Master’s thesis
Two years
Master by Research in Biology
Effect of experimental warming and assembly history on wood decomposition
Saba Hagos
i
MID SWEDEN UNIVERSITY Dept of Natural Sciences
Examiner: Bengt Gunnar Jonsson, bengt-gunnar.jonsson@miun.se Supervisor: Mattias Edman, mattias.edman@miun.se
Co-supervisor: Fredrik Carlsson, fredrik.carlsson@miun.se Author: Saba Hagos, saha1310@student.miun.se
Degree programme: Master by Researcj, 120 credits Main field of study: Biology
Semester, year: Spring, 2020
i
Master degree thesis in biology Sundsvall 2020
Effect of experimental warming and assembly history on wood decomposition
Saba Hagos
Supervisor:
Mattias Edman, Mid Sweden University Co-supervisor:
Fredrik Carlsson, Mid Sweden University Department of Natural Sciences
Mid Sweden University, SE-851 70 Sundsvall, Sweden
ii
Abstract
Wood decay fungi are the main decomposer of lignocellulose material stored in wood.
Thus, all factors that affect them could affect their ecological function. This in return, may affect ecosystem functioning in terms of altered carbon emissions from dead wood.
Increased temperature is one of the main factors influencing fungal decay. The aim of the current study is to explore the effects of temperature and assembly history (order of species arrival), two important regulators of fungal communities, on wood decomposition. I conducted a microcosm experiment with two temperature treatments and eight assembly histories where each species was allowed to colonize the w ood two weeks ahead of the rest of the species. The temperature treatments were set to mimic the effect of climate induced warming. Therefore, I had one treatment with relatively high temperature, representing the expected temperatures year 2100 given the current emission trends of the northern inland of Sweden, and another treatment representing the current normal temperature (1961-1990). The temperature treatments had an average difference of 5°C. In order to see how climate induced warming and fungal ass embly history influenced decomposition, I measured and analyzed initial fungal growth, fungal respiration and wood weight loss. Both temperature and assembly history had a significant influence on fungal growth, fungal respiration and wood decomposition.
There was also strong interaction between the two factors. The average increase in mass loss under elevated temperature was 19% compared to 14% under normal temperature.
The highest mass loss (25%) was when Phlebia centrifuga was the initial species under elevated temperature and the lowest (12%) was when Climacocystis borealis was initial species under normal temperature. All assembly histories had higher mass loss under elevated temperature, but the magnitude varied. For example, when C. borealis was the initial species, mass loss increased by 60% compared to only 7% when Antrodia sinuosa was the initial species. Six out of eight assembly histories had higher CO2 under elevated temperature, with the highest increase (88%) in P. centrifuga histories and the lowest (7%) in C. borealis histories. Even if the results need to be confirmed by field studies, my data illustrates that climate induced warming probably results in higher fungal respiration and deadwood decomposition and that the magnitude of this effect depends on fungal assembly history.
Key words: wood decay fungi, species composition, assembly history, warming, temperature, fungal growth, decomposition, carbon dioxide, climate feedbacks, species priority, polypore, microcosm, Norway spruce.
Table of contents
Abstract... ii
Introduction ... 1
Materials and methods ... 3
Collection and isolation of fungi ... 3
Wood material and preparation of microcosms ... 4
Manipulation of assembly history ... 4
Temperature treatment ... 5
Measurement of initial mycelial growth ... 6
CO2 measurements ... 6
Wood mass loss calculation ... 6
Data analyses ... 7
Results ... 8
Initial mycelial growth of pre-inoculated species ... 8
CO2 measurements ... 9
Wood weight loss ... 12
Discussion ... 14
Effect of temperature on CO2 production ... 14
Overall CO2 production ... 14
CO2 over time for each assembly history ... 16
The effect of temperature on wood decomposition ... 16
Effect of assembly history on wood decomposition ... 17
Comparison and connection between initial growth of prior species, CO2 produced and wood mass loss ... 17
Conclusions ... 19
Acknowledgment ... 20
References ... 20
Appendix 1a ... 25
Appendix 1b. ... 26
Appendix 1c. ... 27
Appendix 2. ... 28
Appendix 3. ... 31
1
Introduction
Wood decay fungi are important parts of the forest ecosystem as decomposers and as major recyclers of carbon and nutrients (Kauserud et al. 2012). Their ability to efficiently degrade cellulose, hemicelluloses and lignin in wood make them crucial for ecosystem processes (Thygesen et al. 2003; Sánchez 2009). However, growth and survival of wood decay fungi are influenced by both biotic and abiotic factors. Some of the biotic factors include chemical and physical properties of the wood (Edman & Fällström 2013;
Venugopal et al. 2016), invertebrate grazing (Parkinson et al. 1979; A'Bear et al. 2014) and competition with other fungi (Boddy 2000; Carlsson et al. 2014) and bacteria (Frey-Klett et al. 2011). Competition among fungal species in wood is a very intensive and important process (Edman & Eriksson 2016) although the mechanisms involved are quite complicated and not fully understood (Boddy 2000; Hiscox et al. 2016; Hiscox et al. 2017).
Wood decay fungi are very sensitive to changes in their environment. For example, modern forestry has caused extensive habitat loss, which has affected many species of wood decay fungi negatively (Edman et al. 2004; Jonsson et al. 2005). Forest management practices such as clear cutting also lead to an increased solar radiation (Matlack 1993).
This generally increases the temperature and desiccation in dead wood in the clear -cut area and in nearby forest edges, resulting in a significant change in the fungal microenvironment. Some wood decay fungi are affected negatively while others thrive (Siitonen et al. 2005). Further added to the stresses of habitat loss and isolation (Penttilä et al. 2006; Berglund et al. 2011) comes a new threat, global warming, leading to increased temperatures on large scale. According to the climate scenario RCP 8.5 (representative concentration pathway) set by the Intergovernmental Panel for Climate Change (IPCC), which represents comparatively high greenhouse gas emissions, the world temperature will increase by 4.8°C until 2100 (IPCC 2014). RCP 8.5 scenario considers that nations do not make any policy changes to mitigate climate change and greenhouse gas emission will be similar to the present emission levels. In addition it is expected that the increase in temperature will be more pronounced in the boreal zone with up to 6.3 °C for the winter temperatures of the boreal region (Soja et al. 2007). How this will affect wood- decay fungi and decomposition of dead wood is unknown.
There is a growing body of literature indicating that an increased temperature can alter the composition and function of wood decomposer fungi (A‘Bear et al., 2012, A’Bear et al.
