Climate change influence on decomposition and soil microbes

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Climate change influence on decomposition and
soil microbes

• Bob Edmonds

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Topics

• 1) Evidence for climate change in the Pacific
  Northwest
• 2) Influence of climate change on ecosystems
• 3) Effects of climate change on soil microbes and
  decomposition
• 4) Importance of lignicolous fungi
• 5) the diversity of fungi causing wood decay
• 6) brown versus white rot fungi
• 7) influence of global warming on wood decay
  fungi
• Temperature effects on fungi
• Influence on wood decay rates
• 8) Conclusions

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1. Evidence for climate change in the west

• Temperature and precipitation trends in WA, OR,
  CA, ID, MT and CO

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Temperature trends CA, OR
CA
OR
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Temperature trends WA, ID
WA
ID
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Temperature trends MT, CO
MT
CO
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Precipitation trends WA, ID
WA
ID
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Precipitation trends CA, OR
CA
OR
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Precipitation trends MT, CO
MT
CO

• CO

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2. Influence of climate change (CO2 and
temperature increase and changes in moisture) on
ecosystems

• Ecosystem responses to global warming will be
  complex and varied (Shaver et al. 2000)

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3) Effects of climate change on soil microbes and
decomposition
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• Global change will influence soil ecology
• Directly
• - Affecting the growth, survival and dispersal of
  soil
• organisms
• - Changing decomposition rates and C and N
  cycling
• Indirectly
• - Influencing plant productivity and litterfall
  rates and
• root turnover and soil organic matter
• Changing substrate chemistry
• Changing plant species composition
• Lots of feedback mechanisms

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Direct and indirect effects of climate change on
soil microbial communities and routes of feedback
to global warming through carbon dioxide
production. Direct effects include the influence
on soil microbes and greenhouse gas production of
temperature, changing precipitation and extreme
climatic events, whereas indirect effects result
from climate-driven changes in plant productivity
and vegetation structure which alter soil
physicochemical conditions, the supply of carbon
to soil and the structure and activity of
microbial communities involved in decomposition
processes and carbon release from soil Bardgett,
Richard D., Freeman, Chris, Ostle, Nicholas J.
2008. ISME JOURNAL   2  (8) 805-814 Microbial
contributions to climate change through carbon
cycle feedbacks     
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Elise Pendall, Lindsey Rustad, Josh Schimel.
2008. Towards a predictive understanding of
belowground process responses to climate change
have we moved any closer? Functional ecology
22(6) 937-940.

• Interacting effects of global change forcing
  factors on belowground processes act directly on
  plant communities to alter primary productivity,
  litter quantity and quality, and root production
  rates.
• Atmospheric CO2 concentrations have indirect
  effects on soil moisture, while temperature can
  alter N and moisture availability.
• The quantity and quality of soil organic matter
  and labile root exudates interact with microbial
  communities to alter rates of biogeochemical
  cycles.
• Microbial activity regulates belowground
  feedbacks to climate change by altering rates of
  decomposition and reactive N (e.g. N2O)
  production.

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• How do you study the effects of global warming?
• Soil heating cables or lamps
• Closed chambers CO2, temp, moisture
• Open (free air) chambers CO2
• Lab studies variable temp, moisture
• Mathematical simulation models

