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Title: ATMOSPHERIC CO2 ENRICHMENT: IMPLICATIONS FOR ECOSYSTEM BIODIVERSITY

Author
item IDSO, KEITH - CTR...GLOBAL CHANGE TEMPE
item IDSO, SHERWOOD
item IDSO, CRAIG - CTR...GLOBAL CHANGE TEMPE

Submitted to: Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: As the number of people inhabiting the earth continues to grow, concern is rising about our impact on the rest of the biosphere. One of the major worries is that natural rates of species extinctions will be increased by various human activities that degrade the environment and that many ecosystems consequently will suffer irreparable reductions in biodiversity. This paper reviews the scientific literature to see what effects the ongoing rise in the air's carbon dioxide concentration may have on this problem. We find no evidence that atmospheric CO2 enrichment adversely affects genetic diversity within individual plant species nor that it negatively impacts the species richness of earth's ecosystems. Indeed, we find that more CO2 in the air should stimulate below-ground biological activity in ways that tend to increase ecosystem biodiversity. We also find that when atmospheric CO2 concentration and air temperature rise together, the natural ranges of plants, and the animals that feed upon them, expand and therefore overlap more, which also increases individual ecosystem species richness. In addition, the enhanced vegetative productivity that typically results from atmospheric CO2 enrichment tends to sustain greater herbivore and carnivore populations, which helps each such species maintain the critical biomass needed to maintain its individual genetic identity. We thus conclude that the ongoing rise in the air's CO2 content is a boom to the earth's many ecosystems, helping them to counter the negative environmental influences that tend to reduce their biodiversity.

Technical Abstract: Several experiments suggest that atmospheric CO2 enrichment will likely have no major impact on genotypic diversity within species, nor will it negatively impact the species richness of the vegetative components of the earth's ecosystems. A number of studies suggest that these consequences are determined by a suite of complex interactions that occur in the belowground environment, where plant roots intimately intermingle with various types of soil fungi in ways that sometimes actually tend to increase ecosystem biodiversity. Atmospheric CO2 enrichment also is effective in countering the biodiversity-degrading effects of global warming, as higher CO2 concentrations tend to ameliorate heat stress in plants and increase the temperatures at which plants function at their optimum. These phenomena enable plants to maintain the high-temperature boundaries of their ranges in the face of regional or global warming at the time that the warming allows them to push poleward at their low-temperature boundaries, thereby increasing their ranges. Herbivores that selectively feed on specific plants thus have the opportunity to do likewise, as do carnivores that feed on them; and with a greater overlapping of the ranges of both plants and animals, the biodiversities of nearly all of the earth's ecosystems tend to increase.