2013b and 2014; Toljander et al., 2006; Crowther et al., 2012). For example, Toljander et al., (2006) found that a fluctuating temperature increases species co-existence as well as wood decomposition rates in communities of wood decay fungi. Hiscox et al. 2016 have illustrated change in the competitive ability of some fungi when exposed to increased temperature. Therefore, a climate-induced increase in temperature may potentially change the community structure of wood decomposing fungi, which in turn may affect wood decomposition rates and CO2 production (Hiscox et al. 2015; Allison & Treseder 2011; Van Der Wal et al. 2015). This may increase the risk that the boreal forest floor will turn from a carbon sink to a carbon emission site as the rate of carbon release by
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decomposition might exceed carbon sequestration by photosynthesis (Crowther et al 2016.)
Community structure of wood decomposing fungi is strongly affected by priority effects, i.e. the order of species arrival to a substrate. The presence or absence of one species in a log can influence the subsequent establishment and development of other species. The primary species impose positive or negative impact by modifying the substrate as well as by competitive exclusion of the following species (Lindner et al., 2011; Hiscox et al., 2016; and Ottoson et al., 2014). Therefore, assembly history is an important factor that can alter the community structure and thus affect wood decomposition. Lindner et al. 2011, Fukami et al. 2010, and Dickie et al. 2012). Thus, a climate-induced change in temperature could potentially affect initial decomposers differently, thereby influencing the effect of assembly history.
Both the effect of increased temperature due to global warming and fungal assembly history have received much attention in ecological studies recently (Clements et al. 2013).
However, the results are quite varied and thus further research is needed to understand how these two factors affect wood decaying fungi and interact with each other .
Here, I try to evaluate the effect of both increased temperature and fungal assembly history, as well as their interactive effect on wood decomposition. I address this through a laboratory experiment using eight different wood fungi species grown on wood discs under different temperature regimes. I hypothesize that: a) even a moderate increase in temperature will result in increased wood decomposition, b) different initial species will lead to different decomposition rates as growth rate and competitive ability differ between fungal species, c) there may be an interaction between assembly history and temperature. For example, an initial colonizer with higher temperature optima is expected to be more successful with greater influence on the fungal community structure under elevated temperatures compared to under normal temperatures, which may be reflected in the decomposition rate.
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Materials and methods
Collection and isolation of fungi
Fruiting bodies of eight wood decay fungi were collected from forests located in different parts of mid boreal Sweden in Autumn 2014 (Table 1). Pure cultures of the species were obtained using either Hagem media or a selective Hagem medium containing thiabendazole (230mg/l) and benomyl (2g/l). We isolated eight strains per species, except for Antrodia xantha, Climacocystis borealis and Phlebia centrifuga for which we only were able to find 5, 7 and 6 strains, respectively (Table 1). The species chosen represent a variety of habitat preferences; Fomitopsis rosea, Phellinus ferrugineofuscus and Phlebia centrifuga are all confined to old spruce wood in this region and are predominantly found in fairly moist old growth forests with a closed canopy and relatively cold microclimate (Karström, 1993). Antrodia sinuosa and A. xantha, on the other hand, are predominantly found in open and dry pine dominated forests with a warmer microclimate, although they sometimes occur in spruce forests as well. Gloeophyllum sepiarium is known to have a very high temperature optimum 27.5-32.5°C (Schmidt, 2006) and thrive especially on spruce wood in open, sun exposed habitats such as clear cuts. Climacocystis borealis is confined to large spruce trees and the heartwood is colonized already while the tree is living; when the tree falls or are cut the fungus continues as a saprotroph in the stumps.
Finally, Fomitopsis pinicola is a very common generalist species found in most forest habitats, including clear cuts. The selected species also represent various functional traits such as different rot types (white- and brown rot) and preferred decomposition stage of the wood (Table 1). However, all species are able to colonize and decay fresh spruce wood, which were also confirmed by growing them on fresh wood disks before running the experiment.
Table 1 . Species used in the study, type of rot and their preferred decay stages as indicated by occurrence of fruiting bodies on natural logs (Renvall, 1995). Decay stages 1-5 indicate the average decay stage of the wood; where stage 1 represent fresh wood and stage 5 very decayed wood.
Scientific name Abbreviations Rot type Average decay stage
No. of strains
Antrodia sinuosa AS Brown rot 2.8 8
Antrodia xantha AX Brown rot 2.6 5
Climacocystis borealis CB Brown rot 2.4 7
Fomitopsis pinicola FP Brown rot 2.6 8
Fomitopsis rosea FR Brown rot 2.8 8
Gloeophyllum sepiarium GS Brown rot 2.4 8
Phlebia centrifuga PC White rot 2.4 6
Phellinus ferrugineofuscus PF White rot 2.7 8
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Wood material and preparation of microcosms
Three healthy Norway spruce trees (Picea abies L. Karst.) with a base diameter of about 9 cm were collected and cut into 1 cm thick and approximately 8 cm diameter wood disks.
The wood discs were oven dried at 40 °C for 5 days and thereafter their dry weight was recorded. During the drying of wood discs their change in weight was followed and they were considered as completely dry after the change in weight levelled out. They were then wetted by soaking them in water over night and sterilized 3 times at 121 °C for 15 min. The wood discs were placed in 500 ml glass jars containing 110 ml of perlite wetted with 65 ml water to sustain a high and stable humidity in the jars. The jars were sterilized with their lids on but after the inoculation of the first species the lids were removed and the jars where instead covered by 10cm wide para film to allow gas exchange.
Manipulation of assembly history
The fungal species were grown for two weeks on Hagem media plates before transferring an eight 8 mm diameter plug with the fungi onto the wood discs. Assembly history treatment was created by letting one species establish before the rest of the species. This was done by inoculating the initial species two weeks before the other species (Fig. 1). From two weeks old cultures, agar plugs, one from each species, were removed and inoculated at pre-determined, standardized locations on all replicates (Fig.
1). Thus, the relative position of the eight species was identical for all samples, and each fungal species was allowed to be inoculated first. In all replicates different strains were used but a few strains were used twice due to shortage of available strains (Table 1). All treatments were replicated eight times.
Fig.1 a representative example of the priority treatments after two weeks with Antrodia sinuosa as prior species in the normal temperature cabinet (12°c) on the left and
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elevated temperature cabinet (17°c) on the right. the other seven species have just been added abbreviations as in table 1. photo by Mattias Edman, illustration Saba Hagos
Temperature treatment
To represent the normal and elevated temperatures I used two climate cabinets (Termaks 6000 cooling incubator) set on two different temperatures. The normal (colder) temperature treatment was based on the average monthly temperature during the period 1961-1990 for the northern inland of Sweden (SMHI) and the predicted elevated temperature was based on the RCP 8.5 scenario temperatures for 1991-2100 for the same region (SMHI). RCP 8.5 is a scenario of comparatively high greenhouse gas emissions, an emission closest to the currently measured emission trends. According to this scenario it is predicted that the average monthly temperature 1991-2100 will increase by 4-6 °C compared to period 1961-1990 in the northern inland of Sweden.
