Measuring Photosynthesis in Grasslands

Grasslands cover 40% of the Earth's surface on 6 continents. They are a primary habitat for diverse organisms in each domain and are an important element in the carbon cycle. The plant communities are as diverse as the grasslands in which they are found, but some commonalities remain.

Perennial and annual monocot grasses have different phenology cycles, but both are highly dependent on water availability due to relatively shallow root structures and short lifecycles. This has influenced stomatal ratio and opening patterns as well as photosynthetic mechanisms. C4 photosynthesis separates photosynthetic carbon cycle components into different areas of the chloroplast, which allows a plant to begin active photosynthesis at lower CO2 and light levels. This in turn increases the efficiency of the transfer of carbon through biochemical cycles. With increased carbon fixation, the plant has the opportunity for more growth in a shorter period of time.

Trees, shrubs, and forbs are also commonly found in mixed grassland communities and their contribution to the carbon balance must be considered in any gas exchange measurement campaign. Trees typically have lower rates of net photosynthesis than other C3 plants, though there are some notable exceptions. Trees frequently are slower to respond to sudden biotic or abiotic changes.

LI-COR Photosynthesis Systems:

The LI-6400XT and LI-6800 Portable Photosynthesis Systems are compact, rugged, field portable instruments able to provide researchers with detailed information on plant responses such as CO2 assimilation rates, stomatal conductance, intercellular CO2 concentrations, carboxylation and light use efficiencies, and CO2 and light compensation points. The LI-6800 is our newest system, featuring a touch-screen interface and improvements in gas analyzer precision, better control over chamber conditions, and more.

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