,72 21/12/15
I-MX-M-12 13 0,152 0,245 2,07 10,12 5 5 0,192 0,236 1,73 6,23 45,2 1671 9,56 25/01/16
I-MX-T-1 1 0,153 0,223 2,00 9,84 4 5 0,148 0,237 1,80 8,93 45,9 60 12,16 2/11/15
I-MX-T-2 2 0,134 0,228 2,09 10,05 5 5 0,158 0,240 1,96 8,85 20,2 117 12,74 9/11/15
I-MX-T-4 4 0,168 0,185 1,92 9,75 5 5 0,218 0,216 1,68 7,88 53,9 1047 12,68 23/11/15
I-MX-T-6 6 0,171 0,224 2,06 9,79 5 1 0,206 0,097 1,77 7,51 34,1 1351 11,54 7/12/15
I-MX-T-8 8 0,178 0,181 1,95 9,86 4 5 0,175 0,199 1,65 7,45 42,3 1721 11,27 21/12/15
I-MX-T-12 13 0,104 0,280 1,93 9,96 5 5 0,137 0,289 1,70 5,93 48,9 3319 10,04 25/01/16
I-MX-C-1 1 0,200 0,305 1,99 9,94 5 5 0,242 0,326 1,91 9,21 23,8 0 12,16 2/11/15
I-MX-C-2 2 0,141 0,332 2,02 9,87 5 5 0,175 0,355 1,90 8,71 19,7 10 12,74 9/11/15
I-MX-C-4 4 0,243 0,345 1,98 10,02 5 5 0,248 0,358 1,75 7,80 39,1 888 12,68 23/11/15
I-MX-C-6 6 0,235 0,454 2,09 10,04 4 5 0,181 0,474 1,88 7,03 35,5 1024 11,54 7/12/15
I-MX-C-8 8 0,349 0,444 1,94 9,96 4 5 0,314 0,461 1,79 7,19 36,3 1052 11,27 21/12/15
I-MX-C-12 13 0,216 0,407 2,08 10,12 4 5 0,180 0,424 1,84 5,55 43,1 2126 10,04 25/01/16
II-CO-N-1 1 NA NA 1,91 9,94 NA NA NA NA 1,81 9,10 36,6 36 11,54 3/11/15
II-CO-N-2 2 NA NA 1,95 10,05 NA NA NA NA 1,86 8,69 43,2 112 12,37 10/11/15
II-CO-N-4 4 NA NA 1,97 10,15 NA NA NA NA 1,55 8,09 48,5 1059 11,98 24/11/15
II-CO-N-6 6 NA NA 1,90 9,97 NA NA NA NA 1,63 7,49 43,5 1735 10,99 8/12/15
II-CO-N-8 8 NA NA 1,89 9,73 NA NA NA NA 1,63 7,57 53,6 1905 10,71 22/12/15
II-CO-N-12 13 NA NA 2,00 9,74 NA NA NA NA 1,61 6,11 45,9 3248 9,52 26/01/16
II-CO-M-1 1 NA NA 1,85 9,85 NA NA NA NA 1,75 9,21 38,1 0 11,54 3/11/15
II-CO-M-2 2 NA NA 1,99 10,08 NA NA NA NA 1,84 8,94 18,5 17 12,37 10/11/15
II-CO-M-4 4 NA NA 1,90 9,67 NA NA NA NA 1,73 7,92 31,6 839 11,98 24/11/15
II-CO-M-6 6 NA NA 1,72 9,79 NA NA NA NA 1,40 7,69 23,3 1197 10,99 8/12/15
II-CO-M-8 8 NA NA 1,95 9,75 NA NA NA NA 1,65 6,91 42,7 1193 10,71 22/12/15
II-CO-M-12 13 NA NA 1,90 9,96 NA NA NA NA 1,56 7,24 43,8 2000 9,52 26/01/16
II-CO-T-1 1 NA NA 2,09 9,60 NA NA NA NA 1,87 8,73 28,9 65 11,95 3/11/15
II-CO-T-2 2 NA NA 1,88 9,83 NA NA NA NA 1,69 8,30 25,7 132 12,94 10/11/15
II-CO-T-4 4 NA NA 1,80 9,83 NA NA NA NA 1,66 7,90 44,1 1099 12,49 24/11/15
II-CO-T-6 6 NA NA 2,00 9,62 NA NA NA NA 1,73 7,46 31,7 1498 11,52 8/12/15
