The contribution of trees and grasses to productivity of an Australian tropical savanna
Savanna ecosystems cover 20 % of the global land surface and account for 25 % of global terrestrial carbon uptake. They support one fifth of the world's human population and are one of the most important ecosystems on our planet. Savanna productivity is a product of the interplay between trees...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-04-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/13/2387/2016/bg-13-2387-2016.pdf |
| Summary: | Savanna ecosystems cover 20 % of the global land surface and account for
25 % of global terrestrial carbon uptake. They support one fifth of the
world's human population and are one of the most important ecosystems on our
planet. Savanna productivity is a product of the interplay between trees and
grass that co-dominate savanna landscapes and are maintained through
interactions with climate and disturbance (fire, land use change,
herbivory). In this study, we evaluate the temporally dynamic partitioning
of overstory and understory carbon dioxide fluxes in Australian tropical
savanna using overstory and understory eddy covariance measurements. Over a
2-year period (September 2012 to October 2014) the overall net ecosystem
productivity (NEP) of the savanna was 506.2 (±22 SE) g C m<sup>−2</sup> yr<sup>−1</sup>.
The total gross primary productivity (GPP) was 2267.1 (±80 SE)
g C m<sup>−2</sup> yr<sup>−1</sup>, of which the understory contributed 32 %. The
understory contribution was strongly seasonal, with most GPP occurring in
the wet season (40 % of total ecosystem in the wet season and 18 % in
the dry). This study is the first to elucidate the temporal dynamics of
savanna understory and overstory carbon flux components explicitly using
observational information. Understanding grass productivity is crucial for
evaluating fuel loads, as is tree productivity for quantifying the tree
carbon sink. This information will contribute to a significant refinement of
the representation of savannas in models, as well as improved understanding
of relative tree-grass productivity and competition for resources. |
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| ISSN: | 1726-4170 1726-4189 |