# Presentation: 523330

## a core project of the International Geosphere-Biosphere Programme

## Slide 2

## Objectives

- Ecosystem
- Physiology
- Salt Lake City, USA

- Agroecology and
- Production Systems
- Wallingford, UK

- Biodiversity and
- Community Structure
- Paris, France

- GCTE International Project Office Canberra, Australia
**http://gcte.org**

## Research Networks

- The Elevated CO2 Network
- Network of Ecosystem Warming Studies (NEWS)
**Biosphere-Atmosphere Stable Isotope Network (BASIN)**
- Crop Networks
-     wheat, rice, potato, cassava, tropical cereals, grain legumes, late blight
- Forest Networks
-     Environmental modifications, Age-related analyses
- Soil Networks
-     Soil Organic Matter NETwork (SOMNET), Soil Erosion Network (SEN)
- Network of Removal Experiments
*Proposed*:
- Exotic Invasions
- Fire Effects

## Biosphere-Atmosphere Stable Isotope Network (BASIN) Workshop

- Snowbird, UT, December 7-10, 1997

***The best long-term estimates of CO******2****** fluxes from soils and from terrestrial ecosystems will come from eddy flux measurement towers and from networks (AmeriFlux, EUROFLUX, LBA, MEDEFLU, etc.  Linking isotope studies to these CO******2****** flux sites allows for the critical long-term measurements of simultaneous ecosystem fluxes and isotope analyses.***

## At the global scale, the isotopic composition of CO2 may be used to partition oceanic and terrestrial sinks of carbon

At the ecosystem scale, stable isotopes may be used to partition the components of CO2 and water vapor fluxes

- At the global scale, the isotopic composition of CO2 may be used to partition oceanic and terrestrial sinks of carbon
- At the ecosystem scale, stable isotopes may be used to partition the components of CO2 and water vapor fluxes

## R

- Bowling et al. 1999
- GBC 13: 903-922

- Walker Branch, TN

- A

- A

- A

## = SFF + SDEF + Fao + Foa + Fap + Fba

- CA

- = SFF + SDEF + Fao + Foa + Fap + Fba

- = ( FF - A)SFF +  (DEF - A)SDEF + DoFao - ao(Fao + Foa)
- 	+ -Fap + (b - A )Fba

- anthropogenic CO2

- oceans

- biosphere

- photosynthesis

- respiration

- Fung et al. 1997 GBC 11: 507-533

## How sensitive are global carbon source/sink calculations to estimates

- of photosynthetic discrimination ()?

- Sensitivity analysis using SiB2-GCM:
- estimated	% of anthropogenic carbon
- Global  	absorbed by the biosphere
- 14.7 ‰ (all C4)		~100
- 20.0 ‰ (all C3)		~70

- leaf level  = a + (b - a) ci/ca
- 	    a = 4.4‰
- 	   b =27.5‰ (C3),  3-6‰ (C4)

## Slide 10

## Fessenden et al. unpublished

## Fessenden et al. unpublished

- (dry)

- (wet)

## NEECO2 = A + R

- isoflux = A (a - ) + R (r)

*isoflux, *a, r* are measured, and ** is modeled*

- NEEH2O = evaporation + transpiration
- soil CO2 flux = RA + RH

- Bowling et al. GCB *in press*

## Bowling et al. GCB in press

- Bowling et al. GCB *in press*

## Bowling et al. GCB in press

- Bowling et al. GCB *in press*

## NEECO2 = A + R

- isoflux = A (a - ) + R (r)

*isoflux, *a, r* are measured, and ** is modeled*

- NEEH2O = evaporation + transpiration
- soil CO2 flux = RA + RH

- Bowling et al. GCB *in press*

## BASIN North American sites

**BASIN North American sites**
- Florida slash pine
- Glacier Lake, Wyoming
- Harvard Forest
- Howland Forest
- Konza Prairie
- Lethbridge, Alberta
- Northern BOREAS spruce
- Northern Michigan
- Oregon Transect
- Park Falls, Wisconsin
- Wind River Canopy Crane

**http://gcte-focus1.org/basin.html**