II-CO-T-8 8 NA NA 1,95 9,75 NA NA NA NA 1,35 7,16 49,3 1985 11,26 22/12/15
II-CO-T-12 13 NA NA 1,79 9,81 NA NA NA NA 1,44 6,42 31,6 3075 10,01 26/01/16
II-CO-C-1 1 NA NA 1,91 9,77 NA NA NA NA 1,75 9,00 22,2 0 11,95 3/11/15
II-CO-C-2 2 NA NA 2,00 9,62 NA NA NA NA 1,83 8,64 18,5 10 12,94 10/11/15
44
Table 3 continued
CODE
Weeks in the field
BEFORE AFTER Moisture
levels
Average Temperature
(°C) DATE
Weight (g) Weight (g) Surviving Weight (g) Weight (g)
WL Total
MP Total Quercus Acer WL MP WL MP Quercus Acer
Soil (%)
Total rainfall (ml)
II-CO-C-4 4 NA NA 1,86 10,12 NA NA NA NA 1,64 8,48 26,6 728 12,49 24/11/15
II-CO-C-6 6 NA NA 1,82 10,02 NA NA NA NA 1,53 7,77 34,7 1041 11,52 8/12/15
II-CO-C-8 8 NA NA 1,99 10,30 NA NA NA NA 1,83 8,38 43,5 1091 11,26 22/12/15
II-CO-C-12 13 NA NA 1,82 10,06 NA NA NA NA 1,45 6,99 44,3 2139 10,01 26/01/16
II-WL-N-1 1 0,657 NA 1,96 9,70 9 NA 0,485 NA 1,82 8,63 47,1 36 11,54 3/11/15
II-WL-N-2 2 0,508 NA 1,78 9,91 10 NA 0,552 NA 1,67 8,40 22,7 110 12,37 10/11/15
II-WL-N-4 4 0,294 NA 2,07 10,08 9 NA 0,323 NA 1,80 8,05 41,7 1177 11,98 24/11/15
II-WL-N-6 6 0,393 NA 1,87 9,67 9 NA 0,423 NA 1,59 6,61 33,9 1352 10,99 8/12/15
II-WL-N-8 8 0,430 NA 2,08 10,37 8 NA 0,373 NA 1,80 7,55 41,9 1662 10,71 22/12/15
II-WL-N-12 13 0,430 NA 2,00 10,06 10 NA 0,490 NA 1,60 6,62 51,2 3248 9,52 26/01/16
II-WL-M-1 1 0,444 NA 1,84 9,90 10 NA 0,495 NA 1,75 9,23 24,9 0 11,54 3/11/15
II-WL-M-2 2 0,666 NA 1,98 9,65 5 NA 0,287 NA 1,80 8,21 24,1 17 12,37 10/11/15
II-WL-M-4 4 0,595 NA 1,98 9,58 10 NA 0,419 NA 1,78 7,57 34,7 808 11,98 24/11/15
II-WL-M-6 6 0,315 NA 1,89 10,19 10 NA 0,381 NA 1,57 7,65 45,8 1197 10,99 8/12/15
II-WL-M-8 8 0,570 NA 1,94 9,71 10 NA 0,661 NA 1,56 6,37 47,4 1553 10,71 22/12/15
II-WL-M-12 13 0,332 NA 2,07 9,80 9 NA 0,377 NA 1,73 6,45 43,3 1760 9,52 26/01/16
II-WL-T-1 1 0,703 NA 2,05 9,83 10 NA 0,574 NA 1,97 9,02 35,8 66 11,95 3/11/15
II-WL-T-2 2 0,661 NA 2,09 10,10 10 NA 0,519 NA 1,95 8,70 17,0 116 12,94 10/11/15
II-WL-T-4 4 0,342 NA 1,94 9,68 10 NA 0,381 NA 1,85 7,67 41,6 906 12,49 24/11/15
II-WL-T-6 6 0,340 NA 1,92 9,95 8 NA 0,342 NA 1,66 7,04 40,6 1403 11,52 8/12/15
II-WL-T-8 8 0,498 NA 1,80 9,75 10 NA 0,575 NA 1,60 6,74 45,4 1756 11,26 22/12/15