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Chen, H., Rygiewicz, P. T.Johnson, M. G.Harmon,
M. E.Tian, H., Tang, J. W. 2008. Chemistry and
long-term decomposition of roots of Douglas-fir
grown under elevated atmospheric carbon dioxide
and warming conditions JOURNAL OF ENVIRONMENTAL
QUALITY   37 (4)    1327-1336       Elevated
atmospheric CO2, concentrations and warming may
affect the quality of litters of form plants and
their subsequent decomposition in ecosystems,
thereby potentially affecting the global carbon
cycle. We used small diameter roots of
Douglas-fir seedlings that were grown for 4 yr
in a 2 x 2 factorial experiment ambient or
elevated ( 180 ppm) atmospheric CO2
concentrations, and ambient or elevated (3.8
degrees C) atmospheric temperature. Exposure to
elevated CO2 significantly increased
water-soluble extractives concentration, but
had little effect on the concentration of N,
cellulose, and lignin of roots. Elevated
temperature increased WSE and decreased the
lignin content of fine roots. This study
indicates that short-term decomposition (lt 9 mo)
and long-term responses are not similar. It also
suggests that increasing atmospheric CO2 had
little effect on the carbon storage of
Douglas-fir old-growth forests of the Pacific
Northwest.
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Richard T. Conant, J. Megan Steinweg, Michelle L.
Haddix, Eldor A. Paul, Alain F. Plante, Johan
Six. 2008. EXPERIMENTAL WARMING SHOWS THAT
DECOMPOSITION TEMPERATURE SENSITIVITY INCREASES
WITH SOIL ORGANIC MATTER RECALCITRANCE. Ecology
Vol. 89, No. 9, pp. 2384-2391. Soil C
decomposition is sensitive to changes in
temperature, and even small increases in
temperature may prompt large releases of C from
soils. Older, more-resistant C fractions may be
more temperature sensitive. We incubated soils at
constant temperature to deplete them of labile
soil OM and then successively assessed the CO2-C
efflux in response to warming. We found that the
decomposition response to experimental warming
early during soil incubation (when more labile C
remained) was less than that later when labile C
was depleted. These results suggest that the
temperature sensitivity of resistant soil OM
pools is greater than that for labile soil OM and
that global change-driven soil C losses may be
greater than previously estimated.
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Sokolov, Andrei P., Kicklighter, David W.,
Melillo, Jerry M., Felzer, Benjamin S.,
Schlosser, C. Adam, Cronin, Timothy W. 2008.
JOURNAL OF CLIMATE  21(15)3776-3796.   The
impact of carbon-nitrogen dynamics in terrestrial
ecosystems on the interaction between the carbon
cycle and climate was studied using an earth
system model of intermediate complexity, the MIT
Integrated Global Systems Model (IGSM).
Simulations show that consideration of
carbon-nitrogen interactions not only limits the
effect of CO2 fertilization but also changes the
sign of the feedback between the climate and
terrestrial carbon cycle. In the absence of
carbon-nitrogen interactions, surface warming
significantly reduces carbon sequestration in
both vegetation and soil by increasing
respiration and decomposition (a positive
feedback). If plant carbon uptake, however, is
assumed to be nitrogen limited, an increase in
decomposition leads to an increase in nitrogen
availability stimulating plant growth. The
resulting increase in carbon uptake by vegetation
exceeds carbon loss from the soil, leading to
enhanced carbon sequestration (a negative
feedback). Under very strong surface warming,
however, terrestrial ecosystems become a carbon
source whether or not carbon-nitrogen
interactions are considered. Models that ignore
terrestrial carbon-nitrogen dynamics will
underestimate reductions in carbon emissions
required to achieve atmospheric CO2 stabilization
at a given level.
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4. Importance of lignicolous fungi

• As a group, lignicolous fungi play a vital
  role in recycling the carbon and nutrients locked
  up in wood. Some species are capable of killing
  trees. They contribute CO2 to the atmosphere and
  organic matter to soil, and provide wildlife and
  plant habitat. They occur in all ecosystems with
  wood, including deserts
• Most are saprophytes on dead wood, but many
  invade living plant to decay heartwood.

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5. The diversity of fungi causing wood decay

• Each has its ecological niche

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Taxonomy and numbers of N. American wood-rotting
fungi(Gilbertson 1980)
Mostly basidiomycetes with a few ascomycetes
(Xylariaceae) may not be able to invade wood
without alteration by hyphomycetes, bacteria or
yeasts. Basidiomycete orders Tremellales 101
species Aphyllophorales 948 species Agaricales
620 species Total 1669 species
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Tremellales (jelly fungi)
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Aphyllophorales
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Agaricales
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Others
Birds nest
Puffball
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6. Brown versus white rot fungi

• There are fewer brown rot fungi (106 sp.) than
  white rot (1563 sp.) 6 of total
• They evolved from the white rot fungi.
• Majority of brown-rot fungi are in the
  Polyporaceae
• Most are associated with conifers
• Initially brown rot fungi cause greater weight
  loss in wood than white rot fungi.

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Brown rot versus white rotDoes it matter?Yes,
ecologically
http//ocid.nacse.org/classroom/fungi/bot461/
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The distribution of North American wood
rotting fungi is related to distribution of host
plants. However, species of wood decay fungi
are generally more widely dispersed than
species of higher plants (Gilbertson 1980).
But some like E. tinctorium only occur only
in the west even though suitable hosts (balsam
fir and Fraser fir occur in the east). So far
all species are endemic, as far as we know.
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7. Influence of global warming on fungi and wood
decay rates

• Effect of temperature on growth and wood decay
• Effect on fungal fruiting

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Temperature effects
On average optimum temperature for growth is
about 28 C as low as 20C and has high as 35 C
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Temperature accounts for 34 variation in CWD
decay rates
Mackensen et al. (2003)
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Rapid and recent changes in fungal fruiting
patterns in Britain

• Over 56 years 315 species, 1400 locations
• First fruiting date is now earlier and last
  fruiting
• date is later due to increases in later summer
• temperature and October rainfall. Many species
  now fruit in spring as well as fall.

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8. Conclusions

• We arent very good at understanding or
  predicting belowground process responses to
  climate change. What will happen to
• mycorrhizal fungi? Will their contribution
  as decomposers
• increase?
• 2. Global warming will increase decomposition
  and the decay
• rate of woody residues, but changing
  moisture will also play a role
• 3. Fungi will respond quickly to global
  warming
• 4. Fruiting patterns and spore production of
  wood rotting and other fungal species, including
  mycorrhizal fungi, will change
• 5. Woody residues will continue to decline with
  
• increase use of wood for timber, heating
  and biofuels
• 6. Some species of wood rotting fungi may go
  extinct, especially
• brown rot fungi