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Christian Science Monitor, August 13, 2015 Bloomfield, NM August, 2017
Soilmicrobial feedbacks to decomposition differences between native - - PowerPoint PPT Presentation
Soilmicrobial feedbacks to decomposition differences between native - - PowerPoint PPT Presentation
Soilmicrobial feedbacks to decomposition differences between native and invasive shrub species in an Animas River riparian zone Benjamin D. Duval NM Tech Duval Lab Co-authors Daniel Cadol (NMT-EES) Jamie Martin (Lab Manager) Bonnie Frey
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Leaf chemistry Soil Climate Microbial community
CO2
- rgN & P
Recalcitrant C forms
N2O
Energy for microbial biomass Mass loss Gas emissions Exo- enzymes Exo- enzymes
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Dissolved organic C
M+ M+
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Invasive species/N2 fixer High N litter
N2O emissions NO3
- leaching
Greater C-processing enzyme activity?
N loss?
= N limitation feedback that favors invasive “home field advantage”
Soil N
Elaeagnus
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Native species Modest N litter
N2O emissions NO3
- leaching
Greater N-processing enzyme activity?
N loss
= N mineralization feedback and “home field” advantage
Soil N
Populus
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Track sources of energy, C, N into aquatic food webs that feedback to metal cycling
Specific aim #1: learn something about different effects
- f native vs. invasive plants on key ecosystem process
Specific aim #2: Importance of litter chemistry vs. soil on gas flux and exo-enzyme activity
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Populus Salix Elaeagnus Tamarix
Soil Litter
Populus Populus Salix Elaeagnus Tamarix “Native” “Invasion”
3-month litter-soil incubations
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Soil Litter
Tamarix Populus Salix Elaeagnus Tamarix “Restore” “Invasive”
Populus Salix Elaeagnus Tamarix
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Mass Loss (final) Gas flux (weekly)
Mass pre vs. post %C = residual energy
13C = correlations with
microbial biomass CO2 = respiration/activity of heterotrophic bacteria, archaea & fungi N2O = N loss from (de)-nitrification
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cellulose chitin Microbial enzymes drive system-level C:N:P stoichiometry
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exo-enzyme Ecosystem function
1,4 β-glucosidase
Releases glucose from cellulose
1,4 N-acetyl glucosidase (NAG)
Breaks chitin and chitodextrins
Leucine amino peptidase (LAP)
Breaks peptide bonds, liberates N
Acid phosphatase
Mineralizes organic P into phosphate Microbial enzymes drive system-level C:N:P stoichiometry
Sinsabaugh et al. 2009 Nature
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Litter mass remaining after 90 days soil P S E T P
0.47 0.48 0.44 0.47
S
0.31 0.25 0.24 0.32
E
0.42 0.40 0.40 0.45
T
0.40 0.44 0.42 0.44
Populus Salix Elaeagnus Tamarix
16% 19% 18% 15% 4% 8% 5% 4%
range
range
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1) Most complete decomposition on Salix soil (Rs matches with mass loss) 2) Populus most evenly “active” soils over time
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4) Early peaks in Rs from Russian olive 3) No clear home field advantage by faster decomposition
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Soil type has greater control on C cycling than litter Mass loss explains both %C and 13C
litter soil
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Sustained N2O emissions from Russian olive Litter greater control
- n N-loss than soil
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Early in succession/decomposition/system development
- C limitation to enzyme production
- then > physiological need for N and P to
maintain cellular stoichiometry
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Aztec, New Mexico
Species matter (soil effects controlled by plants) Interactions/additive/counter-acting effects of litter community? Argues for inclusion of soil-microbial system information for making “restoration” policy
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Salix Tamarix Elaeagnus Populus