II-WL-T-12 13 0,352 NA 1,88 9,81 10 NA 0,340 NA 1,46 5,37 42,4 3458 10,01 26/01/16
II-WL-C-1 1 0,361 NA 1,93 9,82 10 NA 0,422 NA 1,80 9,07 27,1 0 11,95 3/11/15
II-WL-C-2 2 0,477 NA 2,09 9,67 10 NA 0,511 NA 1,90 8,18 17,3 58 12,94 10/11/15
II-WL-C-4 4 0,425 NA 1,94 10,16 9 NA 0,406 NA 1,61 8,18 44,9 728 12,49 24/11/15
II-WL-C-6 6 0,525 NA 1,94 9,79 8 NA 0,330 NA 1,64 7,05 17,3 1074 11,52 8/12/15
II-WL-C-8 8 0,378 NA 1,81 9,91 10 NA 0,407 NA 1,55 7,46 19,0 1004 11,26 22/12/15
II-WL-C-12 13 0,503 NA 1,95 9,99 9 NA 0,500 NA 1,71 4,91 49,3 2188 10,01 26/01/16
II-MP-N-1 1 NA 0,713 2,09 9,90 NA 9 NA 0,636 1,90 8,86 38,7 44 11,54 3/11/15
II-MP-N-2 2 NA 0,706 1,86 9,86 NA 10 NA 0,760 1,66 8,02 30,4 73 12,37 10/11/15
II-MP-N-4 4 NA 0,645 1,87 10,03 NA 8 NA 0,676 1,68 7,60 52,8 1061 11,98 24/11/15
II-MP-N-6 6 NA 0,550 1,86 9,83 NA 10 NA 0,617 1,62 6,82 37,7 1735 10,99 8/12/15
II-MP-N-8 8 NA 1,263 1,78 9,92 NA 10 NA 1,095 1,51 5,80 53,0 2226 10,71 22/12/15
II-MP-N-12 13 NA 0,536 1,91 9,74 NA 10 NA 0,587 1,51 5,45 55,3 3065 9,52 26/01/16
II-MP-M-1 1 NA 0,574 2,08 9,74 NA 10 NA 0,560 1,94 9,02 25,0 0 11,54 3/11/15
II-MP-M-2 2 NA 0,568 1,97 9,93 NA 9 NA 0,514 1,87 8,44 19,9 42 12,37 10/11/15
II-MP-M-4 4 NA 0,916 2,01 9,85 NA 10 NA 0,955 1,81 7,75 45,3 808 11,98 24/11/15
II-MP-M-6 6 NA 0,625 1,96 9,83 NA 10 NA 0,695 1,73 6,59 35,9 1197 10,99 8/12/15
II-MP-M-8 8 NA 0,874 1,84 10,04 NA 10 NA 0,909 1,65 6,55 47,6 1193 10,71 22/12/15
45
Table 3 continued
CODE
Weeks in the field
BEFORE AFTER Moisture
levels
Average Temperature
(°C) DATE
Weight (g) Weight (g) Surviving Weight (g) Weight (g)
WL Total
MP Total Quercus Acer WL MP WL MP Quercus Acer
Soil (%)
Total rainfall (ml)
II-MP-M-12 13 NA 0,340 1,98 10,15 NA 10 NA 0,374 1,84 6,19 43,2 2591 9,52 26/01/16
II-MP-T-1 1 NA 0,433 1,87 9,90 NA 10 NA 0,438 1,67 9,09 33,7 48 11,95 3/11/15
II-MP-T-2 2 NA 0,705 1,91 9,88 NA 10 NA 0,606 1,75 8,18 45,0 143 12,94 10/11/15
II-MP-T-4 4 NA 0,564 1,89 9,96 NA 10 NA 0,597 1,75 7,58 48,9 1113 12,49 24/11/15
II-MP-T-6 6 NA 0,880 1,96 10,08 NA 8 NA 0,772 1,66 6,62 33,5 1351 11,52 8/12/15
II-MP-T-8 8 NA 0,541 2,01 9,89 NA 8 NA 0,576 1,79 6,59 33,5 1736 11,26 22/12/15
II-MP-T-12 13 NA 0,646 2,02 10,11 NA 10 NA 0,695 1,44 4,49 46,1 3458 10,01 26/01/16
II-MP-C-1 1 NA 0,904 1,91 10,00 NA 10 NA 0,750 1,78 9,00 19,0 0 11,95 3/11/15
