How does rising atmospheric CO2 affect marine organisms?

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Effects of Plant Productivity on Herbivore Diversity
Reference
Siemann, E.  1998.  Experimental tests of effects of plant productivity and diversity on grassland arthropod diversity.  Ecology 79: 2057-2070.

What was done
The author studied the effects of short- and long-term nitrogen fertilization on plant productivity in upland grass field plots in Minnesota to determine the impacts of plant productivity on arthropod communities composed of herbivore, parasite, and predator species.

What was learned
Although long-term fertilization of nine years decreased plant diversity, it increased plant productivity; and this phenomenon caused an increase in arthropod species richness by significantly increasing the numbers of parasite and predator species.  Short-term fertilization also increased plant productivity, but without reducing plant diversity; and it too significantly increased arthropod diversity by increasing the species richness of herbivores, parasites, and predators.  These results demonstrate that increases in plant productivity lead to increases in the diversity of organisms higher up the food chain, such as herbivores, parasites and predators.

What it means
As the CO2 content of the air continues to rise, nearly all of earth's plants will produce more biomass.  The results of the present study suggest that these increases in plant productivity will lead to increases in arthropod diversity, including herbivores, parasites, and predators.  It is consequently conceivable that the rising CO2 content of the air will increase biodiversity in every corner of the globe where vegetation grows (and in some where it doesn't, as plants become more efficient in utilizing water and begin "to grow where no plant has grown before").


Reviewed 15 February 1999