Controls on aboveground net primary productivity & the - - PowerPoint PPT Presentation

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Controls on aboveground net primary productivity & the - - PowerPoint PPT Presentation

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Controls on aboveground net primary productivity & the partitioning of canopy and wood production in tropical rainforests Florian Hofhansl, & Wolfgang Wanek ATBC 2013 San Jos, Costa Rica Climatic Controls Introduction Global

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Controls on aboveground net primary productivity & the partitioning of canopy and wood production in tropical rainforests

Florian Hofhansl, & Wolfgang Wanek ATBC 2013 San José, Costa Rica

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Potential net primary production (NPP)

Introduction – Global carbon cycle Climatic Controls

Source: Schuur, E. Productivity and global climate revisited: The sensitivity of tropical forest growth to precipitation. Ecology, 84, 1165–1170.

Tropical Forests: 12%

  • f Earth's land surface

25%

  • f the world's biomass C

40%

  • f terrestrial NPP
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Temperature Precipitation

Introduction – Global carbon cycle Climatic Controls

Source: Schuur, E. Productivity and global climate revisited: The sensitivity of tropical forest growth to precipitation. Ecology, 84, 1165–1170.

Climatic drivers: Mean annual temperature (MAT) Mean annual precipitation (MAP)

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Introduction – Global carbon cycle

Source: IPCC - Climate Change 2007: Working Group I: The Physical Science Basis

Climate Projections

Expected changes: Drought frequency Precipitation intensity à à Temperature

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Net primary production (NPP): Aboveground NPP Belowground NPP Net primary production (NPP):

  • Canopy production (47%)
  • Wood production (53%)

Source: Malhi, Y..et al. (2011). The allocation of ecosystem net primary productivity in tropical forests. Philosophical Transactions of the Royal Society B: Biological Sciences, 366, 3225–3245.

Methodology

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Methodology

Net primary production (NPP): Aboveground NPP

  • Stem increment (ABI)
  • Litter fall (LF)

Relationship explained ABI ~ 60% LF ~ 40% à à about 50% undetermined

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Source: ISI webofknowledge.com

Methodology

< 1% measured both !!! Number of studies (ISI):

  • Net primary production
  • Stem increment
  • Litter fall
  • Stem increment &

Litter fall

23,116 8,474 6,833 30

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Local Study

Tropical Field Station La Gamba: (since 2005) Topographic positions:

  • Ridge
  • Slope
  • Ravine

Stem increment (DBH>10 cm) Litter fall (n=15 per site) www.univie.ac.at/bdef

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Introduction – Global carbon cycle Local Controls

Source: Hofhansl et al. (2013) Climatic controls on aboveground net primary productivity and the partitioning between canopy and wood production (in preparation).

Climatic controls: ANPP No sign. effect Stem increment (ABI) Precipitation Litter fall (LF) Drought and Temperature à à à à à à Different Controls ABI / LF

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Global Study

>100 sites, S-America (62), Asia (26), Hawaii (12), Africa (3), Australia (2) Parameters: MAT, MAP, DSL, CLD, Soil N:P, Litter N:P, Foliar N:P

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Introduction – Global carbon cycle Global Controls

Classification Tree (CART): MAT All forest sites (n=105) MAP Lowland Sites (>21.65°C) Soil N:P ratio Montane Sites (<21.65°C)

Source: Hofhansl et al. (2013) Climatic controls on aboveground net primary productivity and the partitioning between canopy and wood production (in preparation).

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Introduction – Global carbon cycle Global Controls

Structural equation model (SEM): Overall Model Lowland Model Montane Model

Source: Hofhansl et al. (2013) Climatic controls on aboveground net primary productivity and the partitioning between canopy and wood production (in preparation).

ABI ABI ABI LF LF LF

ANPP ANPP ANPP

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Introduction – Global carbon cycle Temperature

Effect Overall Lowland Montane ANPP

+ +

% WP

+

MAT

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Introduction – Global carbon cycle Precipitation

Effect Overall Lowland Montane ANPP

+

% WP

+ +

MAP

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Introduction – Global carbon cycle Soil N:P ratio

Effect Overall Lowland Montane ANPP

  • % WP
  • Soil N:P ratio
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Conclusion

  • Local Controls on ANPP differ for canopy & wood production
  • Global Controls on tropical ANPP:

MAT à (+) overall and montane ANPP, overall %WP MAP à (+) lowland ANPP, lowland & overall %WP Soil N:P à (−) overall and montane ANPP and %WP

  • Global change effects:

MAT à enhance productivity of montane forests MAP à alter C-sequestration potential of lowland forests Soil N:P à N-deposition might decrease tropical productivity

Conclusion

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Team of the Tropical Research Station La Gamba: Victor Cruz-Garcia, Luis Sanchez-Jimenez, Eduardo Arauz- Suarez Co-Workers: Sigrid Drage, Nina Hinko, Eva-Maria Pölz, Daniel Schaber Supervisors: Wolfgang Wanek, Andreas Richter, Roland Albert, Veronika Mayer, Anton Weissenhofer, Werner Huber Ministerio de Costa Rica: MINAE (Ministerio Nacional de Ambiente y Energia)

Acknowledgements

www.univie.ac.at/bdef