II-MP-C-2 2 NA 0,681 1,94 10,02 NA 10 NA 0,710 1,75 8,60 36,0 83 12,94 10/11/15
II-MP-C-4 4 NA 0,755 2,13 9,85 NA 9 NA 0,520 1,86 7,76 34,8 728 12,49 24/11/15
II-MP-C-6 6 NA 0,770 1,88 9,79 NA 9 NA 0,608 1,59 7,09 26,1 1024 11,52 8/12/15
II-MP-C-8 8 NA 1,285 2,00 10,04 NA 10 NA 1,379 1,47 5,92 39,2 1091 11,26 22/12/15
II-MP-C-12 13 NA 1,182 1,85 9,75 NA 6 NA 1,016 1,39 4,67 37,0 1937 10,01 26/01/16
II-MX-N-1 1 0,185 0,184 1,94 9,84 5 5 0,220 0,206 1,83 8,94 33,6 44 11,54 3/11/15
II-MX-N-2 2 0,221 0,500 1,90 10,01 5 5 0,265 0,359 1,80 8,44 43,1 73 12,37 10/11/15
II-MX-N-4 4 0,323 0,229 1,95 9,71 5 5 0,194 0,271 1,73 7,06 51,4 1093 11,98 24/11/15
II-MX-N-6 6 0,207 0,193 1,99 9,96 4 5 0,170 0,232 1,49 7,02 41,9 1529 10,99 8/12/15
II-MX-N-8 8 0,292 0,578 2,05 10,03 2 2 0,129 0,190 1,59 6,73 47,3 1959 10,71 22/12/15
II-MX-N-12 13 0,146 0,865 2,05 10,00 5 5 0,180 0,709 1,63 5,61 47,8 3302 9,52 26/01/16
II-MX-M-1 1 0,221 0,675 2,05 9,81 4 5 0,198 0,683 1,87 8,98 27,4 0 11,54 3/11/15
II-MX-M-2 2 0,180 0,532 1,96 10,14 5 5 0,191 0,560 1,82 8,54 27,0 48 12,37 10/11/15
II-MX-M-4 4 0,280 0,530 2,05 9,98 5 5 0,300 0,575 1,84 7,78 37,1 1027 11,98 24/11/15
II-MX-M-6 6 0,381 0,351 2,11 9,83 5 5 0,420 0,391 2,02 6,67 40,9 1152 10,99 8/12/15
II-MX-M-8 8 0,392 0,468 1,90 10,19 5 5 0,236 0,497 1,62 6,68 35,7 1280 10,71 22/12/15
II-MX-M-12 13 0,251 0,576 1,88 9,83 5 4 0,276 0,400 1,53 5,02 43,9 2591 9,52 26/01/16
II-MX-T-1 1 0,264 0,446 1,90 9,83 5 5 0,300 0,476 1,73 8,80 33,5 52 11,95 3/11/15
II-MX-T-2 2 0,260 0,455 1,99 10,00 5 5 0,294 0,285 1,82 8,38 29,2 100 12,94 10/11/15
II-MX-T-4 4 0,228 0,597 2,05 9,96 1 4 0,063 0,402 1,75 7,31 39,7 901 12,49 24/11/15
II-MX-T-6 6 0,279 0,180 1,96 9,89 5 5 0,306 0,188 1,59 6,92 39,4 1438 11,52 8/12/15
II-MX-T-8 8 0,343 0,538 1,93 9,98 5 5 0,379 0,350 1,55 6,91 54,4 1985 11,26 22/12/15
II-MX-T-12 13 0,155 0,328 1,94 9,78 5 5 0,184 0,348 1,40 6,29 44,8 2765 10,01 26/01/16
II-MX-C-1 1 0,290 0,431 1,98 9,86 5 5 0,312 0,246 1,86 9,00 20,7 0 11,95 3/11/15
II-MX-C-2 2 0,243 0,316 2,11 9,84 3 5 0,178 0,308 1,96 8,60 24,1 79 12,94 10/11/15
II-MX-C-4 4 0,180 0,320 1,95 10,12 4 5 0,128 0,329 1,71 7,78 26,8 705 12,49 24/11/15
II-MX-C-6 6 0,434 0,441 1,92 9,81 5 4 0,297 0,204 1,74 7,67 19,6 1138 11,52 8/12/15
