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CONTRASTING CLIMATIC

CONTROLS

ON THE ESTIMATED

PRODUCTIVITY

OF GLOBAL TERRESTRIAL

BIOMES

Galina Churkina and Steven W. Running

School of Forestry, University of Montona, Missoula, Montona 59812, USA

Reporters:

J.A.C. ManingasJ.M. del FIerro

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Definition of Terms

NPP-or net primary productivity represents the greatest annual

carbon flux from the atmosphere to the biosphere.

-causes fluctuation in atmospheric CO2 concentration.-it is the difference between the GPP and autotrophic

respiration

BIOME-BGC

-simulates global terrestrial NPP and assesses relativeimportance of climatic control (temperature, wateravailability and radiation) in limiting NPP in the arrayof climatic combinations found globally.

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Scope and Limitations

The study compares 7 different biomes.

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Deciduous Needle Leaf Forest

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Deciduous Broad Leaf Forest

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Evergreen Needle Leaf Forest

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Evergreen Broad leaf Forest

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Desert Shrubland

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C3 Grassland

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C4 Grassland

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Scope and Limitation Contd

The Study was conducted only in the

terrestrial biomes, no further

experimentation on the aquatic biomes were

mentioned on this study.

The study was conducted within a span of

one year, for the whole globe w/daily climate

based from CLIMATE

database

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Objectives

Determine areas of the globe whereclimactic control on NPP were importantand areas where nutrient availability/

biological constraints limited NPP morethan climate

Analyze relative contributions oftemperature and water availability to

potential vegetation productivity patternsaround the globe and to productivity ofdifferent biomes

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Methods

BIOME-BGC was used to estimate vegetationproductivity around the globe

NPP was calculated in terms of gas exchange @ 0.5x 0.5 spatial resolution

All computations were based on a 1 yr model runfor the whole globe w/daily climate based fromCLIMATE database.

7 biomes were considered in the model and wasclassified based on the following properties:

forest vs. grassesevergreen vs. decidious

broadleaf vs. needleleaf

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Methods

Factors that were studied as NPP-limiting

are temperature, water availability and

radiation

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Hypothesis

NPP or vegetation productivity is a result ofinteractions among several environmental

factors.

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Results

The productivity of most terrestrial

ecosystems was controlled by more than one

climactic factor, while NPP of some biomes

were not controlled by NPP at all.

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Results

In high latitudes(dark blue), temp.

appeared to be the

primary control on

NPP

In middle latitudes acombination of either

temperateure and

radiation (shades of

cyan) or temperature

and water availability(shades of magenta)

In lower latitudes,

water availability

(bright red) became

more dominant thanthe other 2 factors.

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Results

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Results

None of the climactic factors were limiting in

the tropical regions of South America, Africa

and South East Asia (dark grey to black on

the map)

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Conclusion

Productivity is controlled by more than oneenvironmental factor

Water availability and temperature affects NPP the

most, followed by radiation at 5% No climatic parameter appeared to limit vegetation

productivity in some areas of the globe particularly inthe tropical regions.

The map in the results can help determine what areas ofthe globe can be affected by environmental factors asidefrom climate.