The average monthly temperatures data was extracted from the home page of the Swedish Meteorological and Hydrological Institute (SMHI). Average monthly temperatures of years 1961-1990, which had an average temperature above 0°C were used with their corresponding scenario temperatures as treatment (Table 2). Hence, the colder months, which are November, December, January, February and March were excluded.
The starting temperature treatment was August month’s temperature, because many fungal species start to produce fruiting bodies, release spores and colonize new substrates at this time of the year. The treatment then continued with temperatures of September, October, April, May June and July. August and September temperature treatments were repeated in the end to give enough time for wood decomposition to take place. Hence, there were nine temperature cycles in total. Each temperature cycle was run for 30 ±5 days, except for the first temperature cycle which had two weeks extra during the growth of the priority species.
Table 2.Temperature treatments of the represented months showing the average monthly temperatures used. The normal temperatures are based on the observed temperature in mid boreal Sweden during 1961-1990 and the elevated temperatures are based on the RCP 8.5 scenario of the years 1991-2100 in the same region.
Months Normal temperature Elevated temperature
August 12 17
September 8 14
October 4 10
April 0 6
May 7 13
June 12 17
July 13 18
August 12 17
September 8 14
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Measurement of initial mycelial growth
To determine the response of individual species to increased temperature I measured the growth of the initial species during the first two weeks. Mycelial growth was measured as the radial extension (mm) from the edge of the agar plug towards the center of the wood disc. The temperature treatment during this period was that of August month´s temperatures 12°C and 17 °C, for the normal and elevated temperature respectively.
There was a five degrees difference between the two temperature treatments at this point.
CO2 measurements
Since carbon dioxide is released as a result of wood decomposition, the amount of carbon dioxide released can be used as a proxy for the wood decomposition rate at a specific moment in time. Here, I estimated the decomposition rate of the wood discs by measuring the CO2 accumulated in the jars during one hour. The Maximum CO2 accumulated was measured using EGM-4 Environmental Gas Monitor. Carbon dioxide measurements were taken once a month for the last six months of the experiment. The temperatures represented here are monthly temperatures of April, May, June, July, August and September. Carbon dioxide measurement was taken at the end of each monthly temperature treatment. Jars containing wood disks where ventilated under sterile conditions in a laminar flow cabinet for 5 minutes in the same temperature as the temperature treatment itself. They were then incubated in the climate cabinets for a period of time to accumulate CO2, which was then measured by injecting 10 mm gas samples into the EGM-4 gas analyzer. Since the EGM-4 has an upper and lower ppm detection limit, we needed to adjust the time of incubation to avoid saturation of the EGM-4 or come up to lowest detectable concentration. The appropriate incubation time was tested and adjusted before each measurement occasion to avoid inhibiting effects resulting from CO2 saturation in the jars. The incubation time when the jars were closed to accumulate CO2 after ventilation was 12 hrs., 6 hrs. and 40 minutes in the first, second and the last four measurements respectively. The EGM-4 gas analyzer had a maximum of 10000 PPM which the trial measurements have exceeded many times thus the incubation time was adjusted to solve this.
Wood mass loss calculation
The weight loss of the wood disks was calculated at the end of the experiment by drying the wood discs in a drying chamber at 40 °C for 5 days. After five days the weight had stabilized. Prior to drying saw dust samples were taken from the discs for molecular analysis of fungal species composition. Twenty-four drill samples of saw dust where taken from each wood disc using 4mm diameter drills. The molecular analysis is not included in the thesis work. The wet weight of the saw dust samples as well as of the drilled wood disc were recorded during sampling. After drying the drilled wood discs their weight was recorded. The wet weight of saw dust samples, wet weight of drilled wood discs and the dry weight of the drilled wood discs were used for calculating the
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dry weight of saw dust samples as given below. The dry weight of the saw dust was then used to calculate the dry weight of the whole wood disc after decomposition.
𝐷𝑟𝑦 𝑤𝑡 𝑜𝑓 𝑠𝑎𝑤 𝑑𝑢𝑠𝑡 𝑠𝑎𝑚𝑝𝑙𝑒 =𝐷𝑟𝑦 𝑤𝑡 𝑜𝑓 𝑑𝑟𝑖𝑙𝑙𝑒𝑑 𝑤𝑜𝑜𝑑 𝑑𝑖𝑠𝑐 ∗ 𝑤𝑒𝑡 𝑤𝑡 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑎𝑤 𝑑𝑢𝑠𝑡 𝑠𝑎𝑚𝑝𝑙𝑒 𝑊𝑒𝑡 𝑤𝑡 𝑜𝑓 𝑑𝑟𝑖𝑙𝑙𝑒𝑑 𝑤𝑜𝑜𝑑 𝑑𝑖𝑠𝑐𝑠
The dry weight of the whole wood disc after decomposition was calculated as the sum of the dry weight of drilled disc plus the calculated dry weight of the saw dust. The dry weight of the saw dust was on average 1.1g, representing 7.6% of the total dry wt. Having calculated the dry weight of the whole wood disk, it was straight forward to calculate the percentage wood weight loss by:
𝑊𝑒𝑖𝑔ℎ𝑡 𝑙𝑜𝑠𝑠 (%) = (𝐼𝑛𝑖𝑡𝑖𝑎𝑙 𝑑𝑟𝑦 𝑤𝑡 − 𝐹𝑖𝑛𝑎𝑙 𝑑𝑟𝑦 𝑤𝑡
𝐼𝑛𝑖𝑡𝑖𝑎𝑙 𝑑𝑟𝑦 𝑤𝑡 ) ∗ 100
Data analyses
The effect temperature and assembly history on wood mass loss and initial mycelial extension rate was analyzed with two-way ANOVAs. Temperature and initial species were treated as fixed factors. CO2 data was analyzed in the same way, except that a repeated measures term was also added since monthly CO2 data were used. Wood mass loss data was arcsines square root transformed and mycelial extension data and CO2 data log transformed to meet the assumptions of ANOVA. All ANOVAs were performed in SPSS (IBM Statistics for Windows, version 22.0. Armonk NY: IBM corp.)