II-MX-C-8 8 0,210 0,225 1,95 9,96 5 5 0,242 0,252 1,62 6,91 46,2 1169 11,26 22/12/15
II-MX-C-12 13 0,230 0,411 2,05 10,19 4 5 0,210 0,230 1,53 6,72 40,8 1937 10,01 26/01/16
III-CO-N-1 1 NA NA 1,93 10,12 NA NA NA NA 1,80 9,31 24,6 66 11,24 5/11/15
III-CO-N-2 2 NA NA 2,02 10,00 NA NA NA NA 1,82 8,75 27,3 112 12,52 12/11/15
46
Table 3 continued
CODE
Weeks in the field
BEFORE AFTER Moisture
levels
Average Temperature
(°C) DATE
Weight (g) Weight (g) Surviving Weight (g) Weight (g)
WL Total
MP Total Quercus Acer WL MP WL MP Quercus Acer
Soil (%)
Total rainfall (ml)
III-CO-N-4 4 NA NA 2,09 9,98 NA NA NA NA 1,81 8,05 53,0 1224 11,63 26/11/15
III-CO-N-6 6 NA NA 1,96 10,04 NA NA NA NA 1,62 7,41 59,1 1580 10,87 10/12/15
III-CO-N-8 8 NA NA 1,94 10,10 NA NA NA NA 1,67 6,88 46,2 1966 10,68 24/12/15
III-CO-N-12 13 NA NA 1,95 10,01 NA NA NA NA 1,51 6,76 46,6 2733 9,44 28/01/16
III-CO-M-1 1 NA NA 1,99 10,00 NA NA NA NA 1,86 9,17 50,3 3 11,24 5/11/15
III-CO-M-2 2 NA NA 1,98 10,09 NA NA NA NA 1,75 8,91 30,3 63 12,52 12/11/15
III-CO-M-4 4 NA NA 2,04 10,02 NA NA NA NA 1,83 8,11 32,1 1027 11,63 26/11/15
III-CO-M-6 6 NA NA 2,02 10,02 NA NA NA NA 1,77 7,72 39,0 871 10,87 10/12/15
III-CO-M-8 8 NA NA 1,94 10,04 NA NA NA NA 1,62 7,50 39,7 1193 10,68 24/12/15
III-CO-M-12 13 NA NA 2,00 10,00 NA NA NA NA 1,65 6,71 46,9 2351 9,44 28/01/16
III-CO-T-1 1 NA NA 1,97 9,98 NA NA NA NA 1,88 9,07 39,4 79 11,67 5/11/15
III-CO-T-2 2 NA NA 2,02 10,00 NA NA NA NA 1,86 8,84 25,0 117 13,09 12/11/15
III-CO-T-4 4 NA NA 2,02 9,99 NA NA NA NA 1,81 7,80 44,9 1046 12,13 26/11/15
III-CO-T-6 6 NA NA 2,08 10,02 NA NA NA NA 1,53 7,74 39,1 1383 11,39 10/12/15
III-CO-T-8 8 NA NA 1,94 10,03 NA NA NA NA 1,61 7,19 30,9 1718 11,23 24/12/15
III-CO-T-12 13 NA NA 1,97 10,00 NA NA NA NA 1,36 6,63 57,1 2802 9,94 28/01/16
III-CO-C-1 1 NA NA 1,98 10,03 NA NA NA NA 1,87 9,31 25,0 6 11,67 5/11/15
III-CO-C-2 2 NA NA 1,96 9,99 NA NA NA NA 1,82 8,68 39,6 83 13,09 12/11/15
III-CO-C-4 4 NA NA 1,95 10,07 NA NA NA NA 1,73 8,11 28,8 819 12,13 26/11/15
III-CO-C-6 6 NA NA 2,00 9,95 NA NA NA NA 1,73 7,98 21,9 939 11,39 10/12/15
III-CO-C-8 8 NA NA 1,97 9,98 NA NA NA NA 1,65 7,46 31,5 1117 11,23 24/12/15
III-CO-C-12 13 NA NA 1,95 9,98 NA NA NA NA 1,59 7,11 32,3 1863 9,94 28/01/16
