controls on ecosystem responses to co 2
DESCRIPTION
- PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/1.jpg)
Soil-mediated effects of a CO2 gradient on grassland productivity: Interactions with resources and species
change.
Philip A. FayUSDA-ARS Grassland, Soil, and Water Lab
Temple, Texas U.S.A.
Collaborators: Wayne Polley (USDA-ARS)
Virginia Jin (USDA-ARS)Robert Jackson (Duke University)
Richard Gill (Brigham Young University)
Jack Morgan (USDA_ARS)Beth Newingham (University of Idaho)
![Page 2: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/2.jpg)
Controls on ecosystem responses to CO2
Species change
Ecosystem FunctionResources
CO2
![Page 3: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/3.jpg)
• Which resources (nutrients/water)?• Which species?• Where are each of these more/less important? • When do they become important ?• Sources of spatial variability:
Which? Where? When?
Species change
Ecosystem FunctionResources
CO2
Soils Climate
![Page 4: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/4.jpg)
Working model
CO2
Water
ANPPSpecies
Nutrients
Physiology
Mesic Xeric
Fine Coarse
AriditySoils
![Page 5: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/5.jpg)
Experiments
Mesic GrasslandMAP: 850 mm y-1
Semi-arid GrasslandMAP: 400 mm y-1
Mojave DesertMAP: 135 mm y-1
![Page 6: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/6.jpg)
• CO2 gradient since 2006 250 to 500 µL L-1
• Ambient temperature, average precipitation
• C4 vegetation• 3 soil types, 20 reps
Silty clay Sandy loam Clay
Mollisol Alfisol Vertisol
Mesic grassland
Fay et al. 2009 Ecosystems
![Page 7: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/7.jpg)
Mesic grassland
• Strongest CO2 effect on soils where:–High plant availability of soil moisture–Increased soil water content with CO2 (not shown)–A more productive grass became dominant.
Fay et al. 2012,Nature-Climate Change
Which resource? Water
![Page 8: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/8.jpg)
Mesic grassland
• Greater ANPP-CO2 response when direct + indirect effects present.• More CO2 effects present on coarser-textured soils.
Silty ClayCO2 Soil water
ANPPSpecies
Nitrogen
Physiology
Sandy LoamCO2 Soil water
ANPPSpecies
Nitrogen
Physiology
ClayCO2 Soil water
ANPPSpecies
Nitrogen
Physiology
Fine CoarseSoils
Fay et al. 2012,Nature-Climate Change
![Page 9: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/9.jpg)
Mesic grassland
• Which species?–Sorghastrum nutans
(Indiangrass)–Explains 45 – 65% of variation
in ANPP
Polley et al. 2012,Global Change Biol.
Silty Clay
Sandy Loam
Clay
![Page 10: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/10.jpg)
• Species
Mesic grassland
• When?
• Soil waterSilty Clay
Sandy Loam
Clay
Polley et al. 2012,Global Change Biol.
![Page 11: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/11.jpg)
Semi-arid grassland
• Mixed-grass prairie: 400 mm yr-1 MAP • C3 dominated, 600 ppm CO2 treatment
• CO2 enrichment: increased: photosynthesis, soil moisture and aboveground biomass.
• No change in plant N or community composition
CO2Soil Water
ANPPSpecies
Nitrogen
Physiology
Morgan et al. 2011, J. Morgan pers. Comm.
![Page 12: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/12.jpg)
More xeric systems• Mojave Desert: 135 mm yr-1 MAP• 550 ppm CO2 enrichment (FACE):
– Increased photosynthesis (wet years)– Increased LAI– No effect on soil moisture, total
aboveground biomass, or species biomass or cover.
Abov
egro
und
Bio
mas
s (g
/m2 )
0
50
100
150
200
250
Other All
Pleuraphis
rigidaLyc
ium
pallidu
mAmbrosia
dumosa Lar
rea
tridentataLyc
ium
andersonii
Non-Blower ControlAmbient CO2Elevated CO2
Treatment = 0.81Species < 0.0001
Treatment x Species = 0.84
Nowak et al. 2004Newingham et al. 2012.
CO2Soil Water
ANPPSpecies
Nitrogen
Physiology
![Page 13: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/13.jpg)
Summary
Mesic Xeric
Sandy LoamCO2
Soil water
ANPPSpecies
Nitrogen
Physiology
Soils • Interactions fewer with increasing aridity
Silty ClayCO2 Soil water
ANPPSpecies
Nitrogen
Physiology
MesicGrassland
CO2 Soil water
ANPPSpecies
Nitrogen
Physiology
ClayCO2 Soil water
ANPPSpecies
Nitrogen
Physiology
Fine CoarseSoils
Aridity/Precipitation
• Interactions more numerous on coarser soils
Semi-aridGrassland
CO2 Soil water
ANPPSpecies
Nitrogen
Physiology
Desert
CO2 Soil water
ANPPSpecies
Nitrogen
Physiology
![Page 14: Controls on ecosystem responses to CO 2](https://reader036.vdocuments.mx/reader036/viewer/2022062410/568163cc550346895dd50b00/html5/thumbnails/14.jpg)
Conclusion
Drier this way
More interactions that way
Local soils and regional climate are two important sources of spatial variability in the drivers of ecosystem responses to CO2 enrichment.