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Results
Initial mycelial growth of pre-inoculated species
All species showed a higher radial mycelial growth in the elevated temperature than the normal one. The total average growth of all species was doubled in the elevated temperature compared to in the normal (Fig. 2). Phlebia centrifuga was the one showing the fastest growth in both normal and elevated temperatures, while C. borealis had lowest growth rate of all species under the elevated temperature. Gloeophyllum sepiarium had the lowest growth in normal temperature followed by C. borealis. Even if all species responded positively to an increased temperature, some species were more favored than others. For example, the growth of F. pinicola increased by fourfold (315%) while Phellinus ferrugineofuscus nearly doubled (68%) its growth rate (Fig. 2). The difference in species response to increased temperature is also indicated by the significant interaction between initial species identity and temperature from the two-way ANOVA on mycelial growth data (Table 3).
Fig.2 Initial radial mycelial extension in mm (mean ± SE, n = 8) of initial species after two weeks growth. Darker bars show growth under the elevated temperature and lighter bars normal temperature. This growth was recorded during the August temperature treatment (17°C elevated 12°C normal temperature). The relative
difference in growth (%) between elevated and normal temperature is indicated above bars.
185
103
98
315
141 183
70
68
0 5 10 15 20 25 30 35
radial mycelial growth (mm )
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Table 3 Results of a two-way ANOVA with initial fungal growth rate of pre-inoculated fungi as dependent variable and temperature and species as factors. Initial growth rate was measured two weeks after inoculation, expressed as the radial extension (mm) from the edge of the agar inoculum towards the center of the wood disc. Temperature was emulating normal (+12°C) and expected elevated (+17°C) average temperatures in August.
Source Type III
Sum of Squares
df Mean
square
F P-value
Temperature 4.32 1 4.32 204.57 0.000
Species 2.46 7 0.35 16.62 0.000
Temp x Species 0.54 7 0.08 3.67 0.001
Error 2.36 112 0.02
CO2 measurements
The repeated measures GLM with accumulated CO2 per hour as dependent variable and temperature and assembly history as factors showed a strong effect of temperature, assembly history and their interaction (Table 4). Six of the eight assembly histories had higher CO2 production at elevated temperature (Fig. 3). Assembly histories with F.
pinicola and P. centrifuga as initial species doubled their CO2 production at elevated temperature, i.e. an increase of 84% and 87%, respectively, while histories initiated by C.
borealis, F. rosea, G. sepiarium and P. ferrugineofuscus increased only slightly, i.e. 7%, 10%, 30% and 19% respectively (Fig 3). In contrast, assembly histories initiated by A. sinuosa and A. xantha decreased their CO2 production by 41% and 16%, respectively, under elevated temperature compared to normal temperature.
Table 4 Results of a repeated measures GLM with accumulated CO2 per hour as dependent variable and temperature and assembly history as factors. CO2 was measured once a month the last six months of the experiment, representing the average temperatures of April to September.
Source Type III
Sum of Squares
df Mean
square
F P-value
Temperature 2.34 1 2.34 26.13 0.000
Assembly history 1.10 7 0.16 2.38 0.026
Temp x History 1.9 7 0.27 4.01 0.000
Error 7.4 112 0.07
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Fig. 3 Average CO2 production in ppm/hr (mean ±SE, n = 8) of all six temperature measurements in elevated temperatures (black) and normal (grey), during the last six months of the experiment, (April to September temperatures) with initial species indicated below the bar graphs.
The relative difference in CO2 production (%) between elevated and normal temperatures are indicated. The first peak in CO2 accumulation occurred in June temperatures, which was 12 and 17 C in the lower and higher temperature treatment, respectively. This measurement was taken six months after the start of the experiment.
Although the highest temperature treatment was that of July, CO2 production was highest in June temperature. The pattern in CO2 production was fairly similar over assembly histories in the beginning of the experiment, i.e. April, May, June and July temperatures, thereafter the CO2 evolution was quite varied (Fig. 4). Carbon dioxide release started low during April month’s temperature, increased a bit in May’s temperature and then peaked during the June temperature treatment. The only exception to this was the lower temperature treatment of C. borealis which peaked later during July’s temperature treatment. The CO2 production at normal temperature was lower than at elevated temperature up to the third measurement for almost all (six out of eight) assembly histories. But after the third measurement (June’s temperature), the CO2 release varied. It went down again during July or August temperatures and peaked again in September’s temperature for almost all assembly histories in both temperatures.
0 1000 2000 3000 4000 5000 6000 7000
A. sinuosa A. xantha C. borealis F. pinicola F. rosea G. sepiarium P. centrifuga P. furrugineofuscus
CO
2p rodu ction in p p m /h r
7
84 10
30
88 -41 -16 19
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Fig 4. Carbon dioxide in ppm/hr (mean ± SE, n = 8) produced during the six
measurement events for the assembly history treatments of A. sinuosa, A. xantha, C.
borealis, F. pinicola, F. rosea, G. sepiarium, P. centrifuga, and P. ferrugineofuscus. Lines shows the measurements during the different monthly temperature treatments at elevated (black) and normal (grey) temperature treatments.
0 2000 4000 6000 8000 10000 12000 14000
A. sinuosa
0 2000 4000 6000 8000 10000 12000 14000
C. borealis
0 2000 4000 6000 8000 10000 12000 14000
A. xantha
0 2000 4000 6000 8000 10000 12000 14000
F. pinicola
0 2000 4000 6000 8000 10000 12000 14000
G. sepiarium
0 2000 4000 6000 8000 10000 12000 14000
F. rosea
0 2000 4000 6000 8000 10000 12000 14000
P. centrifuga
0 2000 4000 6000 8000 10000 12000 14000
P. ferrugineofuscus
CO
2P ro d u ct io n p p m /h r
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Wood weight loss
There was a clear effect of both temperature and assembly history on wood mass loss.
The highest mass loss (25%) occurred under elevated temperature when P. centrifuga was the initial species and the lowest (12%) in the normal temperature treatment when C.
borealis was the initial species. The average mass loss under elevated temperature species was 19% compared to 14% in normal temperature, representing 36% increase in mass loss under elevated temperature. The priority of some species, such as C. borealis, resulted in a large difference in mass loss between elevated and normal temperature, while in other species, such as A. sinuosa, the difference was minimal or rather non-significant (Fig. 5).
Analysis of variance (ANOVA) of wood mass loss data showed that both temperature and assembly history have strong effect on wood decomposition. Although temperature seem to have slightly higher effect compared to assembly history, the effects of these factors are clearly not independent of each other. This is indicated by the significant interaction between them (Table 4). The effect of assembly history is modified by the effect of temperature, for example the difference in wood weight loss betwee n elevated and normal temperature is much larger than the difference in weight loss between the different assembly histories of the same temperature
Fig. 5 Percentage wood mass loss under elevated (black) and normal (grey) tempe rature treatments, pre-inoculated species are indicated under the bars. The increases in mass loss (%) between normal and elevated temperatures are shown above bars.