III-WL-N-1 1 0,281 NA 1,97 9,99 8 NA 0,250 NA 1,86 9,06 30,9 77 11,24 5/11/15
III-WL-N-2 2 0,352 NA 1,98 9,96 10 NA 0,366 NA 1,86 8,75 38,1 73 12,52 12/11/15
III-WL-N-4 4 0,335 NA 1,99 9,98 6 NA 0,205 NA 1,78 7,66 59,1 1054 11,63 26/11/15
III-WL-N-6 6 0,331 NA 2,08 10,06 5 NA 0,188 NA 1,71 7,14 46,9 1374 10,87 10/12/15
III-WL-N-8 8 0,272 NA 1,97 10,04 9 NA 0,265 NA 1,83 6,80 48,6 1894 10,68 24/12/15
III-WL-N-12 13 0,405 NA 2,00 9,95 8 NA 0,371 NA 1,59 5,91 54,1 3059 9,44 28/01/16
III-WL-M-1 1 0,393 NA 2,04 10,07 10 NA 0,399 NA 1,86 9,23 20,5 5 11,24 5/11/15
III-WL-M-2 2 0,314 NA 2,07 9,95 10 NA 0,320 NA 1,91 8,78 21,4 19 12,52 12/11/15
III-WL-M-4 4 0,420 NA 2,00 9,94 10 NA 0,420 NA 1,80 8,17 44,5 808 11,63 26/11/15
III-WL-M-6 6 0,610 NA 1,96 9,96 8 NA 0,511 NA 1,66 7,58 45,5 1098 10,87 10/12/15
III-WL-M-8 8 0,297 NA 1,93 10,06 7 NA 0,226 NA 1,60 7,46 46,4 1229 10,68 24/12/15
III-WL-M-12 13 0,473 NA 1,97 10,01 10 NA 0,514 NA 1,57 6,13 51,6 1800 9,44 28/01/16
III-WL-T-1 1 0,477 NA 1,98 10,07 9 NA 0,464 NA 1,84 9,15 36,4 53 11,67 5/11/15
III-WL-T-2 2 0,315 NA 1,95 10,00 7 NA 0,211 NA 1,78 8,72 35,2 85 13,09 12/11/15
III-WL-T-4 4 0,368 NA 1,96 10,05 7 NA 0,293 NA 1,76 8,06 45,3 1089 12,13 26/11/15
III-WL-T-6 6 0,476 NA 1,98 10,04 7 NA 0,306 NA 1,53 7,42 26,5 1526 11,39 10/12/15
III-WL-T-8 8 0,355 NA 1,96 10,03 9 NA 0,305 NA 1,58 7,37 53,1 2103 11,23 24/12/15
47
Table 3 continued
CODE
Weeks in the field
BEFORE AFTER Moisture
levels
Average Temperature
(°C) DATE
Weight (g) Weight (g) Surviving Weight (g) Weight (g)
WL Total
MP Total Quercus Acer WL MP WL MP Quercus Acer
Soil (%)
Total rainfall (ml)
III-WL-T-12 13 0,382 NA 2,05 10,00 9 NA 0,322 NA 1,70 5,98 49,5 3180 9,94 28/01/16
III-WL-C-1 1 0,338 NA 2,01 10,05 10 NA 0,353 NA 1,80 9,22 11,9 6 11,67 5/11/15
III-WL-C-2 2 0,304 NA 2,01 9,98 10 NA 0,325 NA 1,88 8,78 21,3 22 13,09 12/11/15
III-WL-C-4 4 0,376 NA 2,02 10,00 9 NA 0,283 NA 1,84 7,96 34,2 801 12,13 26/11/15
III-WL-C-6 6 0,310 NA 1,96 9,96 9 NA 0,316 NA 1,73 7,77 41,3 1041 11,39 10/12/15
III-WL-C-8 8 0,315 NA 2,01 10,02 9 NA 0,308 NA 1,69 7,78 34,5 1181 11,23 24/12/15
III-WL-C-12 13 0,375 NA 1,99 9,98 8 NA 0,351 NA 1,59 6,49 38,8 1960 9,94 28/01/16
III-MP-N-1 1 NA 1,007 2,02 10,07 NA 10 NA 0,869 1,86 9,10 27,0 45 11,24 5/11/15
