How does rising atmospheric CO2 affect marine organisms?

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A Role for CO2 in Western Juniper Density and Cover Expansion?
Soule, P.T. and Knapp, P.A.  1999.  Western juniper expansion on adjacent disturbed and near-relict sites.  Journal of Range Management 52: 525-533.

What was done
The authors studied changes in the density and cover of western juniper (Juniperus occidentalis spp. occidentalis Hook.) on three sites of different land-use histories in central Oregon from 1951 to 1994.  They also evaluated a number of possible explanations for what they observed.

What was learned
The density of mature western juniper increased at all three sites over the entire period, as did the absolute cover at all three sites.  However, none of the mechanisms traditionally offered as explanations for the post-1800 expansion of western juniper (domestic grazing, altered fire regimes, favorable climatic conditions) was deemed adequate to explain the observations.

What it means
Compelled to consider the potential role of other influences, the authors speculated that the historical rise in the air's CO2 concentration, with its growth-enhancing and water use efficiency-increasing properties, may well have been a contributing factor to the western juniper cover and density increases.

Reviewed 1 January 2000