7
28 60
18
29 36
57
47
0 5 10 15 20 25 30
A. sinuosa A. xantha C. borealis F. pinicola F. rosea G. sepiarium P. centrifuga P. ferrugineofuscus
Wood mass loss (%)
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Table 3 Results of a two-way ANOVA with wood mass loss as dependent variable and temperature and assembly history as factors.
Source Type III
Sum of Squares
df Mean
square
F P-value
Temperature 0.07 1 0.07 47.25 0.000
Assembly history 0.04 7 0.01 3.85 0.001
Temp x History 0.02 7 0.00 2.24 0.036
Error 0.17 112 0.00
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Discussion
Temperature had a strong direct effect on mycelial growth, CO2 release and wood decomposition. Increased temperatures stimulated mycelial growth and increased overall carbon dioxide production and wood decomposition. By changing the mycelial growth of initial species, increased temperature altered fungal interactions, thus indirectly influencing CO2 production and mass loss. Thus, temperature modified the effect of assembly history. The direct positive effect of temperature on wood decomposition is well established (Kauserud 2012; Venugopal et al. 2016 and 2017;
Crowther et al. 2012). In line with my results, there is also a growing body of research showing the effect of assembly history on wood decomposition and function of wood decaying fungi (Dickie et al. 2012; Fukami et al. 2010; Hiscox et al., 2016 and Ottoson et al., 2013). However, to the best of my knowledge I am the first to show that temperature indirectly influences decomposition rates by modifying the effect of assembly history.
Effect of temperature on CO2 production
Overall CO2 production
Carbon dioxide production was generally higher at elevated temperature compared to normal temperature treatments. However, when A. sinuosa and A. xantha were introduced first there was higher CO2 production at normal temperatures. This is because temperature is not the only factor influencing the results; there is also an effect of species interactions, which in turn are influenced by assembly history. Thus, this could be one reason that assembly histories of Antrodia species showed a different result. In addition, since the two species belong to the same genera they might behave similarly in many aspects, such as growth and competition strategies (Boddy and Hiscox, 2016). For example, both were good at occupying new territory. In addition, I observed that both species had faster growth in the beginning of the experiment with more mycelial cover in the higher temperature. In most replicates, they were growing extensively with a scavenging or foraging style but did not seem to use much of the wood resource. Antrodia sinuosa formed mycelial cords and seemed to use the nutrients in the agar plugs of other species in the same wood disc (Appendix 1a and b) when it was the prior species. In the case of A. xantha mycelial cover was almost the same in elevated and normal temperature when it was prior species. This could be the reason why there was no significant difference in CO2 production between elevated and normal temperature of A. xantha priority histories. The slightly higher CO2 production in the normal temperature may be associated with some of the other species being dominant at lower temperature. For example, in one replicate P. centrifuga covered the whole wood piece (Appendix 1C).
Alternatively, since both Antrodia species have high temperature optima for growth, i.e.
27.5 - 31°C for A. xantha and 24-31°C for A. sinuosa (Schmidt, 2005), the temperature
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treatment of the first month (12°C and 17°C for the normal and elevated temperature treatment, respectively), may not have been high enough to give them the advantage of being the prior species, which may cause a longer competition phase.
The highest CO2 production occurred when P. centrifuga was the initial species at elevated temperature and the lowest when F. pinicola was the initial species at normal temperature. Assembly histories formed with these two species as prior species were also the ones which showed the biggest difference in CO2 produced between elevated and normal temperatures (Fig. 3). Even if P. centrifuga is more common in northern part of Sweden, northeastern Europe and north America (Artfakta; SLU) and thus considered northern species with colder climate preference, its success at the elevated temperature could be associated with its initial fast growth. In addition, the wood type and high moisture content might have favored it in comparison to other species and thus the CO2 produced is attributed to its abundance. Carbon dioxide production are affected by factors like humidity and substrate quality (Venugopal et al. 2016). This species prefers wet spruce wood and is common in wet spruce forest, which resembles the environment in our experimental setting (quite high moisture content and spruce as wood type) . This potentially gave the species an advantage over other species. Phlebia centrifuga was also favored by its capacity to outcompete other fungi, and it was usually the only species left in both elevated and normal temperatures when introduced first (Appendix 2). In addition, it was often dominating even when it was not the initial species.
Even if assemblies initiated by F. pinicola also had high CO2 production in elevated temperature,this was not connected with the presence of the initial species itself, but rather with the presence of A. sinuosa which showed very strong competitive ability, especially against F. pinicola. Antrodia sinuosa was highly competitive at elevated temperature and managed to gain more than half of the wood surface already when one third of the experimental period remained. I believe this increase in CO2 production is connected with A. sinuosa, as it won the competition early (Appendix 3) and was the only species left at the end of the experiment. In the lower temperature of the same assembly history, A. sinuosa was not winning as easily and therefore more species persisted, which seemed to slow down the decomposition process. In a study by Hiscox et al.(2015b), CO2 increased only after one species has replaced the other species in a pairwise competition, showing that when fungi compete they invest their resources in interactions instead of decaying wood. My findings seem to agree with this, as less carbon dioxide was produced when many species were present in the wood discs (see Fig.3 and Appendix 3).
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CO2 over time for each assembly history
The CO2 production varied greatly over time. The first peak in June temperature could be associated with the fact that it was the first warm temperature after the fungi ha d established on the wood substrate, and there were still a lot of easily accessible resources left to exploit. When C. borealis was prior species the peak in the normal temperature came later, in July’s temperature treatment. The reason could be that there were many species in those wood discs and they were first engaged in competition. This may have reduced decomposition in the early period, with increasing decomposition later on when some species had gained more space. Somewhat surprisingly, CO2 production increased again for all assembly histories in September’s temperature, which was the last measurement. The reason for this may be that the most intense competition phase had ended for almost all assembly histories, especially at elevated temperature, and resources were instead used for decomposition.
The effect of temperature on wood decomposition
Wood weight loss was 36% higher in elevated temperature compared to in normal temperate. Almost all assembly treatments had higher wood weight loss unde r elevated temperature, except for the assembly history A. sinuosa, where the difference was very small or non-significant. The positive relationship between increased temperature and decomposition is well established. Venugopal et al. (2016) demonstrated that temperature is the most important factor affecting decomposition besides substrate quality. Rinne- Garmston et al. (2019) also support the finding presented here. Rubenstein et al (2017) showed that an increase in temperature will result in higher wood decomposition, but also highlighted the importance of species prior exposure to higher temperature. Species that have been exposed to higher temperatures previously, decay the wood faster than those that have not.