III-MP-N-2 2 NA 0,591 1,99 10,03 NA 10 NA 0,657 1,84 8,44 45,2 93 12,52 12/11/15
III-MP-N-4 4 NA 1,165 2,01 9,98 NA 10 NA 1,079 1,77 7,37 40,6 1217 11,63 26/11/15
III-MP-N-6 6 NA 0,456 1,94 10,04 NA 10 NA 0,483 1,87 6,97 40,6 1580 10,87 10/12/15
III-MP-N-8 8 NA 0,690 1,99 9,97 NA 10 NA 0,739 1,67 6,13 49,9 1894 10,68 24/12/15
III-MP-N-12 13 NA 0,600 2,01 9,98 NA 10 NA 0,600 1,57 6,99 52,2 2733 9,44 28/01/16
III-MP-M-1 1 NA 0,552 2,08 10,04 NA 10 NA 0,527 1,94 9,01 25,8 13 11,24 5/11/15
III-MP-M-2 2 NA 0,523 2,01 9,95 NA 10 NA 0,525 1,90 8,63 25,0 42 12,52 12/11/15
III-MP-M-4 4 NA 0,896 2,01 9,96 NA 10 NA 0,880 1,80 7,73 28,8 877 11,63 26/11/15
III-MP-M-6 6 NA 0,737 1,91 10,07 NA 10 NA 0,786 1,56 7,13 33,8 914 10,87 10/12/15
III-MP-M-8 8 NA 1,326 2,04 10,04 NA 10 NA 1,407 1,60 6,03 40,6 981 10,68 24/12/15
III-MP-M-12 13 NA 0,816 1,96 10,08 NA 10 NA 0,639 1,57 6,14 58,4 2125 9,44 28/01/16
III-MP-T-1 1 NA 0,741 1,98 10,03 NA 10 NA 0,712 1,86 9,06 25,1 58 11,67 5/11/15
III-MP-T-2 2 NA 0,766 1,96 9,94 NA 10 NA 0,804 1,80 8,45 28,1 132 13,09 12/11/15
III-MP-T-4 4 NA 0,962 2,04 10,06 NA 10 NA 0,784 1,78 8,02 45,6 1036 12,13 26/11/15
III-MP-T-6 6 NA 0,586 2,01 10,01 NA 10 NA 0,587 1,67 7,05 42,2 1526 11,39 10/12/15
III-MP-T-8 8 NA 0,889 1,95 9,97 NA 10 NA 0,701 1,67 6,64 45,0 1991 11,23 24/12/15
III-MP-T-12 13 NA 0,736 2,00 9,98 NA 10 NA 0,730 1,54 5,68 44,5 1736 9,94 28/01/16
III-MP-C-1 1 NA 0,728 2,05 10,04 NA 10 NA 0,516 1,90 9,13 38,9 14 11,67 5/11/15
III-MP-C-2 2 NA 0,858 2,03 10,01 NA 10 NA 0,669 1,82 8,50 39,7 83 13,09 12/11/15
III-MP-C-4 4 NA 0,562 1,96 10,02 NA 10 NA 0,524 1,71 7,87 16,6 819 12,13 26/11/15
III-MP-C-6 6 NA 0,641 1,96 10,02 NA 9 NA 0,584 1,67 7,12 17,8 1096 11,39 10/12/15
III-MP-C-8 8 NA 0,916 1,97 10,08 NA 9 NA 0,682 1,61 6,53 20,5 1169 11,23 24/12/15
III-MP-C-12 13 NA 0,926 1,97 10,02 NA 10 NA 0,929 1,78 5,99 44,3 1865 9,94 28/01/16
III-MX-N-1 1 0,230 0,235 1,98 10,01 5 5 0,243 0,256 1,82 9,10 33,0 54 11,24 5/11/15
III-MX-N-2 2 0,186 0,238 1,96 10,00 1 1 0,027 0,042 1,85 8,71 46,9 98 12,52 12/11/15
III-MX-N-4 4 0,188 0,227 1,98 10,09 5 5 0,199 0,247 1,90 7,52 37,4 1213 11,63 26/11/15
III-MX-N-6 6 0,154 0,170 1,97 9,98 5 5 0,157 0,191 1,61 7,04 53,1 1580 10,87 10/12/15