Even if we did not pre-expose the species to higher temperatures in this experiment, species that are reported to like a relatively higher temperature did succeed in winning larger surface area. For example, A. sinuosa won at elevated temperature when it was the prior species and when weak competitors such as F. pinicola and F. rosea were introduced first. What is more interesting is that an elevated temperature resulted in higher wood weight loss when the prior species were white rot fungi. The highest wood weight losses in elevated temperature were caused by the white rot fungi P. centrifuga and P.
ferrugineofuscus. An increase in temperature might increase decomposition by both altering the enzymatic activity of fungi (A'Bear et al. 2014) and by changing the structure of the decomposer community.
Even if increase in temperature in general implied better initial growth and faster wood decomposition, the strength in response to elevated temperature varied between assembly histories. For example, the effect of elevated temperature was minimal with an increase of only 7 % in assembly history of A. sinuosa but the assembly history of C.
borealis was as high as 60 %. Such large variation in decomposition under warming is
17
clearly important to consider when modelling forest carbon budgets. However, it is important to note that this is under laboratory conditions, and it needs to further study if the result applies to natural systems. According to Crowther et al. (2017), there is a risk that the rate of carbon release to the atmosphere due to decomposition of organic matter will be greater than the carbon sequestration by photosynthesis. Thus, converting the boreal forest floors from a carbon sink to a carbon emission site, resulting in increased temperature and a feedback to global warming.
Effect of assembly history on wood decomposition
Assembly histories strongly influenced wood decomposition. The assembly history with P. centrifuga as prior species caused the highest wood mass loss at both elevated and normal temperature treatments, while the lowest mass loss was caused by C. borealis histories under normal temperature. Fungal species vary in their nutrient utilization, growth rate and combative ability, resulting in different community development and decomposition for different assembly histories (Fukami et al., 2010; Linder et al. 2011;
Hiscox et al 2016 and Ottoson et al. 2013). Some fungi might have a common system for nutrient utilization and/or defense mechanisms and therefore we see similarities in the behavior of some fungal groups. For example, the white rot fungi P. centrifuga and P.
ferrugineofuscus caused the highest mass loss in elevated temperature, which might be connected with their fast growth rate. However, wood mass loss can be affected by many other factors than species individual growth, such as host tree preference, wood moisture and the specific strategy that each species use to degrade wood and obtain nutrients. For example, white rot fungi have the advantage of degrading all three components (lignin, cellulose and hemicellulose), which possibly may result in higher wood decay rates.
However, wood weight loss was also different between species within the same decay category, indicating that assembly history itself contributes to differences in mass loss and decay communities. This signifies the importance of species priority on species composition, which in return has big influence on wood decomposition (e.g.Venugopal et al. 2017). Difference in wood mass loss between assembly histories was more visible at elevated temperature compared to normal temperature. This suggests that higher temperature treatment escalates the difference established by different assembly histories.
Comparison and connection between initial growth of prior species, CO2 produced and wood mass loss
The initial mycelial growth and CO2 production of the respective assembly histories followed a similar pattern (see figures 2 and 4). For example, F. pinicola and P. centrifuga histories produced most CO2 in both measurements at elevated temperatures. After them followed F. rosea and P. ferrugineofuscus with high CO2 production in both measurements, and then followed G. sepiarium. In addition, all of them had higher initial growth and carbon production at elevated temperatures and a relatively low initial growth and carbon production at normal temperatures. An exception to this pattern was that of Antrodia species, whose initial mycelial growth was higher in elevated temperature,
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while CO2 production pattern was higher in normal temperature. In comparison, there is no such similar pattern between CO2 production and wood mass loss, except that of P.
centrifuga and P. ferrugineofuscus. Even if the magnitude of the measured CO2 and wood mass loss differed between the assembly histories, they generally produced more CO2 at elevated temperatures compared to under normal temperatures. This shows clearly that assembly history, which alters competitive outcomes and community structure, result in somewhat different pattern in mass loss compared to estimates of CO2 production. This finding is also coherent with the result of (Hiscox et al. 2015a) that found that antagonistic fungal interactions influence CO2 evolution from a decaying wood. Temporal patterns of CO2 release from wood and the final wood mass loss are two different estimates of wood decay. CO2 measures reveal the temporary fungal mediated wood decay and is affected by the community composition at that specific time point, while wood mass loss measures the fungal wood decomposition over the whole experimental period.
This research has revealed the fact that mycelial growth, competition and wood mass loss are related. However, fast mycelial growth does not by default mean success in competition. Carbon dioxide measurement is a good estimate of wood decay over time and a good complement, but should not be used as a substitute for wood mass loss. It may be appropriate to use CO2 production to estimate decomposition by single fungi, but not when there are many species involved, as it may be affected by fungal competition. Since fungal competition is metabolically costly and the CO2 release may vary from time to time with the competition phase, the species contributing most to decomposition may vary from time to time. Initial mycelial growth, CO2 production and wood mass loss data for the assembly histories of P. centrifuga and P. ferrugineofuscus are consistent, G. sepiarium CO2 production and wood mass loss are also consistent. This is an example were one species dominates or the priority species dominates and acts as a single species composition by being the most influential species. But this does not apply were there the priority effect is altered by competition outcomes.
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Conclusion
This research show that abiotic factors such as temperature have a tremendous effect on the growth and competitive ability of fungi and even a moderate increase in temperature (about 5 °C) can result in as high as 36% increase in the wood mass loss. Increase in temperature has shown to influence the community composition by favoring certain species involved in forming the fungal community. In addition, this study has shown that fungal assembly history is very important in forming fungal communities. Different fungal communities are developed depending which fungal species arrives first to a piece of wood. This study has also shown that higher temperature due to global warming speeds up wood decomposition and carbon recycling. This is an example of what would happen in the boreal region such as the northern inland of Sweden. But this could be applicable to most of the boreal zone forests that are expecting an equivalent rise in temperature. Higher fungal respiration as observed in the elevated temperature in our experiment means faster depletion of organic matter from the forest floor and higher CO2 to the atmosphere. Both temperature and assembly history are very important factors in forming a unique community. Wood decomposition involves complex physical and chemical interactions among wood decaying fungi and therefore it would be interesting to look further into these interactions and do analytical test on fungal products in the lab.
But also carry out field studies in order see how global warming influence fungal diversity and CO2 feed-backs to the atmosphere. Better understanding of fungal community ecology might help us to understand how to conserve biodiversity and how to manage our forests with better respect for complex ecological communities that exist in the forest. If we learn how complex natural communities are, we can have a good guess how difficult it could be to restore a complex system. Then maybe we will leave these systems untouched or do our best to conserve them and make more efforts to reduce human made environmental deterioration.
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Acknowledgments
I thank God for giving me all the nice people who are around me! I would like to thank Lennart for letting me and my husband know that there is a University at Sundsvall and that there is a biology department at the University and for the time we spent with him and his wife at Matfors. I am very thankful for Viktoria and Veronica for opening the door of Mid Sweden University and letting me and my husband meet Bege the first time we came to Campus Sundsvall. Håkan and Torborg for being always available, being helpful and very friendly, you make it easier for me and others who are working here.
Joel Ljunggren for being my guider in the project we worked together and for teaching me a lot and above all for the excel tricks and formula that make big work smaller and save a lot of time in my work. But not only that you are more than that, as I said before you are my brother. Would also like to thank all my colleagues and friends From Mid Sweden University. Jenny Sandström for motivating me when I was making my first poster that I made for the MBr day, for the nice times we spent in the field work in your project and tea and coffee festivity in your cottage and home and for the nice talk. Sara Öhmark for the nice time we spent together here at the university, at your home and for the field trips and for visiting me the very special day. I would like to thank Dan Bylund, Erik Hedenström and Bengt-Gunnar Jonsson for the employments that I have had in the department. I am also thankful for all the friendship and care and help that I got from all members of department of chemistry, administration, It and janitors office. I would to thank those who have more contribution to the thesis work my Supervisor Mattias Edman, I am so thankful for your guidance throughout the work and for photo documentation of the work and for being so patient and friendly. I would not have made it all the way if you have not been very supportive even in my daily life. My co-supervisor Fredrik Carlson for your kind guidance and for being so cheerful and friendly. Bengt - Gunnar Jonsson for your useful comments as the thesis develops from beginning to the end and for all the help I got from you and for the bio grill. I am so thankful for the help I got in field work from Jonas Orelund and Mattias Edman, and the laboratory work help from Irin, Emely, Yingue, and Lin. Lastly, I like to thanks our son Nathan for being so patient the times I worked in the lab and for lending me his holidays and weekends. My husband Fitsumberhan for showing care and giving me time to work with my thesis and for being supportive all the time.
Thanks God!
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References
A'Bear, A.D., Jones, T.H. & Boddy, L. (2014). Potential impacts of climate change on interactions among saprotrophic cord-forming fungal mycelia and grazing soil invertebrates. Fungal Ecology, 10, 34-43.
A'Bear, A.D., Boddy, L. & Hefin Jones, T. (2012). Impacts of elevated temperature on the growth and functioning of decomposer fungi are influenced by grazing collembola. 18, 1823-1832.
Allison, S.D. & Treseder, K.K. (2011). Climate change feedbacks to microbial decomposition in boreal soils. Fungal Ecology, 4, 362-374.
Berglund, H., Hottola, J., Penttilä, R. & Siitonen, J. (2011). Linking substrate and habitat requirements of wood-inhabiting fungi to their regional extinction vulnerability.
34, 864-875.
Boddy, L. (2000). Interspecific combative interactions between wood-decaying basidiomycetes. FEMS Microbiol Ecol, 31, 185-194.
Carlsson, F., Edman, M., Holm, S. & Jonsson, B.-G. (2014). Effect of heat on interspecific competition in saprotrophic wood fungi. Fungal Ecology, 11, 100-106.
Carlsson, F., Edman, M. & Jonsson, B.G. (2017). Increased CO2 evolution caused by heat treatment in wood-decaying fungi. Mycological Progress, 16, 513-519.
Clements, C.F., Warren, P.H., Collen, B., Blackburn, T., Worsfold, N. & Petchey, O.
(2013). Interactions between assembly order and temperature can alter both short- and long-term community composition. Ecology and evolution, 3, 5201-5208 Crowther, T.W., Littleboy, A., Jones, T.H. & Boddy, L. (2012). Interactive effects of
warming and invertebrate grazing on the outcomes of competitive fungal interactions. FEMS Microbiol Ecol, 81, 419-426.
Crowther, T.W., Todd-Brown, K.E.O., Rowe, C.W., Wieder, W.R., Carey, J.C.,
Machmuller, M.B. et al. (2016). Quantifying global soil carbon losses in response to warming. Nature, 540, 104
Dickie, I.A., Fukami, T., Wilkie, J.P., Allen, R.B. & Buchanan, P.K. (2012). Do assembly history effects attenuate from species to ecosystem properties? A field test with wood-inhabiting fungi. Ecol Lett, 15, 133-141.
Edman, M. & Eriksson, A.-M. (2016). Competitive outcomes between wood-decaying fungi are altered in burnt wood. FEMS Microbiology Ecology, 92, fiw068-fiw068
22
Edman, M. & Fällström, I. (2013). An introduced tree species alters the assemblage structure and functional composition of wood-decaying fungi in microcosms.
Forest Ecology and Management, 306, 9-14.
Edman, M., Gustafsson, M., Stenlid, J. & Ericson, L. (2004). Abundance and viability of fungal spores along a forestry gradient – responses to habitat loss and isolation?
, 104, 35-42.
Frey-Klett, P., Burlinson, P., Deveau, A., Barret, M., Tarkka, M. & Sarniguet, A. (2011).
Bacterial-Fungal Interactions: Hyphens between Agricultural, Clinical, Environmental, and Food Microbiologists. Microbiology and Molecular Biology Reviews : MMBR, 75, 583-609.
Fukami, T., Dickie, I.A., Paula Wilkie, J., Paulus, B.C., Park, D., Roberts, A. et al. (2010).
Assembly history dictates ecosystem functioning: evidence from wood decomposer communities. Ecology Letters, 13, 675-684.
Hiscox, J., Clarkson, G., Savoury, M., Powell, G., Savva, I., Lloyd, M. et al. (2016).
Effects of pre-colonisation and temperature on interspecific fungal interactions in wood. Fungal Ecology, 21, 32-42.
Hiscox, J., Savoury, M., Toledo, S., Kingscott-Edmunds, J., Bettridge, A., Waili, N.A. et al. (2017). Threesomes destabilise certain relationships: multispecies interactions between wood decay fungi in natural resources. FEMS Microbiol Ecol, 93.