III-MX-N-8 8 0,168 0,250 2,03 9,98 3 5 0,090 0,265 1,77 7,08 45,8 2117 10,68 24/12/15
III-MX-N-12 13 0,217 0,229 1,96 9,99 5 5 0,221 0,209 1,56 5,40 56,0 3291 9,44 28/01/16
III-MX-M-1 1 0,135 0,175 2,00 10,06 5 5 0,146 0,188 1,88 9,07 19,6 0 11,24 5/11/15
III-MX-M-2 2 0,150 0,184 1,98 10,06 5 5 0,176 0,207 1,84 8,75 23,9 63 12,52 12/11/15
48
Table 3 continued
CODE
Weeks in the field
BEFORE AFTER Moisture
levels
Average Temperature
(°C) DATE
Weight (g) Weight (g) Surviving Weight (g) Weight (g)
WL Total
MP Total Quercus Acer WL MP WL MP Quercus Acer
Soil (%)
Total rainfall (ml)
III-MX-M-4 4 0,157 0,203 1,98 10,02 5 5 0,155 0,216 1,75 7,86 41,2 903 11,63 26/11/15
III-MX-M-6 6 0,126 0,264 1,99 10,02 3 5 0,098 0,280 1,65 7,22 32,4 1197 10,87 10/12/15
III-MX-M-8 8 0,163 0,237 1,98 10,00 5 5 0,188 0,280 1,69 6,67 44,9 1280 10,68 24/12/15
III-MX-M-12 13 0,183 0,223 2,00 10,01 4 5 0,162 0,232 1,66 6,41 46,9 2351 9,44 28/01/16
III-MX-T-1 1 0,201 0,456 2,01 10,00 4 5 0,173 0,478 1,86 8,99 42,6 79 11,67 5/11/15
III-MX-T-2 2 0,181 0,188 2,04 9,98 4 5 0,163 0,201 1,86 8,59 39,0 119 13,09 12/11/15
III-MX-T-4 4 0,243 0,259 2,00 10,04 4 5 0,194 0,290 1,73 7,64 54,9 1123 12,13 26/11/15
III-MX-T-6 6 0,193 0,318 1,98 9,98 5 3 0,255 0,291 1,73 7,00 43,7 1463 11,23 10/12/15
III-MX-T-8 8 0,141 0,487 2,01 9,97 5 5 0,178 0,514 1,69 7,09 35,0 1756 9,94 24/12/15
III-MX-T-12 13 0,180 0,333 2,03 10,00 5 5 0,188 0,369 1,64 6,41 49,5 3180 11,67 28/01/16
III-MX-C-1 1 0,201 0,411 2,02 10,02 5 5 0,226 0,446 1,90 8,92 19,9 0 13,09 5/11/15
III-MX-C-2 2 0,153 0,279 1,96 9,97 4 5 0,130 0,248 1,78 8,46 16,8 10 12,13 12/11/15
III-MX-C-4 4 0,202 0,386 2,03 9,96 4 4 0,186 0,406 1,81 7,69 20,3 819 11,39 26/11/15
III-MX-C-6 6 0,179 0,590 2,00 10,02 5 5 0,192 0,646 1,71 7,24 26,0 1074 11,23 10/12/15
III-MX-C-8 8 0,161 0,522 1,97 9,99 4 5 0,155 0,561 1,66 7,06 40,4 1091 9,94 24/12/15
III-MX-C-12 13 0,133 0,567 1,95 10,02 5 5 0,149 0,608 1,58 5,64 21,9 1863 NA 28/01/16
Legend
CODE Replicate I First replicate
II Second replicate
III Third replicate
Population CO Control group
WL Woodlouse monoculture
MP Millipede monoculture
MX Mixed culture
Treatment N Natural conditions
M Moisture treatment
T Temperature treatment
C Combination treatment
Time Number of weeks in the field