Hiscox, J., Savoury, M., Vaughan, I.P., Müller, C.T. & Boddy, L. (2015). Antagonistic fungal interactions influence carbon dioxide evolution from decomposing wood.
Fungal Ecology, 14, 24-32.
Field, C.B., Barros, V.R., Mastrandrea, M.D., Mach, K.J., Abdrabo, M.-K., Adger, N. et al.
(2014). Summary for policymakers. In: Climate change 2014: impacts, adaptation, and vulnerability. Part A: global and sectoral aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change . Cambridge University Press, pp. 1-32.
Jonsson, B., Kruys, N. & Ranius, T. (2005). Ecology of species living on dead wood – lessons for dead wood management.
Karström, 1993 Indikatorarter som biologisk inventering metod-formulering av biologiska kriterier för urval av sökbiotoper. PP 19-98. In: GA. Olsson and M.
Granberg. Indikatorer för identifiering av naturskogar i Norrbotten.
Naturvårdsverket 4276, Solna.
Kauserud, H., Heegaard, E., Büntgen, U., Halvorsen, R., Egli, S., Senn-Irlet, B. et al.
(2012). Warming-induced shift in European mushroom fruiting phenology. 109, 14488-14493.
23
Lindner, D.L., Vasaitis, R., Kubartová, A., Allmér, J., Johannesson, H., Banik, M.T. et al.
(2011). Initial fungal colonizer affects mass loss and fungal community
development in Picea abies logs 6yr after inoculation. Fungal Ecology, 4, 449-460.
Matlack, G.R. (1993). Microenvironment variation within and among forest edge sites in the eastern United States. Biological Conservation, 66, 185-194.
Ottosson, E., Nordén, J., Dahlberg, A., Edman, M., Jönsson, M., Larsson, K.-H. et al.
(2014). Species associations during the succession of wood-inhabiting fungal communities. Fungal Ecology, 11, 17-28.
Parkinson, D., and Suzanne, V. & Whittaker, J.B. (1979). Effects of collembolan grazing on fungal colonization of leaf litter. Soil Biology and Biochemistry, 11, 529-535.
Penttilä, R., Lindgren, M., Miettinen, O., Rita, H. & Hanski, I. (2006). Consequences of forest fragmentation for polyporous fungi at two spatial scales. Oikos, 114, 225- 240.
Rinne-Garmston, K.T., Peltoniemi, K., Chen, J., Peltoniemi, M., Fritze, H. & Mäkipää, R.
(2019). Carbon flux from decomposing wood and its dependency on temperature, wood N2 fixation rate, moisture and fungal composition in a Norway spruce forest. Global Change Biology, 25, 1852-1867.
Renvall, P. (1995). Community structure and dynamics of wood-rotting Basidiomycetes on decomposing conifer trunks in northern Finland. Karstenia, 35, 1-51.
Rubenstein, M.A., Crowther, T.W., Maynard, D.S., Schilling, J.S. & Bradford, M.A.
(2017). Decoupling direct and indirect effects of temperature on decomposition.
Soil Biology and Biochemistry, 112, 110-116.
Sánchez, C. (2009). Lignocellulosic residues: Biodegradation and bioconversion by fungi. Biotechnology Advances, 27, 185-194.
Siitonen, J. (2001). Forest Management, Coarse Woody Debris and Saproxylic
Organisms: Fennoscandian Boreal Forests as an Example. Ecological Bulletins, 11- 41.
Siitonen, P., Lehtinen, A. & Siitonen, M. (2005). Effects of Forest Edges on the Distribution, Abundance, and Regional Persistence of Wood-Rotting Fungi.
Conservation Biology, 19, 250-260.
Soja, A.J., Tchebakova, N.M., French, N.H.F., Flannigan, M.D., Shugart, H.H., Stocks, B.J. et al. (2007). Climate-induced boreal forest change: Predictions versus current observations. Global and Planetary Change, 56, 274-296.
24
Thygesen, A., Bjerre, A., S. Schmidt, A., Jørgensen, H., Ahring, B. & Olsson, L. (2003).
Production of cellulose and hemicellulose-degrading enzymes by filamentous fungi cultivated on wet-oxidised wheat straw.
Toljander, Y.K., Lindahl, B.D., Holmer, L. & Högberg, N.O.S. (2006). Environmental fluctuations facilitate species co-existence and increase decomposition in communities of wood decay fungi. Oecologia, 148, 625-631.
van der Wal, A., Ottosson, E. & de Boer, W. (2015). Neglected role of fungal community composition in explaining variation in wood decay rates. Ecology, 96, 124-133.
Venugopal, P., Junninen, K., Linnakoski, R., Edman, M. & Kouki, J. (2016). Climate and wood quality have decayer-specific effects on fungal wood decomposition.
Forest Ecology and Management, 360, 341-351.
Venugopal, P., Junninen, K., Edman, M. & Kouki, J. (2017). Assemblage composition of fungal wood-decay species has a major influence on how climate and wood quality modify decomposition. FEMS Microbiology Ecology, 93, fix002-fix002.
Artfakta: SLU artdatabaken https://artfakta.se/artbestamning/taxon/phlebia-centrifuga- 1209
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Appendix 1a Example of Antrodia sinuosa forming mycelial cord-like structures
growing towards the agar plugs and eliminating the rest of the species when it was the initial species. The fungus seems to use the nutrients in the agar plugs of the other species before it starts to use more of the nutrients in the wood. photo taken at the end of the experiment.
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Appendix 1b. Example of Antrodia sinuosa replacing all other species at elevated temperature. It was also forming structures on the surface that looked like pores of a fruiting body. Photo taken at the end of the experiment.
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Appendix 1c. Example of P. centrifuga winning over A. xantha under normal temperature. Photo taken at the end of the experiment
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Appendix 2.
Photos of Phlebia centrifuga winning at both elevated (left) and normal (right) temperatures in all the replications when it was the prior species.25 PC 1 89 PC 1
26 PC 2 90 PC 2
29
27PC 3 91 PC 3
28 PC 4 92 PC 4
29 PC 5 93 PC 5
30
30 PC 6 94 PC 6
31 PC 3(2) 95PC 3(2)
32 PC 2(2)
96 PC 2(2)
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Appendix 3. Photos showing wood discs where Fomitopsis pinicola was initial species at elevated (left) and normal (right) temperature but was mostly dominated by Antrodia sinuosa. There were relatively more species left at the normal temperature.
33 FP 1 97 FP 1
34FP2 98 FP 2
32
5FP3 99 FP 3
36FP4 100 FP 4
37FP5 101 FP 5
33
38FP6 102 FP 6
39FP 7 103 FP 7
40 FP8 104 FP 8
